JPH089232A - Imaging device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] In an image pickup apparatus in which the focus detection range can be changed, it is intended to prevent a malfunction of AF caused by movement of a subject or a small focus detection range. An electronic viewfinder 24 for displaying a video signal on a screen, a gate circuit 27 for taking in a video signal corresponding to a focus detection range in the screen, a line-of-sight detection circuit 6 for changing the range according to the line of sight, Focus detection means for performing focus detection by extracting a signal that changes according to the focus state from the image signals within the range, focus adjustment means for performing focus adjustment based on the output of the focus detection means, and screen for the range While displaying the position within the screen 24,
An image pickup apparatus comprising a microcomputer 29 for controlling the operation of the focus adjusting means on the basis of a video signal corresponding to the outside of the range displayed by the range displaying means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus for performing focus adjustment on an image within a range designated on a screen.

[0002]

2. Description of the Related Art In the field of consumer imaging devices such as video integrated cameras, various measures have been taken in order to obtain higher quality images more easily. In recent years, the standard equipped auto focus (AF) is to eliminate the hassle of adjusting the focus each time a picture is taken, and is a simple function that serves the purpose of easily obtaining a good image. It can be said that this is an example.

By the way, the AF is a mechanism for an imaging device such as a camera to "discriminately" determine the photographing situation and adjust the lens position to a state suitable for the situation. It also occurs when it is not reflected in the image.

For example, when a distant subject and a near subject coexist in the image pickup screen, the information of the entire image pickup screen is A.
When the F operation is executed, any one of the plurality of subjects will be in focus, but it is impossible for the imaging device to judge whether or not it is the main subject to be focused.

In order to avoid such a situation as much as possible,
Focusing on the subject in the center of the shooting screen,
It is general to take a method of executing AF based on the result. This is based on the fact that the photographer often places the main subject in the center of the screen when photographing. This method has a drawback that the focus may not be adjusted appropriately with respect to the main subject when the main subject is placed in a place other than the center of the screen.

On the other hand, the applicant of the present invention has proposed in Japanese Patent Application No. 4-154165 that a photographer looking at the viewfinder can obtain the optimum focus and exposure regardless of where the main subject is in the image pickup screen. Has proposed an imaging device that can select the main subject with the line of sight. According to this photographing device, the position of the main subject can be freely changed while limiting the distance measuring area.

In this case, the photographing device detects the line-of-sight position of the photographer, and immediately moves the distance measurement area (focus detection area) in correspondence with the detected position to obtain the optimum focus and exposure in the area.

Conventionally, as an automatic focusing device used in a video camera such as a video camera, a high frequency component of a video signal obtained from an image pickup device such as a CCD is extracted and a lens is used so that the high frequency component becomes maximum. A so-called hill-climbing method is known in which the position is driven to adjust the focus.

The applicant of the present invention, in Japanese Patent Application No. 6-89947, knows the focus degree of the image pickup screen from the video signal and corrects the automatic focus adjustment operation so that the lens does not move carelessly near the focus point. We are proposing an autofocus system that does. According to this, the maximum value of the focus signal in the video signal is normalized by the maximum value of the brightness difference component, and the degree of focus of the video is known to restrict the high-speed hill climbing operation near the focus.

Using the flow chart shown in FIG.
The operation algorithm will be described.

First, in step 601, the focus lens is slightly oscillated back and forth (this operation is temporarily called a wobbling operation), and it is determined whether the focus is in focus or out of focus according to the change of the focus signal at that time. .

Focus is achieved at step 602 (Yes).
If it is determined that the focus lens has stopped, the focus lens is stopped in step 603, and the process goes to the restart determination routine in step 604 to monitor whether or not the restart has been performed. This restart is performed when the in-focus state is reached and the focus lens is stopped, and then when it is determined that the lens is out of focus, the focus AF is performed again.
This is a process for activating an operation.

If it is determined in step 602 that the image is out of focus (No), step 605 takes in the normalization value, and step 606 determines whether the normalization value can be determined to be in focus.

When it is determined in step 606 that the object is in focus (Yes), the high speed mountain climbing operation is not performed, and the process proceeds to step 601 where the wobbling is performed again to perform the in-focus determination. In this way, the operation increases the stability during focusing.

If it is determined in step 606 that the subject is not in focus (No), that is, if neither the wobbling determination result in step 602 nor the determination result based on the normalized value in step 606 is determined to be in focus, The process proceeds to step 607, and high speed hill climbing is performed in the direction of the determination result by the wobbling operation.

Then, in step 608, it is determined whether or not the focal point, that is, the apex of the AF evaluation value is exceeded, and if not, the process returns to step 607 to continue high speed mountain climbing,
If it has exceeded, at step 609 it is returned to that vertex.

However, the object may change due to panning or movement of the object itself during the operation of returning to the apex. Therefore, if the focus lens reaches the apex at step 610, the next place is really now. The wobbling operation is performed by returning to step 601 to determine whether it is the vertex, that is, the in-focus point.

If the wobbling operation determines that the object is in focus, restart monitoring is performed, and if it is determined that the object is not in focus, the high speed hill climbing operation is performed in the direction of the determination result. By repeating such an operation, the AF operation is performed so as to constantly maintain the focus.

Now, the wobbling operation will be described with reference to FIG. In the wobbling operation, the focus lens is slightly vibrated back and forth in the optical axis direction as described above.
Although the change of the F evaluation value is observed, the operation is affected by the flicker such as a fluorescent lamp.

FIG. 8 shows two types of driving with and without flicker such as a fluorescent lamp. Here, what is common to both operations is that the focus lens is driven in a certain direction. When the signal increases, the driving direction is not changed, and when the signal decreases, the driving direction is reversed. Details are described in Japanese Patent Application No. 6-89947.

That is, the focus lens is always driven in the direction in which the focus signal increases. By being controlled in this way, the focus is constantly driven in the direction of the in-focus point during the wobbling operation. Therefore, even if the wobbling operation is repeated, the in-focus point can be finally reached even though the speed is slow.

[0022]

In the image pickup apparatus capable of changing the focus detection range on the screen as described above,
The capture area of the AF information was only the same area as the display showing the capture area in the imaging screen. If the display indicating the capture area is too large for the screen, the degree of freedom in subject selection is lost and the photographer loses the ability to select the subject by moving the capture area. Therefore, it is desirable to make it as small as possible.

However, if it is too small, the display of the capture area may not be stable on the subject that the photographer wants to photograph. Therefore, a capture area having a size that takes them into consideration is set.

However, according to the above example, there are the following drawbacks.

In FIG. 5A, 501 and 502 are the same subject, and it is assumed that they are moved from 501 to 502 as shown by the arrow. Reference numeral 503 is an AF evaluation value acquisition region, that is, a focus detection range, and is also a display region that is simultaneously superimposed on the imaging screen.

When the object is in 501, the object is in the focus detection range 503, but when it is moved to 502, it goes out of the focus detection range. Therefore, the AF evaluation value fluctuates, and the AF mistakenly recognizes that the focus is out of focus, and starts to climb the mountain at high speed. Therefore, the subject 502 is blurred by the movement of the focus lens.

The present invention has been made in order to solve the above-mentioned drawbacks, and an object of the present invention is to move the focus detection range particularly in an image pickup apparatus in which the focus detection range for taking in the AF evaluation value can be changed. Or to prevent a malfunction of AF caused by a small focus detection range.

[0028]

In order to solve the above problems, according to the invention of claim 1 of the present application, display means for displaying a video signal on the screen (LCD display circuit 23 in the embodiment). , Corresponding to electronic viewfinder 24)
And a video signal fetching means for fetching a video signal corresponding to a predetermined range (corresponding to a focus detection area in the embodiment) on the screen (gate circuits 261, 263 of the AF evaluation value processing circuit 26 in the embodiment). Equivalent to 265),
Range setting means for changing the range (corresponding to the frame generation circuit 27 in the embodiment) and instruction means for controlling the range setting means to change the set position of the range within the screen (visual axis detection in the embodiment). (Corresponding to the circuit 6) and a focus detecting means (in the embodiment,) for performing focus detection by extracting a signal that changes according to the focus state from the video signals within the range captured by the video signal capturing means. AF evaluation value generation circuits 262, 264 in the AF evaluation value processing circuit 26
266), a focus adjusting means for adjusting the focus based on the output of the focus detecting means (corresponding to the driver 18 and the motor 17 in the embodiment), and the position of the range within the screen. And a range display means (corresponding to the frame generation circuit 27, the LCD display circuit 23, and the electronic viewfinder 24 in the embodiment) to be superimposed and displayed on the video signal displayed by the range display means. A control means (corresponding to the microcomputer 29 in the embodiment) for controlling the operation of the focus adjusting means on the basis of the video signal corresponding to the outside of the range.

As a result, a stable focus detection operation can be performed even when the subject moves out of the focus-detectable range displayed on the screen, or when the subject repeatedly moves in and out near the boundary. .

Further, even if the subject is out of the focus detectable range displayed on the displayed screen, the focus adjustment operation is prevented from being immediately displaced, and the response characteristic given to the photographer with respect to the out-of-focus, Since the response characteristic in the actual focus control operation is different, the operation feeling of the photographer can be stabilized and the burden on the photographer can be reduced.

According to a second aspect of the present invention, the control means controls the range setting means to control the range (implementation) when a focused state cannot be obtained from a video signal within the range. A video signal corresponding to a predetermined external range (corresponding to the focus detection areas 504 and 505 in the embodiment) adjacent to the focus detection area 503) is extracted and converted into a signal corresponding to the external range. Based on this, focus control is performed so that control is performed.

As a result, when the subject goes out of the focus detection area displayed on the screen, it does not immediately go into high-speed hill climbing, especially for movement in the horizontal direction, and a stable focus is obtained. The detection operation becomes possible.

Further, according to the invention of claim 3 of the present application, the control means controls the range (in the embodiment, the focus detection area 503).
(Corresponding to) and external regions (corresponding to the focus detection regions 504 and 505 in the embodiment) are set on the left and right, and a video signal corresponding to the external range is extracted, and a signal corresponding to the external range is extracted. The focus detection is performed based on the above.

As a result, when the subject goes out of the focus detection area displayed on the screen, it does not immediately enter the high-speed hill climbing, especially with respect to the movement in the horizontal direction, and the stable focus is obtained. The detection operation can be performed, the operation feeling of the photographer can be stabilized, and the burden on the photographer can be reduced.

[0035]

Embodiments of the image pickup apparatus according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of the basic configuration of the first embodiment of the present invention. In this embodiment, a case where the present invention is used for a video integrated camera will be described.

In the first embodiment, while the set position of the focus detection area is being moved, the AF operation is prohibited, and focusing on an unintended subject image causes a malfunction in AF. To prevent.

In the figure, EYE is the eyeball of the operator excluding the finder of the video-integrated camera, and 1 is the line-of-sight detection device block. Reference numeral 2 denotes an infrared light emitting diode (IRED) that irradiates the eye with infrared rays in order to detect the position of the line of sight of the operator on the screen of the operator.
The driver 4 for driving the infrared light emitting diode by the support of 4 is a light receiving sensor for receiving the infrared light from the infrared light emitting diode 2 reflected by the eyeball EYE, and for example, a CCD is used. Reference numeral 5 is an amplifier for amplifying the output signal of the light receiving sensor 4, and 6 is an eyeball E of the operator based on the output signal of the amplifier 5.
It is a visual axis detection circuit that analyzes the visual axis position of YE.

In this line-of-sight detection device, the operator's eyeball is irradiated with infrared rays from IRED2, and the reflected light is reflected by the CCD.
3 is received, and the eye-gaze image is analyzed by the line-of-sight detection circuit 6 to detect the gazing point in the finder screen.

Further, in the present embodiment, the visual axis detecting device 6 is unitized and arranged in the finder of the video integrated camera.

Therefore, as a visual finder unit with a line-of-sight detection device, various controls can be performed by gazing at the image displayed on the finder screen, which has high versatility and can be controlled in fields other than video cameras. The present invention can be widely applied as a line-of-sight detection unit including a display screen for displaying an image used for selection and a line-of-sight detection device for detecting a gazing point in the screen.

OB is a subject, 7 is a photographic lens optical system, and 8 is
Is a fixed first lens group, 9 is a variable power lens, 10 is a diaphragm,
Reference numeral 11 is a fixed third lens group, and 12 is a focus compensating lens which has a correction function for performing focus adjustment and also for correcting a focus plane movement at the time of zooming operation. With these, a photographing lens optical system is configured. There is.

Further, 13 is a variable power lens motor for moving the variable power lens 9, 14 is a variable power lens driver for driving the variable power lens motor 9, 15 is an IG meter for driving the diaphragm 10 to control the aperture amount, 16 Is an IG driver for driving the IG meter, 17 is a focus compensating lens motor for moving the focus compensating lens, and 18 is a focus compensating lens driver for driving the focus compensating lens motor.

Reference numeral 19 is an image pickup device such as a CCD, 20 is an amplifier for amplifying the image pickup signal outputted from the image pickup device 19 to a predetermined level, 21 is a luminance signal and a color signal from the output signal of the amplifier 20, and A camera signal processing block for converting a television signal standardized by performing signal processing such as ranking processing, addition of a synchronization signal, and gamma correction, 22 is an amplifier, 23 is a television signal output from the amplifier 22 is a liquid crystal monitor LCD display circuit for driving and displaying an electronic viewfinder composed of
24 is an electronic viewfinder with a liquid crystal monitor. The electronic viewfinder 24 may be, for example, a CRT.

The television signal output from the camera signal processing block 21 is supplied to a video tape recorder (not shown) and recorded on a magnetic tape or the like. The LCD display circuit 2 displays the image information reproduced by the VTR.
3 to supply electronic viewfinder 24
Can be played at.

Reference numeral 25 denotes a frame generation circuit 27, which will be described later, for the image pickup signal output from the image pickup device 19 via the amplifier 20.
Has a gate circuit for sampling an image pickup signal corresponding to a predetermined photometric area set in the screen based on the command of 1. and the IG driver 16 so that the luminance level of the video signal in the photometric area becomes constant. It is an aperture control circuit for controlling and driving the IG meter 15 and adjusting the aperture amount of the aperture 10 to appropriately maintain the imaging light amount.

In the aperture control circuit 25, there are provided a gate circuit for sampling an image pickup signal corresponding to the photometric area, an integrating circuit for obtaining an average value of the brightness levels of the image pickup signal in the photometric area, and the like. include.

The aperture control can be partial or spot photometry if only the image pickup signal in the photometry area is used.
If the weighting of the signal in the photometric area is increased and the weight of the area other than the photometric area is decreased and the average is taken, center-weighted photometry is performed. Furthermore, if a plurality of photometric areas are set on the screen and a plurality of weights are applied to each, so-called multi-division photometry is performed.

Reference numeral 26 denotes an AF evaluation value processing circuit for generating a focus evaluation signal such as a high frequency component whose level changes in accordance with the focus state from the image pickup signal output from the image pickup device 19 via the amplifier 20. Is.

In the AF evaluation value processing circuit 26, a band pass filter for extracting the high frequency component in the image pickup signal, and a predetermined focus detection set on the screen based on a command from a frame generation circuit described later. A gate circuit is provided for passing and sampling only the image pickup signal corresponding to the area, that is, the focus detection area (distance measuring area).

Reference numeral 27 denotes a frame for generating a gate signal for controlling the opening / closing timing of the gate circuits provided in the AF evaluation value processing circuit 26 and the aperture control circuit 25 for setting the focus detection area and the photometric area, respectively. By controlling the opening and closing timing of each of the gate circuits in the generation circuit,
It is possible to freely set the position and size of the capture area when capturing the image information of the imaging screen.

Further, the frame generation circuit 27 outputs an area display signal to the LCD display circuit 23 in order to display the focus detection area and the photometric area on the window of the finder, whereby the video signal from the amplifier 22 is focused. Display signals of the detection area and the photometry area can be superimposed and displayed on the screen of the electronic viewfinder 24.

Reference numeral 29 controls the focus compensating lens based on the output signal of the AF evaluation value processing circuit 26 and the driving of the zoom lens 9 to perform focusing and focus correction at the time of zooming. It is a control microcomputer (hereinafter referred to as a microcomputer) that controls the frame generation circuit 27 to change the positions of the focus detection area and the photometric area in the screen based on the above.

Further, the microcomputer 29 controls the line-of-sight detection circuit 6 and receives information on the line-of-sight position of the operator from the line-of-sight detection circuit 6 to move the focus detection area and the photometric area,
Control using other line-of-sight detection is performed.

Further, 28 is a sensor for detecting the line of sight CC
It is a driver that drives D.

FIG. 2 is a detailed block diagram of the line-of-sight detection device block 1 of FIG. In the figure, blocks having the same functions as those in FIG. 1 will be described with the same numbers as in FIG.

The IRED driver 3 drives the IRED 2 to emit light by the control signal from the visual axis detection circuit 6.
Two IREDs are provided. The infrared light emitted from the IRED 2 is reflected by the eyeball EYE and reaches the dichroic mirror 102 which reflects only the infrared light and transmits the visible light through the eyepiece lens 101.

The reflected infrared light reflected by the dichroic mirror 202 and having its optical path changed is imaged through the imaging lens 103 on the image pickup surface of the CCD image sensor 4 as a visual axis detection sensor. Reference numeral 28 denotes a circuit for driving the CCD image sensor 4, which is driven by a visual axis detection circuit 6 to be described later at a predetermined sampling period to repeatedly perform storage and reading.

The eyeball reflected light incident on the CCD 4 is converted into an electric signal and supplied to the visual axis detection circuit 6 via the amplifier 5. The eyeball EYE is looking at the display screen of the electronic viewfinder 24, and the image pickup screen of the CCD 4 and the screen of the electronic viewfinder 24 correspond to each other.
If the gazing point in the image capturing screen of No. 4 is obtained, the gazing point in the display screen of the electronic viewfinder 24 can be detected.

With the configuration of this line-of-sight detection block, the line-of-sight detection circuit 6 detects the line-of-sight position coordinates on the display screen of the electronic viewfinder from the output signal of the amplifier 5. The detected line-of-sight position coordinate information is stored in the microcomputer 2
9 is transmitted.

There are various methods for calculating the visual axis position coordinates based on the output of the visual axis CCD 4.
For example, Japanese Patent Application No. 3-218 filed by the present applicant
The method disclosed in Japanese Patent Application No. 574 and Japanese Patent Application No. 4-154165 can be used.

The driving of the CCD 4 and the light emission of the IRED are executed by the line-of-sight detection circuit 6 at a predetermined sampling period, and the gazing point is sampled.

The video-integrated camera having the configuration shown in FIG.
As the AF method, a so-called television AF method (TV-
AF method), that is, a high-frequency component is taken out by a band pass filter in the AF evaluation value processing circuit 26 in the image pickup signal, and the microcomputer 29 drives the focus motor drive direction and drive to maximize the high-frequency component level. A focus adjustment method is used in which the speed is calculated, the focus competition lens motor 17 is driven via the focus competition lens driver 18, and the focus competition lens 12 is moved in the optical axis direction.

In this AF method, since the high frequency component included in the video signal is detected as described above, the video signal taken into the AF evaluation value processing circuit 26 must include the edge portion (level change portion). . That is, at least one horizontal scanning line video signal must be used,
Practically, a capture area having a predetermined area is required. This area is a focus detection area (distance measurement area).

FIG. 3 is a block diagram showing a circuit configuration for performing gate processing for actually fetching a video signal after the focus detection area is defined by the microcomputer 29. The AF evaluation value processing circuit 26 and the frame are mainly shown. 3 illustrates a configuration within a generation circuit 27.

The frame generation circuit 27 gates the video signal output from the amplifier 20 and scans the video signal corresponding to a predetermined position in the screen, and the AF evaluation value processing circuit and the aperture control circuit 25 are operated. The gate circuit is turned on to take out only the signal in the area. In this embodiment, the focus detection area can be formed in the substantially center of the surface and the left and right areas adjacent to both sides thereof.

In FIG. 3, in the AF evaluation value processing circuit 26, an AF gate circuit 263 for setting a main central focus detection area C in the central portion of the screen, and left and right sides of the central focus detection area C, respectively. AF gate circuits 261 and 265 for setting the focus detection areas L and R are provided, and a gate pulse generation circuit 27 in a frame generation circuit 27 described later is provided.
The video signal output from the amplifier 20 is passed to the subsequent circuit only during the period in which it is closed by the respective gate pulses generated by 3, 272 and 274.

AF gate circuits 263, 261, 265
In the subsequent stage, AF evaluation value generation circuits 264, 262, 26 that extract a predetermined signal component that changes depending on the focus state from the extracted video signals and output an AF evaluation value.
6 is connected.

These AF evaluation value generation circuits detect a peak value of a high-frequency component extracted by the band-pass filter and the band-pass filter that detects a high-frequency component that changes according to the focus state in the video signal. In the present embodiment, the peak hold value of the high frequency component and the normalized value obtained by removing the influence of the brightness by dividing the peak hold value of the high frequency component by the brightness difference and normalizing the peak hold value. Shall be output.

As a result, the AF evaluation value processing circuit 26 detects the focus state of the image in the left and right focus detection areas L and R adjacent to both sides of the focus detection area C in the center of the screen. be able to.

AF gate circuits 263, 261, 26
By selectively operating 5, it is possible to select the focus detection area used in the screen,
By changing the opening / closing timing of the AF gate circuits 263, 261 and 266, the position and size of the focus detection area in the screen can be changed.

On the other hand, looking at the internal structure of the frame generation circuit 27, a gate pulse for controlling the opening / closing of the AF gate circuit 263 forming the central focus detection area C in the AF evaluation value processing circuit 26 is generated. A center gate pulse generation circuit 273, a left gate pulse generation circuit 272 that generates a gate pulse for controlling opening and closing of an AF gate circuit 261 that forms a left focus detection area L, and an AF gate circuit 265 that forms a right focus detection area R. A right gate pulse generation circuit 274 for generating a gate pulse for controlling the opening and closing of each is provided, and a frame generation circuit 271 for displaying the central focus detection area on the screen is provided.

Further, based on the information on the size of the focus detection area and the position on the screen supplied from the microcomputer 29,
The central gate pulse generation circuit 273 is controlled to generate a gate pulse for opening / closing the AF gate circuit 263, and the frame generation circuit 271 is caused to generate a frame signal for displaying the central focus detection area on the screen. A gate timing generation circuit 275 for outputting to the circuit 23 is provided.

Similarly, the left gate pulse generation circuit 272 and the left gate pulse generation circuit 272 are respectively supplied based on the information on the size of the focus detection area and the position on the screen supplied from the microcomputer 29.
A gate timing generation circuit 2 that controls the right gate pulse generation circuit 274 to generate a gate pulse for opening and closing the left AF gate circuit 261 and the right AF gate circuit 265.
76,277 are provided.

These gate timing generation circuits 27
Reference numerals 6 and 277 respectively operate so as to form left and right focus detection areas L and R adjacent to the left and right sides of the central focus detection area C, respectively.

With the above-described structure, the central focus detection area and the left and right focus detection areas adjacent to both sides of the central focus detection area are respectively determined based on the information about the size of each focus detection area and the position on the screen supplied from the microcomputer 29. Can be set.

That is, the gate timing generation circuit 275
Generates a frame timing signal by generating a gate timing pulse for setting and displaying the focus detection area at the center of the screen based on the information about the size of the focus detection area and the position on the screen supplied from the microcomputer 29. The frame signal generation circuit 271 transmits the frame display signal to the LCD display circuit 23 based on the gate timing pulse.
And a frame indicating the focus detection area is displayed on the screen of the electronic viewfinder 24 by being superimposed on the video signal from the amplifier 22.

The gate timing pulse output from the gate timing generating circuit 275 is an AF for generating a gate pulse for setting the focus detection area at the center of the screen.
It is also supplied to the gate pulse generation circuit 273, and the AF gate pulse generation circuit 273 uses the gate pulse for setting the central focus detection area C generated based on the gate timing pulse, and the AF gate circuit 26 in the AF evaluation value processing circuit 26.
3 is controlled to be opened and closed so that the AF evaluation value in the central focus detection area C can be captured.

Similarly, the gate timing generation circuits 276, 2 for setting the left and right focus detection areas inside the frame generation circuit 27.
The information about the size and the position of the left and right focus detection areas of the central focus detection area transmitted to the gate timing generation circuit 275 is transmitted from the microcomputer 29 to 77.

Then, the gate timing generation circuit 276,
At 277, based on this information, a gate timing signal is output to the left and right AF gate pulse generation circuits 272 and 274 which generate gate pulses corresponding to the left and right AF capture areas.

As a result, the AF evaluation value generating circuits 264, 262 and 26 are the signals in the center and left and right focus detection areas of the video signal output from the amplifier 20, respectively.
6, the AF evaluation values in the center, left and right focus detection areas can be fetched, and the area display on the screen is performed only for the central focus detection area C.

Although the information on the position and size of each focus detection area may be individually supplied from the microcomputer 29, if the information on the position and size of the central focus detection area C is supplied,
The left and right focus detection areas can be easily set by changing the gate timings of the left and right gate timing generation circuits 276 and 277.

FIG. 4B is a diagram showing an example of a focus detection area for capturing an AF evaluation value which is generally used.

In the figure, 401 is an image pickup screen and 404.
Is a focus detection area for capturing an AF evaluation value.

The photographer often has an opportunity to place a subject (main subject) to be photographed in the center of the screen. Further, as described above, the focus detection area for capturing the AF evaluation value is generally smaller than the entire shooting screen in order to prevent the main subject from being affected by another subject. is there. For this reason, the capture area is fixed at a substantially central position as indicated by 404.

However, the photographer does not always fix the main subject in the center of the screen for photographing, and in order to photograph the main subject not in the center of the screen, the focus detection area must be moved on the photographing screen. I won't.

Therefore, in FIG. 1, on the basis of the line-of-sight position coordinate information transmitted from the line-of-sight detection circuit 6 to the microcomputer 29, the microcomputer 29 moves a frame to move the focus detection area to the position viewed by the photographer. The size and position coordinate information of the focus detection area is transmitted to the generation circuit 27.

In the frame generation circuit 27, as described above, in order to move the focus detection area to the designated position on the screen,
A frame display signal indicating a corresponding part of the focus detection area so as to operate the opening / closing timing of each AF gate circuit in the AF evaluation value control circuit 26 and display the part corresponding to the central focus detection area on the screen of the electronic viewfinder 24. To the LCD display circuit 23.

In the LCD display circuit 23, the video signal from the amplifier 20 and the display signal from the frame generation circuit 27 are superimposed and displayed on the electronic viewfinder 24.

At this time, the appearance of the image displayed on the screen of the electronic viewfinder 24 is shown in FIG. In the figure, 403 is the current viewpoint position of the photographer detected by the line-of-sight detection circuit 6.

A focus detection area for capturing an AF evaluation value such as 402 is set around this position, and the microcomputer 29
From the center AF gate circuit 263 via the frame generation circuit 27
Is operated, and the focus detection area corresponding to the corresponding ON area is displayed as indicated by 402 in FIG. 4A.

Next, for example, when the photographer moves the viewpoint to the position of 405, a capture area centering on 405 is set as 406 by the same method, and the display of 402 is moved to 406.

By taking the method as described above, it is possible to focus on the subject viewed by the photographer. However, in the case of taking good shots with a video camera, appropriate focus adjustment for the subject is performed. Of course, it is desirable to perform exposure adjustment in parallel.

Therefore, in FIG. 1, the frame generation circuit 27 also transmits a signal for setting the focus detection area setting AF capture area to the aperture control circuit 25. As a result, not only in AF but also in AE, it is possible to move the photometric information capturing area to the position viewed by the photographer and perform exposure adjustment based on the photometric information of that portion.

Now, the operation of the present invention will be further described with reference to FIG.

In the figure, 501 and 502 are the same subject, and it is assumed that the subject has moved from 501 to 502 as shown by the arrow.

Reference numerals 503, 504, and 505 denote focus detection areas for fetching AF evaluation values, and 503 is the same area as the central focus detection area displayed on the image pickup screen as described with reference to FIG. Further, as described with reference to FIG. 3, reference numerals 504 and 505 are left and right focus detection areas L and R which are set adjacent to the left and right of the central focus detection area C displayed on the screen.

When the subject is in 501, the subject is located in the focus detection area 503, and even if it is moved to 502, it is still in the capture area 505. Therefore, 50
Even if the AF evaluation value within 3 fluctuates and the AF is erroneously recognized as out of focus, if it can be determined that 505 seems to be in focus, it is possible to immediately prohibit high-speed mountain climbing without performing high-speed mountain climbing and searching. . Therefore, the subject 502 will not be blurred due to the movement of the focus lens toward high-speed mountain climbing.

Next, the algorithm of the AF operation of the present invention will be described with reference to FIG. The same steps as those in FIG. 6 are designated by the same reference numerals.

When the processing is started, the wobbling operation is first performed in step 601, and based on the result, it is determined in step 602 whether the focus is on or out of focus.

As a result, when the subject goes out of the focus detection area displayed on the screen, it does not immediately go into high-speed mountain climbing, especially with respect to the movement in the horizontal direction, and a stable focus is obtained. The detection operation becomes possible. Monitor whether or not

If the result of determination in step 602 is that the image is not in focus but is out of focus, step 605 takes in the above-mentioned normalized value, and step 606 determines in-focus from that value.

If the result of the determination in step 606 is that it is possible to determine the in-focus state, the high-speed mountain climbing operation is not performed, but the process proceeds to step 601 and the wobbling operation is performed again to perform the in-focus determination. By operating in this way, the stability at the time of focusing is increased.

If neither the wobbling determination result nor the normalized value is determined to be in focus in steps 602 and 606, the process proceeds to step 701. This processing is the main point of the present invention.

That is, in step 701, the normalization value obtained by normalizing the AF evaluation values in the left and right focus detection areas L and R not displayed on the screen on both sides of the central focus detection area C by the brightness difference is the focus. If it is determined that the subject is in focus, the process proceeds to step 601 without shifting to the high-speed hill climbing operation.

In other words, if it is determined that the image signal in the central focus detection area C is out of focus, this processing is equivalent to the displayed central focus detection area C (5
03) focus detection areas L and R (50
4, 505), and since the focus detection area is expanded without changing the display, it is possible to stabilize the focus detection without the photographer being aware of it and unnecessary for the photographer. It is possible to reduce a heavy operational burden (for example, consciously changing the gazing point each time the display changes, or an action of strictly gazing at a specific area). This is AF
It is effective not only for stabilizing operation but also for improving operability.

This operation increases the stability when the subject moves as shown in FIG. 5 and leaves the focus detection area.

If neither the wobbling determination result nor the normalization values of the three capture areas are determined to be in focus, a high speed hill climbing is performed in step 607 in the direction of the determination result by the wobbling operation.

Then, in step 608, it is judged whether or not the focal point, that is, the apex of the AF evaluation value is exceeded, and if it is not exceeded, the process returns to step 607 to continue high speed mountain climbing,
If it has exceeded, it returns to the top at 609.

However, since the subject may change due to panning or the like during the operation of returning to the apex, if the focus lens reaches the apex at step 610, the next place is really the apex, that is, the in-focus point. To determine whether or not it returns to 601 and the wobbling operation is performed.

If it is determined in this wobbling operation that the object is in focus, restart monitoring is performed, and if it is determined that the object is not in focus, the high speed hill climbing operation is performed in the direction of the result of the determination. By repeating such operations, the AF operates so as to constantly maintain the in-focus state.

As described above, the in-focus point can be reached even with the wobbling operation.

[0113]

As described above, according to the invention described in claim 1 of the present invention, the main focus detection area displayed on the screen is made variable, and separately outside the focus detection area. By controlling the AF operation based on the information on the set capture area, it is possible to prevent the malfunction of the AF caused by the movement of the capture area or the small capture area.

As a result, a stable focus detection operation is possible even when the subject moves out of the focus detectable range displayed on the screen, or when the subject repeatedly moves in and out near the boundary. .

Further, even if the subject goes out of the focus-detectable range displayed on the displayed screen, the focus adjustment operation is prevented from immediately displacing, and the response characteristic given to the photographer against the out-of-focus condition, Since the response characteristic in the actual focus control operation is different, the operation feeling of the photographer can be stabilized and the burden on the photographer can be reduced.

According to the invention of claim 2 of the present application, the control means controls the range setting means to adjoin the range when the focused state cannot be obtained from the video signal in the range. The video signal corresponding to the predetermined external range is extracted, and the focus detection is performed based on the signal corresponding to the external range, so that the subject exits the focus detection area displayed on the screen. In the case of a streak, there is an effect that a stable focus detection operation can be performed without immediately entering a high-speed hill climbing especially in the movement in the horizontal direction.

Further, according to the invention of claim 3 of the present application, the control means sets an external region to the left and right across the range, extracts a video signal corresponding to the external range, and extracts the video signal within the external range. Since it is configured to control the focus detection based on the signal corresponding to, when the subject goes out of the focus detection area displayed on the screen, especially when moving in the horizontal direction, the speed is increased immediately. There is an effect that a stable focus detection operation can be performed without entering a mountain climbing, the operation feeling of the photographer can be stabilized, and the burden on the photographer can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a line-of-sight detection block 1 in FIG.

3 is a block diagram for explaining a configuration and an operation of an AF evaluation value processing circuit 26 and a frame generation circuit 27 in FIG.

FIG. 4 is a diagram for explaining display of a focus detection area.

FIG. 5 is a diagram for explaining a line-of-sight detection coordinate, a setting state and a display state of a focus detection area.

FIG. 6 is a flowchart showing focus detection processing which is a premise of the present invention.
It is a chart.

FIG. 7 is a flowchart showing the processing of the present invention.

FIG. 8 is a diagram for explaining a wobbling operation.

[Explanation of symbols]

1 Line-of-sight detection block 6 Line-of-sight detection circuit 7 Lens unit 23 LCD display circuit 24 Electronic viewfinder 25 Aperture control circuit 26 AF evaluation value processing circuit 27 Frame generation circuit 29 Microcomputer 261,263,265 AF evaluation value processing circuit 26 gate circuit 262 , 264, 266 AF evaluation value generation circuit 271 Frame generation circuit 272, 273, 274 Left, center, right gate pulse generation circuit 275, 276, 277 Center, left, right gate timing generation circuit

Claims (3)

[Claims] 1. Display means for displaying a video signal on a screen, video signal capturing means for capturing a video signal corresponding to a predetermined range in the screen, range setting means for changing the range, and the range setting An instruction means for controlling the means to change the set position of the range within the screen, and a signal that changes according to the focus state from the video signals within the range captured by the video signal capturing means. Focus detection means for performing focus detection, focus adjustment means for performing focus adjustment based on the output of the focus detection means, and the position within the screen of the range within the video signal displayed by the display means. An operation of the focus adjusting means is controlled on the basis of a range display means for superimposing and displaying, and a video signal corresponding to the outside of the range displayed by the range display means. Imaging apparatus characterized by comprising: a control means. 2. The control means according to claim 1, when the focusing state is not obtained from the video signal in the range, the control means controls the range setting means so that the range is within a predetermined external range adjacent to the range. An image pickup apparatus, which is configured to extract a corresponding video signal and perform control so as to perform focus detection based on a signal corresponding to the outside range. 3. The control means according to claim 2, wherein the control means sets an external region to the left and right across the range, extracts a video signal corresponding to the external range, and outputs a video signal corresponding to the external range. An image pickup apparatus configured to control focus detection based on the above.