JPH07209576A - Optical detection device and focus control device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a focus control device capable of high-speed focus control operation. [Structure] A focus lens 1 driven by a focus lens driving device 20 is a light beam incident on a camera from an imaging subject.
0, and the diaphragm mechanism 11 driven by the diaphragm drive circuit 21.
Imaging device 13 which is formed by an optical system including
Come in. The output of the image sensor 13 is supplied to the variable gain circuit 22, and the image signal level output from the image sensor 13 is corrected by the change of the diaphragm. Then, the output of the variable gain circuit 22 is supplied to the high frequency component detection circuit 15, and is converted into a focus evaluation value by the high frequency component detection circuit 15.
It is supplied to the processing circuit 16. The processing circuit 16 estimates the in-focus position of the subject based on the in-focus evaluation value obtained when the relative image formation position and the size of the aperture are changed, and the lens is moved in correspondence with the estimated in-focus position. To move.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to detection of the amount of lens blur,
The present invention also relates to an optical detection device that estimates the distance to a subject, and a focus control device that is suitable for use in, for example, a video camera.

[0002]

2. Description of the Related Art Consumer video cameras are equipped with a so-called autofocus function so that the focus on a subject can be automatically adjusted. FIG. 11 shows a configuration example of a focus control device in a conventional video camera. Focus lens 2
Forms an image of a subject (not shown) on the image sensor 3 such as a CCD. The image sensor 3 outputs an image signal (video signal) corresponding to this image to the A / D converter 4.
The A / D converter 4 A / D-converts the input video signal and outputs it to the camera signal processing circuit 5 and the filter 6.

The filter 6 is composed of a high pass filter or a band pass filter, extracts the high frequency component of the input digital video signal, and outputs it to the detection circuit 7. The detection circuit 7 detects the input video signal in field units, generates a focus evaluation value, and supplies the focus evaluation value to the microcomputer 8.

The microcomputer 8 executes a so-called hill-climbing autofocus system process to generate a focus error signal. Then, in response to this focus error signal, the stepping motor 1 is driven to move the focus lens 2 to a predetermined position relative to the image sensor 3. As a result, focus control is performed so that the image of the subject is correctly formed on the image sensor 3.

FIG. 12 is a flow chart showing the arithmetic processing in the microcomputer 8 which executes the above-mentioned hill-climbing autofocus system. First, in step S51, it is determined whether or not it is necessary to start the autofocus operation, and if it is necessary, the process proceeds to step S52 and the microcomputer 8
Drives the stepping motor 1 and the focus lens 2
Is moved in either the direction of moving away from the image pickup device 3 or the direction of approaching it.

Next, in step S53, the focus evaluation value supplied from the detection circuit 7 after the focus lens 2 has been moved is obtained, and it is determined whether or not the component has increased compared to before the focus lens 2 was moved. judge. That is,
As shown in FIG. 13, the focus evaluation value output from the detection circuit 7 is separated from the focus lens 2 in the direction of approaching the image sensor 3 or vice versa with respect to the focus position. However, the value becomes small.
In other words, the focus state can be realized by moving the focus lens 2 in the direction in which the focus evaluation value increases.

Therefore, when the focus evaluation value after the focus lens 2 is moved is larger than that before the focus lens 2 is moved, the steps S53 to S55 are performed.
Then, the focus lens 2 is further moved in the same direction.

On the other hand, when the focus evaluation value after the movement is smaller than that before the movement of the focus lens 2, the process proceeds to step S54 and the moving direction of the focus lens 2 is reversed. . Then, the process proceeds to step S55, and the focus lens 2 is turned in the reverse direction.
To move.

That is, the focus lens 2 is now moved toward the in-focus position. Therefore, in step S56, the value of the focus evaluation value output from the detection circuit 7 is again compared with the value before the movement of the focus lens 2, and if the value is large, the focus lens 2 is moved as it is. Then, when the focus evaluation value does not increase (when the focus position is slightly overshooted), the process proceeds to step S57, the focus lens 2 is slightly returned to the focus position, and then stopped.

As described above, the hill-climbing focus system is composed of three phases, phase 1 to phase 3. That is, in the phase 1 including steps S51 to S54, the focus lens 2 is not moved for the time being, but slightly moved in a direction away from or closer to the image sensor 3. Then, the direction of the in-focus position is determined by determining whether or not the focus evaluation value has increased due to this movement. When the direction of the in-focus position is the opposite direction, the moving direction of the focus lens 2 is reversed. Next, in Phase 2 including steps S55 and S56, the peak value (focus position) of the focus evaluation value is detected. And in Phase 3,
When the peak focus evaluation value is detected in Phase 2,
Therefore, the focus lens 2 is stopped.

As described above, the hill climbing focus system is
A highly accurate autofocus operation can be realized relatively easily without the need for a distance measuring device.

[0012]

By the way, in the above-mentioned hill-climbing focus method, since only the size of the focus evaluation value is determined, the direction of the in-focus position can be obtained.
It is impossible to estimate where the focus position itself is (lens position on the focus position). Therefore, it is relatively difficult to move the focus lens 2 quickly to the in-focus position.

Further, the hill-climbing focus system has a problem that the auto-focus control operation becomes unstable when a plurality of subjects exist at different distances. In particular, when a subject having a higher contrast than the subject in the center of the screen exists in the background, the subject in the background is focused.

In this case, for example, as shown in FIG. 14, it is possible to provide a plurality of focus detection areas A and B, and select an appropriate focus evaluation value from the focus evaluation values of each area to perform focus control. . However, in the hill-climbing focus method, the focus positions of the plurality of areas A and B cannot be detected simultaneously, so the focus lens 2
It becomes difficult to quickly determine the direction to move.

The present invention has been made in view of the above situation, and it is possible to perform focus control at high speed and more accurately. The present invention also provides an optical detection device capable of detecting the amount of lens blur and estimating the distance to the subject.

[0016]

According to the optical detecting device of the present invention, a plurality of image pickups are formed so that the image forming positions of the subject through the optical means by the focus lens are imaged at relatively different positions. The image pickup means is composed of an element, or the image pickup means is composed of an image pickup element whose image formation state is changed in a time-sharing manner by periodically changing the image formation position of the subject through the optical means by the focus lens. A diaphragm control means for controlling the size of the diaphragm in the lens and a high frequency component extraction means for extracting high frequency components of the image signal obtained by the imaging means are basically provided. Then, when the aperture size is changed by a predetermined amount by the aperture control means,
A blur characteristic estimating means for estimating the blur characteristic of an image from the high frequency component of the image signal obtained by the high frequency component extracting means.

Further, the optical detecting device of the present invention further includes a focal length acquiring means for acquiring data on the focal length of the focus lens, and when the size of the diaphragm is changed by a predetermined amount by the diaphragm control means, a high frequency range is obtained. It is characterized by comprising distance estimation means for estimating the distance between the focus lens and the subject based on the high frequency component of the image signal obtained by the component extraction means and the data relating to the focal length obtained by the focal length acquisition means.

Further, the focus control device of the present invention comprises an image pickup means comprising an image pickup element whose image formation state is changed in a time division manner by periodically changing the image formation position of the subject through the focus lens, and the focus lens. Aperture control means for controlling the size of the aperture in, the high frequency component extraction means for extracting the high frequency component of the image signal obtained by the imaging means, and when the aperture size is changed by a predetermined amount by the aperture control means, From the high-frequency components of the image signal obtained by the high-frequency component extraction means, the blur characteristic estimating means for estimating the blur characteristic of the image, and the focus position of the subject with respect to the image sensor based on the blur characteristic obtained by the blur characteristic estimating means In-focus position estimating means for estimating, and moving means for changing the relative position between the optical means and the image sensor based on the estimated value obtained by the in-focus position estimating means. Characterized in that it comprises.

[0019]

In the optical detecting device having the above-mentioned structure, a plurality of image pickup elements arranged at positions where the image forming position of the subject is relatively different, or an image pickup in which the image forming position of the subject is controlled to be different in time division The element provides an image signal.
This image signal is supplied to the high frequency component extraction means, and the high frequency component in the image signal in the attention area of the image is extracted.
Then, the blur characteristic estimating unit estimates the blur characteristic of the attention area of the image by the change of the high frequency component of the image signal when the size of the aperture of the focus lens is changed by a predetermined amount.
Therefore, the blur amount detecting device can be realized by the blur characteristic estimating means.

The high frequency component of the image signal when the aperture of the focus lens is changed by a predetermined amount by the distance estimating means,
The distance between the focus lens and the subject is estimated based on the data regarding the focal length of the focus lens. Therefore, the distance estimation means can detect the distance to the subject, and the distance detection device can be realized.

In the focus control device having the above structure, the focus position estimating means estimates the focus position of the object with respect to the image pickup element based on the blur characteristic, and the moving means uses the estimated value to estimate the focus lens and the image pickup element. The relative position with is changed. Therefore, it becomes possible to quickly move the lens to the in-focus position corresponding to the in-focus position of the subject with respect to the image pickup device obtained by the in-focus position estimating means, and the high-speed focus control operation becomes possible.

[0022]

1 is a block diagram showing the configuration of the first embodiment (optical detection device) of the present invention.
In FIG. 1, a focus lens 10 as an optical means.
Is configured to project an image of a subject (not shown) onto the optical element 12 including the half mirror 12a via the diaphragm mechanism 11. The images of the subject divided by the half mirror 12a are image pickup devices 13a and 13b formed of two CCDs which are image pickup means arranged at relatively different positions.
Is projected on each.

The first image pickup device 13a (hereinafter CCD 1)
Is arranged immediately after the optical element 12 located on the transmission optical axis of the half mirror 12a, and the second image pickup element 13b (hereinafter referred to as CCD 2) is arranged on the optical axis of the focus lens 10. Is arranged on the side surface of the optical element 12 located on the reflection optical axis of the half mirror 12a bent by 90 degrees via a transmission plate 14. The transmission plate 14
Has a thickness of 2 dd, as will be described later, and by interposing a transmission plate 14 having a thickness of 2 dd, the imaging positions of the subject on the CCD 1 and CCD 2 are relatively different. Is made to be.

The CCD 1 uses a high-frequency component extraction circuit (high-pass filter circuit) 15 as high-frequency component extraction means for the image signal (video signal) corresponding to the formed image of the subject.
supply to a. Further, the CCD 2 supplies an image signal (video signal) corresponding to the formed image of the subject to a high frequency component extraction circuit 15b as high frequency component extraction means. Although not shown in detail in the drawing, these high-frequency component extraction circuits 15a and 15b extract a high-frequency component from a preamplifier that amplifies an image signal supplied from each CCD 1 and CCD 2 and an output of this preamplifier. It is composed of a filter circuit for extraction and a detection circuit for detecting the absolute value of the output of this filter circuit.

These high frequency component extraction circuits 15a and 15
Focus evaluation values h and h'are output from b, respectively, and these focus evaluation values h and h'are supplied to a processing circuit (blur characteristic estimation means, distance estimation means) 16 including a microcomputer.

The processing circuit 16 includes the diaphragm mechanism 11
An aperture drive circuit 17 as an aperture control means for controlling the aperture degree is connected, and the processing circuit 16 supplies an aperture control signal to the drive circuit 17. Then, the processing circuit 16 can estimate the blur characteristic based on the focus evaluation values h and h ′ and the aperture control signal. Further, the distance to the subject can be calculated (estimated) based on the blur characteristic and the focal length f of the focus lens 10 as the optical means, and a passive distance measuring device can be realized.

Next, the operation of the above apparatus will be described, but before that, the optical detection principle of the detection apparatus of the present invention will be described.

The blur of the picked-up image at the time of non-focus is due to the circle of confusion, and the blur characteristic is given by the two-dimensional Fourier transform of the circle of confusion. Therefore, if the sizes of the circles of confusion are the same even if the positions of the image pickup surfaces are different, the blur characteristics are the same, and the amounts of high-frequency components obtained from the image pickup elements when the same subject is imaged are also the same.

In this embodiment, the two image pickup planes are arranged on different image pickup planes.
Focusing on the high-frequency components included in the outputs of the two image pickup devices (CCD1 and CCD2), the combination of diaphragm diameters p (0) and pp with the same amount of high-frequency components (that is, the sizes of circles of confusion are equal) The focus position is estimated and the distance to the subject is calculated.

Where A is the distance from the image-side principal point of the optical system to the in-focus position, D is the distance from the center point of the positions of the two image sensors to the in-focus position, and dd is the position of the two image sensors. Distance from center point to image sensor r: Diameter of circle of confusion p (0): Diameter of exit pupil where diameter of circle of confusion on CCD1 image plane is r pp: Diameter of circle of confusion on CCD2 plane is r If the diameter of the exit pupil is (p (0)> pp), r: (D + dd) = pp: A r: (D-dd) = p (0): A due to the similarity relationship. If r and A are deleted from the above equation, the following equation is obtained. D = dd {(p (0) + pp) / (p (0) -pp)} (1)

The relationship between the in-focus position and the image pickup surface is roughly classified into FIG.
Although two types shown in (A) and (B) are conceivable, the formula (1) is common to both types, and only the sign of D when calculating A from z0 described later is different. The in-focus position can be obtained using this equation (1).

The processing operation of the processing circuit 16 will be described below with reference to the flow charts of FIGS. 3 and 4. First, in step S1, the high frequency component extraction circuit 15a
And focus evaluation values h (0) and h '(0) output from 15b
Is taken in, and the gain is corrected according to the size of the aperture in step S2. That is, the corrected focus evaluation values (hereinafter referred to as standardized evaluation values) e (0) and e '(0) when the diameter of the diaphragm is p (0) (in the initial state) are calculated from the following equations. To do. e (0) = h (0) / p (0) ² e ′ (0) = h (0) / p (0) ² (2)

Next, the size (diameter) of the aperture is reduced for each field (or frame). FIG. 5 shows the relationship between the field number (diaphragm size) and the standardized evaluation value at this time. In the figure, “#” is a standardized evaluation value obtained from the output of the CCD 1, and “◯” is a standardized evaluation value obtained from the output of the CCD 2. The horizontal axis of FIG. 5 shows the diameter of the diaphragm, and the diameter of the diaphragm decreases toward the right side.

Next, the process proceeds to step S3 and step S2.
The magnitudes of the initial standardized evaluation values e (0) and e '(0) obtained in step 2 are compared. Then, the smaller standardized evaluation value e ′ (i) or e (i) increases as the size of the aperture decreases,
The aperture amount when the value is equal to the larger initial standardized evaluation value e (0) or e '(0) is obtained.

Therefore, as shown in FIG. 5A, the initial standardized evaluation value e (0) of the CCD 1 when the initial aperture diameter is p (0) is the initial standardized evaluation value of the CCD 2. e '
If it is larger than (0), the process proceeds to step S4 and thereafter,
As shown in FIG. 5B, when the initial standardized evaluation value e ′ (0) of the CCD 2 is larger, the process proceeds to step S11 and subsequent steps.

In step S4, the variable i is set to 1, and the process proceeds to step S5. In step S5,
The focus evaluation value h '(i) (h' (1) in this case) is fetched from the high-frequency component extraction circuit 15b, and in step S6, the standard corresponding to the fetched focus evaluation value h '(1). The converted evaluation value e ′ (1) is calculated according to the equation (2) as in the case described above.

Then, in step S7, it is determined whether or not the current standardized evaluation value e '(1) obtained in step S6 is smaller than the initial standardized evaluation value e (0) of the CCD 1,
If it is smaller, the process proceeds to step S8 and the variable i is set to 1
Only increments to i = 2.

Then, returning to step S5, the next focus evaluation value h '(2) is fetched from the high frequency component extracting circuit 15b. Then, in step S6, the standardized evaluation value e '(2) corresponding to the focus evaluation value h' (2) just fetched is calculated according to equation (2), and in step S7 the standardized evaluation value just calculated is calculated. It is determined whether e ′ (2) is smaller than the initial standardized evaluation value e (0) of the CCD 1. The standardized evaluation value e '(2) is C
If it is smaller than the initial standardized evaluation value e (0) of CD1, the process proceeds to step S8, the variable i is incremented by 1, and i = 3. Then, the process returns to step S5 and the same process is repeated thereafter.

As described above, the variable i (field)
Until the standardized evaluation value e ′ (i) of the CCD 2 is equal to or larger than the initial standardized evaluation value e (0) of the CCD 1 in step S7. , And similar processing is repeated.

Normally, it is unlikely that the standardized evaluation value e '(i) will be exactly the same as the initial standardized evaluation value e (0). Therefore, in step S7, when it is determined that e ′ (i) is equal to or larger than e (0), the process proceeds to step S9, where e ′ (i) is larger than e (0). The amount of aperture at i is p (i), and the field immediately before that is
With the diaphragm amount of (i-1) set to p1, the standardized evaluation value e ′ of the CCD 2 is the initial standardized evaluation value e of the CCD 1 according to the following equation.
The aperture amount pp when it becomes equal to (0) is calculated by linear interpolation.

Pp = {(e ′ (i) −e (0)) × p (i−1) + (e (0) −e ′ (i−1)) × p (i)} / {e ′ (i) -e '(i-1)} (3)

Next, the standardized evaluation value e'of the CCD 2 is C
From the aperture amount pp which becomes equal to the initial standardized evaluation value e (0) of CD1, the center position of the image pickup surfaces of CCD1 and CCD2 and the focus position of the optical system (focus position for the current subject, the same applies below) The shift amount D is calculated by the following formula. D = -dd * (p (0) + pp) / (p (0) -pp) (4)

Further, the image side principal point of the optical system, CCD 1 and CC
If the distance from the center position of the image pickup surface of D2 is z0, the focal position for the image pickup subject within the measurement distance frame is A = z0−
Therefore, the distance L to the subject is calculated by the following known equation.
Can be asked. {L-f} × {( z0-D) -f} = - f 2 ...... (5)

On the other hand, in step S3, as shown in FIG.
As shown in, when it is determined that the initial standardized evaluation value e '(0) of the CCD 2 is larger than the initial standardized evaluation value e (0) of the CCD 1, the process proceeds to step S11, and thereafter. The process is executed. The processing of steps S11 to S16 is basically the same as the processing of steps S4 to S10 described above, and includes h (0), h (i), e (0),
The relationship between e (i) and h '(0), h' (i), e '(0), e' (i) is
The only difference is that they are mutually replaced and dd is replaced by -dd.

As described above, the high frequency component extraction circuit 15a
The blur characteristic can be estimated based on the focus evaluation values h and h ′ and the aperture control signal output from the and 15b. Therefore, by detecting this blur characteristic, it can be used in a lens blur amount detection device for lens blur correction during camera shooting. Furthermore, the distance to the subject can be calculated (estimated) based on the blur characteristic and the focal length f of the focus lens 10 as the optical means.
This makes it possible to realize a passive distance measuring device.

FIG. 6 is a block diagram showing the configuration of the second embodiment (focus control device) of the present invention. Note that, in FIG. 6, the same reference numerals as those in FIG. 1 denote corresponding portions.

A camera incident light beam from an imaged subject is imaged by an optical system including a focus lens 10 driven by a lens drive circuit 20 and an aperture mechanism 11 driven by an aperture drive circuit 21, and is an image pickup device composed of a CCD. It is incident on 13. The output of the image sensor 13 is supplied to the variable gain circuit 22 via a preprocessing circuit such as a preamplifier (not shown).
The variable gain circuit 22 corrects the image signal level in accordance with the change in the amount of light incident on the image sensor 13 due to the change in the aperture shape of the optical system.

The gain of the variable gain circuit 22 is controlled by the processing circuit 16. The output of the variable gain circuit 22 is supplied to the normal camera signal processing circuit 23 and also to the high frequency component extraction circuit 15, and the high frequency component extraction circuit 1
It is converted into a focus evaluation value by 5 and supplied to the processing circuit 16. The processing circuit 16 estimates a blurring function for each subject based on the focus evaluation value obtained when the relative image formation position and the size of the diaphragm are changed, and estimates the focus position based on the blurring function for each subject. The estimating means estimates the in-focus position of the subject with respect to the image sensor. Then, the relative position between the optical means and the image pickup device is changed by the moving means based on the estimated value obtained by the focus position estimating means, whereby the autofocus operation is achieved.

The operation of the embodiment shown in FIG. 6 will be described with reference to FIG. The position of the focus lens 10 driven by the lens drive circuit 20 is perturbed for each field with a width of 2 dd, as shown in FIG. That is, the position D is moved periodically by ± d in the optical axis direction. As a result, the image formation state on the image pickup device 13 changes in a time division manner. Further, the diaphragm mechanism 11 driven by the diaphragm driving circuit 21 sequentially reduces the diaphragm diameter to a constant value every two fields, as shown in FIG. Image sensor 1 by reducing the aperture
The gain of the variable gain circuit 22 that corrects (cancels) the level decrease of the image signal due to the decrease of the incident light amount of 3 is inversely proportional to the square of the diaphragm diameter, and as shown in FIG. Increase to.

The focus evaluation value obtained from the high frequency component detecting circuit 15 is shown in FIG. In the figure, “x” and “◯” are focus evaluation values corresponding to subjects at different distances in the imaging screen.

By the same method as in the first embodiment, the size of the diaphragm with which the blur amounts are equal is obtained. In the following description, the distance measuring area corresponding to "x" in FIG.
If the focus evaluation value e (0) of the odd field is larger when the initial aperture diameter is p (0), the focus diameter e of the even field becomes equal to e (0) due to the reduction of the aperture diameter.
Calculate p. That is, if the focus evaluation values of the even fields when the aperture diameters are p (1) and p (2) are e '(1) and e' (2),
By linear interpolation, pp = {(e ′ (2) −e (0)) × p (1) + (e (0) −e ′ (1)) × p (2)} / ( e '(2) -e' (1)) ... (6)

Next, the focus evaluation value of the even field is e (0)
From the diaphragm diameter pp that is equal to, the shift amount D between the center position of the perturbed image pickup surface and the in-focus position of the optical system is obtained by the following calculation formula shown as the above formula. D = dd × (p (0) + pp) / (p (0) -pp) (7)

Further, if the distance between the image-side principal point of the optical system and the center position of the perturbed image pickup surface is z0, the focal position for the image pickup subject in the distance measuring frame is A = z0-D. In the above description, the focus evaluation value e (0) of the odd field is larger when the initial aperture diameter is p (0), but the focus evaluation value of the even field is larger when the initial aperture diameter is p (0). Evaluation value is e '(0)
In the case where is larger (in the case of “◯” in FIG. 6D), the relationship of e (0), e ′ (1), and e ′ (2) described above is replaced by the output of the image sensor in the even and odd fields. It can be calculated in the same manner.

Next, a method for performing the divided distance measurement, which is a feature of this embodiment, will be described. In short, this division distance measurement determines the imaging position where the captured image becomes a preferable in-focus state from the position Z0 (H, V) of the focus lens 10 corresponding to each area in the imaging surface calculated in the above processing. By moving the focus lens 10 to the image forming position, a good autofocus operation is performed.

As shown in FIG. 8, each area in the image pickup plane is divided into, for example, 12 in the horizontal (H) direction and 9 in the vertical (V) direction, and defined as areas W1-1 to W9-12, respectively. To be done. Then, each area W _VH (if necessary, W _VH
The focus position of the focus lens 10 (abbreviated as _VH ) is Z0 (H, V).

The operation of the divided distance measurement will be described below with reference to the flowchart shown in FIG. First, in step S31, the position Z0 (H, V) when the focus lens 10 is at the in-focus position is processed by the median filter to obtain data Z1 (H, V). That is, the average value of the middle data among the data of the neighboring areas including the data of interest is output. As a result, data in a small area (which is likely to be not the main subject) is removed and Z0 (H, V)
If an error occurs, the error data can be removed.

Next, the process proceeds to step S32, where the foremost subject near the center of the screen is the main subject in many cases, so the horizontal block number Hc of the predetermined central region WHcVc is the region representing the maximum value. Is temporarily set as the horizontal block number Hm. Similarly, the vertical block number Vc of the area is provisionally set as the vertical block number Vm of the area representing the maximum value.

Next, the process proceeds to step S33, and step S3
The deviation (im, jm) from the area WHmVm of the area in the vicinity of the area WHmVm set in 2 and in which the maximum value can be obtained in the data Z1 (H, V) is detected.

The detailed processing of step S33 in FIG. 9 is shown in FIG. As shown in FIG. 10, first, in step S41, an initial value 0 is set in the register max in which the maximum data of the data Z1 (H, V) is set, and -1 is initialized in the variable i. It
Next, in step S42, -1 is initialized to the variable j. Then, in step S43, step S42
To the block numbers Hm and Vm set in step S41, step S41
And the median-filtered data Z1 (Hm + i, Vm +) in the area Whm + iVm + j of the block number (Hm + i, Vm + j) obtained by adding the variables i and j set in S42 and S42.
It is determined whether j) is larger than max.

If this determination is YES, step S4
4, the variables im and jm are set to the variables i and j set in step S41 or S42, respectively. And Z1 (Hm + i, Vm +
The value of j) is set. That is, the maximum value of Z1 (H, V) is set in the register max, and the variables i and j are set in the deviations im, jm of the block numbers that specify the area.

Then, the process proceeds to step S45, the variable j is incremented, and if it is determined in step S46 that the variable j is not 2 or more, the process returns to step S43 and the subsequent processes are repeatedly executed.

When it is determined in step S46 that the variable j has a value larger than 1, that is, 2 or more, the process proceeds to step S47, and the variable i is incremented this time. Then, in step S48, the variable i
When it is determined that is less than 1 or equal to 1, the process returns to step S42, and the subsequent processes are repeatedly executed. Then, in step S48, the variable i
When it is determined that is greater than 1, that is, 2 or more, the process is terminated and returns to step S33 of FIG.

That is, the largest data Z1 (H, V) is selected from the total of nine areas WHV shifted by one in the vertical and horizontal directions centering on the central area WHcVc set in step S32 by the processing of FIG. The output area is selected.

Then, the process proceeds to step S34 in FIG.
It is determined whether or not the variables im and jm set in step S33 (S44) are both 0. If neither is 0, the process proceeds to step S35, and the values obtained by adding the variables im and jm to the variables Hm and Vm are updated as new Hm or Vm.

Next, in step S36, Hm or V
It is determined whether m is 1, Hm is equal to twice Hc, or Vm is equal to twice Vc. When it is determined that any one of the conditions is satisfied, the process proceeds from step S36 to step S37,
The process ends. That is, at this time, the focus lens 1
The position of 0 is stored in the register max (its value is set in step S44), and the block number of the area corresponding to the position of the main subject is (H
m, Vm).

As described above, for example, at the end of the screen,
Even if there is an object closest to the video camera, the distance measurement processing can be performed on the object in the central portion, that is, the object in the attention area of the image, without being affected by this.

As described above, in the present embodiment, the image pickup screen is divided into a plurality of parts, and the preferred focus lens position is selected from the focus lens position information obtained from each part, thereby performing the autofocus operation in consideration of the composition. You can

In the above second embodiment, as shown in FIG.
As described in (A), the image pickup unit is employed so that the image formation state is changed in a time division manner by periodically changing the image formation position of the subject with respect to the image pickup element. Such an image pickup means can also be adopted for the first embodiment shown in FIG. 1, and the same effect can be achieved.

[0069]

As described above, according to the optical detecting device of the present invention, the blur characteristic is estimated based on the focus evaluation value obtained by the high frequency component detecting circuit and the aperture size. To be done. Therefore, a blur amount detection device can be realized and can be applied to image blur restoration. Further, the distance to the subject can be calculated based on this blur characteristic and the focal length of the optical system, and thus a passive distance measuring device can be provided.

Further, according to the focus control apparatus of the present invention, the focus position of the object with respect to the image pickup device is estimated based on the blur characteristic, and the relative position between the focus lens and the image pickup device is calculated by the moving means based on this estimated value. Be changed. Therefore, it becomes possible to quickly move the lens to the in-focus position corresponding to the in-focus position of the subject with respect to the image pickup device obtained by the in-focus position estimating means, and the high-speed focus control operation becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an optical detection device of the present invention.

FIG. 2 is a diagram for explaining the optical operation principle of FIG.

FIG. 3 is a flowchart illustrating the operation of the embodiment of FIG.

FIG. 4 is a flowchart following FIG.

5 is a characteristic diagram for obtaining a standardized evaluation value in the embodiment of FIG.

FIG. 6 is a block diagram showing a configuration of an embodiment of a focus control device of the present invention.

FIG. 7 is a diagram for explaining the operation in the embodiment of FIG.

FIG. 8 is a diagram illustrating how a screen is divided into a plurality of areas.

9 is a flowchart showing a calculation process in the embodiment of FIG.

10 is a flowchart showing detailed processing of some steps in the flowchart of FIG.

FIG. 11 is a block diagram showing a configuration example of a conventional focus control device.

FIG. 12 is a flowchart illustrating the operation of the example shown in FIG.

FIG. 13 is a diagram showing characteristics of a focus evaluation value.

FIG. 14 is a diagram illustrating how a screen is divided into a plurality of areas.

[Explanation of symbols]

 10 Focus Lens 11 Aperture Mechanism 12 Optical Element 12a Half Mirror 13, 13a, 13b Imaging Device (CCD) 14 Transmission Plate 15, 15a, 15b High Frequency Component Extraction Circuit 16 Processing Circuit 17 Aperture Drive Circuit 20 Lens Drive Circuit 21 Aperture Drive Circuit 22 variable gain circuit 23 camera signal processing circuit

Claims (7)

[Claims] 1. An image pickup unit configured to form an image on an object at a relatively different image forming position, an optical unit that forms an image of the light of the object on the image pickup unit, and the optical unit. A diaphragm control means for controlling the size of the diaphragm, a high frequency component extraction means for extracting high frequency components of the image signal obtained by the image capturing means, and when the diaphragm size is changed by a predetermined amount by the diaphragm control means. And a blur characteristic estimating means for estimating blur characteristics of an image from the high frequency components of the image signal obtained by the high frequency component extracting means. 2. An image pickup unit configured to form an image on a subject at a relatively different image forming position, an optical unit for forming an image of the light of the subject on the image pickup unit, and the optical unit. A diaphragm control means for controlling the size of the diaphragm, a high frequency component extraction means for extracting a high frequency component of the image signal obtained by the imaging means, and a focal length acquisition means for acquiring data relating to the focal length in the optical means. When the aperture size is changed by a predetermined amount by the aperture control means, the high frequency component of the image signal obtained by the high frequency component extraction means and the data about the focal length obtained by the focal length acquisition means An optical detection device comprising: an optical means and a distance estimation means for estimating a distance between a subject and the subject. 3. An image pickup unit configured to form an image on a subject at a relatively different image forming position, an optical unit for forming an image of the light of the subject on the image pickup unit, and the optical unit. A diaphragm control means for controlling the size of the diaphragm, a high frequency component extraction means for extracting high frequency components of the image signal obtained by the image capturing means, and when the diaphragm size is changed by a predetermined amount by the diaphragm control means. A high-frequency component of the image signal obtained from the high-frequency component extracting means, a blur characteristic estimating means for estimating blur characteristics of an image, and a subject of the image sensor based on the blur characteristic obtained by the blur characteristic estimating means. A focusing position estimating means for estimating a focusing position, and a moving means for changing a relative position between the optical means and the image sensor based on an estimated value obtained by the focusing position estimating means. A focus control device which is characterized by being capable of 4. The optical detection device according to claim 1 or 2, or the focus control device according to claim 3, wherein the image pickup means includes a plurality of image pickup elements arranged at different positions. 5. The optical detection device according to claim 1 or 2, wherein the image pickup unit includes one image pickup element, and the image pickup element is periodically moved to different positions. Item 4. The focus control device according to item 3. 6. The image pickup unit according to claim 4, further comprising a half mirror that divides the image of the subject and forms an image on a plurality of image pickup elements arranged at relatively different positions. Optical detection device or focus control device. 7. The high-frequency component extraction means is configured to extract high-frequency components of an image signal in a region of interest of an image obtained by the image pickup means. An optical detection device or a focus control device as described in 1.