JP2005148229A - Photoelectric convertor and automatic focus detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric convertor enabling automatic focus detection of space saving by having high accuracy at a high speed to a wide region, and to provide an automatic focus detector. <P>SOLUTION: On the basis of monitor output, in response to charge accumulation of an area sensor 100 when a sensor output/monitor output changeover part 116 selects the monitor output (output difference between the maximum value detection part 110 and the minimum value detection part 111) by a control signal from CPU 200, a controller 20 performs accumulation control; and when accumulation operation completes, the sensor output/monitor output changeover part 116 selects sensor output by the control signal from CPU 200. Then, a photoelectric conversion part 10 instructs a block region (sensor coordinates) of area sensor light receiving faces 100a and 100b by the controller 20 through serial communication, and the monitor output/sensor output are independently controlled with respect to each instructed block. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photoelectric conversion device and an automatic focus detection device that are used for automatic focus detection of, for example, a film camera, a digital 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.
8 and 9 are diagrams illustrating a configuration of a phase difference type focus detection device mounted on the imaging device.
As illustrated in FIG. 8, the imaging device includes a photographing lens 702, a mirror 703, an AF optical module 704, and a photographing photoelectric conversion element 705. As shown in FIG. 8, the luminous flux of the subject incident on the imaging apparatus is split into a luminous flux traveling to the AF optical module 704 and a luminous flux proceeding to the finder optical system by the mirror 703 after exiting the photographing lens 702.

FIG. 9 is a diagram illustrating an imaging state of a light beam traveling to the AF optical module in the focus detection apparatus described above.
As shown in FIG. 9, the AF optical module 704 includes a field mask 801, a condenser lens 802, a diaphragm mask 803, a pair of re-imaging lenses 804, and a photoelectric conversion element 805 for focus detection. The light beams 806a and 806b that have passed through a specific exit surface of the photographing lens 702 form an image on the photoelectric conversion element 805 as a pair of images.

Here, the image interval formed on the photoelectric conversion element 805 at the time of focusing is a predetermined image interval determined by the design of the AF optical module 704. When the focus is shifted to the front side with respect to the subject, in the case of the so-called front pin, the image interval is widened, and when the focus is shifted to the rear side with respect to the subject, in the case of the so-called rear pin, The image interval is narrowed.
Therefore, in the imaging apparatus with an AF function, the amount of defocus and the direction of displacement are calculated based on the difference between the image interval at the time of focusing determined by design and the image interval at the time of defocus (front pin or rear pin). The photographing lens 702 is driven by a built-in motor (not shown) so that the image interval becomes the image interval at the time of focusing determined by design.

The defocus amount is calculated using digital data obtained by A / D converting the output of the photoelectric conversion element by a CPU. In order to realize an automatic focus detection function capable of covering a wide range with high accuracy and high speed. Therefore, improvement of sensitivity and 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 for 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. The applicant discloses 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 signal of the maximum value and the minimum value incident on the sensor. Yes.

  That is, in the following Patent Document 1, the applicant of the present invention electrically detects the strongest partial light and electrically detects the weakest partial light among light incident on an image sensor such as a CCD image sensor. 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 in accordance with the difference between them is proposed.

  In the following Patent Document 2, the applicant of the present invention electrically detects the strongest partial light among the light incident on an image sensor such as a CCD image sensor, and electrically detects the weakest partial light. Has proposed a technology related to a charge accumulation time control device for an image sensor that regulates the charge accumulation time of the image sensor in accordance with the time until it reaches a predetermined level.

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

JP-A 64-85480 Japanese Patent Laid-Open No. 1-103077 JP-A-10-161014

  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.

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.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a photoelectric conversion device and an automatic focus detection device that can perform high-speed and high-precision automatic focus detection over a wide area and save space. Is to provide.

  In order to achieve the above object, a first aspect of the present invention includes a pair of area sensors in which light receiving units are two-dimensionally arranged, a division designation unit that designates the area sensor into a plurality of blocks, and the one pair. Maximum value detecting means for detecting an exposure maximum value of each divided block with respect to one area sensor of each of the area sensors, and each block divided with respect to one area sensor of the pair of area sensors And a monitor output means for generating a monitor signal based on the maximum exposure value and the minimum exposure value.

  In order to achieve the above object, a second aspect of the present invention includes a pair of area sensors in which a light receiving unit is two-dimensionally arranged, a division designation unit that designates the area sensor into a plurality of blocks, and the one pair. Maximum value detecting means for detecting an exposure maximum value of each divided block with respect to one area sensor of each of the area sensors, and each block divided with respect to one area sensor of the pair of area sensors A minimum value detecting means for detecting a minimum exposure value, a monitor output means for generating a monitor signal based on the maximum exposure value and the minimum exposure value, and a block selecting means for selecting a block. And the minimum value detecting means is arranged for each block, and outputs a monitor signal of the block selected by the block selecting means to an output stage common to each block. .

  Preferably, the sensor coordinates specified by the division specifying means are common coordinates in a pair of area sensors.

  In order to achieve the above object, a third aspect of the present invention includes a photographic lens that receives a light beam of a subject, a pair of area sensors in which a light receiving unit is two-dimensionally arranged and an image of the light beam of the subject is formed. A defocus amount is calculated based on the sensor outputs of the pair of area sensors, and the photographic lens is driven so that the defocus amount becomes zero. A division designation unit that designates division into blocks, a maximum value detection unit that detects an exposure maximum value of each divided block with respect to one area sensor of the pair of area sensors, and a pair of area sensors. A minimum value detecting means for detecting a minimum exposure value of each of the divided blocks, a monitor output means for generating a monitor signal based on the maximum exposure value and the minimum exposure value for one area sensor; In response to the monitor signal, accumulation of the sensor is terminated, a difference value between the sensor signal of the other area sensor of the pair of area sensors and the minimum exposure value is calculated, and the difference value is calculated as a sensor of the pair of area sensors. Sensor output means for output.

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.

Embodiments Hereinafter, embodiments of a photoelectric conversion device according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating an example of a circuit block diagram of a photoelectric conversion unit 10 and a controller 20 that controls the photoelectric conversion unit 10 that constitute the photoelectric conversion device according to the present embodiment.
As shown in FIG. 1, the photoelectric conversion unit 10 includes an area sensor 100 having a pair of light receiving surfaces 100a and 100b, a timing generator 102, a sensor signal processing unit 11, a serial interface (serial I / F) 103, And a control signal interface (control signal I / F) 104.
As will be described later, the area sensor 100 is divided into a plurality of blocks and is operable for each block. The photoelectric conversion unit 10 includes a sensor signal processing unit 11 for each block into which the area sensor 100 is divided.
The sensor signal processing unit 11 includes a maximum value detection unit 110 as a maximum value detection unit, a minimum value detection unit 111 as a minimum value detection unit, a minimum value sample hold unit 112, a maximum value comparison unit 113, and a maximum value. A minimum value differential unit 114, a sensor data / minimum value SH differential unit 115, a sensor output / monitor output switching unit 116 as a monitor output unit and a sensor signal output unit, and an amplifier 117. (Dotted line portion in FIG. 1).
The controller 20 includes a CPU 200 and a memory 201.
Hereinafter, the above-described components of the photoelectric conversion unit 10 and the controller 20 will be described.

The area sensor 100 is a part of a two-dimensionally arranged focus detection photoelectric conversion element such as a CCD, and includes a pair of area sensor light receiving surfaces 100a and 100b.
As described above, the area sensor 100 can operate in units of predetermined blocks, and the photoelectric conversion unit 10 is designated by the controller 20 through the serial interface 103 with respect to the coordinates of each block.

The timing generator 102 is a pulse generator that drives the area sensor 100 and generates a pulse corresponding to the frequency at which each function in the photoelectric conversion unit 10 operates.
The serial interface 103 includes an interface circuit for performing serial communication with the CPU 200 of the controller 20. The photoelectric conversion unit 10 performs an operation setting of the area sensor 100 based on each command transmitted from the CPU 200 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 100 from the CPU 200 and determining the area of each block. 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.
FIG. 2 is a diagram illustrating a state in which the area sensor 100 is divided into blocks, but as shown in FIG. 2A, the boundaries of the blocks may be in contact with each other, or FIG. As shown in FIG. 4, the boundaries of the blocks do not have to be in contact with each other.
(2) Block Coordinate Reading Command When the block of the area sensor 100 is designated from the CPU 200, it is a command that enables the coordinate value of the designated block to be read from the photoelectric conversion unit 10.
(3) Each Block Accumulation Status Reception Command When this command is transmitted from the CPU 200, it is possible to read information on whether or not each block of the area sensor 100 is currently accumulating charges.
As will be described later, when the output signal level of the maximum value detection unit 110 reaches a predetermined upper limit value, the photoelectric conversion unit 10 may automatically stop accumulation in units of blocks. This command is set so that the controller 20 can obtain information about whether the charge is accumulated or stopped.
(4) Sensor data output rate selection command By transmitting this command from the CPU 200, the data output rate of the area sensor 100 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 200 designates an arbitrary block of the area sensor 100 by this command, the photoelectric conversion unit 10 stops the charge accumulation of the designated block.
The CPU 200 that transmits this command corresponds to the storage end unit of the present invention.

The control signal interface 104 includes an input / output terminal through which the photoelectric conversion unit 10 exchanges control signals with the controller 20.
3A and 3B are diagrams showing input / output terminals (terminals) included in the control signal interface 104. FIG. 3A shows the names of the terminals, FIG. 3B shows the input / output of signals at the terminals, and FIG. 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. 3B, a signal at a terminal described as IN is a signal input from the controller 20, and a signal at a terminal described as OUT is a signal output to the controller 20.
In FIG. 3B, 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. 3A will be described.
The control signal CG is a control signal that instructs the controller 20 to start accumulation of the area sensor 100 (L level: accumulation start, H level: non-accumulation).
For example, when the CPU 200 of the controller 20 changes the CG terminal of the photoelectric conversion unit 10 from H level to L level, the photoelectric conversion unit 10 recognizes the level change via the control signal interface 104 and Charge accumulation is started for all blocks.
The CPU 200 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 photoelectric conversion unit 10 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 20 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 20 (L level: transfer start, H level: non-transfer). Usually, after the accumulation is completed, the transfer target block is specified and the transfer start is instructed at the timing when the transfer of the sensor data from the photoelectric conversion unit 10 is started.
The control signal TM is a control signal output from the photoelectric conversion unit 10 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 photoelectric conversion unit 10, and the CPU 200 of the controller 20 sequentially outputs sensor data in units of pixels output from the photoelectric conversion unit 10 in synchronization with the control signal AT. D-convert. Specifically, CPU 200 starts A / D conversion at the timing when control signal AT changes from H level to L level.
The control signal OM is a control signal instructed by the controller 20, and thereby, switching of sensor output or monitor output in the sensor output / monitor output switching unit 116 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 20, and instruct block selection for the signal VOUT (monitor output or sensor output) output from the amplifier 117. In this embodiment, since the output terminal for the signal VOUT is common to the sensor signal processing unit 11 corresponding to each block, the control signal AS1 to 4 is used to determine which block is output. 20 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. 3C).
The CPU 200 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 20, and mean the degree of amplification of sensor data or monitor data output from the amplifier 117.
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. 3C).
Note that the gain can be selected independently for each block by the control signals AGC0 to AGC2.

The maximum value detection unit 110 detects the maximum value of the output signal level of the light receiving unit 100b of the area sensor 100 as shown in FIG.
As shown in FIG. 1, the minimum value detection unit 111 detects the minimum value of the output signal level of the light receiving unit 100 b of the area sensor 100.
The maximum value detection unit 110 and the minimum value detection unit 111 may detect the signal output of one of the pair of light receiving units 100a and 100b of the area sensor 100. This is because, as shown in FIG. 8, since the same image is formed on each surface of the pair of area sensor light receiving units 100a and 100b by the re-imaging lens, only one surface needs to be monitored. . In the present embodiment, as shown in FIG. 1, the area sensor light receiving surface 100b is monitored.

  The minimum value sample hold unit 112 samples and holds the output signal S111 of the minimum value detection unit 111 in synchronization with the signal of the predetermined frequency generated by the timing generator 102 (sample hold).

The maximum value comparison unit 113 compares the output signal S110 of the maximum value detection unit 110 with a predetermined saturation level (stop level) in order to avoid saturation of accumulation in the area sensor 100, and the output signal S110 has a saturation level. If it exceeds, that is, if it is determined that the charge accumulation of the area sensor 100 has reached the saturation level, the output signal S113 is set to the L level.
The sensor signal processing unit 11 is provided for each block, and the maximum value comparison unit 113 of the sensor signal processing unit 11 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 photoelectric conversion unit 10 stops the charge accumulation without waiting for the “accumulation stop command” from the controller 20 for the block in which the output signal S113 of the corresponding maximum value comparison unit 113 has changed from the H level to the L level. .
The reason why the accumulation is automatically stopped on the photoelectric conversion unit 10 side when the saturation level is reached is because a delay in accumulation control of the controller 20 based on a monitor output (VOUT) described later is taken into consideration.
That is, the controller 20 controls accumulation based on a monitor output (signal S114), which will be 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 if a delay occurs in the control, in order to avoid saturation of accumulation in the sensor, as described above, when the saturation level is reached, the accumulation operation is automatically stopped on the photoelectric conversion unit 10 side. I have decided.

The maximum value / minimum value differential unit 114 outputs a monitor output (signal S114) obtained by subtracting the output signal of the maximum value detection unit 110 and the output signal of the minimum value detection unit 111 via the sensor output / monitor output switching unit 116. , And supplied to the amplifier 117.
FIG. 4 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 S110 and S111 with the passage of time, and (b) shows the output. Changes in the signal level of the signal S114 (monitor output) with time are shown.
As shown in FIG. 4, since the exposure amount increases as the charge accumulation time elapses, both the output signal S110 of the maximum value detection unit 110 and the output signal S111 of the minimum value detection unit 111 increase (FIG. 4 (a )). A monitor output S114 obtained by calculating a difference value from these output signals S110 and S111 is output as shown in FIG.

  The sensor data / minimum value SH differential unit 115 calculates and outputs a difference value between the sensor output of the area sensor light receiving surface 100a and the output signal S111 of the minimum value detection unit 111 sampled and held by the minimum value sample hold unit 112. (Signal S115).

The sensor output / monitor output switching unit 116 is either the output signal S114 (monitor output) of the maximum / minimum value differential unit 114 or the output signal S115 (sensor output) of the sensor data / minimum value SH differential unit 115. It has a switch function that enables signal selection.
The signal selection can be switched by a control signal OM (OM signal) supplied from the controller 20, 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 117 outputs the signal (monitor output or sensor output) selected by the sensor output / monitor output switching unit 116 based on the amplification degree (gain) specified by the control signals AGC0 to AGC to the A / D of the CPU 200 of the controller 20. Output to the conversion unit (signal VOUT).
As described above, when the OM signal that is a control signal from the controller 20 is at the L level, the sensor output / monitor output switching unit 116 selects the monitor output, and the amplifier 117 amplifies and outputs the monitor output.
In that case, if the output terminals are arranged for each block, the number of terminals becomes enormous, resulting in an increase in the size of the photoelectric conversion unit 10 and variations in the output signals 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 20 includes a CPU 200 and a memory 201.
The CPU 200 transmits a control signal to each terminal of the photoelectric conversion unit 10 and controls charge accumulation of the photoelectric conversion unit 10 of the photoelectric conversion unit 10. Furthermore, the CPU 200 performs serial communication with the photoelectric conversion unit 10 and sets the accumulation operation in the area sensor 100.
Further, when the area sensor 100 of the photoelectric conversion unit 10 is accumulating charges, the CPU 200 controls the charge accumulation by inputting the monitor output of each block as VOUT. That is, the CPU 200 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 The designated accumulation stop command is sent to the photoelectric conversion unit 10.

Further, the CPU 200 performs gain setting corresponding to the accumulation time and the monitor output for each block, and stores the gain setting in the memory 201.
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 100, the sensor output is input as VOUT, and the input sensor output is converted to digital using the control signal AD from the photoelectric conversion unit 10 as a trigger and processed. At that time, the gain for each block stored in the memory 201 is read and applied.

  The memory 201 includes a nonvolatile memory such as an EEPROM, and stores the gain setting value of the amplifier 117 of the photoelectric conversion unit 10 for each block of the area sensor 100.

In the above, each component of the photoelectric conversion part 10 and the controller 20 was demonstrated.
Next, the operation of the photoelectric conversion apparatus according to this embodiment will be described with reference to the timing charts of FIGS.
5, FIG. 6 and FIG. 7 are timing charts for explaining the operation of the photoelectric conversion device in this embodiment. FIG. 5, (A) shows the startup state of the power supply of the photoelectric conversion unit 10, and (B) shows the reset ( (RST) signal (L: active), (C) master clock (MCLK) signal, (D) communication state performed by the serial interface 103, (E) control signal CG, and (F) control signal CH. (G) is an accumulation state of each block of the area sensor 100, (H) is an output signal VOUT (monitor output / sensor output), (I) is a control signal OM, (J) is a control signal AS1. 4, (K) indicates the control signals AGC 0 to 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. 5 to FIG.

  As shown in FIG. 5A, when the power source of the photoelectric conversion unit 10 is activated at time t0, the reset signal soon becomes H level (FIG. 5B), and the master clock having a predetermined frequency operates. By doing (FIG. 5D), each function of the photoelectric conversion unit 10 becomes operable. First, as illustrated in FIG. 5D, the controller 20 performs initial setting of the photoelectric conversion unit 10 by serial communication via the serial interface 103.

  As an initial setting, for example, block designation for the area sensor 100 is performed by a block coordinate designation command. As described above, the area sensor 100 can operate for each designated block. In this description, as shown in FIG. 2A, it is assumed that the blocks are divided into 15 blocks so that the divided areas of the blocks are in contact with each other.

In FIG. 6, at time t <b> 1, the CPU 200 of the controller 20 instructs the photoelectric conversion unit 10 to accumulate charges. That is, the CPU 200 changes the control signal CG from the H level to the L level as shown in FIG.
Thereby, the photoelectric conversion unit 10 starts the charge accumulation of all the blocks of the area sensor 100 all at once, and accordingly, as shown in FIG. 6G, each of the blocks BLK1 to 15 of the area sensor 100. The block is in charge accumulation (H level) after time t1.
Further, as shown in FIG. 6F, 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 blocks. Since the value is output, the control signal CH becomes H level soon after time t1.

The accumulation amount monitor signal (monitor output) VOUT shown in FIG. 6H is a maximum value (signal S110) which is a signal output by the maximum value detection unit 110 and the minimum value detection unit 111 provided for each block. , The difference value of the minimum value (signal S111) is calculated by the maximum value / minimum value differential unit 114 and output.
At this time, blocks of a predetermined area sensor 100 are designated by control signals AS1 to AS4 (FIG. 6 (J)) transmitted from the controller 20, and control signals AGC0 to AGC2 to 2 (FIG. 6 (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 20, and the accumulation level (accumulation amount) is determined in the CPU 20. 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. .

In FIG. 6, at time t2, as shown in FIG. 6G, the second block (BLK2) of the area sensor 100 automatically stops accumulation (maximum value automatic stop) in order to avoid accumulation saturation. ) And the accumulation state is turned off (L level).
That is, the output signal S110 of the maximum value detection unit 110 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 113, When the output signal S110 exceeds the saturation level, that is, when it is determined that the charge accumulation of the area sensor 100 has reached the saturation level, the output signal S113 is set to the H level.
Thereby, the photoelectric conversion unit 10 stops the accumulation of the area sensor 100 only in the second block (BLK2).

During the charge accumulation, when the CPU 200 of the controller 20 transmits the “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 photoelectric conversion unit 10 monitors the output signal S113 of the maximum value comparison unit 113 of the sensor signal processing unit 11 corresponding to each block, and determines whether or not each block is accumulating (accumulation state). The result is returned to the controller 20 by serial communication (“Accumulation status reception” in FIG. 6D).
As described above, when the photoelectric conversion unit 10 stops the accumulation of only the second block (BLK2), the controller 20 responds to the “each block accumulation status reception command” in response to the second block (BLK2). ) Accumulation can be recognized.

In FIG. 6, at time t <b> 3, the CPU 200 determines that the accumulation level (accumulation amount) is sufficient when the monitor output VOUT for successive A / D conversion reaches a predetermined level, and the photoelectric conversion unit 10 An “accumulation stop command” is transmitted (“accumulation stop” in FIG. 6D).
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. 6, 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 200 of the controller 20 sends out an “accumulation stop command” designating all blocks by serial communication, and the photoelectric conversion unit 10 that has received the “accumulation stop command” thereafter stops accumulating all blocks.
Further, as shown in FIG. 6F, when the accumulation of all the blocks is stopped and the accumulation state is turned off (BLK 1 to 15 in FIG. 6G are all at L level), the signal of the accumulation state of each block Since the control signal CH indicating the OR logic value of the signal changes from the H level to the L level (FIG. 6F), the controller 20 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 100 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 116 of the photoelectric conversion unit 10.
Therefore, as shown in FIG. 6I, the CPU 200 of the controller 20 changes the control signal OM from the L level to the H level at time t4.
Thereby, in the photoelectric conversion unit 10, the sensor output / monitor output switching unit 116 switches from the monitor signal (monitor output) to the sensor signal (sensor output), and the sensor data / minimum value SH differential unit 115 The output signal S115, that is, the difference value between the sampled and held minimum value signal (S112) and the sensor signal is amplified by the amplifier 117 and output as VOUT (FIG. 6H).

At that time, first, the controller 20 transmits a “sensor data output rate selection command” to the photoelectric conversion unit 10 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.
Moreover, the controller 20 designates the block to be output to the photoelectric conversion unit 10 by the control signals AS1 to AS4.

Then, the controller 20 designates the gain at the end of accumulation stored in the memory 202 as the gain of the amplifier 117 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. 6 (L), when the controller 20 sets the control signal TH to the L level at time t5, the photoelectric conversion unit 10 outputs sensor data output (sensors) of the block designated by the control signals AS1 to AS4. Output).
At that time, as shown in FIG. 6 (N), in synchronization with the control signal AT output from the photoelectric conversion unit 10 side, the CPU 200 of the controller 20 takes in the output for each pixel and performs A / D conversion. . That is, at the timing when the control signal AT having the pulse waveform shown in FIG. 6N is switched from the L level to the H level, the pixel signal output from the photoelectric conversion unit 10 is switched, 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 200 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. 6, as shown in FIG. 6 (J), the first block (BLK1) is first selected, its sensor data is taken in, and A / D conversion is performed.

After time t5, as shown in FIG. 7, the respective blocks are sequentially selected by the controller 20, and the sensor data VOUT of each block of the photoelectric conversion unit 10 is taken into the controller 20 and A / D conversion is performed.
In FIG. 7, as shown in (J), blocks 6 and 7 are designated, and sensor data VOUT of each block is taken into the controller 20 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 20 can return the control signal TH from the L level to the H level to stop the data output at that time. In other words, after extracting the necessary data from the sensor output of each block, the controller 20 stops the data transfer so that the next process can be performed immediately after the unnecessary data transfer is aborted. (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. 7D, in order to speed up the data transfer process, the controller 20 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 for data other than the necessary part, and the transfer rate is reduced to the speed at which the CPU 200 can perform A / D conversion for the necessary part of 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.

As described above, according to the photoelectric conversion device of this embodiment, the pair of light receiving surfaces 100a and 100b and the pair of area sensor light receiving surfaces 100a and 100b of the area sensor 100 on which the same image is formed, respectively. A maximum value detecting unit 110 for obtaining the maximum value of one of the outputs, a minimum value detecting unit 111 for obtaining the minimum value, and a maximum / minimum value differential unit for calculating a difference value (monitor output) between the maximum value and the minimum value. 114, a minimum value sample hold unit 112 that samples and holds the minimum value output from the minimum value detection unit 111, a minimum value sampled and held by the minimum value sample hold unit 112, and a pair of area sensor light receiving surfaces 100a and 100b. Sensor data / minimum value SH differential unit 115 for calculating a difference value (sensor output) from the other output, and either monitor output or sensor output The sensor output / monitor output switching unit 116 to be selected and output, the amplifier 117 that amplifies and outputs the monitor output or the sensor output, the serial interface 103 that performs serial communication with the external controller 20 including the CPU 200, and the control from the CPU 200. When the photoelectric conversion unit 10 has a control signal interface 104 that receives a signal and a monitor output is selected by a control signal from the CPU 200, the controller 20 accumulates by the monitor output corresponding to the charge accumulation of the area sensor 100. When the accumulation operation is completed, the accumulation operation is stopped, and at the same time, the sensor output is selected and processed by a control signal from the CPU 200.
At that time, the photoelectric conversion unit 10 designates block areas (sensor coordinates) of the area sensor light receiving surfaces 100a and 100b by the controller 20 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 according to the present embodiment, the maximum value detection unit 110 and the minimum value detection unit 111 are set to either one of the pair of light receiving surfaces 100a and 100b of the area sensor 100 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 110 and the minimum value detection unit 111 are arranged for each block and share a monitor output terminal for each block. Therefore, as compared with the case where each block has a monitor output terminal. The variation in the output circuit characteristics between the blocks can be reduced, and the photoelectric conversion unit 10 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 100a, 100b, 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 photoelectric conversion device of this embodiment starts accumulation of the area sensor 100 by a control signal (control signal CG) from the controller 20, receives a command (accumulation stop command) from the controller 20, and accumulates the area sensor 100. When the storage 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 optimal control for each block of the area sensor 100. is there. 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 device of this embodiment, the gain of the amplifier 117 corresponding to the accumulation time and the monitor output is set for each block by the controller 20, 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.

As shown in FIGS. 8 and 9, the photoelectric conversion device of this embodiment can be applied to an automatic focus detection device of a camera with an AF function (imaging device).
In such a case, as described above, the photoelectric conversion device of the present embodiment can obtain a photoelectric conversion output with high accuracy and high speed in a wide area, calculate the defocus amount based on the obtained photoelectric conversion output, Since the photographic lens is driven so that the amount of defocus is zero, high-speed and high-precision focus detection can be performed.

It is a figure which shows one example of the circuit block diagram of the photoelectric conversion apparatus in this embodiment. It is a figure which illustrates the aspect divided | segmented by the block of an area sensor light-receiving surface, (a) shows the aspect which the boundary of each block touches, (b) shows the aspect which the boundary of each block does not touch, respectively. 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 ) Indicates the function of the signal corresponding to each terminal. 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 signal S110,111 with respect to accumulation time, (b) is an output with respect to accumulation time. Changes in the signal S114 are shown respectively. 6 is a timing chart for explaining the operation of the photoelectric conversion device according to the present embodiment. 6 is a timing chart for explaining the operation of the photoelectric conversion device according to the present embodiment. 6 is a timing chart for explaining the operation of the photoelectric conversion device according to the present embodiment. It is the figure which illustrated progress of subject light in an imaging device. It is the figure which illustrated the image formation state of AF optical module of a focus detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Photoelectric conversion part 100 ... Area sensor 100a, 100b ... Area sensor light-receiving surface 102 ... Timing generator 103 ... Serial interface 104 ... Control signal interface 11 ... Sensor signal processing part 110 ... Maximum value detection part 111 ... Minimum value detection part 112 ... Minimum value sample hold unit 113 ... Maximum value comparison unit 114 ... Maximum value / minimum value differential unit 115 ... Sensor data / minimum value SH differential unit 116 ... Sensor output / monitor output switching unit 117 ... Amplifier 20 ... Controller 200 ... CPU
DESCRIPTION OF SYMBOLS 201 ... Memory 702 ... Shooting lens 703 ... Mirror 704 ... AF optical module 801 ... Field mask 802 ... Condenser lens 803 ... Aperture mask 804 ... A pair of re-imaging lens 804a, 804b ... Re-imaging lens 805 ... Photoelectric conversion element 705 ... Photoelectric conversion element for photography

Claims (10)

A pair of area sensors in which the light receiving portions are two-dimensionally arranged;
A division designation means for dividing the area sensor into a plurality of blocks;
Maximum value detecting means for detecting an exposure maximum value of each divided block with respect to one area sensor of the pair of area sensors;
Minimum value detecting means for detecting an exposure minimum value of each divided block with respect to one area sensor of the pair of area sensors;
And a monitor output means for generating a monitor signal based on the maximum exposure value and the minimum exposure value. A pair of area sensors in which the light receiving portions are two-dimensionally arranged;
A division designation means for dividing the area sensor into a plurality of blocks;
Maximum value detecting means for detecting an exposure maximum value of each divided block with respect to one area sensor of the pair of area sensors;
Minimum value detecting means for detecting an exposure minimum value of each divided block with respect to one area sensor of the pair of area sensors;
Monitor output means for generating a monitor signal based on the maximum exposure value and the minimum exposure value;
Block selection means for selecting a block, and
The maximum value detection means and the minimum value detection means are arranged for each block, and output a monitor signal of the block selected by the block selection means to an output stage common to each block. . The photoelectric conversion apparatus according to claim 1, wherein the sensor coordinates designated by the division designation unit are common coordinates in a pair of area sensors. Accumulation start means for starting accumulation of area sensors;
Accumulation end means for ending accumulation of the area sensor;
Sensor signal output means for outputting a sensor signal after the accumulation,
Block selection means for selecting a block, and
2. The photoelectric device according to claim 1, wherein the block selection unit acts on two or more units among the accumulation start unit, the accumulation end unit, the monitor output unit, and the sensor signal output unit. Conversion device. Accumulation start means for starting accumulation of area sensors;
Accumulation end means for ending accumulation of the area sensor;
Sensor signal output means for outputting a sensor signal after the accumulation,
Further comprising
3. The photoelectric device according to claim 2, wherein the block selection unit acts on two or more units among the accumulation start unit, the accumulation end unit, the monitor output unit, and the sensor signal output unit. Conversion device. An imaging lens for receiving the luminous flux of the subject, a light receiving unit arranged two-dimensionally, a pair of area sensors on which the luminous flux of the subject is imaged, and a defocus amount based on the sensor output of the pair of area sensors And an automatic focus detection device for driving the photographing lens so that the amount of defocus is zero,
Division designation means for dividing and designating the area sensor into a plurality of blocks;
Maximum value detecting means for detecting an exposure maximum value of each divided block with respect to one area sensor of the pair of area sensors;
Minimum value detecting means for detecting an exposure minimum value of each divided block with respect to one area sensor of the pair of area sensors;
Monitor output means for generating a monitor signal based on the maximum exposure value and the minimum exposure value;
In response to the monitor signal, accumulation of the sensor is terminated, a difference value between the sensor signal of the other area sensor of the pair of area sensors and the minimum exposure value is calculated, and the difference value is calculated by the pair of area sensors. An automatic focus detection apparatus comprising: sensor output means for outputting a sensor. An imaging lens for receiving the luminous flux of the subject, a light receiving unit arranged two-dimensionally, a pair of area sensors on which the luminous flux of the subject is imaged, and a defocus amount based on the sensor output of the pair of area sensors And an automatic focus detection device for driving the photographing lens so that the amount of defocus is zero,
Division designation means for dividing and designating the area sensor into a plurality of blocks;
Maximum value detecting means for detecting an exposure maximum value of each divided block with respect to one area sensor of the pair of area sensors;
Minimum value detecting means for detecting an exposure minimum value of each divided block with respect to one area sensor of the pair of area sensors;
Monitor output means for generating a monitor signal based on the maximum exposure value and the minimum exposure value;
In response to the monitor signal, accumulation of the sensor is terminated, a difference value between the sensor signal of the other area sensor of the pair of area sensors and the minimum exposure value is calculated, and the difference value is calculated by the pair of area sensors. Sensor output means for sensor output;
Block selection means for selecting a block, and
The maximum value detection means and the minimum value detection means are arranged for each block, and output a monitor signal of the block selected by the block selection means to an output stage common to each block. apparatus. The automatic focus detection apparatus according to claim 6 or 7, wherein the sensor coordinates designated by the division designation means are common coordinates in a pair of area sensors. Accumulation start means for starting accumulation of area sensors;
Accumulation end means for ending accumulation of the area sensor;
Block selection means for selecting a block, and
The automatic focus detection apparatus according to claim 6, wherein the block selection unit acts on two or more units among the accumulation start unit, the accumulation end unit, and the monitor output unit. Accumulation start means for starting accumulation of area sensors;
Accumulation end means for ending accumulation of the area sensor;
Further comprising
The automatic focus detection apparatus according to claim 7, wherein the block selection unit acts on two or more units among the accumulation start unit, the accumulation end unit, and the monitor output unit.

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