WO2022113474A1 - Solid-state imaging element and imaging apparatus - Google Patents

Abstract

Provided is a solid-state imaging element in which an analog-to-digital converter (ADC) including a comparator is disposed, wherein the operation of the comparator is stabilized.　A pair of differential transistors amplify a differential between an input voltage and a predetermined reference voltage. An auto-zero transistor opens and closes a path between the gate and drain of one of the pair of differential transistors. An auto-zero potential generating circuit generates an auto-zero potential such that the amount of variation due to process variations is substantially the same as the amount of gate-source variations of the differential transistors, and supplies the potential to the gate of the other of the pair of differential transistors.

Description

Solid-state image sensor and image sensor

This technology relates to a solid-state image sensor. More specifically, the present invention relates to a solid-state image sensor that performs analog-to-digital conversion using a comparator, and an image pickup device.

Conventionally, in a solid-state image sensor or the like, an ADC (Analog to Digital Converter) has been used to convert an analog pixel signal into a digital signal. For example, a solid-state image sensor has been proposed in which a fixed externally applied voltage is applied to an input terminal on the lamp side of a comparator in a single-slope ADC (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-197773

In the above-mentioned conventional technique, the voltage of the input terminal of the comparator is initialized to an appropriate value at the time of auto-zero operation by the externally applied voltage. However, the lower limit of the operating range of the comparator may fluctuate due to process variation, and at that time, the auto-zero voltage determined by the externally applied voltage deviates from the operating range and the operation of the comparator is unstable. May become.

This technique was created in view of such a situation, and aims to stabilize the operation of the comparator in the solid-state image sensor in which the ADC including the comparator is arranged.

The present technology has been made to solve the above-mentioned problems, and the first aspect thereof is a pair of differential transistors that amplify the difference between an input voltage and a predetermined reference voltage, and the above-mentioned pair of differences. An auto-zero transistor that opens and closes the path between one gate and drain of a dynamic transistor and an auto-zero potential whose fluctuation amount due to process variation is substantially the same as the fluctuation amount of the gate-source voltage of the differential transistor are generated. It is a solid-state imaging device including an auto-zero potential generation circuit that supplies to the other gate of a pair of differential transistors. This has the effect of stabilizing the operation of the comparator.

Further, in the first aspect, the auto-zero transistor is a pMOS (p-channel Metal Oxide Semiconductor) transistor, and the pair of differential transistors is an nMOS (n-channel MOS) transistor, and the auto-zero potential generation is performed. The circuit may include an external pMOS transistor in an on state, an external nMOS transistor in an on state, and an external current mirror transistor that supplies a current to the external pMOS transistor and the external nMOS transistor. As a result, the prolongation of the settling time of auto zero is suppressed, and the operation of the comparator is stabilized.

Further, in the first aspect, the auto-zero transistor and the pair of differential transistors are nMOS transistors, and the auto-zero potential generation circuit supplies a current to the on-state external nMOS transistor and the external nMOS transistor. It may include an external current mirror transistor. This has the effect of improving robustness.

Further, in the first aspect thereof, a current mirror circuit and a pair of cascode transistors inserted between the pair of differential transistors and the current mirror circuit are further provided, and the auto-zero potential generation circuit is described above. One of the pair of cascode transistors may be controlled to be turned on within a predetermined auto-zero period. This has the effect of reducing the input offset voltage of the comparator.

Further, in the first aspect, the comparator further comprising a pixel array portion in which a plurality of pixels are arranged in a two-dimensional lattice, and includes the pair of differential transistors and the auto-zero transistor is the pixel array. It may be arranged in each row of parts. This has the effect of performing analog-to-digital conversion on a column-by-column basis.

Further, in this first aspect, the auto-zero potential generation circuit may be arranged for each of the above columns. This has the effect of generating an auto-zero potential for each row.

Further, in this first aspect, the auto-zero potential generation circuit may be shared by the respective comparators in a plurality of rows. This has the effect of reducing the circuit scale.

The second aspect of the present technology is a pair of differential transistors that amplify the difference between the input voltage and a predetermined reference voltage and output it as a pixel signal, and one gate and drain of the pair of differential transistors. An auto-zero transistor that opens and closes the path between the transistors and an auto-zero potential whose fluctuation amount due to process variation is substantially the same as the fluctuation amount between the gate and source of the differential transistor are generated at the other gate of the pair of differential transistors. It is an image pickup apparatus including an auto-zero potential generation circuit for supplying and a signal processing circuit for processing image data in which the pixel signals are arranged. This has the effect of stabilizing the operation of the comparator in the image pickup device.

It is a block diagram which shows one configuration example of the image pickup apparatus in the 1st Embodiment of this technique. It is a block diagram which shows one structural example of the solid-state image sensor in 1st Embodiment of this technique. It is a circuit diagram which shows one structural example of a pixel in 1st Embodiment of this technique. It is a block diagram which shows one structural example of the column ADC in the 1st Embodiment of this technique. It is a circuit diagram which shows one configuration example of the auto-zero potential generation circuit and the comparator in the ADC in the 1st Embodiment of this technique. It is a timing chart which shows an example of the operation of the solid-state image pickup device in the 1st Embodiment of this technique. It is a graph which shows an example of the characteristic of the comparator in the 1st Embodiment of this technique. It is a circuit diagram which shows one structural example of the auto-zero potential generation circuit and the comparator in the 2nd Embodiment of this technique. It is a circuit diagram which shows one structural example of the auto-zero potential generation circuit and the comparator according to the 3rd Embodiment of this technique. It is a timing chart which shows an example of the operation of the solid-state image sensor in the 3rd Embodiment of this technique. It is a figure for demonstrating the effect in the 3rd Embodiment of this technique. It is a block diagram which shows one structural example of the column ADC in the 4th Embodiment of this technique. It is a block diagram which shows an example of the schematic structure of a vehicle control system. It is explanatory drawing which shows an example of the installation position of the vehicle exterior information detection unit and the image pickup unit. It is a figure which shows an example of the schematic structure of an endoscopic surgery system. It is a block diagram which shows an example of the functional structure of the camera head and CCU shown in FIG.

Hereinafter, a mode for carrying out the present technique (hereinafter referred to as an embodiment) will be described. The explanation will be given in the following order.
1. 1. First embodiment (example of supplying an auto-zero potential that fluctuates due to variation)
2. 2. Second embodiment (an example of using only an N-type transistor and supplying an auto-zero potential that fluctuates due to variation)
3. 3. Third embodiment (an example in which a cascode transistor is inserted and an auto-zero potential that fluctuates due to variation is supplied).
4. Fourth embodiment (an example in which a circuit that supplies an auto-zero potential that fluctuates due to variation is shared by a plurality of columns)
5. Application example to moving body 6. Application example to endoscopic surgery system

<1. First Embodiment>
[Configuration example of image pickup device]
FIG. 1 is a block diagram showing a configuration example of an image pickup apparatus 100 according to a first embodiment of the present technology. The image pickup device 100 captures image data, and includes an optical system 110, a solid-state image pickup element 200, a signal processing circuit 120, a memory 130, and a monitor 140.

The optical system 110 collects incident light and guides it to the solid-state image sensor 200. The optical system 110 includes one or a plurality of lenses.

The solid-state image sensor 200 generates image data by photoelectric conversion in synchronization with a vertical synchronization signal. The vertical synchronization signal is a periodic signal indicating the imaging timing, and the frequency is, for example, 30 hertz (Hz). The solid-state image sensor 200 supplies the generated image data to the signal processing circuit 120.

The signal processing circuit 120 performs various signal processing such as demosaic processing and white balance correction processing on the image data. The signal processing circuit 120 supplies the processed image data to the memory 130 and the monitor 140. It should be noted that some or all of the processing performed by the signal processing circuit 120 can be performed in the solid-state image sensor 200.

The memory 130 stores image data. The monitor 140 displays image data.

[Structure example of solid-state image sensor]
FIG. 2 is a block diagram showing a configuration example of the solid-state image sensor 200 according to the first embodiment of the present technology. The solid-state image sensor 200 includes a vertical scanning circuit 211, a timing control circuit 212, a DAC (Digital to Analog Converter) 213, a pixel array unit 214, a column ADC 230, and a horizontal transfer scanning circuit 215.

Pixels 220 are arranged in a two-dimensional grid pattern in the pixel array unit 214. Hereinafter, the set of pixels 220 arranged in the horizontal direction is referred to as a “row”, and the set of pixels 220 arranged in the vertical direction is referred to as a “column”. The pixel 220 photoelectrically converts the incident light to generate an analog pixel signal.

The vertical scanning circuit 211 selects and drives rows in order, and outputs a pixel signal to the column ADC 230. The timing control circuit 212 controls the operation timings of the vertical scanning circuit 211, the DAC 213, the column ADC 230, and the horizontal transfer scanning circuit 215 in synchronization with the vertical synchronization signal.

The DAC 213 generates a predetermined reference signal and supplies it to the column ADC 230. As the reference signal, for example, a saw wavy lamp signal is used.

The column ADC 230 is provided with an ADC for each column, and performs AD (Analog to Digital) conversion for each pixel signal of the column. The column ADC 230 sequentially outputs the digital signals after AD conversion to the signal processing circuit 120 under the control of the horizontal transfer scanning circuit 215. For each row, AD conversion of the pixel signal of each column in the row is executed, and AD conversion is executed for all rows, so that one image data is generated.

The horizontal transfer scanning circuit 215 controls the column ADC 230 to output digital signals in order.

[Pixel configuration example]
FIG. 3 is a circuit diagram showing a configuration example of the pixel 220 according to the first embodiment of the present technology. The pixel 220 includes a photoelectric conversion element 221, a transfer transistor 222, a reset transistor 223, a floating diffusion layer 224, an amplification transistor 225, and a selection transistor 226.

The photoelectric conversion element 221 photoelectrically converts incident light to generate an electric charge. The transfer transistor 222 transfers electric charges from the photoelectric conversion element 221 to the stray diffusion layer 224 according to the transfer signal TRG from the vertical scanning circuit 211.

The reset transistor 223 is initialized by extracting electric charges from the floating diffusion layer 224 according to the reset signal RST from the vertical scanning circuit 211. The floating diffusion layer 224 accumulates electric charges and generates a voltage according to the amount of electric charges.

The amplification transistor 225 amplifies the voltage of the stray diffusion layer 224. The selection transistor 226 outputs a signal of the amplified voltage as a pixel signal according to the selection signal SEL from the vertical scanning circuit 211.

Further, a vertical signal line 229 is wired in the pixel array unit 214 for each row, and the pixel signal of each pixel 220 in the row is output to the column ADC 230 via the vertical signal line 229 in the row.

The circuit configuration of the pixel 220 is not limited to the configuration illustrated in the figure as long as it can generate a pixel signal.

[Structure example of column ADC]
FIG. 4 is a block diagram showing a configuration example of the column ADC 230 according to the first embodiment of the present technology. In this column ADC 230, an ADC 231 and a latch circuit 235 are arranged for each column. For example, when the number of columns is 2048, the ADC 231 and the latch circuit 235 are arranged 2048 each.

ADC231 converts the analog pixel signal of the corresponding column into a digital signal. Each of the ADCs 231 includes an auto-zero potential generation circuit 410, capacitances 232 and 233, a comparator 420, and a counter 234.

One end of the capacitance 232 is connected to the vertical signal line 229, and the other end is connected to the input terminal of the comparator 420. One end of the capacitance 233 is connected to the DAC 213 and the other end is connected to the input terminal of the comparator 420.

The auto-zero potential generation circuit 410 generates a predetermined auto-zero potential and supplies it to the comparator 420.

A pixel signal from the pixel array unit 214 and a reference signal from the DAC 213 are input to the comparator 420 via the capacitances 232 and 233. Here, the voltage of the pixel signal is defined as the input voltage V _VSL , and the voltage of the reference signal is defined as the reference voltage V _ram . The comparator 420 compares the input voltage _VVSL with the reference voltage _Vramp , and outputs the comparison result to the counter 234.

The counter 234 counts the count value over the period until the comparison result is reversed. The counter 234 outputs a digital signal indicating the count value to the latch circuit 235.

The operation of these comparators 420 and counter 234 is controlled by the timing control circuit 212.

The latch circuit 235 holds the digital signal from the corresponding ADC 231. The latch circuit 235 supplies a digital signal to the signal processing circuit 120 under the control of the horizontal transfer scanning circuit 215.

Although a single slope type ADC consisting of a comparator 420 and a counter 234 is arranged, an ADC other than the single slope type can be arranged if the ADC includes the comparator 420. For example, SARADC (Successive Approximation Register Analog to Digital Converter) can be arranged instead of the single slope type ADC.

Although the ADC is arranged for each column, it is also possible to arrange the ADC for each pixel. In this case, for example, a circuit that generates a time code based on the counter value is arranged outside the pixel array unit, and an ADC composed of a comparator and a data storage unit is arranged for each pixel. Then, the time code when the comparison result is inverted is held in the data storage unit as a digital signal.

[ADC configuration example]
FIG. 5 is a circuit diagram showing a configuration example of an auto-zero potential generation circuit 410 and a comparator 420 in the ADC 231 according to the first embodiment of the present technology. The auto-zero potential generation circuit 410 includes an external current mirror transistor 411, an external pMOS transistor 412, and an external nMOS transistor 413. As the external current mirror transistor 411, for example, a pMOS transistor is used.

Further, the comparator 420 includes current mirror transistors 421 and 422, pMOS transistors 431 to 434, 428, 249, differential transistors 423 and 424, a tail current source 425, and an auto-zero transistor 426. A pMOS transistor is used as the current mirror transistor 421, the current mirror transistor 422, and the auto zero transistor 426. As the differential transistors 423 and 424, nMOS transistors are used.

The current mirror transistors 421 and 422 are connected in parallel to the node of the power supply voltage VDD. Further, the gate of the current mirror transistor 421 is connected to the gate of the current mirror transistor 422 and the gate of the external current mirror transistor 411.

The external pMOS transistor 412 and the external nMOS transistor 413 are connected in series between the external current mirror transistor 411 and the node of the reference voltage (ground voltage, etc.) VSS. The gate of the external pMOS transistor 412 is connected to the node of the reference voltage VSS, and the gate of the external nMOS transistor 413 is connected to its drain. By these connections, both the external pMOS transistor 412 and the external nMOS transistor 413 are turned on.

The pMOS transistor 431 opens and closes the path between the connection node of the current mirror transistor 421 and the differential transistor 423 and the gate of the differential transistor 423 according to the control signal xΦ2 from the timing control circuit 212.

The pMOS transistor 432 opens and closes the path between the gate and drain of the current mirror transistor 421 according to the control signal xΦ7 from the timing control circuit 212.

The pMOS transistor 433 opens and closes the path between the gate and drain of the current mirror transistor 422 according to the control signal xΦ6 from the timing control circuit 212.

The potential of the connection node between the external current mirror transistor 411 and the external pMOS transistor 412 is defined as the auto-zero potential _Vext . The pMOS transistor 428 opens and closes the path between the node of the auto-zero potential Vext and the gate of the differential transistor 423 according to the control signal _xΦ4 from the timing control circuit 212. The pMOS transistor 429 opens and closes the path between the node of the auto-zero potential Vext and the gate of the differential transistor 424 according to the control signal _xΦ3 from the timing control circuit 212.

Further, the gate of the differential transistor 423 is also connected to the capacitance 232 on the vertical signal line 229 side. The drain of the differential transistor 423 is connected to the drain of the current mirror transistor 421.

The gate of the differential transistor 424 is connected to the capacitance 233 on the DAC 213 side. The drain of the differential transistor 424 is connected to the drain of the current mirror transistor 422. The voltage of the connection node of the current mirror transistor 422 and the differential transistor 424 is output to the counter 234 as an output voltage Vout indicating the comparison result.

The tail current source 425 is commonly connected to the sources of the differential transistors 423 and 424. As the tail current source 425, for example, an nMOS transistor is used.

The auto-zero transistor 426 opens and closes the path between the gate and drain of the differential transistor 424 according to the control signal xΦ1. The control signal xΦ1 is supplied by, for example, the timing control circuit 212.

In the above circuit, the current supplied by the tail current source ₄₂₅ is defined as IT. In this case, the external current mirror transistor 411 supplies the IT / 2 current to the external _pMOS transistor 412 and the external nMOS transistor 413, respectively. The gate-source voltage _{VN_TM} of the external nMOS transistor 413 corresponding to this current is expressed by the following equation.
_{VN_TM} = _{VTHN_TM} + ( _IT / _βTM ) ^1/2 ... Equation 1
In the above equation, _{VTHN_TM} is the threshold voltage of the external nMOS transistor 413, and _βTM is a coefficient determined by the size of the transistor, the oxide film capacity, and the like.

Further, the gate-source voltage _{VP_AZM} of the external pMOS transistor 412 according to the current of _IT / 2 is expressed by the following equation.
_{VP_AZM} = V _{THP_AZM} + ( _{IT / β AZM )} ^1/2 ... Equation 2
In the above equation, _{VTHP_AZM} is the threshold voltage of the external pMOS transistor 412, and β _AZM is a coefficient determined by the size of the transistor, the oxide film capacity, and the like.

From the connection configuration in the auto-zero potential generation circuit 410, the higher of the voltage _{VN_TM} and the voltage _{VP_AZM} is output as the auto-zero potential _Vext . Therefore, the auto-zero potential _Vext is expressed by the following equation.

On the other hand, the input range (in other words, the operating range) of the comparator 420 is expressed by the following equation.
V _OV0 + _{VN_dif} <V _ext ... Equation 4
V _ext <VDD-V _OV1- ( _{VP_cur} - _{VN_dif} ) ... Equation 5
In Equation 4, _VOV0 indicates the voltage between the source of the differential transistor 423 and the reference voltage VSS (in other words, the source voltage). _{VN_dim} indicates the gate-source voltage of the differential transistor 423. In Equation 5, _VOV01 represents the drain-source voltage of the differential transistor 423. _{VP_cur} indicates the voltage between the gate and the source of the current mirror transistor 421.

By transforming Equation 4 and substituting Equation 3, the voltage _VOV0 is expressed by the following equation.

In Equation 6, the difference between the voltage _{VN_TM} and the voltage _{VN_dif} corresponds to the difference in the threshold voltage of the external nMOS transistor 413 and the differential transistor 423 if the respective coefficients β are the same. In this case, _the following equation holds when _{VN_TM} > _{VP_AZM} .
V _OV0 <V _{THN_TM} -V _{THN_dif} ... Equation 7
In the above equation, _{VTHN_dim} is the threshold voltage of the differential transistor 423.

From Equation 7, if there is a correlation between the threshold voltages _{VTHN_TM} and _{VTHN_dim} , the dependence on process variation becomes small. However, in order for this effect to occur, it is necessary to satisfy the condition (1) that "the external nMOS transistor 413 is an nMOS transistor having a threshold voltage higher than the differential transistor 423 by _VOV0 or more".

Further, in Equation 6, the difference between the voltage _{VP_AZM} and the voltage _{VN_dif} is premised on the condition that _{VP_AZM} ≧ _{VN_TM} is satisfied. Therefore, if the condition (1) is satisfied, there is a problem. It does not become.

Next, the on-resistance RON of the auto-zero _transistor 426 is expressed by the following equation.
R _ON = 1 / {β _AZ (V _ext -V _{THP_AZ} )} ... Equation 8
In the above equation, _{VTHP_AZ} is the threshold voltage of the auto-zero transistor 426, and β _AZ is a coefficient determined by the size of the transistor, the oxide film capacity, and the like.

From Equation 8, the on-resistance RON is inversely proportional to the auto-zero potential _Vext input to the differential _transistor 423. Therefore, if the auto-zero potential _Vext is set too low in order to widen the operating range, the _on -resistance RON rises and the settling time of auto-zero is extended. Therefore, the auto-zero potential _Vext needs to be determined in consideration of the _on -resistance RON in addition to the operating range of the comparator 420.

Substituting Equation 3 into Equation 8 yields the following equation.

As described above, the polarity of the external pMOS transistor 412 is the same as that of the auto-zero transistor 426. Therefore, from Equation 9, if the threshold voltages of these transistors are the same (that is, _{VTHP_AZM} = _{VTHP_AZ} ), the difference between the voltage _{VP_AZM and the voltage V THP_AZ is} “0”. Further, when _{VP_AZM} > _{VN_TM , the} following equation holds.
R _ON = 1 / [β _AZ {( _{IT / β AZM )} ^1/2 }] ・ ・ ・ Equation 10

Assuming that the coefficients β _AZ and β _AZM are the same, Equation 9 can be replaced with the following equation.
R _ON = 1 / {(β _{AZ IT )} ^1/2 } ・ ・ ・ Equation 11

From Equation 11, it can be said that the dependence of the on-resistance _{RON on} the process variation is small. Further, the on-resistance _RON when _{VP_AZM} ≧ _{VN_TM} is smaller than the value of Equation 11 because it is premised that the condition of _{VP_AZM} ≧ _{VN_TM} is satisfied.

As described above, by setting the auto-zero potential _Vext to a value that fluctuates in the same manner as the auto-zero transistor 426 depending on the variation of the process, as illustrated in Equation 11, the variation of the _on -resistance RON due to the variation. Can be offset.

FIG. 6 is a timing chart showing an example of the operation of the solid-state image sensor 200 according to the first embodiment of the present technology. In the auto-zero period of timings T0 to T1 immediately before the end of exposure, the timing control circuit 212 supplies low-level control signals xΦ1 and xΦ4. The control signals xΦ2 and xΦ3 are set to a high level. Immediately before the timing T0, the timing control circuit 212 sets the control signal xΦ6 to a high level and sets the control signal xΦ7 to a low level, and immediately after the timing T1, sets the control signal xΦ6 to a low level and sets the control signal xΦ7 to a high level. To.

Then, during the P-phase conversion period of the timings T2 to T3, the pixel 220 supplies the reset level as the input voltage _VVSL via the vertical signal line 229. Here, the reset level indicates the level when the pixel 220 is initialized, and is also called the P phase level. During the P-phase conversion period, the DAC 213 gradually increases the level of the reference signal. The reset level (P phase level) is AD converted within this period.

During the D-phase conversion period of timings T4 to T5, the pixel 220 supplies the signal level as an input voltage _VVSL via the vertical signal line 229. Here, the signal level indicates the level when the electric charge is transferred to the floating diffusion layer in the pixel 220, and is also called the D phase level. During the D-phase conversion period, the DAC 213 gradually increases the level of the reference signal. The signal level (D phase level) is AD converted within this period.

Generally, conversion is performed in the order of P phase level and D phase level. The voltage of the vertical signal line tends to be lower at the D phase level than at the P phase level. Therefore, the level (low level) of the control signal xΦ1 at the time of auto zero is set to a relatively high value. For example, the voltage dropped from the power supply voltage VDD by the drain-source voltage of the current mirror transistor connected to the diode is used as the low level of the control signal xΦ1 at auto zero.

The column ADC230 or the circuit in the subsequent stage performs CDS (Correlated Double Sampling) processing for obtaining the difference between the P phase level and the D phase level as a net pixel signal. Hereinafter, the same control is repeatedly executed each time a row is selected.

FIG. 7 is a graph showing an example of the characteristics of the comparator according to the first embodiment of the present technique. In the figure, the vertical axis shows the voltage and the horizontal axis shows the resistance value.

Consider a comparative example in which a fixed auto-zero potential _Vext that does not fluctuate due to process variation is set. In this comparative example, if the auto-zero potential _Vext is set to a value slightly higher than the lower limit of the operating range and the criterion of _on -resistance RON is also satisfied, it seems that there is no problem.

However, in reality, the lower limit of the operating range of the comparator 420 (the left side of Equation 4) may fluctuate depending on the variation in the process. Arrows with "SS" in the figure indicate the range of variation. From Equation 4, the lower limit of the operating range changes (for example, rises) according to the fluctuation of the voltage _{VN_dim} between the gate and the source of the differential transistor 423 due to the variation in the process.

In the comparative example, while the auto-zero potential V _ext does not fluctuate, the lower limit of the operating range fluctuates (rises), so that the auto-zero potential V _ext may deviate from the operating range and the comparator 420 may become unstable. For example, an event in which the inversion of the comparison result of the comparator 420 is significantly delayed or an event in which the inversion is not performed occurs.

Therefore, in the auto-zero potential generation circuit 410, when _{VN_TM} > _{VP_AZM} as exemplified in Equation 3, the fluctuation amount due to _the process variation is the fluctuation amount of the voltage _{VN_dif} between the gate and the source of the differential transistor 423. It supplies substantially the same auto-zero potential V _ext . When the lower limit of the operating range changes (rises) according to the fluctuation of the voltage _{VN_dim} , the auto-zero potential _Vext also fluctuates (rises). As a result, the auto-zero potential V _ext does not go out of the operating range. Therefore, the operation of the comparator 420 can be stabilized. Here, "substantially the same" means that the difference between the two values to be compared is less than a predetermined allowable value.

Further, in the comparative example, the on-resistance _RON may fluctuate depending on the variation of the process. Therefore, in the auto-zero potential generation circuit 410, as illustrated in Equation 3, when _{VN_TM} ≤ _{VP_AZM} , the amount of fluctuation due _to process variation is substantially the same as the amount of fluctuation of the threshold voltage V _{THP_AZM} of the auto-zero transistor 426. The potential _Vext is supplied. Therefore, as illustrated in Equation 10, fluctuations in the _on -resistance RON can be suppressed. As a result, it is possible to prevent a long settling time at the time of auto zero.

As described above, according to the first embodiment of the present technique, the auto-zero potential generation circuit 410 supplies an auto-zero potential in which the amount of fluctuation due to process variation is substantially the same as that of the auto-zero transistor 426, so that the comparator 420 operates. Can be stabilized.

<2. Second Embodiment>
In the first embodiment described above, the pMOS transistor is used as the auto-zero transistor 426, but in this configuration, an external pMOS transistor 412 is required in order to suppress fluctuations in the _on -resistance RON. The solid-state image sensor 200 of the second embodiment is different from the first embodiment in that the number of external pMOS transistors 412 is reduced by using the nMOS transistor as an auto-zero transistor.

FIG. 8 is a circuit diagram showing a configuration example of the auto-zero potential generation circuit 410 and the comparator 420 according to the second embodiment of the present technology. The comparator 420 of the second embodiment differs from the first embodiment in that it includes an nMOS auto-zero transistor 427 instead of the pMOS auto-zero transistor 426. A control signal Φ1 that becomes a high level within the auto-zero period is input to the auto-zero transistor 427.

Further, the auto-zero potential generation circuit 410 of the second embodiment is different from the first embodiment in that the external pMOS transistor 412 is not arranged.

As illustrated in the figure, the equation 8 can be replaced with the following equation by changing the auto-zero transistor to nMOS.
R _ON = 1 / {β _AZ (V _ext -V _{THN_AZ} )} ... Equation 12
In the above equation, _{VTHN_AZ} indicates the threshold voltage of the nMOS transistor.

From Equation 12, the on-resistance _RON also changes according to the fluctuation of the characteristics of the nMOS transistor as well as the operating range. Therefore, unlike the first embodiment, it is not necessary to consider the variation of the pMOS transistor, and the robustness is improved. In particular, it is effective for setting the auto-zero potential _Vext to the limit of the lower limit of the operating range when the on-resistance of the pMOS transistor becomes high.

As described above, according to the second embodiment of the present technique, since the nMOS auto-zero transistor 427 is used, the robustness is improved as compared with the first embodiment in which the external pMOS transistor 412 is required. Can be done.

<3. Third Embodiment>
In the second embodiment described above, the differential transistors 423 and 424 are connected to the current mirror transistors 421 and 422. However, in this configuration, the input offset voltage of the comparator 420 tends to increase when the auto-zero potential _Vext is set to the very limit of the lower limit of the operating range. This is because as the auto-zero potential voltage _decreases , the drain-source voltage of the differential transistor 424 on the lamp side decreases, and the difference from the drain-source voltage of the differential transistor 423 on the input side widens. be. The solid-state image sensor 200 of the third embodiment is different from the second embodiment in that the input offset voltage is reduced by inserting a cascode transistor.

FIG. 9 is a circuit diagram showing a configuration example of the auto-zero potential generation circuit 410 and the comparator 420 according to the third embodiment of the present technology. The auto-zero potential generation circuit 410 of the third embodiment is different from the second embodiment in that it further includes a control transistor 414 and an external nMOS transistor 415.

Further, the comparator 420 of the third embodiment does not include the pMOS transistors 428 and 429, but further includes a pMOS transistor 434, an nMOS transistor 435, 438 and 439, and a cascode transistor 436 and 437. It is different from the embodiment of. Further, a column amplifier 440 is inserted between the comparator 420 and the counter 234 for each column.

The control transistor 414, the external nMOS transistor 415, and the external nMOS transistor 413 are connected in series between the external current mirror transistor 411 and the reference voltage VSS. A control signal Φ5 from the timing control circuit 212 is input to the gate of the control transistor 414.

The connection node of the external current mirror transistor 411 and the control transistor 414 and the gate of the external nMOS transistor 415 are connected to the gate of the cascode transistor 436. Let the voltage of this node be _Vext2 .

The pMOS transistor 431 opens and closes the path between the connection node of the current mirror transistor 421 and the cascode transistor 436 and the gate of the differential transistor 423 according to the control signal xΦ2 from the timing control circuit 212.

The pMOS transistor 434 opens and closes the path between the connection node of the current mirror transistor 422 and the cascode transistor 437 and the gate of the differential transistor 424 according to the control signal xΦ3 from the timing control circuit 212.

The nMOS transistor 435 is inserted between the connection node of the current mirror transistor 421 and the cascode transistor 436 and the gate of the differential transistor 423. A predetermined low level TIEL is input to the gate of the nMOS transistor 435.

A predetermined high level TIEH is input to the gate of the cascode transistor 437.

The nMOS transistor 438 opens and closes the path between the gate of the external nMOS transistor 413 and the gate of the differential transistor 423 according to the control signal Φ4 from the timing control circuit 212.

The nMOS transistor 439 is inserted between the connection node of the external nMOS transistors 413 and 415 and the gate of the differential transistor 424. A predetermined low level TIEL is input to the gate of the nMOS transistor 439.

The column amplifier 440 amplifies the output of the comparator 420 by a predetermined analog gain and supplies it to the counter 234.

It should be noted that the third embodiment can be applied to the first embodiment using the pMOS auto-zero transistor 426. In this case, an external pMOS transistor may be added to the auto-zero potential generation circuit 410, and the control signal xΦ1 may be input to the auto-zero transistor 426.

FIG. 10 is a timing chart showing an example of the operation of the solid-state image sensor 200 according to the third embodiment of the present technology. The control signals xΦ2 and xΦ3 are set to a high level. Immediately before the timing T0, the timing control circuit 212 sets the control signals Φ5 and xΦ6 to the high level and the control signal xΦ7 to the low level.

Then, at the timing T0 at the start of the auto-zero period, the timing control circuit 212 sets the control signals Φ1 and Φ4 to a high level. At the end timing T1 of the auto-zero period, the timing control circuit 212 sets the control signals Φ1 and Φ4 to a low level.

Immediately after the timing T1, the timing control circuit 212 sets the control signals Φ5 and xΦ6 to the low level and the control signal xΦ7 to the high level.

FIG. 11 is a diagram for explaining the effect in the third embodiment of the present technique. A in the figure shows the comparator 420 of the second embodiment. In this second embodiment, the cascode transistor is not inserted between the current mirror circuit (current mirror transistors 421 and 422) and the differential transistors 423 and 424.

If auto-zero is performed as it is, the drain-source voltage of the differential transistor 424 on the lamp side decreases as the auto-zero potential Vext decreases, and the difference from the drain-source voltage of the differential transistor 423 on the input side increases. It will spread. As a result, the input offset voltage of the comparator 420 may increase.

Therefore, in the third embodiment, as illustrated in b in the figure, the timing control circuit 212 turns on the control transistor 414 by the control signal Φ5 and inserts the cascode transistors 436 and 437 within the auto-zero period. ing. Then, when the auto zero is completed, the timing control circuit 212 releases the cascode.

In this way, by cascoding only at the time of auto zero, the drain potentials of the differential transistors 423 and 424 can be made uniform. As a result, it is possible to suppress an increase in the difference between the drain and source voltages of the differential transistors 423 and 424, respectively, and reduce the input offset voltage.

In particular, when analog gain is applied by a column amplifier 440 or the like, an offset on the order of several millivolts (mV) causes a fatal result, so cascode conversion is effective.

As described above, according to the third embodiment of the present technique, the input offset voltage in the comparator 420 can be reduced because the cascode is formed within the auto-zero period.

<4. Fourth Embodiment>
In the first embodiment described above, the auto-zero potential generation circuit 410 is arranged for each column, but in this configuration, the circuit scale of the column ADC 230 increases as the number of columns increases. The solid-state image sensor 200 of the fourth embodiment is different from the first embodiment in that the circuit scale is reduced by sharing the auto-zero potential generation circuit 410 in a plurality of rows.

FIG. 12 is a block diagram showing a configuration example of the column ADC 230 according to the fourth embodiment of the present technology. In the column ADC 230 of the fourth embodiment, one auto-zero potential generation circuit 410 is arranged outside the ADC 231. Then, one auto-zero potential generation circuit 410 is shared by a plurality of columns (for example, all columns).

It is also possible to arrange the auto-zero potential generation circuit 410 for each M (M is an integer of 2 or more) columns, and share one auto-zero potential generation circuit 410 with those M columns.

By sharing the auto-zero potential generation circuit 410 among a plurality of rows, the circuit scale can be reduced as compared with the first embodiment in which the auto-zero potential generation circuit 410 is arranged for each row.

Note that the second and third embodiments can be applied to the fourth embodiment.

As described above, according to the fourth embodiment, since the auto-zero potential generation circuit 410 is shared by a plurality of columns, the circuit scale of the column ADC 230 can be reduced.

<5. Application example to moving body>
The technique according to the present disclosure (the present technique) can be applied to various products. For example, the technology according to the present disclosure is realized as a device mounted on a moving body of any kind such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility, an airplane, a drone, a ship, and a robot. You may.

FIG. 13 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technique according to the present disclosure can be applied.

The vehicle control system 12000 includes a plurality of electronic control units connected via the communication network 12001. In the example shown in FIG. 13, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside information detection unit 12030, an in-vehicle information detection unit 12040, and an integrated control unit 12050. Further, as a functional configuration of the integrated control unit 12050, a microcomputer 12051, an audio image output unit 12052, and an in-vehicle network I / F (interface) 12053 are shown.

The drive system control unit 12010 controls the operation of the device related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 has a driving force generator for generating a driving force of a vehicle such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving force to the wheels, and a steering angle of the vehicle. It functions as a control device such as a steering mechanism for adjusting and a braking device for generating braking force of the vehicle.

The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a keyless entry system, a smart key system, a power window device, or a control device for various lamps such as headlamps, back lamps, brake lamps, turn signals or fog lamps. In this case, the body system control unit 12020 may be input with radio waves transmitted from a portable device that substitutes for the key or signals of various switches. The body system control unit 12020 receives inputs of these radio waves or signals and controls a vehicle door lock device, a power window device, a lamp, and the like.

The vehicle outside information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, the image pickup unit 12031 is connected to the vehicle outside information detection unit 12030. The vehicle outside information detection unit 12030 causes the image pickup unit 12031 to capture an image of the outside of the vehicle and receives the captured image. The vehicle outside information detection unit 12030 may perform object detection processing or distance detection processing such as a person, a vehicle, an obstacle, a sign, or a character on the road surface based on the received image.

The image pickup unit 12031 is an optical sensor that receives light and outputs an electric signal according to the amount of the light received. The image pickup unit 12031 can output an electric signal as an image or can output it as distance measurement information. Further, the light received by the image pickup unit 12031 may be visible light or invisible light such as infrared light.

The in-vehicle information detection unit 12040 detects the in-vehicle information. For example, a driver state detection unit 12041 that detects a driver's state is connected to the vehicle interior information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that images the driver, and the in-vehicle information detection unit 12040 determines the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041. It may be calculated, or it may be determined whether or not the driver has fallen asleep.

The microcomputer 12051 calculates the control target value of the driving force generator, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, and the drive system control unit. A control command can be output to 12010. For example, the microcomputer 12051 realizes ADAS (Advanced Driver Assistance System) functions including vehicle collision avoidance or impact mitigation, follow-up driving based on inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane deviation warning, and the like. It is possible to perform cooperative control for the purpose of.

Further, the microcomputer 12051 controls the driving force generating device, the steering mechanism, the braking device, and the like based on the information around the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040. It is possible to perform coordinated control for the purpose of automatic driving that runs autonomously without depending on the operation.

Further, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the vehicle outside information detection unit 12030. For example, the microcomputer 12051 controls the headlamps according to the position of the preceding vehicle or the oncoming vehicle detected by the outside information detection unit 12030, and performs cooperative control for the purpose of anti-glare such as switching the high beam to the low beam. It can be carried out.

The audio image output unit 12052 transmits an output signal of at least one of audio and an image to an output device capable of visually or audibly notifying information to the passenger or the outside of the vehicle. In the example of FIG. 13, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as output devices. The display unit 12062 may include, for example, at least one of an onboard display and a head-up display.

FIG. 14 is a diagram showing an example of the installation position of the imaging unit 12031.

In FIG. 14, as the imaging unit 12031, the imaging unit 12101, 12102, 12103, 12104, 12105 is provided.

The image pickup units 12101, 12102, 12103, 12104, 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumpers, back doors, and the upper part of the windshield in the vehicle interior of the vehicle 12100. The image pickup unit 12101 provided on the front nose and the image pickup section 12105 provided on the upper part of the windshield in the vehicle interior mainly acquire an image in front of the vehicle 12100. The image pickup units 12102 and 12103 provided in the side mirror mainly acquire images of the side of the vehicle 12100. The image pickup unit 12104 provided in the rear bumper or the back door mainly acquires an image of the rear of the vehicle 12100. The image pickup unit 12105 provided on the upper part of the front glass in the vehicle interior is mainly used for detecting a preceding vehicle, a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

Note that FIG. 14 shows an example of the shooting range of the imaging units 12101 to 12104. The imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, the imaging ranges 12112 and 12113 indicate the imaging range of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and the imaging range 12114 indicates the imaging range. The imaging range of the imaging unit 12104 provided on the rear bumper or the back door is shown. For example, by superimposing the image data captured by the imaging units 12101 to 12104, a bird's-eye view image of the vehicle 12100 can be obtained.

At least one of the image pickup units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image pickup units 12101 to 12104 may be a stereo camera including a plurality of image pickup elements, or may be an image pickup element having pixels for phase difference detection.

For example, the microcomputer 12051 has a distance to each three-dimensional object in the image pickup range 12111 to 12114 based on the distance information obtained from the image pickup unit 12101 to 12104, and a temporal change of this distance (relative speed with respect to the vehicle 12100). By obtaining can. Further, the microcomputer 12051 can set an inter-vehicle distance to be secured in advance in front of the preceding vehicle, and can perform automatic brake control (including follow-up stop control), automatic acceleration control (including follow-up start control), and the like. In this way, it is possible to perform coordinated control for the purpose of automatic driving or the like that autonomously travels without relying on the driver's operation.

For example, the microcomputer 12051 converts three-dimensional object data related to a three-dimensional object into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, electric poles, and other three-dimensional objects based on the distance information obtained from the image pickup units 12101 to 12104. It can be classified and extracted and used for automatic avoidance of obstacles. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. Then, the microcomputer 12051 determines the collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or higher than the set value and there is a possibility of collision, the microcomputer 12051 via the audio speaker 12061 or the display unit 12062. By outputting an alarm to the driver and performing forced deceleration and avoidance steering via the drive system control unit 12010, driving support for collision avoidance can be provided.

At least one of the image pickup units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the captured image of the imaging unit 12101 to 12104. Such recognition of a pedestrian is, for example, a procedure for extracting feature points in an image captured by an image pickup unit 12101 to 12104 as an infrared camera, and pattern matching processing is performed on a series of feature points indicating the outline of an object to determine whether or not the pedestrian is a pedestrian. It is done by the procedure to determine. When the microcomputer 12051 determines that a pedestrian is present in the captured image of the image pickup unit 12101 to 12104 and recognizes the pedestrian, the audio image output unit 12052 determines the square contour line for emphasizing the recognized pedestrian. The display unit 12062 is controlled so as to superimpose and display. Further, the audio image output unit 12052 may control the display unit 12062 so as to display an icon or the like indicating a pedestrian at a desired position.

The above is an example of a vehicle control system to which the technique according to the present disclosure can be applied. The technique according to the present disclosure can be applied to, for example, the image pickup unit 12031 among the configurations described above. Specifically, the image pickup apparatus 100 of FIG. 1 can be applied to the image pickup unit 12031. By applying the technique according to the present disclosure to the image pickup unit 12031, it is possible to stabilize the operation of the comparator in the solid-state image pickup device and improve the reliability of the system.

<6. Application example to endoscopic surgery system>
The technique according to the present disclosure can be applied to various products. For example, the techniques according to the present disclosure may be applied to an endoscopic surgery system.

FIG. 15 is a diagram showing an example of a schematic configuration of an endoscopic surgery system 5000 to which the technique according to the present disclosure can be applied. FIG. 15 illustrates a surgeon (doctor) 5067 performing surgery on patient 5071 on patient bed 5069 using the endoscopic surgery system 5000. As shown in the figure, the endoscopic surgery system 5000 includes an endoscope 5001, other surgical tools 5017, a support arm device 5027 for supporting the endoscope 5001, and various devices for endoscopic surgery. It is composed of a cart 5037 and a cart 5037.

In endoscopic surgery, instead of cutting the abdominal wall to open the abdomen, multiple tubular opening devices called trocca 5025a to 5025d are punctured into the abdominal wall. Then, from the trocca 5025a to 5025d, the lens barrel 5003 of the endoscope 5001 and other surgical tools 5017 are inserted into the body cavity of the patient 5071. In the illustrated example, as other surgical tools 5017, a pneumoperitoneum tube 5019, an energy treatment tool 5021 and forceps 5023 are inserted into the body cavity of patient 5071. Further, the energy treatment tool 5021 is a treatment tool for incising and peeling a tissue, sealing a blood vessel, or the like by using a high frequency current or ultrasonic vibration. However, the surgical tool 5017 shown is only an example, and as the surgical tool 5017, various surgical tools generally used in endoscopic surgery such as a sword and a retractor may be used.

The image of the surgical site in the body cavity of the patient 5071 taken by the endoscope 5001 is displayed on the display device 5041. The surgeon 5067 performs a procedure such as excising the affected area by using the energy treatment tool 5021 or the forceps 5023 while viewing the image of the surgical site displayed on the display device 5041 in real time. Although not shown, the pneumoperitoneum tube 5019, the energy treatment tool 5021, and the forceps 5023 are supported by the operator 5067, an assistant, or the like during the operation.

(Support arm device)
The support arm device 5027 includes an arm portion 5031 extending from the base portion 5029. In the illustrated example, the arm portion 5031 is composed of joint portions 5033a, 5033b, 5033c, and links 5035a, 5035b, and is driven by control from the arm control device 5045. The endoscope 5001 is supported by the arm portion 5031, and its position and posture are controlled. Thereby, the stable position fixing of the endoscope 5001 can be realized.

(Endoscope)
The endoscope 5001 is composed of a lens barrel 5003 in which a region having a predetermined length from the tip is inserted into the body cavity of the patient 5071, and a camera head 5005 connected to the base end of the lens barrel 5003. In the illustrated example, the endoscope 5001 configured as a so-called rigid mirror having a rigid barrel 5003 is illustrated, but the endoscope 5001 is configured as a so-called flexible mirror having a flexible barrel 5003. May be good.

An opening in which an objective lens is fitted is provided at the tip of the lens barrel 5003. A light source device 5043 is connected to the endoscope 5001, and the light generated by the light source device 5043 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 5003, and is an objective. It is irradiated toward the observation target in the body cavity of the patient 5071 through the lens. The endoscope 5001 may be a direct endoscope, a perspective mirror, or a side endoscope.

An optical system and an image pickup element are provided inside the camera head 5005, and the reflected light (observation light) from the observation target is focused on the image pickup element by the optical system. The observation light is photoelectrically converted by the image pickup device, and an electric signal corresponding to the observation light, that is, an image signal corresponding to the observation image is generated. The image signal is transmitted to the camera control unit (CCU: Camera Control Unit) 5039 as RAW data. The camera head 5005 is equipped with a function of adjusting the magnification and the focal length by appropriately driving the optical system thereof.

Note that, for example, in order to support stereoscopic viewing (3D display) and the like, the camera head 5005 may be provided with a plurality of image pickup elements. In this case, a plurality of relay optical systems are provided inside the lens barrel 5003 in order to guide the observation light to each of the plurality of image pickup elements.

(Various devices mounted on the cart)
The CCU 5039 is composed of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and the like, and comprehensively controls the operations of the endoscope 5001 and the display device 5041. Specifically, the CCU 5039 performs various image processing for displaying an image based on the image signal, such as a development process (demosaic process), on the image signal received from the camera head 5005. The CCU 5039 provides the image signal subjected to the image processing to the display device 5041. Further, the CCU 5039 transmits a control signal to the camera head 5005 and controls the driving thereof. The control signal may include information about imaging conditions such as magnification and focal length.

The display device 5041 displays an image based on the image signal processed by the CCU 5039 under the control of the CCU 5039. When the endoscope 5001 is compatible with high-resolution shooting such as 4K (horizontal number of pixels 3840 x vertical pixel number 2160) or 8K (horizontal pixel number 7680 x vertical pixel number 4320), and / or 3D display. In the case of the display device 5041, a display device capable of displaying a high resolution and / or a device capable of displaying in 3D can be used corresponding to each of the display devices 5041. When a display device 5041 having a size of 55 inches or more is used for high-resolution shooting such as 4K or 8K, a further immersive feeling can be obtained. Further, a plurality of display devices 5041 having different resolutions and sizes may be provided depending on the application.

The light source device 5043 is composed of, for example, a light source such as an LED (light emission diode), and supplies irradiation light for photographing the surgical site to the endoscope 5001.

The arm control device 5045 is configured by a processor such as a CPU, and operates according to a predetermined program to control the drive of the arm portion 5031 of the support arm device 5027 according to a predetermined control method.

The input device 5047 is an input interface for the endoscopic surgery system 5000. The user can input various information and input instructions to the endoscopic surgery system 5000 via the input device 5047. For example, the user inputs various information related to the surgery, such as physical information of the patient and information about the surgical procedure, via the input device 5047. Further, for example, the user is instructed to drive the arm portion 5031 via the input device 5047, or is instructed to change the imaging conditions (type of irradiation light, magnification, focal length, etc.) by the endoscope 5001. , Instructions to drive the energy treatment tool 5021, etc. are input.

The type of the input device 5047 is not limited, and the input device 5047 may be various known input devices. As the input device 5047, for example, a mouse, a keyboard, a touch panel, a switch, a foot switch 5057 and / or a lever and the like can be applied. When a touch panel is used as the input device 5047, the touch panel may be provided on the display surface of the display device 5041.

Alternatively, the input device 5047 is a device worn by the user, such as a glasses-type wearable device or an HMD (Head Mounted Display), and various inputs are made according to the user's gesture and line of sight detected by these devices. Is done. Further, the input device 5047 includes a camera capable of detecting the movement of the user, and various inputs are performed according to the gesture and the line of sight of the user detected from the image captured by the camera. Further, the input device 5047 includes a microphone capable of picking up the voice of the user, and various inputs are performed by voice via the microphone. In this way, the input device 5047 is configured to be able to input various information in a non-contact manner, so that a user who belongs to a clean area (for example, an operator 5067) can operate a device belonging to the unclean area in a non-contact manner. Is possible. In addition, the user can operate the device without taking his / her hand off the surgical tool that he / she has, which improves the convenience of the user.

The treatment tool control device 5049 controls the drive of the energy treatment tool 5021 for cauterizing tissue, incising, sealing a blood vessel, or the like. The pneumoperitoneum device 5051 gas in the body cavity of the patient 5071 via the pneumoperitoneum tube 5019 in order to inflate the body cavity of the patient 5071 for the purpose of securing the field of view by the endoscope 5001 and securing the work space of the operator. Is sent. The recorder 5053 is a device capable of recording various information related to surgery. The printer 5055 is a device capable of printing various information related to surgery in various formats such as text, images, and graphs.

Hereinafter, a particularly characteristic configuration of the endoscopic surgery system 5000 will be described in more detail.

(Support arm device)
The support arm device 5027 includes a base portion 5029 as a base and an arm portion 5031 extending from the base portion 5029. In the illustrated example, the arm portion 5031 is composed of a plurality of joint portions 5033a, 5033b, 5033c and a plurality of links 5035a, 5035b connected by the joint portions 5033b, but in FIG. 15, for the sake of simplicity. , The configuration of the arm portion 5031 is simplified and shown. Actually, the shapes, numbers and arrangements of the joint portions 5033a to 5033c and the links 5035a and 5035b, the direction of the rotation axis of the joint portions 5033a to 5033c, and the like are appropriately set so that the arm portion 5031 has a desired degree of freedom. obtain. For example, the arm portion 5031 may be preferably configured to have more than 6 degrees of freedom. As a result, the endoscope 5001 can be freely moved within the movable range of the arm portion 5031, so that the lens barrel 5003 of the endoscope 5001 can be inserted into the body cavity of the patient 5071 from a desired direction. It will be possible.

An actuator is provided in the joint portions 5033a to 5033c, and the joint portions 5033a to 5033c are configured to be rotatable around a predetermined rotation axis by driving the actuator. By controlling the drive of the actuator by the arm control device 5045, the rotation angles of the joint portions 5033a to 5033c are controlled, and the drive of the arm portion 5031 is controlled. Thereby, control of the position and posture of the endoscope 5001 can be realized. At this time, the arm control device 5045 can control the drive of the arm unit 5031 by various known control methods such as force control or position control.

For example, when the operator 5067 appropriately inputs an operation via the input device 5047 (including the foot switch 5057), the drive of the arm unit 5031 is appropriately controlled by the arm control device 5045 according to the operation input. The position and orientation of the endoscope 5001 may be controlled. By this control, the endoscope 5001 at the tip of the arm portion 5031 can be moved from an arbitrary position to an arbitrary position, and then fixedly supported at the moved position. The arm portion 5031 may be operated by a so-called master slave method. In this case, the arm portion 5031 can be remotely controlled by the user via an input device 5047 installed at a location away from the operating room.

When force control is applied, the arm control device 5045 receives an external force from the user, and the actuators of the joint portions 5033a to 5033c are arranged so that the arm portion 5031 moves smoothly according to the external force. So-called power assist control for driving may be performed. As a result, when the user moves the arm portion 5031 while directly touching the arm portion 5031, the arm portion 5031 can be moved with a relatively light force. Therefore, the endoscope 5001 can be moved more intuitively and with a simpler operation, and the convenience of the user can be improved.

Here, in general, in endoscopic surgery, the endoscope 5001 was supported by a doctor called a scopist. On the other hand, by using the support arm device 5027, the position of the endoscope 5001 can be more reliably fixed without human intervention, so that an image of the surgical site can be stably obtained. , It becomes possible to perform surgery smoothly.

The arm control device 5045 does not necessarily have to be provided on the cart 5037. Further, the arm control device 5045 does not necessarily have to be one device. For example, the arm control device 5045 may be provided at each of the joint portions 5033a to 5033c of the arm portion 5031 of the support arm device 5027, and the plurality of arm control devices 5045 cooperate with each other to drive the arm portion 5031. Control may be realized.

(Light source device)
The light source device 5043 supplies the endoscope 5001 with irradiation light for photographing the surgical site. The light source device 5043 is composed of, for example, an LED, a laser light source, or a white light source composed of a combination thereof. At this time, when the white light source is configured by the combination of the RGB laser light sources, the output intensity and the output timing of each color (each wavelength) can be controlled with high accuracy, so that the white balance of the captured image in the light source device 5043 can be controlled. Can be adjusted. Further, in this case, the laser light from each of the RGB laser light sources is irradiated to the observation target in a time-division manner, and the drive of the image sensor of the camera head 5005 is controlled in synchronization with the irradiation timing to correspond to each of RGB. It is also possible to capture the image in a time-division manner. According to this method, a color image can be obtained without providing a color filter in the image pickup device.

Further, the drive of the light source device 5043 may be controlled so as to change the intensity of the output light at predetermined time intervals. By controlling the drive of the image sensor of the camera head 5005 in synchronization with the timing of the change of the light intensity to acquire an image in time division and synthesizing the image, so-called high dynamic without blackout and overexposure. Range images can be generated.

Further, the light source device 5043 may be configured to be able to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, by utilizing the wavelength dependence of light absorption in body tissue, the surface layer of the mucous membrane is irradiated with light in a narrower band than the irradiation light (that is, white light) during normal observation. So-called narrow band imaging, in which a predetermined tissue such as a blood vessel is photographed with high contrast, is performed. Alternatively, in special light observation, fluorescence observation may be performed in which an image is obtained by fluorescence generated by irradiating with excitation light. In fluorescence observation, the body tissue is irradiated with excitation light to observe the fluorescence from the body tissue (autofluorescence observation), or a reagent such as indocyanine green (ICG) is locally injected into the body tissue and the body tissue is injected. It is possible to obtain a fluorescence image by irradiating the excitation light corresponding to the fluorescence wavelength of the reagent. The light source device 5043 may be configured to be capable of supplying narrowband light and / or excitation light corresponding to such special light observation.

(Camera head and CCU)
The functions of the camera head 5005 and the CCU 5039 of the endoscope 5001 will be described in more detail with reference to FIG. FIG. 16 is a block diagram showing an example of the functional configuration of the camera head 5005 and CCU5039 shown in FIG.

Referring to FIG. 16, the camera head 5005 has a lens unit 5007, an image pickup unit 5009, a drive unit 5011, a communication unit 5013, and a camera head control unit 5015 as its functions. Further, the CCU 5039 has a communication unit 5059, an image processing unit 5061, and a control unit 5063 as its functions. The camera head 5005 and the CCU 5039 are bidirectionally connected by a transmission cable 5065 so as to be communicable.

First, the functional configuration of the camera head 5005 will be described. The lens unit 5007 is an optical system provided at a connection portion with the lens barrel 5003. The observation light taken in from the tip of the lens barrel 5003 is guided to the camera head 5005 and incident on the lens unit 5007. The lens unit 5007 is configured by combining a plurality of lenses including a zoom lens and a focus lens. The optical characteristics of the lens unit 5007 are adjusted so as to collect the observation light on the light receiving surface of the image pickup element of the image pickup unit 5009. Further, the zoom lens and the focus lens are configured so that their positions on the optical axis can be moved in order to adjust the magnification and the focus of the captured image.

The image pickup unit 5009 is composed of an image pickup element and is arranged after the lens unit 5007. The observation light that has passed through the lens unit 5007 is focused on the light receiving surface of the image pickup device, and an image signal corresponding to the observation image is generated by photoelectric conversion. The image signal generated by the image pickup unit 5009 is provided to the communication unit 5013.

As the image sensor constituting the image pickup unit 5009, for example, a CMOS (Complementary Metal Oxide Semiconductor) type image sensor having a Bayer array and capable of color photographing is used. As the image pickup device, for example, an image pickup device capable of capturing a high-resolution image of 4K or higher may be used. By obtaining the image of the surgical site with high resolution, the surgeon 5067 can grasp the state of the surgical site in more detail, and the operation can proceed more smoothly.

Further, the image pickup elements constituting the image pickup unit 5009 are configured to have a pair of image pickup elements for acquiring image signals for the right eye and the left eye corresponding to 3D display, respectively. The 3D display enables the surgeon 5067 to more accurately grasp the depth of the living tissue in the surgical site. When the image pickup unit 5009 is composed of a multi-plate type, a plurality of lens units 5007 are also provided corresponding to each image pickup element.

Further, the image pickup unit 5009 does not necessarily have to be provided on the camera head 5005. For example, the image pickup unit 5009 may be provided inside the lens barrel 5003 immediately after the objective lens.

The drive unit 5011 is composed of an actuator, and the zoom lens and the focus lens of the lens unit 5007 are moved by a predetermined distance along the optical axis under the control of the camera head control unit 5015. As a result, the magnification and focus of the image captured by the image pickup unit 5009 can be adjusted as appropriate.

The communication unit 5013 is composed of a communication device for transmitting and receiving various information to and from the CCU 5039. The communication unit 5013 transmits the image signal obtained from the image pickup unit 5009 as RAW data to the CCU 5039 via the transmission cable 5065. At this time, in order to display the captured image of the surgical site with low latency, it is preferable that the image signal is transmitted by optical communication. At the time of surgery, the surgeon 5067 performs the surgery while observing the condition of the affected area with the captured image, so for safer and more reliable surgery, the moving image of the surgical site is displayed in real time as much as possible. This is because it is required. When optical communication is performed, the communication unit 5013 is provided with a photoelectric conversion module that converts an electric signal into an optical signal. The image signal is converted into an optical signal by the photoelectric conversion module, and then transmitted to the CCU 5039 via the transmission cable 5065.

Further, the communication unit 5013 receives a control signal for controlling the drive of the camera head 5005 from the CCU 5039. The control signal includes, for example, information to specify the frame rate of the captured image, information to specify the exposure value at the time of imaging, and / or information to specify the magnification and focus of the captured image. Contains information about the condition. The communication unit 5013 provides the received control signal to the camera head control unit 5015. The control signal from the CCU 5039 may also be transmitted by optical communication. In this case, the communication unit 5013 is provided with a photoelectric conversion module that converts an optical signal into an electric signal, and the control signal is converted into an electric signal by the photoelectric conversion module and then provided to the camera head control unit 5015.

The image pickup conditions such as the frame rate, exposure value, magnification, and focus are automatically set by the control unit 5063 of the CCU 5039 based on the acquired image signal. That is, the so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function are mounted on the endoscope 5001.

The camera head control unit 5015 controls the drive of the camera head 5005 based on the control signal from the CCU 5039 received via the communication unit 5013. For example, the camera head control unit 5015 controls the drive of the image pickup element of the image pickup unit 5009 based on the information to specify the frame rate of the image pickup image and / or the information to specify the exposure at the time of image pickup. Further, for example, the camera head control unit 5015 appropriately moves the zoom lens and the focus lens of the lens unit 5007 via the drive unit 5011 based on the information that the magnification and the focus of the captured image are specified. The camera head control unit 5015 may further have a function of storing information for identifying the lens barrel 5003 and the camera head 5005.

By arranging the configuration of the lens unit 5007, the image pickup unit 5009, and the like in a sealed structure having high airtightness and waterproofness, the camera head 5005 can be made resistant to autoclave sterilization.

Next, the functional configuration of CCU5039 will be described. The communication unit 5059 is configured by a communication device for transmitting and receiving various information to and from the camera head 5005. The communication unit 5059 receives an image signal transmitted from the camera head 5005 via the transmission cable 5065. At this time, as described above, the image signal can be suitably transmitted by optical communication. In this case, corresponding to optical communication, the communication unit 5059 is provided with a photoelectric conversion module that converts an optical signal into an electric signal. The communication unit 5059 provides the image processing unit 5061 with an image signal converted into an electric signal.

Further, the communication unit 5059 transmits a control signal for controlling the drive of the camera head 5005 to the camera head 5005. The control signal may also be transmitted by optical communication.

The image processing unit 5061 performs various image processing on the image signal which is the RAW data transmitted from the camera head 5005. The image processing includes, for example, development processing, high image quality processing (band enhancement processing, super-resolution processing, NR (Noise reduction) processing and / or camera shake correction processing, etc.), and / or enlargement processing (electronic zoom processing). Etc., various known signal processing is included. In addition, the image processing unit 5061 performs detection processing on the image signal for performing AE, AF, and AWB.

The image processing unit 5061 is composed of a processor such as a CPU or GPU, and the processor operates according to a predetermined program, so that the above-mentioned image processing and detection processing can be performed. When the image processing unit 5061 is composed of a plurality of GPUs, the image processing unit 5061 appropriately divides the information related to the image signal and performs image processing in parallel by the plurality of GPUs.

The control unit 5063 performs various controls regarding the imaging of the surgical site by the endoscope 5001 and the display of the captured image. For example, the control unit 5063 generates a control signal for controlling the drive of the camera head 5005. At this time, when the imaging condition is input by the user, the control unit 5063 generates a control signal based on the input by the user. Alternatively, when the endoscope 5001 is equipped with an AE function, an AF function, and an AWB function, the control unit 5063 has an optimum exposure value, a focal length, and an optimum exposure value according to the result of detection processing by the image processing unit 5061. The white balance is calculated appropriately and a control signal is generated.

Further, the control unit 5063 causes the display device 5041 to display the image of the surgical unit based on the image signal processed by the image processing unit 5061. At this time, the control unit 5063 recognizes various objects in the surgical unit image by using various image recognition techniques. For example, the control unit 5063 detects a surgical tool such as forceps, a specific biological part, bleeding, a mist when using the energy treatment tool 5021, etc. by detecting the shape, color, etc. of the edge of the object included in the surgical site image. Can be recognized. When displaying the image of the surgical site on the display device 5041, the control unit 5063 uses the recognition result to superimpose and display various surgical support information on the image of the surgical site. By superimposing the surgery support information and presenting it to the surgeon 5067, it becomes possible to proceed with the surgery more safely and surely.

The transmission cable 5065 connecting the camera head 5005 and the CCU 5039 is an electric signal cable compatible with electric signal communication, an optical fiber compatible with optical communication, or a composite cable thereof.

Here, in the illustrated example, the communication is performed by wire using the transmission cable 5065, but the communication between the camera head 5005 and the CCU 5039 may be performed wirelessly. When the communication between the two is performed wirelessly, it is not necessary to lay the transmission cable 5065 in the operating room, so that the situation where the movement of the medical staff in the operating room is hindered by the transmission cable 5065 can be solved.

The above is an example of an endoscopic surgery system 5000 to which the technique according to the present disclosure can be applied. Although the endoscopic surgery system 5000 has been described here as an example, the system to which the technique according to the present disclosure can be applied is not limited to such an example. For example, the techniques according to the present disclosure may be applied to a flexible endoscopic system for examination or a microsurgery system.

The technique according to the present disclosure can be suitably applied to the imaging unit 5009 among the configurations described above. Specifically, the image pickup apparatus 100 of FIG. 1 can be applied to the image pickup unit 5009. By applying the technique according to the present disclosure to the image pickup unit 5009, the operation of the comparator in the solid-state image pickup device is stabilized, and the reliability of the system is improved.

It should be noted that the above-described embodiment shows an example for embodying the present technology, and the matters in the embodiment and the matters specifying the invention within the scope of claims have a corresponding relationship with each other. Similarly, the matters specifying the invention within the scope of claims and the matters in the embodiment of the present technology having the same name have a corresponding relationship with each other. However, the present technique is not limited to the embodiment, and can be embodied by applying various modifications to the embodiment without departing from the gist thereof.

It should be noted that the effects described in the present specification are merely examples and are not limited, and other effects may be obtained.

The present technology can have the following configurations.
(1) A pair of differential transistors that amplify the difference between the input voltage and a predetermined reference voltage, and
An auto-zero transistor that opens and closes the path between one gate and drain of the pair of differential transistors,
Equipped with an auto-zero potential generation circuit that generates an auto-zero potential whose fluctuation amount due to process variation is substantially the same as the fluctuation amount of the gate-source voltage of the differential transistor and supplies it to the other gate of the pair of differential transistors. Solid-state imaging device.
(2) The auto-zero transistor is a pMOS (p-channel Metal Oxide Semiconductor) transistor.
The pair of differential transistors are nMOS (n-channel MOS) transistors.
The auto-zero potential generation circuit is
With an external pMOS transistor in the ON state,
An external nMOS transistor in the ON state and
The solid-state image pickup device according to (1) above, which includes the external pMOS transistor and an external current mirror transistor that supplies a current to the external nMOS transistor.
(3) The auto-zero transistor and the pair of differential transistors are nMOS transistors.
The auto-zero potential generation circuit is
An external nMOS transistor in the ON state and
The solid-state image pickup device according to (1) above, which includes an external current mirror transistor that supplies a current to the external nMOS transistor.
(4) Current mirror circuit and
Further, a pair of cascode transistors inserted between the pair of differential transistors and the current mirror circuit is provided.
The solid-state image pickup device according to any one of (1) to (3) above, wherein the auto-zero potential generation circuit controls one of the pair of cascode transistors to be turned on within a predetermined auto-zero period.
(5) A pixel array unit in which a plurality of pixels are arranged in a two-dimensional lattice is further provided.
The solid-state image pickup device according to any one of (1) to (4), wherein the comparator including the pair of differential transistors and the auto-zero transistor is arranged for each row of the pixel array unit.
(6) The solid-state image pickup device according to (5) above, wherein the auto-zero potential generation circuit is arranged in each row.
(7) The solid-state imaging device according to (5) above, wherein the auto-zero potential generation circuit is shared by each comparator in a plurality of rows.
(8) A pair of differential transistors that amplify the difference between the input voltage and the predetermined reference voltage and output it as a pixel signal.
An auto-zero transistor that opens and closes the path between one gate and drain of the pair of differential transistors,
An auto-zero potential generation circuit that generates an auto-zero potential whose fluctuation amount due to process variation is substantially the same as the fluctuation amount between the gate and source of the differential transistor and supplies it to the other gate of the pair of differential transistors.
An image pickup apparatus including a signal processing circuit for processing image data in which pixel signals are arranged.

100 Image sensor 110 Optical system 120 Signal processing circuit 130 Memory 140 Monitor 200 Solid-state image sensor 211 Vertical scanning circuit 212 Timing control circuit 213 DAC
214 Pixel array part 215 Horizontal transfer scanning circuit 220 Pixel 221 Photoelectric conversion element 222 Transfer transistor 223 Reset transistor 224 Floating diffusion layer 225 Amplification transistor 226 Selective transistor 230 Column ADC
231 ADC
232, 233 Capacity 234 Counter 235 Latch circuit 410 Auto zero potential generation circuit 411 External current mirror transistor 412 External pMOS transistor 413, 415 External nMOS transistor 414 Control transistor 420 Comparer 421, 422 Current mirror transistor 423, 424 Differential transistor 425 Tail current Source 426, 427 Auto-zero transistor 431 to 434 pMOS transistor 435, 438, 439 nMOS transistor 436, 437 Cascode transistor 440 Column amplifier 5009, 12031 Imaging unit

Claims (8)

1. A pair of differential transistors that amplify the difference between the input voltage and a given reference voltage,
   An auto-zero transistor that opens and closes the path between one gate and drain of the pair of differential transistors,
   Equipped with an auto-zero potential generation circuit that generates an auto-zero potential whose fluctuation amount due to process variation is substantially the same as the fluctuation amount of the gate-source voltage of the differential transistor and supplies it to the other gate of the pair of differential transistors. Solid-state imaging device.
2. The auto-zero transistor is a pMOS (p-channel Metal Oxide Semiconductor) transistor.
   The pair of differential transistors are nMOS (n-channel MOS) transistors.
   The auto-zero potential generation circuit is
   With an external pMOS transistor in the ON state,
   An external nMOS transistor in the ON state and
   The solid-state image sensor according to claim 1, further comprising the external pMOS transistor and an external current mirror transistor that supplies a current to the external nMOS transistor.
3. The auto-zero transistor and the pair of differential transistors are nMOS transistors.
   The auto-zero potential generation circuit is
   An external nMOS transistor in the ON state and
   The solid-state image sensor according to claim 1, further comprising an external current mirror transistor that supplies a current to the external nMOS transistor.
4. With the current mirror circuit,
   Further, a pair of cascode transistors inserted between the pair of differential transistors and the current mirror circuit is provided.
   The solid-state image pickup device according to claim 1, wherein the auto-zero potential generation circuit controls one of the pair of cascode transistors to be turned on within a predetermined auto-zero period.
5. It further includes a pixel array unit in which a plurality of pixels are arranged in a two-dimensional grid pattern.
   The solid-state image sensor according to claim 1, wherein the comparator including the pair of differential transistors and the auto-zero transistor is arranged for each row of the pixel array unit.
6. The solid-state imaging device according to claim 5, wherein the auto-zero potential generation circuit is arranged for each of the columns.
7. The solid-state imaging device according to claim 5, wherein the auto-zero potential generation circuit is shared by each comparator in a plurality of rows.
8. A pair of differential transistors that amplify the difference between the input voltage and a predetermined reference voltage and output it as a pixel signal.
   An auto-zero transistor that opens and closes the path between one gate and drain of the pair of differential transistors,
   An auto-zero potential generation circuit that generates an auto-zero potential whose fluctuation amount due to process variation is substantially the same as the fluctuation amount between the gate and source of the differential transistor and supplies it to the other gate of the pair of differential transistors.
   An image pickup apparatus including a signal processing circuit for processing image data in which pixel signals are arranged.

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