JP2006039396A - Photoelectric conversion system, focal point detecting device, focal point detecting method, and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion system, a focal point detecting device, a focal point detecting method, and an imaging apparatus, which perform a correlation operation, by extracting only an effective contrast component in a subject with low luminance or a subject with a small contrast difference, thereby focusing operation comparatively correctly. <P>SOLUTION: The focal point detecting device 120 is provided. When the minimum accumulation level in the division block of a focal point detection area is not near a focal point detection area, the focal point detecting device externally supplies a voltage level equal to the minimum accumulation level in the focal point detection area, thereby subtracting the external voltage level from the accumulation level of each pixel and extracting only a contrast component. Alternatively, for each block, the focal point detecting device selects subtracting the minimum accumulation level of the division block or subtracting the minimum accumulation level supplied externally, thereby allowing arbitrary setting. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photoelectric conversion device, a focus detection device, a focus detection method, and an imaging device that are used in optical equipment such as a photographic camera and a video camera.

  In general, an imaging apparatus such as a digital single-lens reflex camera has an autofocus (AF) function, and an automatic focus detection apparatus (focus detection apparatus) is mounted in order to realize the AF function.

FIG. 1 is a simplified diagram of an electronic camera as an imaging apparatus equipped with a phase difference type focus detection apparatus.
This electronic camera has a single-lens reflex configuration having a quick return mirror 11 composed of a half mirror, and subject image light incident from the photographing lens 12 is reflected by the quick return mirror 11 and guided to the viewfinder 13.
Further, the subject image light transmitted through the quick return mirror 11 is reflected by the sub mirror 14 and guided to the focus detection device 15.

The quick return mirror 11 moves out of the photographing optical path according to the shutter release.
Accordingly, the subject image light incident from the photographing lens 12 is received by the photoelectric conversion element (for example, CCD) 16. Thus, the image signal photoelectrically converted by the photoelectric conversion element 16 is signal-processed and stored in the memory. .

FIG. 2 is an optical system diagram showing a configuration example of the focus detection device 15 described above.
The focus detection device 15 includes a field mask 17, a condenser lens 18, an aperture mask 19, re-imaging lenses 20 and 21, and a focus detection sensor 22 as a focus detection sensor as a basic configuration.

In the focus detection device 15, the light beams 23 a and 23 b that have passed through a specific exit surface of the photographing lens 12 form an image on the light receiving surface of the focus detection sensor 22 as a pair of subject image light as illustrated.
The interval between the two images at the time of focusing is an image interval determined by the device design. When the defocus is the front pin, the image interval is widened, and when it is the rear pin, the image interval is narrowed.

  Therefore, based on the output signal of the focus detection sensor 22, the amount of defocus and the direction of shift are calculated from the difference between the image interval at the time of focusing and the image interval at the time of defocus, and the photographing lens 12 is moved according to this calculated signal. It can be driven to obtain a focused state.

  On the other hand, as the focus detection sensor 22 used in the above-described focus detection apparatus, as shown in FIG. 3, the line sensor 24 in which the photodiodes 24a are arranged in one row, or as shown in FIG. There is an area sensor 25 in which photodiodes 25a are two-dimensionally arranged.

In the line sensor 24 and the area sensor 25 described above, each pixel (light receiving surface of each photodiode) is formed in a rectangular shape in order to increase effective sensitivity.
This is because if the light-receiving surface of each photodiode is square, the pixel pitch becomes wide in order to obtain sufficient effective sensitivity, which is not preferable for improving focus detection accuracy.
Therefore, in order to increase the pixel area (pixel area) by reducing the pixel pitch as much as possible, the pixel is formed as a rectangular pixel.

On the other hand, when the pixel is rectangular, the following problem occurs.
That is, as shown in FIGS. 5A and 5B, when the oblique subject 26 forms an image on the light receiving surface, a so-called “edge droop” occurs at the edge of the sensor output signal.
As shown in FIGS. 6A and 6B, the edge of the sensor output signal becomes larger as the rectangular pixel 24a (25a) becomes longer.

Therefore, in the sensors 24 and 25 as described above, the longer the rectangular pixel 24a (25a), the larger the pixel area and the shorter the charge accumulation time for improving the effective sensitivity. This increases the edge of the sensor output value.
In addition, as the rectangular pixel 24a (25a) is shortened, the edge of the sensor output signal is reduced. On the other hand, the charge accumulation time is increased due to the decrease in effective sensitivity.

  In addition, when the vertical subject 26 that is parallel to the rectangular pixel 24a (25a) forms an image, as shown in FIGS. 7A, 7B, 8A, and 8B, Regardless of the length of the rectangular pixel 24a (25a), the sensor output signal has extremely little edge droop.

As described above, various types of photoelectric conversion elements as sensors have already been proposed in order that rectangular pixels exhibit characteristics of long and short.
In particular, as a photoelectric conversion element formed as an area sensor, an electronic camera that performs AF control by a hill-climbing method in addition to an individual imaging element that can add and read arbitrary two lines in addition to reading for each line In the focus detection sensor having a mode for reading each line independently and a mode for reading by adding two or more lines, or if the luminance is sufficient according to the luminance of the subject, the pixel is not added and the luminance is When it is relatively low, there is a CCD image pickup device that adds pixels adjacent in the vertical direction.

  However, the image sensor and sensor as described above have not solved the edge of the output signal due to the image formation of the oblique subject, and the relationship between the pixel area and the charge accumulation time is not taken into consideration. When used as a detection sensor, it was not sufficient to obtain high detection accuracy.

The above-described defocus amount is calculated using digital data obtained by A / D converting the output of the photoelectric conversion element by the CPU, but has an automatic focus detection function capable of covering a wide range with high accuracy and high speed. In order to achieve this, an improvement in sensitivity / S / N ratio is desired. For this purpose, it is necessary to extract an output signal (sensor data) with high accuracy and high speed from the photoelectric conversion element for focus detection.
The photoelectric conversion device used in the phase difference type focus detection device does not require a DC component of sensor data, and it is desirable to extract only the AC component, that is, the sensor data corresponding to the contrast component of the subject.
From this point of view, the applicant of the present invention describes the invention described in the following patent document regarding the accumulation control of the image sensor, the output device, etc. for obtaining the sensor signal with higher accuracy by the detection signals of the maximum value and the minimum value incident on the sensor. Is disclosed.

  That is, in Patent Document 1, the present applicant electrically detects the strongest partial light and electrically detects the weakest partial light among light incident on an image sensor such as a CCD imaging device. A technique relating to an output device of an image sensor that monitors the brightness of light by a differential amplifier circuit in which the amplification degree is set according to the difference is proposed.

  In Patent Document 2, the applicant of the present invention electrically detects the strongest partial light and the weakest partial light among the light incident on an image sensor such as a CCD image sensor, and the difference between these is detected. A technique related to a charge accumulation time control device for an image sensor that restricts the charge accumulation time of the image sensor according to the time until a predetermined level is reached is proposed.

  In Patent Document 3, the present applicant obtains photometric data from a two-dimensional sensor having a wide ranging area, thereby reducing the space for the photometric sensor without providing a separate photometric sensor, and focusing detection and subject luminance. A technique related to an automatic focus detection apparatus using a two-dimensional sensor that enables the best control for focus detection and photometry by controlling the data acquisition operation according to the situation has been proposed.

  In addition to the above-mentioned patent documents, the following technologies are known as technologies related to the accumulation control of area sensors (photoelectric conversion elements) and the arrangement of light receiving units.

  A block is set at an arbitrary position of a pair of area sensors, and a maximum exposure amount detecting means and a minimum exposure amount detecting means are arranged for each block of both area sensors, and the maximum exposure amount detecting means and the minimum exposure amount of each block are arranged. As a technique for controlling the exposure amount for each block by the detection means, for example, the accumulated charge amount in each pixel block from the start of the accumulation operation is monitored, and the accumulation control and the output of the pixel signal are independent for each pixel block. For example, a technique related to the area sensor to be executed, a technique for detecting that the accumulation level reaches a predetermined level for each divided region, and starting reading of each pixel based on the detection result are known.

  Further, as a technique for disposing a maximum exposure amount detecting unit on one of a pair of area sensors and a minimum exposure amount detecting unit on the other side, for example, an element row for detecting a maximum value signal of a photoelectric conversion element and a minimum value signal are detected. The device array is divided and arranged as a pair of photoelectric conversion device arrays, or each unit is alternately arranged with the continuously arranged photoelectric conversion devices as one unit, so that the chip yield and the photoelectric conversion are arranged. A technique for improving the degree of freedom of arrangement of the light receiving portions of the element is known.

In the phase difference type focus detection device, the image of the subject is received by the sensor, and focus detection is performed to obtain the phase difference from the contrast difference of the pixel output. However, since only the contrast component in the focus detection area is extracted, There has been proposed a method of removing unnecessary components by subtracting the minimum accumulation level of the detection region from the accumulation level of the pixels. Conventionally, in the case of using a linear sensor, the focus detection area is fixed, and the minimum accumulation level of the pixels is within the detection area. Since the phase difference is detected by using it, many portions other than the detection region are included, and when the accumulation level exists outside the detection region, only the contrast component can be extracted.
JP-A 64-85480 Japanese Patent Laid-Open No. 1-103077 JP-A-10-161014

By the way, the technologies disclosed in Patent Documents 1 and 2 are technologies relating to image sensors, particularly line sensors, and in order to apply them to automatic focus detection of an imaging apparatus, the technologies described in these Patent Literatures are It needs to be applied to sensors. In other words, since the line sensor can only perform focus detection in a limited area in the vertical and horizontal directions of the subject image, it is necessary to use the area sensor to perform high-precision focus detection in a wider range. There is.
Further, the technique disclosed in Patent Document 3 does not mention that the area sensor is divided into blocks for each block, and independent accumulation control is performed for each block, and more accurate focus detection is possible. There is room.

Further, the above-described technique, that is, the maximum exposure amount detection means and the minimum exposure amount detection means are arranged for each block of both area sensors, and each block is detected by the maximum exposure amount detection means and the minimum exposure amount detection means of each block. Although the technique for controlling the exposure amount and the technique for disposing the maximum exposure amount detection means on one of the pair of area sensors and the minimum exposure amount detection means on the other side are known techniques, the maximum exposure amount detection is performed in this way. If either of the means or the minimum exposure detection means is arranged in both area sensors, there is a mounting problem that the detection signal must be taken out from each area sensor and the circuit scale including the wiring becomes large. Of the pair of area sensors, it is desirable to arrange the maximum exposure amount detection means and the minimum exposure amount detection means only in one area sensor.
Further, if the maximum exposure amount detection means and the minimum exposure amount detection means are arranged only in one area sensor, the other area sensor can be accumulated while the one area sensor is monitored, and the entire process is performed. Time reduction can be expected.

  Also, an area sensor is used, and the area sensor is divided into a plurality of blocks for each focus detection point, focus detection is performed using a part of the divided blocks, and a minimum accumulation level is set for each divided area. In the focus detection device to detect, when the minimum accumulation level is in the vicinity of the focus detection area of the block, the contrast component can be extracted by subtracting the minimum accumulation level from the accumulation level of each pixel. However, when the minimum accumulation level is not in the vicinity of the focus detection area, it is impossible to extract only the contrast component of the block. For this reason, it is not possible to extract only the contrast component from a low-luminance subject or a subject with a small contrast difference.

  The first object of the present invention is to enable high-speed and high-precision automatic focus detection over a wide area, and to save space, and for only a low-brightness object or a low-contrast object with only a contrast component. Therefore, it is possible to provide a photoelectric conversion device, a focus detection device and method, and an imaging device that can improve the focusing accuracy and can detect a focus even on a low-luminance subject.

  The second object of the present invention is to maintain the drooping characteristics of the edge of the sensor output signal due to the image formation of the oblique subject, to make the effective sensitivity appropriate, to improve the focus detection accuracy as much as possible, and to reduce the luminance. Photoelectric conversion device, focus detection device, and method capable of extracting only the contrast component of a subject having a small contrast difference and improving the focusing accuracy and detecting the focus even on a low-luminance subject And providing an imaging apparatus.

  In order to achieve the above object, a photoelectric conversion apparatus according to a first aspect of the present invention includes an area sensor in which a light receiving unit is two-dimensionally arranged, a dividing unit that divides the area sensor into a plurality of blocks, and the dividing unit. A maximum value detecting means for detecting the maximum exposure value of each block divided by the above, a minimum value detecting means for detecting the minimum exposure value of each block divided by the dividing means, and an external device for inputting an external minimum value from the outside Minimum value input means, selection means for selectively outputting the exposure minimum value output from the minimum value detection means and the external minimum value input from the external minimum value input means, and output from the maximum value detection means Monitor output means for generating a monitor signal from the exposure maximum value and the exposure minimum value or external minimum value output from the selection means.

  Preferably, the apparatus further comprises block selecting means for designating at least one of the plurality of blocks divided by the dividing means, and the monitor output means sequentially outputs the monitor signal of each block for each block at a common output terminal. When a block is selected by the block selection means, the monitor signal of the selected block is output to a common output terminal as needed.

  Preferably, the monitor output means outputs a monitor signal in order of each block read from the area sensor when no block is designated by the block selection means, and the block selection means outputs a specific block. Is selected, the monitor signal of a specific block is output to the common output terminal by interrupting in block order.

  Preferably, the area sensor is a sensor having a pair of areas, and the maximum value detecting means, the minimum value detecting means, and the monitor output means are arranged in only one of the pair of area sensors.

  Preferably, there is provided means for controlling the exposure amounts of both the pair of area sensors by a monitor signal from the monitor output means.

  A focus detection apparatus according to a second aspect of the present invention includes an area sensor in which a light receiving unit is two-dimensionally arranged, a dividing unit that divides the area sensor into a plurality of blocks, and a block that is divided by the dividing unit. Maximum value detection means for detecting the exposure maximum value, minimum value detection means for detecting the exposure minimum value of each block divided by the dividing means, external minimum value input means for inputting the external minimum value from the outside, and the above Selection means for selectively outputting the minimum exposure value output from the minimum value detection means and the external minimum value input from the external minimum value input means; the maximum exposure value output from the maximum value detection means and the selection The monitor output means for generating a monitor signal from the exposure minimum value or the external minimum value output from the means, and the exposure amount of all the blocks is accumulated to a predetermined value or more by the monitor signal. An exposure amount detecting means for detecting the above, an instruction means for instructing reading of the accumulated data of the area sensor when it is detected by the exposure amount detection means that all the blocks have been accumulated more than a predetermined value, and the instruction means The storage data output means for outputting the storage data of the area sensor based on the instruction, and the phase difference signal generation means for generating a phase difference signal from the storage data output by the storage data output means.

  An imaging apparatus according to a third aspect of the present invention includes an Eli sensor in which a light receiving unit is two-dimensionally arranged, a dividing unit that divides the area sensor into a plurality of blocks, and a maximum exposure of each block divided by the dividing unit. A maximum value detecting means for detecting a value, a minimum value detecting means for detecting an exposure minimum value of each block divided by the dividing means, an external minimum value inputting means for inputting an external minimum value from the outside, and the minimum value From the selection means for selectively outputting the exposure minimum value output from the detection means and the external minimum value input from the external minimum value input means, the exposure maximum value output from the maximum value detection means, and the selection means Monitor output means for generating a monitor signal from the output minimum exposure value or external minimum value, and the exposure amount for each of the blocks accumulated by the monitor signal above a predetermined value An exposure amount detection means for detecting, an instruction means for instructing reading of accumulated data of the area sensor when it is detected by the exposure amount detection means that all blocks have been accumulated at a predetermined value or more, and an instruction by the instruction means Based on the accumulated data output means for outputting the accumulated data of the area sensor, the phase difference signal generating means for generating a phase difference signal from the accumulated data output by the accumulated data output means, and the phase difference signal generating means. A focus control unit that performs focus control using a phase difference signal, and an optical lens that is controlled by the focus control unit.

  A focus detection method according to a fourth aspect of the present invention includes a division step of dividing an area sensor having a light receiving portion arranged two-dimensionally into a plurality of blocks, and a maximum value for detecting an exposure maximum value of each of the divided blocks. A detection step; a minimum value detection step for detecting an exposure minimum value of each of the divided blocks; an external minimum value input step for inputting an external minimum value from outside; and the detected exposure minimum value and the external input to be input A selection step for selectively outputting a minimum value; a monitor output step for generating a monitor signal from the detected maximum exposure value and the selected minimum exposure value or external minimum value; and An exposure amount detection step for detecting that the exposure amount is accumulated above a predetermined value, and all the blocks are accumulated at a predetermined value or more by the exposure amount detection step. Instructing the readout of the accumulated data of the area sensor when detecting the above, an accumulated data output step of outputting the accumulated data of the area sensor based on the instruction, and a phase difference signal from the output accumulated data Generating a phase difference signal.

According to the present invention, since the area sensor is used, focus detection can be performed on a wider area.
According to the present invention, the area sensor is divided into a plurality of blocks, and the function of monitoring the difference between the maximum value and the minimum value of the accumulated signal of each block is provided, so according to the brightness and contrast for each block. Accumulation control is possible, so that highly accurate focus detection can be performed.
According to the present invention, since the maximum exposure amount detection means and the minimum exposure amount detection means are arranged only in one area sensor, the peripheral circuit including the wiring becomes compact, and the one area sensor is monitored. While the other area sensor is being accumulated, the entire processing time is reduced, and high-speed focus detection is possible.
According to the present invention, the maximum exposure amount detection means and the minimum exposure amount detection means are arranged for each block and share the monitor output for each block, so that variation in output circuit characteristics between the blocks can be reduced, and The apparatus can be downsized.

  Furthermore, according to the present invention, in a subject under low luminance or a subject with a small contrast difference, only effective contrast components can be extracted and correlation calculation can be performed, and a more accurate focusing operation can be performed. Autofocus corresponding to the shooting environment is possible.

Further, according to the present invention, a photodiode line with a narrow pixel area or a photodiode line with a wide pixel area is read, and further, a photodiode line with a narrow pixel area and a photodiode line with a wide pixel area are added and read. be able to.
As a result, it is possible to obtain a highly accurate sensor output signal in which effective sensitivity is properly maintained and focus detection does not vary.

In addition, it is possible to obtain a focus detection signal having an effective sensitivity corresponding to a high S / N ratio with a pixel area area that matches the brightness of the subject.
In addition, an imaging device having a highly accurate focus function can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 9 is a diagram schematically showing an electronic camera as an imaging apparatus employing the automatic focus detection apparatus according to the present invention.

As shown in FIG. 9, the electronic camera 100 according to the present embodiment includes an optical system 110, a focus detection device 120, and a controller 130.
The focus detection device 12 includes the photoelectric conversion device according to the present invention.

  As shown in FIG. 1, the optical system 110 includes an imaging lens 111, a quick turn mirror 112, a focusing screen 113, a pentaprism 114, a sub mirror 115, and a reflection mirror 116. In FIG. 9, reference numeral 117 denotes a film surface.

In this optical system 110, the image of the subject passes through the imaging lens 111 and is guided to the quick turn mirror 112 and forms an image on the upper focusing screen 113.
On the other hand, the image of the subject that has passed through the quick turn mirror 112 is reflected by the sub mirror 115 and the reflection mirror 116, guided to the focus detection device 120, and received by a sensor in the focus detection device 120.

  As illustrated in FIG. 9, the focus detection device 120 includes a reflection mirror 121, a re-imaging lens 122, and a focus detection sensor 123.

FIG. 10 is a diagram schematically illustrating an image formation state by the re-imaging lens 122 and the focus detection sensor 123 in the focus detection device 120.
As shown in FIG. 10, the light beam reflected from the subject in the focus detection device 120 is squeezed by the diaphragm 124 and guided to the re-imaging lens 122. The light flux that has passed through the re-imaging lens 122 forms an image of the subject on, for example, four sensor surfaces A, A ′, B, and B ′.
As described above, the focus detection device 120 includes a plurality of regions for detecting the phase difference.

FIG. 11 is a diagram for explaining the principle of detecting the phase difference.
12A to 12C are diagrams showing the light quantity distribution of the subject image received by the A and A ′ planes of FIG.

As shown in FIG. 11, the subject image passes through 111-1 and 111-2 of the imaging level (objective lens) 111, passes through the reflection mirror 116 at the positions 116-1 and 116-2, and is guided to the focus detection device 120. It is burned. The subject image guided to the focus detection device 120 is guided to the re-imaging lens 122 and reflected on the sensor surfaces A and A ′.
The subject image received by the A and A ′ planes has a light amount distribution waveform as shown in FIGS. In contrast to FIG. 11B, which is in focus depending on the position of the lens, the light amount distribution is as shown in FIGS. 11A and 11C before and after the lens. In some cases, the subject image is formed in a separated state.
Based on this principle, the phase difference calculation is performed to determine how much the subject image is deviated from the focus position, and the focus detection operation is performed.
In the present embodiment based on the above principle, in order to detect the phase difference in the cross direction, the planes A and A ′ in FIG. 2 are used as areas for detecting the phase difference in the horizontal direction, and the planes B and B ′ are in the vertical direction. As an area for detecting the phase difference, the re-imaging lens 122 performs the spectrum and projects the subject image in each area.

FIG. 13 is a diagram illustrating a configuration example of a focus detection region on the focus detection sensor surface of the focus detection apparatus according to the present embodiment.
FIG. 14 is a diagram illustrating an arrangement example of focus detection areas in the focus detection sensor of the focus detection apparatus according to the present embodiment.

As described above, the A and A ′ planes are areas for detecting the phase difference in the horizontal direction, and the B and B ′ planes are areas for detecting the phase difference in the vertical direction. The subject images that have passed through the re-imaging lens 122 are received by the A, A ′, B, and B ′ surfaces, respectively, and are arranged as shown in FIG. 13 in order to detect the horizontal phase difference on the A and A ′ surfaces. Detection is performed using the pixel area.
Similarly, in order to detect the phase difference in the vertical direction on the B and B ′ planes, detection is performed using the pixel areas arranged as shown in FIG.
In the present embodiment, the A, A ′, B, and B ′ planes are configured by area sensors, and each area sensor is divided into 15 blocks.

As described above, in the present embodiment, the focus detection area is 15 points, and the phase difference in the horizontal direction and the vertical direction is detected at all 15 points.
Further, as shown in FIG. 5, in order to detect the vertical phase difference on the A and A ′ planes in the focus detection area sensor 123, a pair of image signals on the A and A ′ planes are used as a phase difference. To detect. In order to detect the phase in the horizontal direction on the B and B ′ planes, B and B ′ are paired to detect a deviation of the image signal as a phase difference.
Although focus detection is performed with a configuration in which one focus detection area is arranged in 15 blocks as shown in the figure, the number of focus detection areas and their arrangement are free, and it corresponds to multipointing. Therefore, two focus detection areas can be arranged or set in one block.

FIG. 15 is a diagram illustrating a specific configuration example of the focus detection sensor 123 of the focus detection device 120.
As described above, the light beam that has passed through the re-imaging lens 122 forms an image on the A, A ′, B, and B ′ surfaces of the sensor 123. The A, A ′, B, and B ′ planes photoelectrically convert an image of a subject received by an area sensor in which photodiodes are two-dimensionally arranged.
The subject image received by the focus detection sensor 123 is photoelectrically converted, transferred to a memory, and output in accordance with an instruction from the controller 130 outside the focus detection device.
Information is transferred and stored in the memory MA by the sensor surface A, and information is transferred and stored in the memory MA ′ by the sensor surface A ′.
Information is transferred and stored in the memory MB by the sensor surface B, and information is transferred and stored in the memory MB ′ by the sensor surface B ′.
As described above, the sensor unit includes a light receiving unit that performs photoelectric conversion and an internal memory that stores the photoelectrically stored data. The sensor unit receives the accumulation start signal from the controller 130 and starts accumulation. The area sensors A, A ′, B, and B ′ are divided into 15 blocks, and monitoring is performed to monitor the accumulation state for each block, and accumulation is performed while detecting the maximum value and the minimum value. When the accumulation is completed, the accumulated data is written in the memories MA, MA ′, MB, MB ′, and the accumulated data is output in accordance with an instruction from the controller 130 to perform analog / digital (AD) conversion. Based on this output data, a phase difference calculation is performed to perform focus detection.

  In the present embodiment, the focus sensor 123 is supplied with the external minimum value ExtMin of the accumulation level supplied from the outside. The external minimum value ExtMin can be supplied from the controller 130.

As will be described in detail later, the focus detection apparatus 120 of the present embodiment includes a maximum value detection unit that detects an exposure maximum value of each divided block of an area sensor in which a light receiving unit is two-dimensionally arranged, and a division A minimum value detection unit for detecting the exposure minimum value of each block, an external minimum value input unit for inputting an external minimum value ExtMin from the outside, and an exposure minimum value and an external minimum value input unit output from the minimum value detection unit A monitor signal is generated from the selection unit that selectively outputs the external minimum value ExtMin input from the input unit, the exposure maximum value output from the maximum value detection unit, and the exposure minimum value or external minimum value output from the selection unit. And a monitor output unit.
The focus detection device 120 further includes a block selection unit that designates at least one of a plurality of divided blocks, and the monitor output unit sequentially outputs the monitor signal of each block for each block at a common output terminal. When a block is selected by the block selection unit, the monitor signal of the selected block is output to a common output terminal as needed.
Specifically, the monitor output unit outputs a monitor signal in order of each block read from the area sensor when a block is not designated by the block selection unit, and a specific block is selected by the block selection unit. In the case of interruption, the monitor signal of a specific block is interrupted in the order of blocks and is output to a common output terminal.

That is, the focus detection device 120 according to the present embodiment externally outputs a voltage equivalent to the minimum accumulation level of the focus detection area when the minimum accumulation level in the divided block of the focus detection area is not in the vicinity of the focus detection area. By supplying the level, the voltage level from the outside can be reduced from the accumulation level of each pixel, and only the contrast component can be extracted.
Further, it is possible to select for each block whether to reduce the minimum accumulation level of the divided blocks or to reduce the minimum accumulation level supplied from the outside, and it is possible to arbitrarily set.

  16A to 16C are diagrams illustrating an example for extracting a contrast component for one block obtained by dividing the area sensor into 15 blocks.

In the focus detection apparatus 120 according to the present embodiment, when accumulation is started, monitoring is performed for monitoring the accumulation state for each block.
The monitor detects the maximum value of the block accumulation level in order to prevent the photoelectric conversion element from being saturated. Further, the minimum value of the block is detected in order to extract the contrast component. The configuration is such that the accumulation level of all the pixels in one block is detected in order by detecting the maximum value, and the accumulation is stopped when the maximum value reaches a predetermined level.
As for the detection of the minimum value, similarly to the detection of the maximum value, the accumulation levels of all the pixels in one block are sequentially detected to detect the minimum value level.
Since a subject with a small contrast difference includes an unnecessary accumulation level component, as shown in FIG. 16A, a signal sufficient as the contrast necessary for the original phase difference calculation cannot be obtained.
By subtracting the minimum accumulation level of the focus detection area, this unnecessary component is removed. By amplifying and outputting this signal, an output signal obtained by extracting only the contrast component is obtained as shown in FIG. can get.

  17A and 17B show the case where the minimum value in one block of 15 blocks that divide the area sensor is subtracted and the minimum value level from the outside in the process of subtracting the minimum value for extracting the contrast component. It is a figure for demonstrating the example which supplies and subtracts the equivalent voltage to a sensor part.

Originally, in the focus detection apparatus, the focus detection area is fixed and focus detection is performed using a linear sensor. However, in the present embodiment, as described above, an area sensor is used to cope with multipointing. Thus, the focus detection area can be set freely.
As in this embodiment, the area sensor includes a portion other than the focus detection region that is actually used, and only the focus detection region portion is extracted to perform the phase difference calculation.
As shown in the figure, when the focus detection area is arranged in one block obtained by dividing the area sensor and the accumulation level has a minimum value in a portion other than the focus detection area, the contrast component of the subject has reduced the minimum value of the focus detection area. However, since the minimum value of the block is subtracted, the accumulation level which is not the original minimum value of the subject is reduced, and a sufficient contrast component cannot be obtained.
In order to avoid this problem, in this embodiment, as shown in FIG. 17A, when the minimum value of the block is away from the subject, a level equivalent to the minimum value of the accumulation level is supplied from the outside. Extract contrast components.
Once the focus detection area accumulation data is output, and there is a difference between the minimum value level of the block and the accumulation level of the focus detection area, a voltage level equivalent to the minimum value level of the focus detection area is supplied externally to Subtract from the accumulation level of the detection area.
As shown in the figure, only the contrast component is extracted, and this signal is amplified and output, so that a sufficient signal can be obtained for detecting the phase difference of the subject, and more accurate focus detection can be performed.

The controller 130 is mainly composed of a microcomputer, is connected to the focus detection sensor 123 of the focus detection device 12, and controls the focus detection sensor 123 by a control signal and a communication command.
Control signals of the controller 130 include a CG signal for starting accumulation, an ABSEL signal for selecting the horizontal and vertical detection directions, an AS0-AS3 signal for selecting a focus detection area, and Vout for outputting an image signal.
In the focus detection sensor 123, the image signal of the subject whose accumulation has been completed is transferred to the memories MA, MA ′, MB, MB ′, and then output to the controller 130 by the control signal and the communication command. The output signal is A / D converted by the controller 130 in synchronization with the clock signal from the focus sensor 123, the phase difference calculation is performed, and focus detection is performed.

  The multipoint focus detection is performed with the above configuration.

  Hereinafter, a specific configuration example of the focus detection device 120 including the photoelectric conversion device according to the present embodiment will be described.

  FIG. 18 is a diagram illustrating an example of a circuit block diagram of the focus detection device (photoelectric conversion device) 120 and the controller 130 that controls the focus detection device 120 according to the present embodiment.

As shown in FIG. 18, the focus detection device 120 includes an area sensor 200 having a pair of light receiving surfaces 200a and 200b, a timing generator 202, a serial interface (serial I / F) 203, and a control signal interface (control signal I). / F) 204 and a sensor signal processing unit 210.
As will be described later, the area sensor 200 is divided into a plurality of blocks as described above, and is operable for each block. The focus detection device 120 includes a sensor signal processing unit 210 for each block into which the area sensor 200 is divided.

The sensor signal processing unit 210 includes a maximum value detection unit 211 as a maximum value detection unit, a minimum value detection unit 212 as a minimum value detection unit, a minimum value sample hold unit 213, a maximum value comparison unit 214, and a maximum value. A minimum value differential unit 215, a sensor data / minimum value SH differential unit 216, a sensor output / monitor output switching unit 217 serving as a monitor output unit and a sensor signal output unit, and an amplifier 218. (Dotted line portion in FIG. 18).
The controller 130 includes a CPU 131 and a memory 132. The controller 130 includes the A / D converter described above.

  Hereinafter, the above-described components of the focus detection device 120 and the controller 130 will be described.

The area sensor 200 is a part of a two-dimensionally arranged focus detection photoelectric conversion element such as a CCD, and is composed of a pair of area sensor light receiving surfaces 200a and 200b.
As described above, the area sensor 200 can be operated in units of predetermined blocks, and the focus detection device 120 is designated by the controller 130 through the serial interface 203 for the coordinates of each block.

The timing generator 202 is a pulse generator that drives the area sensor 200 and generates a pulse corresponding to a frequency at which each function in the focus detection device 120 operates.
The serial interface 203 includes an interface circuit for performing serial communication with the CPU 131 of the controller 130. The focus detection device 120 performs an operation setting of the area sensor 200 based on each command transmitted from the CPU 130 by serial communication.
Hereinafter, each command transmitted by serial communication will be described.

(1) Block coordinate designation command This is a command for transmitting the X and Y coordinates of each block corresponding to the area sensor 200 from the CPU 130 and determining the area of each block. The CPU 130 that issues this command corresponds to the division designation means of the present invention.
In the present embodiment, the maximum number of blocks is 15. However, any number of blocks can be set as long as it is 15 blocks or less.
In addition, the boundary of each block may be in contact, and the boundary of each block may not be in contact.
(2) Block Coordinate Reading Command When the block of the area sensor 200 is designated from the CPU 130, this is a command that enables the coordinate value of the designated block to be read from the focus detection device 120.
(3) Each Block Accumulation Status Reception Command When this command is transmitted from the CPU 130, it is possible to read information on whether or not each block of the area sensor 200 is currently accumulating charges.
As will be described later, when the output signal level of the maximum value detection unit 211 reaches a predetermined upper limit value, the focus detection device 120 may automatically stop accumulation in units of blocks. This command is set so that the controller 130 can obtain information as to whether the charge is accumulated or stopped.
(4) Sensor data output rate selection command By transmitting this command from the CPU 130, the data output rate of the area sensor 200 can be selected. In this embodiment, the transfer rate can be selected from 1/16, 1/64, 1/128, 1/256, and 1/512 of the master clock.
(5) Accumulation Stop Command When the CPU 130 designates an arbitrary block of the area sensor 200 by this command, the focus detection device 120 stops the charge accumulation of the designated block.
The CPU 130 that transmits this command corresponds to the storage end unit of the present invention.

The control signal interface 204 includes an input / output terminal through which the focus detection device 120 exchanges control signals with the controller 130.
FIG. 19 is a diagram showing input / output terminals (terminals) included in the control signal interface 104, where (A) shows the names of the terminals, (B) shows the input / output of signals at the terminals, and (C) shows the inputs and outputs. The functions corresponding to each terminal are shown.
In this embodiment, control signals are exchanged through the terminals CG, CH, TH, TM, AT, OM, AS1-4, and AGC0-2 in FIG.
In FIG. 19B, a signal at a terminal indicated as IN is a signal input from the controller 130, and a signal at a terminal indicated as OUT is a signal output to the controller 130.
In FIG. 19B, VDD and VSS which are terminals described as PWR are terminals connected to a power supply voltage and a ground voltage, respectively, and VOUT described as OUT is a monitor output or sensor which will be described later. These are analog output terminals for output, and are not control signals.

Hereinafter, the control signal illustrated in FIG. 19A will be described.
The control signal CG is a control signal that instructs the controller 130 to start accumulation of the area sensor 200 (L level: accumulation start, H level: non-accumulation).
For example, when the CPU 131 of the controller 130 changes the CG terminal of the focus detection device 120 from H level to L level, the focus detection device 120 recognizes the level change via the control signal interface 204 and Charge accumulation is started for all blocks.
The CPU 131 that transmits the control signal CG corresponds to an accumulation start unit of the present invention.

  The control signal CH is a control signal output from the focus detection device 120 and indicates whether or not at least one of the blocks is being accumulated (L level: all blocks are not accumulated, H level: at least 1). Blocks are accumulating). The controller 130 can know the storage status of each block by the above-mentioned “each block storage status reception command” and this control signal.

The control signal TH is a control signal for instructing the transfer start from the controller 130 (L level: transfer start, H level: non-transfer). Normally, after the accumulation is completed, the transfer target block is designated and the transfer start is instructed at the timing when the transfer of sensor data from the focus detection device 120 is started.
The control signal TM is a control signal output from the focus detection device 120 and indicates whether or not sensor data is being transferred (L level: non-transfer, H level: being transferred).

The control signal AT is a pulse waveform control signal output from the focus detection device 120, and the CPU 131 of the controller 130 sequentially outputs sensor data in units of pixels output from the focus detection device 120 in synchronization with the control signal AT. D-convert. Specifically, the CPU 131 starts A / D conversion at the timing when the control signal AT changes from H level to L level.
The control signal OM is a control signal instructed by the controller 130, and thereby, switching of sensor output or monitor output in the sensor output / monitor output switching unit 217 is controlled (L level: monitor output selection, H level: Sensor output (pixel output) selection). Normally, the monitor output is selected during the accumulation control, and when the accumulation is completed, the sensor output is selected to extract the sensor signal.

The control signals AS1 to AS4 are control signals instructed by the controller 130, and instruct block selection for the signal VOUT (monitor output or sensor output) output from the amplifier 218. In the present embodiment, since the output terminal for the signal VOUT is common to the sensor signal processing unit 210 corresponding to each block, the control signal AS1 to 4 is used to determine which block is output. 130 selects.
Each of the control signals AS1 to AS4 constitutes 4-bit data corresponding to the signal level (L level: “0”, H level: “1”). For example, if AS1: “L”, AS2: “H”, AS3: “L”, AS4: “L”, block 4 is selected (see FIG. 19C).
The CPU 131 that transmits the control signals AS1 to AS4 corresponds to the block selection unit of the present invention.

The control signals AGC0 to AGC2 are control signals instructed by the controller 130, and mean the degree of amplification of sensor data or monitor data output from the amplifier 218.
Each of the control signals AGC0 to AGC2 constitutes 3-bit data corresponding to the signal level (L level: “0”, H level: “1”). For example, if AGC0: “L”, AGC1: “H”, and AGC2: “L”, an amplification factor (gain) of 20 times is designated (see FIG. 19C).
Note that the gain can be selected independently for each block by the control signals AGC0 to AGC2.

As shown in FIG. 18, the maximum value detection unit 211 detects the maximum value of the output signal level of the light receiving unit 200b of the area sensor 200.
As shown in FIG. 18, the minimum value detection unit 212 detects the minimum value of the output signal level of the light receiving unit 200 b of the area sensor 200.
Note that the maximum value detection unit 211 and the minimum value detection unit 212 may detect the signal output of one of the pair of light receiving units 200a and 200b of the area sensor 200. This is because the same image is formed on each surface of the pair of area sensor light receiving portions 200a and 200b by the re-imaging lens 122, and only one surface needs to be monitored. In the present embodiment, as shown in FIG. 18, the area sensor light receiving surface 200b is monitored.

  The minimum value sample hold unit 213 samples and holds the output signal S212 of the minimum value detection unit 212 in synchronization with a signal having a predetermined frequency generated by the timing generator 202 (sample hold).

The maximum value comparison unit 214 compares the output signal S211 of the maximum value detection unit 211 with a predetermined saturation level (stop level) in order to avoid saturation of accumulation in the area sensor 200, and the output signal S211 has a saturation level. When exceeding, that is, when it is determined that the charge accumulation of the area sensor 200 has reached the saturation level, the output signal S214 is set to the L level.
The sensor signal processing unit 210 is provided for each block, and the maximum value comparison unit 214 of the sensor signal processing unit 210 corresponding to each block determines whether or not the accumulation has reached a saturation level. That is, the determination whether or not the saturation level has been reached is performed independently for each block.

The focus detection device 120 stops the charge accumulation without waiting for the “accumulation stop command” from the controller 130 for the block in which the output signal S214 of the corresponding maximum value comparison unit 214 has changed from the H level to the L level. .
The reason why the accumulation is automatically stopped on the focus detection device 120 side when the saturation level is reached is because the accumulation control delay of the controller 130 based on the monitor output (VOUT) described later is taken into consideration.
That is, the controller 130 controls accumulation based on a monitor output (signal S215) described later. However, since each block is processed in chronological order, it is assumed that there is a delay in the accumulation control. Since this control delay is caused by the control cycle, subject brightness, contrast, and the like, it is difficult to quantitatively grasp the control delay. Therefore, even when a delay occurs in the control, in order to avoid accumulation saturation in the sensor, as described above, when the saturation level is reached, the accumulation operation is automatically stopped on the focus detection device 120 side. I have decided.

  The maximum value / minimum value differential unit 215 subtracts the output signal of the maximum value detection unit 211 and the output signal of the minimum value detection unit 212 (signal S215) via the sensor output / monitor output switching unit 217. To the amplifier 218.

FIG. 20 is a diagram illustrating the state of the monitor output signal according to the passage of time, (A) shows the change of the signal level of the output signals S211 and S212 with the passage of time, and (B) shows the output. Changes in the signal level of the signal S215 (monitor output) with the passage of time are shown.
As shown in FIG. 20, since the exposure amount increases as the charge accumulation time elapses, both the output signal S211 of the maximum value detection unit 211 and the output signal S212 of the minimum value detection unit 212 increase (FIG. 20A )). A monitor output S215 obtained by calculating a difference value from these output signals S211 and S212 is output as shown in FIG.

  The sensor data / minimum value SH differential unit 216 calculates and outputs a difference value between the sensor output of the area sensor light receiving surface 200a and the output signal S212 of the minimum value detection unit 212 sampled and held by the minimum value sample hold unit 213. (Signal S216).

The sensor output / monitor output switching unit 217 is either an output signal S215 (monitor output) of the maximum / minimum value differential unit 215 or an output signal S216 (sensor output) of the sensor data / minimum value SH differential unit 216. It has a switch function that enables signal selection.
Switching of signal selection can be performed by a control signal OM (OM signal) supplied from the controller 130 as shown in FIG. That is, when the OM signal is at the H level, the sensor output is selected, and when the OM signal is at the L level, the monitor output is selected.

The amplifier 218 outputs the signal (monitor output or sensor output) selected by the sensor output / monitor output switching unit 217 according to the amplification degree (gain) designated by the control signals AGC0 to AGC to the A / D of the CPU 131 of the controller 130. Output to the conversion unit (signal VOUT).
As described above, when the OM signal that is a control signal from the controller 130 is at the L level, the sensor output / monitor output switching unit 217 selects the monitor output, and the amplifier 218 amplifies and outputs the monitor output.
At that time, if the output terminals are arranged for each block, the number of terminals becomes enormous, resulting in an increase in the size of the focus detection device 120, and variations in the output signal of each block due to variations in the output circuit characteristics of each terminal. Therefore, in order to avoid this, in this embodiment, the output terminal is one terminal, that is, the output circuit is common to all the blocks, and the block is appropriately designated and output.

The controller 130 includes a CPU 131 and a memory 132.
The CPU 131 transmits a control signal to each terminal of the focus detection device 120 and controls charge accumulation of the focus detection device 120 of the focus detection device 120. Further, the CPU 131 performs serial communication with the focus detection device 120 and sets the accumulation operation in the area sensor 200.
Further, when the area sensor 200 of the focus detection device 120 is accumulating charges, the CPU 131 inputs the monitor output of each block as VOUT and controls the charge accumulation. That is, the CPU 131 converts the monitor output VOUT into a digital signal by a built-in A / D converter, determines the accumulation level (accumulation amount), and if the accumulation level reaches a predetermined level, the block is displayed. The designated accumulation stop command is sent to the focus detection device 120.

Further, the CPU 131 performs gain setting according to the accumulation time and the monitor output for each block, and stores the gain setting in the memory 131.
That is, when the subject is dark or when the contrast is low, it takes time to obtain a sufficient accumulation amount, so that an optimum gain setting corresponding to the accumulation time and the monitor output is performed for each block. For example, the gain is set to be small when the contrast is large, and the gain is set to be large when the contrast is small. As a result, even when the contrast is small, a predetermined signal level can be obtained early while suppressing the accumulation time.
After the charge accumulation is stopped in the area sensor 200, the sensor output is input as VOUT, and the input sensor output is converted to digital and processed using the control signal AD from the focus detection device 120 as a trigger. At that time, the gain for each block stored in the memory 132 is read and applied.

  The memory 132 includes a nonvolatile memory such as an EEPROM, and stores the gain setting value of the amplifier 218 of the focus detection device 120 for each block of the area sensor 200.

Heretofore, the components of the focus detection device 120 and the controller 130 have been described.
Next, the operation of the photoelectric conversion device in this embodiment is related to the timing charts of FIGS. 21A to 21N, 22A to 22N, and 23A to 23N. explain.
FIGS. 21, 22, and 23 are timing charts for explaining the operation of the focus detection apparatus according to the present embodiment. FIG. 21, (A) shows the power-on state of the focus detection apparatus 120, and (B) shows the reset. (RST) signal (L: active), (C) master clock (MCLK) signal, (D) communication state performed by serial interface 203, (E) control signal CG, and (F) control signal. CH, (G) the storage state of each block of the area sensor 200, (H) the output signal VOUT (monitor output / sensor output), (I) the control signal OM, (J) the control signal AS1. -4, (K) indicates the control signals AGC0-2, (L) indicates the control signal TH, (M) indicates the control signal TM, and (N) indicates the control signal AT.
Each signal changes in time series from FIG. 21 to FIG.

As shown in FIG. 21A, when the power source of the focus detection device 120 is activated at time t0, the reset signal soon becomes H level (FIG. 21B), and the master clock having a predetermined frequency operates. By doing so (FIG. 21D), each function of the focus detection device 120 becomes operable.
First, as shown in FIG. 21D, the controller 130 performs initial setting of the focus detection device 120 by serial communication via the serial interface 203.

  As an initial setting, for example, block designation for the area sensor 200 is performed by a block coordinate designation command. As described above, the area sensor 200 is operable for each designated block. In this description, it is assumed that the block is specified to be divided into 15 blocks so that the divided areas of the respective blocks are in contact with each other.

In FIG. 22, at time t1, the CPU 131 of the controller 130 instructs the focus detection device 120 to accumulate charges. That is, as shown in FIG. 22E, the CPU 131 changes the control signal CG from the H level to the L level.
Thereby, the focus detection apparatus 120 starts charge accumulation of all the blocks of the area sensor 200 all at once, and accordingly, as shown in FIG. 22 (G), each of the blocks BLK1 to 15 of the area sensor 200. The block is in charge accumulation (H level) after time t1.
Further, as shown in FIG. 22F, the control signal CH representing the accumulation signal is H level when at least one block is accumulating charges, that is, the OR logic of the charge accumulation state of all the blocks. Since the value is output, the control signal CH becomes H level soon after time t1.

The accumulated amount monitor signal (monitor output) VOUT shown in FIG. 22 (H) is a maximum value (signal S212) which is a signal output by the maximum value detector 211 and the minimum value detector 212 provided for each block. , The difference value of the minimum value (signal S212) is calculated by the maximum value / minimum value differential unit 215 and output.
At this time, the blocks of the predetermined area sensor 200 are designated by the control signals AS1 to AS4 (FIG. 22 (J)) transmitted from the controller 130, and the control signals AGC0 to AGC2 to 2 (FIG. 22 (K) Since the gain corresponding to each designated block is designated by ()), the monitor output VOUT corresponding to these control signals is output.
The monitor output VOUT for each block is converted into a digital signal by an A / D converter built in the CPU 131, and the CPU 131 determines the accumulation level (accumulation amount). That is, it is determined whether or not the monitor output VOUT is equal to or higher than a predetermined level and the accumulation level is sufficient.
During the accumulation operation, even when the block select signals (AS1 to AS4) are switched, the monitor signals of each block are sequentially A / D converted, and the accumulation amount is judged and controlled from the result. .

22, at time t2, as shown in FIG. 22G, the second block (BLK2) of the area sensor 200 automatically stops accumulation (maximum value automatic stop) to avoid accumulation saturation. ) And the accumulation state is turned off (L level).
That is, the output signal S211 of the maximum value detection unit 211 of the sensor signal processing unit 11 provided for the second block (BLK2) is compared with a predetermined saturation level (stop level) in the maximum value comparison unit 214, When the output signal S211 exceeds the saturation level, that is, when it is determined that the charge accumulation of the area sensor 200 has reached the saturation level, the output signal S214 is set to the H level.
As a result, the focus detection device 120 stops the accumulation of the area sensor 200 only in the second block (BLK2).

During charge accumulation, when the CPU 131 of the controller 130 transmits “each block accumulation status reception command” requesting information about whether or not each block is accumulating, the command is transmitted as shown in FIG. The received focus detection device 120 monitors the output signal S214 of the maximum value comparison unit 214 of the sensor signal processing unit 210 corresponding to each block, and determines whether or not each block is accumulating (accumulation state). The result is returned to the controller 130 by serial communication ("Accumulation status reception" in FIG. 22D).
As described above, when the focus detection apparatus 120 stops the accumulation of only the second block (BLK2), the controller 130 responds to the “each block accumulation status reception command” in response to the second block (BLK2). ) Accumulation can be recognized.

In FIG. 22, at time t3, the CPU 131 determines that the accumulation level (accumulation amount) is sufficient when the monitor output VOUT for successive A / D conversion reaches a predetermined level, and An “accumulation stop command” is transmitted (“accumulation stop” in FIG. 22D).
The “accumulation stop command” can stop the accumulation by designating a block by the control signals AS1 to AS4. However, in the example shown in the timing chart of FIG. 22, the accumulation level of all the blocks is sufficient. This shows a case where the judgment is made and accumulation of all blocks is stopped.
That is, the CPU 131 of the controller 130 sends out an “accumulation stop command” designating all blocks by serial communication, and the focus detection device 120 that has received the “accumulation stop command” then stops accumulating all blocks.
Further, as shown in FIG. 22F, when the accumulation of all the blocks is stopped and the accumulation state is turned off (BLK 1 to 15 in FIG. 22G are all at L level), the signal of the accumulation state of each block Since the control signal CH indicating the OR logical value of the signal changes from the H level to the L level (FIG. 22F), the controller 130 monitors the control signal CH, so that the accumulation state of all the blocks is in the OFF state. It can be confirmed that (accumulation stop) has been reached.

Since the accumulation operation is completed by the above operation, the sensor signal of the area sensor 200 is output next. In order to output the sensor signal of the area sensor 100, it is necessary to select the sensor signal in the sensor output / monitor output switching unit 217 of the focus detection device 120.
Therefore, as shown in FIG. 22I, CPU 131 of controller 130 changes control signal OM from the L level to the H level at time t4.
As a result, in the focus detection device 120, the sensor output / monitor output switching unit 217 switches the monitor signal (monitor output) to the sensor signal (sensor output), and the sensor data / minimum value SH differential unit 216 The output signal S216, that is, the difference value between the sampled and held minimum value signal (S213) and the sensor signal is amplified by the amplifier 218 and output as VOUT (FIG. 22 (H)).

At that time, the controller 130 first transmits a “sensor data output rate selection command” to the focus detection device 120 by serial communication, and designates the transfer rate of the sensor output VOUT. As described above, the transfer rate can be set from 1/16, 1/64, 1/128, 1/256, and 1/512 of the master clock (MCLK). Select / designate transfer rate according to / D conversion speed and send the above command.
Further, the controller 130 designates blocks to be output to the focus detection device 120 by the control signals AS1 to AS4.

Then, the controller 130 designates the gain at the end of accumulation stored in the memory 132 as the gain of the amplifier 218 of the block to be output by the control signals AGC0 to AGC2.
As described above, the gain for each block is set to be large when the light / dark difference is small and small when the light / dark difference is large. / D conversion can be performed.
For example, even if a 100: 90 subject is A / D converted at a resolution of 100, only a signal of 90 to 100 is obtained, but if it is amplified 10 times and A / D converted, a signal of 0 to 100 is obtained. This is equivalent to using an A / D converter having 10 times the resolution, and A / D conversion can be performed with high accuracy.

Then, as shown in FIG. 22 (L), when the controller 130 sets the control signal TH to the L level at time t5, the focus detection device 120 outputs the sensor data (sensors) of the block designated by the control signals AS1 to AS4. Output).
At that time, as shown in FIG. 22 (N), in synchronization with the control signal AT output from the focus detection device 120 side, the CPU 131 of the controller 130 captures the output of each pixel and performs A / D conversion. . That is, the pixel signal output from the focus detection device 120 is switched at the timing when the control signal AT having the pulse waveform shown in FIG. 22N is switched from the L level to the H level, and the control signal AT is converted from the H level to the L level. At the timing, since the sensor data of each pixel becomes stable, the CPU 131 starts A / D conversion at the timing when the control signal AT changes from H level to L level.
In the example shown in FIG. 22, as shown in FIG. 22 (J), the first block (BLK1) is first selected, the sensor data is taken in, and A / D conversion is performed.

After time t5, as shown in FIG. 23, each block is sequentially selected by the controller 130, sensor data VOUT of each block of the focus detection device 120 is taken into the controller 130, and A / D conversion is performed.
In FIG. 23, as shown in (J), blocks 6 and 7 are designated, and sensor data VOUT of each block is taken into the controller 130 and A / D conversion is performed.

Note that the transfer of the sensor data of each block stops when the output of the data of all the pixels of each block is completed.
Even if the data output of all the pixels in each block has not been completed, the controller 130 can return to the H level from the L level to stop halfway at that time. In other words, after extracting the necessary data from the sensor output of each block, the controller 130 stops the data transfer so that the data transfer of the unnecessary part can be stopped and the next processing can be performed immediately. (Data transfer stop processing).
As a result, the data transfer time is shortened, and the overall processing time can be shortened.

Also, as shown in FIG. 23D, in order to speed up the data transfer process, the controller 130 switches the data transfer rate as appropriate by the “sensor data output rate selection command”. That is, among the sensor data of each block, the transfer rate is set to the maximum speed except for the necessary part data, and the transfer rate is reduced to a speed at which the CPU 131 can perform A / D conversion for the necessary part data. Control.
As a result, like the data transfer stop process described above, the sensor data transfer is shortened, and the entire processing time can be shortened.

The focus detection device 120 according to the present embodiment, when the minimum accumulation level in the divided block of the focus detection area is not in the vicinity of the focus detection area, is externally equivalent to the minimum accumulation level of the focus detection area. By supplying the level, the voltage level from the outside can be reduced from the accumulation level of each pixel, and only the contrast component can be extracted.
Further, it is possible to select for each block whether to reduce the minimum accumulation level of the divided blocks or to reduce the minimum accumulation level supplied from the outside, and it is possible to arbitrarily set.
As described above, in the focus detection apparatus 120 according to the present embodiment, when accumulation is started, monitoring is performed for monitoring the accumulation state for each block.
The monitor detects the maximum value of the block accumulation level in order to prevent the photoelectric conversion element from being saturated. Further, the minimum value of the block is detected in order to extract the contrast component. The configuration is such that the accumulation level of all the pixels in one block is detected in order by detecting the maximum value, and the accumulation is stopped when the maximum value reaches a predetermined level.
As for the detection of the minimum value, similarly to the detection of the maximum value, the accumulation levels of all the pixels in one block are sequentially detected to detect the minimum value level.
An object with a small contrast difference includes an unnecessary accumulation level component, so that a signal sufficient as the contrast necessary for the original phase difference calculation cannot be obtained.
This unnecessary component is removed by subtracting the minimum accumulation level of the focus detection area, and this signal is amplified and output to obtain an output signal from which only the contrast component is extracted.

Hereinafter, the focus detection operation will be described with reference to the flowcharts of FIGS. FIG. 24 is a flowchart for explaining an outline of the operation according to the present embodiment.
FIG. 25 is a flowchart for explaining the focus state accumulation state monitoring operation according to the present embodiment.
FIG. 26 is a flowchart for explaining the accumulated data output operation for focus detection according to this embodiment.

First, as shown in FIG. 24, the camera is turned on (ST101), and a focus detection area is selected (ST102).
There are 15 focus detection points, all of which can be detected in the cross direction. In step ST102, a mode for selecting one point, a mode for selecting all points, and the like are selected.
Next, the focus detection operation is started by capturing the subject and pressing the release button to the first level (ST103).
When focus detection is started, first, an image of the subject is received by the focus detection device, and accumulation is started on the sensor surface (ST104).
The focus detection device 120 according to the present embodiment incorporates a function for monitoring the accumulation state of the sensor, and performs control while determining whether or not the accumulation level has reached an appropriate state (ST105).
When the accumulation state is deemed appropriate, the accumulation is terminated (ST106). When the accumulation ends, the sensor of the focus detection device 120 writes the accumulated data to the memory inside the sensor. The written data is output from the Vout terminal in accordance with an instruction from the control unit (ST107).
At this time, since the output from the Vout terminal extracts and outputs only the contrast component, the correlation calculation (ST109) for detecting the phase difference is performed inside the sensor. The lens is driven from the amount of focus shift obtained from the correlation calculation (ST110).
This step ST104ST110 is repeated to perform the focusing operation.

FIG. 25 is a detailed flow chart in the storage state monitoring (ST105) of FIG.
In step ST105, the accumulation level is monitored for each block that divides the focus detection area of the sensor in order to monitor the accumulation state.
When accumulation is started, the maximum value (ST1051) and minimum value (ST1052) of all pixels of the block are detected inside the sensor as the accumulation state of the block in the selected focus detection area.
At this time, the minimum value of the block is stored in the memory inside the sensor in order to extract the contrast component (ST1053).
Then, the maximum value and the minimum value are output, and the accumulation level is determined from the signal (ST1054). When the accumulation level reaches an appropriate value, the accumulation ends. As described above, the maximum value and the minimum value of all the pixels of the block are detected for each block, and accumulation is controlled.

FIG. 26 is a detailed flow of output of accumulated data in FIG.
First, in step ST1071, it is determined whether the focus detection operation is the first accumulation operation. In this embodiment, in the first case, the minimum value of the block is reduced from the accumulation level of each pixel, and in the second and subsequent times, the voltage level supplied from the outside is reduced from the accumulation level of each pixel.
In the present embodiment, as described above, the minimum level of the block is reduced for the first time, and the voltage level from the outside is reduced after the first time. However, when the voltage level from the outside is reduced from the first time, There are cases where the level is constantly reduced.
This process determination can determine whether or not the pixel having the minimum accumulation level is located away from the focus detection area when the pixel level of the entire block at the time of monitoring the accumulation state is monitored.
Also, whether to extract the contrast component by subtracting the minimum value of this block from the accumulation level of each pixel or whether to extract the contrast component by subtracting the voltage level supplied from the outside from the accumulation level of each pixel depends on the block. For example, the controller 130 determines this and sets and outputs the accumulated data when outputting it.
The contrast component is extracted by subtracting the accumulation level of each pixel from the accumulation level to the minimum value of the accumulation level of the block or the voltage level supplied from the outside (ST1072, ST1073).
The contrast component is amplified inside the sensor when output (ST1074), and the amplified signal is output from the output (Vout) terminal (ST1075).

As described above, according to this embodiment, when the minimum accumulation level in the divided block of the focus detection area is not in the vicinity of the focus detection area, a voltage equivalent to the minimum accumulation level of the focus detection area from the outside. By supplying the level, the external voltage level is subtracted from the accumulation level of each pixel, only the contrast component is extracted, and the minimum accumulation level of the divided block is reduced, or the minimum accumulation level supplied from the outside Since it has the focus detection apparatus 120 which can be selected for every block and can be set arbitrarily, the following effects can be acquired.
For a subject under low luminance or a subject with a small contrast difference, only effective contrast components can be extracted and correlation calculation can be performed, and a more accurate focusing operation can be performed. As a means for extracting the contrast difference, the minimum value of the block accumulation level is subtracted from the accumulation level of each pixel, or the voltage level equivalent to the minimum value level of the focus detection area supplied from the outside is accumulated in each pixel. By having a function of selecting whether to subtract from the level, there is an advantage that autofocus corresponding to the subject and the shooting environment thereof can be performed.

  In the present embodiment, the vertical and horizontal directions (that is, the cross) have been described as examples in the phase difference detection region. However, the same effect can be obtained even when diagonally right and left (that is, X-shaped).

Further, according to the photoelectric conversion device of the present embodiment, the output of one of the pair of light receiving surfaces 200a and 200b and the pair of area sensor light receiving surfaces 200a and 200b of the area sensor 200 on which the same image is formed. A maximum value detecting unit 211 for obtaining a maximum value, a minimum value detecting unit 212 for obtaining a minimum value, a maximum / minimum value differential unit 115 for calculating a difference value (monitor output) between the maximum value and the minimum value, and a minimum The minimum value sample hold unit 213 that samples and holds the minimum value output by the value detection unit 212, the minimum value sampled and held by the minimum value sample hold unit 213, and the other output of the pair of area sensor light receiving surfaces 200a and 200b Sensor data / minimum value SH differential unit 216 for calculating a difference value (sensor output) between the monitor output and a sensor output or a sensor output. A sensor output / monitor output switching unit 217, an amplifier 218 that amplifies and outputs the monitor output or sensor output, a serial interface 203 that performs serial communication with an external controller 130 including the CPU 131, and a control that receives a control signal from the CPU 131 When the focus detection device 120 has the signal interface 204 and the monitor output is selected by the control signal from the CPU 131, the controller 130 performs the accumulation control by the monitor output corresponding to the charge accumulation of the area sensor 200, and the accumulation is performed. When the operation is completed, the accumulation operation is stopped, and at the same time, the sensor output is selected and processed by the control signal from the CPU 131.
At that time, the focus detection device 120 designates block areas (sensor coordinates) of the area sensor light receiving surfaces 200a and 200b by the controller 130 via serial communication, and generates a monitor signal for each designated block. The output terminal is configured to be common to all blocks.
Therefore, the following effects can be obtained.

As described above, in the photoelectric conversion device of the present embodiment, the maximum value detection unit 211 and the minimum value detection unit 212 are set to either one of the pair of light receiving surfaces 200a and 200b of the area sensor 200 on which the same image is formed. Since it is configured as one, it is not necessary to take out monitor signals from the respective area sensors, and there is an effect in mounting that the circuit scale including wiring can be minimized.
In addition, while one area sensor is being monitored, the accumulation operation of the other area sensor is performed, so that the overall processing time is reduced and high-speed focus detection is possible.

  As described above, the maximum value detection unit 211 and the minimum value detection unit 212 are arranged for each block and share a monitor output terminal for each block. Therefore, compared with the case where each block has a monitor output terminal. The variation in output circuit characteristics between the blocks can be reduced, and the focus detection device 120 can be downsized.

  The block area designation (sensor coordinate designation) described above is set to a common coordinate for each area sensor light receiving surface 200a, 200b, and based on the accumulation control result of each block on one light receiving surface, Since the sensor output of the corresponding block of the same coordinate is processed, it is possible to perform highly accurate accumulation control according to the brightness and contrast for each block.

  The focus detection apparatus 120 according to the present embodiment starts accumulation of the area sensor 200 in response to a control signal (control signal CG) from the controller 130, receives a command (accumulation stop command) from the controller 130, and accumulates in the area sensor 200. When the accumulation is completed, a sensor signal is output. However, since these operations are performed independently by selecting and specifying a block, it is possible to perform optimum control for each block of the area sensor 100. It is. For example, when the accumulation level of a specific block reaches a sufficient state, the accumulation of only the specific block can be stopped.

In the photoelectric conversion apparatus of this embodiment, the gain of the amplifier 218 is set for each block by the controller 130 according to the accumulation time and the monitor output, so that the accumulation time is suppressed even when the subject is dark or the contrast is low. However, a predetermined signal level can be obtained promptly.
Also, the gain for each block is set to be large when the contrast is small and small when the contrast is large. Therefore, the sensor output VOUT for a subject with a small contrast is A / D converted with extremely high accuracy. Can be performed.

In the above, with reference to FIG. 18, it is possible to perform auto focus detection at a higher speed and higher accuracy over a wide area and save space, and only a contrast component is used for a low-brightness subject or a subject with little contrast difference. A focus detection apparatus has been described in which the focus detection accuracy can be improved and the focus accuracy can be improved, and the focus can be detected even on a low-luminance subject.
In the following, while maintaining the drooping characteristics of the edge of the sensor output signal due to the imaging of the oblique subject, the effective sensitivity can be made appropriate and the focus detection accuracy can be improved as much as possible. A focus detection apparatus that can extract only a contrast component from a small number of subjects, can improve the focusing accuracy, and can detect a focus even on a low-luminance subject will be described.

FIG. 27 is a diagram illustrating another example of a circuit block diagram of a focus detection device (photoelectric conversion device) 120A and a controller 130A that controls the focus detection device 120A according to the present embodiment.
In this figure, reference numeral 300 denotes an area sensor (focusing sensor). A CMOS type image sensor is used for the area sensor 300, and an XY address system is used in which the controller 130 performs X and Y scanning.

In this area sensor 300, each pixel is formed in a rectangular shape, but a first photodiode line 300a in which photodiodes having a small pixel area are arranged and a second photo diode in which photodiodes having a large pixel area are arranged. The diode lines 300b are arranged in multiple lines alternately arranged in the vertical direction.
In the drawing, for convenience of explanation, six lines are shown, but actually there are many lines.

Further, the area sensor 300 can simultaneously read out one line and two lines, and the reading configuration is shown in FIG.
28 shows the area sensor 300 in a simplified manner for convenience of explanation, the illustrated switch element (FET) SW1 is provided in each photodiode of the first photodiode line 300a, and the switch element (FET) SW2 is provided. Is provided in each photodiode of the second photodiode line 300b, and a floating gate is connected to each photodiode.

Therefore, the pixel signal of the first photodiode line 300a is read by sequentially applying the X scanning pulse ΦP1 to the gate of the switch element SW1 according to the first, third, and fifth lines to turn on each switch element SW1. be able to.
Similarly, if the X scan pulse ΦP2 is sequentially applied to the gate of the switch element SW2 in accordance with the second, fourth, sixth,... Lines, and each switch element SW2 is turned on, the pixels of the second photodiode line 300b. The signal can be read out.

  In addition, the area sensor 300 causes the pixel signal read from the first photodiode line 300a and the second photodiode line 300b to be manually operated by one pixel amplifier AP, and outputs the pixel amplifier AP to the Y scanning pulse ΦVS. Is output as a sensor output signal VO via a switch element (FET) SW3 which is turned on by the switch.

  Specifically, when only the switch element SW1 is turned on by supplying the X scan pulse ΦP1, a first readout circuit that reads out only the pixel signal of the first photodiode line 300a having a small pixel area is formed. If only the switch element SW2 is turned on by supplying the X scan pulse Φ2, a second readout circuit for reading out only the pixel signal of the second photodiode line 300b having a large pixel area is formed.

  Then, when the X scanning pulses ΦP1 and ΦP2 are supplied to turn on the switch elements SW1 and SW2, the pixel signals of the first photodiode line 300a and the second photodiode line 300b are read out simultaneously, and the pixels of these two lines A third readout circuit for adding signals by the pixel amplifier AP is formed.

  On the other hand, the focus detection apparatus includes a peak detection circuit 301 that detects the accumulated charge of the maximum light emitted to the area sensor 300 and a bottom detection circuit 302 that detects the accumulated charge of the minimum light of the light. It is.

  The peak signal VP output from the peak detection circuit 301 is compared with the stop level signal by the comparator 303, and when the peak signal VP exceeds the stop level, the saturation stop signal VS output from the comparator 303 is sent to the timing generator 304.

Specifically, the comparator 303 outputs a stop signal VS1 due to saturation by the peak signal VP when the area sensor 300 is close to saturation of charge accumulation due to the maximum light, and the timing generator 304 responds to the stop signal VS1. The charge accumulation of the area sensor 300 is stopped once (first accumulation stopping means).
The controller 130A receives the stop signal VS1 and confirms that the charge accumulation is stopped by the first accumulation stop means.

The peak signal VP and the bottom signal VB are input to an operational amplifier (differential amplifier circuit) 305, and a difference signal between the peak signal VP and the bottom signal VB is sent to the controller 130A.
That is, as shown in FIGS. 28 and 29, the peak signal VP and the bottom signal VB vary depending on the contrast of the subject (the light / dark difference of the light applied to the area sensor 300), and thus the difference signal between the peak signal VP and the bottom signal VB. Is input as the monitor signal VM to determine the contrast of the subject.

  When the monitor signal VM reaches a predetermined level within a predetermined time, the controller 130A sends a monitor stop signal VS2 to the timing generator 304, and the charge generation of the area sensor 300 is performed by the response operation of the timing generator 304. Is stopped (second accumulation stopping means).

Further, the controller 130A sends a stop signal VS3 based on the limit time to the timing generator 304 when the specified time has passed without the monitor signal VM reaching the predetermined level within the specified time.
In response to the stop signal VS3, the timing generator 304 forcibly stops the charge accumulation of the area sensor 300 (third accumulation stop unit).

The area sensor 300 stops the charge accumulation by any one of the first, second, and third accumulation means described above, and then the pixel signal is output by the first, second, and third readout circuits already described. It is read out and sent to the controller 130A as a sensor output signal VO.
The controller 130A receives the sensor output signal VO and calculates a focus detection signal according to the sensor output signal VO.
Then, a focus driving unit that responds to the focus detection signal moves the focus adjustment lens of the photographing optical system to bring it into focus.

The first, second, and third readout circuits are selected by the controller 31, and the readout operation is performed by any one of the readout circuits.
Specifically, the controller 31 counts the charge accumulation time of the area sensor 30 using a counter, and the first, second, and third accumulations described above as predetermined times t1, t2, and t3 (t1 <t2 <t3). The first, second, and third readout circuits are selectively operated in accordance with the charge accumulation stop of the stop means.

  That is, when the controller 130A operates the first accumulation stop means for less than t1 time, tl to t2 hours, and t2 to t3 hours, the second accumulation stop means for similarly less than t1 hours, tl to t2 hours, and t2 to t3 hours. Is operated, it is determined whether or not the third accumulation stop means has been operated after t3 time, and ΦP1 or ΦP2 or XP as an X scan pulse for operating any of the first, second, and third readout circuits according to the determination. ΦP1 and ΦP2 are output.

FIG. 31 is a flowchart showing the selection operation of the first, second, and third readout circuits performed by the controller 130A.
As shown in the figure, it is determined which readout circuit is in a readout state at the start of control of the area sensor 300, and the readout circuit is initially selected (steps ST500 and ST501).

Subsequently, charge accumulation in the area sensor 300 is started and counting of the charge accumulation time is started (steps ST502 and ST503).
After the charge accumulation is started, the process proceeds to a step of determining whether or not the charge accumulation is stopped by the saturation stop means (first accumulation stop means). When the accumulation stop is confirmed, the flag 1 (PEK) STP = 1) is set (steps ST504 and ST512).

  After setting the flag 1 as described above, counting of the charge accumulation time is stopped, the pixel signal is read by the initially selected readout circuit, sensor data transfer is performed, and the sensor output V0 is sent to the controller 130A. (Steps ST509 and ST510).

Subsequently, the process proceeds to the next photodiode selection step ST511, selects the first scan of the next scan, and returns to the sensor accumulation start step ST502.
The diode selection for the next scan will be delayed.

  On the other hand, in step ST504 for stopping accumulation due to saturation, when it is determined that the charge accumulation is not stopped within time t1, it is determined whether or not the monitor signal VM has reached a predetermined level within time t1 (step ST505).

Here, when it is confirmed that the monitor signal has reached a predetermined level, flag 1 (MON STP = 1) is set and charge accumulation is stopped by the second accumulation stop means (steps ST513 and ST508).

Thereafter, in the same manner as described above, the storage time is stopped, the sensor data is transferred, and the next photodiode selection steps ST509, ST510, and ST511 are returned to the sensor accumulation start step ST502.
The selection of the next photodiode in this operation will be described later.

  When the monitor signal does not reach the predetermined level within time t1 in step ST505 for checking the level of the monitor signal VM, the process proceeds to step ST506 for determining whether or not the charge accumulation time reaches the limit time t3, and the accumulation stop due to saturation is performed. The determination and the monitor level check are repeated (steps ST506, ST504, ST505).

As described above, when charge accumulation due to saturation is stopped while the determination of accumulation stop due to saturation and the check level check are repeated, flag 1 (PEK When STP = 1) is set and the operation is the same as described above, and the monitor signal VM reaches a predetermined lens, flag 1 (MON) STP = 1) is set and the operation is the same as above.

If the charge accumulation is not stopped and the accumulation continues even after the limit time t3, flag 1 (LMT STP = 1) is set, and charge accumulation is stopped by the third accumulation stop means (steps ST506, ST513, ST508).
Thereafter, the process returns to step ST502 of sensor accumulation start through steps of stopping accumulation time count, 1 sensor data transfer, and next photodiode selection in the same manner as described above (steps ST509, ST510, ST511, ST502).

  As described above, flag 1 is caused by accumulation stop due to saturation (first accumulation stop means), accumulation stop due to level check of monitor signal VM (second accumulation stop means), and accumulation stop due to elapse of limit time (third accumulation stop means). Is set, and the photodiode for the next scan is selected according to the flag 1.

32 and 33 are flowcharts showing the photodiode selection operation.
As shown in these drawings, the charge accumulation is stopped by the first accumulation stop means, and PEK When flag 1 of STP = 1 is set, the flowchart of FIG. 33 is executed (step ST601).

  That is, when the accumulation stop of the first accumulation stop means is less than the time t1, it is when the brightness is high and the contrast is low. Therefore, in order to prioritize the accumulation time (Ctim), the photodiode is not switched and the current selection is performed. The next scan is performed with the photodiodes.

  In addition, when the accumulation stop of the first accumulation stop means exceeds the time t1, it is a case of medium brightness and low contrast. Therefore, in order to shorten the accumulation time, a photodiode having a pixel area larger by one rank is selected (step) ST703).

Specifically, when the previous readout scan is performed by the first photodiode line 300a, the second readout circuit is switched to read out the second photodiode line 300b.
Similarly, when the previous readout scan is performed on the second photodiode line 300b, or when performed on the first and second photodiode lines 300a and 300b, the first and second photodiodes are performed. It switches to the 3rd read-out circuit which adds and reads line 300a, 300b (step ST704).

When the accumulation stop of the first accumulation stop means exceeds the time t2, since it is in a low luminance and low contrast state, a photodiode having the maximum pixel area is selected in order to shorten the charge accumulation time.
That is, the first photodiode line 300a and 300b are added even if the previous scanning photodiode is the addition of the second photodiode lines 300a and 300b or the first photodiode lines 300a and 300b. Then, switching to the third readout circuit for readout is performed (steps ST701 and ST702).

On the other hand, the charge accumulation is stopped by the second accumulation stop means, and MON When flag 1 of STP = 1 is set, the flowchart of FIG. 32 is executed.
That is, when the accumulation stop of the second accumulation stop means is less than t1 time, since the signal component is sufficient with high contrast, a photodiode with a narrow pixel area is selected to improve the edge characteristics of the sensor output signal. (Steps ST605 and ST606).

  That is, if the photodiode that was scanned last time is the first photodiode line 300a or the second photodiode line 300b, the skewer switches to the first readout circuit that reads the first photodiode line 300a, and the previous scanning is the first one. When the operation is performed on the second photodiode lines 300a and 300b, the second photodiode circuit 300b is switched to a second readout circuit that reads out the second photodiode line 300b.

  When the charge stoppage of the second accumulation stop means is between t1 and t2, the control state is stable at medium contrast, so that the photodiode is not selected and the photodiode line readout circuit of the previous scan is maintained. The

  If the charge stoppage of the second storage stop means exceeds t2 time, a photodiode with a large pixel area is selected so as to shorten the storage time because it is in a low contrast state (steps ST603 and ST604).

  That is, when the previous scan is the first photodiode line 300a, the second photodiode line 300b is read out by the second readout circuit, and when the previous scan is the second photodiode / drain 300b, the first and second photodiodes are scanned. Switching to the third readout circuit that adds and reads the diode lines 300a and 300b, and if the third readout circuit is selected, the third readout circuit is maintained.

On the other hand, the charge accumulation is stopped by the third accumulation stop means, and the LMT When the flag 1 of STP = 1 is set, the photodiode is selected so that the pixel area is maximized in order to obtain the sensor output signal VO within the limit time t3 (steps ST602 and ST607).

That is, regardless of the photodiode line of the previous scan, the first and second photodiode lines 300a and 300b are always added and switched to the third readout circuit.
As described above, after the next scanning photodiode: line is selected, each flag is returned to 0 (step ST608).

  FIG. 34 summarizes the selection of the photodiodes described above.

According to the apparatus of FIG. 27, the focus detection sensor selectively operates the first, second, and third reading means according to the brightness of the subject and the contrast of the subject.
Accordingly, a photodiode line having a narrow pixel area or a photodiode line having a wide pixel area can be read, and further, a photodiode line having a narrow pixel area and a photodiode line having a wide pixel area can be added and read.
As a result, it is possible to obtain a highly accurate sensor output signal in which effective sensitivity is properly maintained and focus detection does not vary.
Further, according to the above-described focus detection apparatus, the first, second, and third reading means selectively operate according to the charge accumulation time of the focus detection sensor, so that the pixel area area that matches the brightness of the subject is obtained. , It is possible to obtain a focus detection signal having an effective sensitivity corresponding to a high S / N.
Furthermore, as described above, the focus adjustment unit of the photographing optical system is controlled by the focus detection device that selectively operates the first, second, and third reading units, so that an electronic imaging device having a highly accurate focus function is realized. can do.

It is a simplified diagram of a single-lens reflex camera provided with a focus detection device. It is an optical system figure of a focus detection apparatus. It is a simplified diagram of a line sensor shown as a conventional example. It is a simplified diagram of an area sensor shown as a conventional example. (A) shows a state in which an oblique subject is imaged on a rectangular pixel sensor, and (B) shows a sensor output signal in the imaged state in (A). (A) shows a state in which an oblique subject is imaged on a long rectangular pixel sensor, and (B) shows a sensor output signal in the imaged state in (A). (A) shows a state in which a subject is vertically imaged on a rectangular pixel sensor, and (B) is a diagram showing a sensor output signal in the image formation state in (A). (A) shows a state in which a subject is vertically imaged on a sensor having a long rectangular pixel, and (B) is a diagram showing a sensor output signal in the imaging state of (A). It is a figure which shows typically the electronic camera as an imaging device which employ | adopted the automatic focus detection apparatus which concerns on this invention. It is a figure which shows typically the image formation state by the re-imaging lens and focus detection sensor in the focus detection apparatus which concerns on this embodiment. It is a figure for demonstrating the principle which detects a phase difference. (A)-(C) are figures which show the light quantity distribution of the to-be-photographed image received by the A and A 'surface of FIG. It is a figure which shows the structural example of the focus detection area | region of the focus detection sensor surface of the focus detection apparatus which concerns on this embodiment. It is a figure which shows the example of arrangement | positioning of the focus detection area | region in the focus detection sensor of the focus detection apparatus which concerns on this embodiment. It is a figure which shows the specific structural example of the focus detection sensor of the focus detection apparatus which concerns on this embodiment. (A)-(C) are figures which show an example for extracting the contrast component about 1 block which divided | segmented the area sensor into 15 blocks. (A) and (B) are equivalent to the case of subtracting the minimum value in one block of 15 blocks that divide the area sensor in the process of subtracting the minimum value for extracting the contrast component, and the same as the minimum value level from the outside. It is a figure for demonstrating the example which supplies and subtracts an appropriate voltage to a sensor part. It is a figure which shows an example of the circuit block diagram of the controller which controls the focus detection apparatus (including a photoelectric conversion apparatus) and a focus detection apparatus which concern on this embodiment. It is a figure which illustrates each terminal of the photoelectric conversion apparatus in this embodiment, (A) is each terminal name, (B) is the input / output state with respect to the photoelectric conversion apparatus of the signal corresponding to each terminal, (C () Is a figure which shows the function of the signal corresponding to each terminal, respectively. In the photoelectric conversion apparatus of this embodiment, it is a figure which illustrates the change of each output signal with respect to accumulation time, (A) is a change of output signals S211 and S212 with respect to accumulation time, (B) is an output with respect to accumulation time. It is a figure which shows the change of signal S215, respectively. It is a timing chart for demonstrating operation | movement of the focus detection apparatus of FIG. It is a timing chart for demonstrating operation | movement of the focus detection apparatus of FIG. It is a timing chart for demonstrating operation | movement of the focus detection apparatus of FIG. It is a flowchart for demonstrating the outline | summary of operation | movement which concerns on this embodiment. It is a flowchart for demonstrating the accumulation | storage state monitoring operation | movement of the focus detection which concerns on this embodiment. It is a flowchart for demonstrating the accumulation | storage data output operation | movement of the focus detection which concerns on this embodiment. It is a figure which shows the other example of the circuit block diagram of the controller which controls the focus detection apparatus (a photoelectric conversion apparatus is included) and a focus detection apparatus which concern on this embodiment. FIG. 28 is a simplified diagram of an area sensor provided in the focus detection apparatus of FIG. 27. It is a characteristic view which shows the peak signal which the peak detection circuit with which the focus detection apparatus of FIG. 27 was equipped, and the bottom signal which a bottom detection circuit outputs. It is a characteristic view which shows the monitor signal which is a difference signal of a peak signal and a bottom signal. It is a flowchart which shows the charge accumulation control of the area sensor which the controller with which the focus detection apparatus of FIG. 27 was equipped performs. It is a flowchart which shows the photodiode selection operation | movement of the next scanning which the controller with which the focus detection apparatus of FIG. 27 was equipped performs. It is a flowchart which shows the photodiode selection operation | movement of the next scanning which the controller with which the focus detection apparatus of FIG. 27 was equipped performs. It is a figure which shows the selection aspect of the photodiode of the focus detection apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Electronic camera, 111 ... Optical system, 111 ... Imaging lens, 112 ... Quick turn mirror, 113 ... Focusing screen, 114 ... Pentaprism, 115 ... Submirror, 116 ... Reflection mirror, 117 ... Film surface, 120 ... Focus detection apparatus 122, re-imaging lens, 123, focus detection sensor, A, A ′, B, B ′, focus detection area (sensor surface), 130, controller. DESCRIPTION OF SYMBOLS 200 ... Area sensor, 200a, 200b ... Area sensor light-receiving surface, 202 ... Timing generator, 203 ... Serial interface, 204 ... Control signal interface, 210 ... Sensor signal processing part, 211 ... Maximum value detection part, 212 ... Minimum value detection part 213 ... Minimum value sample hold unit, 214 ... Maximum value comparison unit, 215 ... Maximum value / minimum value differential unit, 216 ... Sensor data / minimum value SH differential unit, 217 ... Sensor output / monitor output switching unit, 218 ... Amplifier, 130, 130A ... Controller, 131 ... CPU, 132 ... Memory, 120A ... Focus detection device, 300 ... Area sensor, 300a ... First photodiode line, 300b ... Second photodiode line, SW1, SW2, SW3 ... Switch element, AP ... Pixel amplifier, 301 ... P Detection circuit, 302 ... bottom detection circuit, 303 ... comparator, 304 ... timing generator, 305 ... op.

Claims (8)

An area sensor in which the light receiving unit is two-dimensionally arranged;
A dividing means for dividing the area sensor into a plurality of blocks;
Maximum value detecting means for detecting an exposure maximum value of each block divided by the dividing means;
Minimum value detecting means for detecting an exposure minimum value of each block divided by the dividing means;
External minimum value input means for inputting the external minimum value from the outside,
A selection means for selectively outputting an exposure minimum value output from the minimum value detection means and an external minimum value input from the external minimum value input means;
And a monitor output unit that generates a monitor signal from the maximum exposure value output from the maximum value detection unit and the minimum exposure value or the external minimum value output from the selection unit. Block selection means for designating at least one of a plurality of blocks divided by the dividing means;
The monitor output means sequentially outputs the monitor signal of each block for each block at a common output terminal. When a block is selected by the block selection means, the monitor signal of the selected block is output. The photoelectric conversion device according to claim 1, which outputs to a common output terminal as needed. The monitor output means outputs a monitor signal in order of each block read from the area sensor when a block is not designated by the block selection means, and a specific block is selected by the block selection means. In the case, the photoelectric conversion device according to claim 2, which interrupts in block order and outputs a monitor signal of a specific block to the common output terminal. The area sensor is a sensor having a pair of areas, and the maximum value detecting means, the minimum value detecting means, and the monitor output means are arranged in only one of the pair of area sensors. The photoelectric conversion apparatus as described in any one of these. The photoelectric conversion apparatus according to claim 4, further comprising means for controlling exposure amounts of both the pair of area sensors by a monitor signal from the monitor output means. An area sensor in which the light receiving unit is two-dimensionally arranged;
A dividing means for dividing the area sensor into a plurality of blocks;
Maximum value detecting means for detecting an exposure maximum value of each block divided by the dividing means;
Minimum value detecting means for detecting an exposure minimum value of each block divided by the dividing means;
External minimum value input means for inputting the external minimum value from the outside,
A selection means for selectively outputting an exposure minimum value output from the minimum value detection means and an external minimum value input from the external minimum value input means;
Monitor output means for generating a monitor signal from the exposure maximum value output from the maximum value detection means and the exposure minimum value or external minimum value output from the selection means;
Exposure amount detecting means for detecting that the exposure amounts of all the blocks are accumulated to a predetermined value or more by the monitor signal;
Instructing means for instructing reading of the accumulated data of the area sensor when it is detected by the exposure amount detecting means that all the blocks are accumulated more than a predetermined value;
Accumulated data output means for outputting accumulated data of the area sensor based on an instruction by the instruction means;
And a phase difference signal generating means for generating a phase difference signal from the accumulated data output by the accumulated data output means. An Eli sensor in which the light receiving part is arranged two-dimensionally;
A dividing means for dividing the area sensor into a plurality of blocks;
Maximum value detecting means for detecting an exposure maximum value of each block divided by the dividing means;
Minimum value detecting means for detecting an exposure minimum value of each block divided by the dividing means;
External minimum value input means for inputting the external minimum value from the outside,
A selection means for selectively outputting an exposure minimum value output from the minimum value detection means and an external minimum value input from the external minimum value input means;
Monitor output means for generating a monitor signal from the exposure maximum value output from the maximum value detection means and the exposure minimum value or external minimum value output from the selection means;
Exposure amount detecting means for detecting that the exposure amounts of all the blocks are accumulated to a predetermined value or more by the monitor signal;
Instructing means for instructing reading of the accumulated data of the area sensor when it is detected by the exposure amount detecting means that all the blocks are accumulated more than a predetermined value;
Accumulated data output means for outputting accumulated data of the area sensor based on an instruction by the instruction means;
Phase difference signal generating means for generating a phase difference signal from the accumulated data output by the accumulated data output means;
Focus control means for performing focus control by the phase difference signal output by the phase difference signal generation means;
And an optical lens controlled by the focus control means. A dividing step of dividing the area sensor in which the light receiving unit is two-dimensionally arranged into a plurality of blocks;
A maximum value detecting step for detecting a maximum exposure value of each of the divided blocks;
A minimum value detecting step for detecting a minimum exposure value of each of the divided blocks;
External minimum value input step for inputting external minimum value from outside,
A selection step for selectively outputting the detected exposure minimum value and the input external minimum value;
A monitor output step for generating a monitor signal from the detected exposure maximum value and the selected exposure minimum value or external minimum value;
An exposure amount detecting step for detecting that the exposure amounts of all the blocks are accumulated to a predetermined value or more by the monitor signal;
An instruction step for instructing reading of the accumulated data of the area sensor when it is detected in the exposure amount detection step that all the blocks have been accumulated over a predetermined value;
An accumulated data output step for outputting accumulated data of the area sensor based on the instruction;
And a phase difference signal generation step of generating a phase difference signal from the output accumulated data.

Images