JP3988114B2 - Imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides imaging apparatus In particular, an image sensor that outputs a signal of each light receiving unit and the light shielding unit that can stabilize the output signal of each light receiving unit of the image sensor divided using the signal of the light shielding unit of the image sensor Imaging device having About.
[0002]
[Prior art]
In response to the expansion of the internal and external markets, in recent years it has become possible to obtain image sensors with a large number of pixels at a lower cost.
When the number of pixels of this image sensor is increased, reading out a signal with a single readout circuit increases the readout speed, resulting in high component costs and increased current consumption.
Therefore, it is considered to use a plurality of readout circuits, divide the image sensor, and simultaneously read out, thereby reducing the readout speed and reducing the current consumption and the component cost. This will be described.
[0003]
An example of a conventional imaging device compatible with high-definition HDTV will be described below together with specific numerical values with reference to FIG.
An example of a conventional imaging element shown in FIG. 3B is configured by a light receiving unit 31 and a readout circuit 32.
As shown in FIG. 3B, an image sensor having 1920 effective pixels (pixels of the light receiving unit 31) in the horizontal direction is not divided, and a single readout circuit 32 reads out signals from the image sensor. This is a case of reading all at once.
[0004]
When an image sensor having 1920 effective pixels (pixels of the light receiving unit 31) in the horizontal direction is read out by one readout circuit 32, the horizontal frequency is 33.75 kHz and the horizontal blanking period is 280 clocks (from the horizontal synchronization signal to the video). 192 clocks from the signal start point to 88 clocks from the video signal end point to the next horizontal synchronization signal), the operating frequency of one readout circuit 32 is
33.75kHz × (1920 + 280)
= 33.75 kHz x 2200 = 74.25 MHz
It becomes.
[0005]
Next, a case where an image sensor having 1920 effective pixels (pixels of the light receiving unit) in the horizontal direction as shown in FIG. 4 is divided and read by a plurality of readout circuits will be described below.
An example of the image sensor shown in FIG. 4B is composed of light receiving units 41 and 42 divided into two and two readout circuits 43 and 44.
As shown in FIG. 4B, two readout circuits 43 and 44 are provided in the horizontal direction, and the two image pickup elements having 1920 effective pixels (light receiving portions) in the horizontal direction are driven simultaneously. This is a case of reading by the read circuits 43 and 44.
[0006]
When an image sensor having 1920 effective pixels (light-receiving portions) in the horizontal direction is read by the two readout circuits 43 and 44, each of the two is assumed to have a horizontal frequency of 33.75 kHz and a horizontal blanking period of 140 clocks. The operating frequency of the readout circuits 43 and 44 is
33.75 kHz × (960 + 140) = 37.125 MHz
It becomes.
[0007]
When the operation frequency of 37.125 MHz of the two readout circuits described above is compared with the operation frequency of 74.25 MHz of collective readout by one readout circuit, the image sensor is divided into two and read out by the two readout circuits. The operating frequency in this case is ½ of the operating frequency in the case of batch reading, and if the image sensor is divided into two, the reading speed can be reduced to ½.
[0008]
Further, the output current (dark current) of the image sensor when there is no light input has a very strong temperature dependency and is likely to fluctuate. When the image sensor is divided and read, it is necessary to cope with this. .
Therefore, it is desirable to stabilize (clamp) the black level by providing a light receiving portion and a light shielding portion in the pixel portion of the image sensor and sampling the read signal level of the light shielding portion as a reference signal level.
[0009]
The level stabilization method will be specifically described below with reference to the image sensor shown in FIG.
The image sensor shown in FIG. 5 includes 1920 effective pixel (light receiving) portions 52 in the horizontal direction, and pixels that are shielded so that 24 light beams that are not in the configuration of FIG. (Shading) portions 51 and 53 and a readout circuit 54 are included.
Here, the image pickup device includes 1920 effective pixel (light receiving) portions 52 in the horizontal direction and 24 pixel (light shielding) portions 51 and 53 that are shielded so that light does not enter at both ends thereof. Thus, the readout circuit 54 reads out the signals of the pixels of both the light shielding parts 51 and 53 and the light receiving part 52.
[0010]
FIG. 9 shows an example of the configuration of the reading circuit 54.
The shift register control circuit 91 outputs a load pulse (LD) to the shift register 92 in synchronization with the input of the horizontal synchronization signal, and the shift register 92 corresponds to one horizontal line in synchronization with the load pulse (LD). The output signal of each pixel is taken into the shift register 92.
[0011]
The shift register control circuit 91 counts clock pulses starting from the input of the horizontal synchronization signal, and when the count value matches the read start address (TS) preset in the read start address register 54A, Then, a transfer permission flag (SE) for reading is output.
[0012]
Thus, the shift register 92 sequentially outputs the output of each pixel for one line in the horizontal direction as a single element output signal in synchronization with the transfer clock (SCK) with a delay corresponding to the read start address from the horizontal synchronization signal. The signal is output as an element output signal via 93.
[0013]
Now, when incident light as shown in FIG. 5A is incident on the image sensor, a dark current is output from the light shielding portions 51 and 53 regardless of the incident light. The signal shown in 5 (d) is extracted.
Therefore, a clamp circuit 130 including a differential amplifier 131 and a sample hold circuit 132 is provided as shown in FIG. 13, and a clamp pulse is given during the readout period of the light shielding unit 51 as shown in FIG. By clamping the signal level of 51 as the reference signal level, it is possible to obtain a stabilized output so that the black level does not depend on the dark current as shown in FIG.
[0014]
Next, a case where the image pickup device is divided, light shielding portions are provided at both ends thereof, the light receiving portion is divided into two, and reading is performed simultaneously by two reading circuits will be described with reference to FIG.
The imaging element shown in FIG. 6B includes light receiving portions 62 and 63 obtained by dividing a horizontally long rectangular light receiving region in the vertical direction, and light shielding portions 61 and 64 provided on the left and right outer sides adjacent to the light receiving region. And two readout circuits 65 and 66 for reading out each light receiving unit.
[0015]
First, the operation of the readout circuits 65 and 66 of the image sensor will be described below with reference to FIG.
10 includes readout start address registers 65A and 66A, shift register control circuits 101 and 104, shift registers 102 and 105, and output amplifiers 103 and 106. The readout circuits 65 and 66 shown in FIG.
[0016]
The shift register control circuit 101 outputs a load pulse (LD) to the shift register 102 in synchronization with the input of the horizontal synchronization signal, and the shift register 102 corresponds to one horizontal line in synchronization with this load pulse (LD). Output signals (signals from the light shielding unit 61 and the light receiving unit 62) are taken into the shift register 102.
[0017]
The shift register control circuit 101 counts the clock pulses starting from the input of the horizontal synchronization signal, and when the count value matches the read start address (TS) preset in the read start address register 65A, Then, a transfer permission flag (SE) for reading is output.
[0018]
As a result, the shift register 102 uses the output of each pixel for one line in the horizontal direction (signals from the light shielding unit 61 and the light receiving unit 62) as a single element output signal with a delay of the readout start address from the horizontal synchronization signal. In synchronization with (SCK), the output signal is output through the output amplifier 103 as an element output signal.
Similarly, the shift register control circuit 104 counts clock pulses starting from the input of the horizontal synchronization signal, and when the count value matches the read start address (TS) preset in the read start address register 66A, the shift register 105 On the other hand, a transfer permission flag (SE) for reading is output.
[0019]
The shift register 105 uses the output of each pixel for one line in the horizontal direction (signals from the light receiving unit 63 and the light shielding unit 64) as a single element output signal with a transfer clock (SCK) delayed by the readout start address from the horizontal synchronization signal. Are sequentially output via the output amplifier 106 in synchronization with the output.
[0020]
Here, as shown in FIG. 6B, the image pickup element is shielded so that 1920 effective pixels (light receiving unit 62, light receiving unit 63) in the horizontal direction and 24 lights are not input to both ends thereof. However, the area of the light receiving part is divided into two areas (light receiving part 62 and light receiving part 63) for each 960 pixels.
[0021]
In addition, a reading circuit 65 for reading signals from the light shielding unit 61 and the light receiving unit 62 and a reading circuit 66 for reading signals from the light receiving unit 63 and the light shielding unit 64 are provided. The read circuit 66 starts reading at the same time.
Now, when incident light as shown in FIG. 6A is incident on the image sensor, each readout circuit 65 and readout circuit 66 starts readout simultaneously after the readout start address TS = 72 clocks from the horizontal synchronization signal. The readout circuit 65 uses the signals of the light-shielding part 61 and the light-receiving part 62 as the element output 1, and the readout circuit 66 uses the signals of the light-receiving part 63 and the light-shielding part 64 as the element output 2, and FIGS. 6 (d) and 6 (e). ) Is output.
[0022]
Each output (element output 1 and element output 2) from the readout circuit 65 and readout circuit 66 has two differential amplifiers 141 and 142 and one output as shown in FIG. 14 in order to clamp the black level. These are supplied to differential amplifiers 141 and 142 of a clamp circuit 140 composed of a sample hold circuit 143, respectively.
[0023]
The output of the readout circuit 65 (element output 1) is supplied to the sample hold circuit 143, and the output of the sample hold circuit 143 is supplied to the two differential amplifiers 141 and 142, respectively.
In order to sample the signal level of the light shielding unit 61 output from the readout circuit 65 as a reference signal level, a clamp pulse as shown in FIG. 6F is supplied to the sample hold circuit 143 of the clamp circuit 140 of FIG.
[0024]
In the clamp output 2, the reference signal level of the clamp circuit changes while the readout circuit 66 outputs the signal of the light receiving unit 63, and the input light of the light receiving unit 63 changes continuously (uniformly) smoothly. Even so, the output signal is stepped at a position corresponding to the clamp pulse.
[0025]
[Problems to be solved by the invention]
As described above with reference to FIGS. 6 and 14, in the clamp output 2, the reference signal level of the clamp circuit fluctuates while the readout circuit 66 outputs the signal of the light receiving unit 63, and FIG. As shown in FIG. 4, even if the input light of the light receiving unit 63 changes continuously (uniformly) smoothly, the output signal has a step at a position corresponding to the clamp pulse, and the output signal fluctuates illegally. There is a problem that a certain signal (stepped signal) is output.
[0026]
Therefore, the present invention has been made to solve the above problems, An imaging apparatus capable of obtaining a clamp output without a step even if the area of the imaging element is divided two-dimensionally and the element output of the light receiving part of each area is clamped by the signal level of the light shielding part The purpose is to provide.
[0027]
[Means for Solving the Problems]
In order to solve the above-described problem, an imaging apparatus according to the present invention divides an area in which a plurality of pixels are two-dimensionally arranged in a row direction and a column direction into the row direction or the column direction, and at least one of a start end position and an end position. Provided for each of the plurality of light receiving portions of the imaging element, and an imaging element having a pixel portion in which one of the divided regions is a light shielding portion and the remaining plurality of divided regions are light receiving portions, Signals of a plurality of pixels in each of the plurality of light receiving portions are respectively in the same direction When reading out as an element output and there is the light-shielding part adjacent to the corresponding light-receiving part, a plurality of readout circuits for reading out the signal of the light-shielding part as an element output and provided for each of the plurality of readout circuits A plurality of differential amplifiers for clamping an element output from the corresponding readout circuit by inputting a clamp signal for clamping by a signal level of at least one of the light shielding units, and outputting the clamp signal A clamp pulse for input, and an element output from the readout circuit for reading the signal of the one light-shielding part is inputted, and the signal of the one light-shielding part is read based on the input of the clamp pulse, A sample-and-hold circuit that outputs the clamp signal to a plurality of differential amplifiers. The one reading circuit that sequentially reads out the signal of the one light-shielding part and the signal of the light-receiving part adjacent to the one light-shielding part as an element output while reading the signal of the one light-shielding part as an element output The read signal is input to the sample hold circuit, and the other read circuit other than the one read circuit among the plurality of read circuits receives the clamp pulse that the sample hold circuit samples the signal level of the one light shielding portion. The signal of the corresponding light receiving unit is read out as an element output during a period other than the period during which the light is received.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of an image sensor according to the present invention will be described below with reference to the drawings by a preferred example. FIG. 1 shows the imaging of the present invention. apparatus The structure and timing chart of the 1st Example of this are shown. FIG. 1B shows the image sensor. FIG. 7 shows a specific example of a readout circuit constituting this image sensor.
[0029]
In the configuration of the first embodiment of the image sensor of the present invention shown in FIG. 1B, a pixel block composed of a plurality of pixels arranged two-dimensionally in the row direction and the column direction is arranged in the column direction (or row direction). Four pixel units are connected and arranged, the first and fourth blocks are assigned to the light-shielding parts 11 and 14, the second and third blocks are assigned to the light-receiving parts 12 and 13, and the respective light-receiving parts 12 are arranged. , 13 and a peripheral circuit section having two readout circuits 15 and 16 for reading out.
[0030]
As shown in FIG. 7, the read circuits 15 and 16 are constituted by read start start address registers 15A and 16A, shift register control circuits 71 and 76, shift registers (horizontal transfer CCDs) 72 and 75, and output amplifiers 73 and 79, respectively. Has been.
[0031]
In this embodiment, the shift registers 72 and 75 of the readout circuits 15 and 16 are both composed of 984 stages (light shielding unit 24 pixels + light receiving unit 960 pixels), but the readout start address is TS1 = 72 in the readout circuit 15. In the read circuit 16, TS2 = 96 is set in advance in the read start address registers 15A and 16A, respectively.
[0032]
As a result, the readout circuit 15 sequentially reads out the signals of the light-shielding portion 11 and the light-receiving portion 12 in the horizontal direction after TS1 = 72 clocks from the horizontal synchronization signal, while the readout circuit 16 operates in the conventional manner of FIG. Unlike the timing, the reading circuit 15 does not start reading at the same time, and starts reading to the outside from the timing when the reading circuit 15 finishes reading the light shielding unit 11 (TS2 = 96 clocks have elapsed from the horizontal synchronization signal).
[0033]
FIG. 1D and FIG. 1E show outputs (element output 1, element output 2) from the readout circuit 15 and readout circuit 16 to the outside.
The outputs from the readout circuit 15 and readout circuit 16 are output from a clamp circuit 110 composed of two differential amplifiers 111 and 112 and a sample hold circuit 113 shown in FIG. 11 in order to clamp the black level of the readout signal. It is supplied to one input of the differential amplifiers 111 and 112, respectively.
[0034]
The output of the readout circuit 15 (element output 1) is supplied to the sample hold circuit 113 of the clamp circuit 110, and the output of the sample hold circuit 113 is supplied to the other input of the two differential amplifiers 111 and 112, respectively. Is done.
A clamp pulse as shown in FIG. 1 (f) is supplied to the clamp circuit 110 to read a period during which the readout circuit 15 reads the signal of the light shielding unit 11, and the other readout circuits 16 read out the light receiving unit 13. The non-period is read out, and the signal level of the light shielding unit 11 of the readout circuit 15 is sampled as a reference signal.
[0035]
As a result, the clamp output 2 of the clamp circuit 110 can correctly clamp the black level without fluctuation of the reference signal during reading of the light receiving unit 13.
FIGS. 1G and 1H show the clamp output 1 and the clamp output 2 of the output of the clamp circuit 110 of FIG. 11, respectively.
[0036]
In this embodiment, the reading circuit 15 starts reading after the reading circuit 15 reads the light shielding unit 11. However, according to the present invention, the other reading circuits do not read the light receiving unit in all periods of reading the light shielding unit. In the clamp circuit 110, the effect of the present invention can be obtained if the other readout circuit 16 does not read out the light receiving unit 13 only during the period during which the signal level of the light shielding unit 11 is sampled.
[0037]
In the present embodiment, the image sensor provided with the light-shielding portions 11 and 14 at both ends of the light-receiving portions 12 and 13 is used and clamped by the light-shielding portion 11 read out earlier. Instead, only one of them may be used, and the clamp timing may be the light shielding unit 14 that is read later.
[0038]
In this case, the effect of the present invention can be obtained by preventing other readout circuits from reading out the light receiving unit during readout of the light shielding unit 14.
In order to perform clamping using the light shielding unit 14, the time until clamping may be further delayed by 984 stages (light shielding unit 24 pixels + light receiving unit 960 pixels).
Clamping can be performed more stably than when the light shielding unit 11 is used for clamping.
[0039]
In this embodiment, the image sensor is divided by the two light receiving units 12 and 13. However, when any one readout circuit reads the light shielding unit, the other readout circuit does not read the light reception unit. For example, the effect of the present invention can be obtained even if the number of divided light receiving portions is 3 or more.
[0040]
In this embodiment, the readout circuits 15 and 16 are described as the image sensor, or the image sensor including the clamp circuit 110. However, an A / D converter (not shown) for digitizing the clamp output is also described. Even if the image pickup device includes the image pickup device, the same effect can be obtained by using the image pickup device as shown in this embodiment.
[0041]
Next, a second embodiment of the image sensor of the present invention will be described below with reference to the drawings.
FIG. 2 shows a configuration and timing chart of the second embodiment of the image sensor of the present invention.
FIG. 2B shows the configuration of the image sensor. FIG. 8 shows a specific example of a readout circuit constituting the image sensor of the present invention.
[0042]
In the configuration of the second embodiment of the image sensor of the present invention shown in FIG. 2B, a pixel block composed of a plurality of pixels arranged two-dimensionally in the row direction and the column direction is arranged in the column direction (or row direction). 5 pixels are connected and arranged, the first and fifth blocks are assigned to the light-shielding portions 21 and 25, the second to fourth blocks are assigned to the light-receiving portions 22 to 24, and the light-shielding portion 21 The light receiving unit 22, the light receiving unit 23, and a peripheral circuit unit including three read circuits 26 to 28 that respectively read the light receiving unit 24 and the light blocking unit 25.
[0043]
As shown in FIG. 8, the read circuits 26 to 28 include read start start address registers 26A, 27A, 28A, shift register control circuits 81, 84, 87, shift registers (horizontal transfer CCDs) 82, 85, 88, output amplifiers. 83, 86 and 89, respectively.
[0044]
In this embodiment, the shift registers 82 and 88 of the readout circuits 26 and 28 are both configured with 656 stages (light shielding unit 24 pixels + light receiving unit 632 pixels), but the shift register 85 of the readout circuit 27 has 656 stages (light receiving unit). Part 656 pixels).
As for the read start address, TS1 = 72 is set in advance in the read start address register 26A in the read circuit 26, and TS2 and TS3 = 96 clocks are set in the read start address registers 27A and 28A in advance in the read circuits 27 and 28, respectively.
[0045]
As a result, the readout circuit 26 sequentially reads out the signals of the light shielding unit 21 and the light receiving unit 22 in the horizontal direction after TS1 = 72 clocks from the horizontal synchronization signal, while the readout circuits 27 and 28 are the conventional circuits of FIG. Unlike the operation timing, the readout circuit 26 does not start readout at the same time, and readout starts from the timing when the readout circuit 26 finishes reading out the light shielding unit 21 (TS2 = 96 clocks have elapsed from the horizontal synchronization signal).
[0046]
FIGS. 2D, 2E and 2F show outputs from the readout circuits 26 to 28 (element output 1 to element output 3).
Each output from the readout circuits 26 to 28 is the difference between the clamp circuit 120 composed of the three differential amplifiers 121 to 123 and the sample hold circuit 124 shown in FIG. 12 in order to clamp the black level of the readout signal. It is supplied to one input of each of the dynamic amplifiers 121 to 123.
[0047]
The output (element output 1) of the readout circuit 26 is supplied to the sample hold circuit 124 of the clamp circuit 120, and the output of the sample hold circuit 124 is supplied to the other inputs of the three differential amplifiers 121 to 123, respectively. Is done.
A clamp pulse as shown in FIG. 2G is supplied to the clamp circuit 120 to read a period during which the read circuit 26 reads the signal of the light shielding unit 21, and the other read circuits 27 and 28 receive the light receiving unit 23. , 24 is read out, and the signal level of the light shielding portion 21 of the readout circuit 26 is clamped as a reference signal.
[0048]
As a result, the clamp outputs 2 and 3 of the clamp circuit 120 can correctly clamp the black level without the reference signal changing during the reading of the light receiving units 23 and 24.
2 (h), (i) and (j) show the clamp output 1, output 2 and output 3 of the clamp circuit 120 of FIG. 12, respectively.
[0049]
In this embodiment, the reading circuit 26 reads the light shielding unit 21 and then starts reading the reading circuits 27 and 28. However, in the present invention, the other reading circuits use the light receiving unit in all periods of reading the light shielding unit. There is no need to prevent reading, and in the clamp circuit 120, if the other reading circuits 27 and 28 do not read the light receiving portions 23 and 24 only during a period during which the signal level of the light shielding portion 21 is sampled, the effect of the present invention can be obtained. can get.
[0050]
The case where clamping is performed using the light shielding unit 21 at the start end has been described with reference to FIG. 2. On the contrary, when clamping is performed using the light shielding unit 25 at the end, the reading ends of the light receiving units 22 and 23 should be the same. The read start register is set so that the reading of the light shielding unit 25 is started from the timing of the read end. Then, the delay time from the horizontal synchronization signal of the clamp pulse supplied to the clamp circuit may be set so that the signal from the light shielding unit 25 can be clamped.
[0051]
If the read start address register 27A of the read circuit 27 that reads only the light receiving unit 23 in FIG. 2 is configured so that either TS1 or TS2 can be selected, light is shielded corresponding to the clamp pulse supplied from the outside. It can be made to correspond to any of the parts 21 and 25.
[0052]
【The invention's effect】
As described in detail above, a region in which a plurality of pixels are two-dimensionally arranged in the row direction and the column direction is divided in the row direction or the column direction, and at least one of the divided regions of the start and end positions is obtained. Provided for each of the plurality of light receiving portions of the image sensor, and an image sensor having a pixel portion having a light receiving portion with the remaining plurality of divided regions as light receiving portions, Signals of a plurality of pixels in each of the plurality of light receiving portions are respectively in the same direction When reading out as an element output and there is the light-shielding part adjacent to the corresponding light-receiving part, a plurality of readout circuits for reading out the signal of the light-shielding part as an element output and provided for each of the plurality of readout circuits A plurality of differential amplifiers for clamping an element output from the corresponding readout circuit by inputting a clamp signal for clamping by a signal level of at least one of the light shielding units, and outputting the clamp signal A clamp pulse for input, and an element output from the readout circuit for reading the signal of the one light-shielding part is inputted, and the signal of the one light-shielding part is read based on the input of the clamp pulse, A sample-and-hold circuit that outputs the clamp signal to a plurality of differential amplifiers. The one reading circuit that sequentially reads out the signal of the one light-shielding part and the signal of the light-receiving part adjacent to the one light-shielding part as an element output while reading the signal of the one light-shielding part as an element output The read signal is input to the sample hold circuit, and the other read circuit other than the one read circuit among the plurality of read circuits receives the clamp pulse that the sample hold circuit samples the signal level of the one light shielding portion. Since the corresponding light receiving unit signal is read out as an element output outside the period during which the light is received, the clamp prevents the time required to read the simultaneous output signal from the light receiving unit and the output signal from the light shielding unit It is possible to output a suitable signal. Therefore, the signal of each light receiving unit can be clamped in a period when there is no readout signal with reference to the signal of the output light shielding unit, and a stable clamp output with uniform signal levels can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration (in the case of two light receiving units) of a first embodiment of an image pickup device of the present invention and a timing chart.
FIG. 2 is a diagram illustrating a configuration (in the case of three light receiving units) and a timing chart of a second embodiment of the image sensor of the present invention.
FIG. 3 is a diagram illustrating a configuration of an example of a conventional image sensor (in the case of one light receiving unit).
FIG. 4 is a diagram illustrating a configuration of an example of a conventional image sensor (in the case of two light receiving units).
FIG. 5 is a diagram illustrating a timing chart in the case where there is one readout circuit as an example of a conventional image sensor.
FIG. 6 is a timing chart of each readout circuit of an example of a conventional image sensor.
FIG. 7 is a diagram showing a first embodiment of a readout circuit constituting the image sensor of the present invention.
FIG. 8 is a diagram showing a second embodiment of the readout circuit constituting the image sensor of the present invention.
FIG. 9 is a diagram illustrating an example of a readout circuit of a general image sensor.
FIG. 10 is a diagram illustrating an example of a readout circuit of a conventional image sensor.
FIG. 11 is a diagram showing a configuration of a clamp circuit used in the present invention.
FIG. 12 is a diagram showing a configuration of a clamp circuit used in the present invention.
FIG. 13 is a diagram showing an example of a configuration of a conventional clamp circuit.
FIG. 14 is a diagram showing an example of a configuration of a conventional clamp circuit.
[Explanation of symbols]
11, 14, 21, 25 Shading part
12, 13, 22-24
15, 16, 26-28 readout circuit
15A, 16A, 26A to 28A Read start address register
71, 74, 81, 84, 87 Shift register control circuit
72, 75, 82, 85, 88 Shift register (horizontal transfer CCD)
73, 76, 83, 86, 89 Output amplifier
110,120 Clamp circuit
111, 112, 121-123 Differential amplifier
113,124 Sample hold circuit
LD Load pulse
SCK transfer clock
SE transfer permission flag
TS, TS1 to TS3 Read start address (time from horizontal synchronization signal to pixel read start)

Claims (1)

An area in which a plurality of pixels are two-dimensionally arranged in a row direction and a column direction is divided in the row direction or the column direction, and at least one of the start end and the end position is set as a light shielding portion, and the remaining plurality An image sensor having a pixel portion with the divided region of
Provided for each of the plurality of light receiving units of the image sensor, and reads out signals of a plurality of pixels in each of the plurality of light receiving units as element outputs in the same direction, and there is the light shielding unit adjacent to the corresponding light receiving unit A plurality of readout circuits for reading out the signal of the light-shielding part as an element output,
Provided for each of the plurality of readout circuits, and each of the plurality of differences for clamping the element output from the corresponding readout circuit by inputting a clamp signal for clamping by the signal level of at least one of the light shielding units. Dynamic amplifier,
A clamp pulse for outputting the clamp signal is inputted, and an element output from the readout circuit for reading out the signal of the one light shielding portion is inputted, and the signal of the one light shielding portion is inputted based on the input of the clamp pulse. A sample and hold circuit that outputs the clamp signal to the plurality of differential amplifiers, and
The clamp pulse is obtained by reading one signal from the one light-shielding part and one signal from the light-receiving part adjacent to the one light-shielding part in order as an element output. Input to the sample and hold circuit while
Among the plurality of readout circuits, readout circuits other than the one readout circuit correspond to periods other than the period in which the clamp pulse for sampling the signal level of the one light shielding portion is input by the sample hold circuit. Read the signal of the light receiving unit as an element output,
An imaging apparatus characterized by that.

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