JP3302132B2 - Imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a focus adjustment by the imaging signal
The present invention relates to an imaging device that performs a joint .

[0002]

2. Description of the Related Art While many distance measuring methods for performing autofocusing have been proposed, an autocorrelation method for obtaining an autocorrelation from image information of an image pickup device such as a CCD for photographing and performing distance measurement has been proposed. I have. The principle will be briefly described.

FIG. 6 is a schematic view of a main part of a focusing means based on an autocorrelation method. Reference numeral 131 denotes a lens, and 133, an image pickup element, which is formed of a photoelectric conversion element such as a CCD. FIG. 7 shows a case where the image sensor 133 is at the in-focus position. 1
32 is a light blocking member (aperture) having two openings,
The pupil of the lens 131 is divided into two regions 63 and 64 by being arranged in the optical path so that the pupil of the lens 131 can be inserted into and removed from the optical path. And the pupil may be divided into three or more parts to obtain three or more pieces of image information.) Numeral 61 indicates the position of the image sensor 133 when the lens 131 is in the back focus state, and numeral 62 indicates the position of the image sensor 133 when the lens 131 is in the front focus state. Normally, the lens side moves, and the position of the image sensor 133 indicates a relative position with respect to the lens 131.

When the lens 131 is in focus, the light beam passing through the pupil region 63 and the light beam passing through the pupil region 64 form an image at the same image position 65 on the surface of the image sensor 133. When the lens 131 is in the back focus state, the pupil region 6
The light beam that has passed through the imaging unit 133 is located at the position 61.
The light flux that has passed through the pupil region 64 at the image forming position 66 is also slightly focused on the image forming position 67 of the image sensor 133. When the lens 131 is in the front focus state, the pupil region 6
3 passes through the image sensor 133 at the position 62.
The light beam that has passed through the pupil region 64 at the image forming position 69 is also slightly blurred at the image forming position 68 of the image sensor 133. FIG. 8 shows an example of the subject image. (A) is an image in focus, and (b) is an image in a blurred state.
Partly overlapped.

[0005] By calculating the autocorrelation based on the subject image formed on the surface of the image sensor 133, the lens 1
It is possible to estimate whether or not 31 is in focus, and if it is not in focus, how much the defocus amount is.

That is, a signal based on a subject image formed on the surface of the image sensor 133 is output by scanning as an electric signal having the time axis t as a variable. Assuming that this signal is x (t), the autocorrelation C (τ) is expressed by the following equation.

[0007]

(Equation 1)

The result of the calculation according to the equation (1) is further converted to C (0)
Then, the autocorrelation coefficient C (τ) having the maximum value 1 at τ = 0 can be obtained.

FIG. 7 shows an example of the autocorrelation coefficient C (τ) thus obtained. In the example shown in FIG.
(Τ) has three peaks a, b, and c, respectively. Here, a is the position of τ = 0 and always takes the maximum value. In a state where the focus is out of focus, a peak appears at a position corresponding to the amount of defocus other than the a. When τ corresponding to the maximum peak position excluding the peak of a is obtained, τ in b
b is obtained. τb indicates that there is a strong correlation at the pixel interval corresponding to the transfer time of the image sensor 133, and this pixel interval is the interval between points 66 to 67 or points 68 to 69 on the surface of the image sensor 133 in FIG. And is called a phase difference. In an actual image, as shown in FIG. 8B, the interval is a double image.

The detection of the direction of the focus shift is performed by the lens 131.
Can be determined by making the pupil diameters of the regions 63 and 64 that divide the pupil into two different. For example, if the pupil diameter of the region 63 is set smaller than the pupil diameter of the region 64, the light beam passing through the pupil region 63 is weaker than the light beam passing through the pupil region 64, and the light beam passing through the pupil region 63 is weaker. Since the number of blurs is reduced and the edge width is reduced, an image indicated by 81 in FIG. 8B is obtained. Conversely, the light flux passing through the pupil region 64 is bright and greatly blurred, and the edge width is increased. Image. When the image sensor 133 is in the state of the position 61, that is, in the rear focus state, when the position 66 is i and the position 67 is j, the magnitude relation of the output signal x of the image sensor 133 is x (i) <x (j). On the other hand, when the image sensor 133 is at the position 62, that is, the front focus, if the position 68 is k and the position 69 is 1, x (k)> x (l). That is, the imaging device 13 depends on whether it is a front focus or a rear focus.
The relative intensities of the signal i, k at the position above 3 and the signal j, l at the position below 3 are reversed. Thus, the front pin and the rear pin can be distinguished.

As described above, by calculating the peak of the autocorrelation of the image information by calculation, the distance between the subject images based on the luminous flux passing through different pupil regions formed on the surface of the image pickup device 133 is determined, and this distance is determined by the lens. By performing conversion using the focal length of 131, the amount of defocus is obtained. Further, the direction of the focus shift can be obtained from the signal output of the image sensor 133 at that time. The video camera can perform a focusing operation by moving the lens 131 on the optical axis based on the focus shift amount and the focus shift direction thus obtained.

As described above, in the autocorrelation method, distance measurement information can be obtained from an image formed on an image sensor, and only one image is required for the image, and instantaneous distance measurement can be performed. It is a feature.

[0013]

However, conventionally, when distance measurement is performed by the autocorrelation method, FIG.
It is necessary to insert and remove a stop having a plurality of apertures different from a normal stop on the optical path, as shown in FIG. 8, and when out of focus, a multiple image as shown in FIG. I will. This means that still camera for still image shooting, when performing autofocus by autocorrelation method, squeezed with normal one opening upon release (in FIG. 5 (b), (c)
There is no problem by returning to (Ref.), But when used in a video camera or the like for capturing moving images, there is a problem that a multiplex image due to the aperture at the time of distance measurement is reflected in the captured moving image.

In many cases, the amount of exposure also changes by changing the number of apertures of the aperture, and even if the shutter speed is adjusted only for the image of the distance measurement aperture, the brightness may change slightly. Regarding the exposure before the start of the distance measurement and the exposure after the end of the distance measurement, when the aperture is returned to the normal aperture having one opening after the end of the distance measurement, the exposure is readjusted by the photometry means.
It is difficult to immediately set the same exposure as before the start of ranging,
Exposure may change between images immediately before the start of ranging and immediately after the end of ranging.

As described above, at the time of moving image shooting, at least one screen of a multiple image is generated, and the exposure changes during and before and after the distance measurement. There is a problem that the image becomes unsightly. In addition, the video from the image sensor is also output on the electronic viewfinder at the time of shooting, but there is a problem that the photographer cannot perform comfortable shooting for the same reason as described above.

The present invention has been made in view of the above circumstances.
To capture the image signal from the imaging means that receives the subject light.
To form a focus adjustment signal,
Provide an imaging device capable of performing display and recording properly.
It is intended to be.

[0017]

Means for Solving the Problems] To achieve the above object, the present invention is Ta outputs an image signal by receiving the object light
Image means and an image signal from the image pickup means,
Focus adjustment signal forming means for forming a point adjustment signal;
Prior to the image signal captured by the point adjustment signal forming means,
Storage means for storing an image signal output from the image means;
An image signal from the imaging means is used as a display signal of the display means.
And an image signal captured by the focus adjustment signal forming means.
The signal is recorded in the storage means without being used as a display signal of the display means.
Control of using the stored image signal as a display signal of the display means
And an imaging device having the means.

Also, the present invention provides a method of receiving object light and receiving an image signal.
Means for outputting a signal, and an image signal from the imaging means
Adjustment signal formation that takes in the image and forms a focus adjustment signal
Means and an image signal captured by the focus adjustment signal forming means
Storing the image signal output from the imaging unit earlier.
Storage means for storing image signals from the imaging means
And the focus adjustment signal forming means is
The image signal to be captured is not the recording signal of the recording means but
The image signal stored in the storage means is recorded by the recording means.
An imaging device having control means for converting a signal.
You.

Further , the present invention provides a method of receiving object light and receiving image light.
Means for outputting a signal, and an image signal from the imaging means
Adjustment signal formation that takes in the image and forms a focus adjustment signal
Means and an image signal captured by the focus adjustment signal forming means
Earlier based on the image signal output from the imaging means
To set the exposure control value, and the focus adjustment signal forming means
After the image signal is captured from the imaging means,
Exposure control means for performing exposure control in accordance with the exposure control value
And an imaging device having:

[0020]

The present invention will be described in more detail with reference to the following examples.

FIG. 1 is a diagram showing the configuration of a "video camera" according to the embodiment. As shown in the figure, a diaphragm device 132 is provided behind the lens 131 as a light shielding member whose number of apertures can be switched, as shown in FIGS. In this embodiment, for the purpose of taking a moving image, the diaphragm device 132 is used only as a diaphragm for switching the number of openings and the exposure amount, and the shutter uses an electronic shutter of the CCD 133 serving as an image sensor.

A driving device 134 has a lens 131 whose focal distance can be varied.
1 from the CCD 133 through the aperture device 132.
The CCD 133 converts the formed image into a video signal. The A / D converter 135 performs A / D conversion so that the frame memory 136 and the microprocessor 138 can read the video signal. The frame memory 136 is capable of temporarily storing at least one screen of the video signal from the CCD 133 passed through the A / D converter 135, and the stored content is stored in the D / A converter 1
The signal is output to the switch 139 through 37.

The switch 139 selects either a direct signal from the CCD 133 or a signal from the CCD 133 temporarily stored in the frame memory 136 in accordance with a command from the microprocessor 138, and passes through the signal processing device 141. The data is output to the recording device 142 and the electronic viewfinder 143. The signal processing device 141 performs signal processing necessary for the video signal, that is, the switch 139.
Video signal processing, such as converting a signal from an image signal into a signal such as a luminance signal and a color difference signal. The recording device 142 is a recording device for recording a moving image using a recording medium such as a magnetic tape. The electronic viewfinder 143 allows the photographer to see the image captured by the video camera.

A microprocessor 138 is a CPU that controls the overall control of the video camera.
A command is sent to the CCD 133, the driving device 134, the switch 139, and the like. The microprocessor 138 has a memory 140 for executing a program.
The video signal passed through the D converter 135 is read, and auto-correlation calculation is performed to obtain distance measurement information.
A so that it can return to the original state when switching the opening of
It is configured to record an aperture value and an electronic shutter speed value by E (automatic exposure control).

Next, the configuration and operation of the aperture device 132 capable of switching the number of apertures will be described with reference to FIGS.

3 and 4, reference numeral 11 denotes a stepping motor for driving the aperture blades, which is fixed to the main plate 16. Reference numeral 12 denotes a pinion gear press-fitted into the rotation shaft 11a of the stepping motor 11,
Diaphragm plate 1 rotatably fitted and supported on the shaft 16b of No. 6
3 is engaged. Reference numerals 14 and 15 denote aperture blades.
Reference numerals a, 14b, 15a, and 15b denote openings formed therein, which change into a state having one opening and a state having two openings depending on the degree of overlap of the aperture blades. When one aperture is provided, the aperture diameter is determined according to the degree of overlap of the aperture blades.

Reference numerals 14c and 15c denote elongated holes formed in these diaphragm blades, and a pair of projections 13a and 13a of the diaphragm plate 13.
13b. The aperture blades 14 and 15 are opposite to each other with the rotation of the aperture plate 13 by fitting the shafts 16b and 16c of the main plate 16 into long holes formed on the left and right of the openings 14a and 14b and 15a and 15b, respectively. To slide in the direction of. Reference numeral 16a denotes a fixed aperture opening formed in the base plate 16.

FIG. 5 is a view showing the state of the aperture of the stop, and the hatched portion indicates the shape of the aperture. (A) is the state of the distance measurement aperture, (b) is fully closed, (c) is the middle aperture,
(D) shows an open state. The overlapping portions of the apertures 14a, 14b of the aperture blades 14, 15 and the apertures 15a, 15b and the aperture 16a fixed to the base plate 16 form an aperture through which actual light passes. By rotating the stepping motor 11, the shape of the opening changes from the state of the distance-measuring diaphragm of FIG. 5A to the fully-closed state of FIG.
The aperture is changed to an intermediate aperture of (c) and an open aperture of (d).

The operation of the video camera according to the present embodiment configured as described above will be described with reference to FIG.

In a normal photographing state, light from the lens 131 is imaged through the aperture device 132 having one opening. The video camera obtains an appropriate aperture value and shutter speed from exposure information of a photometric unit (not shown), and controls the electronic shutter of the CCD 133 by opening the aperture diameter with the aperture device 132 to the aperture value. Thereafter, the stop diameter of the stop device 132 is changed in accordance with the change in the exposure information from the photometric unit. With these controls, the subject is exposed to the image sensor 133 with an appropriate exposure value. The switch 139 is a CCD 133
Side is selected, and the video taken as it is at that time is output to the recording device 142 and the electronic viewfinder 143 through the signal processing device 141.

Next, the operation at the time of the distance measurement state by the autocorrelation method will be described with reference to the flowchart of FIG.

Input by the photographer using the AF operation switch,
Auto-correlation auto-focusing is started by a method such as automatically determining the out-of-focus state due to the movement of a subject by using other distance measurement methods (for example, a hill-climbing method for evaluating the sharpness of an image). This is the start S1.

Immediately after the start S1, in the same state as a normal photographing state, an aperture value as shown in FIGS. 5 (c) and 5 (d) is set with an appropriate aperture value based on exposure information obtained by a photometer (not shown). The part is one normal aperture. In this state,
In S2, the image captured by the CCD 133 is first recorded in the frame memory 136. At the same time, in S3, the aperture value and the shutter speed, which are the exposure at this time, are stored in the memory 140 of the microprocessor 138. At this time, the shutter speeds when the aperture is in the range-finding aperture state are also calculated and stored.

At S4, the switch 139 is set to the frame memory 13
By switching to the 6 side, the image captured in the state of the distance measurement aperture (FIG. 5A) is prevented from being sent to the recording device 142 and the electronic viewfinder 143.
5 instead, the already stored image is stored in the frame memory 13.
6 through the D / A converter 137 and the switch 139 so that the image is output to the recording device 142 and the electronic viewfinder 143.

In step S6, the aperture device 132 is driven to bring the aperture into two distance measurement aperture states (FIG. 5A), and in step S3 the shutter speed is calculated in advance. Next S7
Then, in order to perform an autocorrelation operation using an image photographed in the range-finding aperture state, image data photographed at this time is read into the memory 140 through the microprocessor 138. At this time, what is recorded on the recording means 142 and displayed on the electronic viewfinder 143 is an image read from the frame memory 136. At the same time as reading the image data into the memory 140, in S8,
The aperture value stored in S3 reads the aperture value and shutter speed in one normal aperture state, and the two settings are restored by driving the aperture device 132 and controlling the CCD 133. Then, in S9, the switch 139 is returned to the CCD 133 side.

Then, in S10, the microprocessor 138 performs an autocorrelation operation using the image data read in S7 to obtain a phase difference as defocus information. The in-focus position is obtained by the above operation, and the next S
In step 11, the lens 131 is moved to the in-focus position by the driving device 134 to obtain the in-focus state S12.

It is to be noted that the microprocessor 138 can be processed in parallel, or the apparatus can be configured to use two processors for control and autocorrelation calculation, thereby achieving S8.
9 and S10-11 can be executed simultaneously, and a focused state can be obtained more quickly.

In this embodiment, the stepping motor 11
The apparatus is configured such that the switching speed of the number of apertures of the diaphragm device 132 corresponding to the speed can be completed within the V blanking period, thereby reading out from the frame memory 136 in the moving image to be recorded. The number of images can be reduced, and the effect on the images during operation of the aperture blades 14 and 15 can be prevented.

As described above, according to the present embodiment, only the image data of the multiplex image photographed in the range-finding aperture state is replaced with the image passed through the normal aperture immediately before, and the range-finding is performed using the exposure value immediately before the range-finding. Exposure is performed immediately after the end, so that the moving images to be recorded can be smoothly connected. In addition, there is an effect that the photographer does not suddenly change the screen due to the distance measurement operation and does not give any discomfort.

Although the embodiment has the recording device and the electronic viewfinder, the present invention is not limited to this. For example, the recording device is not provided, and a signal which has been subjected to required video signal processing is processed. It is also possible to directly output to a line, or to monitor an image on an external monitor without an electronic viewfinder and remotely control a video camera.

[0041]

As described above , according to the present invention,
Captures image signals from imaging means that receives subject light
Display of the image signal even when a focus adjustment signal is formed by
Imaging apparatus capable of appropriately performing recording and recording
Things.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

FIG. 2 is a flowchart showing the operation of the embodiment.

FIG. 3 is a perspective view of a diaphragm device used in the embodiment.

FIG. 4 is a schematic diagram showing a positional relationship of each element of a diaphragm device used in the embodiment.

FIG. 5 is an explanatory diagram of an aperture shape of a diaphragm device used in the embodiment.

FIG. 6 is an explanatory diagram of a distance measurement method using autocorrelation.

FIG. 7 shows an example of an autocorrelation coefficient.

FIG. 8 is a diagram showing an example of an image passing through a diaphragm for distance measurement.

[Explanation of symbols]

 131 lens 132 aperture device 133 image sensor 136 frame memory 138 microprocessor 139 switch 140 memory

Claims (22)

(57) [Claims] An image pickup device for receiving an object light and outputting an image signal.
Image means and an image signal from the image pickup means,
Focus adjustment signal forming means for forming a point adjustment signal;
Prior to the image signal captured by the point adjustment signal forming means,
Storage means for storing an image signal output from the image means;
An image signal from the imaging means is used as a display signal of the display means.
And an image signal captured by the focus adjustment signal forming means.
The signal is recorded in the storage means without being used as a display signal of the display means.
Control of using the stored image signal as a display signal of the display means
And an imaging device. 2. An image pickup apparatus which receives an object light and outputs an image signal.
Image means and an image signal from the image pickup means,
Focus adjustment signal forming means for forming a point adjustment signal;
Prior to the image signal captured by the point adjustment signal forming means,
Storage means for storing an image signal output from the image means;
The image signal from the imaging means is used as a recording signal of the recording means.
And an image signal captured by the focus adjustment signal forming means.
The signal is recorded in the storage means without being used as the recording signal of the recording means.
Control of using a stored image signal as a recording signal of the recording unit
And an imaging device. 3. The image forming apparatus according to claim 2, wherein the focus adjustment signal forming unit converts the image signal into
For guiding the subject light when capturing to the imaging means.
Optical path setting means for setting an optical path for forming a predetermined focus adjustment signal
The imaging according to claim 1 or 2, wherein
apparatus. 4. The optical path setting means is a diaphragm.
The imaging device according to claim 3, wherein: 5. The image forming apparatus according to claim 1, wherein the focus adjustment signal forming unit converts the image signal into
For guiding the subject light when capturing to the imaging means.
The light path for forming a predetermined focus adjustment signal and the
Selectively set an imaging optical path to be guided to the imaging means.
2. An optical path setting means, comprising:
2. The imaging device according to 2. 6. The optical path setting means may be an aperture.
The imaging device according to claim 5, wherein: 7. The focus according to a moving position, wherein
Optical path for adjusting signal formation Set the aperture and the shooting light
Switching a diaphragm opening for setting a path.
Item 7. The imaging device according to Item 6. 8. The light source for forming the focus adjustment signal, wherein:
An aperture for setting a path and an optical path for setting
The opening of the same diaphragm blade
The imaging device according to claim 6 or 7. 9. The imaging apparatus according to claim 9, wherein the focus adjustment signal forming unit is configured to perform the imaging
Focus by autocorrelation method based on image signal from means
9. The method according to claim 1, wherein the control signal is formed.
An imaging device according to any of the preceding claims. 10. A method according to claim 1, wherein said focus adjustment signal forming means comprises:
In response to an image signal capture start instruction from the imaging means.
And the control unit controls an image output from the imaging unit.
Storing the signal in the storage means and adjusting the focus
The signal forming means is then output from the imaging means
Capturing an image signal to form the focus adjustment signal
The imaging device according to any one of claims 1 to 9,
Place. 11. The image processing device according to claim 11, wherein
The exposure control value at that time in response to the start command
The imaging device according to claim 10, wherein: 12. The control means according to claim 11, wherein
The aperture value at that time in response to the start command
The imaging device according to claim 10, wherein: 13. The image processing device according to claim 1, wherein
In response to the start command and memorize the current shutter time
The imaging device according to claim 10, wherein: 14. The control means according to claim 1, wherein
Opening of an image signal from the imaging means to the generating means
In response to the start instruction, memorize the exposure control value at that time
The imaging device according to any one of claims 1 to 9,
Place. 15. The control means according to claim 11, wherein
Opening of an image signal from the imaging means to the generating means
In response to the start instruction, it memorizes the aperture value at that time.
The imaging device according to claim 1. 16. The control means according to claim 1, wherein
Opening of an image signal from the imaging means to the generating means
In response to the start command, the shutter time at that time is Remember
The imaging device according to claim 1, wherein
Place. 17. The method according to claim 17, wherein the control unit is configured to output the focus adjustment signal.
Opening of an image signal from the imaging means to the generating means
In response to the start command, memorize the aperture value at that time and
An aperture for setting an optical path for forming a focus adjustment signal,
The focus adjustment signal forming means outputs an image signal from the imaging means.
After capturing the number,
The aperture is used to set the optical path for recording.
The imaging device according to claim 6. 18. The focus adjustment signal forming means.
Focus adjustment according to the adjusted focus adjustment signal
18. The method according to claim 1, further comprising a knot means.
Imaging device. 19. The control means according to claim 16, wherein
Storage means for image signals not captured by
And without using a display signal of the display means
The imaging device according to claim 1. 20. The control device according to claim 17, wherein
Storage means for image signals not captured by
The recording signal of the recording means without passing through
The imaging device according to claim 2, wherein: 21. An object signal is received and an image signal is output.
Capturing an image signal from the imaging unit and the imaging unit;
A focus adjustment signal forming means for forming a focus adjustment signal;
Before the image signal captured by the focus adjustment signal forming means,
Exposure control value based on the image signal output from the imaging means
And the focus adjustment signal forming means is the imaging means
Exposure control values set above after capturing these image signals
Exposure control means for performing exposure control in accordance with
An imaging device characterized by the following. 22. The exposure control means, comprising:
Capture of an image signal from the imaging means to the signal forming means
In response to the start command, the aperture value at that time is memorized.
At the time when the focus adjustment signal forming means captures an image signal.
A predetermined focus for guiding subject light to the imaging means
An aperture for setting an optical path for node signal formation;
An adjustment signal forming means receives an image signal from the imaging means.
After taking the image, the optical path for shooting according to the stored aperture value
3. An aperture for setting the aperture.
The imaging device according to 1.