JPH11202193A - Focus detection device and camera with focus detection device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To perform focus detection at a position outside the center of the optical axis, reduce the influence of vignetting, and enable accurate focus detection. SOLUTION: At least three apertures which are arranged in an optical path between a photographing optical system 20 and a photoelectric conversion means 4 or in an optical path in the photographing optical system 20 and have different centers of gravity are provided. At least one from one opening
Selecting one opening as a first opening, selecting at least one opening having a center of gravity different from that of the first opening as a second opening, and setting the first and second openings to the light flux A pupil splitting means 3 which opens and closes in a time-division manner, and a focus detecting means (operation control means) for detecting a focus state of the photographing optical system 20 based on an image signal of the subject image formed on the photoelectric conversion means 4 5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detection device of a pupil time-division type image shift detection system for detecting an image shift by alternately switching an opening provided near an exit pupil position of an optical system, and a focus detection device. It is about cameras.

[0002]

2. Description of the Related Art As a conventional focus detecting device, a pupil time-division type image shift detecting type focus detecting system which detects an image shift by alternately using a pair of apertures provided near an exit pupil position of an optical system. Detection devices are known. This focus detection device has the following configuration. That is, a pair of apertures set in the vicinity of the exit pupil of the photographing optical system are alternately used, and a subject image (hereinafter, referred to as a pair of subject images) is formed alternately on the imaging plane of the photographing optical system. The pair of subject images are alternately photoelectrically converted by an image sensor arranged on an imaging surface of the photographing optical system in synchronization with the switching of the aperture. Therefore, the image sensor outputs a pair of image data corresponding to the pair of subject images. The focus state of the photographing optical system is obtained by detecting a shift between the pair of image data.

The following is known as means for alternately opening and closing the pair of openings. For example, a mask plate having an aperture off the center of the optical axis on the stop surface of the photographing optical system is rotated about the optical axis by a motor or the like. Then, in synchronism with the rotation of the mask plate, the charge is accumulated by a CCD image sensor provided on the imaging surface of the photographing optical system.

[0004]

The conventional focus detection apparatus based on the pupil time-division type image shift detection method has the following problems. In other words, since the position of the pair of apertures when photoelectric conversion is performed by the image sensor is predetermined, focus detection is performed at a position outside the optical axis of the object scene (for example, a position around the screen). The light flux passing through the pair of apertures is unbalanced in light quantity due to vignetting by the exit pupil.
Therefore, a phenomenon occurs in which the identity of a pair of formed images is lost, and the focus detection accuracy is deteriorated or the focus cannot be detected.

An object of the present invention is to provide a pupil time-sharing method capable of accurately detecting a focus by reducing the influence of vignetting even when the focus is detected at a position outside the optical axis of the object field. A focus detection device. Another object of the present invention is to reduce the influence of vignetting even when performing focus detection at a position outside the optical axis of the field of view, and to achieve a pupil time division method capable of accurately performing focus detection. It is to provide a camera with a focus detection device.

[0006]

According to a first aspect of the present invention, there is provided a photoelectric conversion means disposed on an image forming plane of a photographing optical system for forming an image of a light beam from a subject and converting the image of the subject into an image signal. And at least three apertures that are arranged in an optical path between the imaging optical system and the photoelectric conversion unit or in an optical path in the imaging optical system and have different centers of gravity from each other. At least one opening is selected as a first opening, and at least one opening having a different center of gravity from the first opening is selected as a second opening, and the first and second openings are selected. Pupil division means for opening and closing the light beam in a time-division manner, and focus detection for detecting a focus state of the photographing optical system based on an image signal of the subject image formed on the photoelectric conversion means by the pupil division means hand Characterized by comprising and.

According to the first aspect of the present invention, the first opening and the second opening are respectively formed by selecting at least one opening from three openings having different centers of gravity. Therefore, when focus detection is performed at a position off the optical axis (for example, at a position around the screen), the first opening and the second opening are appropriately selected from at least three openings, so that the first opening is formed. It is possible to prevent a phenomenon in which a light beam passing therethrough and a light beam passing through the second opening are unbalanced in light amount due to vignetting. Therefore, when focus detection is performed at a position off the optical axis, it is possible to provide a focus detection device capable of accurately detecting a focus state.

According to a second aspect of the present invention, there is provided a photographing optical system for forming an image of a light beam from a subject, and photoelectric conversion means for receiving an image of the subject formed by the photographing optical system and converting the image into an image signal. And at least three apertures that are arranged in an optical path between the imaging optical system and the photoelectric conversion unit or in an optical path in the imaging optical system and have different centers of gravity from each other. At least one
Selecting one opening as a first opening, selecting at least one opening having a center of gravity different from that of the first opening as a second opening, and setting the first and second openings to the light flux A pupil division unit that opens and closes in a time-division manner, and a focus detection unit that detects a focus state of the imaging optical system based on an image signal of an image of the subject formed on the photoelectric conversion unit by the pupil division unit. It is characterized by having.

According to the second aspect of the present invention, the first opening and the second opening are respectively formed by selecting at least one opening from three openings having different centers of gravity. Therefore, when focus detection is performed at a position off the optical axis (for example, at a position around the screen), the first opening and the second opening are appropriately selected from at least three openings, so that the first opening is formed. It is possible to prevent a phenomenon in which a light beam passing therethrough and a light beam passing through the second opening are unbalanced in light amount due to vignetting. Therefore, when focus detection is performed at a position outside the optical axis, it is possible to provide a camera including a focus detection device capable of accurately detecting a focus state.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. (Explanation of Principle of Focus Detection) First, the principle of focus detection will be described with reference to the drawings. 1 to 4 are schematic diagrams for explaining the principle of focus detection by the pupil time division type image shift detection method.

FIG. 1 shows two apertures 202 and 203 provided at an exit pupil position 201 of an imaging optical system and a photoelectric conversion means 2.
It is explanatory drawing which shows 04. As shown in the figure, a pair of apertures 202 and 2 are located at an exit pupil position 201 with an optical axis 205 interposed therebetween.
03 is provided. Here, each opening 202, 203
Are located at different positions from each other, and the openings 202,
203 is not provided at the same position. Also,
The photoelectric conversion unit 204 is arranged on a predetermined imaging plane of the imaging optical system.

FIGS. 2 to 4 are cross-sectional explanatory views of the imaging optical system shown in FIG. 1 as viewed from above. In the following description, the subject is described as a point light source (not shown) on the optical axis 205 of the imaging optical system. (A), (b) of FIG.
FIG. 3 is a diagram showing a state where the imaging optical system is in focus. As shown in the figure, each light beam from a point light source passing through the aperture 202 and the aperture 203 forms an image at the same position A on the photoelectric conversion means 204.

FIGS. 3A and 3B are diagrams showing a front focus state in which the focal position of the imaging optical system is located before the in-focus position. As shown in FIG.
2 from a point light source passes through a photoelectric conversion unit 204.
An image is formed at the upper position B. On the other hand, as shown in FIG. 3B, a light beam from a point light source passing through the opening 203 forms an image at a position C on the photoelectric conversion means 204.

FIGS. 4A and 4B are diagrams showing a back focus state in which the focal position of the imaging optical system is located after the in-focus position. As shown in FIG.
The light flux from the point light source passing through 2 forms an image at a position D on the photoelectric conversion means 204. On the other hand, as shown in FIG. 4B, the light flux from the point light source passing through the aperture 203 forms an image at a position E on the photoelectric conversion means 204.

As described above, the image position on the photoelectric conversion means 204 changes according to the focus state of the imaging optical system. Therefore, the aperture 202 and the aperture 202 are located on the exit pupil position 201 of the imaging optical system.
203, the aperture 2 provided at the exit pupil position 201
02 and 203 are shielded from light,
203 is opened and closed alternately over time, and the positional relationship between the image signal captured by the photoelectric conversion unit 204 when the opening 202 is opened and the image signal captured by the photoelectric conversion unit 204 when the opening 203 is opened (image By detecting the shift direction and the shift amount, the focus state and the focus shift amount (hereinafter, referred to as a defocus amount) of the imaging optical system can be detected.

(Embodiment) <Structure of Embodiment> FIG. 5 is an explanatory diagram showing a schematic structure of an embodiment when a focus detection device of the present invention is applied to a single-lens reflex camera. As shown in FIG. 5, the single-lens reflex camera includes a camera body 1 and an interchangeable lens structure 2.

As shown in the figure, the interchangeable lens structure 2 includes a photographing optical system 20, pupil dividing means 3 arranged near the exit pupil position of the photographing optical system 20, and information on the photographing optical system 20 and the pupil dividing means 3. And information means 21 for outputting the information to the outside. In the embodiment shown in FIG. 5, the pupil dividing means 3 is arranged in the optical path of the photographing optical system 20. As shown in the figure, the camera body 1 includes a pentaprism 10, a shutter 11, a film 12, and a light beam from the photographing optical system 20.
A sub-mirror 14 for further deflecting the light beam passing through the main mirror 13 to the bottom of the camera body 1, a photoelectric conversion means 4 including a CCD sensor or the like for receiving the light beam deflected by the sub-mirror 14. , Controls the operations of the pupil dividing means 3 and the photoelectric conversion means 4, receives a signal from the photoelectric conversion means 4, calculates an image shift amount based on the signal, and calculates the image shift amount and the information means 21. And an arithmetic control unit 5 for detecting the amount of defocus (amount of defocus) of the photographing optical system 20 based on the above information.

In the above arrangement, the pupil dividing means 3 alternately blocks a pair of apertures arranged in the optical path near the exit pupil of the photographing optical system 20 in a time-sharing manner under the control of the arithmetic control means 5. Having. Further, the photoelectric conversion unit 4 is disposed near a surface optically conjugate with the surface on which the film 12 is disposed. Observation of a subject image is possible with a light beam passing through the pentaprism 10. The camera body 1 and the interchangeable lens structure 2 can be mounted / removed.

When the camera body 1 and the interchangeable lens structure 2 are mounted, the pupil dividing means 3 and the information means 21 communicate with the arithmetic and control means 5 via a mounting part (mount part).
The information unit 21 generates the following information on the photographing optical system 20. Focal length Aberration information (information on spherical aberration, curvature of field, etc.) Information on vignetting of imaging light flux (information on outer shape and position of each lens, outer shape and position of aperture and hood, etc.) Generates the following information: Opening shape, position in optical axis direction, position in exit pupil plane Opening / closing state of opening

<Operation of the Embodiment> The pupil dividing means 3 is fully open before being activated by an operation member (main switch of the camera or the like) not shown. Therefore, the photographer can observe the subject through the pentaprism 10.

Next, when the operation control means 5 is started by an operation member (not shown), the operation control means 5
, And a pair of openings are alternately opened and closed in a time sharing manner. The photoelectric conversion unit 4 outputs an image signal when one opening is open and an image signal when the other opening is open, in synchronization with opening and closing the pair of openings alternately in a time-division manner. .

The arithmetic control means 5 performs an image shift detection operation on the two image signals by a well-known correlation operation.
An image shift amount, which is a relative displacement between two image signals, is calculated. Further, the arithmetic and control unit 5 converts the image shift amount into a defocus amount in the optical axis direction according to information on the shape of the opening, the optical axis direction, and the position in the exit pupil plane from the information unit 21. . Further, the arithmetic and control unit 5 responds to the information on the aberration of the photographing optical system from the information unit 21,
The defocus amount is corrected, and a final defocus amount is calculated.

That is, the arithmetic and control means 5 comprises:
2 has the role of the focus detection means. In accordance with the defocus amount finally calculated by the arithmetic and control unit 5, the photographing optical system 20 is driven in the optical axis direction by an actuator (not shown) (built in the camera body 1 or the interchangeable lens structure 2) to automatically focus. May be performed, or the defocus state may be displayed by a display unit (not shown). In the above-described embodiment, the arithmetic control unit 5 may be configured to be built in the interchangeable lens structure 2.

<Structure of Pupil Dividing Means 3> FIG. 6 is a diagram showing a specific example in which the pupil dividing means 3 is constructed using a liquid crystal shutter. FIG. 6 is a view of the pupil dividing means 3 viewed from the optical axis direction. As shown, a concentric region 4 around the optical axis
1, 42, 43 and a pair of openings 44, 45 are constituted by liquid crystal shutters. Each area 41, 42, 43 and opening 4
4, 45 are configured to be capable of independently applying a voltage.

The concentric regions 41, 42 and 43 are configured such that the photographing aperture is constituted by a liquid crystal shutter. Therefore, in this example, the pupil dividing means 3 and the photographing aperture are also used. According to this configuration, the number of components can be reduced.

<Operation of Pupil Dividing Means 3>
(B) is a figure which shows operation | movement of the pupil division means 3. As shown in the drawing, by applying a voltage to a region other than the opening 44 or the opening 45, as shown in FIGS.
A region other than the opening 44 or the opening 45 can be in a light blocking state, and only the opening 44 or the opening 45 can be in a light transmitting state.
When functioning as a photographing aperture, a voltage may be applied to a region outside a desired aperture outer diameter. In the above configuration,
When no power is supplied, the pupil dividing means 3 is in a transparent state, so that it is possible to observe through the finder even when the power is off, which is advantageous when used as a single-lens reflex camera.

<Structure of Liquid Crystal Shutter> FIGS.
FIG. 2B is a diagram showing a liquid crystal shutter constituting the pupil dividing means 3. FIGS. 8A and 8B show TN as a liquid crystal.
(TWISTED NEMATIC) A liquid crystal shutter using a liquid crystal. As shown, the TN liquid crystal has the following configuration. That is, the substrate on which the liquid crystal molecules 30 are sandwiched includes a glass substrate 31, a polarizing plate 33 or 34 provided on the outer surface of the glass substrate 31, and a transparent electrode 32 provided on the inner surface of the glass substrate 31. Here, the polarizing plates 33 and 34 are provided in an arrangement in which the polarization directions are orthogonal to each other. The liquid crystal shutter has a power supply 3
5 and a switch 36 are provided. The power supply 35 applies a voltage between the transparent electrodes 32.

<Operation of Liquid Crystal Shutter> As shown in FIG. 8A, when the switch 36 is turned off and no voltage is applied between the transparent electrodes 32, the following operation is performed. That is, the liquid crystal molecules 30 are aligned in a direction parallel to the transparent electrode 32, and the incident light is polarized by the layer of the liquid crystal molecules 30 in the direction of 90 degrees.
Rotate degrees. Therefore, the incident light is transmitted through the polarizing plate 3 on the output side.
Go through 4 as it is.

As shown in FIG. 8B, the switch 36
Is turned on, and a voltage is applied between the transparent electrodes 32, the following operation is performed. That is, the liquid crystal molecules 30 are oriented in a direction perpendicular to the transparent electrode 32, and the polarization direction of the incident light is not rotated in the layer of the liquid crystal molecules 30. Therefore, the incident light beam cannot pass through because it is blocked by the polarizing plate 34 on the emission side.

In the case of a TN liquid crystal, the polarizing plate 33,
According to the characteristic of 34, it is possible to configure so that the incident light is transmitted when the switch 36 is turned off, and the incident light is blocked when the switch 36 is turned on.

<Structure of Photoelectric Conversion Means 4> FIG. 9 is an explanatory diagram showing an example in which the photoelectric conversion means 4 is constituted by a two-dimensional CCD sensor. As illustrated, the photoelectric conversion unit 4 has a configuration in which the photoelectric conversion pixels 51 are two-dimensionally arranged. By disposing a two-dimensional CCD sensor as the photoelectric conversion means 4, it is possible to two-dimensionally detect the focus state of the imaging optical system 20.

As shown in FIG. 9, the photoelectric conversion pixels 51 used for the focus detection calculation to be described later are divided into the areas 46, 47 and 4.
By arbitrarily selecting as in 8, it becomes possible to detect the focus state at the position corresponding to each of the regions 46, 47 and 48 on the photographing screen. FIG. 10 is a partially enlarged view of the two-dimensional CCD sensor shown in FIG. As shown, the CCD sensor includes a photoelectric conversion pixel 51, a pair of gates 52 and 53, a pair of charge storage units 54 and 55, a gate 56, and a CCD charge transfer unit 57.

Since the conventional CCD sensor has only one charge accumulating section for one photoelectric conversion pixel, when the aperture of the pupil dividing means 3 is switched, the image is previously accumulated each time to take in the next image. It is necessary to output the electric charge as an electric signal to the outside. According to the CCD sensor shown in FIG. 10, one photoelectric conversion pixel 51 is provided with a pair of gates 52 and 53 and a pair of charge storage units 54 and 55. Therefore, when the opening is switched, the gate 5
2 and 53, the charges corresponding to the image of the subject formed by the different apertures are stored in different charge accumulating units 5.
4,55.

Since it is sufficient to transfer the electric charge after the completion of the accumulation and output the electric charge to the outside, it is possible to cope with the case where the aperture is switched at a high speed. Further, by using a two-dimensional CCD sensor, it is possible to detect a focus at an arbitrary position in a shooting screen.

<Operation of Photoelectric Conversion Means 4> In FIG. 10, the photoelectric conversion pixel 51 generates a charge corresponding to the amount of incident light. The gates 52 and 53 are closed before charge accumulation, and the generated charge is discarded to a drain (not shown). Gates 52 and 53 alternately open and close during charge accumulation. Therefore, the charge generated in the photoelectric conversion pixel 51 while the gate 52 is open is stored in the charge storage unit 54, and the charge generated in the photoelectric conversion pixel 51 while the gate 53 is open is stored in the charge storage unit 55. Is done. During this time,
Gate 56 is closed.

When the charge accumulation is completed, the gates 52 and 53 are closed, and then the gate 56 is opened.
Move to the charge transfer section 57. Thereafter, the electric charge transferred to the CCD electric charge transfer section 57 is transferred according to the operation clock of the CCD, and is output to the outside as an electric signal.

<Synchronous operation of aperture switching and charge accumulation> FIG.
FIG. 1 is a diagram showing operation timings of opening switching and charge storage. FIG. 11C shows a period during which the opening 44 shown in FIG. 6 performs the opening and closing operation. Therefore, charges are stored in the charge storage unit 54 shown in FIG. 10 over this period. FIG. 11D illustrates a period during which the opening 45 illustrated in FIG. 6 performs the opening and closing operation. Therefore, charges are stored in the charge storage unit 55 shown in FIG. 10 over this period.
FIG. 11A is a diagram showing details of FIG. 11C. As shown in FIG. 11A, the opening 44 shown in FIG.
Are repeatedly opened and closed during the ON period and closed during the OFF period. This signal is applied to gate 52.

FIG. 11B is a diagram showing details of FIG. 11D. As shown in FIG. 11B, the opening 45 shown in FIG. 6 is repeatedly opened and closed in the ON period and closed in the OFF period. This signal is applied to the gate 53.

FIG. 11E shows the charge storage units 54 and 55
FIG. 4 is a diagram showing a charge transfer period after the end of charge accumulation. FIG.
The signal waveform shown in FIG. 1A and the signal waveform shown in FIG. 11B have an opposite phase relationship, and are repeatedly turned on / off.
That is, the signal waveform shown in FIG. 11A is applied from the arithmetic and control unit 5 to the opening 44 shown in FIG.
This is applied to the gate 52 shown in FIG.

The signal waveform shown in FIG. 11B is applied from the arithmetic and control unit 5 to the opening 45 shown in FIG. 6 and also to the gate 53 shown in FIG. Therefore, the opening 44 and the opening 45 are alternately opened and closed alternately, and the charge photoelectrically converted during the opening of the opening 44 is accumulated in the charge storage unit 54, and the charge is photoelectrically converted during the period of the opening 45. The charge is stored in the charge storage unit 55.

In FIG. 6, an ON signal is applied to the regions 41, 42, 43 other than the openings 44, 45 during the operation period of the openings 44, 45, and an OFF signal is applied during the other periods. In this way, the pupil dividing means 3 is in the fully open state except during the operation of the openings 44 and 45. Therefore, the image of the subject can be observed with the viewfinder, which is advantageous when used as a single-lens reflex camera.

It is also conceivable that the openings 44 and 45 are switched only once to store charges. However, in this case, there is a possibility that the difference between the charge accumulation amounts due to the two openings becomes large. That is, due to the movement of the subject in the optical axis direction or the direction perpendicular to the optical axis direction generated between the charge accumulation by the two apertures, or the movement of the subject image on the image plane due to camera shake, The error may be a non-negligible amount. As in the embodiment of the present invention, by alternately repeating the switching of the openings and the charge accumulation, there is an advantage that the deviation of the charge accumulation amount can be reduced.

Calculation processing of calculation control means 5> The electric signal output from the photoelectric conversion means 4 is A / D converted into digital data by the calculation control means 5, and the image shift amount is calculated based on the obtained digital data. Is done. Basically, data A corresponding to the subject image formed by the aperture 44
Correlation calculation is performed while relatively shifting data Bi (i = 1 to n) corresponding to the subject image formed by i (i = 1 to n) and the opening 45, and the relative shift amount having a high degree of correlation is calculated. An image shift amount between the two images is calculated.

Since the relative shift amount can actually take only an integer value, a value equal to or less than the integer value of the image shift amount is obtained by interpolation. As a method of the correlation calculation, there are a first method of calculating a sum of absolute values of differences between data and a second method of calculating a sum of multiplications between data. The first method has a merit that the smaller the total amount is, the higher the correlation degree is, that the calculation time can be shortened, and that there is a disadvantage that an error is large when there is a crosstalk or offset between data.

The above-mentioned second method has a demerit that the larger the total amount is, the higher the correlation degree is, and it takes a long calculation time, but has a merit that an error is small even when there is an offset between data. . Switching the aperture actually requires a transition time. Therefore, the obtained data often has crosstalk components mutually. The ratio of the crosstalk component of the data is determined in advance by experiments,
By individually measuring during assembly, it is possible to correct it by arithmetic processing. Next, a correction method will be described.

Data Ai = αi + bi (1) Data Bi = βi + ai (2) where αi is an effective component included in data Ai bi is a crosstalk component included in data Ai βi is an effective component included in data Bi The component ai is a crosstalk component included in the data Bi.

The crosstalk ratio K = (ai for αi
Assuming that (ratio of bi) to (ratio of bi with respect to βi), by correcting the data based on the following equation, it is possible to obtain data of only an effective component that does not include a crosstalk component. Data A′i = Ai−K × Bi = αi−K × ai (3) Data B′i = Bi−K × Ai = βi−K × bi (4) The corrected data A′i If the correlation operation is performed while relatively shifting B′i, the influence of crosstalk is eliminated.
The image shift amount L between the images can be calculated.

The pupil dividing means 3
(Frequency characteristics of opening switching, temperature characteristics) and characteristics (frequency characteristics, temperature characteristics, etc.) of the photoelectric conversion means 4 and the focus detection position, so that the arithmetic control means 5 is obtained from the information means 21. Based on the characteristic information of the pupil dividing means 3, the characteristics of the photoelectric conversion means 4 and the operating environment parameters (temperature, drive frequency, accumulation time, etc.) and focus detection conditions (focus detection position, etc.) stored in advance by the arithmetic control means 5. The crosstalk ratio K is calculated.

When the focus detection position is not on the optical axis, the luminous flux reaching the focus detection position is asymmetric, so that the crosstalk ratio K is also different from the data A'i and B'i. The talk ratios K1 and K2 are set. Data A′i = Ai−K1 × Bi = αi−K1 × ai (5) Data B′i = Bi−K2 × Ai = βi−K2 × bi (6) When a dimensional CCD sensor is used, the data used for the above calculation is, for example, data in the areas 46, 47, and 48 in FIG.

Next, the image shift amount L (x, y) is converted into a focus shift amount in the optical axis direction = a defocus amount D (x, y). Here, x and y are parameters for specifying the focus detection position in two dimensions. Here, the conversion coefficient is assumed to be S (x, y).

D (x, y) = S (x, y) × L (x, y) (7) The conversion coefficient S (x, y) is a characteristic of the pupil division means 3 (aperture shape, pupil plane In the optical axis direction), the characteristics of the imaging optical system 20 (the outer shape and position of each lens, the outer shape and position of the aperture and hood, etc.), and the focus detection position. Therefore, the conversion coefficient S (x, y) is determined by the information means 2
1 and the characteristic information of the pupil dividing means 3 and the photographing optical system 2
The calculation is performed by the calculation control means 5 based on the characteristic information of 0 and the focus detection position information set by the calculation control means 5 or the photographer.

The correction amount C (x, y) is added to the defocus amount D (x, y) calculated by the equation (7), and the correction defocus amount D '(x, y) is calculated. D ′ (x, y) = D (x, y) + C (x, y) (8) The correction amount C (x, y) is determined by the characteristics of the pupil division means 3 (the aperture shape, the pupil plane It changes in relation to the aperture position, the position in the optical axis direction), the characteristics of the photographing optical system 20 (the outer shape and position of each lens, the outer shape and position of an aperture and a hood, aberrations, etc.) and the focus detection position. Therefore, the correction amount C (x, y) is obtained by the characteristic information of the pupil dividing unit 3 and the characteristic information of the photographing optical system 20 obtained from the information unit 21 and the focus detection position information set by the arithmetic control unit 5 or the photographer. Is calculated by the calculation control means 5 based on

When the focus detection is performed at one designated position, the corrected defocus amount D 'calculated by the equation (8) is used.
Based on (x, y), the focus adjustment drive of the imaging optical system 20 is performed, and the focus adjustment state is displayed. When the focus detection is performed at a plurality of positions, based on the plurality of corrected defocus amounts D '(x, y) corresponding to the plurality of positions, a correction defocus amount indicating the closest distance is selected from among them.
The final defocus amount is calculated by calculating the average defocus amount of the plurality of defocus amounts. Then, based on the final defocus amount, the focus adjustment drive of the imaging optical system 20 is performed, and the focus adjustment state is displayed.

(Variation of Embodiment) FIG.
FIG. 6 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. 5 (an embodiment in which the focus detection device according to the present invention is applied to a single-lens reflex camera). The difference between the embodiment shown in FIG. 5 and the embodiment shown in FIG. 12 is that the pupil dividing means 3 is not built in the interchangeable lens structure 2 but is built in the camera body 1. . The pupil dividing means 3 includes a photographing optical system 20 and a main mirror 13
In the light path between the two.

An advantage of the embodiment shown in FIG. 12 is that the position of the pupil dividing means 3 is constant without depending on the type of the interchangeable lens structure 2, so that the focus detection accuracy is stabilized. Further, since the pupil dividing means 3 is not built in the interchangeable lens structure 2, the cost of the interchangeable lens can be reduced. Further, since the pupil dividing means 3 is not built in the interchangeable lens structure 2, focus detection can be performed even with a conventional interchangeable lens.

Since the pupil dividing means 3 and the arithmetic control means 5 are incorporated in the camera body 1, the pupil dividing means 3 and the arithmetic control means 5 are fixed.
As compared with the case where the pupil dividing means 3 is incorporated in the camera, the complexity of the control operation can be reduced, and the operation of the pupil dividing means 3 can be optimized. Specifically, when the pupil division means 3 is provided in the interchangeable lens structure 2, it is difficult to match a large number of pupil division means 3 having different characteristics with the arithmetic control means 5. However, by providing the pupil division means 3 in the camera body 1, only the matching between one pupil division means and the arithmetic control means 5 needs to be considered, so that there is an advantage that adjustment at the time of assembling becomes easy. When the pupil dividing means 3 is provided in the interchangeable lens structure 2, it is necessary to store information on the pupil dividing means 3 in the information means 21. However, providing the pupil division means 3 in the camera body 1 eliminates the need for the information means 21 to store information about the pupil division means 3.

In the embodiment shown in FIG. 12, the photometric means 27 is located near the eyepiece surface of the pentaprism 10.
Are arranged, and the luminance of the subject is measured through the photographing optical system 20. However, the photometric means 27 is the pupil dividing means 3
Even if the photometry is performed during the operation (during the ON periods shown in (c) and (d) of FIG. 11), accurate photometry cannot be performed because the luminous flux is restricted by the pupil division means 3. Therefore, when the pupil dividing unit 3 is operating, the arithmetic control unit 5 prohibits the photometric operation by the photometric unit 27.

During the operation of the pupil dividing means 3 (FIG. 11 (c),
In the case where the photometry means 27 is inevitably to perform photometry during the (d) ON period, the measured luminance is corrected by the amount of light limited by the pupil division means 3. The photometric unit 27 corrects based on, for example, the area ratio when the opening 44 or 45 shown in FIG. 6 is in the transmitting state and when all the regions 41 to 45 are in the transmitting state.

The amount of photometric correction is determined by the characteristics of the pupil dividing means 3 (opening shape, opening position in the pupil plane, position in the optical axis direction) and the characteristics of the photographing optical system 20 (outer shape and position of each lens, aperture and hood). Of the photometric unit 27 and the configuration of the finder optical system.
Therefore, the photometric unit 27 calculates based on the characteristic information of the pupil dividing unit 3 obtained from the information unit 21, the characteristic information of the photographing optical system 20, and the information on the photometric system of the photometric unit 27 itself.

In particular, when a polymer-dispersed liquid crystal described later is used as the pupil dividing means 3, the light cannot be completely shielded even in the light-shielded state, and a scattered light component exists. Therefore,
It is necessary to ensure sufficient matching with the characteristics of the pupil dividing means 3 (such as the luminance at the time of light blocking). In such a case, if the pupil dividing means 3 and the photometric means 27 are incorporated in the camera body 1 side, the data relating to the photometric correction is individually adjusted for each camera body 1 during assembly, so that the pupil dividing means 3 It is also possible to cope with individual variations in characteristics.

FIG. 13 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. The difference between the embodiment shown in FIG. 12 and the embodiment shown in FIG. 13 is that the pupil dividing means 3 also functions as a main mirror. A semi-transparent film is formed on the surface of the pupil dividing means 3, and is configured to reflect a part of the incident light beam to the pentaprism 10.

An advantage of the embodiment shown in FIG. 13 is that since the pupil dividing means 3 also serves as a main mirror, the number of parts is reduced and the cost is reduced. Further, as compared with the case where the pupil dividing means 3 is separately arranged, space efficiency is higher and the camera body 1 can be made smaller. In addition, as a configuration in which the main mirror 13 and the pupil dividing means 3 are used in common, the main mirror 13 may be provided, and the pupil dividing means 3 made of liquid crystal may be arranged on the back side (the shutter 11 side).

FIG. 14 is an explanatory diagram showing a schematic configuration of another variation of the embodiment shown in FIG. FIG.
The difference from the embodiment shown in FIG. 2 is that the pupil dividing means 3 also functions as a sub-mirror. A translucent film is formed on the rear surface of the pupil dividing means 3, and is configured to reflect only the light beam that has passed through the pupil dividing means 3 in the direction of the photoelectric conversion means 4.

An advantage of the embodiment shown in FIG. 14 is that the number of components is reduced and the cost is reduced because the pupil dividing means 3 also serves as a sub-mirror function. Further, compared with the case where the pupil dividing means 3 and the sub-mirror are separately arranged, the space efficiency is higher and the size of the camera body 1 can be reduced. In addition, as a configuration that also serves as the pupil dividing means 3 and the sub mirror, a sub mirror is provided,
The pupil dividing means 3 made of liquid crystal may be provided on the front surface of the sub mirror.

FIG. 15 is an explanatory diagram showing a schematic configuration of another variation of the embodiment shown in FIG. FIG.
The difference from the embodiment shown in FIG. 2 is that the pupil splitting means 3 is not located in the optical path to the primary image plane (the surface of the film 12), but a relay optical system (condenser lens 22, pupil splitting means 3, re-imaging). (Consisting of lens 23 etc.) in the optical path of the re-imaging optical system.

In FIG. 15, the condenser lens 22 is disposed in the optical path turned back by the sub mirror 14. Further, the pupil dividing means 3 is arranged on the front surface or the rear surface of the re-imaging lens 23. Further, the photoelectric conversion unit 4 is arranged near a secondary image plane formed by the re-imaging lens 23. An advantage of the embodiment shown in FIG. 15 is that since the pupil dividing means 3 does not exist in the photographing optical path or the observation optical path, it is possible to prevent the light quantity and the image quality from lowering.

Further, since the pupil dividing means 3 is arranged in the re-imaging optical system having a narrow optical path, the pupil dividing means 3 can be reduced in size as compared with the case where it is arranged in the photographing optical path. is there. FIG. 16 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. The difference from the embodiment shown in FIG. 15 is that the relay optical system is disposed not in the optical path passing through the main mirror 13 and the sub-mirror 14 but in the observation optical system reflected by the main mirror 13. .

In FIG. 16, the lower surface 24 of the pentaprism 10 has a condenser lens function. The roof surface 25 of the pentaprism 10 is translucent,
The re-imaging lens 23 is provided in the optical path passing through the roof surface 25. Then, the pupil dividing means 3 includes the re-imaging lens 2
3 (located on the front surface in the example of FIG. 16), and the photoelectric conversion unit 4 is disposed near the secondary image plane formed by the re-imaging lens 23.

An advantage of the embodiment shown in FIG. 16 is that since the pupil dividing means 3 does not exist in the photographing optical path, it is possible to prevent a decrease in photographing light amount and image quality. Further, since the pupil dividing means 3 is disposed in the re-imaging optical system having a narrow optical path, the pupil dividing means 3 can be reduced in size.

Further, since the re-imaging optical system is arranged in the observation optical system, the main mirror 13 may be a simple reflecting mirror.
The submirror is no longer needed. FIG. 17 is an explanatory diagram showing a schematic configuration of an embodiment in which the focus detection device according to the present invention is applied to an electronic viewfinder type silver halide camera. As shown in FIG. 17, the electronic viewfinder type silver halide camera includes a camera body 1 and an interchangeable lens structure 2.

As shown, the interchangeable lens structure 2 includes a photographing optical system 20, pupil dividing means 3 arranged near the exit pupil position of the photographing optical system 20, and information on the photographing optical system 20 and the pupil dividing means 3. And information means 21 for outputting the information to the outside. In the embodiment shown in FIG. 17, the pupil dividing means 3 is arranged in the optical path of the photographing optical system 20. The camera body 1 has a shutter 11 as shown in FIG.
A film 12, a mirror for polarizing the light beam from the photographing optical system 20, a main mirror 13 that is retracted from the photographing optical path during photographing, and a reduction optical system 17 that reduces and forms an image of the light beam that has passed through the main mirror 13. , A photoelectric conversion unit 4 including a two-dimensional CCD sensor or the like disposed on the image forming plane of the reduction optical system 17, a pupil division unit 3, and a photoelectric conversion unit 4.
While controlling the operation of (1), receiving the signal from the photoelectric conversion means 4 and calculating the image shift amount based on the signal,
An arithmetic control unit 5 for detecting a defocus amount of the photographing optical system 20 based on the calculated image shift amount and information from the information unit 21, and a photoelectric conversion unit 4 incorporated in the arithmetic control unit 5.
And a viewing optical system 19 provided for observing the display screen of the display means 18.

An advantage of the embodiment shown in FIG. 17 is that since the photoelectric conversion means 4 receives an image of the reduction optical system 17, the photoelectric conversion means 4 has a smaller area as compared with an image pickup device used in an electronic camera. The ability to use area sensors. Further, the output signal of the photoelectric conversion means 4 can be used not only for focus detection but also as an image signal to be displayed on the display means 18.

Further, as compared with the optical viewfinder shown in FIG. 5, since the electronic viewfinder is employed, the camera body 1 can be reduced in size. Also, the main mirror 13
Means that a simple reflecting mirror is sufficient and a sub-mirror is not required. FIG. 18 is an explanatory diagram showing a schematic configuration when the embodiment shown in FIG. 17 is applied to an electronic camera. The difference from the embodiment shown in FIG.
1 in that an image pickup means 15 and a storage means 16 for storing image signals output from the image pickup means 15 are provided in place of the film 1 and the film 12.

An advantage of the embodiment shown in FIG. 18 is that since the photoelectric conversion means 4 receives an image of the reduction optical system 17, an area sensor having a smaller area than that of the imaging means 15 can be used. Further, the main mirror 13 can be used as a shutter of the imaging unit 15. Also, the output signal of the focus detection photoelectric conversion means 4 can be used as an image signal for display.

Further, since the image pickup means 15 is not used for displaying an image, it is not necessary to constantly drive the image pickup means 15 having a larger number of pixels as compared with the photoelectric conversion means 4, so that power consumption can be reduced. FIG. 19 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG.

The difference from the embodiment shown in FIG. 18 is that the signal of the image pickup means 15 taken in the storage means 16 is displayed as an image on the display means 18, and the image is displayed on the observation optical system 19.
Is the point to be observed. Further, the main mirror 13 is a half mirror, and there is no need to evacuate from the optical path even during photographing. An advantage of the embodiment shown in FIG. 19 is that a signal of the imaging means 15 is used as a display screen and observed by the observation optical system 19, so that a high-quality screen can be observed.

Further, since a mechanism for retracting the main mirror 13 is not required, the mechanism of the camera can be simplified. FIG. 20 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. The difference from the embodiment shown in FIG. 19 is that the pupil dividing means 3 is built in the camera body 1 instead of the interchangeable lens structure 2. That is, the embodiment shown in FIG. 20 is an electronic camera version of the embodiment shown in FIG.

As shown, the pupil dividing means 3 includes a photographing optical system 20 and a main mirror 1 in the camera body 1.
3 in the light path. Further, the main mirror 13 is constituted by a half mirror, the imaging means 15 is arranged in the optical path deflected by the main mirror 13, and the photoelectric conversion means 4 receives the light beam passing through the main mirror 13.

An advantage of the embodiment shown in FIG. 20 is that the position of the pupil dividing means 3 becomes constant irrespective of the interchangeable lens, and the focus detection accuracy is stabilized. Also, the interchangeable lens structure 2
Since it is not necessary to incorporate the pupil division means 3 for each time, the cost of the interchangeable lens can be reduced. Further, since the pupil dividing means 3 is not built in the interchangeable lens structure 2, the focus can be detected even with a conventional interchangeable lens.

Since the pupil dividing means 3 and the arithmetic control means 5 are built in the camera body 1 and the pupil dividing means 3 and the arithmetic control means 5 are fixed, the interchangeable lens structure 2
As compared with the case where the pupil dividing means 3 is incorporated in the camera, the complexity of the control operation can be reduced, and the operation of the pupil dividing means 3 can be optimized. Specifically, when the pupil division means 3 is provided in the interchangeable lens structure 2, it is difficult to match a large number of pupil division means 3 having different characteristics with the arithmetic control means 5. However, by providing the pupil division means 3 in the camera body 1, only the matching between one pupil division means and the arithmetic control means 5 needs to be considered, so that there is an advantage that adjustment at the time of assembling becomes easy. When the pupil dividing means 3 is provided in the interchangeable lens structure 2, it is necessary to store information on the pupil dividing means 3 in the information means 21. However, providing the pupil division means 3 in the camera body 1 eliminates the need for the information means 21 to store information about the pupil division means 3.

If the main mirror 13 is of a retractable type as a normal mirror, the main mirror 13 can be
Can also be used as a shutter. FIG.
FIG. 20 is an explanatory diagram showing a schematic configuration of another variation of the embodiment shown in FIG. 19. As shown, the difference from the embodiment shown in FIG. 19 is that the pupil dividing means 3 is built in the camera body 1 instead of the interchangeable lens structure 2.

In FIG. 21, a signal from the imaging means 15 is fetched into the storage means 16, and the signal is displayed as an image on the display means 18. This image is displayed on the observation optical system 19.
Observed by Further, the main mirror 13 is a half mirror, and there is no need to evacuate from the optical path even during photographing. The advantage of the embodiment shown in FIG.
Is constant regardless of the interchangeable lens structure 2, and the focus detection accuracy is stabilized.

Since the interchangeable lens structure 2 does not need to incorporate the pupil dividing means 3, the cost of the interchangeable lens structure 2 can be reduced. Further, since the pupil dividing means 3 is not built in the interchangeable lens structure 2, the focus can be detected even with a conventional interchangeable lens. Since the pupil dividing means 3 and the arithmetic control means 5 are built in the camera body 1, the pupil dividing means 3 and the arithmetic control means 5 are fixed, so that the pupil dividing means 3 is built in the interchangeable lens structure 2. In this case, the complexity of the control operation can be reduced as compared with the case where the pupil division means 3 is optimized.

Specifically, when the pupil dividing means 3 is provided in the interchangeable lens structure 2, it is difficult to match a large number of pupil dividing means 3 having different characteristics with the arithmetic control means 5. However, by providing the pupil division means 3 in the camera body 1, only the matching between one pupil division means and the arithmetic control means 5 needs to be considered, so that there is an advantage that adjustment at the time of assembling becomes easy. When the pupil dividing means 3 is provided in the interchangeable lens structure 2, it is necessary to store information on the pupil dividing means 3 in the information means 21. However, providing the pupil division means 3 in the camera body 1 eliminates the need for the information means 21 to store information about the pupil division means 3.

Further, since the signal output from the image pickup means 15 is displayed on the screen, high quality observation is possible. Further, since a mechanism for retracting the main mirror 13 is not required, the mechanism of the camera can be simplified. FIG. 22 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. The difference from the embodiment shown in FIG. 21 is that the pupil dividing means 3 also functions as a main mirror.

As shown, the pupil dividing means 3 includes a liquid crystal 3a having a plurality of apertures near a position where the light beam from the photographing optical system is irradiated. Further, on the back surface of the pupil dividing means 3, a full transmission mirror 3b and a half mirror 3c are provided. The position where the half mirror 3c is provided corresponds to the position where the liquid crystal 3a is provided. Due to the above configuration, light from the aperture selectively controlled by the pupil division unit 3 reaches the photoelectric conversion unit 4.

An advantage of the embodiment shown in FIG. 22 is that the number of components is reduced and the cost is reduced because the pupil dividing means 3 also serves as a main mirror function.
Further, compared with the case where the pupil dividing means 3 is separately arranged,
That is, the space efficiency is high, and the size of the camera body 1 is reduced. FIG. 23 is an explanatory diagram showing a schematic configuration of another variation of the embodiment shown in FIG. The difference from the embodiment shown in FIG. 21 is that the pupil dividing means 3 is not in the optical path up to the surface of the imaging means 15 but the main mirror 1
3 is disposed in the optical path of the re-imaging optical system using the relay optical system deflected by the optical system. Here, the re-imaging optical system is an optical system including the re-imaging lens 23 and the condenser lens 22. Further, the main mirror 13 is constituted by a half mirror.

In FIG. 23, a condenser lens 22 is arranged near the primary image plane in the optical path deflected by the main mirror 13. Further, the pupil dividing means 3 is arranged on the front surface or the rear surface of the re-imaging lens 23. Further, the photoelectric conversion unit 4 is arranged near a secondary image plane formed by the re-imaging lens 23. An advantage of the embodiment shown in FIG. 23 is that since the pupil dividing means 3 does not exist in the photographing optical path, it is possible to prevent a decrease in light amount and image quality.

Since the pupil dividing means 3 is arranged in the re-imaging optical system, the pupil dividing means 3 can be downsized. FIG. 24 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. The difference from the embodiment shown in FIG. 23 is that the pupil division means 3 and the photoelectric conversion means 4
And the arithmetic control means 5 are all incorporated in the interchangeable lens structure 2. In addition, the arithmetic and control means 5 transmits the information means (2
It has the function of 1).

According to the embodiment shown in FIG. 24, the half mirror 26 is arranged in the middle of the photographing optical system 20,
A part of the photographing light beam is deflected. As shown in the figure, a pupil dividing unit 3, a reduction optical system 17, and a photoelectric conversion unit 4 are arranged in an optical path deflected by the half mirror 26. The photoelectric conversion unit 4 is arranged on the image forming plane of the reduction optical system 17.

The advantage of the embodiment shown in FIG. 24 is that the configuration used for focus detection (pupil division means 3, photoelectric conversion means 4,
Since all of the arithmetic control means 5) are built in the interchangeable lens structure 2, the focus can be detected even when the camera is mounted on a normal camera body. FIG. 25 is an explanatory diagram showing a schematic configuration when the embodiment shown in FIG. 19 is applied to a lens-integrated electronic camera. The difference from the embodiment shown in FIG. 19 is that the photoelectric conversion means 4 for focus detection and the image pickup means (15) are also used.

The operation of the photoelectric conversion means 4 is controlled by the arithmetic and control means 5, and its output signal is sent to the arithmetic and control means 5 and the storage means 16. The advantage of the embodiment shown in FIG.
By using the photoelectric conversion means 4 for focus detection and the imaging means together, the cost of the system can be reduced.
Also, by integrating the camera body and lens,
The photographic optical system can be specified, the configuration and operation of the pupil dividing means 3 can be optimized, and more accurate focus detection can be performed.

FIG. 26 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. The difference from the embodiment shown in FIG. 22 is that the photoelectric conversion unit 4 and the image pickup unit (15) are also used. Pupil dividing means 3
Has a liquid crystal on the surface thereof, and reflects an image of an aperture which is alternately switched to the photoelectric conversion means 4.

An advantage of the embodiment shown in FIG. 26 is that the system can be reduced in cost by using the photoelectric conversion means 4 for focus detection and the imaging means. Further, by arranging the photoelectric conversion unit 4 in the optical path deflected by the pupil division unit 3 and also using the imaging unit, the size of the camera body 1 in the optical axis direction can be reduced, and the camera body can be downsized. Becomes

(Another Example of Liquid Crystal Shutter) FIGS. 27A and 27B are diagrams showing another example of the liquid crystal used for the liquid crystal shutter constituting the pupil division means 3. FIG. FIG. 8 described above.
The liquid crystal shutters shown in (a) and (b) of FIG.
It uses N (TWISTED NEMATIC) liquid crystal. However, FIGS. 27A and 27B show an example in which the pupil dividing means 3 is constituted by a liquid crystal shutter using a GH (GUEST HOST) liquid crystal.

27A and 27B, the liquid crystal molecules 30 are sandwiched between the glass substrates 31 so that the alignment direction is twisted, and the dichroic dye molecules 37 are aligned along with the liquid crystal molecules. . A transparent electrode 32 is formed on the inner surface of a glass substrate 31, and a voltage is applied to the transparent electrode 32 by a power supply 35 and a switch 36. The dichroic dye molecules 37 have a property of not absorbing light incident perpendicular to the molecular axis.

Therefore, as shown in FIG. 27A, when no voltage is applied between the transparent electrodes 32, the incident light is blocked and blocked by the dichroic dye molecules 37 oriented in various directions. . As shown in FIG. 27B, when a voltage is applied between the transparent electrodes 32, the liquid crystal molecules 30 are oriented in a direction perpendicular to the transparent electrodes, and the dichroic dye molecules 37 are also moved to the transparent electrodes. Since the light is oriented in the vertical direction, the incident light passes through the dichroic dye molecule 37 without being absorbed.

An advantage of forming the pupil dividing means 3 using GH liquid crystal is that the structure of the device is simplified because no polarizing plate is used. (A) and (b) of FIG.
FIG. 9 is a diagram showing another example of the liquid crystal used for the liquid crystal shutter constituting the pupil division means 3. FIGS. 28A and 28B show an example in which the pupil dividing means 3 is constituted by a liquid crystal shutter using polymer dispersed liquid crystal.

28 (a) and (b), liquid crystal particles 38 dispersed in a polymer are sandwiched between glass substrates 31, a transparent electrode 32 is formed on the inner surface of the glass substrate 31, and a power source 35 is provided. And the switch 36, the transparent electrode 3
2 is configured to apply a voltage. As shown in FIG. 28A, when no voltage is applied between the transparent electrodes 32, the liquid crystal molecules are oriented in different directions within the liquid crystal particles 38 dispersed in the polymer. Therefore, scattering occurs at the interface between the liquid crystal particle 38 and the polymer due to the difference in the refractive index between the liquid crystal particle 38 and the polymer, and the incident light is shielded.

As shown in FIG. 28B, the transparent electrode 3
When a voltage is applied between the two, the orientation direction of the liquid crystal molecules is uniform in the liquid crystal particles 38 dispersed in the polymer, and the refractive indices of the liquid crystal and the polymer are equal, so that the incident light passes through without being scattered. The advantage of forming the pupil dividing means 3 using the polymer dispersed liquid crystal is that the transmittance of the light beam is improved as compared with the case where the TN liquid crystal or the GH liquid crystal is used, since the polarizing plate and the dye are not used.

The rise and fall characteristics at the time of voltage on / off are superior to TN liquid crystal and GH liquid crystal.
A high-speed pupil division operation (opening and closing operation of the aperture) is made possible. In the case where a pupil dividing unit is formed using a TN liquid crystal or a GH liquid crystal, a step of aligning the liquid crystal with respect to the glass substrate is required. However, in the case where the pupil dividing means is formed by using the polymer dispersed liquid crystal, the above steps are not required, so that the number of assembling steps can be reduced and the cost can be reduced.

Further, in the case of the liquid crystal shutter using the polymer dispersed liquid crystal shown in FIG. 28, the liquid crystal shutter becomes transparent when a voltage is applied, and becomes light-shielded when no voltage is applied. However, by using the reverse-type polymer-dispersed liquid crystal, a light-shielding state can be obtained when a voltage is applied, and a transparent state can be obtained when no voltage is applied. For example, the reverse type polymer-dispersed liquid crystal disclosed in the following document has the same refractive index between the liquid crystal and the polymer when no voltage is applied and becomes transparent, and when no voltage is applied, a difference in refraction between the liquid crystal and the polymer occurs. It is configured to be in a light shielding state.

Rumiko Yamaguti et
al. Jpn. J. Appl. Phys. Vo1.36
(1998) pp. 2771-2774, Part 1, No. 5A. May, 1997 Reverse Mode and Wide View
winlg Angle Properties in Polymer Dis
persed Liquid Cells Prepared Usi
nga UV Curable Liquid Crystal (Lumiko Yamaguchi et al., JP NJ PLP L.P. H.C. And wide viewing angle Properties in polymer dispersed liquid cells Prepared using a you buoyable liquid crystal) The advantage of using a liquid crystal shutter with the above-mentioned reverse type liquid crystal is that light is transmitted when no voltage is applied, so it can be used for cameras and the like. When applied, observation with a finder or the like becomes possible even when the power is turned off.

(Removal of Vignetting Effect) When focus detection is performed at a position outside the optical axis of the screen, vignetting occurs due to a lens outer diameter other than the aperture. FIG. 29 is an explanatory diagram illustrating an example in which vignetting occurs due to the lens outer diameter of the photographing optical system. The optical system shown in FIG. 29 includes an image forming plane 60, an optical axis 61, an imaging stop 62, and an outer diameter 63 of a lens constituting the imaging optical system.

As shown in the figure, at the point 64 on the optical axis, the vignetting of the light beam does not occur except at the photographing stop 62. However, at a point 65 off the optical axis, as shown in FIG. 30, vignetting occurs due to vignetting of the light beam. That is, in FIG. 30, only the light beam passing through the overlapping portion 66 of the outer diameter 63 of the lens forming the shadowing optical system with the photographing stop 62 reaches the point 65 off the optical axis shown in FIG.

Therefore, when focus detection is performed at a point outside the optical axis, simply switching the aperture symmetrical with respect to the optical axis may result in an unsatisfactory light quantity of a pair of light beams used for focus detection due to the vignetting. The balance becomes worse, and the focus detection accuracy deteriorates. When vignetting is large, a light beam passing through one of the openings is completely vignetted, and focus detection becomes impossible.

Next, the structure and operation of the pupil dividing means 3 for preventing the effect of vignetting will be described with reference to FIGS. 31 to 61. FIG. 31 is a diagram showing a first specific example of the pupil dividing means 3 for preventing the light amount imbalance of the pair of light beams caused by vignetting. As shown in FIG. 31, the pupil dividing means 3 also serves as the photographing aperture 62. Further, the plurality of elliptical openings 67 are configured to be able to independently control light shielding and light transmission. The elliptical openings 67 are densely arranged on the pupil plane. In FIG. 31, the image shift detection direction for focus detection is set in the short axis direction (horizontal direction in the drawing) of the elliptical shape.

When the focus detection position is on the optical axis, as shown in FIG.
69 is alternately switched. When the focus detection position is off the optical axis (when vignetting occurs in the image shift detection direction), as shown in FIG. 33, the focus detection position is arranged symmetrically with respect to the center of the overlapping portion 66 due to vignetting in the image shift detection direction. The openings 70 and 71 are alternately switched.

When the focus detection position is off the optical axis (when vignetting occurs in a direction perpendicular to the image shift detection direction), as shown in FIG. Openings 72, 7 which are symmetrical and aligned in the image shift detection direction.
3 is alternately switched. The vignetting state is configured to be identified by the arithmetic and control unit 5 based on information obtained from the information unit 21.

The advantage of the pupil dividing means 3 shown in FIG. 31 is that, by switching and using a plurality of apertures according to the state of vignetting, vignetting of the focus detection light beam is eliminated, and the focus detection accuracy is reduced due to vignetting. The purpose is to prevent focus detection from becoming impossible. FIG. 35 is a diagram showing a second specific example of the pupil division means 3 for preventing the light quantity imbalance of the pair of light beams caused by vignetting. As shown in FIG. 35, the pupil dividing means 3 also serves as the photographing aperture 62. The plurality of hexagonal openings 74 are configured to be able to independently control light shielding and light transmission. The elliptical openings 74 are densely arranged on the pupil plane. In FIG. 35, the image shift detection direction for focus detection is set to the horizontal direction.

When the focus detection position is on the optical axis, it is symmetric with respect to the optical axis of the pupil dividing means 3, as shown in FIG.
Therefore, as shown, the openings 75 and 76 formed from the plurality of openings are alternately switched. When the focus detection position is off the optical axis (when vignetting occurs in the image shift detection direction), the aperture is controlled as follows. That is, FIG.
As shown in (2), openings 77 and 78 formed from a plurality of openings symmetric with respect to the center of the overlapping portion 66 due to vignetting and arranged in the image shift detection direction are alternately switched.

When the focus detection position is off the optical axis (when vignetting occurs in a direction perpendicular to the image shift detection direction), the aperture is controlled as follows. That is, as shown in FIG. 38, openings 79 and 80 formed by a plurality of openings symmetric with respect to the center of the overlapping portion 66 due to vignetting and arranged in the image shift detection direction are alternately switched. The advantage of the pupil splitting means 3 shown in FIG. 35 is that, by switching and using a plurality of apertures according to the state of vignetting, vignetting of the focus detection light beam is eliminated, and the focus detection accuracy is reduced due to vignetting and focus detection is performed. It is to prevent becoming impossible.

Further, by employing a hexagonal aperture, a plurality of apertures can be efficiently arranged on the pupil plane. In addition, by forming an opening by combining a plurality of hexagonal openings, the opening shape can be set flexibly for vignetting. Further, by forming an opening by combining a plurality of hexagonal openings, the amount of light used for focus detection can be increased. Therefore, the luminance that is the limit of focus detection can be set to a low value.

FIG. 39 is a diagram showing a third specific example of the pupil division means 3 for preventing the light quantity imbalance of a pair of light beams due to vignetting. As shown in FIG.
Also serves as the photographing aperture 62. The plurality of square openings 81 are configured to be able to independently control light shielding and light transmission. The square openings 81 are densely arranged on the pupil plane. In FIG. 35, the image shift detection directions for focus detection are the horizontal direction, the vertical direction,
The angle direction is set to 45 degrees leftward (four directions).

FIG. 40 shows the structure of the photoelectric conversion means 4 used in combination with the pupil division means 3 shown in FIG. As shown in FIG. 40, the shape of the pixel 92 is a square, and the pixel pitch is set substantially the same in the horizontal and vertical directions. When the image shift detection direction is set to the horizontal direction, a set of pixels 92 in the horizontal direction in FIG. 40 is used for focus detection. When the image shift detection direction is set to the vertical direction, the pixel 9 in the vertical direction in FIG.
Two sets are used for focus detection. Image shift detection direction is 45
When set in the degree direction, a set of pixels 92 in the 45 degree direction in FIG. 40 is used for focus detection.

When the focus detection position is on the optical axis, as shown in FIG. 41 and FIG. 42, the openings 82 and 83 arranged symmetrically on the optical axis of the pupil dividing means 3 and arranged in the horizontal direction or in the vertical direction. The aligned openings 84 and 85 are alternately switched. In this case, the focus detection using the openings 82 and 83 arranged in the horizontal direction and the focus detection using the openings 84 and 85 arranged in the vertical direction may be used together. Further, focus detection is performed using one of the focus detection using the openings 82 and 83 and the focus detection using the openings 84 and 85 arranged in the vertical direction. May be switched.

When the focus detection position is off the optical axis (when vignetting occurs in the horizontal direction in the drawing), as shown in FIG.
The openings 86a, 87a that are symmetric with respect to the center of the overlapping portion 66 due to vignetting and are arranged in the horizontal direction in the drawing are alternately switched. At this time, the image shift detection direction is set to the horizontal direction, and a set of pixels 92 in the horizontal direction shown in FIG. 40 is used for focus detection.

When the focus detection position is off the optical axis (when vignetting occurs in the horizontal direction of the drawing), as shown in FIG. The openings 86b and 87b arranged in the vertical direction in the drawing may be alternately switched. In that case, the image shift detection direction is set in the vertical direction, and the pixel 92 in the vertical direction in FIG.
Are used for focus detection.

When the focus detection position is off the optical axis (when vignetting occurs in the direction perpendicular to the drawing), as shown in FIG. 44, it is symmetrical with respect to the center of the overlapped portion 66 due to vignetting. The openings 88 and 89 arranged in the horizontal direction are alternately switched. At this time, the image shift detection direction is set in the horizontal direction, and a set of pixels 92 in the horizontal direction in FIG. 40 is used for focus detection.

When the focus detection position is off the optical axis (when vignetting occurs in the direction of 45 degrees which rises to the right in the drawing), FIG.
As shown in FIG. 5, the openings 9 are symmetrical with respect to the center of the overlapping portion 66 due to vignetting, and are aligned in the direction of 45 degrees ascending left in the drawing.
0 and 91 are alternately switched. At this time, the image shift detection direction is set to the 45 ° leftward upward direction, and a set of pixels 92 in the 45 ° upward leftward direction in FIG. 40 is used for focus detection.

An advantage of the pupil division means 3 shown in FIG. 39 is that by forming the pupil division means 3 from a plurality of square openings, image shift detection in four directions becomes possible. Also, the direction in which the apertures are arranged and the direction of the pixel set are set so that image shift detection is performed in a direction perpendicular to the direction in which vignetting occurs (the direction connecting the point on the optical axis and the focus detection position). By doing so, the identity of the pair of focus detection light beams is secured,
It is an object of the present invention to prevent a decrease in focus detection accuracy due to asymmetrical aberration of a photographing optical system.

FIG. 46 is a diagram showing a fourth specific example of the pupil dividing means 3 for preventing the light quantity imbalance of a pair of light beams due to vignetting. As shown in FIG.
Also serves as the photographing aperture 62. Pupil dividing means 3
Are formed by a plurality of fan-shaped openings 93 divided by radial boundaries passing through the optical axis. And
Each fan-shaped opening 93 can independently control light shielding and light transmission. In this embodiment, the boundary is horizontal,
The radiation is formed in the vertical direction, rising 45 degrees to the right, and rising 45 degrees to the left. In FIG. 46, the image shift detection directions for focus detection are horizontal, vertical, and right 45 degrees.
The direction is set to four directions, that is, a degree direction and a left 45 degree direction.
The pupil dividing means 3 shown in FIG. 46 is used in combination with the photoelectric conversion means 4 shown in FIG.

As shown in FIG. 47, when the focus detection position is on the optical axis, the two openings 94 and 95 divided by the vertical boundary are alternately switched. As shown in FIG. 48, when the focus detection position is off the optical axis (when vignetting occurs in the vertical direction in the drawing), the focus detection position is shifted in the vertical direction so as to be symmetric with respect to the center of the overlapping portion 66 due to vignetting. The two openings 94 and 95 divided by the boundary line are alternately switched. At this time, the image shift detection direction is set to the horizontal direction, and the photoelectric conversion unit 4 shown in FIG.
Two sets are used for focus detection.

As shown in FIG. 49, when the focus detection position is off the optical axis (when vignetting occurs in the horizontal direction in the drawing).
Alternately switches the two openings 96 and 97 divided by the horizontal boundary line so as to be symmetric with respect to the center of the overlapping portion 66 due to vignetting. At this time, the image shift detection direction is set to the vertical direction, and the photoelectric conversion unit 4 shown in FIG.
, A set of pixels 92 in the vertical direction is used for focus detection.

As shown in FIG. 50, when the focus detection position is off the optical axis (when vignetting occurs in the 45 ° direction rising to the right in the drawing), the center of the overlapping portion 66 due to vignetting is determined. The two openings 98 and 99 divided by the boundary line in the 45-degree upward direction are alternately switched so as to be symmetrical. At this time, the image shift detection direction is set to the 45-degree left-up direction, and the set of pixels 92 in the 45-degree left-up direction is used for focus detection in the photoelectric conversion unit 4 shown in FIG.

An advantage of the pupil splitting means 3 shown in FIG. 46 is that by forming the pupil splitting means 3 from a plurality of fan-shaped apertures, image shift detection in four directions becomes possible. Also, the direction in which the pupil division apertures are arranged and the direction of the pixel set are set so that image shift detection is performed in a direction perpendicular to the direction in which vignetting occurs (the direction connecting the point on the optical axis and the focus detection position). By setting, the identity of a pair of focus detection light beams is ensured, and a reduction in focus detection accuracy due to the asymmetrical aberration of the imaging optical system can be prevented.

Further, as compared with the embodiment shown in FIG. 39, the number of openings can be reduced, so that the device configuration can be simplified and the operation control can be simplified. Further, even when vignetting occurs, vignetting can be substantially divided into two and used as a light flux for focus detection, so that the low luminance limit of focus detection can be maintained even at a focus detection position off the optical axis.

FIG. 51 is a diagram showing a fifth specific example of the pupil dividing means 3 for preventing the light quantity imbalance of a pair of light beams due to vignetting. As shown in FIG.
Also serves as the photographing aperture 62. Pupil dividing means 3
Is constituted by a plurality of strip-shaped openings 100 divided by a vertical boundary line 101. Each of the strip-shaped openings 100 can independently control light shielding and light transmission. The image shift detection direction for focus detection is set in the horizontal direction in FIG.

As shown in FIG. 52, when the focus detection position is on the optical axis, the two openings 102 and 103 divided left and right by a vertical boundary 101 passing through the optical axis are alternately switched. As shown in FIG. 53, when the focus detection position is off the optical axis (when vignetting occurs in the horizontal direction in the drawing), the focus detection position is symmetrical in the horizontal direction with respect to the center of the overlapping portion 66 due to vignetting. The two openings 105 and 106 divided into right and left by the vertical boundary line 104 are switched alternately.

As shown in FIG. 54, when the focus detection position is further off the optical axis closer to the periphery of the screen (when vignetting occurs in the horizontal direction in the drawing), vignetting further proceeds. In this case, the two openings 108 and 109 divided left and right by the vertical boundary 107 are switched alternately so as to be substantially symmetric in the horizontal direction with respect to the center of the overlapping portion 66 due to vignetting.

The advantage of the pupil dividing means 3 shown in FIG. 51 is that by adjusting the position of the boundary between the two apertures according to the degree of vignetting, vignetting can be almost equally divided and a pair of focus detecting light fluxes can be obtained. That is, it is possible to prevent imbalance in light quantity. FIG. 55 is a diagram showing a sixth specific example of the pupil dividing means 3 for preventing the light amount imbalance of the pair of light beams caused by vignetting. As shown in FIG. 55, the pupil dividing means 3 also serves as the photographing aperture 62. Also, the pupil dividing means 3
The openings 110, 111, and 112 form two elliptical openings that overlap each other and are arranged in the horizontal direction. Each opening 110, 111, 112 is
Light transmission can be controlled independently. The image shift detection direction for focus detection is set in the horizontal direction in FIG.

In the case of performing the focus detection position, FIGS.
As shown in FIG. 7, an elliptical opening constituted by the openings 110 and 112 and an elliptical opening constituted by the openings 111 and 112 are alternately switched. Pupil dividing means 3 shown in FIG.
The advantage of this method is that the amount of light required for focus detection can be ensured by switching the openings that overlap each other in this manner.

In addition, when the focus is detected at a position outside the optical axis, the unbalance of the light amounts of the pair of focus detection light beams due to vignetting can be reduced by overlapping the apertures. FIG. 58 shows that the pupil dividing means 3 is provided with
It is a figure which shows the specific example at the time of comprising with ITAL MICRORROR DEVICE. The DMD is formed as a set of fine mirror structures 120 as shown in FIG.

FIG. 59 is a view showing the fine mirror structure 120. As shown in FIG. The mirror structure 120, as shown,
A mirror 123 is placed on a shaft 122 formed on a substrate 121.
Are formed by a semiconductor process. Mirror 123
Changes the angle with respect to the axis 122 by applying an electrical control signal. FIGS. 60 and 61 are diagrams showing an example of the operation of the pupil dividing means 3 formed by the DMD.
As shown in FIG. 60, pupil dividing means 3 formed by DMD
Is divided into two portions 124 and 125, and the two portions 124 and 125 constitute a pair of openings.

The pupil dividing means 3 is arranged in the photographing optical path.
It has a function of deflecting a light beam for focus detection. FIG.
As shown in FIG. 1, when the mirror 123 is controlled in parallel with the substrate 121, the reflected light flux is deflected in the direction of the photoelectric conversion means 4. In addition, the mirror 123
When the light flux is controlled to be non-parallel to 1, the reflected light flux is deflected in a direction other than the photoelectric conversion means 4. Therefore, by alternately controlling the mirrors 123 of the two parts 124 and 125, the light reflected by the part 124 and
The light reflected by the portion 125 is alternately received by the photoelectric conversion unit 4.

The advantage of forming the pupil dividing means 3 by a DMD is that the operating characteristics of the DMD are higher than those of the liquid crystal,
The point is that the aperture can be switched very quickly. In the above description, as shown in FIG. 60, the DMD is divided into two portions 124 and 125, but it goes without saying that there are various methods for dividing.

(Other Configuration of Photoelectric Conversion Means 4) FIG.
FIG. 7 is a partially enlarged view showing another example in which the photoelectric conversion unit 4 is configured by a two-dimensional CCD sensor. In the two-dimensional CCD sensor shown in FIG. 10, the gates 52, 53, 56, the charge storage units 54, 55,
A CCD charge transfer unit 57 is provided. However, FIG.
In the two-dimensional CCD sensor shown in FIG.
, Gates 152 and 156 and gate 1 on both sides
53, 158, the charge storage unit 154 and the charge storage unit 155,
A CCD charge transfer unit 157 and a CCD charge transfer unit 159 are arranged. The array of the photoelectric conversion pixels 151 of the photoelectric conversion unit 4 is a two-dimensional CC shown in FIG.
Same as D sensor.

According to the two-dimensional CCD sensor shown in FIG. 62, for one pixel, gates 1 arranged on both sides of the pixel are used.
52, 153 and charge storage units 154, 155 are provided. Therefore, when the openings are switched, by switching the gates 152 and 153, charges corresponding to the images formed by the different openings can be stored in the separate charge storage units 154 and 155.

The operation of the photoelectric conversion means 4 shown in FIG. 62 is as follows. The photoelectric conversion pixel 151 generates a charge according to the amount of incident light. Before charge accumulation, gates 152 and 1
53 is closed, and the generated charges are discarded to a drain (not shown). Gates 152 and 153 open and close alternately during charge accumulation. As a result, the gate 152
The charges generated in the photoelectric conversion pixels 151 while the pixel is open are stored in the charge storage unit 154. Gate 15
The charge generated in the photoelectric conversion pixel 151 while the pixel 3 is open is stored in the charge storage unit 155. Gate 15 during this time
6,158 is closed.

When the charge accumulation is completed, the gates 152, 15
3 is closed, and then the gates 156 and 158 are opened. As a result, the charges stored in the charge storage unit 154 and the charge storage unit 155 are transferred to the CCD charge transfer units 157 and 159, respectively.
Then, the data is transferred according to the operation clock of the CCD, and is output to the outside as an electric signal. The advantage of the photoelectric conversion unit 4 shown in FIG. 62 is that the size of the charge storage unit can be increased by providing the charge storage units on both sides of the pixel as compared with the structure of the two-dimensional CCD sensor shown in FIG. That is, the charge amount can be increased, and the dynamic range of the output signal can be expanded.

Further, even in the case of the same pixel size, FIG.
Since the size of the gate and the charge storage portion is larger than that of the structure shown in FIG. 1, the semiconductor process is easy and the production yield is good. The CCD charge transfer units 57 and 59
Is shared with a photoelectric conversion pixel row (not shown) (upper and lower photoelectric conversion pixel rows in FIG. 62), whereby the aperture efficiency of the pixel can be improved.

FIG. 63 is a schematic diagram showing a specific example in which the photoelectric conversion means 4 is constructed using two two-dimensional CCD sensors. In general, in a two-dimensional CCD sensor, a gap in pixel sensitivity is small in a pixel row in a direction along a CCD charge transfer unit. In a two-dimensional CCD sensor, a gap is large in a pixel row in a direction perpendicular to a direction along a CCD charge transfer section because a charge storage section, a gate, and a CCD transfer section are present. Therefore, the focus detection accuracy is improved when the pixel array in the direction along the CCD charge transfer unit is used. Therefore, it is desirable to perform the image shift detection in this direction.

Therefore, it is possible to divide the opening of the pupil dividing means 3 into two directions such as the horizontal direction and the vertical direction (see the pupil dividing means 3 shown in FIG. 39), and the horizontal and vertical directions of the screen are different. When image shift detection is performed in two directions, by providing a two-dimensional CCD sensor in which pixel rows are aligned in each direction, it is possible to provide a focus detection device capable of detecting image shift in two directions with high accuracy.

The configuration shown in FIG. 63 shows, for example, a portion to be replaced by the photoelectric conversion means 4 in the embodiment shown in FIG. That is, the main mirror 1 shown in FIG.
In the optical path having passed through the half mirror 12, the half mirror 12 shown in FIG.
8 are arranged, and the light beam is split into two. Then, two photoelectric conversion units 126 and 127 are provided on the image forming surface in the divided optical path.
Is arranged.

In FIG. 63, the direction of the pixel row of the photoelectric conversion means 126 is the direction of the arrow X (horizontal direction in the plane of the paper), and is used when the direction of detecting the image shift is the direction of the arrow X. Similarly, the direction of the pixel column of the photoelectric conversion unit 127 is the direction Z (the direction perpendicular to the plane of the paper), and the detection direction of the image shift is Z
Used for direction.

FIG. 64 is a block diagram of the photoelectric conversion unit 12 shown in FIG.
It is a top view of No. 6,127. In FIG. 64, on the photoelectric conversion units 126 and 127, the pixel column 129 has a structure in which the gap between pixels is small in the direction of the arrow. Fig. 65
FIG. 66 shows an AGC (AUTOMATIC GAI) when a two-dimensional CCD sensor is used as the photoelectric conversion means 4.
FIG. 4 is an explanatory diagram showing a method of (N CONTROL).

Normally, in the case of a two-dimensional sensor, all pixels are set to the same charge accumulation time. As a result, the output signal level is only optimized for part of the screen, and some parts of the screen are too bright and overflow to exceed the dynamic range, while others are too dark and lack the amount of output signal Or Therefore, when such a two-dimensional sensor is applied to the present invention, accurate focus detection can be performed only on a part of the screen.

Therefore, as shown in FIG. 65, all the pixels arranged two-dimensionally in the photoelectric conversion means 4 are divided into a plurality of blocks 130 (in the figure, nine blocks), and AGC is executed independently. FIG.
Reference numeral 6 denotes a plurality of photoelectric conversion pixels 151 included in one block 130. By applying the AGC method described above to the present invention, the output signal level becomes an appropriate level within the dynamic range in any part of the screen according to the luminance of each block 130 of the screen.

FIG. 67 is a time chart showing the operation timing of the aperture switching in the pupil division means 3 and the charge accumulation in the photoelectric conversion means 4. In the time chart shown in FIG. 11, the aperture of the pupil dividing means 3 and the gate of the photoelectric conversion means 4 are controlled by the signal waveforms shown in FIGS. In practice, the operation of the aperture is shown in FIG.
As shown in the signal waveforms of (a) and (b) of FIG. 7, there is a transition period between ON and OFF. Therefore, if both the opening and closing operation of the opening of the pupil dividing unit 3 and the opening and closing operation of the gate of the photoelectric conversion unit 4 are controlled by the signal waveforms shown in FIGS. 11A and 11B, the electric charge obtained by the photoelectric conversion unit 4 is obtained. Contains many crosstalk components, which adversely affects the detection accuracy of the image shift.

Therefore, as shown in the signal waveforms of FIGS. 67 (c) and (d), the photoelectric conversion means 4 is turned on or off only during the period when the aperture is substantially on or off.
By controlling the gates 52, 53, 152, and 153, the crosstalk component can be reduced.

(Correction of Focus Detection Result) FIGS. 68 and 69
FIG. 8 is a diagram for explaining a method of correcting a focus detection result when the aperture switching operation of the pupil dividing means 3 and the drive for focus adjustment of the photographing optical system are overlapped. Fig. 68
5 is a time chart showing accumulation of charges in the photoelectric conversion means 4, transfer of the accumulated charges from the photoelectric conversion means 4 to the calculation control means 5, and calculation time in the calculation control means 5. That is, FIG. 68 (a) shows a signal waveform in the case where one of the openings is opened to perform the charge accumulation, and the center time of the charge accumulation is T1. FIG. 68 (b) shows a signal waveform in the case where charge accumulation is performed by opening the other opening, and the center time of charge accumulation is T2. FIG. 68 (c) shows the time required to transfer the accumulated charges from the photoelectric conversion means 4 to the arithmetic and control means 5. FIG. 68 (d) shows the time required for performing image shift detection calculation based on the signal taken into the calculation control means 5 and finally calculating the drive amount of the photographing optical system for focus adjustment. At the time T3
To end.

FIG. 69 is a diagram showing the relationship between the lens position of the photographing optical system and the driving time. That is, the photographing optical system is driven to the in-focus position based on the previous instruction of the arithmetic control unit 5, and is located at the position P1 at the time T1, the position P2 at the time T2, and the position P3 at the time T3. Therefore, the photographing optical system moves between the center time T1 when one of the openings is opened to perform the charge accumulation and the center time T2 when the other opening is opened to perform the charge accumulation. When the photographing optical system moves, an image shift occurs by that much, so that it is necessary to correct the focus detection result by the image shift amount. Further, since the photographing optical system is driven even between the center times T1 and T2 at which the charge accumulation is performed and the time T3 at which the calculation is completed, it is necessary to correct the corresponding amount.

The above-described correction of the driving amount is performed as follows. The center time T when one of the openings was opened and charge accumulation was performed
1, the position P1 of the photographing optical system is detected. Next, the position P2 of the imaging optical system at the time T2 when the other opening is opened to perform the charge accumulation is detected. Then, the following equation (9)
The average position P4 of the positions P1 and P2 indicated by is set as the representative position at the time of the charge accumulation.

P4 = (P1 + P2) / 2 (9) At time T3, assuming that the driving amount calculated by the arithmetic control means 5 is S, the moving amount from the charge accumulation time to the end of the arithmetic operation is corrected. The correction drive amount ΔS is calculated by the equation (10). ΔS = S− (P3−P4) (10) Accurate focus detection can be performed by obtaining the correction drive amount ΔS in the arithmetic control unit 5.

[0155]

As is apparent from the above description, according to the first aspect of the present invention, the pupil dividing means includes a plurality of apertures, and selects an optimal divided pupil according to the vignetting state. Since it is used for focus detection, even when focus detection is performed at a position other than the center of the optical axis (position around the screen), focus detection can be performed with high accuracy.

According to the second aspect of the present invention, there is provided a camera provided with a focus detecting device capable of accurately detecting a focus state when a focus is detected at a position other than the center of the optical axis. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing two apertures and photoelectric conversion means provided at an exit pupil position of an imaging optical system.

FIGS. 2A and 2B are explanatory diagrams showing a state where an imaging optical system is in focus.

FIGS. 3A and 3B are explanatory diagrams showing a front focus state in which a focus position of an imaging optical system is located before a focus position.

FIGS. 4A and 4B are explanatory diagrams showing a back focus state in which the focal position of the imaging optical system is located at a position behind the in-focus position.

FIG. 5 is an explanatory view schematically showing a configuration of an embodiment when the focus detection device of the present invention is applied to a single-lens reflex camera.

FIG. 6 is a diagram showing a specific example in which a pupil dividing unit is configured using a liquid crystal shutter.

FIGS. 7A and 7B are explanatory diagrams showing the operation of a pupil dividing unit.

FIGS. 8A and 8B are explanatory diagrams showing a liquid crystal shutter constituting a pupil dividing unit.

FIG. 9 is an explanatory diagram showing an example in which a photoelectric conversion unit is configured by a two-dimensional CCD sensor.

FIG. 10 is a partially enlarged view of the two-dimensional CCD sensor shown in FIG. 9;

FIG. 11 is a diagram showing operation timings of opening switching and charge accumulation.

FIG. 12 is an explanatory view schematically showing a configuration of a variation of the embodiment shown in FIG. 1;

FIG. 13 is an explanatory view schematically showing a configuration of a variation of the embodiment shown in FIG. 12;

FIG. 14 is an explanatory view schematically showing a configuration of another variation of the embodiment shown in FIG. 12;

FIG. 15 is an explanatory diagram showing a schematic configuration of another variation of the embodiment shown in FIG. 12;

FIG. 16 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. 15;

FIG. 17 is an explanatory diagram showing a schematic configuration of an embodiment in which the focus detection device according to the present invention is applied to an electronic viewfinder type silver halide camera.

18 is an explanatory diagram showing a schematic configuration in a case where the embodiment shown in FIG. 17 is applied to an electronic camera.

FIG. 19 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. 18;

FIG. 20 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. 19;

FIG. 21 is an explanatory diagram showing a schematic configuration of another variation of the embodiment shown in FIG. 19;

FIG. 22 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. 21;

FIG. 23 is an explanatory diagram showing a schematic configuration of another variation of the embodiment shown in FIG. 21;

FIG. 24 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. 23;

FIG. 25 is an explanatory diagram showing a schematic configuration in a case where the embodiment shown in FIG. 19 is applied to an electronic camera with an integrated lens.

FIG. 26 is an explanatory diagram showing a schematic configuration of a variation of the embodiment shown in FIG. 22;

FIGS. 27A and 27B are diagrams showing another example of the liquid crystal used for the liquid crystal shutter constituting the pupil dividing means.

FIGS. 28A and 28B are diagrams showing another example of the liquid crystal used for the liquid crystal shutter constituting the pupil dividing means.

FIG. 29 is an explanatory diagram showing an example in which vignetting occurs due to the lens outer diameter of the photographing optical system.

FIG. 30 is an explanatory diagram showing vignetting that occurs due to vignetting due to the lens outer diameter of the photographing optical system.

FIG. 31 is a diagram showing a first specific example of a pupil dividing means for preventing the effect of vignetting.

FIG. 32 is an explanatory diagram showing the operation of the pupil dividing means shown in FIG. 31.

FIG. 33 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 31.

FIG. 34 is an explanatory diagram showing the operation of the pupil division means shown in FIG. 31.

FIG. 35 is a diagram showing a second specific example of the pupil dividing means for preventing the effect of vignetting.

FIG. 36 is an explanatory diagram showing the operation of the pupil dividing means shown in FIG. 35.

FIG. 37 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 35.

FIG. 38 is an explanatory diagram showing the operation of the pupil dividing means shown in FIG. 35.

FIG. 39 is a diagram showing a third specific example of the pupil dividing means 3 for preventing the effect of vignetting.

FIG. 40 is a diagram showing a configuration of a photoelectric conversion unit used in combination with the pupil division unit shown in FIG. 39.

FIG. 41 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 39.

FIG. 42 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 39.

FIG. 43 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 39.

FIG. 44 is an explanatory view showing the operation of the pupil division means shown in FIG. 39.

FIG. 45 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 39.

FIG. 46 is a diagram showing a fourth specific example of the pupil dividing means for preventing the effect of vignetting.

FIG. 47 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 46.

FIG. 48 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 46.

FIG. 49 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 46.

FIG. 50 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 46.

FIG. 51 is a diagram showing a fifth specific example of the pupil dividing means for preventing the effect of vignetting;

FIG. 52 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 51.

FIG. 53 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 51.

FIG. 54 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 51.

FIG. 55 is a diagram showing a sixth specific example of the pupil dividing means for preventing the effect of vignetting.

FIG. 56 is an explanatory view showing the operation of the pupil dividing means shown in FIG. 55.

FIG. 57 is an explanatory diagram showing the operation of the pupil dividing means shown in FIG. 55.

FIG. 58 shows a pupil splitting means using a DMD (DEGITAL MI
FIG. 4 is a diagram showing a specific example in the case of being configured by (RROR DEVICE).

FIG. 59 is a view showing a fine mirror structure in the DMD shown in FIG. 58;

FIG. 60 is a view showing an example of the operation of a pupil division unit formed by a DMD.

FIG. 61 is a diagram showing an example of the operation of a pupil division unit formed by a DMD.

FIG. 62 is a partially enlarged view showing another example in which the photoelectric conversion means is constituted by a two-dimensional CCD sensor.

FIG. 63 is a schematic view showing a specific example in which a photoelectric conversion unit is configured using two two-dimensional CCD sensors.

FIG. 64 is a plan view of the photoelectric conversion unit shown in FIG. 63;

FIG. 65 shows an AGC (AUTOMATIC GAIN C) when a two-dimensional CCD sensor is used as a photoelectric conversion unit.
FIG. 3 is an explanatory diagram showing a method of (ONCONTROL).

FIG. 66 shows an AGC (AUTOMATIC GAIN C) when a two-dimensional CCD sensor is used as a photoelectric conversion unit.
FIG. 3 is an explanatory diagram showing a method of (ONCONTROL).

FIG. 67 is a time chart showing operation timings of opening switching in the pupil division means and charge accumulation in the photoelectric conversion means.

FIG. 68 is a time chart showing accumulation of electric charge in the photoelectric conversion means, transfer of the accumulated electric charge from the photoelectric conversion means to the arithmetic control means, and arithmetic operation time in the arithmetic control means;

FIG. 69 is a diagram illustrating a relationship between a lens position and a driving time of a photographing optical system.

[Explanation of symbols]

Reference Signs List 1 camera body 2 interchangeable lens structure 3 pupil dividing means 4 photoelectric conversion means 5 arithmetic control means 10 pentaprism 11 shutter 12 film 13 main mirror 14 sub-mirror 15 imaging means 16 storage means 17 reduction optical system 18 display means 19 observation optical system 20 shooting Optical system 21 Information means 22 Condenser lens 23 Re-imaging lens 25 Dach surface 26, 128 Half mirror 27 Photometry means 30 Liquid crystal molecules 31 Glass substrate 32 Transparent electrode 33, 34 Polarizing plate 35 Power supply 36 Switch 37 Dichroic dye molecule 38 Liquid crystal Grains 44, 45, 67, 68, 70, 72, 74, 75, 7
7,79,81,82,84,86,88,90,9
3,94,96,98,100,102,103,10
5, 106, 108, 109 Aperture 51, 151 Photoelectric conversion pixel 52, 53, 56, 152, 153, 156, 158
Gates 54, 55, 154, 155 Charge storage unit 57, 157, 159 Charge transfer unit 60 Image plane 61 Optical axis 62 Imaging stop 63 Lens outer diameter 101, 104, 107 Boundary line 110, 111, 112 Opening 120 Mirror Structure 130 Block 121 Substrate 122 Axis 123 Mirror 126,127 Photoelectric conversion means 129 Pixel column

Claims (2)

[Claims] A photoelectric conversion unit disposed on an imaging surface of a photographing optical system that forms a light flux from a subject, the photoelectric conversion unit converting an image of the subject into an image signal; And at least three openings having different centers of gravity from each other, and at least one opening is selected from the at least three openings, and the first opening and the second opening are arranged in the optical path between them or in the optical path in the photographing optical system. A pupil dividing means for selecting at least one opening having a different center of gravity from the first opening as a second opening, and opening and closing the first and second openings with respect to the light beam in a time-division manner. A focus detection device comprising: a focus detection unit configured to detect a focus state of the imaging optical system based on an image signal of an image of the subject formed on the photoelectric conversion unit by the pupil division unit. . 2. An imaging optical system that forms an image of a light beam from an object, a photoelectric conversion unit that receives an image of the object formed by the imaging optical system, and converts the image into an image signal; At least three openings that are arranged in the optical path between the photoelectric conversion unit or the optical path in the photographing optical system and have different centers of gravity are provided, and at least one opening is selected from the at least three openings. And at least one opening having a different center of gravity from the first opening is selected as a second opening, and the first and second openings are time-divided with respect to the light flux. A pupil dividing unit that opens and closes with a focus; and a focus detecting unit that detects a focus state of the photographing optical system based on an image signal of an image of the subject formed on the photoelectric conversion unit by the pupil dividing unit. And a camera with a focus detection device.