JP4175582B2 - Photoelectric conversion device and focus detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a focus detection device used for a photographing device such as a still camera or a video camera, or various observation devices. Furthermore, it is related with the photoelectric conversion apparatus used for it.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, various so-called autofocus cameras (hereinafter referred to as AF cameras) and the like have been proposed in which a focus state of a subject is detected and a distance ring of a photographic lens is changed accordingly to automatically focus.
[0003]
This AF camera was initially proposed to detect the focus state at one central point in the screen, but recently, the point for gradually detecting the focus state (3 points, 4 points, and 5 points in the screen) The number of distance measuring points) has increased, and the photographer has improved the usability because the main subject in the screen is placed at the distance measuring point and the framing is not changed before the shooting is performed.
[0004]
In order to further improve usability, it is desirable to increase the number of distance measuring points.
[0005]
On the other hand, in order to detect the focus state of a distance measuring point, an image of a subject is connected to a photoelectric conversion device (hereinafter referred to as a sensor) composed of a plurality of pixels, and each pixel signal is processed. At that time, focus detection can be performed more accurately as the image signal composed of each pixel signal becomes larger, but if it is too large, the dynamic range over which the pixel signal can be processed is exceeded, resulting in the image signal being different from the actual one. On the contrary, the accuracy deteriorates.
[0006]
Therefore, it is common to use a storage type sensor and appropriately control the storage time.
[0007]
When there are a plurality of distance measuring points, the accumulation time of the area corresponding to each distance measuring point is controlled independently. Since the circuit scale for appropriately controlling the accumulation time is large and the circuit scale of the sensor including the control circuit when the number of distance measuring points is increased, the applicant of the present application has already applied Japanese Patent Application No. Hei 8-256288. Proposed a method in which the photoelectric conversion element is divided into regions for each distance measuring point, and the storage time is controlled by a single control unit while sequentially scanning each region.
[0008]
[Problems to be solved by the invention]
However, in this method, since the scanning operation is always performed during the accumulation time, it is conceivable that a lot of noise is generated and the accuracy is deteriorated or the current consumption is increased to waste energy.
[0009]
On the other hand, if the scanning operation is slow, the above problem can be solved. However, when focus detection is performed on a high-luminance target image, the image signal exceeds the dynamic range during the scanning operation for each region. 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-described problems, and an object of the present invention is to provide an inexpensive and accurate photoelectric conversion device and focus detection device.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the object, a photoelectric conversion device according to the present invention starts to accumulate a plurality of photoelectric conversion elements divided into a plurality of regions and photoelectric conversion elements in the plurality of regions. Accumulation starting means for causing plural Monitor means for sequentially monitoring and outputting the accumulation state of the photoelectric conversion elements in the region; Showing the accumulation state of photoelectric conversion elements in a plurality of regions, The monitor output that is output in order is a predetermined value and Respectively By comparing the determination means for determining whether or not to end the accumulation of photoelectric conversion elements in the region corresponding to the monitor output, and when the determination means determines that the accumulation should be ended, Accumulation termination means for terminating accumulation of photoelectric conversion elements in a region corresponding to the monitor output, the monitoring means, Within the plurality of areas repeatedly at a first timing until a predetermined time elapses after starting accumulation In order to monitor the storage status of After the predetermined time has elapsed after the start of accumulation, the accumulation states of the plurality of areas are repeatedly monitored and output in sequence at a second timing that is later than the first timing. It is characterized by that.
[0011]
The photoelectric conversion device according to the present invention is characterized in that a plurality of the photoelectric conversion elements are arranged in each of the plurality of regions.
[0012]
The photoelectric conversion device according to the present invention is characterized in that the plurality of photoelectric conversion elements constitute an area type sensor having a continuous two-dimensional spread.
[0013]
In the photoelectric conversion device according to the present invention, the monitor output is the maximum of the photoelectric conversion elements included in each region. of The signal is based on the amount of accumulated charge.
[0014]
In the photoelectric conversion device according to the present invention, the monitoring means provides the waiting time for the timing of the monitor output, First timing and second timing It is characterized by different.
[0015]
In the photoelectric conversion apparatus according to the present invention, the monitoring means changes the clock signal that controls the timing of the monitor output, thereby First timing and second timing It is characterized by different.
[0016]
Further, the focus detection apparatus according to the present invention includes a plurality of photoelectric conversion elements divided into a plurality of regions, an accumulation start unit for starting accumulation of photoelectric conversion elements in the plurality of regions, plural Monitor means for sequentially monitoring and outputting the accumulation state of the photoelectric conversion elements in the region; Showing the accumulation state of photoelectric conversion elements in a plurality of regions, The monitor output that is output in order is a predetermined value and Respectively By comparing the determination means for determining whether or not to end the accumulation of photoelectric conversion elements in the region corresponding to the monitor output, and when the determination means determines that the accumulation should be ended, Accumulation end means for ending accumulation of photoelectric conversion elements in the area corresponding to the monitor output, read-out means for reading out signals of each pixel which is each photoelectric conversion element in each of the divided areas, and read-out by the read-out means Detection means for performing focus detection of a subject by calculating a signal of each pixel that is output, and the monitoring means includes: Within the plurality of areas repeatedly at a first timing until a predetermined time elapses after starting accumulation In order to monitor the storage status of After the predetermined time has elapsed after the start of accumulation, the accumulation states of the plurality of areas are repeatedly monitored and output in sequence at a second timing that is later than the first timing. It is characterized by that.
[0017]
The focus detection apparatus according to the present invention is characterized in that a plurality of the photoelectric conversion elements are arranged in each of the plurality of regions.
[0018]
In the focus detection apparatus according to the present invention, the plurality of photoelectric conversion elements constitute an area type sensor having a continuous two-dimensional spread.
[0019]
In the focus detection apparatus according to the present invention, the monitor output is the maximum of the photoelectric conversion elements included in each region. of The signal is based on the amount of accumulated charge.
[0020]
Further, in the focus detection apparatus according to the present invention, the monitoring means provides a waiting time for the timing of the monitor output, thereby First timing and second timing It is characterized by different.
[0021]
In the focus detection apparatus according to the present invention, the monitor means changes the clock signal that controls the timing of the monitor output, thereby First timing and second timing It is characterized by different.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described. In describing the embodiment, the principle part of the focus detection device will be described with reference to FIGS.
[0023]
FIG. 7 is a cross-sectional view of a camera in which the focus detection device is incorporated.
[0024]
In the figure, 101 is an objective lens for condensing light from an object to be photographed, 102 is a semi-transparent main mirror that reflects incident light from 101, and 103 is disposed at the focal position of the objective lens 101. , 104 is a pentaprism that changes the direction of the light beam, 105 is an eyepiece for the photographer, 106 is a sub-mirror that operates during focus detection, 107 is a film such as a silver salt film, and 108 is a focus detection device. .
[0025]
In this figure, light from a subject not shown is transmitted through the objective lens 101 and then reflected upward by the main mirror 102 to form an image on the focusing screen 103. The image formed on the focusing screen 103 is visually recognized by the photographer or the observer through the eyepiece 105 after being reflected by the pentaprism 104 a plurality of times.
[0026]
On the other hand, a part of the light beam reaching the main mirror 102 from the objective lens 101 is transmitted through the main mirror 102, reflected downward by the sub mirror 106, and guided to the focus detection device 108.
[0027]
FIG. 8 is an exploded view showing only the objective lens 101 and the focus detection device 108 in FIG. 7 in order to explain the principle of focus detection.
[0028]
In the focus detection apparatus 108 of FIG. 8, 109 is a field mask arranged near the planned focal plane of the objective lens 101, that is, a plane conjugate with the film plane, 110 is a field lens arranged similarly near the planned focal plane, 111. Is a secondary imaging system composed of two lenses 111-1 and 111-2, and 112 is a pair of sensor arrays 112-1 and 112 arranged behind the two lenses 111-1 and 111-2. -2 includes a photoelectric conversion element 113, a diaphragm having two openings 113-1 and 113-2 arranged corresponding to the two lenses 111-1 and 111-2, and 114 a divided two regions The exit pupils of the objective lens 101 including 114-1 and 114-2 are shown.
[0029]
The field lens 110 has an effect of forming an image in the vicinity of the openings 113-1 and 113-2 of the stop 113 with respect to the regions 114-1 and 114-2 of the exit pupil 114 of the objective lens 101. The light beams 115-1 and 115-2 transmitted through the regions 114-1 and 114-2 of the exit pupil 114 form light quantity distributions in the two sensor rows 112-1 and 112-2, respectively. .
[0030]
The focus detection apparatus shown in FIG. 8 is generally called a phase difference detection method, and will be described using a graph of light quantity distribution formed in the sensor arrays 112-1 and 112-2 in FIG.
[0031]
In FIG. 9, 201 indicates the intensity of the light amount on the vertical axis of the graph. 202, the horizontal axis of the graph represents the spread of each pixel of the sensor rows 112-1, 112-2, and 207, 208 represent the light intensity output (hereinafter image signal) of the pixel. Reference numerals 203 and 204 denote the expansion of the sensor arrays 112-1 and 112-2, respectively, and are referred to as a first image and a second image for convenience. Reference numerals 205 and 206 denote central portions of the respective sensor rows.
[0032]
When the image formation point of the objective lens 101 coincides with the planned focal plane, the graph output is as shown in FIG. 9A, and the image outputs of the first image and the second image substantially coincide.
[0033]
On the other hand, when the imaging point of the objective lens 101 is on the front side of the planned focal plane, that is, on the side of the objective lens 101, on the two sensor rows 112-1 and 112-2 as shown in FIG. The light quantity distributions formed in the two are close to each other. On the other hand, when the imaging point of the objective lens 101 is on the rear side of the planned focal plane, the light quantity distributions formed on the two sensor rows 112-1 and 112-2, respectively, as shown in FIG. 9C. They are separated from each other.
[0034]
In addition, since the deviation amount of the light amount distribution formed on the two sensor rows 112-1 and 112-2 has a certain functional relationship with the defocus amount of the objective lens 101, that is, the focal point deviation amount, the deviation amount is determined by an appropriate calculation means. , The direction and amount of defocus of the objective lens 101 can be detected. The position of the lens system such as the objective lens 101 is moved in accordance with the direction and the amount, and the shift amount is set to be substantially zero, and the focus detection operation is completed.
[0035]
The image signal is generally subjected to analog-digital conversion (hereinafter referred to as AD conversion) from an analog output from a sensor, and then digitally processed by an arithmetic unit to perform the defocus amount calculation as described above. At this time, accumulation control to the sensor is performed with an appropriate accumulation time, and reading of the analog output is necessary to accurately calculate the defocus amount by reading with an appropriate amplification degree (hereinafter referred to as gain).
[0036]
FIG. 10 is a diagram for explaining in what state the image signal is accurate.
[0037]
In the figure, reference numeral 209 denotes the dynamic range of AD conversion. When the image signal is read out as shown in FIG. 10A, the defocus amount can be accurately calculated even if there is a little noise on the image signal because almost the entire AD conversion dynamic range is used. It is.
[0038]
On the other hand, in FIG. 10B, the image signal exceeds the dynamic range of AD conversion because the accumulation time is too long or the readout gain is too large. Accordingly, the portion of the image signal having a high light intensity is lost as information to be calculated, which causes an error in the defocus amount calculation. On the other hand, in FIG. 10C, the height of the image signal is very low because the accumulation time is too short or the readout gain is too small. This makes it impossible to ignore the influence of noise on the image signal, and this also causes an error in the defocus amount calculation.
[0039]
Therefore, appropriately controlling the accumulation time and the readout gain is an important issue in realizing an accurate focus detection apparatus.
[0040]
This is the end of the description of the principle part of the focus detection apparatus.
[0041]
In the photoelectric conversion device and the focus detection device using the photoelectric conversion device according to the embodiment of the present invention, a plurality of the focus detection devices described above are functionally present in one camera. For example, as shown in FIG. Even when there are 55 distance measuring points 302 in the screen 301 of the target image obtained when the photographer looks into the eyepiece 105, the focus detection can be performed on the same principle.
[0042]
FIG. 1 is an electric circuit block diagram of the focus detection apparatus 108.
[0043]
Reference numeral 1 denotes a controller that controls the accumulation of a plurality of sensor arrays and the reading of image signals. Reference numerals 2, 3, and 4 denote sensor row blocks of region 1, region 2, and region n (n is an integer equal to or larger than 2), and correspond to each distance measuring point 302 in FIG.
[0044]
In one sensor row block, a pair of sensor arrays constitutes a sensor unit because of the phase difference detection method, and the sensor array detects the first image with about 30 to 80 pixels and the second image with the same number of pixels. is doing. In addition, a peak detection circuit that detects an output value indicating the highest output during accumulation from the pixel, and a memory unit that temporarily stores the photoelectric conversion output accumulated in the sensor unit simultaneously with the end of accumulation Is arranged.
[0045]
The peak detection circuit outputs the highest output value (p-out) in the pixel to one input unit of the comparator 5 when the analog switch 12 is ON. 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 greater than VR, i.e., the accumulation should be terminated.
[0046]
When the analog switch 11 is turned on from the memory unit, the output of each pixel is sequentially output to the input of the buffer amplifier 6 by the shift signal from the controller 1. The buffer amplifier 6 outputs a pixel signal from Vout with an appropriate gain.
[0047]
When the controller 1 outputs the rst signal (reset signal), the charges of the sensor units in all the areas 1 to n are cleared, and accumulation control of all the areas starts from here. The controller 1 sequentially outputs psel-1 and psel-2, and after outputting psel-n to the nth area, which is the last area, returns to psel-1. By outputting this psel-m (m is 1 to n), the analog switch 12 is turned on, so that a peak signal (p-out) can be obtained in order from each region 1 to n. Based on the comp signal, by determining whether or not the peak signal (p-out) from the selected area exceeds a predetermined level, accumulation control is performed to determine whether to continue or stop accumulation in that area. I can do it.
[0048]
If the comp signal is 1, the trans-m signal is output to stop the accumulation of the sensor in the area, 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 transfer operation is not performed and the sensor accumulation is continued. Also, if the area has been transferred once, it is naturally not transferred again.
[0049]
The area transferred to the memory unit can be selected by the sel-m signal, and the image output can be read by the shift signal.
[0050]
(First embodiment)
In FIG. 2, the first embodiment of the controller 1 in FIG. 1 will be described in more detail.
[0051]
Reference numeral 20 denotes a microcomputer (μCOM) that controls the entire electric circuit of the focus detection device 108 (see FIG. 8). Reference numeral 21 denotes a clock generator that outputs a clock signal (clk) having a constant period. Reference numeral 22 denotes a counter. When a reset signal (RST) is received from the microcomputer 20, the counter value is cleared to zero, and then the clk signal from the clock generator 21 is counted up, and the count value ( cnt-value).
[0052]
An accumulation time memory 23 stores the accumulation time of each area. When a reset signal (RST) is received from the microcomputer 20, all the memories are cleared to zero. When a trans-m signal corresponding to each area comes from the microcomputer 20, the cnt-value at that time is stored in reg-m. In this way, the accumulation times of all the areas can be stored individually. The accumulated time stored here is used for correcting the noise amount of the image signal, etc., but is not directly related to the present invention, so a detailed description is omitted.
[0053]
Reference numeral 24 denotes a comp signal input terminal from the comparator 5 in FIG. 1. As described above, the microcomputer 20 determines whether the comp-m signal is output when the comp signal is 0 or 1. .
[0054]
Reference numeral 25 denotes the output of the rst signal to each region in FIG. 1, and also clears the charge of the sensor unit in FIG. 1 along with clearing the counter 22 and the accumulation time memory 23 in FIG.
[0055]
Reference numerals 26, 28, and 30 denote output terminals of the trans-m signal output from the microcomputer 20 to the sensor unit of FIG. 1, and from the sensor unit in FIG. 1 to the memory unit together with the control of the accumulation time memory in FIG. Controls the transfer of photoelectrically converted charges.
[0056]
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. 1, and control which region of the output value in FIG.
[0057]
The operation of the microcomputer 20 will be described in detail with reference to the flowchart of FIG.
[0058]
When the operation starts in step S100, an rst signal is output (step S101), the counter 22 and the accumulation time memory 23 are cleared, and the charges of the sensor portions in each region are cleared to start accumulation. Then, 0 is input to the register sel inside the μCOM 20. The register sel has a meaning as to which area is selected for image output reading.
[0059]
Next, the register w-cnt in the μCOM 20 is cleared to 0 (step S102). The register w-cnt has a meaning of making a wait time by counting up later and comparing with a predetermined level.
[0060]
Next, the clk signal is input, and it is determined whether or not the clk signal has risen from 0 to 1 (step S103). If it has risen, the process proceeds to step S104. If not, the process stops at step S103.
[0061]
Next, the count value (cnt-value) of the counter 22 is input (step S104).
[0062]
If the count value is smaller than the predetermined level c1 in step S105, the process proceeds to step S106 and subsequent steps.
[0063]
Next, the register w-cnt is cleared to 0 (step S106).
[0064]
In step S107, the register sel is incremented by one (incremented). This operation corresponds to a part in which accumulation control is performed in order for each region.
[0065]
Next, when the register sel is larger than n, that is, when the number of distance measurement points exceeds the range, 1 is input to the register sel and the process returns to the area 1 again (steps S108 and S109).
[0066]
If the register sel is n or less in step S108, the psel-m signal is output (step S110). As a result, the accumulation state of the region m, that is, the peak value of the photoelectric conversion amount of the pixels in the region m appears in the p-out output.
[0067]
In step S111, if it is determined that the area m is sufficiently accumulated, the comparator 5 outputs a comp signal of 1. Therefore, the microcomputer 20 outputs a trans-m signal, and each of the sensor units in the area m is output. The charge of the pixel is transferred to the memory unit to finish the accumulation (step S112), and the process returns to step S102. When the degree of accumulation is still insufficient, 0 is output as the comp signal, and the process directly returns to step S102.
[0068]
On the other hand, if the count value (cnt-value) is greater than or equal to c1 in step S105, the process proceeds to step S113, and 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 to perform the operation as described above.
[0069]
If the register w-cnt is not c2 in step S113, the register w-cnt is incremented by 1 (incremented) in step S114, and the process returns to step S103 to wait for the next rising edge of the clk signal.
[0070]
As described above, in the first embodiment, since cnt-value has been low for a while after the start of sensor accumulation, the process immediately proceeds from step S105 to step S106, and the accumulation amount for each region from region 1 to region n is determined. Are performed in synchronization with the rise of the clk signal without resting in turn. Then, when cnt-value exceeds a predetermined value c1 after some time has elapsed since the start of sensor accumulation, if the register w-cnt is not counted up to the predetermined value c2, it is not possible to determine the accumulated amount for each region. The drive frequency for judging the accumulated amount of the sensor is lowered.
[0071]
As a result, the focus detection operation of a high-luminance target image can be accurately performed because the image signal can be formed without exceeding the dynamic range, and the overall drive frequency is reduced, so that noise can be reduced extremely and consumption is also reduced. The current can also be greatly reduced. Thus, according to the present embodiment, it is possible to realize a photoelectric conversion device that is easy to use because it has high accuracy, is inexpensive, and has many distance measuring points, and a focus detection device using the photoelectric conversion device.
[0072]
(Second embodiment)
In the second embodiment, only the flowchart of FIG. 3 is replaced with FIG. 4 with respect to the first embodiment.
[0073]
The operation of the second embodiment will be described with reference to FIG.
[0074]
First, steps S200 to S203 are the same as steps S100 to S103.
[0075]
In step S204, the register sel is incremented by one (incremented) as in step S107.
[0076]
When the register sel is n or smaller than n, the process proceeds to step S210 and after. When the register sel exceeds n, the process proceeds to step S206.
[0077]
In step S206, the count value (cnt-value) of the counter 22 is input.
[0078]
In step S207, if the count value is smaller than the predetermined level c1, the process proceeds to step S208, and if it is the same or larger, the process proceeds to step S213 and the subsequent steps.
[0079]
In step S208, the register w-cnt is cleared to zero.
[0080]
In step S209, 1 is input to the register sel, and the region 1 is returned again.
[0081]
Steps S210 to S212 are the same as steps S110 to S112.
[0082]
If the count value is greater than or equal to c1 in step S207, it is determined whether or not 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.
[0083]
If the register w-cnt is not c2 in step S213, the register w-cnt is incremented by 1 (incremented) in step S214, and the process returns to step S203 to wait for the rise of the next clk signal.
[0084]
As described above, in the second embodiment, since the accumulation of the sensor is started, the cnt-value is small for a while, so that the process proceeds to step S208 after step S207. The determination of the amount of accumulation in each region from 1 to region n is performed in synchronization with the rise of the clk signal without resting. When cnt-value exceeds a predetermined value c1 after a while after the sensor accumulation starts, the region 1 to the region n are synchronized with the rise of the clk signal without resting the judgment of the accumulation amount of each region. However, after the determination of the accumulation amount of the last region n is completed, a wait operation is performed until the register w-cnt is counted up to the predetermined value c2. Again, this reduces the drive frequency for determining the accumulated amount.
[0085]
Also in the second embodiment, an effect almost the same as that of the first embodiment can be obtained, and a photoelectric conversion device that is easy to use because it has high accuracy, is inexpensive, and has many distance measuring points, and a focus detection device using the photoelectric conversion device can be realized.
[0086]
(Third embodiment)
Compared to the first and second embodiments, the third embodiment changes the detailed view of the controller 1 in FIG. 2 as shown in FIG. 5, and the flowcharts in FIGS. 3 and 4 change as shown in FIG. ing.
[0087]
The different parts will be described with reference to FIG. 5. Reference numeral 32 denotes a divider, which divides the clk signal from the clock generator 21 and outputs a d-out signal.
[0088]
Reference numeral 33 denotes a selector which selects either the clk signal from the clock generator 21 or the d-out signal from the division period 32 by the output c-sel signal of the microcomputer 20 and outputs the c-clk signal. When c-sel is 0, the clk signal is selected. When c-sel is 1, the d-out signal is selected.
[0089]
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 in FIG.
[0090]
Next, the operation of the third embodiment will be described with reference to the flowchart of FIG.
[0091]
Steps S300 to S301 are the same as steps S100 to S101.
[0092]
In step S302, the count value (cnt-value) of the counter 22 is input.
[0093]
In step S303 to step S305, if the count value is smaller than the predetermined level c1, the c-sel output is set to 0. If the count value is equal to or greater than c1, the c-sel output is 1.
[0094]
In step S306, the clk signal is input, and it is determined whether or not the clk signal has risen from 0 to 1. If so, the process proceeds to step S307. If not, the process stops at step S306.
[0095]
Steps S307 to S312 are the same as steps S107 to S112.
[0096]
As described above, in the third embodiment, since cnt-value is low for a while after the sensor accumulation is started, c-sel becomes 0 and the clk signal is selected as the output c-clk signal from the selector 33. Then, since the clk signal is input to both the microcomputer 20 and the counter 22, sequential region selection for accumulation determination is driven by a signal from the clock generator 21 and driven at a fast cycle.
[0097]
On the other hand, when cnt-value exceeds the predetermined value c1 after a while after the accumulation starts, c-sel becomes 1, and the output c-clk signal from the selector 33 is selected as the d-out signal. For this reason, the driving frequency of the accumulation control becomes slow. At the same time, the counter of the accumulation time counts up quickly for a while after the accumulation starts, but the count-up is delayed after a while.
[0098]
In the third embodiment, substantially the same effects as those in the first and second embodiments are obtained, and the flowchart is simplified and the software load is reduced.
[0099]
Note that the present invention can be applied to modifications or variations of the above-described embodiment without departing from the spirit of the present invention.
[0100]
For example, in the above example, the description is limited to the camera, but the present invention is of course not limited thereto, and can be applied to other devices having a focus detection function. Further, although the drive frequency for determining the storage amount is changed at a certain point where the storage time has elapsed, it is of course possible to change it continuously and gradually. Further, the description is limited to the phase difference detection method, but the present invention is not limited to this as long as the image signal is extracted and processed.
[0101]
The plurality of photoelectric conversion elements indicate sensor units in the sensor array blocks 2, 3, and 4 in FIG. 1, and the plurality of areas are the areas of the sensor array blocks 2, 3, 4, and the like in FIG. That is, the distance measuring point 302 described with reference to FIG. The accumulation control means includes the controller 1 in FIG. 1 and the psel-m signal, trans-m signal, and the like that drive the sensor array blocks 2, 3, and 4. In FIG. Has been.
[0102]
The accumulation start means is the rst signal in FIG. 1 or the operation in step S101 in FIG.
[0103]
The monitoring means is the p-out signal in FIG. 1, and the determining means is described in the comp output of the comparator 5 in FIG. 1, step S111 in FIG.
[0104]
The accumulation end means is the trans-m signal in FIG. 1 and step S112 in FIG.
[0105]
The fact that the predetermined time interval is different between immediately after the start of storage and after a while after the start of storage is described in the flowchart of FIG.
[0106]
【The invention's effect】
As described above, according to the present invention, since the drive frequency of the accumulation control is changed after a while from the start of accumulation, the focus detection operation of the high-luminance target image also causes the image signal to exceed the dynamic range. Since it can be formed without any problem, it can be made with high accuracy, and the overall drive frequency is lowered, so that noise can be reduced drastically and current consumption can be greatly reduced. A photoelectric conversion device and a focus detection device using the photoelectric conversion device can be realized.
[0107]
[Brief description of the drawings]
FIG. 1 is an electric circuit block diagram of a focus detection apparatus.
FIG. 2 is a diagram illustrating 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 illustrating 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 apparatus;
FIG. 8 is a diagram for explaining the principle of the focus detection apparatus;
FIG. 9 is a diagram showing a light amount 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 ranging points within a screen.
[Explanation of symbols]
1 Controller
2,3,4 sensor block block
20 Microcomputer
21 Clock generator
22 counter

Claims (12)

A plurality of photoelectric conversion elements divided into a plurality of regions;
Accumulation starting means for starting accumulation of photoelectric conversion elements in the plurality of regions;
Monitoring means for sequentially monitoring and outputting the accumulation state of the photoelectric conversion elements in the plurality of regions;
Completing the accumulation of photoelectric conversion elements in the region corresponding to the monitor output by comparing the monitor output sequentially output indicating the accumulation state of the photoelectric conversion elements in the plurality of regions with a predetermined value, respectively. A determination means for determining whether or not to be performed;
Accumulation determining means for ending accumulation of photoelectric conversion elements in a region corresponding to the monitor output when it is determined by the determination means that accumulation should be terminated,
The monitoring means repeatedly outputs the accumulated state in the plurality of areas in order at a first timing until a predetermined time elapses after the accumulation starts, and after the predetermined time elapses after the accumulation starts. the photoelectric conversion device according to claim Rukoto causes the monitor output sequentially storage state of the plurality of regions repeated at a second timing later than the first timing.   The photoelectric conversion device according to claim 1, wherein a plurality of the photoelectric conversion elements are arranged in each of the plurality of regions.   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.   The photoelectric conversion apparatus 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 region. The photoelectric conversion apparatus according to claim 1, wherein the monitoring unit makes the first timing different from the second timing by providing a waiting time for the timing of the monitor output. 2. The photoelectric conversion apparatus according to claim 1, wherein the monitor unit changes the first timing and the second timing by changing a clock signal for controlling the timing of the monitor output. A plurality of photoelectric conversion elements divided into a plurality of regions;
Accumulation starting means for starting accumulation of photoelectric conversion elements in the plurality of regions;
Monitoring means for sequentially monitoring and outputting the accumulation state of the photoelectric conversion elements in the plurality of regions;
Completing the accumulation of photoelectric conversion elements in the region corresponding to the monitor output by comparing the monitor output sequentially output indicating the accumulation state of the photoelectric conversion elements in the plurality of regions with a predetermined value, respectively. A determination means for determining whether or not to be performed;
Accumulation determining means for ending accumulation of photoelectric conversion elements in a region corresponding to the monitor output when it is determined by the determination means that accumulation should be terminated;
Reading means for reading out the signal of each pixel which is each photoelectric conversion element in each of the divided areas;
Detecting means for performing focus detection of a subject by calculating a signal of each pixel read by the reading means;
The monitoring means repeatedly outputs the accumulated state in the plurality of areas in order at a first timing until a predetermined time elapses after the accumulation starts, and after the predetermined time elapses after the accumulation starts. focus detecting apparatus according to claim Rukoto sequentially to monitor output storage state of the plurality of regions repeated at a slower second timing than the first timing.   The focus detection apparatus according to claim 7, wherein a plurality of the photoelectric conversion elements are arranged in each of the plurality of regions.   The focus detection apparatus according to claim 7, wherein the plurality of photoelectric conversion elements constitute an area-type sensor having a continuous two-dimensional extent.   The focus detection apparatus according to claim 7, wherein the monitor output is a signal based on a maximum accumulated charge amount among photoelectric conversion elements included in each region. The focus detection apparatus according to claim 7, wherein the monitoring unit makes the first timing different from the second timing by providing a waiting time for the timing of the monitor output. The focus detection apparatus according to claim 7, wherein the monitoring unit changes the first timing and the second timing by changing a clock signal that controls the timing of the monitor output.

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