JPH11205694A - Photoelectric converting device and focus detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high accuracy at low cost by having plural photoelectric elements that are divided into plural areas, a means which starts storage and a decision means which compares a monitor output with a prescribed value and decides the continuity of storage. SOLUTION: A controller 1 takes charge of storage control over plural sensor strings and reading an image signal and sensor string blocks 2, 3, 4 belong to areas 1, 2, n respectively and correspond to each distance measuring point. In one sensor string block, a pair of sensor arrays constitute a sensor part for a phase difference detection system and a sensor array detects a 1st image with about 30 to 80 pixels and a 2nd image with the same pixel number. It is provided with a peak detection circuit which detects the highest output value during storing and a memory part which temporarily saves photoelectric conversion output that is stored in a sensor part at the same time with when storing is finished. The peak detection circuit outputs the highest value (p-out) in pixels to one inputting part of a compactor 5 when an analog switch 12 is on.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detection device used for a photographing device such as a still camera and a video camera, or various observation devices. Further, the present invention relates to a photoelectric conversion device used therein.

[0002]

2. Description of the Related Art Conventionally, a so-called autofocus camera (hereinafter referred to as A) which detects a focus state of a subject and automatically focuses by changing a distance ring of a photographing lens accordingly.
F camera) and the like have been proposed.

[0003] This AF camera initially has a center 1 in the screen.
Although a method of detecting the focus state of a point has been proposed, recently, the number of points (hereinafter referred to as distance measuring points) for gradually detecting the focus state at three points, four points, and five points on a screen has increased. Since the main subject in the screen is arranged at the distance measuring point, and the framing is not changed after focusing, the usability has been improved.

In order to further improve the usability, it is desirable to further increase the number of distance measuring points.

On the other hand, in order to detect the focus state of the distance measuring point, an image of a subject is formed on a photoelectric conversion device (hereinafter referred to as a sensor) composed of a plurality of pixels, and each pixel signal is subjected to arithmetic processing. At this time, the focus detection can be performed with higher accuracy as the image signal constituted by each pixel signal becomes larger. However, when the image signal is too large, the dynamic range in which the pixel signal can be processed is exceeded, and as a result, the image signal differs from the actual one. Instead, the accuracy will be worse.

Therefore, it is general to use an accumulation type sensor and appropriately control the accumulation time.

[0007] When there are a plurality of ranging points, the accumulation time of the area corresponding to each of the ranging points is controlled independently. The scale of the circuit for appropriately controlling the accumulation time is large, and the circuit scale of the sensor including the control circuit when the number of distance measurement points is increased is enormous. Therefore, the applicant of the present application has already filed Japanese Patent Application No. 8-256288. In Japanese Patent Application Laid-Open No. H10-157, a method is proposed in which a photoelectric conversion element is divided into regions for each ranging point, and the accumulation time is controlled by a single control unit while sequentially scanning each region.

[0008]

However, in this method, since the scanning operation is always performed during the accumulation time, a large amount of noise is generated and the accuracy is deteriorated, or the current consumption increases and energy is wasted. It is possible to do.

On the other hand, if the scanning operation is slowed, the above-mentioned problem can be solved. However, when focus detection is performed on a high-luminance target image, the image signal has a dynamic range during the scanning operation for each area. In some cases, and this also deteriorates the accuracy and makes it impossible to detect the focus, making it difficult to satisfy both. Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a low-cost and accurate photoelectric conversion device and a focus detection device.

[0010]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, a photoelectric conversion device according to the present invention includes a plurality of photoelectric conversion elements divided into a plurality of areas, and an accumulation start unit for starting accumulation of the photoelectric conversion elements in the plurality of areas. Monitoring means for sequentially monitoring and outputting the accumulation state of the photoelectric conversion elements in the respective areas, and comparing the sequentially output monitor outputs with a predetermined value, thereby performing photoelectric conversion of the areas corresponding to the monitor outputs. Determining means for determining whether or not to terminate the accumulation of the element, and terminating the accumulation of the photoelectric conversion element in an area corresponding to the monitor output when the determination means determines that the accumulation should be terminated. And an accumulation ending means for causing the monitoring means to sequentially output the accumulation state in each of the areas at predetermined time intervals, and immediately after the accumulation starts and after a lapse of a while after the accumulation starts. It is characterized by varying the said predetermined time.

Further, in the photoelectric conversion device according to the present invention, a plurality of the photoelectric conversion elements are arranged in each of the plurality of regions.

Further, in the photoelectric conversion device according to the present invention, the plurality of photoelectric conversion elements constitute an area-type sensor having a continuous two-dimensional spread.

Further, in the photoelectric conversion device according to the present invention, the monitor output is a signal based on the maximum amount of accumulated charge in the photoelectric conversion elements included in each area.

Further, in the photoelectric conversion device according to the present invention, the monitor means is characterized in that the predetermined time is made different by providing a wait time at the timing of the monitor output.

Further, in the photoelectric conversion device according to the present invention, the monitor means changes the predetermined time by changing a clock signal for controlling the timing of the monitor output.

Further, the focus detection device according to the present invention comprises: a plurality of photoelectric conversion elements divided into a plurality of areas; an accumulation start means for starting accumulation of the photoelectric conversion elements in the plurality of areas; Monitoring means for sequentially monitoring and outputting the accumulation state of the photoelectric conversion elements in each area; and comparing the monitor outputs output in the order with a predetermined value, whereby the photoelectric conversion elements in the area corresponding to the monitor output are compared. Determining means for determining whether or not to terminate the accumulation; and when the determination means determines that the accumulation should be terminated,
Accumulation ending means for ending the accumulation of the photoelectric conversion element in the area corresponding to the monitor output, pixel reading means for reading each pixel in each of the divided areas, and a signal of each pixel read by the reading means Detecting means for detecting the focus of the object by calculating the following. The monitoring means sequentially monitors and outputs the accumulation state in each of the regions at predetermined time intervals, and immediately and immediately after the accumulation start and the accumulation start It is characterized in that the predetermined time is made different after a lapse of a while.

Further, in the focus detection device according to the present invention, a plurality of the photoelectric conversion elements are arranged in each of the plurality of regions.

Further, in the focus detecting device according to the present invention, the plurality of photoelectric conversion elements constitute an area type sensor having a continuous two-dimensional spread.

Further, in the focus detection device according to the present invention, the monitor output is a signal based on the maximum accumulated charge amount in the photoelectric conversion elements included in each area.

Further, in the focus detection device according to the present invention, the monitor means is characterized in that the predetermined time is made different by providing a wait time at the timing of the monitor output.

Further, in the focus detection device according to the present invention, the monitor means varies the predetermined time by changing a clock signal for controlling the timing of the monitor output.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below. In describing one embodiment, a principle part of a focus detection device will be described with reference to FIGS. explain.

FIG. 7 is a diagram showing a cross section of a camera in which a focus detection device is incorporated.

In the drawing, reference numeral 101 denotes an objective lens for condensing light from an object to be photographed to perform photographing; 102, a semi-transmissive main mirror for reflecting an incident light beam from 101; 103, a focal position of the objective lens 101; , A pentaprism for changing the direction of light rays, 105 an eyepiece for the photographer, 106 a sub-mirror that operates during focus detection, 107 a film such as a silver halide film, and 108 a focus detection device. Is shown.

In this figure, light from a subject (not shown) passes through an objective lens 101, is reflected upward by a main mirror 102, and forms an image on a reticle 103. The image formed on the reticle 103 is reflected by the pentaprism 104 a plurality of times and is visually recognized by the photographer or observer via the eyepiece 105.

On the other hand, from the objective lens 101 to the main mirror 10
A part of the light beam that has reached 2 passes through the main mirror 102, is reflected downward by the sub-mirror 106, and is guided to the focus detection device 108.

FIG. 8 is an expanded view showing only the objective lens 101 and the focus detection device 108 in FIG. 7 for explaining the principle of focus detection.

In the focus detection device 108 shown in FIG.
Reference numeral 09 denotes a field mask disposed near the predetermined focal plane of the objective lens 101, that is, a plane conjugate with the film plane. Reference numeral 110 denotes a field lens also disposed near the predetermined focal plane.
Reference numeral 1 denotes a secondary imaging system including two lenses 111-1 and 111-2, and 112 denotes two lenses 111-1 and 111-2.
And two sensor rows 112 arranged behind the
-1, 112-2, and 113 is a photoelectric conversion element arranged corresponding to the two lenses 111-1, 111-2.
Diaphragm having three openings 113-1 and 113-2, 11
Reference numeral 4 denotes an exit pupil of the objective lens 101 including the two divided regions 114-1 and 114-2.

Incidentally, the field lens 110 is provided in the regions 114-1 and 114- of the exit pupil 114 of the objective lens 101.
2, the apertures 113-1 and 113-
2 has a function of forming an image in the vicinity of the light beam 115-1 and the light flux 115-
1, 115-2 has two sensor rows 112-1, 112-.
2, the light intensity distribution is formed.

The focus detection device shown in FIG. 8 is generally called a phase difference detection system. In FIG. 9, a graph of the light amount distribution formed on the sensor arrays 112-1 and 112-2 is used. explain.

In FIG. 9, reference numeral 201 denotes the intensity of light amount on the vertical axis of the graph. 202 is the horizontal axis of the graph,
-1, 112-2 represents the spread of each pixel.
Reference numerals 07 and 208 represent light intensity outputs (hereinafter, image signals) of the pixels. Reference numerals 203 and 204 denote the spreads of the sensor rows 112-1 and 112-2, respectively, and the first image and the second image
Called the image for convenience. Reference numerals 205 and 206 denote the central portions of the respective sensor rows.

When the image forming point of the objective lens 101 coincides with the expected focal plane, the graph shown in FIG. 9A is obtained, and the image outputs of the first image and the second image substantially coincide.

On the other hand, when the image forming point of the objective lens 101 is in front of the predetermined focal plane, that is, when it is on the objective lens 101 side, as shown in FIG.
The light quantity distributions formed on the respective 1, 112-2 become closer to each other. Conversely, when the image forming point of the objective lens 101 is behind the planned focal plane, the light amount distributions formed on the two sensor arrays 112-1 and 112-2 as shown in FIG. They are separated from each other.

Moreover, the two sensor arrays 112-1 and 112
The deviation amount of the light amount distribution formed on the
Since the defocus amount, that is, the defocus amount, has a certain functional relationship with the defocus amount, the direction and amount of defocus of the objective lens 101 can be detected by calculating the defocus amount by an appropriate calculating means. The position of the lens system such as the objective lens 101 is moved according to the direction and the amount, and the shift amount is set to be substantially zero, and the focus detection operation ends.

In general, an image signal is converted from an analog output from a sensor into an analog-to-digital signal (hereinafter referred to as an AD conversion), and then digitally processed by a processing unit to perform the above-described defocus amount calculation. At this time, it is necessary to perform the accumulation control to the sensor for an appropriate accumulation time and to read the analog output with an appropriate amplification factor (hereinafter referred to as a gain) in order to accurately calculate the defocus amount.

FIG. 10 is a diagram for explaining the condition of the image signal to improve the accuracy.

In the figure, reference numeral 209 denotes the dynamic range of the AD conversion. When the image signal is read out as shown in FIG. 10A, since almost the entire dynamic range of the AD conversion is used, a precise defocus amount calculation is possible even if the image signal has some noise. It is.

On the other hand, in FIG. 10B, the image signal is set to A depending on whether the accumulation time is too long or the readout gain is too large.
It exceeds the dynamic range of D conversion. Therefore, a portion of the image signal having a high light intensity is lost as information to be calculated and causes an error in the defocus amount calculation. Conversely, in FIG. 10C, the height of the image signal is extremely low because the accumulation time is too short or the readout gain is too small. In this case, the influence of noise on the image signal cannot be ignored, and this also causes an error in the defocus amount calculation.

Therefore, appropriately controlling the accumulation time and the readout gain is an important issue in realizing an accurate focus detection device.

The principle of the focus detection apparatus has been described above.

In the photoelectric conversion device and the focus detection device using the same according to one embodiment of the present invention, a plurality of the focus detection devices described above are functionally present in one camera. In the screen 3 of the target image obtained by the photographer looking through the eyepiece 105 as shown by 11
Even when there are 55 distance measurement points 302 in 01, focus detection can be performed on the same principle.

FIG. 1 is an electric circuit block diagram of the focus detection device 108.

Reference numeral 1 denotes a controller which controls accumulation of a plurality of sensor rows and reads out image signals. Reference numerals 2, 3, and 4 denote sensor row blocks of an area 1, an area 2, and an area n (n is an integer of 2 or more), respectively.
1 corresponds to each distance measuring point 302.

In one sensor row block, a pair of sensor arrays constitutes a sensor section because of the phase difference detection method. The sensor array has a first image of about 30 to 80 pixels and a second image of the same number of pixels. An image is being detected. Further, a peak detection circuit for detecting an output value indicating the highest output during accumulation from among the pixels, and a memory unit for temporarily storing the photoelectric conversion output accumulated in the sensor unit upon completion of accumulation. Is arranged.

The peak detection circuit includes an analog switch 12
Is ON, the highest output value (p−
out) to one input of the comparator 5.
The comparator 5 compares the predetermined voltage VR with the p-out signal, and outputs a comp signal to the controller 1.
The comp signal outputs 1 when the p-out signal is larger than VR, that is, when the accumulation should be terminated.

From the memory unit, if the analog switch 11 is turned on, the shift
The output of each pixel is sequentially output to the input of the buffer amplifier 6 according to the t signal. The buffer amplifier 6 outputs a pixel signal from Vout with an appropriate gain.

When the controller 1 outputs the rst signal (reset signal), the electric charges are cleared in the sensor units of all the areas 1 to n, and the accumulation control of all the areas starts from here. Controller 1 has psel-1, pse
1-2, and after outputting psel-n to the n-th area, which is the last area,
Return to 1-1. By outputting this psel-m (m is 1 to n), the analog switch 12 is turned on, so that the peak signal (p-out) is sequentially output from each of the areas 1 to n.
And the controller 1 can determine the peak signal (p−o) from the selected region based on the comp signal.
By determining whether or not (out) exceeds a predetermined level, it is possible to perform accumulation control of continuing or stopping accumulation in the area.

If the comp signal is 1, tran
By outputting the sm signal, the accumulation of the sensor in that area is stopped, and the photoelectric conversion signal of each pixel accumulated on the sensor is transferred to the memory unit. If the comp signal is 0,
The accumulation of the sensor is continued without performing the transfer operation. In addition, if the area has been transferred once, it is needless to say that the transfer is not performed again.

The area transferred to the memory unit is
An area can be selected by a sel-m signal, and an image output can be read by a shift signal.

(First Embodiment) In FIG. 2, a first embodiment of the controller 1 in FIG. 1 will be described in more detail.

Reference numeral 20 denotes a microcomputer (μCO
M) controls the entire electric circuit of the focus detection device 108 (see FIG. 8). Reference numeral 21 denotes a clock generator, which is a clock signal having a constant period (cl).
k) is output. 22 is a counter
Then, the reset signal (RS
When T) arrives, the value of the counter is cleared to zero, then the clk signal from the clock generator 21 is counted up, and the count value (cnt-value)
Is output.

Reference numeral 23 denotes an accumulation time memory for storing the accumulation time of each area. When a reset signal (RST) is received from the microcomputer 20, all memories are cleared to zero. When a trans-m signal corresponding to each area comes from the microcomputer 20, cn at that time is output.
Store t-value in reg-m. In this way, the respective accumulation times of all the areas can be stored individually. The storage time stored here is used for correction of noise of the image signal and the like, but is not directly related to the present invention, and thus detailed description is omitted.

Reference numeral 24 denotes a signal from the comparator 5 in FIG.
The input terminal of the mp signal is shown. As described above, the microcomputer 20 determines whether to output the trans-m signal based on whether the comp signal is 0 or 1.

Numeral 25 indicates the output of the rst signal to each area in FIG. 1, and is responsible for clearing the counter 22 and the accumulation time memory 23 in FIG. I have.

Reference numerals 26, 28, and 30 denote output terminals of the trans-m signal output from the microcomputer 20 to the sensor unit shown in FIG. 1 and control the accumulation time memory shown in FIG. It is responsible for transferring the photoelectrically converted charge to the memory unit.

Reference numerals 27, 29, and 31 denote output terminals of the psel-m signal output from the microcomputer 20 to the analog switch 12 in FIG. Govern

The operation of the microcomputer 20 will be described in detail with reference to the flowchart of FIG.

When the operation starts in step S100, r
The st signal is output (step S101), and the counter 2
2. In addition to clearing the accumulation time memory 23, the charge of the sensor unit in each area is cleared, and accumulation is started. Then, 0 is input to the register sel inside the μCOM 20. The register sel has a meaning of selecting an area for performing image output reading.

Next, the register w-
cnt is cleared to 0 (step S102). The register w-cnt has a meaning of creating a wait time by being counted up later and compared with a predetermined level.

Next, the clk signal is input, and it is determined whether or not the clk signal has risen from 0 to 1 (rising) (step S103). If it has risen, the process proceeds to step S104; otherwise, the process proceeds to step S10.
Stop at 3.

Next, the count value of the counter 22 (cnt
-Value) is input (step S104).

If it is determined in step S105 that the count value is smaller than the predetermined level c1, the process proceeds to step S106.
Proceed to the following.

Next, the register w-cnt is cleared to 0 (step S106).

In step S107, the register sel is increased by one (increment). This operation corresponds to a part in which the accumulation control is sequentially performed for each area.

Next, if the register sel is larger than n,
That is, if the number of areas of the distance measuring point is exceeded, the register se
1 is input to l and the process returns to the area 1 again (step S10).
8, step S109).

In step S108, the register sel is set to n
If not, a psel-m signal is output (step S110). As a result, the accumulation status of the area m, that is, the peak value of the photoelectric conversion amount of the pixels in the area m appears in the p-out output.

When it is determined in step S111 that the area m is sufficiently accumulated, the comparator 5
Since the signal is output as 1, the microcomputer 20
Outputs a trans-m signal, transfers the electric charge of each pixel of the sensor unit in the area m to the memory unit, ends the accumulation (step S112), and returns to step S102. If the degree of accumulation is still insufficient, the comp signal is output as 0, and the process returns to step S102.

On the other hand, in step S105, the count value (c
If (nt-value) is not less than c1, step S1
Proceeding to 13, it is determined whether or not the register w-cnt has reached a predetermined value c2. If it is c2, the process returns to step S106, and the operation as described above is performed.

In step S113, the register w-cnt
If c2 is not c2, the register w-cnt is incremented (incremented) by one in step S114, and the process returns to step S103 to wait for the next rising of the clk signal.

As described above, in the first embodiment, since the cnt-value is small for a while after the accumulation of the sensor is started, the process immediately proceeds from the step S105 to the step S106, and the accumulation for each region from the region 1 to the region n is performed. The determination of the amount is performed in sequence and in synchronization with the rising edge of the clk signal. Then, when the accumulation of the sensor starts for a while and the cnt-value exceeds the predetermined value c1, if the register w-cnt is not counted up to the predetermined value c2, it is not necessary to determine the accumulation amount for each area. The driving frequency for judging the accumulation amount of the sensor is lowered.

As a result, the focus detection operation of a high-brightness target image can be performed with high precision because the image signal can be formed without exceeding the dynamic range, and the overall driving frequency drops, so that noise can be extremely reduced. In addition, current consumption can be greatly reduced. As described above, according to the present embodiment, it is possible to realize an easy-to-use photoelectric conversion device which is accurate and inexpensive and has many distance measurement points, and a focus detection device using the photoelectric conversion device.

(Second Embodiment) The second embodiment differs from the first embodiment only in that the flowchart of FIG. 3 is replaced by FIG.

The operation of the second embodiment will be described with reference to FIG.

First, steps S200 to S20
Step 3 is the same as step S100 to step S103.

In step S204, step S107
Similarly, the register sel is increased by one (increment).

If the value of the register sel is n or smaller than n, the process proceeds to step S210 and the subsequent steps.
When el exceeds n, the process proceeds to step S206.

In step S206, the count value (cnt-value) of the counter 22 is input.

In step S207, if the count value is smaller than the predetermined level c1, the process proceeds to step S208. If the count value is equal to or larger than the predetermined value, the process proceeds to step S213 and the subsequent steps.

In step S208, the register w-cn
Clear t to 0.

Then, in step S209, 1 is input to the register sel, and the process returns to the area 1 again.

Steps S210 to S212 are as follows:
This is the same as steps S110 to S112.

If the count value is equal to or more than c1 in step S207, it is determined whether the value of the register w-cnt has reached a predetermined value c2 (step S213). If it is c2, the process returns to step S208, and the operation as described above is performed.

If the register w-cnt is not c2 in step S213, the register w-cnt is determined in step S214.
cnt is increased by one (increment), and step S
The process returns to step 203 to wait for the next rising of the clk signal.

As described above, in the second embodiment, since cnt-value is small for a while after the accumulation of the sensor is started, the process proceeds to step S208 after step S207. Returning, c without stopping the determination of the accumulation amount of each area from the area 1 to the area n
This is performed in synchronization with the rise of the lk signal. Then, after a certain time has passed since the accumulation of the sensors has started, cnt-value
When e exceeds the predetermined value c1, from the region 1 to the region n, the determination of the storage amount of each region is performed in synchronism with the rise of the clk signal without stopping, but the determination of the storage amount of the last region n is performed. After the end, a wait operation is performed until the register w-cnt is counted up to the predetermined value c2.
Again, this also lowers the drive frequency for determining the storage amount.

In the second embodiment as well, an effect substantially equivalent to that of the first embodiment is obtained, and a photoelectric conversion device which is easy to use because it is accurate, inexpensive, and has many distance measuring points, and a focus detection device using the photoelectric conversion device, realizable.

(Third Embodiment) The third embodiment is similar to the first embodiment.
As compared with the second embodiment, the detailed view of the controller 1 in FIG. 2 is changed as shown in FIG. 5, and the flowcharts in FIGS. 3 and 4 are changed as shown in FIG.

The different parts will be described with reference to FIG.
The frequency divider (divider) divides the frequency of the clk signal from the clock generator 21 and outputs a d-out signal.

Reference numeral 33 denotes a selector, which is a clk signal from the clock generator 21 or d from the divided period 32.
One of the -out signals is selected by the output c-sel signal of the microcomputer 20, and the c-clk signal is output. When c-sel is 0, the clk signal is selected, and when c-sel is 1, the d-out signal is selected.

In FIG. 2, instead of the clk signal input to the microcomputer 20 and the counter 22, the output c-clk signal of the selector 33 is input to each of the components in FIG.

Next, referring to the flowchart of FIG.
The operation of the third embodiment will be described.

Steps S300 to S301 are
This is the same as steps S100 to S101.

In step S302, the count value (cnt-value) of the counter 22 is input.

In steps S303 to S305, if the count value is smaller than the predetermined level c1, c
-Sel output is set to 0. If the count value is equal to or greater than c1, the c-sel output is set to 1.

In step S306, the clk signal is input, and it is determined whether the clk signal has risen from 0 to 1. If so, step S307
The process proceeds to step S306, but otherwise stops at step S306.

Steps S307 to S312 are
This is the same as steps S107 to S112.

As described above, in the third embodiment, cnt-value is small for a while after the accumulation of the sensor is started, so that c-sel becomes 0 and the output c-c from the selector 33 is obtained.
The clk signal is selected as the lk signal. Then, since the clk signal is input to both the microcomputer 20 and the counter 22, the successive area selection for the accumulation determination is driven by the signal from the clock generator 21 and is driven at a fast cycle.

On the other hand, when a certain period of time has passed since the start of the accumulation and cnt-value exceeds a predetermined value c1, c-sel becomes 1 and the output c-sel from the selector 33 becomes c-sel.
As the clk signal, a d-out signal is selected. Therefore, the driving frequency of the accumulation control becomes slow. At the same time, the accumulation time counter counts up rapidly for a while after the start of accumulation, but slows down after a while.

In the third embodiment, almost the same effects as those in the first and second embodiments can be obtained, and the flowchart is simplified and the load of software is reduced.

The present invention can be applied to a modification or a modification of the above embodiment without departing from the gist of the invention.

For example, in the above example, the explanation has been made by limiting the camera to the camera. However, the present invention is not limited to this, and can be applied to other devices having a focus detection function. Further, at a certain point where the accumulation time has elapsed, the drive frequency for judging the accumulation amount is changed. However, the drive frequency may be changed continuously and gradually. Also, the description has been given of the case where the phase difference detection method is used.

Note that a plurality of photoelectric conversion elements represent sensor units in the sensor row blocks 2, 3, and 4 in FIG. 1, and a plurality of regions are the sensor row blocks 2, 3, and 4 in FIG. And the distance measuring point 3 as described with reference to FIG.
02. The accumulation control means includes a controller 1 and a psel driving the sensor array blocks 2, 3, and 4 in FIG.
-M signal, trans-m signal, etc.
This is described by the movement of steps S110 to S112 and the like.

The storage start means is the rst signal in FIG. 1 or the operation in step S101 in FIG.

The monitoring means is the p-out signal in FIG. 1, and the judging means is described with reference to the comp output of the comparator 5 in FIG. 1 and step S111 in FIG.

The storage ending means is trans-m in FIG.
The signal corresponds to step S112 in FIG.

The difference between the predetermined time intervals immediately after the start of the accumulation and after a while after the start of the accumulation is described in the flowchart of FIG.

[0106]

As described above, according to the present invention, since the driving frequency of the accumulation control is changed after a while after the start of the accumulation, the focus detection operation of the high-brightness target image is not affected by the image signal. Because it can be formed without exceeding the dynamic range, it can be done with high accuracy, and because the overall drive frequency drops, noise can be extremely reduced, and current consumption can be greatly reduced. Therefore, an easy-to-use photoelectric conversion device and a focus detection device using the same can be realized.

[0107]

[Brief description of the drawings]

FIG. 1 is an electric circuit block diagram of a focus detection device.

FIG. 2 is a diagram showing a first embodiment of the controller in FIG. 1;

FIG. 3 is a flowchart for explaining the operation of the first embodiment.

FIG. 4 is a flowchart for explaining the operation of the second embodiment.

FIG. 5 is a diagram showing another example of the controller in FIG. 1;

FIG. 6 is a flowchart for explaining the operation of the third embodiment.

FIG. 7 is a diagram for explaining the principle of the focus detection device.

FIG. 8 is a diagram for explaining the principle of the focus detection device.

FIG. 9 is a diagram showing a light quantity distribution of light incident on two sensors.

FIG. 10 is a diagram illustrating a relationship between a dynamic range of an AD converter and an image signal.

FIG. 11 is a diagram showing distance measuring points in a screen.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Controller 2, 3, 4 Sensor row block 20 Microcomputer 21 Clock generator 22 Counter

Claims (12)

[Claims] A plurality of photoelectric conversion elements divided into a plurality of areas; an accumulation start unit for starting accumulation of the photoelectric conversion elements in the plurality of areas; and an accumulation of photoelectric conversion elements in each of the areas. Monitoring means for sequentially outputting the state in a monitor, and comparing the sequentially output monitor output with a predetermined value to determine whether or not the accumulation of the photoelectric conversion elements in an area corresponding to the monitor output should be terminated. A monitor, comprising: a determination unit for determining; and a storage ending unit for ending storage of a photoelectric conversion element in an area corresponding to the monitor output when the determination unit determines that storage should be terminated, The means is arranged to monitor and output the accumulation state in each area in order at predetermined time intervals, and to make the predetermined time period different between immediately after the accumulation start and after a while after the accumulation start. The photoelectric conversion device according to symptoms. 2. The photoelectric conversion device according to claim 1, wherein a plurality of said photoelectric conversion elements are arranged in each of said plurality of regions. 3. The photoelectric conversion device according to claim 1, wherein the plurality of photoelectric conversion elements constitute an area-type sensor having a continuous two-dimensional spread. 4. The photoelectric conversion device according to claim 1, wherein the monitor output is a signal based on a maximum accumulated charge amount among photoelectric conversion elements included in each area. 5. The photoelectric conversion device according to claim 1, wherein the monitor means makes the predetermined time different by providing a waiting time at the timing of the monitor output. 6. The photoelectric conversion device according to claim 1, wherein the monitor changes the predetermined time by changing a clock signal that controls the timing of the monitor output. 7. A plurality of photoelectric conversion elements divided into a plurality of areas, accumulation start means for starting accumulation of the photoelectric conversion elements in the plurality of areas, and accumulation of the photoelectric conversion elements in each of the areas Monitoring means for sequentially outputting the state in a monitor, and comparing the sequentially output monitor output with a predetermined value to determine whether or not the accumulation of the photoelectric conversion elements in an area corresponding to the monitor output should be terminated. Determining means for determining; storage ending means for ending storage of a photoelectric conversion element in an area corresponding to the monitor output when the determination means determines that storage should be terminated; Pixel readout means for reading out each pixel in the area of, and detection means for detecting the focus of the subject by calculating the signal of each pixel read out by the readout means, The monitor means monitors the accumulation state in each of the areas in order at predetermined time intervals, and varies the predetermined time immediately after the accumulation is started and after a while after the accumulation is started. Focus detection device. 8. The focus detection device according to claim 7, wherein a plurality of said photoelectric conversion elements are arranged in each of said plurality of regions. 9. The focus detection device according to claim 7, wherein the plurality of photoelectric conversion elements constitute an area-type sensor having a continuous two-dimensional spread. 10. The focus detection device according to claim 7, wherein the monitor output is a signal based on a maximum amount of accumulated charge in photoelectric conversion elements included in each area. 11. The focus detection apparatus according to claim 7, wherein the monitor means makes the predetermined time different by providing a waiting time at the timing of the monitor output. 12. The focus detection apparatus according to claim 7, wherein the monitor changes the predetermined time by changing a clock signal that controls the timing of the monitor output.