WO2021187333A1 - 撮像装置およびそのゲイン比取得方法 - Google Patents
撮像装置およびそのゲイン比取得方法 Download PDFInfo
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- 238000000034 method Methods 0.000 title claims description 35
- 238000012360 testing method Methods 0.000 claims abstract description 92
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- 238000006243 chemical reaction Methods 0.000 claims description 35
- 238000003384 imaging method Methods 0.000 claims description 31
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 10
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/76—Addressed sensors, e.g. MOS or CMOS sensors
- H04N25/78—Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N17/00—Diagnosis, testing or measuring for television systems or their details
- H04N17/002—Diagnosis, testing or measuring for television systems or their details for television cameras
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/50—Control of the SSIS exposure
- H04N25/51—Control of the gain
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/60—Noise processing, e.g. detecting, correcting, reducing or removing noise
- H04N25/67—Noise processing, e.g. detecting, correcting, reducing or removing noise applied to fixed-pattern noise, e.g. non-uniformity of response
- H04N25/671—Noise processing, e.g. detecting, correcting, reducing or removing noise applied to fixed-pattern noise, e.g. non-uniformity of response for non-uniformity detection or correction
- H04N25/673—Noise processing, e.g. detecting, correcting, reducing or removing noise applied to fixed-pattern noise, e.g. non-uniformity of response for non-uniformity detection or correction by using reference sources
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/60—Noise processing, e.g. detecting, correcting, reducing or removing noise
- H04N25/68—Noise processing, e.g. detecting, correcting, reducing or removing noise applied to defects
- H04N25/69—SSIS comprising testing or correcting structures for circuits other than pixel cells
Definitions
- This technology relates to an image sensor. More specifically, the present invention relates to a calibration technique between gains in a level adjustment circuit in an image sensor.
- the adaptive gain control (AGC: Adaptive Gain Control) function that reads at high gain at low illuminance and low gain at high illuminance has been used in the level adjustment circuit.
- AGC Adaptive Gain Control
- the high gain data is placed between the high gain and the low gain in the digital circuit after the AD converter (Analog to Digital Converter).
- AD converter Analog to Digital Converter
- the actual gain ratio is calculated by calibration and the gain ratio shift. Will need to be corrected.
- an imaging device that stochastically changes a threshold value has been proposed as a technique for eliminating the inconvenience associated with switching the exposure amount (see, for example, Patent Document 1).
- This technology was created in view of this situation, and aims to reduce the time required for calibration between gains in the level adjustment circuit.
- the present technology has been made to solve the above-mentioned problems, and the first aspect thereof is that the level adjustment of the analog signal output to the vertical signal line corresponding to each column of the pixel array is different from each other.
- a level adjustment circuit performed by either the first or second gain, an analog digital converter that converts the level-adjusted analog signal into a digital signal, and a test signal that generates first and second test signals that are different from each other.
- the first gain of the level adjustment circuit and the first gain of the level adjustment circuit are supplied by supplying the first test signal to one of the generation unit and the vertical signal line and at the same time supplying the second test signal to the other of the vertical signal lines.
- An image pickup apparatus including a gain ratio acquisition unit for acquiring a gain ratio with a second gain, and a gain ratio acquisition method thereof. This has the effect of simultaneously supplying different test signals to one and the other of the vertical signal lines to obtain a gain ratio.
- the gain ratio correction value generation unit that generates the gain ratio correction value based on the acquired gain ratio and the gain ratio correction value generated by the gain ratio correction value generation unit.
- a correction unit that corrects the digital signal may be further provided. This has the effect of correcting the digital signal based on the acquired gain ratio.
- the test signal generation unit generates a potential of high illuminance data as the first test signal and a potential of low illuminance data as the second test signal. May be good. This has the effect of generating the potentials of the high illuminance data and the low illuminance data as test signals.
- one of the vertical signal lines may be the vertical signal line of the odd-numbered column, and the other of the vertical signal lines may be the vertical signal line of the even-numbered column. This has the effect of utilizing different test signals between adjacent columns.
- the gain ratio acquisition unit sets the gain of the level adjustment circuit to 0 dB, the first gain and the second gain, respectively, for each of the gains of the vertical signal line.
- the second test signal is supplied to one of the vertical signal lines at the same time as the vertical signal.
- the first test signal may be supplied to the other side of the line to obtain the gain ratio. This has the effect of sequentially switching and supplying the first and second test signals on one and the other of the vertical signal lines to acquire the gain ratio.
- the analog-digital converter is provided for each of the plurality of vertical signal lines, and the gain ratio acquisition unit supplies one of the vertical signal lines with the first test signal.
- the second test signal is supplied to the other side of the vertical signal line, and the gain of the level adjustment circuit is set to 0 dB, and the vertical gain is set for each of the first gain and the second gain.
- the first and second test signals supplied to either one or the other of the signal lines may be sequentially selected to obtain the gain ratio. This has the effect of sequentially switching and supplying the first and second test signals in the path from one and the other of the vertical signal lines to the analog-to-digital converter to acquire the gain ratio.
- a first sample holding unit that holds an analog signal output to one of the vertical signal lines and a second sample holding unit that holds an analog signal output to the other of the vertical signal lines.
- the level adjustment circuit further includes a sample hold unit, and the level adjustment circuit sequentially performs the level adjustment for the output of either the first or second sample hold unit, and the analog-digital converter performs a plurality of the level adjustments. AD conversion may be sequentially performed on the output of the circuit. As a result, the analog signals from one and the other of the vertical signal lines are switched and supplied by the first and second sample hold units, and the gain ratio is acquired.
- each of the first and second sample hold portions may be provided with two sample hold circuits that operate alternately with each other. This brings about the effect of simultaneously operating the sampling operation and the AD conversion operation in the pipeline.
- the level adjustment circuit is an analog gain circuit that outputs a voltage signal whose level is adjusted by adjusting the level of the analog signal, and the analog digital converter converts the voltage signal into the digital signal. It may be a single slope type analog-digital converter.
- the level adjusting circuit is a voltage-current converter that outputs a current signal whose level is adjusted by adjusting the level of the analog signal, and the analog-digital converter converts the current signal into the digital signal. It may be a current input type analog-to-digital converter.
- FIG. 1 is a diagram showing an overall configuration example of an image pickup apparatus according to a first embodiment of the present technology. It is a figure which shows the circuit configuration example for every pixel string of the column signal processing circuit 100 in 1st Embodiment of this technique. It is a figure which shows the circuit structure example for the gain ratio correction in the 1st Embodiment of this technique. It is a figure for demonstrating the acquisition method of the gain ratio correction value at the time of calibration in the 1st Embodiment of this technique. It is a figure which shows the operation timing example of the calibration in 1st Embodiment of this technique. It is a figure which shows the operation timing example of the image pickup apparatus in the 1st Embodiment of this technique.
- FIG. 1 is a diagram showing an overall configuration example of an image pickup apparatus according to a first embodiment of the present technology.
- This imaging device includes a pixel array 10 and a peripheral circuit unit.
- the peripheral circuit unit includes a vertical drive circuit 20, a horizontal drive circuit 30, a column signal processing circuit 100, and an output circuit 60.
- the pixel array 10 is a pixel array in which a plurality of pixels 11 including a photoelectric conversion unit are arranged in a two-dimensional array.
- the pixel 11 includes, for example, a photodiode that serves as a photoelectric conversion unit, and a plurality of pixel transistors.
- the plurality of pixel transistors can be composed of, for example, three transistors, a transfer transistor, a reset transistor, and an amplification transistor.
- the vertical drive circuit 20 drives the pixels 11 in units of rows.
- the vertical drive circuit 20 is composed of, for example, a shift register.
- the vertical drive circuit 20 selects the pixel drive wiring and supplies a pulse for driving the pixel 11 to the selected pixel drive wiring.
- the vertical drive circuit 20 selectively scans each pixel 11 of the pixel array 10 in a row-by-row manner in the vertical direction, and a pixel signal based on the signal charge generated in the photoelectric conversion unit of each pixel 11 according to the amount of light received. Is supplied to the column signal processing circuit 100 via the vertical signal line (VSL) 19.
- VSL vertical signal line
- the horizontal drive circuit 30 drives the column signal processing circuit 100 in column units.
- the horizontal drive circuit 30 is composed of, for example, a shift register.
- the horizontal drive circuit 30 sequentially outputs each of the column signal processing circuits 100 by sequentially outputting horizontal scanning pulses, and transmits pixel signals from each of the column signal processing circuits 100 to a horizontal signal via a switch 31. Output to line 59.
- the peripheral circuit section is provided with a control circuit (not shown).
- This control circuit controls the entire image pickup apparatus, receives an input clock and data for instructing an operation mode, and outputs data such as internal information of the image pickup apparatus. That is, this control circuit generates a clock signal or a control signal that serves as a reference for the operation of the vertical drive circuit 20, the column signal processing circuit 100, the horizontal drive circuit 30, etc., based on the vertical synchronization signal, the horizontal synchronization signal, and the master clock. do. Then, these signals are input to the vertical drive circuit 20, the column signal processing circuit 100, the horizontal drive circuit 30, and the like.
- the column signal processing circuit 100 performs signal processing such as noise removal for each pixel string (column) with respect to the signal output from the pixel 11 for one row. That is, the column signal processing circuit 100 performs signal processing such as correlated double sampling processing (CDS: Correlated Double Sampling) for removing fixed pattern noise peculiar to the pixel 11, signal amplification, analog-to-digital conversion, and the like.
- CDS Correlated Double Sampling
- the column signal processing circuit 100 includes a load MOS 140, an analog gain circuit 160, and an AD converter 190 for each pixel sequence.
- the load MOS (LM: Load Metal-Oxide-Semiconductor) 140 is a MOS transistor connected to each of the vertical signal lines 19, and functions as a current source 141.
- the analog gain circuit (AG: Analog Gain) 160 is a circuit that adjusts the level of an analog signal input from the load MOS 140 with a predetermined gain.
- the AD converter (ADC: Analog to Digital Converter) 190 is a circuit that converts an analog signal, which is a voltage signal from the analog gain circuit 160, into a digital signal.
- the analog gain circuit 160 is an example of the level adjustment circuit described in the claims.
- the output circuit 60 performs signal processing on signals sequentially supplied from each of the pixel strings of the column signal processing circuit 100 through the horizontal signal line 59 and outputs the signals. At that time, the output circuit 60 buffers the signal from the column signal processing circuit 100. Further, the output circuit 60 may perform black level adjustment, column variation correction, various digital signal processing, and the like on the signal from the column signal processing circuit 100.
- this image pickup apparatus is provided with a test voltage generation circuit and outputs a test voltage.
- Each of the vertical signal lines 19 is provided with a selector 134, and according to the control signal from the input switching control circuit 133, either the pixel signal from the vertical signal line 19 or the test voltage from the test voltage generation circuit is selected. It is configured to supply the load MOS 140.
- the test voltage generation circuit includes a resistor 111, a current source 112, a selector 113, and a voltage control register 114.
- a current from the current source 112 flows through the resistor 111 connected in series, and the potential at each end point is input to the input terminal of the selector 113.
- a voltage control register 114 is connected to the selection signal terminal of the selector 113, and the selector 113 outputs a voltage signal corresponding to the value of the voltage control register 114 from the output terminal to the signal lines 121 and 122. That is, the voltage signals output to the signal lines 121 and 122 can be switched by changing the set value of the voltage control register 114.
- the resistor 111, the current source 112, and the selector 113 are examples of the test signal generation unit described in the claims. Further, the voltage control register 114, the input switching control circuit 133, and the selector 134 are examples of the gain ratio acquisition unit described in the claims.
- Output buffers 131 and 132 are connected to the signal lines 121 and 122 on the output side of the selector 113, respectively.
- the output of one output buffer 131 corresponds to the odd-numbered column vertical signal line 19
- the output of the other output buffer 132 corresponds to the even-numbered column vertical signal line 19.
- the output of the output buffer 131 and the output of the output buffer 132 can be short-circuited by the switch 139, and the same voltage signal can be supplied to the odd-numbered column and the even-numbered column.
- the switch is used. 139 is used open.
- the potential VH of the high-intensity data is applied to the signal line 121 and the potential VL of the low-intensity data is applied to the signal line 122, the potential VH of the high-intensity data is output to the odd column and the even column.
- the potential VL of low-light data is output to.
- the potential VL of the low-illumination data is applied to the signal line 121 and the potential VH of the high-illumination data is applied to the signal line 122, the potential VL of the low-illumination data is output to the odd column and the high-illumination data is output to the even column.
- the potential VH of is output.
- FIG. 2 is a diagram showing a circuit configuration example for each pixel string of the column signal processing circuit 100 according to the first embodiment of the present technology.
- the column signal processing circuit 100 includes a load MOS 140, an analog gain circuit 160, and an AD converter 190 for each pixel sequence.
- a single slope type analog-to-digital converter is assumed as the AD converter 190.
- an AGC comparator 170 is provided to perform adaptive gain control (AGC) in the analog gain circuit 160.
- the AGC comparator 170 includes a comparator 172, a flip-flop 173, and a selector 174.
- the comparator 172 compares the input voltage value with the AGC threshold value and determines whether the input voltage value has low illuminance or high illuminance.
- the analog gain circuit 160 that receives this determination result uses a high gain (HG: High Gain) if the illuminance is low, and uses a low gain (LG: Low Gain) if the illuminance is high.
- the flip-flop 173 is a flip-flop that holds the determination result by the comparator 172. That is, it holds whether the input voltage value is determined to be low illuminance or high illuminance in the immediately preceding determination result.
- the selector 174 selects either the value held in the flip-flop 173 or the manually set value according to the selection signal (manual setting EN) and supplies it to the analog gain circuit 160.
- the value held in the flip-flop 173 is supplied to the analog gain circuit 160, but when calibrating between gains, a manually set value is used as described later.
- the analog gain circuit 160 includes an analog gain amplifier 161.
- the analog gain amplifier 161 amplifies the analog data signal input from the load MOS 140 according to the gain of the gain signal (high gain or low gain) input from the AGC comparator 170.
- the AD converter 190 includes a lamp signal generation circuit 191, a comparator 192, and a counter 194.
- the lamp signal generation circuit 191 generates a lamp signal to be compared with the input signal.
- a ramp signal is a signal whose signal level monotonically increases or decreases over time.
- the lamp signal generation circuit 191 is composed of, for example, a digital-to-analog converter (DAC: Digital to Analog Converter).
- the comparator 192 compares the lamp signal from the lamp signal generation circuit 191 with the input signal and determines the magnitude relationship between them.
- the counter 194 counts the time until the magnitude relationship is reversed according to the determination result by the comparator 192. Thereby, the input signal which is an analog signal can be converted into a digital signal.
- FIG. 3 is a diagram showing an example of a circuit configuration for gain ratio correction according to the first embodiment of the present technology.
- the selector 134 selects either the pixel signal from the pixel 11 or the test voltage from the test voltage generation circuit 110. Although the middle part is omitted in the figure, the gain ratio correction is performed on the output signal output from the output circuit 60 in the signal processing unit in the subsequent stage.
- This signal processing unit includes a switch 310, a correction value calculation circuit 320, and a correction circuit 330.
- the correction value calculation circuit 320 calculates and holds the correction value by calibration.
- the correction value calculation circuit 320 includes a gain ratio correction value calculation circuit 321 and a correction memory 322.
- the gain ratio correction value calculation circuit 321 calculates a correction value for gain ratio correction by calibration, as will be described later.
- the correction memory 322 stores the calculation result by the gain ratio correction value calculation circuit 321 as the gain ratio correction value 324.
- the correction value calculation circuit 320 is an example of the gain ratio correction value generation unit described in the claims.
- the correction circuit 330 corrects the gain ratio according to the correction value calculated by the correction value calculation circuit 320.
- the correction circuit 330 includes a line buffer 331 and a multiplier 332.
- the line buffer 331 is a buffer that holds the output signal output from the output circuit 60 line by line.
- the multiplier 332 corrects the gain ratio by multiplying the signal held in the line buffer 331 by the gain ratio correction value 324 stored in the correction memory 322.
- the correction circuit 330 is an example of the correction unit described in the claims.
- the switch 310 is a switch that distributes the output signal output from the output circuit 60 to the correction value calculation circuit 320 or the correction circuit 330.
- the switch 310 outputs the test voltage from the test voltage generation circuit 110 to the correction value calculation circuit 320 at the time of calibration, and outputs the pixel signal from the pixel 11 to the correction circuit 330 at the time of reading the pixel data.
- the gain ratio is corrected at the time of reading the pixel data by the correction value calculated at the time of calibration.
- FIG. 4 is a diagram for explaining a method of acquiring a gain ratio correction value at the time of calibration in the first embodiment of the present technology.
- the graph in the figure shows analog values on the horizontal axis and digital codes on the vertical axis.
- the analog gain circuit 160 switches between high gain and low gain to control the gain by the AGC function.
- the AGC function of the analog gain circuit 160 is turned off and the analog gain is manually controlled to acquire the digital value after AD conversion when analog low-light data and high-light data are input for each gain. ..
- the digital values of the low illuminance data and the high illuminance data are acquired for the reference gain of 0 dB. It is assumed that the low gain is, for example, 12 dB, and the high gain is, for example, 24 dB.
- the line average (average of all columns) of the illuminance difference between the low illuminance data and the high illuminance data is calculated for each gain.
- the line average UD 0 of the illuminance difference of 0 dB is expressed as the difference between the average UH of the high illuminance data and the average UL of the low illuminance data.
- UD 0 (UH-UL)
- the line average UD LG of the low gain illuminance difference is expressed as the difference between the average UH LG of the high illuminance data and the average UL LG of the low illuminance data, which is the measured gain of low gain with respect to the reference gain of 0 dB. It equals multiplied by UD 0 in the ratio G 'LG.
- the line average UD HG of the high gain illuminance difference is expressed as the difference between the average UH HG of the high illuminance data and the average UL HG of the low illuminance data, which is the actual measurement of the high gain with respect to the reference 0 dB gain. It is equal to the gain ratio G'HG multiplied by UD 0.
- the low gain correction value C LG and the high gain correction value C HG are calculated.
- the ideal gain ratio of low gain to the reference 0 dB gain is G LG
- the ideal gain ratio of high gain to the reference 0 dB gain is G HG .
- C LG (UD 0 / UD LG ) x
- G LG (G LG / G'LG )
- C HG (UD LG / UD HG ) x
- FIG. 5 is a diagram showing an example of calibration operation timing according to the first embodiment of the present technology.
- the AGC of the analog gain circuit 160 Prior to reading the data, the AGC of the analog gain circuit 160 is calibrated in one horizontal detection period (1XHS: 1 Horizontal Sync signal period). At the time of this calibration, in addition to the low gain and high gain of the analog gain circuit 160, the potential VH of the high illuminance data and the potential VL of the low illuminance data are set for a total of three gains of the reference 0 dB gain. Used as a test voltage. At that time, according to the above configuration, the test data acquisition time can be shortened by performing the parallel operation by using different voltage signals for the odd-numbered column and the even-numbered column as the test voltage.
- the test voltage generation circuit 110 and the vertical signal line 19 are used. Switch between connections on a timely basis. That is, after the potential VH of the high-intensity data is output to the odd-numbered columns and the potential VL of the low-intensity data is output to the even-numbered columns, the potential VL of the low-intensity data is output to the odd-numbered columns and the potential of the high-intensity data is output to the even-numbered columns. The operation of outputting VH is repeated. As a result, the information of the high illuminance data and the low illuminance data can be uniformly acquired for each gain.
- FIG. 6 is a diagram showing an example of operation timing of the image pickup apparatus according to the first embodiment of the present technology.
- Pixel reset is performed prior to reading the data signal. That is, in the pixel 11, the electric charge is reset, and the time for settling the voltage value of the vertical signal line 19 by this reset is secured. At this time, the AGC comparator 170 also performs the settling time by resetting in the same manner.
- the AD converter 190 After reset settling, the AD converter 190 performs AD conversion of the reset signal. At that time, the gain adjustment is performed in both the high gain and the low gain in the analog gain circuit 160.
- the exposed charge is transferred as a data signal, and the time for settling the voltage value of the vertical signal line 19 by the data signal is secured.
- the comparison device 172 of the AGC comparator 170 compares the input voltage value with the AGC threshold value, and the comparison result is held in the flip-flop 173.
- the AD conversion at the next timing when reading the pixel data, the value held in the flip-flop 173 is selected in the selector 174, and the gain of the analog gain circuit 160 is set according to the comparison result with the AGC threshold value. That is, the gain is adjusted by the analog gain circuit 160 using the gain of high gain in the case of low illuminance and the gain of low gain in the case of high illuminance, and the AD conversion is performed by the AD converter 190.
- the comparison result with the AGC threshold value is not used, and the manually set value is selected in the selector 174. That is, a high gain is set for a high gain calibration, and a low gain is set for a low gain calibration.
- test data is performed by performing parallel operation by using different voltage signals for odd-numbered columns and even-numbered columns as test voltages when calibrating AGC. Acquisition time can be shortened. Further, by switching the voltage signal between the odd-numbered column and the even-numbered column in a time-division manner, deterioration of the correction accuracy can be prevented.
- Second Embodiment> In the first embodiment described above, deterioration of correction accuracy is prevented by switching the test signal in time division between odd-numbered columns and even-numbered columns.
- a test signal is provided on the premise that a plurality of sets of an analog gain circuit and a plurality of sample hold circuits sharing the analog gain circuit are provided and pipeline operation is performed in each set. A technique for preventing deterioration of correction accuracy without switching between the two will be described.
- FIG. 7 is a diagram showing an overall configuration example of the image pickup apparatus according to the second embodiment of the present technology.
- the overall configuration of the imaging device in this second embodiment is basically the same as that in the first embodiment described above.
- one AD converter 190 is shared among the four pixel trains, and one analog gain circuit 160 is shared by the two pixel trains. That is, two analog gain circuits 160 are connected to one AD converter 190.
- a sample hold unit 150 is connected between the load MOS 140 of each pixel row and the analog gain circuit 160.
- one AD converter 190 is provided with two sets of an analog gain circuit 160 and two sample hold units 150 sharing the analog gain circuit 160. Further, each of the sample hold units 150 further includes two sample hold circuits as shown below. In the second embodiment, a single-slope analog-digital converter is assumed as the AD converter 190, as in the first embodiment described above.
- FIG. 8 is a diagram showing a configuration example of the column signal processing circuit 100 according to the second embodiment of the present technology.
- two analog gain circuits 160 are connected to one AD converter 190, and two sample hold units 150 are connected to each of the analog gain circuits 160.
- four sample hold units 150 connected to one AD converter 190 are distinguished as SH # 0 to # 3.
- Each of the sample hold units 150 includes two sample hold circuits 151 and 152, a comparator 172, and a flip-flop 173.
- the sample hold circuits 151 and 152 are hold circuits that operate alternately at opposite timings by switches provided for input and output.
- the sample hold circuit 151 is referred to as the front side (F: Foreground)
- the sample hold circuit 152 is referred to as the back side (B: Background).
- the comparator 172 and the flip-flop 173 are similar to those of the AGC comparator 170 described in the first embodiment described above.
- the analog gain circuit 160 includes an analog gain amplifier 161 as described in the first embodiment described above.
- a switch provided on the data signal input side of the analog gain amplifier 161 inputs a data signal from either of the two sample hold units 150.
- the output of the selector 174 is connected to the gain input side of the analog gain amplifier 161.
- the selector 174 is similar to that of the AGC comparator 170 described in the first embodiment described above. However, a gain signal from any one of the two sample hold units 150 is input by a switch provided on the input side of the selector 174.
- the AD converter 190 is the same as the first embodiment described above, and includes a lamp signal generation circuit 191, a comparator 192, and a counter 194, and converts an analog input signal into a digital signal and outputs the signal. ..
- FIG. 9 is a diagram showing a data flow of the column signal processing circuit 100 according to the second embodiment of the present technology.
- one sample hold circuit 151 is regarded as the front side and the other sample hold circuit 152 is regarded as the back side, and they operate alternately. That is, behind the AD conversion of the data held in one sample hold circuit, the next data signal is sampled in parallel in the other sample hold circuit. On the contrary, behind the sampling of the data signal in one sample hold circuit, the data held in the other sample hold circuit is AD-converted.
- the AD conversion is performed by time division sharing the AD converter 190 and the two analog gain circuits 160. That is, one AD converter 190 divides four analog signals from the four sample hold units 150 in one horizontal detection period into four phases # 0 to # 3 and performs AD conversion.
- FIG. 10 is a diagram showing an example of calibration operation timing according to the second embodiment of the present technology.
- the four analog signals from the four sample hold units 150 in one horizontal detection period are divided into four phases # 0 to # 3 and AD-converted.
- the potential VH of the high illuminance data is supplied to the odd column, and the potential VL of the low illuminance data is supplied to the even column.
- AD conversion of the potential VH of the high illuminance data is performed in the phases # 0 and # 1
- AD conversion of the potential VL of the low illuminance data is performed in the phases # 2 and # 3.
- both the potential VH and VL data are obtained for each gain in one AD converter 190.
- FIG. 11 is a diagram showing an example of operation timing of the imaging device according to the second embodiment of the present technology.
- Pixel reset is performed prior to reading the data signal. That is, in the pixel 11, the electric charge is reset, and the time for settling the voltage value of the vertical signal line 19 by this reset is secured.
- the reset signal is held by the four sample hold circuits 151 in the four sample hold units 150.
- the AGC comparator 170 also performs settling by resetting in the same manner.
- the reset signals held in the four sample hold circuits 151 are divided into four phases # 0 to # 3, and AD conversion is performed in the AD converter 190. That is, in phase # 0, the signal from SH # 0 is AD-converted, in phase # 1, the signal from SH # 2 is AD-converted, in phase # 2, the signal from SH # 1 is AD-converted, and phase # 3 In, the signal from SH # 3 is AD-converted. This reading order is for avoiding a collision in the analog gain circuit 160.
- the gain is selected based on the comparison result of the AGC comparator 170 at the time of reading the pixel data, but since the determination is not performed at the time of AD conversion of the reset signal, the analog gain circuit 160 Gain adjustment is performed at both high gain and low gain.
- the exposed charge is transferred as a data signal in the pixel 11, and the time for settling the voltage value of the vertical signal line 19 by the data signal is secured.
- the data signal is held by the four sample hold circuits 152 in the four sample hold units 150.
- the input voltage value and the AGC threshold value are compared in the comparator 172, and the comparison result is held in the flip-flop 173.
- the data signals held in the four sample hold circuits 152 are divided into four phases # 0 to # 3, and AD conversion is performed in the AD converter 190. That is, in phase # 0, the signal from SH # 0 is AD-converted, in phase # 1, the signal from SH # 2 is AD-converted, in phase # 2, the signal from SH # 1 is AD-converted, and phase # 3 In, the signal from SH # 3 is AD-converted.
- the gain is selected based on the comparison result of the AGC comparator 170 at the time of reading the pixel data.
- the comparison result with the AGC threshold value is not used, and the manually set value is selected in the selector 174. That is, a high gain is set for a high gain calibration, and a low gain is set for a low gain calibration.
- the potential VH of the high illuminance data and the potential VL of the low illuminance data are AD-converted by dividing them into phases, so that the test voltage is not switched at the time of calibration. , The acquisition time of test data can be shortened.
- FIG. 12 is a diagram showing an overall configuration example of the image pickup apparatus according to the third embodiment of the present technology.
- the overall configuration of the image pickup apparatus in the third embodiment is basically the same as that in the first embodiment described above. However, since it is premised that a current input type analog-to-digital converter is used as the AD converter 190, a dual sample hold unit 250 and a voltage-current converter (V2I) 260 are provided instead of the analog gain circuit 160.
- V2I voltage-current converter
- the dual sample hold unit 250 holds each of the reset signal and the data signal of the vertical signal line 19 as a voltage.
- the voltage-current converter 260 converts the voltage difference (potential difference) between the reset signal and the data signal held in the dual sample hold unit 250 into a current.
- analog correlation double sampling processing (analog CDS) is performed by utilizing the potential difference between the reset signal and the data signal held in the dual sample hold unit 250. Thereby, the fixed pattern noise peculiar to the pixel 11 can be removed.
- the image pickup apparatus when converting a potential difference into a current, the level is adjusted by a predetermined gain. Therefore, similarly to the analog gain circuit 160 in the first and second embodiments described above, it becomes necessary to calibrate the gains in order to correct the gain ratio deviation between the high gain and the low gain. .. Therefore, the image pickup apparatus according to the third embodiment also includes a test voltage generation circuit and outputs a test voltage.
- the voltage-current converter 260 is an example of the level adjustment circuit described in the claims.
- the operation timing of the calibration of the imaging device in the third embodiment is the same as that in the first embodiment described above. That is, the potential VH of the high illuminance data and the potential VL of the low illuminance data are used as test voltages for a total of three gains of the reference 0 dB gain in addition to the low gain and high gain of the voltage-current converter 260. NS. At that time, the acquisition time of the test data can be shortened by performing the parallel operation by using different voltage signals for the odd-numbered column and the even-numbered column as the test voltage.
- FIG. 13 is a diagram showing a configuration example of the column signal processing circuit 100 according to the third embodiment of the present technology.
- a current input type analog-to-digital converter is assumed as the AD converter 190, and a dual sample hold unit 250 and a voltage-current converter 260 are provided.
- the dual sample hold unit 250 includes a reset signal sample hold unit 280-1, a data signal sample hold unit 280-2, and an AGC comparator 270.
- the reset signal sample hold unit 280-1 and the data signal sample hold unit 280-2 both have a switched capacitor configuration, and include a sampling capacitor 281, a differential amplifier 282, and switches 283 to 286, respectively.
- the reset signal sample hold unit 280-1 holds the reset signal.
- the switches 283 and 284 are turned on during the reset period (t1).
- the difference "Vin (t1) -Vref" between the voltage Vin (t1) during the reset period and the reference potential Vref is applied to the sampling capacitor 281 to maintain the voltage.
- the switches 285 and 286 are turned on, the voltage of the reset signal is supplied to the voltage-current converter 260.
- the data signal sample hold unit 280-2 holds the data signal.
- switches 283 and 284 are turned on.
- the difference "Vin (t2) -Vref" between the voltage Vin (t2) during the reset period and the reference potential Vref is applied to the sampling capacitor 281 to maintain the voltage.
- the switches 285 and 286 are turned on, the voltage of the data signal is supplied to the voltage-current converter 260.
- the AGC comparator 270 is a switched capacitor type comparator that performs adaptive gain control (AGC), and includes a sampling capacitor 271, a differential amplifier 272, switches 273 and 274, a flip-flop 275, and a selector 276.
- AGC adaptive gain control
- the switches 273 and 274 are turned on to store electric charge in the sampling capacitor 271. Then, during the data sampling period (t2), the switch 273 is turned on and the switch 274 is turned off. As a result, the potential difference (Vin (t1) -Vin (t2)) between the voltage Vin (t1) in the reset period (t1) and the voltage Vin (t2) in the data sampling period (t2) is held in the sampling capacitor 271.
- the selector 276 selects either the value held in the flip-flop 275 or the manually set value according to the selection signal (manual setting EN) and supplies it to the voltage-current converter 260.
- the value held in the flip-flop 275 is supplied to the voltage-current converter 260, but when performing calibration between gains, manually set values are used as described later.
- the voltage-current converter 260 includes a current source 261, transistors 262 and 264, and a variable resistor 263.
- a current source 261 When the switches 285 and 286 of the reset signal sample hold unit 280-1 are turned on, the voltage of the reset signal is applied between the gate and source of the transistor 262. Further, when the switches 285 and 286 of the data signal sample hold unit 280-2 are turned on, the voltage of the data signal is applied between the gate and the source of the transistor 264.
- a variable resistor 263 is provided on the path from the current source 261 to the AD converter 190, and the resistance value of the variable resistor 263 supplies the current corresponding to the voltage difference between the reset signal and the data signal to the AD converter 190. Will be done.
- the control signal of the variable resistor 263 is supplied from the AGC comparator 270. For example, if "1 (high illuminance)", a low gain (LG) control signal is supplied to the variable resistor 263, and if "0 (low illuminance)", a high gain (HG) control signal is supplied to the variable resistor 263.
- the resistance value according to is selected.
- FIG. 14 is a diagram showing an example of operation timing of the image pickup apparatus according to the third embodiment of the present technology.
- Pixel reset is performed prior to reading the data signal. That is, in the pixel 11, the electric charge is reset, and the time for settling the voltage value of the vertical signal line 19 by this reset is secured. At this time, the AGC comparator 270 also performs the settling time by resetting in the same manner.
- the exposed charge is transferred as a data signal, and the time for settling the voltage value of the vertical signal line 19 by the data signal is secured.
- the comparison device 272 of the AGC comparator 270 compares the input voltage value with the AGC threshold value, and the comparison result is held in the flip-flop 275.
- the potential difference between the reset signal and the data signal is converted into a current by the voltage-current converter 260.
- the gain is adjusted by either high gain or low gain according to the comparison result of the AGC comparator 270. That is, the gain is adjusted by the voltage-current converter 260 using the gain of high gain in the case of low illuminance and the gain of low gain in the case of high illuminance, and the AD conversion is performed by the AD converter 190.
- the comparison result with the AGC threshold value is not used, and the manually set value is selected in the selector 276. That is, a high gain is set for a high gain calibration, and a low gain is set for a low gain calibration.
- the same technique as that of the first embodiment assuming the single slope type analog-to-digital converter is used as the AD converter 190 for the current input type analog-to-digital conversion. It can also be used when a vessel is used.
- FIG. 15 is a diagram showing an overall configuration example of the image pickup apparatus according to the fourth embodiment of the present technology.
- the overall configuration of the image pickup apparatus in the fourth embodiment is basically the same as that in the second embodiment described above. However, since it is premised that a current input type analog-to-digital converter is used as the AD converter 190, the dual sample hold unit 250 and the voltage / current are replaced with the analog gain circuit 160 as in the case of the third embodiment. It is equipped with a converter (V2I) 260.
- V2I converter
- one AD converter 190 is shared among the four pixel trains, and one voltage / current converter 260 is shared among the two pixel trains. That is, two voltage-current converters 260 are connected to one AD converter 190. Further, two dual sample hold units 250 are connected to one load MOS 140 between the load MOS 140 of each pixel row and the voltage / current converter 260.
- one AD converter 190 is provided with two sets of a voltage-current converter 260 and four dual sample hold units 250 sharing the same.
- the operation timing of the calibration of the imaging device in the fourth embodiment is the same as that in the second embodiment described above. That is, the four analog signals from the four dual sample hold units 250 in one horizontal detection period are divided into four phases # 0 to # 3 for AD conversion.
- the potential VH of the high illuminance data is supplied to the odd column, and the potential VL of the low illuminance data is supplied to the even column.
- AD conversion of the potential VH of the high illuminance data is performed in the phases # 0 and # 1
- AD conversion of the potential VL of the low illuminance data is performed in the phases # 2 and # 3.
- the potentials VH and VL are sequentially supplied to the AD converter 190 for each phase, so that the test voltage is switched in each of the odd-numbered column and the even-numbered column as in the first and third embodiments described above. It is possible to shorten the acquisition time of test data.
- FIG. 16 is a diagram showing a configuration example of the column signal processing circuit 100 according to the fourth embodiment of the present technology.
- two voltage-current converters 260 are connected to one AD converter 190, and four dual sample hold units 250 are connected to each of the voltage-current converters 260. ..
- eight dual sample hold units 250 connected to one AD converter 190 are divided into front (F) and back (B) as in the second embodiment, and dual S / H # 0. Distinguish as -F, # 0-B, # 1-F, # 1-B, # 2-F, # 2-B, # 3-F, # 3-B.
- Each configuration of the dual sample hold unit 250 is the same as that of the third embodiment described above.
- FIG. 17 is a diagram showing a data flow of the column signal processing circuit 100 according to the fourth embodiment of the present technology.
- the dual sample hold unit 250 is divided into a front side (F) and a back side (B) and operates alternately. That is, the data held in one dual sample hold unit 250 is AD-converted, and the next data is sampled simultaneously and in parallel by the other dual sample hold unit 250. On the contrary, the data held in the other dual sample hold unit 250 is AD-converted behind the data being sampled by one dual sample hold unit 250.
- the AD conversion is performed by time division sharing the AD converter 190 and the two voltage / current converters 260. That is, one AD converter 190 divides four analog signals from the four dual sample hold units 250 in one horizontal detection period into four phases # 0 to # 3 and performs AD conversion.
- FIG. 18 is a diagram showing an example of operation timing of the image pickup apparatus according to the fourth embodiment of the present technology.
- Pixel reset is performed prior to reading the data signal. That is, in the pixel 11, the electric charge is reset, and the time for settling the voltage value of the vertical signal line 19 by this reset is secured. Here, it is assumed that the reset signal is held by the four dual sample hold units 250. At this time, the AGC comparator 270 also performs settling by resetting in the same manner.
- the AGC comparator 270 also setstles the data signal in the same manner and compares it with the threshold value.
- the reset signal and data signal held in each of the four dual sample hold units 250 and the comparison result in the AGC comparator 270 are used in the voltage-current converter 260 for analog with either low gain or high gain. Gain adjustment is performed.
- AD conversion is performed in the AD converter 190 in four phases # 0 to # 3. That is, the signal from the dual S / H # 0-F is AD-converted in the phase # 0, the signal from the dual S / H # 2-F is AD-converted in the phase # 1, and the dual S / H is converted in the phase # 2.
- the signal from # 1-F is AD-converted, and the signal from dual S / H # 3-F is AD-converted in phase # 3. This reading order is for avoiding a collision in the voltage-current converter 260.
- the other four dual sample hold units 250 newly perform pixel reset and its settling and data.
- the signal is settled.
- the AGC comparator 270 also setstles the data signal in the same manner and compares it with the threshold value.
- the voltage-current converter 260 uses the reset and data signals held in the four dual sample hold units 250 in the previous cycle and the comparison results in the AGC comparator 270 to achieve low or high gain.
- the analog gain is adjusted by either of the above.
- AD conversion is performed in the AD converter 190 in four phases # 0 to # 3. That is, the signal from the dual S / H # 0-B is AD-converted in the phase # 0, the signal from the dual S / H # 2-B is AD-converted in the phase # 1, and the dual S / H is converted in the phase # 2.
- the signal from # 1-B is AD-converted, and the signal from dual S / H # 3-B is AD-converted in phase # 3.
- the same process is repeated while alternately reversing the roles of the front and back.
- the same technique as that of the second embodiment assuming the single slope type analog-to-digital converter is used as the AD converter 190 for the current input type analog-to-digital conversion. It can also be used when a vessel is used.
- the present technology can have the following configurations.
- a level adjustment circuit that adjusts the level of the analog signal output to the vertical signal line corresponding to each column of the pixel array by either the first and second gains that are different from each other.
- An analog-to-digital converter that converts the level-adjusted analog signal into a digital signal
- a test signal generator that generates first and second test signals that are different from each other, At the same time that the first test signal is supplied to one of the vertical signal lines, the second test signal is supplied to the other of the vertical signal lines to supply the first gain and the second gain of the level adjustment circuit.
- An imaging device including a gain ratio acquisition unit that acquires a gain ratio between.
- a gain ratio correction value generator that generates a gain ratio correction value based on the acquired gain ratio, and a gain ratio correction value generation unit.
- the imaging device according to (1) further comprising a correction unit that corrects the digital signal according to the gain ratio correction value generated by the gain ratio correction value generation unit.
- the test signal generation unit generates a potential of high illuminance data as the first test signal and generates a potential of low illuminance data as the second test signal.
- One of the vertical signal lines is the vertical signal line of the odd-numbered column.
- the imaging device according to any one of (1) to (3) above, wherein the other of the vertical signal lines is a vertical signal line of an even-numbered column.
- the gain ratio acquisition unit sets the gain of the level adjustment circuit to 0 dB, the first gain, and the second gain, respectively, on one of the vertical signal lines. After supplying the second test signal to the other of the vertical signal lines at the same time as supplying the test signal, the second test signal is supplied to one of the vertical signal lines and at the same time, the second test signal is supplied to the other of the vertical signal lines.
- the imaging apparatus according to any one of (1) to (3) above, wherein the test signal of 1 is supplied and the gain ratio is acquired.
- the analog-to-digital converter is provided for each of the plurality of vertical signal lines.
- the gain ratio acquisition unit supplies the first test signal to one of the vertical signal lines and at the same time supplies the second test signal to the other of the vertical signal lines to reduce the gain of the level adjustment circuit to 0 dB.
- the first and second test signals supplied to either one or the other of the vertical signal lines are sequentially selected for each gain set for each of the first gain and the second gain.
- the imaging device according to any one of (1) to (5) above, which acquires the gain ratio.
- a first sample hold unit that holds an analog signal output to one of the vertical signal lines, and a first sample hold unit.
- a second sample hold unit for holding the analog signal output to the other side of the vertical signal line is further provided.
- the level adjustment circuit sequentially performs the level adjustment for the output of either the first or second sample hold unit, and then sequentially performs the level adjustment.
- each of the first and second sample hold portions includes two sample hold circuits that operate alternately with each other.
- the level adjustment circuit is an analog gain circuit that outputs a voltage signal whose level is adjusted by adjusting the analog signal.
- the imaging device according to any one of (1) to (5) above, wherein the analog-to-digital converter is a single-slope analog-digital converter.
- the level adjustment circuit is a voltage-current converter that outputs a current signal whose level is adjusted by adjusting the analog signal.
- the analog-to-digital converter is an image pickup device according to any one of (1) to (4) or (6) to (8), which is a current input type analog-to-digital converter that converts the current signal into the digital signal.
- (11) A level adjustment circuit that adjusts the level of the analog signal output to the vertical signal line corresponding to each column of the pixel array by either the first and second gains different from each other, and the level-adjusted analog signal.
- an imaging device including an analog digital converter that converts A procedure for supplying the first test signal to one of the vertical signal lines to obtain a gain ratio between the first gain and the second gain of the level adjustment circuit
- an image pickup apparatus in which the procedure of supplying the second test signal to the other side of the vertical signal line and acquiring the gain ratio between the first gain and the second gain of the level adjustment circuit is simultaneously performed.
- Gain ratio acquisition method In an imaging device including an analog digital converter that converts A procedure for supplying the first test signal to one of the vertical signal lines to obtain a gain ratio between the first gain and the second gain of the level adjustment circuit, and In an image pickup apparatus in which the procedure of supplying the second test signal to the other side of the vertical signal line and acquiring the gain ratio between the first gain and the second gain of the level adjustment circuit is simultaneously performed.
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Abstract
Description
1.第1の実施の形態(テスト電圧発生回路でテスト電圧を時分割に変更する例)
2.第2の実施の形態(AD変換器への経路上でテスト電圧を切り替える例)
3.第3の実施の形態(第1の実施の形態において電流入力型AD変換器を想定した例)
4.第4の実施の形態(第2の実施の形態において電流入力型AD変換器を想定した例)
[撮像装置]
図1は、本技術の第1の実施の形態における撮像装置の全体構成例を示す図である。
図2は、本技術の第1の実施の形態におけるカラム信号処理回路100の画素列毎の回路構成例を示す図である。
図3は、本技術の第1の実施の形態におけるゲイン比補正のための回路構成例を示す図である。
図4は、本技術の第1の実施の形態におけるキャリブレーション時のゲイン比補正値の取得方法を説明するための図である。
UD0=(UH-UL)
UDLG=UHLG-ULLG=G'LG×(UH-UL)
UDHG=UHHG-ULHG=G'HG×(UH-UL)
CLG=(UD0/UDLG)×GLG=(GLG/G'LG)
CHG=(UDLG/UDHG)×CLG
=(G'LG/G'HG)×(GLG/G'LG)=(GLG/G'HG)
図5は、本技術の第1の実施の形態におけるキャリブレーションの動作タイミング例を示す図である。
上述の第1の実施の形態では、奇数カラムと偶数カラムでテスト信号を時分割で切り替えることにより、補正精度の劣化防止を図っていた。これに対し、この第2の実施の形態では、アナログゲイン回路とそれを共有する複数のサンプルホールド回路のセットを複数セット設けて、それぞれのセットにおいてパイプライン動作を行うことを前提として、テスト信号の切替えを行うことなく補正精度の劣化を防止する技術について説明する。
図7は、本技術の第2の実施の形態における撮像装置の全体構成例を示す図である。
図8は、本技術の第2の実施の形態におけるカラム信号処理回路100の構成例を示す図である。
図10は、本技術の第2の実施の形態におけるキャリブレーションの動作タイミング例を示す図である。
上述の第1の実施の形態ではAD変換器190としてシングルスロープ型アナログデジタル変換器を想定していたが、この第3の実施の形態ではAD変換器190として電流入力型アナログデジタル変換器を想定する。なお、この電流入力型アナログデジタル変換器の具体例としては、デルタシグマ型AD変換器が挙げられる。
図12は、本技術の第3の実施の形態における撮像装置の全体構成例を示す図である。
図13は、本技術の第3の実施の形態におけるカラム信号処理回路100の構成例を示す図である。
図14は、本技術の第3の実施の形態における撮像装置の動作タイミング例を示す図である。
上述の第2の実施の形態ではAD変換器190としてシングルスロープ型アナログデジタル変換器を想定していたが、この第4の実施の形態ではAD変換器190として電流入力型アナログデジタル変換器を想定する。
図15は、本技術の第4の実施の形態における撮像装置の全体構成例を示す図である。
図16は、本技術の第4の実施の形態におけるカラム信号処理回路100の構成例を示す図である。
図18は、本技術の第4の実施の形態における撮像装置の動作タイミング例を示す図である。
(1)画素アレイの各カラムに対応する垂直信号線に出力されたアナログ信号のレベル調整を互いに異なる第1および第2のゲインの何れかにより行うレベル調整回路と、
前記レベル調整されたアナログ信号をデジタル信号に変換するアナログデジタル変換器と、
互いに異なる第1および第2のテスト信号を生成するテスト信号生成部と、
前記垂直信号線の一方に前記第1のテスト信号を供給すると同時に前記垂直信号線の他方に前記第2のテスト信号を供給して前記レベル調整回路の前記第1のゲインと前記第2のゲインとの間のゲイン比を取得するゲイン比取得部と
を具備する撮像装置。
(2)前記取得されたゲイン比に基づいてゲイン比補正値を生成するゲイン比補正値生成部と、
前記ゲイン比補正値生成部によって生成された前記ゲイン比補正値に従って前記デジタル信号を補正する補正部と
をさらに具備する前記(1)に記載の撮像装置。
(3)前記テスト信号生成部は、前記第1のテスト信号として高照度データの電位を生成し、前記第2のテスト信号として低照度データの電位を生成する
前記(1)または(2)に記載の撮像装置。
(4)前記垂直信号線の一方は、奇数番目のカラムの垂直信号線であり、
前記垂直信号線の他方は、偶数番目のカラムの垂直信号線である
前記(1)から(3)のいずれかに記載の撮像装置。
(5)前記ゲイン比取得部は、前記レベル調整回路のゲインを0dB、前記第1のゲインおよび前記第2のゲインのそれぞれに設定したゲイン毎に、前記垂直信号線の一方に前記第1のテスト信号を供給すると同時に前記垂直信号線の他方に前記第2のテスト信号を供給した後に、前記垂直信号線の一方に前記第2のテスト信号を供給すると同時に前記垂直信号線の他方に前記第1のテスト信号を供給して前記ゲイン比を取得する
前記(1)から(3)のいずれかに記載の撮像装置。
(6)前記アナログデジタル変換器は、複数の前記垂直信号線ごとに設けられ、
前記ゲイン比取得部は、前記垂直信号線の一方に前記第1のテスト信号を供給すると同時に前記垂直信号線の他方に前記第2のテスト信号を供給して、前記レベル調整回路のゲインを0dB、前記第1のゲインおよび前記第2のゲインのそれぞれに設定したゲイン毎に、前記垂直信号線の一方および他方の何れかに供給された前記第1および第2のテスト信号を順次選択して前記ゲイン比を取得する
前記(1)から(5)のいずれかに記載の撮像装置。
(7)前記垂直信号線の一方に出力されたアナログ信号を保持する第1のサンプルホールド部と、
前記垂直信号線の他方に出力されたアナログ信号を保持する第2のサンプルホールド部とをさらに具備し、
前記レベル調整回路は、前記第1および第2のサンプルホールド部の何れかの出力について前記レベル調整を順次行い、
前記アナログデジタル変換器は、複数の前記レベル調整回路の出力についてAD変換を順次行う
前記(6)に記載の撮像装置。
(8)前記第1および第2のサンプルホールド部の各々は、互いに交互に動作する2つのサンプルホールド回路を備える
前記(7)に記載の撮像装置。
(9)前記レベル調整回路は、前記アナログ信号をレベル調整した電圧信号を出力するアナログゲイン回路であり、
前記アナログデジタル変換器は、シングルスロープ型アナログデジタル変換器である
前記(1)から(5)のいずれかに記載の撮像装置。
(10)前記レベル調整回路は、前記アナログ信号をレベル調整した電流信号を出力する電圧電流変換器であり、
前記アナログデジタル変換器は、前記電流信号を前記デジタル信号に変換する電流入力型アナログデジタル変換器である
前記(1)から(4)または(6)から(8)のいずれかに撮像装置。
(11)画素アレイの各カラムに対応する垂直信号線に出力されたアナログ信号のレベル調整を互いに異なる第1および第2のゲインの何れかにより行うレベル調整回路と、前記レベル調整されたアナログ信号をデジタル信号に変換するアナログデジタル変換器と、互いに異なる第1および第2のテスト信号を生成するテスト信号生成部とを備える撮像装置において、
前記垂直信号線の一方に前記第1のテスト信号を供給して前記レベル調整回路の前記第1のゲインと前記第2のゲインとの間のゲイン比を取得する手順と、
前記垂直信号線の他方に前記第2のテスト信号を供給して前記レベル調整回路の前記第1のゲインと前記第2のゲインとの間のゲイン比を取得する手順と
を同時に行う撮像装置におけるゲイン比取得方法。
11 画素
19 垂直信号線(VSL:Vertical Signal Line)
20 垂直駆動回路
30 水平駆動回路
31 スイッチ
59 水平信号線
60 出力回路
100 カラム信号処理回路
110 テスト電圧発生回路
111 抵抗
112 電流源
113 セレクタ
114 電圧制御レジスタ
131、132 出力バッファ
133 入力切替制御回路
134 セレクタ
139 スイッチ
141 電流源
150 サンプルホールド部
151、152 サンプルホールド回路
160 アナログゲイン回路
161 アナログゲインアンプ
170 AGC(Adaptive Gain Control)コンパレータ
172 比較器
173 フリップフロップ
174 セレクタ
190 AD(Analog to Digital)変換器
191 ランプ信号生成回路
192 比較器
194 カウンタ
250 デュアルサンプルホールド部
260 電圧電流変換器(V2I)
310 スイッチ
320 補正値算出回路
321 ゲイン比補正値算出回路
322 補正メモリ
324 ゲイン比補正値
330 補正回路
331 ラインバッファ
332 乗算器
Claims (11)
- 画素アレイの各カラムに対応する垂直信号線に出力されたアナログ信号のレベル調整を互いに異なる第1および第2のゲインの何れかにより行うレベル調整回路と、
前記レベル調整されたアナログ信号をデジタル信号に変換するアナログデジタル変換器と、
互いに異なる第1および第2のテスト信号を生成するテスト信号生成部と、
前記垂直信号線の一方に前記第1のテスト信号を供給すると同時に前記垂直信号線の他方に前記第2のテスト信号を供給して前記レベル調整回路の前記第1のゲインと前記第2のゲインとの間のゲイン比を取得するゲイン比取得部と
を具備する撮像装置。 - 前記取得されたゲイン比に基づいてゲイン比補正値を生成するゲイン比補正値生成部と、
前記ゲイン比補正値生成部によって生成された前記ゲイン比補正値に従って前記デジタル信号を補正する補正部と
をさらに具備する請求項1記載の撮像装置。 - 前記テスト信号生成部は、前記第1のテスト信号として高照度データの電位を生成し、前記第2のテスト信号として低照度データの電位を生成する
請求項1記載の撮像装置。 - 前記垂直信号線の一方は、奇数番目のカラムの垂直信号線であり、
前記垂直信号線の他方は、偶数番目のカラムの垂直信号線である
請求項1記載の撮像装置。 - 前記ゲイン比取得部は、前記レベル調整回路のゲインを0dB、前記第1のゲインおよび前記第2のゲインのそれぞれに設定したゲイン毎に、前記垂直信号線の一方に前記第1のテスト信号を供給すると同時に前記垂直信号線の他方に前記第2のテスト信号を供給した後に、前記垂直信号線の一方に前記第2のテスト信号を供給すると同時に前記垂直信号線の他方に前記第1のテスト信号を供給して前記ゲイン比を取得する
請求項1記載の撮像装置。 - 前記アナログデジタル変換器は、複数の前記垂直信号線ごとに設けられ、
前記ゲイン比取得部は、前記垂直信号線の一方に前記第1のテスト信号を供給すると同時に前記垂直信号線の他方に前記第2のテスト信号を供給して、前記レベル調整回路のゲインを0dB、前記第1のゲインおよび前記第2のゲインのそれぞれに設定したゲイン毎に、前記垂直信号線の一方および他方の何れかに供給された前記第1および第2のテスト信号を順次選択して前記ゲイン比を取得する
請求項1記載の撮像装置。 - 前記垂直信号線の一方に出力されたアナログ信号を保持する第1のサンプルホールド部と、
前記垂直信号線の他方に出力されたアナログ信号を保持する第2のサンプルホールド部とをさらに具備し、
前記レベル調整回路は、前記第1および第2のサンプルホールド部の何れかの出力について前記レベル調整を順次行い、
前記アナログデジタル変換器は、複数の前記レベル調整回路の出力についてAD変換を順次行う
請求項6記載の撮像装置。 - 前記第1および第2のサンプルホールド部の各々は、互いに交互に動作する2つのサンプルホールド回路を備える
請求項7記載の撮像装置。 - 前記レベル調整回路は、前記アナログ信号をレベル調整した電圧信号を出力するアナログゲイン回路であり、
前記アナログデジタル変換器は、前記電圧信号を前記デジタル信号に変換するシングルスロープ型アナログデジタル変換器である
請求項1記載の撮像装置。 - 前記レベル調整回路は、前記アナログ信号をレベル調整した電流信号を出力する電圧電流変換器であり、
前記アナログデジタル変換器は、前記電流信号を前記デジタル信号に変換する電流入力型アナログデジタル変換器である
請求項1記載の撮像装置。 - 画素アレイの各カラムに対応する垂直信号線に出力されたアナログ信号のレベル調整を互いに異なる第1および第2のゲインの何れかにより行うレベル調整回路と、前記レベル調整されたアナログ信号をデジタル信号に変換するアナログデジタル変換器と、互いに異なる第1および第2のテスト信号を生成するテスト信号生成部とを備える撮像装置において、
前記垂直信号線の一方に前記第1のテスト信号を供給して前記レベル調整回路の前記第1のゲインと前記第2のゲインとの間のゲイン比を取得する手順と、
前記垂直信号線の他方に前記第2のテスト信号を供給して前記レベル調整回路の前記第1のゲインと前記第2のゲインとの間のゲイン比を取得する手順と
を同時に行う撮像装置におけるゲイン比取得方法。
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JP2008141609A (ja) * | 2006-12-04 | 2008-06-19 | Canon Inc | 光電変換装置及び撮像システム |
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