JP2000078483A - Solid-state image pickup device and automatic aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high speed setting of an exposing condition when the exposing condition is set before photographing by reading a part of a block, saving photoelectric charges stored during storage time and transferring the photoelectric charges to be obtained by new storage by cumulating and adding them. SOLUTION: First reading of the block is performed by setting the exposing condition for a photoelectric conversion device panel 11. The photoelectric charges of a pixel element in the block are integrated and a first integrated value is inputted in a judging circuit 13. Then, second reading of the block is performed, for example, by changing shutter speed as low, the photoelectric charges of the pixel element in the block are integrated and a second integrated value is inputted in the judging circuit 13. Then, third reading of the block is further performed, the photoelectric charges of the pixel element in the block are integrated and a third integrated value is inputted in the judging circuit 13. When an integration result reaches an AE(Automatic Exposure) target value, the exposing condition in main photographing is outputted by the judging circuit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device having a photoelectric conversion device, and more particularly to a solid-state imaging device and an automatic exposure device which can optimally set exposure conditions for a digital camera or the like.

[0002]

2. Description of the Related Art In recent years, in an image pickup apparatus, a video camera, and the like, a reduction in the cell size of a photoelectric conversion element using a miniaturization process has been energetically performed for high resolution. on the other hand,
2. Description of the Related Art An amplification type photoelectric conversion device capable of amplifying and outputting a photoelectric conversion signal has been attracting attention because the output of the photoelectric conversion signal is reduced. As such an amplification type photoelectric conversion device, there is a two-dimensional solid-state imaging device of an XY address type sensor such as BASIS, MOS type, SIT, AMI, and CMD.
On the other hand, as a two-dimensional solid-state imaging device, higher density and higher S / N
Therefore, a CCD (Charge Coupled Device) type sensor is excellently used.

Further, in a digital camera or the like having a two-dimensional solid-state imaging device, an exposure condition for the imaging is appropriately adjusted at the time of imaging to set an exposure time according to the sensitivity of the solid-state imaging device. At the time of setting the exposure time, the amount of light hitting a part of the two-dimensional area sensor is measured, and parameters such as an aperture are shaken until the value reaches a certain target value.
Finding the optimal value. This operation is called AE (Automatic Ex
posure).

In the case of an AE of a digital camera, a CCD type 2
The dimensional area sensor reads out all pixel data, extracts blocks from them, accumulates them once, compares them with an appropriate predetermined exposure level, changes parameters such as shutter speed and aperture, and extracts blocks again. Then, a condition when the exposure level reaches the predetermined exposure level is determined as an exposure condition by repeating the operation several times.

FIG. 7 is a schematic block diagram of an AE system using a solid-state imaging device using a CCD panel. CCD
The panel 61 converts an image signal read out in time series into an A / A signal regardless of the interline transfer method or the frame transfer method.
The digital image signal is converted into a digital image signal by the D converter 62 and is written into the frame memory 63 for one frame. For AE, in particular, only the central block is read out, the image signal level of the block area is integrated by the integrator 64, and the total integrated value of the block area is obtained. The total integration value is compared with a predetermined exposure level in a determination circuit 65, and if there is a difference in the comparison result, the result is output to an exposure condition setting circuit 66. The exposure conditions refer to the exposure time / shutter time and aperture degree of the CCD panel, the accumulation time of the CCD panel, etc., and change the shutter time and the like. The CCD panel is operated again according to the setting of the exposure condition setting circuit 66, and the exposure integrated value of the predetermined block area is detected, and the judgment circuit 65 makes a comparison and judgment to obtain an optimum exposure value.

In this AE system, as shown in the timing chart of FIG. 7B, when the exposure time indicated by the low level is accumulated (1), the reading of a predetermined block area from the frame memory 63 after the accumulation is integrated. AE evaluation (2) indicating the time as a high level, and AE value (3) at each AE evaluation
The predetermined AE value is indicated by a dotted line in (3). If this is shown in a graph, it becomes FIG.
Since the AE value is too high in the first exposure detection value and exceeds the saturation level of the CCD panel, the fourth exposure AE
The optimum AE can be executed by setting the exposure condition at the time of the value to the condition for the AE.

[0007]

However, CCDs
In the solid-state imaging device, it is impossible to read out blocks necessary for AE, and a specific block must be read out after one frame of image signal is stored in the frame memory once. In this case, A / D conversion time, frame storage time, and block read time are required, it takes time to set exposure conditions for AE, and the layout area of the frame memory is large, so that miniaturization cannot be achieved.

Accordingly, an object of the present invention is to provide a method suitable for an AE for a digital camera or the like in order to solve the above-mentioned problems.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned object, and it is an object of the present invention to provide a two-dimensionally arranged solid-state imaging device for converting optical information into photocharges to obtain an output signal. Block reading means for reading a partial block of the imaging device, holding means for storing the photocharges accumulated during the accumulation time, and transfer means for transferring the photocharges newly obtained by accumulation to the holding means and accumulatively adding the photocharges It is characterized by.

Further, according to the present invention, in a solid-state image pickup device for picking up an image using an area sensor in which a plurality of photoelectric conversion elements are arranged, the area is divided into a plurality of blocks in the area of the area sensor, and the photoelectric charge of each block is read out. It is characterized by comprising a block reading means, and integrating means for integrating a photoelectric charge signal of each of the block reading means for each photoelectric conversion element in each of the blocks.

Further, the present invention relates to an automatic exposure apparatus using an area sensor having a plurality of photoelectric conversion means arranged therein, wherein the block reading means for reading out the photoelectric charges of the photoelectric conversion means of the blocks in the area sensor; And a determination circuit for comparing and determining the integration result of the integration means with a predetermined exposure level.

[0012]

[First Embodiment] FIG. 1 is a schematic block diagram of a first embodiment according to the present invention. The solid-state imaging device according to the present embodiment has an AE function and includes a CMOS sensor.

In FIG. 1, reference numeral 11 denotes a so-called CMOS sensor, which is manufactured by a CMOS process technology.
It is a chip sensor, and has a horizontal scanning circuit and a vertical scanning circuit for reading out the sensor.
Block reading in the CMOS sensor is enabled.
Numeral 12 denotes an integrating circuit for integrating the photoelectric charge of each pixel element for the block reading, and 13 a judging circuit for comparing and judging the integration result of the integrating circuit with a predetermined exposure level.
Reference numeral 4 denotes an exposure condition setting means for setting an exposure condition, for example, a shutter speed, an aperture, an accumulation time in a CMOS pixel, etc., in accordance with a result of the judgment by the judgment circuit. A CPU that calculates and detects conditions and controls the AE function and the solid-state imaging device.

Next, the AE function will be described with reference to the timing chart shown in FIG. First, C
The exposure condition is set for the MOS sensor 11, the first block reading is performed, the photocharges of the pixel elements in the block are integrated, and the integration result is input to the determination circuit 13 as the first integration value. . Subsequently, for example, the shutter speed of the exposure condition setting means is changed to a low shutter speed, and the second block reading is performed, and the photocharges further accumulated in the pixel elements in the block are integrated, and the integration result is used as a second integration value. It is input to the judgment circuit 13. Subsequently, a third block read is performed by changing the shutter speed of the exposure condition setting means, for example, to a slower speed, and the photocharges further accumulated in the pixel elements in the block are integrated. The value is input to the determination circuit 13. When the integration result reaches the AE target value, the determination circuit 13 outputs the exposure condition at that time as the exposure condition for the main photographing.

According to the above timing chart, the integrated value is obtained a plurality of times by changing the exposure condition until the AE target value is reached. However, the integrated value can be obtained quickly by utilizing the calculation function of the CPU 15. That is, the exposure condition is, for example, shutter speed tsec / 1, and at the first shutter speed t1, the integration result by exposure is a1, and from the result, the target value an is reached at the second shutter speed t2. In this case, the shutter speed tn becomes tn =
Based on the calculation result of t1 + t2, the optimum exposure condition can be obtained by repeating the exposure condition twice.

[Embodiment 2] FIG. 2 is a schematic block diagram of a second embodiment according to the present invention. In this AE device, C
Five partial block regions in the MOS area sensor are specified, and the photocharges of the pixel elements are read from the partial block regions, respectively integrated by the integration circuits 22a to 22e, and the integration result is input to the determination circuit 23. The exposure level is compared with the predetermined exposure level for each partial block area. If the exposure level does not reach the predetermined exposure level, the exposure conditions are changed by the exposure condition setting circuit 24, and the reading and integration of each partial block area are repeated again. If you get the exposure level,
The exposure condition at that time is output as the optimal exposure condition.

As described above, by performing photometry by dividing the imaging surface into multiple parts, photometry is performed not on the central portion but on the entire imaging surface, so that an optimum exposure condition for an image different from the central photometry can be set.

[Embodiment 3] FIG. 3 is a schematic block diagram of an AE system according to a third embodiment of the present invention. In the figure, reference numeral 31 denotes a CMOS area sensor, which uses a scanning method in which the data is read out by dividing into 16 blocks as a reading method. Reference numerals 32a to 32p denote average value circuits for averaging the photocharges of the 16 divided blocks. For example, if one block is 160 × 120 pixels, the average value circuit is obtained by the integral value of all pixels / (160 × 120). A determination circuit 33 compares and determines the average value output of each of the average value circuits 32a to 32p with a predetermined AE target value level, and sets an exposure condition when the target value matches the target value as an optimum exposure condition. If it does not match the target value, the exposure condition setting circuit 34
The exposure condition is changed and the average value of the 16-divided block of the CMOS sensor is obtained again, and the determination circuit 33 compares and determines the average value with the target value.

Further, the target value may be one or 16 target values corresponding to each block. In the case where there is one target value, when there is an area with a large amount of light even in one place of the object, an exposure condition suitable for the area can be set. When the target value is 16, the condition when any one of the average values of the blocks reaches the target value is set as the optimal exposure condition. An inconspicuous and uniform image signal can be obtained.

[Embodiment 4] In the present embodiment, the first
An embodiment of block reading used in the third embodiment will be described.

FIG. 4 shows a configuration diagram of a CMOS area sensor used in the first and third embodiments of the present invention. FIG. 4 is a configuration diagram of a two-dimensional sensor having 2 × 2 pixels, but the number of pixels is not limited to this. The pixel configuration of the solid-state imaging device in FIG. 4 will be described. A photodiode 90 is provided in the pixel.
1, a transfer switch 911, a reset switch 902, a pixel amplifier 903, and a row selection switch 904 are provided.
They are connected as shown in FIG. The photoelectric conversion is performed by the photodiode 901. During the accumulation period, the transfer switch 911 is in an off state, and the gate of the source follower 903 that constitutes the pixel amplifier is charged with the charge photoelectrically converted by the photodiode 901. Not transferred. The reset switch 902 is turned on before the accumulation of the gate of the source follower 903 constituting the pixel amplifier, and is initialized to an appropriate voltage. That is, this is the dark level.

Next, when the row selection switch 904 is turned on, the source / follower circuit composed of the load current source 905 and the pixel amplifier 903 is operated, and the transfer switch 911 is turned on. Then, the charges accumulated in the photodiode 901 are transferred to the gate of the source follower 903 constituting the pixel amplifier. Here, the output of the selected row is generated on the vertical output line 906. This output is stored in the signal storage unit 907 via the transfer gates 909a and 909b. Signal storage unit 907
Are temporarily read out to the output unit by the horizontal scanning circuit 908.

FIG. 5 shows a conceptual diagram of a reading method of the solid-state imaging device as the area sensor. FIG. 5 (a)
Is an example of all-pixel reading, in which a reference signal output photoelectric conversion element group shields two pixels on the left side of the drawing from light and detects a reference signal voltage of dark charges generated in the pixel. In addition, as an effective signal output photoelectric conversion element, an effective signal voltage of photoelectric charges in a range in which a light amount of an object is effectively read is read. FIG. 5 (b)
Is an example of block readout, in which two pixels on the left side of the figure are shielded as a reference signal output photoelectric conversion element group, two pixels are set as a range to be skipped, and the next two pixels are used as an effective signal output photoelectric conversion element group. Read out the charge.

Next, the operation of reading all the pixels will be described with reference to FIG.
This will be described with reference to an OS sensor block diagram. VSEL1 is first activated by the vertical scanning circuit 20,
The CMOS sensor pixel cells B11, B12, B13 connected to the VSEL1 are selected, and the signal lines Vsig1, Vsig1
The photoelectric conversion signal is output to sig2 and Vsig3. The signal output V
sig1, Vsig2, and Vsig3 are signal holding circuits 21-1, 21-21.
2, 21-3, and are temporarily held by the horizontal scanning circuit 24 in the horizontal direction.
Activate 2-3 to transfer the signal on the output line VH.

The scanned signal is output via the output amplifier 23. The signal holding circuits 21-1, 21-2,
When all the photoelectric conversion signals of 21-3 have been read, the vertical scanning circuit 20 then activates VSEL2,
The signals of the CMOS sensor pixel cells B21, B22, and B23 are similarly converted into signal holding circuits 21-1, 21-2, and 21-3.
The horizontal scanning circuit 24 sequentially activates the selection switches 22-1, 22-2, and 22-3 in the horizontal direction, and transfers the signal to the output line VH.

The scanned signal is output via the output amplifier 23. Next, VSEL3 is activated, and the signals of the CMOS sensor pixel cells B31, B32, and B33 are similarly transmitted to the signal holding circuits 21-1, 21-2, and 21.
-3, and the horizontal scanning circuit 24 activates the selection switches 22-1, 22-2, 22-3 sequentially in the horizontal direction, and transfers the signal to the output line VH. The scanned signal is output via the output amplifier 23.
In this way, all the pixels formed on the imaging surface are read out by combining the vertical and horizontal scanning circuits 20 and 24.

Next, the operation of block reading will be described with reference to FIG. The area read for AE operation is B2
Area 10 surrounded by dotted lines 2, B23, B32, and B33
When it is set to 0, the vertical scanning circuit 20 skips the VSEL1, and first selects the VSEL2. The VSEL2
CMOS sensor pixel cells B21, B connected to
22, B23 are selected, and the signal lines Vsig1, Vsig2, V
Output the photoelectric conversion signal to sig3. The signal outputs Vsig1, V
sig2 and Vsig3 are the signal holding circuits 21-1, 21-2, and 2
It is temporarily stored in 1-3. Here, the horizontal scanning circuit 24
As a result, the selection switch 22-1 skips the reading, first activates the selection switch 22-2, and transfers the signal on the output line VH. Next, the selection switch 22-3 is activated to transfer the signal of the holding circuit 21-3 to the output line VH. The signal transferred on the output line VH is sequentially integrated by the integrator 300.

Next, the vertical scanning circuit 20 is connected to the VSEL3
Select The CMOS connected to the VSEL3
The sensor pixel cells B31, B32, and B33 are selected, and the photoelectric conversion signals are output to the signal lines Vsig1, Vsig2, and Vsig3. The signal outputs Vsig1, Vsig2, Vsig3 are temporarily held in the signal holding circuits 21-1, 21-2, 21-3. Here, the selection switch 22 is controlled by the horizontal scanning circuit 24.
-1 is skipped, and the selection switch 22-2 is first activated to transfer a signal on the output line VH. next,
By activating the selection switch 22-3, the signal of the holding circuit 21-3 is transferred to the output line VH. The signal transferred on the output line VH is successively integrated by the integrator 300. As a result, the block area 1 surrounded by the dotted line
Only 00 is selectively read and integrated as an AE evaluation signal. The integrated value integrated by the integrator 300 is sent to the determiner 13 described in the first embodiment, and used for setting exposure conditions.

Normally, in the case of a still image camera, the automatic exposure apparatus determines the exposure time according to the amount of light at the center of the angle of view. Therefore, as in the case of auto focus, block reading is performed with the central portion as a block,
By removing the noise component, an accurate exposure time can be determined quickly. In addition, even in the case of a video camera that shoots moving images, since the light amount of a constantly changing target object changes, the change is detected at high speed by block reading,
The degree of aperture corresponding to the optimum exposure time is determined from the image output level of block reading, and the light amount to the area sensor at the exposure point is reduced to set a linear characteristic light amount. Thus, a high-sensitivity image signal can be obtained. As described above, the present invention can be applied not only to a still image but also to a moving image pickup device.

[0030]

As described above, according to the present invention,
In a solid-state imaging device that performs imaging using an area sensor,
When setting exposure conditions before photographing, the exposure conditions can be immediately obtained.

In addition, not only in still image shooting but also in moving image shooting, the exposure condition can be determined at high speed by measuring and detecting the partial exposure amount. Is extremely effective.

[Brief description of the drawings]

FIG. 1 is a conceptual block diagram according to an embodiment of the present invention.

FIG. 2 is a conceptual block diagram according to an embodiment of the present invention.

FIG. 3 is a conceptual block diagram according to an embodiment of the present invention.

FIG. 4 is a circuit block diagram of block reading according to the embodiment of the present invention.

FIG. 5 is a conceptual diagram of a reading method according to an embodiment of the present invention.

FIG. 6 is a circuit block diagram of block reading according to the embodiment of the present invention.

FIG. 7 is a conceptual block diagram of a conventional AE.

[Explanation of symbols]

11, 21, 31 Photoelectric conversion device panel (area sensor) 12, 22, Integrating circuit 13, 23, 33 Judgment circuit (Comparison / judgment circuit) 14, 24, 34 Exposure condition setting means 15 CPU 32 Averaging circuit 11 to 22 Photodiode ST11-ST18 Transfer switch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuhito Sakurai, Inventor 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Tetsunobu Mitsuji 3-30-2, Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Tohru Koizumi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Takumi Hiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Narito Sugawa 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 5C022 AA13 AB06 AC42 AC69 5C024 AA01 BA01 CA13 FA01 FA11 GA31 HA17 HA18 HA20 JA10 5C072 AA01 BA13 EA05 FA03 FA07 FA08 FB08 FB19 XA10

Claims (9)

[Claims] 1. A two-dimensionally arranged solid-state imaging device for converting optical information into a photoelectric charge to obtain an output signal, comprising: a block reading means for reading a partial block of the solid-state imaging device; A solid-state imaging device, comprising: holding means for storing the image data; and transfer means for transferring the photocharge newly obtained by accumulation to the holding means and accumulatively adding. 2. The solid-state imaging device according to claim 1, further comprising an integration unit that integrates and outputs all pixel data in the block output from the holding unit. 3. The solid-state imaging device according to claim 1, further comprising an averaging unit that averages and outputs all pixel data in the block output from the holding unit. 4. The solid-state imaging device according to claim 2, wherein photometric information is detected from an output of said integration means. 5. The solid-state imaging device according to claim 3, wherein photometric information is detected from an output of said averaging means. 6. The solid-state imaging device according to claim 1, wherein a result of each unit from the block reading unit to the integration unit is repeated at least twice by changing an exposure condition. 7. A result of each means from said block reading means to said integrating means is changed at least twice by changing an exposure condition, and an exposure condition to reach said predetermined exposure level is calculated from a result of said two integrating means. The solid-state imaging device according to claim 1, wherein: 8. A solid-state imaging device that performs imaging using an area sensor in which a plurality of photoelectric conversion elements are arranged, wherein: a block reading unit that divides an area of the area sensor into a plurality of blocks and reads a photoelectric charge of each block; A solid-state imaging device, comprising: an integrating unit that integrates a photocharge signal of each of the block reading units for each photoelectric conversion element in each of the blocks. 9. An automatic exposure apparatus using an area sensor provided with a plurality of photoelectric conversion means, wherein a block reading means for reading photoelectric charges of photoelectric conversion means of a block in the area sensor, and a photoelectric charge by the block reading means. An automatic exposure apparatus, comprising: integrating means for integrating; and a determination circuit for comparing and determining the integration result of the integrating means with a predetermined exposure level.