Imaging element and imaging device

Abstract

An imaging element according to an embodiment of the present disclosure includes a plurality of sensor pixels and a voltage control unit. Each of the sensor pixels includes a photoelectric conversion unit and a readout circuit that outputs a pixel signal based on the charge output from the photoelectric conversion unit. The voltage control unit applies a control voltage based on the pixel signal to the plurality of photoelectric conversion units.

Description

Technical Field

[0001] The present disclosure relates to an imaging element and an imaging device. Background Art

[0002] In recent years, imaging elements (infrared sensors) sensitive to the infrared region have been commercialized. For example, Patent Document 1 describes the use of III-V semiconductors such as InGaAs (indium gallium arsenide) as a photoelectric conversion unit for such an infrared sensor. In the photoelectric conversion unit, infrared rays are absorbed to generate electric charges.

[0003] Citation list

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. WO 2017 / 150167 Summary of the invention

[0006] Such an imaging element is expected to suppress degradation in image quality. Therefore, it is expected to provide an imaging element and an imaging device capable of suppressing degradation in image quality.

[0007] An imaging element according to an embodiment of the present disclosure includes a plurality of sensor pixels and a voltage control unit. Each of the sensor pixels includes a photoelectric conversion unit and a readout circuit that outputs a pixel signal based on the charge output from the photoelectric conversion unit. The voltage control unit applies a control voltage based on the pixel signal to each photoelectric conversion unit.

[0008] An imaging device according to an embodiment of the present disclosure includes an imaging element and an image quality control circuit. The imaging element includes a plurality of sensor pixels. Each of the sensor pixels includes a photoelectric conversion unit and a readout circuit that outputs a pixel signal based on the charge output from the photoelectric conversion unit. The image quality control circuit applies a control voltage based on the pixel signal to each photoelectric conversion unit.

[0009] In the imaging element and the imaging device according to each embodiment of the present disclosure, a control voltage based on a pixel signal is applied to each photoelectric conversion unit. This allows the image quality of the image data obtained by the imaging element to be controlled, thereby enabling image quality adjustment to be performed according to the brightness of the image data, compared to the case where a fixed voltage is applied to each photoelectric conversion unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic configuration example of an imaging element according to a first embodiment of the present disclosure is shown.

[0011] Figure 2 Shows Figure 1 An example of a circuit configuration of a sensor pixel.

[0012] Figure 3 Shows Figure 1 An example of a perspective structure of an imaging element.

[0013] Figure 4 Shows Figure 3 An example of a cross-sectional structure of an imaging element.

[0014] Figure 5 (A) shows Figure 1 An example of the relationship between the membrane voltage of an imaging element and the charge that can be held. Figure 5 (B) shows an example of the relationship between the analog range of the ADC and the amplitude of the pixel signal.

[0015] Figure 6 Shows Figure 1 An example of the relationship between the membrane voltage and noise of an imaging element.

[0016] Figure 7 Shows Figure 1 An example of an image quality adjustment process for an imaging element.

[0017] Figure 8 Shows Figure 1 A modified example of the schematic configuration of the imaging element.

[0018] Fig. 9 Shows Figure 1 A modified example of the schematic configuration of the imaging element.

[0019] Fig.10 An example of the relationship between the analog range of the ADC and the amplitude of the pixel signal is shown.

[0020] Fig.11 Shows Fig. 9 An example of an image quality adjustment process for an imaging element.

[0021] Fig.12 Shows Fig. 9 A modified example of the schematic configuration of the imaging element.

[0022] Fig.13 Shows Fig. 9 A modified example of the schematic configuration of the imaging element.

[0023] Fig.14 Shows Figure 1 A modified example of the schematic configuration of the imaging element.

[0024] Fig.15 Shows Fig.14 An example of a circuit configuration of a sensor pixel.

[0025] Fig.16An example of the relationship between the analog range of the ADC and the amplitude of the pixel signal is shown.

[0026] Fig.17 Shows Fig.14 An example of an image quality adjustment process for an imaging element.

[0027] Fig.18 Shows Fig.14 A modified example of the schematic configuration of the imaging element.

[0028] Fig.19 Shows Fig.14 A modified example of the schematic configuration of the imaging element.

[0029] Fig. 20 Shows Figure 2 A modified example of the circuit configuration of a sensor pixel.

[0030] Fig.21 Shows Fig.15 A modified example of the circuit configuration of a sensor pixel.

[0031] Fig. 22 Shows Figure 2 A modified example of the circuit configuration of a sensor pixel.

[0032] Fig.23 Shows Fig.15 A modified example of the circuit configuration of a sensor pixel.

[0033] Fig.24 Shows Figure 3 A modified example of the cross-sectional structure of the imaging element.

[0034] Fig.25 Shows Figure 1 An example of a planar configuration of an imaging element.

[0035] Fig.26 Shows Fig.25 An example of a cross-section of an imaging element along line AA.

[0036] Fig. 27 A schematic configuration example of an imaging device according to a second embodiment of the present disclosure is shown.

[0037] Fig.28 Shows Fig. 27 An example of an imaging process in an imaging device.

[0038] Fig.29 Shows Fig. 27 A modified example of the schematic configuration of the imaging device.

[0039] Fig.30is a block diagram showing an example of a schematic configuration of a vehicle control system.

[0040] Fig.31 It is a diagram for assisting in explaining an example of the installation positions of the vehicle exterior information detection unit and the imaging unit.

[0041] Fig.32 : is a diagram showing an example of a schematic configuration of an endoscopic surgery system.

[0042] Fig.33 is a block diagram showing an example of the functional configuration of a camera head and a camera control unit (CCU). DETAILED DESCRIPTION

[0043] Hereinafter, a detailed description will be given of an embodiment for implementing the present disclosure with reference to the accompanying drawings. It should be noted that the description is given in the following order.

[0044] 1. First Embodiment (Imaging Element) …… Figure 1 to Figure 7

[0045] 2. Modification of the First Embodiment (Imaging Element) …… Figure 8 to Figure 26

[0046] 3. Second Embodiment (Image Forming Device) …… Fig. 27 and Fig.28

[0047] 4. Modification of the Second Embodiment (Imaging Device) …… Fig.29

[0048] 5. Application examples

[0049] Application Example 1 (Mobile Object) …… Fig.30 and Fig.31

[0050] Application Example 2 (Surgical System) …… Fig.32 and Fig.33

[0051] <1. First Implementation Method>

[0052] [constitute]

[0053] A description is given of an imaging element 1 according to a first embodiment of the present disclosure. Figure 1 1 shows a schematic configuration example of an imaging element 1. The imaging element 1 is, for example, an infrared image sensor, and is also sensitive to light having a wavelength of, for example, 800 nm or more. The imaging element 1 includes a pixel array section 10 in which a plurality of sensor pixels 11 having photoelectric conversion elements are arranged two-dimensionally in rows and columns (matrix). Figure 2As shown, for example, the sensor pixel 11 is composed of a pixel circuit 14 that performs photoelectric conversion and a readout circuit 15 that outputs a pixel signal based on the charge output from the pixel circuit 14 .

[0054] For example, the pixel circuit 14 includes a photodiode PD, a transfer transistor TRG, a floating diffusion FD, and a discharge transistor OFG. For example, the transfer transistor TRG and the discharge transistor OFG are both NMOS (metal oxide semiconductor) transistors. The photodiode PD corresponds to a specific example of the "photoelectric conversion unit" of the present disclosure.

[0055] The photodiode PD is a photoelectric conversion unit that absorbs light of a predetermined wavelength (for example, light of a wavelength in the infrared region, that is, light of a wavelength of 900nm to 1700nm) and generates a signal charge. For example, the photodiode PD contains a compound semiconductor such as a III-V semiconductor. Examples of III-V semiconductors used for the photodiode PD include InGaP, InAlP, InGaAs, InAlAs or a compound semiconductor of a chalcopyrite structure. The compound semiconductor of the chalcopyrite structure is a material having a high light absorption coefficient and high sensitivity in a wide wavelength region, and is preferably used as an n-type semiconductor material for photoelectric conversion. In addition to the above-mentioned compound semiconductors, the photodiode PD may also include amorphous silicon (Si), germanium (Ge), a quantum dot photoelectric conversion film, an organic photoelectric conversion film, and the like.

[0056] The cathode of the photodiode PD is connected to the source of the transfer transistor TRG, and the anode of the photodiode PD is connected to a power supply line to which a voltage Vtop is applied. The drain of the transfer transistor TRG is connected to the floating diffusion FD, and the gate of the transfer transistor TRG is connected to the pixel drive line 12 .

[0057] The transfer transistor TRG is connected between the cathode of the photodiode PD and the floating diffusion FD, and transfers the charge held in the photodiode PD to the floating diffusion FD in response to a control signal applied to the gate electrode. The drain of the transfer transistor TRG is electrically connected to the floating diffusion FD, and the gate of the transfer transistor TRG is connected to the pixel drive line 12.

[0058] The floating diffusion FD is a floating diffusion region that temporarily holds the charge transferred from the photodiode PD via the transfer transistor TRG. For example, the readout circuit 15 is connected to the floating diffusion FD, and the vertical signal line 13 is connected thereto via the readout circuit 15. The floating diffusion FD is connected to the input terminal of the readout circuit 15.

[0059] The drain of the discharge transistor OFG is connected to a power supply line to which a voltage Vdr is applied, and the source thereof is connected to a cathode of the photodiode PD. The discharge transistor OFG initializes (resets) the charge of the photodiode PD in response to a control signal applied to a gate electrode.

[0060] For example, the readout circuit 15 includes a reset transistor RST, a selection transistor SEL, and an amplifier transistor AMP. The source of the reset transistor RST (the input terminal of the readout circuit 15) is connected to the floating diffusion FD, and the drain of the reset transistor RST is connected to the power supply line VDD and the drain of the amplifier transistor AMP. The gate of the reset transistor RST is connected to the pixel drive line 12. The source of the amplifier transistor AMP is connected to the drain of the selection transistor SEL, and the gate of the amplifier transistor AMP is connected to the source of the reset transistor RST. The source of the selection transistor SEL (the output terminal of the readout circuit 15) is connected to the vertical signal line 13, and the gate of the selection transistor SEL is connected to the pixel drive line 12.

[0061] The reset transistor RST initializes (resets) the potential of the floating diffusion FD to a predetermined potential. When the reset transistor RST enters the on state, the potential of the floating diffusion FD is reset to the potential of the power line VDD. The selection transistor SEL controls the output timing of the pixel signal from the readout circuit 15. The amplifier transistor AMP generates a signal of a voltage corresponding to the charge level maintained in the floating diffusion FD as a pixel signal. That is, the amplifier transistor AMP generates a signal of a voltage corresponding to the amount of light received in the sensor pixel 11 as a pixel signal. The amplifier transistor AMP constitutes a source follower amplifier and outputs a pixel signal of a voltage corresponding to the charge level generated in the photodiode PD. When the selection transistor SEL enters the on state, the amplifier transistor AMP amplifies the potential of the floating diffusion FD, and outputs a voltage corresponding to the potential to the horizontal selection circuit 40 described later via the vertical signal line 13.

[0062] It should be noted that the selection transistor SEL may be provided between the power supply line VDD and the amplifier transistor AMP. In this case, the drain of the reset transistor RST is connected to the power supply line VDD and the drain of the selection transistor SEL. The source of the selection transistor SEL is connected to the drain of the amplifier transistor AMP, and the gate of the selection transistor SEL is connected to the pixel drive line 12. The source of the amplifier transistor AMP (the output terminal of the readout circuit 15) is connected to the vertical signal line 13, and the gate of the amplifier transistor AMP is connected to the source of the reset transistor RST.

[0063] For example, Figure 3As shown, the imaging element 1 includes two substrates (a light receiving substrate 100 and a driving substrate 200). The imaging element 1 has a three-dimensional structure formed by bonding the two substrates (the light receiving substrate 100 and the driving substrate 200) together.

[0064] The light receiving substrate 100 is a substrate including a plurality of photodiodes PD formed in a matrix on a silicon (Si) substrate. The upper surface of the light receiving substrate 100 (the front surface on the opposite side of the drive substrate 200) is a light receiving surface 100A. The drive substrate 200 is a substrate including a pixel signal generating circuit area 200A and a peripheral circuit area 200B formed on a Si substrate. A plurality of pixel signal generating circuits 45 are formed in a matrix in the pixel signal generating circuit area 200A. Each pixel signal generating circuit 45 is a circuit that does not include the photodiode PD in the sensor pixel 11. A logic circuit for processing pixel signals is formed in the peripheral circuit area 200B; for example, a vertical drive circuit 20, a horizontal drive circuit 30, a horizontal selection circuit 40, a system control circuit 50, a membrane voltage control unit 60, and a voltage generating circuit 70 are formed. That is, the imaging element 1 includes a pixel array unit 10, a vertical drive circuit 20, a horizontal drive circuit 30, a horizontal selection circuit 40, a system control circuit 50, a membrane voltage control unit 60, and a voltage generating circuit 70. The logic circuit outputs the pixel signal (digital value) of each sensor pixel 11 to the outside.

[0065] The system control circuit 50 generates clock signals, control signals, etc. which serve as operating references for the vertical drive circuit 20, the horizontal drive circuit 30, the horizontal selection circuit 40, the membrane voltage control unit 60, etc. based on the main clock, and provides clock signals, control signals, etc. to the vertical drive circuit 20, the horizontal selection circuit 40, the membrane voltage control unit 60.

[0066] For example, the vertical drive circuit 20 is composed of a shift register or the like, and controls row scanning of a plurality of sensor pixels 11 via a plurality of pixel drive lines 12. For example, the horizontal selection circuit 40 is a circuit provided with an ADC 40a and a switch element 40b for each pixel column (or vertical signal line 13) of the pixel array section 10. The ADC 40a performs AD (analog-to-digital) conversion of a pixel signal. The ADC 40a is capable of making the analog range R variable, and sets the analog range R based on a range setting value input from the outside. It should be noted that in the present embodiment, the analog range R is set to Ra.

[0067] The vertical signal line 13 is connected to the input terminal of the ADC 40a, and the switch element 40b is connected to the output terminal of the ADC 40a. For example, the horizontal drive circuit 30 is composed of a shift register or the like, and sequentially drives the switch elements 40b of the horizontal selection circuit 40. The sequential driving of the switch elements 40b by the horizontal drive circuit 30 causes the pixel signals transmitted through the vertical signal lines 13 to be sequentially output to the horizontal signal line 40c and input to the DSP circuit or the like.

[0068] The membrane voltage control section 60 controls the membrane voltage Vf to be applied to each photodiode PD based on the pixel signal obtained from the sensor pixel 11. The membrane voltage control section 60 outputs a control signal for controlling the membrane voltage Vf to the voltage generation circuit 70. Based on the control signal input from the membrane voltage control section 60, the voltage generation circuit 70 generates an analog voltage (voltages Vtop and Vdr), and applies the generated voltage to each photodiode PD via a power supply line. That is, the membrane voltage control section 60 and the voltage generation circuit 70 apply the membrane voltage Vf based on the pixel signal obtained from the sensor pixel 11 to each photodiode PD, thereby controlling the image quality of the image data obtained from the pixel signal.

[0069] Figure 4 1 shows a cross-sectional configuration example of the imaging element 1. In the imaging element 1, the light receiving substrate 100 includes an n-type semiconductor film 21 as a photoelectric conversion section (photodiode PD). The n-type semiconductor film 21 is formed on the entire surface of the pixel array section 10, and is composed of, for example, the above-mentioned material as the material for the photodiode PD. It should be noted that the following description of other configurations is given, in which it is assumed that the n-type semiconductor film 21 is composed of InGaAs.

[0070] For each sensor pixel 11, the light receiving substrate 100 also includes a p-type semiconductor layer 22 in contact with the surface of the n-type semiconductor film 21 on the driving substrate 200 side. Each p-type semiconductor layer 22 is formed of a high-concentration p-type semiconductor, and is formed of, for example, p-type InGaAs. The p-type semiconductor layer 22 has a function as an electrode (second electrode) of the photodiode PD. A predetermined voltage Vdr is applied to the p-type semiconductor layer 22 via the discharge transistor OFG in the on state, or a voltage Vdd of the power line VDD is applied thereto via the transfer transistor TRG and the reset transistor RST in the on state. The light receiving substrate 100 also includes an n-type semiconductor layer 23 that separates the p-type semiconductor layers 22 from each other. The n-type semiconductor layer 23 is formed in the same layer as the p-type semiconductor layers 22, and is formed of, for example, n-type InP.

[0071] The light receiving substrate 100 also includes an n-type semiconductor layer 24 in contact with the surface of the light receiving surface 100A side of the n-type semiconductor film 21. The n-type semiconductor layer 24 is formed of an n-type semiconductor having a higher concentration than the n-type semiconductor film 21, and is formed, for example, of n-type InGaAs, n-type InP or n-type InAlAs. The n-type semiconductor layer 24 serves as a barrier layer for preventing the backflow of charges generated in the n-type semiconductor film 21. The light receiving substrate 100 also includes an anti-reflection film 25 in contact with the surface of the light receiving surface 100A side of the n-type semiconductor layer 24. For example, the anti-reflection film 25 is formed of silicon nitride (SiN), hafnium oxide (HfO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), tantalum oxide (Ta2O5), titanium oxide (TiO2), etc. The n-type semiconductor layer 24 is also used as an upper electrode (first electrode) of the electrodes sandwiching the n-type semiconductor film 21 from top to bottom. A predetermined voltage Vtop is applied to the upper electrode.

[0072] The light receiving substrate 100 further includes a color filter 26 and an on-chip lens 27 on the upper portion of the anti-reflection film 25. The color filter 26 is composed of a plurality of filters 26R that selectively transmit red light, a plurality of filters 26G that selectively transmit green light, and a plurality of filters 26B that selectively transmit blue light. For example, the plurality of filters 26R, 26G, and 26B are provided one by one for each sensor pixel 11, and are arranged in a plane parallel to the light receiving surface 100A in a Bayer arrangement, for example. It should be noted that in Figure 4 , the sensor pixel 11 provided with the color filter 26R is indicated as 11R; the sensor pixel 11 provided with the color filter 26G is indicated as 11G; and the sensor pixel 11 provided with the color filter 26B is indicated as 11B. It should be noted that the color filter 26 may be omitted as necessary.

[0073] The light receiving substrate 100 further includes a passivation layer 28 and an insulating layer 29 on the lower side of the p-type semiconductor layer 22 and the n-type semiconductor layer 23. The light receiving substrate 100 further includes a connection electrode 31 that penetrates the passivation layer 28 and contacts the p-type semiconductor layer 22, and a bump electrode 32 that penetrates the insulating layer 29 and contacts the connection electrode 31. A set of the connection electrode 31 and the bump electrode 32 is provided one by one for each sensor pixel 11. The bump electrode 32 is bonded to a connection layer 43 (described later) of the drive substrate 200 and is electrically connected to the connection layer 43. For example, when the light receiving substrate 100 and the drive substrate 200 are attached to each other, the bump electrode 32 is bonded to the connection layer 43 of the drive substrate 200.

[0074] The drive substrate 200 includes a support substrate 41 and an interlayer insulating layer 42. For example, the support substrate 41 is composed of a silicon (Si) substrate. The interlayer insulating layer 42 is provided between the support substrate 41 and the insulating layer 29 (light receiving substrate 100). For example, the interlayer insulating layer 42 includes a plurality of connection layers 43, a plurality of readout electrodes 44, a plurality of pixel signal generating circuits 45, and a plurality of wirings 46 in sequence from a position close to the light receiving substrate 100. Multiple groups of connection layers 43, readout electrodes 44, pixel signal generating circuits 45, and wirings 46 are provided one by one for each sensor pixel 11. For example, a plurality of interlayer insulating layers 42 within the interlayer insulating layer 42 are provided inside a ROIC (readout IC) for reading out charges from each photodiode PD. The drive substrate 200 is provided with the above-mentioned logic circuit at a position corresponding to the peripheral circuit area 200B in the interlayer insulating layer 42.

[0075] Figure 5 (A) shows an example of the relationship between the film voltage Vf to be applied to the photodiode PD and the charge Qs that can be held in the photodiode PD. Figure 5 (B) shows an example of the relationship between the analog range (dynamic range) of the ADC 40 a and the amplitude Vd of the pixel signal. Figure 5 (B) illustrates a case where the analog range of the ADC 40a is set to Ra.

[0076] from Figure 5 As can be seen from (A), as the voltage to be applied to the photodiode PD (n-type semiconductor film 21) (film voltage Vf = Vtop-Vdr) increases, the amount of charge Qs that can be held in the photodiode PD (n-type semiconductor film 21) also increases. As the amount of charge Qs held in the photodiode PD (n-type semiconductor film 21) increases, the amplitude Vd of the pixel signal also increases. However, as Figure 5 As shown in (B), it is important that the average value Vdavg (described later) of the amplitude Vd of the pixel signal does not exceed the voltage Vda corresponding to the analog range Ra of the ADC 40a. When the average value Vdavg of the amplitude Vd of the pixel signal exceeds the voltage Vda corresponding to the analog range Ra of the ADC 40a, the ADC 40a is saturated and the output of the ADC 40a becomes a constant value.

[0077] Figure 6 An example of the relationship between the film voltage Vf to be applied to the photodiode PD and the noise (dark current) generated in the photodiode PD is shown. Figure 6It can be seen that as the voltage to be applied to the photodiode PD (n-type semiconductor film 21) (film voltage Vf = Vtop-Vdr) increases, the level of noise (dark current) generated in the photodiode PD increases exponentially. Therefore, at high brightness, light shot noise dominates, so the film voltage Vf is set to be higher, and at low brightness, noise (dark current) dominates, so the film voltage Vf is set to be lower, thereby being able to suppress degradation of image quality.

[0078] [Image quality adjustment]

[0079] Next, refer to Figure 7 A description is given of an image quality adjustment process of the imaging element 1 . Figure 7 An example of an image quality adjustment process of the imaging element 1 is shown. When an imaging instruction is received, the system control circuit 50 outputs a membrane voltage setting instruction to the membrane voltage control section 60. When the membrane voltage setting instruction is received, the membrane voltage control section 60 first sets the membrane voltage Vf to Vfa (step S101). Specifically, the membrane voltage control section 60 sets Vtop (first voltage) and Vdr (second voltage) so that the potential difference (Vtop-Vdr) between Vtop and Vdr becomes Vfa. For example, the membrane voltage control section 60 sets Vtop to +2V and sets Vdr to +1V. The membrane voltage control section 60 outputs the set values ​​of Vtop and Vdr to the voltage generating circuit 70. Based on the set values ​​input from the membrane voltage control section 60, the voltage generating circuit 70 applies a voltage of Vtop=+2V to the power line connected to the anode of the photodiode PD, and applies a voltage of Vdr=+1V to the power line connected to the drain of the discharge transistor OFG.

[0080] Next, the film voltage control unit 60 determines whether the average value Vdavg of the plurality of pixel signals obtained from the plurality of sensor pixels 11 in the target area of the pixel array unit 10 exceeds a predetermined threshold value Vth1 (first threshold value) (step S102). The threshold value Vth1 is a threshold value for determining whether the optical shot noise dominates when the film voltage Vf is set to Vfa. As a result, when the average value Vdavg exceeds the predetermined threshold value Vth1, the film voltage control unit 60 sets the film voltage Vf to Vfb (Vfb > Vfa) (step S103). That is, the film voltage control unit 60 makes the film voltage Vf relatively larger than Vfa. Specifically, the film voltage control unit 60 sets Vtop and Vdr based on the average value Vdavg so that Vtop - Vdr becomes Vfb. For example, the film voltage control unit 60 sets Vtop to +3V and Vdr to +1V. The film voltage control unit 60 outputs the set values of Vtop and Vdr to the voltage generation circuit 70. Based on the set values input from the film voltage control unit 60, the voltage generation circuit 70 applies a voltage of Vtop = +3V to the power supply line connected to the anode of the photodiode PD, and applies a voltage of Vdr = +1V to the power supply line connected to the drain of the discharge transistor OFG.

[0081] When the average value Vdavg is equal to or less than the predetermined threshold value Vthl and when the film voltage Vf is set to Vfb (Vfb > Vfa), the film voltage control unit 60 determines whether the average value Vdavg falls below a predetermined threshold value Vth2 (second threshold value) (Vth2 < Vth1) (step S104). The threshold value Vth2 is a threshold value for determining whether the pixel signal is buried in noise. As a result, when the average value Vdavg falls below the predetermined threshold value Vth2, the film voltage control unit 60 sets the film voltage Vf to Vfc (Vfc < Vfa) (step S105). That is, the film voltage control unit 60 makes the film voltage Vf relatively smaller than Vfa. Specifically, the film voltage control unit 60 sets Vtop and Vdr based on the average value Vdavg so that Vtop - Vdr becomes Vfc. On the other hand, when the average value Vdavg is equal to or greater than the predetermined threshold value Vth2, the film voltage control unit 60 retains the set value of the voltage as it is. When receiving an instruction to complete imaging, the system control circuit 50 completes imaging and also completes the image quality adjustment of the imaging element 1 (step S106). When not receiving an instruction to complete imaging, the system control circuit 50 instructs the film voltage control unit 60 to execute again from step S102. In this way, the image quality adjustment of the imaging element 1 is performed.

[0082] [Effect]

[0083] In the present embodiment, applying a membrane voltage Vf based on the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) to each photodiode PD (n-type semiconductor film 21) allows control of the image quality of the image data obtained from the pixel signal. Specifically, when the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) exceeds the threshold value Vth1, the membrane voltage Vf is set to be relatively large, and when the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) falls below the threshold value Vth2, the membrane voltage Vf is set to be relatively small. In this way, in the present embodiment, at high brightness, the membrane voltage Vf is set to be relatively large to reduce the influence of optical shot noise, and at low brightness, the membrane voltage Vf is set to be relatively small to increase the S / N ratio. This can suppress the degradation of image quality.

[0084] In addition, in this embodiment, voltage Vtop and voltage Vdr are generated based on the pixel signal so that the potential difference (Vtop-Vdr) between voltage Vtop and voltage Vdr becomes film voltage Vf. The film voltage Vf thus generated is applied to each photodiode PD (n-type semiconductor film 21), thereby suppressing the degradation of image quality.

[0085] In addition, in the present embodiment, each pixel circuit 14 includes a photodiode PD (n-type semiconductor film 21), a transfer transistor TRG, and a discharge transistor OFG. When the discharge transistor is turned on, Vdr is applied to the p-type semiconductor layer 22. This allows the film voltage Vf to be applied to each photodiode PD (n-type semiconductor film 21) based on the pixel signal. Therefore, degradation of image quality can be suppressed.

[0086] <2. Modification of the First Implementation Example>

[0087] [[Variant A]]

[0088] In the above-described embodiment, the membrane voltage control section 60 and the voltage generating circuit 70 are provided inside the imaging element 1, but for example, Figure 8 As shown, it can also be set inside the image quality control circuit 2 separated from the imaging element 1. In this case, for example, Figure 8 As shown, the membrane voltage control section 60 can set the membrane voltage Vf based on the output of the imaging element 1. Also in this case, effects similar to those of the above-described embodiment are achieved.

[0089] [[Variant B]]

[0090] In the above embodiments, for example, Fig. 9As shown, the imaging element 1 may further include an analog range control section 80. The analog range control section 80 controls the analog range R of the ADC 40a based on the determination result (i.e., the output (average value Vdavg of the amplitude Vd of the pixel signal)) input from the membrane voltage control section 60. Specifically, the analog range control section 80 outputs a range setting value based on the determination result (i.e., the output (average value Vdavg of the amplitude Vd of the pixel signal)) input from the membrane voltage control section 60 to the ADC 40a, thereby controlling the image quality of the image data obtained from the pixel signal.

[0091] Fig.10 is an example of the relationship between the analog range R (dynamic range) of the ADC 40 a and the amplitude Vd of the pixel signal. Fig.10 The case where the analog range R of the ADC 40 a is set to Ra or Rb is illustrated.

[0092] like Fig.10 As shown, when the average value Vdavg of the amplitude Vd of the pixel signal exceeds the voltage Vda corresponding to the analog range Ra of the ADC 40a, the ADC 40a is saturated. However, by expanding the analog range R of the ADC 40a from Ra to Rb, the average value Vdavg of the amplitude Vd of the pixel signal falls below the voltage Vdb corresponding to the analog range Rb of the ADC 40a, and the saturation of the ADC 40a is eliminated. Therefore, at high brightness, the dynamic range R of the ADC 40a is set higher to prevent overexposure, while at low brightness, noise (dark current) dominates, and therefore, setting the dynamic range R of the ADC 40a to be lower can suppress the degradation of image quality.

[0093] [Image quality adjustment]

[0094] Next, refer to Fig.11 A description is given of image quality adjustment of the imaging element 1 according to the present modification. Fig.11 FIG. 2 shows an example of an image quality adjustment process of the imaging element 1 according to the present modification. It should be noted that in the present modification, the imaging element 1 performs Figure 7 The image quality adjustment process shown in the figure is performed Fig.11 The image quality adjustment process is shown.

[0095] The analog range control unit 80 first sets the analog range R of the ADC 40a to Ra (step S201). Specifically, the analog range control unit 80 outputs a control signal for setting the analog range R to Ra to the ADC 40a. When the control signal for setting the analog range R to Ra is input from the analog range control unit 80, the ADC 40a sets the analog range R to Ra.

[0096] Next, when the determination result input from the membrane voltage control unit 60 is "Vdavg > Vth3", the analog range control unit 80 sets the analog range R to Rb (Rb > Ra) (Steps S202 and S203). That is, the analog range control unit 80 makes the analog range R relatively larger than Ra. The threshold Vth3 (first threshold) is a threshold for determining whether an image has overexposure when the membrane voltage Vf is set to Vfa. At this time, the analog range control unit 80 outputs a control signal for setting the analog range R to Rb to the ADC 40a. When the control signal for setting the analog range R to Rb is input from the analog range control unit 80, the ADC 40a sets the analog range R to Rb.

[0097] When the determination result input from the membrane voltage control unit 60 is "Vdavg ≤ Vth3" or when the analog range R is set to Rb, the analog range control unit 80 waits for the determination result of the magnitude relationship between the average value Vdavg and the threshold Vth2 to be input from the membrane voltage control unit 60. At this time, when the determination result input from the membrane voltage control unit 60 is "Vdavg < Vth2" (Vth2 < Vth3), the analog range control unit 80 sets the analog range R to Ra (Steps S204 and 201). That is, the analog range control unit 80 makes the analog range R relatively smaller than Rb. Specifically, the analog range control unit 80 outputs a control signal for setting the analog range R to Ra to the ADC 40a. When the control signal for setting the analog range R to Ra is input from the analog range control unit 80, the ADC 40a sets the analog range R to Ra.

[0098] When the determination result input from the membrane voltage control unit 60 is "Vdavg ≥ Vth2", the analog range control unit 80 executes Step S202 when the imaging completion instruction has not been input (Steps S204 and 205). When the imaging completion instruction is input, the analog range control unit 80 completes the setting of the analog range R (Step S205). In this way, the image quality adjustment of the imaging element 1 is performed.

[0099] [Effect]

[0100] In the present modification, applying a membrane voltage Vf based on the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) to each photodiode PD (n-type semiconductor film 21) allows control of the image quality of the image data obtained from the pixel signal. Specifically, when the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) exceeds the threshold value Vth1, the membrane voltage Vf is set to be relatively large, and when the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) falls below the threshold value Vth2, the membrane voltage Vf is set to be relatively small. In this way, in the present modification, at high brightness, the membrane voltage Vf is set to be relatively large to reduce the influence of optical shot noise, and at low brightness, the membrane voltage Vf is set to be relatively small to increase the S / N ratio. This can suppress the degradation of image quality.

[0101] In this modification, outputting the range setting value based on the pixel signal to the ADC 40a also allows control of the image quality of the image data obtained from the pixel signal. Specifically, when the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) exceeds the threshold value Vth3, the range setting value is set to be relatively large, and when the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) falls below the threshold value Vth2, the range setting value is set to be relatively small. In this way, in this modification, at high brightness, the range setting value is set to be relatively large to suppress overexposure of the image, and at low brightness, the range setting value is set to be relatively small to increase the S / N ratio. This can suppress the degradation of image quality.

[0102] [[Variant C]]

[0103] In the above-mentioned modification B, the membrane voltage control section 60, the voltage generating circuit 70 and the analog range control section 80 are provided inside the imaging element 1, but for example, Fig.12 As shown, it can also be set inside the image quality control circuit 2 separated from the imaging element 1. In this case, for example, Fig.12 As shown, the membrane voltage control section 60 can set the membrane voltage Vf based on the output of the imaging element 1. Also in this case, effects similar to those of the above-described embodiment are achieved.

[0104] [[Variant D]]

[0105] In the above-mentioned modification B, the membrane voltage control section 60, the voltage generation circuit 70, and the analog range control section 80 are provided inside the imaging element 1. However, for example, Fig.13 As shown, the membrane voltage control section 60 and the voltage generation circuit 70 may be provided inside the image quality control circuit 2 separated from the imaging element 1 , and the analog range control section 80 may be provided inside the imaging element 1 .

[0106] In this case, for example, Fig.13 As shown in FIG. 1 , the membrane voltage control section 60 can set the membrane voltage Vf based on the output of the imaging element 1. In addition, for example, Fig.13 As shown, the analog range control section 80 can set the analog range R of the ADC 40 a based on the value of the output voltage (Vtop and Vdr) of the voltage generating circuit 70 .

[0107] In the present modification, the film voltage Vf to be applied to each photodiode PD (n-type semiconductor film 21) is set based on the output of the imaging element 1, and the analog range R of the ADC 40a is set based on the value of the voltage (Vtop and Vdr) applied to each photodiode PD (n-type semiconductor film 21). This can suppress the degradation of image quality.

[0108] [[Variant E]]

[0109] In the above embodiments, for example, Fig.14 As shown, the imaging element 1 may further include a conversion efficiency control section 90. The conversion efficiency control section 90 controls the conversion efficiency η of the pixel circuit 14 based on the determination result (i.e., the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal)) input from the membrane voltage control section 60. Specifically, the conversion efficiency control section 90 outputs a control signal based on the determination result (i.e., the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal)) input from the membrane voltage control section 60 to the switching element SW described later, thereby controlling the image quality of the image data obtained from the pixel signal.

[0110] Fig.15 An example of the circuit configuration of the sensor pixel 11 according to the present modification is shown. In the sensor pixel 11 according to the present modification, the pixel circuit 14 includes a switching element SW connected to the floating diffusion FD and an auxiliary capacitor Ce connected in parallel with the capacitor (FD capacitor Cfd) of the floating diffusion FD via the switching element SW. The conversion efficiency control section 90 controls the ON / OFF of the switching element SW, thereby controlling the conversion efficiency η of the pixel circuit 14.

[0111] Fig.16 An example of the relationship between the analog range R of the ADC 40 a and the amplitude Vd of the pixel signal is shown. Fig.16 The case where the analog range R of the ADC 40 a is set to Rb is illustrated.

[0112] When the switching element SW is turned on by the control of the conversion efficiency control unit 90, the voltage generated by the charges accumulated in the FD capacitor Cfd and the auxiliary capacitor Ce connected in parallel to each other is input to the readout circuit 15. At this time, the conversion efficiency η of the pixel circuit 14 is limited to η1. When the switching element SW is turned off by the control of the conversion efficiency control unit 90, the auxiliary capacitor Ce is separated from the floating diffusion unit FD, and therefore, the voltage generated by the charges accumulated in the FD capacitor Cfd is input to the readout circuit 15. At this time, the conversion efficiency η2 of the pixel circuit 14 becomes η1 / α. Here, α is (Cfd+Ce) / Cfd). That is, turning off the switching element SW reduces the conversion efficiency η by 1 / α. For example, in the case where the auxiliary capacitor Ce has a capacity twice that of the FD capacitor Cfd, the conversion efficiency η2 is 1 / 3 times the conversion efficiency η1. For example, as Fig.16 As shown, when the conversion efficiency η decreases, the amplitude Vd of the pixel signal decreases by the amount of decrease in the conversion efficiency η. Therefore, for example, in the case where the average value Vdavg1 when the switch element SW is turned on is greater than the voltage value Vdb corresponding to the upper limit (Rb) of the analog range R of the ADC 40a to saturate the ADC 40a, turning off the switch element SW can make the average value Vdavg2 when the switch element SW is turned off become Vdavg1 / α less than the voltage value Vdb. Therefore, at high brightness, the conversion efficiency η is set to be lower to prevent overexposure, and at low brightness, noise (dark current) dominates, so setting the conversion efficiency η to be higher can suppress the degradation of image quality.

[0113] [Image quality adjustment]

[0114] Next, refer to Fig.17 A description is given of an image quality adjustment process of the imaging element 1 . Fig.17 FIG. 1 shows an example of an image quality adjustment process of the imaging element 1. It should be noted that in this modification, the imaging element 1 performs Figure 7 The image quality adjustment process shown in the figure is performed Fig.17 The image quality adjustment process is shown.

[0115] The conversion efficiency control section 90 first sets the conversion efficiency η of the pixel circuit 14 to η1 (step S301). Specifically, the conversion efficiency control section 90 outputs a control signal for turning on the switch element SW to the switch element SW inside the pixel circuit 14. When the control signal for turning on the switch element SW is input from the conversion efficiency control section 90, the switch element SW is turned on. This connects the FD capacitor Cfd and the auxiliary capacitor Ce in parallel with each other.

[0116] Next, when the determination result input from the film voltage control unit 60 is "Vdavg > Vth3", the conversion efficiency control unit 90 sets the conversion efficiency η to η2 (η2 < η1) (Steps S302 and S303). At this time, the conversion efficiency control unit 90 outputs a control signal for turning off the switching element SW to the switching element SW. When the control signal for turning off the switching element SW is input from the conversion efficiency control unit 90, the switching element SW turns off. That is, when the average value Vdavg exceeds Vth3, the conversion efficiency control unit 90 turns off the switching element SW. This separates the auxiliary capacitor Ce and the floating diffusion section FD.

[0117] When the determination result input from the film voltage control unit 60 is "Vdavg ≤ Vth3" or when the switching element SW is set to off, the conversion efficiency control unit 90 waits for the determination result of the magnitude relationship between the average value Vdavg and the threshold value Vth2 (Vth2 < Vth3) to be input from the film voltage control unit 60. At this time, when the determination result input from the film voltage control unit 60 is "Vdavg < Vth2", the conversion efficiency control unit 90 sets the conversion efficiency η to η1 (Steps S304 and S301). Specifically, the conversion efficiency control unit 90 outputs a control signal for turning on the switching element SW to the switching element SW. When the control signal for turning on the switching element SW is input from the conversion efficiency control unit 90, the switching element SW turns on. That is, when the average value Vdavg falls below Vth2 which is less than Vth3, the conversion efficiency control unit 90 turns on the switching element SW. This connects the FD capacitor Cfd and the auxiliary capacitor Ce in parallel with each other.

[0118] When the determination result input from the film voltage control unit 60 is "Vdavg ≥ Vth2" and when the instruction to complete imaging is not input, the conversion efficiency control unit 90 executes Step S302 (Steps S304 and S302). When the instruction to complete imaging is input, the conversion efficiency control unit 90 completes the setting of the conversion efficiency η (Step S305). In this way, the image quality adjustment of the imaging element 1 is performed.

[0119] [Effect]

[0120] In the present modification, applying a membrane voltage Vf based on the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) to each photodiode PD (n-type semiconductor film 21) allows control of the image quality of the image data obtained from the pixel signal. Specifically, when the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) exceeds the threshold value Vth1, the membrane voltage Vf is set to be relatively large, and when the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) falls below the threshold value Vth2, the membrane voltage Vf is set to be relatively small. In this way, in the present modification, at high brightness, the membrane voltage Vf is set to be relatively large to reduce the influence of optical shot noise, and at low brightness, the membrane voltage Vf is set to be relatively small to increase the S / N ratio. This can suppress the degradation of image quality.

[0121] In this modification, outputting a control signal based on a pixel signal to the switching element SW also allows control of the image quality of the image data obtained from the pixel signal. Specifically, when the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) exceeds the threshold value Vth3, the switching element SW is disconnected, and when the output of the imaging element 1 (the average value Vdavg of the amplitude Vd of the pixel signal) falls below the threshold value Vth2, the switching element SW is turned on. In this way, in this modification, at high brightness, the switching element SW is disconnected to suppress overexposure of the image, and at low brightness, the switching element SW is turned on to increase the S / N ratio. This can suppress the degradation of image quality.

[0122] [[Variant F]]

[0123] In the above-mentioned modification E, the film voltage control section 60, the voltage generation circuit 70 and the conversion efficiency control section 90 are provided inside the imaging element 1. However, for example, Fig.18 As shown, the film voltage control section 60, the voltage generation circuit 70 and the conversion efficiency control section 90 may be provided inside the image quality control circuit 2 which is separated from the imaging element 1. In this case, for example, Fig.18 As shown, the membrane voltage control section 60 can set the membrane voltage Vf based on the output of the imaging element 1. Also in this case, effects similar to those of the above-described embodiment are achieved.

[0124] [[Variant G]]

[0125] In the above-mentioned modification E, the film voltage control section 60, the voltage generating circuit 70 and the conversion efficiency control section 90 are provided inside the imaging element 1. However, the film voltage control section 60 and the voltage generating circuit 70 may be provided inside the image quality control circuit 2 separated from the imaging element 1, and for example, Fig.19As shown, the conversion efficiency control section 90 may be provided inside the imaging element 1 .

[0126] In this case, for example, Fig.19 As shown in FIG. 1 , the membrane voltage control section 60 can set the membrane voltage Vf based on the output of the imaging element 1. In addition, for example, Fig.19 As shown, the conversion efficiency control section 90 can set the conversion efficiency η of the pixel circuit 14 based on the value of the output voltage (Vtop and Vdr) of the voltage generation circuit 70.

[0127] In the present modification, the film voltage Vf to be applied to the photodiode PD (n-type semiconductor film 21) is set based on the output of the imaging element 1, and the conversion efficiency η of the pixel circuit 14 is set based on the value of the voltage (Vtop and Vdr) to be applied to the photodiode PD (n-type semiconductor film 21). This can suppress the degradation of image quality.

[0128] [[Variant H]]

[0129] In the above-mentioned embodiments and their variations, for example, Fig. 20 and Fig.21 As shown, the drain transistor OFG in the pixel circuit 14 can be omitted. At this time, the membrane voltage control section 60 can generate a voltage Vtop based on the pixel signal to allow the potential difference (Vtop-Vdr) between the voltage Vtop to be applied to the n-type semiconductor layer 24 and the voltage Vdr of the p-type semiconductor layer 22 applied by the reset transistor RST when the transfer transistor TRG is turned on to become the membrane voltage Vf.

[0130] In addition, in the above-mentioned embodiment and its modification, for example, Fig. 22 and Fig.23 As shown, the discharge transistor OFG and the transfer transistor TRG in the pixel circuit 14 can be omitted. At this time, the membrane voltage control section 60 can generate a voltage Vtop based on the pixel signal to allow the potential difference (Vtop-Vdr) between the voltage Vtop to be applied to the n-type semiconductor layer 24 and the voltage Vdr of the p-type semiconductor layer 22 applied by the reset transistor RST to become the membrane voltage Vf.

[0131] Also in this case, the present modification achieves effects similar to those of the imaging element 1 according to any of the above-described embodiments and the modification examples thereof.

[0132] [[Variation Example I]]

[0133] In the above embodiment and its modified examples A to H, the light receiving substrate 100 and the driving substrate 200 are bump-bonded. However, in the above embodiment and its modified examples A to H, the light receiving substrate 100 and the driving substrate 200 may be Cu-Cu bonded. Fig.24 A modification example of the cross-sectional structure of the imaging element 1 according to this modification example is shown.

[0134] The light receiving substrate 100 includes an insulating film 33 , a buried layer 34 , interlayer insulating films 35 and 36 , a plurality of electrodes 37 , and a plurality of contact electrodes 38 instead of the passivation layer 28 , the insulating layer 29 , the plurality of connection electrodes 31 , and the plurality of bump electrodes 32 .

[0135] The insulating film 33 covers the n-type semiconductor layer 23 and a portion of each p-type semiconductor layer 22, and has an opening at a position facing each p-type semiconductor layer 22. For example, the insulating film 33 includes a material such as silicon oxide (SiO x ) or an oxide such as aluminum oxide (Al2O3). For example, the insulating film 33 may be composed of a multilayer structure including a plurality of films. For example, the insulating film 33 may be composed of a silicon (Si)-based insulating material such as silicon oxynitride (SiON), carbon-containing silicon oxide (SiOC), silicon nitride (SiN), and silicon carbide (SiC). For example, the insulating film 33 has a thickness of several tens of nm to several hundreds of nm.

[0136] A plurality of electrodes 37 are disposed one by one in each opening of the insulating film 33, and are disposed one by one for each p-type semiconductor layer 22. Each electrode 37 is in contact with the corresponding p-type semiconductor layer 22. For example, each electrode 37 is composed of a single substance of titanium (Ti), tungsten (W), titanium nitride (TiN), platinum (Pt), gold (Au), germanium (Ge), palladium (Pd), zinc (Zn), nickel (Ni) and aluminum (Al), or an alloy containing at least one of them. Each electrode 37 may be a single-layer film of such a constituent material, or may be a laminated film in which two or more of them are combined. For example, each electrode 37 is composed of a laminated film of titanium and tungsten. For example, each electrode 37 has a thickness of several tens of nm to several hundreds of nm.

[0137] The buried layer 34 is formed by burying the electrode 37. In the buried layer 34, the surface on the drive substrate 200 side is flat. For example, the buried layer 34 is made of a material such as silicon oxide (SiO x ), silicon nitride (SiN), silicon oxynitride (SiON), carbon-containing silicon oxide (SiOC) and silicon carbide (SiC) and other inorganic insulating materials.

[0138] The interlayer insulating films 35 and 36 are stacked in this order on the flat surface of the buried layer 34 on the drive substrate 200 side. For example, the interlayer insulating films 35 and 36 are each composed of an inorganic insulating material. Examples of inorganic insulating materials include silicon nitride (SiN), aluminum oxide (Al2O3), silicon oxide (SiO2), and hafnium oxide (HfO2). The interlayer insulating films 35 and 36 can be composed of the same inorganic insulating material.

[0139] A plurality of contact electrodes 38 are provided one by one for each electrode 37. Each electrode 38 is in contact with the corresponding electrode 37. The surface of each contact electrode 38 on the drive substrate 200 side is exposed from the interlayer insulating film 36. The surface of each contact electrode 38 on the drive substrate 200 side and the surface of the interlayer insulating film 36 on the drive substrate 200 side are arranged in the same plane.

[0140] The drive substrate 200 includes a plurality of contact electrodes 47 instead of the plurality of connection layers 43. The drive substrate 200 also includes interlayer insulating films 48 and 49. The plurality of contact electrodes 47 are provided one by one for each readout electrode 44. Each contact electrode 47 is in contact with the corresponding readout electrode 44.

[0141] The interlayer insulating films 48 and 49 are stacked in this order on the surface of the light receiving substrate 100 side of the interlayer insulating layer 42. For example, the interlayer insulating films 48 and 49 are each composed of an inorganic insulating film material. Examples of the inorganic insulating material include silicon nitride (SiN), aluminum oxide (Al2O3), silicon oxide (SiO2), and hafnium oxide (HfO2).

[0142] The surface of each contact electrode 47 on the light receiving substrate 100 side is exposed from the interlayer insulating film 49. The surface of each contact electrode 47 on the light receiving substrate 100 side and the surface of the interlayer insulating film 49 on the light receiving substrate 100 side are arranged in the same plane. For example, the contact electrodes 38 and 47 are both made of copper (Cu). The contact electrode 38 and the contact electrode 47 are bonded to each other.

[0143] Fig.25 An example of a planar configuration of the imaging element 1 according to the present modification is shown. Fig.26 Shows Fig.25 An example of an imaging element 1 constructed along a cross section of line AA. The imaging element 1 includes an element region R1 located in a central portion and a peripheral region R2 provided outside the element region R1 and surrounding the element region R1. The element region R1 corresponds to a position in the imaging element 1 where an n-type semiconductor film 21 (photodiode PD) is provided. The imaging element 1 includes a conductive film 51 provided from the element region R1 to the peripheral region R2. The conductive film 51 has an opening in a region facing the central portion of the element region R1. The region exposed from the conductive film 51 in the element region R1 (the region facing the opening of the conductive film 51) is a light receiving region. The region covered by the conductive film 51 in the element region R1 is an optical black (OPB: Optical Black) region. The OPB region is provided to surround the light receiving region. The OPB region is used to obtain a pixel signal at a black level.

[0144] In the light receiving substrate 100, the insulating film 33 covers the n-type semiconductor layer 23 and a part of each p-type semiconductor layer 22, and covers the side of the n-type semiconductor film 21 (photodiode PD). In the light receiving substrate 100, the buried layer 34 covers the side of the n-type semiconductor film 21 with the insulating film 33 interposed therebetween, and is provided from the element region R1 to the peripheral region R2. The peripheral region R2 is provided with holes H1 and H2 that penetrate the light receiving substrate 100 to reach the drive substrate 200.

[0145] The hole H1 is provided at a position closer to the element region R1 than the hole H2, and the side wall and the bottom surface of the hole H1 are covered by the conductive film 51. The hole H1 is used to connect the n-type semiconductor film 21 and the wiring 46 of the drive substrate 200, and is provided to penetrate the anti-reflection film 25, the buried layer 34, the interlayer insulating film 35, and the interlayer insulating film 36.

[0146] For example, the hole H2 is provided at a position closer to the end of the light receiving substrate 100 than the hole H1. The hole H2 penetrates the anti-reflection film 25, the buried layer 34, the interlayer insulating film 35, and the interlayer insulating film 36 to reach the wiring 46 of the drive substrate 200. The outside and the imaging element 1 are electrically connected together via the hole H2. The holes H1 and H2 do not need to reach the drive substrate 200. For example, the holes H1 and H2 may reach the wiring provided in the interlayer insulating film 36, and the wiring may be connected to the wiring 46 of the drive substrate 200.

[0147] In the light receiving substrate 100, the interlayer insulating film 36, the interlayer insulating film 35, and the buried layer 34 are arranged in this order from a position close to the drive substrate 200. The interlayer insulating film 36, the interlayer insulating film 35, and the buried layer 34 are arranged from the element region R1 to the peripheral region R2, and the interlayer insulating film 36 and each contact electrode 38 constitute a bonding surface with the drive substrate 200. The bonding surface of the light receiving substrate 100 is arranged in the element region R1 and the peripheral region R2, and the bonding surface in the element region R1 and the bonding surface in the peripheral region R2 constitute the same plane.

[0148] Among the multiple contact electrodes 38 provided in the light receiving substrate 100 , the multiple contact electrodes 38 provided in the peripheral region R2 are not electrically connected to the n-type semiconductor film 21 (photodiode PD) and are all dummy electrodes 38D provided for bonding between the light receiving substrate 100 and the driving substrate 200 .

[0149] In the drive substrate 200, the interlayer insulating film 49, the interlayer insulating film 48, and the interlayer insulating layer 42 are arranged in this order from a position close to the light receiving substrate 100. The interlayer insulating film 49, the interlayer insulating film 48, and the interlayer insulating layer 42 are arranged from the element region R1 to the peripheral region R2, and the interlayer insulating film 49 and each contact electrode 47 constitute a bonding surface with the light receiving substrate 100. The bonding surface of the drive substrate 200 is arranged in the element region R1 and the peripheral region R2, and the bonding surface in the element region R1 and the bonding surface in the peripheral region R2 constitute the same plane.

[0150] Among the plurality of contact electrodes 47 provided in the drive substrate 200, the plurality of contact electrodes 47 provided in the peripheral region R2 are not electrically connected to the n-type semiconductor film 21 (photodiode PD), and are all dummy electrodes 47D provided for bonding between the light receiving substrate 100 and the drive substrate 200. The dummy electrode 47D is provided at a position facing the dummy electrode 38D, and is bonded to the dummy electrode 38D provided at the facing position. This can improve the strength of the peripheral region R2.

[0151] The conductive film 51 is provided from the OPB region to the hole H1 in the peripheral region R2. The conductive film 51 contacts the n-type semiconductor layer 24 in the opening 25H of the anti-reflection film 25 provided in the OPB region, and contacts the wiring 46 of the drive substrate 200 via the hole H1. This allows voltage to be supplied from the drive substrate 200 to the n-type semiconductor layer 24 via the conductive film 51. The conductive film 51 serves as a voltage supply path to the n-type semiconductor layer 24, and also has the same function as the light shielding film to form the OPB region. For example, the conductive film 51 is composed of a metal material containing tungsten (W), aluminum (Al), titanium (Ti), molybdenum (Mo), tantalum (Ta) or copper (Cu). The passivation film 52 may be provided on the conductive film 51.

[0152] <3. Second Implementation Method>

[0153] Fig. 27 An example of a schematic configuration of an imaging device 3 including the imaging element 1 (hereinafter, referred to as “imaging element 1 a ”) according to the above-described embodiment, Modification B, Modification E, and Modification H is shown.

[0154] For example, the imaging device 3 is an electronic device including an imaging device such as a digital camera or a video camera, or a portable terminal device such as a smart phone or a tablet terminal. For example, the imaging device 3 includes an imaging element 1a, an optical system 141, a shutter device 142, a DSP circuit 143, a frame memory 144, a display unit 145, a storage unit 146, an operation unit 147, and a power supply unit 148. In the imaging device 3, the imaging element 1a, the shutter device 142, the DSP circuit 143, the frame memory 144, the display unit 145, the storage unit 146, the operation unit 147, and the power supply unit 148 are connected to each other via a bus 149.

[0155] The imaging element 1a outputs image data (digital value) corresponding to the incident light. The optical system 141 includes one or more lenses, and guides the light (incident light) from the subject to the imaging element 1a to form an image on the light receiving surface of the imaging element 1a. The shutter device 142 is arranged between the optical system 141 and the imaging element 1a, and controls the light irradiation and light shielding period relative to the imaging element 1a. The DSP circuit 143 is a signal processing circuit that processes the image data (digital value) output from the imaging element 1a. The frame memory 144 temporarily holds the image data processed by the DSP circuit 143 in units of frames. For example, the display unit 145 includes a panel-type display device such as a liquid crystal panel or an organic EL (electroluminescent) panel, and displays a moving image or a still image captured by the imaging element 1a. The storage unit 146 records the image data of the moving image or the still image captured by the imaging element 1a in a recording medium such as a semiconductor memory or a hard disk. The operation unit 147 issues operation instructions for various functions of the imaging device 3 according to the user's operation. The power supply unit 148 appropriately supplies various types of power for operation to the imaging element 1 a , the shutter device 142 , the DSP circuit 143 , the frame memory 144 , the display unit 145 , the storage unit 146 , and the operation unit 147 as supply targets.

[0156] Next, an example of an imaging process in the imaging device 3 is given.

[0157] Fig.28 illustrate Figure 3 4 is an example of a flowchart of an imaging operation in the imaging device 3. The user instructs the start of imaging by operating the operating unit 147 (step S401). Then, the operating unit 147 sends an imaging instruction to the imaging element 1a (step S402). In the imaging device 3, the imaging element 1a performs various settings (for example, the above-mentioned image quality adjustment, etc.) upon receiving the imaging instruction (step S403). Thereafter, the imaging element 1a performs imaging in a predetermined imaging mode (step S404). It should be noted that in the imaging device 3, the imaging element 1a repeatedly performs steps S403 and S404 as needed.

[0158] The imaging element 1a outputs the image data obtained by imaging to the DSP circuit 143. As used herein, the image data refers to the data of all pixels of the pixel signal generated based on the charge temporarily held in the floating diffusion FD. The DSP circuit 143 performs predetermined signal processing (e.g., noise reduction processing, etc.) based on the image data input from the imaging element 1a (step S405). The DSP circuit 143 causes the frame memory 144 to hold the image data subjected to the predetermined signal processing, and the frame memory 144 causes the storage unit 146 to store the image data (step S406). In this way, imaging in the imaging device 3 is performed.

[0159] In the present embodiment, the imaging element 1a is applied to the imaging device 3. This can automatically perform image quality adjustment of the imaging element 1a.

[0160] <4. Modification of the Second Implementation Example>

[0161] In the above-mentioned second embodiment, the imaging device 3 may include the imaging element 1 according to the above-mentioned Modification A, Modification C, Modification D, Modification F, Modification G and Modification H (hereinafter, referred to as "imaging element 1b") instead of the imaging element 1a. In this case, for example, Fig.29 As shown, the imaging device 3 may include the image quality control circuit 2. Also in this case, similarly to the above-described application example, the image quality adjustment of the imaging element 1b can be automatically performed.

[0162] <5. Application Examples>

[0163] [Application Example 1]

[0164] The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the embodiments of the present disclosure can be implemented in the form of a device installed on any type of mobile body. Non-limiting examples of mobile bodies can include automobiles, electric vehicles, hybrid vehicles, motorcycles, bicycles, personal mobility devices, airplanes, unmanned aerial vehicles (UAVs), ships, or robots.

[0165] Fig.30 1 is a block diagram showing a schematic configuration example of a vehicle control system as an example of a mobile object control system to which the technology according to the embodiment of the present disclosure can be applied.

[0166] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. Fig.30In the example shown, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. In addition, a microcomputer 12051, a sound / image output unit 12052, and an in-vehicle network interface (I / F) 12053 are shown as functional components of the integrated control unit 12050.

[0167] The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 serves as a control device for the following devices: a drive force generating device such as an internal combustion engine, a drive motor, etc. for generating a drive force for the vehicle; a drive force transmitting mechanism for transmitting the drive force to the wheels; a steering mechanism for adjusting the steering angle of the vehicle; and a braking device for generating a braking force for the vehicle, etc.

[0168] The body system control unit 12020 controls the operation of various devices provided in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lights such as a headlight, a taillight, a brake light, a turn signal light, a fog light, etc. In this case, a radio wave transmitted from a mobile device as a substitute for a key or a signal of various switches may be input to the body system control unit 12020. The body system control unit 12020 receives these input radio waves or signals, and controls a door lock device, a power window device, lights, etc. of the vehicle.

[0169] The vehicle exterior information detection unit 12030 detects information about the exterior of the vehicle including the vehicle control system 12000. For example, the vehicle exterior information detection unit 12030 is connected to the imaging unit 12031. The vehicle exterior information detection unit 12030 causes the imaging unit 12031 to image the exterior of the vehicle and receives the imaged image. Based on the received image, the vehicle exterior information detection unit 12030 may perform a process of detecting objects such as people, vehicles, obstacles, signs, text on the road surface, etc., or a process of detecting the distance to these objects.

[0170] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 may output the electrical signal as an image, or may output the electrical signal as information about the measured distance. In addition, the light received by the imaging unit 12031 may be visible light, or may be invisible light such as infrared rays.

[0171] The in-vehicle information detection unit 12040 detects information about the interior of the vehicle. For example, the in-vehicle information detection unit 12040 is connected to a driver state detection unit 12041 that detects the driver's state. For example, the driver state detection unit 12041 includes a camera that images the driver. Based on the detection information input from the driver state detection unit 12041, the in-vehicle information detection unit 12040 can calculate the driver's fatigue level or the driver's concentration level, or can determine whether the driver is dozing off.

[0172] The microcomputer 12051 can calculate the control target value of the driving force generating device, the steering mechanism or the braking device based on the information about the inside or outside of the vehicle obtained by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, and output the control command to the driving system control unit 12010. For example, the microcomputer 12051 can perform the coordinated control aimed at realizing the functions of the advanced driver assistance system (ADAS), which includes: collision avoidance or collision mitigation of the vehicle, following driving based on the vehicle-to-vehicle distance, vehicle speed maintenance driving, vehicle collision warning or vehicle lane departure warning, etc.

[0173] In addition, the microcomputer 12051 can perform collaborative control intended for autonomous driving, which enables the vehicle to drive autonomously by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the outside or inside of the vehicle obtained by the outside information detection unit 12030 or the inside information detection unit 12040, without relying on the driver's operation.

[0174] In addition, the microcomputer 12051 may output a control command to the body system control unit 12020 based on the information about the exterior of the vehicle obtained by the exterior information detection unit 12030. For example, the microcomputer 12051 may perform cooperative control aimed at preventing glare by controlling the headlights to change from high beam to low beam according to the position of the preceding vehicle or the oncoming vehicle detected by the exterior information detection unit 12030.

[0175] The sound / image output unit 12052 transmits an output signal of at least one of sound and image to an output device capable of visually or auditorily notifying the vehicle's passengers or the outside of the vehicle of information. Fig.30 In the example of FIG. 1 , an audio speaker 12061, a display portion 12062, and an instrument panel 12063 are shown as output devices. For example, the display portion 12062 may include at least one of an in-vehicle display and a head-up display.

[0176] Fig.3112031 is a diagram showing an example of the installation position of the imaging unit 12031.

[0177] exist Fig.31 In the figure, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104 and 12105.

[0178] For example, the imaging units 12101, 12102, 12103, 12104, and 12105 are arranged at positions on the front nose, side mirrors, rear bumper, and rear door of the vehicle 12100, and at positions on the upper portion of the windshield inside the vehicle. The imaging unit 12101 disposed at the front nose and the imaging unit 12105 disposed at the upper portion of the windshield inside the vehicle mainly obtain images in front of the vehicle 12100. The imaging units 12102 and 12103 disposed at the side mirrors mainly obtain images on the sides of the vehicle 12100. The imaging unit 12104 disposed at the rear bumper or rear door mainly obtains images at the rear of the vehicle 12100. The imaging unit 12105 disposed at the upper portion of the windshield inside the vehicle is mainly used to detect vehicles in front, pedestrians, obstacles, signals, traffic signs, lanes, etc.

[0179] By the way, Fig.31 Examples of the shooting ranges of the imaging units 12101 to 12104 are shown. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided at the front nose. Imaging ranges 12112 and 12113 respectively indicate the imaging ranges of the imaging units 12102 and 12103 provided at the side mirrors. Imaging range 12114 indicates the imaging range of the imaging unit 12104 provided at the rear bumper or the rear door. For example, a bird's-eye view image of the vehicle 12100 viewed from above is obtained by superimposing the image data shot by the imaging units 12101 to 12104.

[0180] At least one of the imaging units 12101 to 12104 may have a function of obtaining distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera composed of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0181] For example, the microcomputer 12051 can determine the distance to each three-dimensional object within the imaging range 12111 to 12114 and the time change of the distance (relative speed relative to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104, thereby extracting the nearest three-dimensional object as the leading vehicle, in particular, the three-dimensional object exists on the driving path of the vehicle 12100 and travels in the same direction as the vehicle 12100 at a predetermined speed (e.g., equal to or greater than 0 km / h). In addition, the microcomputer 12051 can pre-set the following distance to be maintained in front of the leading vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. Therefore, cooperative control intended for automatic driving can be performed, which allows the vehicle to travel autonomously without relying on the driver's operation, etc.

[0182] For example, the microcomputer 12051 can classify the three-dimensional object data about the three-dimensional object into three-dimensional object data of two-wheeled vehicles, standard-sized vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on the distance information obtained from the imaging units 12101 to 12104, extract the classified three-dimensional object data, and use the extracted three-dimensional object data to automatically avoid obstacles. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that can be visually identified by the driver of the vehicle 12100 and obstacles that are difficult for the driver of the vehicle 12100 to visually identify. Then, the microcomputer 12051 determines the collision risk representing the risk of collision with each obstacle. In the case where the collision risk is equal to or higher than the set value and therefore there is a possibility of collision, the microcomputer 12051 outputs a warning to the driver via the audio speaker 12061 or the display unit 12062, and performs forced deceleration or avoidance steering via the drive system control unit 12010. The microcomputer 12051 can thereby assist driving to avoid collision.

[0183] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 may identify pedestrians by determining whether there are pedestrians in the captured images of the imaging units 12101 to 12104. For example, such identification of pedestrians is performed by a process of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras and a process of determining whether it is a pedestrian by performing pattern matching processing on a series of feature points representing the contour of the object. When the microcomputer 12051 determines that there are pedestrians in the captured images of the imaging units 12101 to 12104 and thus identifies the pedestrians, the sound / image output unit 12052 controls the display unit 12062 so that the square contour line for emphasis is displayed in a manner superimposed on the identified pedestrian. In addition, the sound / image output unit 12052 may also control the display unit 12062 so that an icon representing a pedestrian or the like is displayed at a desired position.

[0184] An example of a mobile body control system to which the technology according to the embodiment of the present disclosure can be applied has been described above. The technology according to the embodiment of the present disclosure can be applied to the imaging unit 12031 among the above-mentioned components. Specifically, the imaging device 3 can be applied to the imaging unit 12031. Applying the technology according to the embodiment of the present disclosure to the imaging unit 12031 can obtain a captured image with high image quality, thereby being able to perform high-precision control using the captured image in the mobile body control system.

[0185] [Application Example 2]

[0186] Fig.32 : is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to an embodiment of the present disclosure (the present technology) can be applied.

[0187] exist Fig.32 , a state is shown in which an operator (doctor) 11131 is using an endoscopic surgery system 11000 to perform surgery on a patient 11132 on a bed 11133. As shown in the figure, the endoscopic surgery system 11000 includes an endoscope 11100, other surgical tools 11110 such as a pneumoperitoneum tube 11111 and an energy device 11112, a support arm device 11120 supporting the endoscope 11100 thereon, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0188] The endoscope 11100 includes a lens barrel 11101 having an area of ​​a predetermined length from its distal end inserted into a body cavity of a patient 11132, and a camera 11102 connected to the proximal end of the lens barrel 11101. In the illustrated example, the endoscope 11100 including a rigid endoscope having a rigid lens barrel 11101 is illustrated. However, the endoscope 11100 may also include a flexible endoscope having a flexible lens barrel.

[0189] The lens barrel 11101 has an opening at its distal end in which an objective lens is fitted. The light source device 11203 is connected to the endoscope 11100 so that light generated by the light source device 11203 is introduced into the distal end of the lens barrel 11101 through a light guide extending inside the lens barrel 11101, and irradiated onto an observation object in the body cavity of the patient 11132 through the objective lens. It should be noted that the endoscope 11100 may be a forward-looking endoscope, or may be an oblique-looking endoscope or a side-looking endoscope.

[0190] The optical system and the imaging element are arranged inside the camera head 11102 so that the reflected light (observation light) from the observation object is focused on the imaging element through the optical system. The observation light is photoelectrically converted by the imaging element to generate an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image. The image signal is transmitted to the camera control unit (CCU) 11201 as raw (RAW) data.

[0191] The CCU 11201 includes a central processing unit (CPU), a graphics processing unit (GPU), etc., and centrally controls the operations of the endoscope 11100 and the display device 11202. In addition, for example, the CCU 11201 receives an image signal from the camera 11102, and performs various image processing such as development processing (demosaic processing) on ​​the image signal to display an image based on the image signal.

[0192] The display device 11202 displays thereon an image based on an image signal on which image processing has been performed by the CCU 11201 under the control of the CCU 11201 .

[0193] For example, the light source device 11203 includes a light source such as a light emitting diode (LED) and supplies irradiation light for imaging a surgical area to the endoscope 11100 .

[0194] The input device 11204 is an input interface of the endoscopic surgery system 11000. The user can input various information or instructions to the endoscopic surgery system 11000 through the input device 11204. For example, the user may input instructions to change the imaging conditions (type of irradiation light, magnification, focal length, etc.) of the endoscope 11100.

[0195] The treatment instrument control device 11205 controls the driving of the energy device 11112 to burn or cut tissue, seal blood vessels, etc. The pneumoperitoneum device 11206 supplies gas into the body cavity of the patient 11132 through the pneumoperitoneum tube 11111 to expand the body cavity in order to ensure the field of view of the endoscope 11100 and to ensure the working space of the operator. The recorder 11207 is a device capable of recording various information related to the operation. The printer 11208 is a device capable of printing various information related to the operation in various forms such as text, images, or graphics.

[0196] It should be noted that the light source device 11203 that supplies irradiation light when imaging the surgical area to the endoscope 11100 can be composed of a white light source, for example, an LED, a laser light source, or a combination thereof. In the case where the white light source includes a red, green, and blue (RGB) laser light source, since the output intensity and the output timing can be controlled with high precision for each color (each wavelength), the adjustment of the white balance of the captured image can be performed by the light source device 11203. In addition, in this case, if the laser beams from the respective RGB laser light sources are irradiated on the observed object in a time-division manner, and the driving of the imaging element of the camera 11102 is controlled synchronously with the irradiation timing, images corresponding to the respective R, G, and B colors can also be captured in a time-division manner. According to this method, a color image can be obtained even if a color filter is not set for the imaging element.

[0197] In addition, the drive of the light source device 11203 can be controlled so as to change the intensity of the light to be output at predetermined intervals. By controlling the drive of the imaging element of the camera 11102 in synchronization with the timing of the change in light intensity to acquire images in a time-division manner and synthesize the images, a high dynamic range image can be created without underexposed occluded shadows and overexposed highlights.

[0198] In addition, the light source device 11203 can be configured to supply light of a predetermined wavelength band for special light observation. For example, in special light observation, by utilizing the wavelength dependence of light absorption of body tissue, light of a narrower wavelength band than the irradiation light (i.e., white light) during ordinary observation is irradiated, and narrow-band light observation (narrow-band imaging) for imaging predetermined tissues such as blood vessels in the surface layer of the mucosa with high contrast is performed. Alternatively, in special light observation, fluorescence observation for obtaining an image from fluorescence generated by irradiation of excitation light can be performed. In fluorescence observation, fluorescence observation of body tissue (autofluorescence observation) can be performed by irradiating excitation light on body tissue, or a fluorescent image can be obtained by locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating excitation light corresponding to the fluorescence wavelength of the reagent on the body tissue. The light source device 11203 can be configured to supply narrow-band light and / or excitation light suitable for special light observation as described above.

[0199] Fig.33 It is shown Fig.32 A block diagram showing an example of the functional configuration of the camera 11102 and the CCU 11201 shown.

[0200] The camera 11102 includes a lens unit 11401, an imaging unit 11402, a driving unit 11403, a communication unit 11404, and a camera control unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera 11102 and the CCU 11201 are connected via a transmission cable 11400 to communicate with each other.

[0201] The lens unit 11401 is an optical system provided at a connection position with the lens barrel 11101. Observation light entering from the distal end of the lens barrel 11101 is guided to the camera head 11102 and introduced into the lens unit 11401. The lens unit 11401 includes a combination of a plurality of lenses including a zoom lens and a focus lens.

[0202] The number of imaging elements included in the imaging unit 11402 can be one (single-board type) or multiple (multi-board type). For example, in the case where the imaging unit 11402 is constructed as a multi-board type, image signals corresponding to each R, G, and B are generated by the imaging element, and the image signals can be synthesized to obtain a color image. The imaging unit 11402 can also be configured to have a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to a three-dimensional (3D) display. If a 3D display is performed, the operator 11131 can more accurately grasp the depth of the living tissue in the surgical area. It should be noted that in the case where the imaging unit 11402 is constructed as a multi-board type, multiple systems of the lens unit 11401 are set corresponding to the respective imaging elements.

[0203] In addition, the imaging unit 11402 is not necessarily provided on the camera head 11102. For example, the imaging unit 11402 may be provided just behind the objective lens inside the lens barrel 11101.

[0204] The driving unit 11403 includes an actuator, and moves the zoom lens and the focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera control unit 11405. Therefore, the magnification and focus of the image captured by the imaging unit 11402 can be appropriately adjusted.

[0205] The communication unit 11404 includes a communication device for sending and receiving various information to and from the CCU 11201. The communication unit 11404 transmits the image signal acquired from the imaging unit 11402 to the CCU 11201 through the transmission cable 11400 as RAW data.

[0206] In addition, the communication unit 11404 receives a control signal for controlling the driving of the camera 11102 from the CCU 11201, and supplies the control signal to the camera control unit 11405. For example, the control signal includes information related to imaging conditions such as information specifying a frame rate of a captured image, information specifying an exposure value when capturing an image, and / or information specifying a magnification and a focus of a captured image.

[0207] It should be noted that imaging conditions such as frame rate, exposure value, magnification or focus may be specified by the user or may be automatically set based on the acquired image signal by the control unit 11413 of the CCU 11201. In the latter case, an automatic exposure (AE) function, an automatic focus (AF) function, and an automatic white balance (AWB) function are incorporated into the endoscope 11100.

[0208] The camera control unit 11405 controls the driving of the camera 11102 based on the control signal received from the CCU 11201 through the communication unit 11404 .

[0209] The communication unit 11411 includes a communication device for transmitting and receiving various information to and from the camera 11102. The communication unit 11411 receives an image signal transmitted thereto from the camera 11102 through the transmission cable 11400.

[0210] Furthermore, the communication unit 11411 transmits a control signal for controlling the driving of the camera 11102 to the camera 11102. The image signal and the control signal may be transmitted through electrical communication, optical communication, or the like.

[0211] The image processing unit 11412 performs various image processing on the image signal in the form of RAW data transmitted thereto from the camera 11102 .

[0212] The control unit 11413 performs various controls related to imaging of the operation area, etc. through the endoscope 11100 and display of a captured image obtained by imaging the operation area, etc. For example, the control unit 11413 creates a control signal for controlling the driving of the camera head 11102 .

[0213] In addition, the control unit 11413 controls the display device 11202 based on the image signal that has been image-processed by the image processing unit 11412 to display a captured image in which the surgical area, etc., is imaged. At this time, the control unit 11413 can use various image recognition technologies to recognize various objects in the captured image. For example, the control unit 11413 can recognize surgical tools such as surgical forceps, specific living areas, bleeding, fog when using the energy device 11112, etc. by detecting the shape, color, etc. of the edge of the object included in the captured image. When the control unit 11413 controls the display device 11202 to display the captured image, it can use the recognition result to display various surgical support information in a manner overlapping with the image of the surgical area. In the case where the surgical support information is displayed in an overlapping manner and presented to the operator 11131, the burden of the operator 11131 can be reduced and the operator 11131 can reliably perform the operation.

[0214] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 to each other is an electrical signal cable for electrical signal communication, an optical fiber for optical communication, or a composite cable for electrical and optical communication.

[0215] Here, although in the example shown, communication is performed through wired communication using the transmission cable 11400, communication between the camera 11102 and the CCU 11201 may be performed through wireless communication.

[0216] An example of an endoscopic surgical system to which the technology according to the embodiment of the present disclosure is applicable has been described above. For example, in the above-mentioned configuration, the technology according to the embodiment of the present disclosure can be appropriately applied to the imaging unit 11402 provided in the camera head 11102 of the endoscope 11100. Applying the technology according to the embodiment of the present disclosure to the imaging unit 11402 can obtain a captured image with high image quality, so that the endoscope 11100 with high image quality can be provided.

[0217] Although the description of the present disclosure has been given above with reference to the embodiments and their variations, applicable examples and application examples, the present disclosure is not limited to these embodiments, etc., and can be deformed in various ways. It should be noted that the effects recorded herein are merely illustrative. The effects of the present disclosure are not limited to those recorded herein. The present disclosure may have other effects in addition to those recorded herein.

[0218] In addition, for example, the present disclosure may have the following configurations.

[0219] (1) An imaging element, comprising:

[0220] a plurality of sensor pixels each including a photoelectric conversion portion and a readout circuit that outputs a pixel signal based on charges output from the photoelectric conversion portion; and

[0221] A voltage control unit applies a control voltage based on the pixel signal to each photoelectric conversion unit.

[0222] (2) The imaging element according to (1), wherein

[0223] When the pixel signal exceeds a first threshold, the voltage control section makes the control voltage relatively large, and

[0224] When the pixel signal falls below a second threshold value that is smaller than the first threshold value, the voltage control section makes the control voltage relatively small.

[0225] (3) The imaging element according to (1) or (2), wherein

[0226] Each of the sensor pixels further includes a first electrode and a second electrode sandwiching the photoelectric conversion unit, and

[0227] The voltage control section generates a first voltage to be applied to the first electrode and a second voltage to be applied to the second electrode based on the pixel signal so that a potential difference between the first voltage and the second voltage becomes the control voltage.

[0228] (4) The imaging element according to (3), wherein

[0229] Each of the sensor pixels also includes

[0230] a charge holding portion that holds the charge transferred from the photoelectric conversion portion,

[0231] a transfer transistor which is electrically connected to the second electrode and transfers the charge from the photoelectric conversion portion to the charge holding portion, and

[0232] a discharge transistor which is electrically connected to the second electrode and initializes the charge of the photoelectric conversion portion, and

[0233] The voltage control section applies a second voltage to the second electrode when the discharge transistor is turned on.

[0234] (5) The imaging element according to (1) or (2), wherein

[0235] Each of the sensor pixels further comprises:

[0236] a first electrode and a second electrode sandwiching the photoelectric conversion unit,

[0237] a charge holding portion that holds the charge transferred from the photoelectric conversion portion, and

[0238] a transfer transistor which is electrically connected to the second electrode and transfers the charge from the photoelectric conversion portion to the charge holding portion,

[0239] The readout circuit includes a reset transistor for initializing the potential of the charge holding portion, and

[0240] The voltage control section generates a first voltage to be applied to the first electrode based on the pixel signal so that a potential difference between the first voltage and a second voltage of the second electrode applied by the reset transistor when the transfer transistor is in an on state becomes the control voltage.

[0241] (6) The imaging element according to (1) or (2), wherein

[0242] Each of the sensor pixels further includes a charge holding portion that holds the charge transferred from the photoelectric conversion portion,

[0243] The readout circuit includes a reset transistor for initializing the potential of the charge holding portion, and

[0244] The voltage control section generates a first voltage to be applied to the first electrode based on the pixel signal so that a potential difference between the first voltage and a second voltage of the second electrode applied by the reset transistor becomes the control voltage.

[0245] (7) The imaging element according to any one of (1) to (6), further comprising:

[0246] an analog-to-digital conversion circuit, which performs AD conversion on the pixel signal; and

[0247] A range control unit outputs a range setting value based on the pixel signal to the analog-to-digital conversion circuit.

[0248] (8) The imaging element according to (7), wherein

[0249] When the pixel signal exceeds a first threshold, the range control section makes the range setting value relatively large, and

[0250] The range control section makes the range setting value relatively small when the pixel signal falls below a second threshold value that is smaller than the first threshold value.

[0251] (9) The imaging element according to any one of (1) to (6),

[0252] Each of the sensor pixels also includes

[0253] a charge holding portion that holds the charge transferred from the photoelectric conversion portion,

[0254] a transfer transistor that transfers charge from the photoelectric conversion portion to the charge holding portion,

[0255] a switching element connected to the charge holding portion,

[0256] an auxiliary capacitor connected in parallel with the capacitor of the charge holding portion via the switching element, and

[0257] A conversion efficiency control unit controls on / off of the switch element based on the pixel signal.

[0258] (10) The imaging element according to (9), wherein

[0259] When the pixel signal exceeds a first threshold, the conversion efficiency control unit turns off the switch element, and

[0260] The conversion efficiency control section turns on the switching element when the pixel signal falls below a second threshold value that is smaller than the first threshold value.

[0261] (11) An imaging device comprising:

[0262] An imaging element comprising

[0263] a plurality of sensor pixels each including a photoelectric conversion portion and a readout circuit that outputs a pixel signal based on charges output from the photoelectric conversion portion; and

[0264] An image quality control circuit applies a control voltage based on the pixel signal to each photoelectric conversion unit.

[0265] According to the imaging element and the imaging device of each embodiment of the present disclosure, compared with the case where a fixed voltage is applied to each photoelectric conversion unit, a control voltage based on a pixel signal is applied to each photoelectric conversion unit, so that image quality adjustment can be performed according to the brightness of the image data. Therefore, degradation of image quality can be suppressed. It should be noted that the effects of the present disclosure are not necessarily limited to the effects described herein, and can be any effect described herein.

[0266] This application claims the benefit of Japanese Priority Patent Application JP 2019-043786 filed in the Japan Patent Office on Mar. 11, 2019, the entire contents of which are hereby incorporated by reference.

[0267] Those skilled in the art should understand that within the scope of protection of the appended claims or their equivalents, various modifications, combinations, sub-combinations and changes may be made according to design requirements and other factors.

Claims

1. An imaging element, comprising: a plurality of sensor pixels, each of the sensor pixels including a photoelectric conversion portion and a readout circuit that outputs a pixel signal based on the charge output from the photoelectric conversion portion; and a voltage control unit that applies a control voltage based on the pixel signal to each photoelectric conversion unit, wherein Each of the sensor pixels also includes a charge holding portion that holds the charge transferred from the photoelectric conversion portion, a transfer transistor that transfers charge from the photoelectric conversion portion to the charge holding portion, a switching element connected to the charge holding portion, an auxiliary capacitor connected in parallel with the capacitor of the charge holding portion via the switching element, and a conversion efficiency control unit that controls on / off of the switch element based on the pixel signal, wherein When the pixel signal exceeds a first threshold, the conversion efficiency control unit turns off the switch element, and The conversion efficiency control section turns on the switching element when the pixel signal falls below a second threshold value that is smaller than the first threshold value.

2. The imaging element according to claim 1, wherein When the pixel signal exceeds a first threshold, the voltage control section makes the control voltage relatively large, and When the pixel signal falls below a second threshold value that is smaller than the first threshold value, the voltage control section makes the control voltage relatively small.

3. The imaging element according to claim 1 or 2, wherein Each of the sensor pixels further includes a first electrode and a second electrode sandwiching the photoelectric conversion unit, and The voltage control section generates a first voltage to be applied to the first electrode and a second voltage to be applied to the second electrode based on the pixel signal so that a potential difference between the first voltage and the second voltage becomes the control voltage.

4. The imaging element according to claim 3, wherein Each of the sensor pixels further includes a discharge transistor which is electrically connected to the second electrode and initializes the charge of the photoelectric conversion portion, and The voltage control section applies a second voltage to the second electrode when the discharge transistor is turned on.

5. The imaging element according to claim 1 or 2, wherein Each of the sensor pixels further includes a first electrode and a second electrode sandwiching the photoelectric conversion unit. The readout circuit includes a reset transistor for initializing the potential of the charge holding portion, and The voltage control section generates a first voltage to be applied to the first electrode based on the pixel signal so that a potential difference between the first voltage and a second voltage of the second electrode applied by the reset transistor when the transfer transistor is in an on state becomes the control voltage.

6. The imaging element according to claim 1 or 2, further comprising: An analog-to-digital conversion circuit, which performs AD conversion on the pixel signal; and A range control unit outputs a range setting value based on the pixel signal to the analog-to-digital conversion circuit.

7. The imaging element according to claim 6, wherein When the pixel signal exceeds a first threshold, the range control section makes the range setting value relatively large, and The range control section makes the range setting value relatively small when the pixel signal falls below a second threshold value that is smaller than the first threshold value.

8. An imaging device comprising: An imaging element comprising a plurality of sensor pixels, each of the sensor pixels comprising: Photoelectric conversion unit, a readout circuit for outputting a pixel signal based on the charge output from the photoelectric conversion unit, a charge holding portion that holds the charge transferred from the photoelectric conversion portion, a transfer transistor that transfers charge from the photoelectric conversion portion to the charge holding portion, a switching element connected to the charge holding portion, and an auxiliary capacitor connected in parallel with the capacitor of the charge holding portion via the switching element, and An image quality control circuit that applies a control voltage based on the pixel signal to each photoelectric conversion unit and includes a conversion efficiency control unit that controls on / off of the switch element based on the pixel signal, wherein When the pixel signal exceeds a first threshold, the conversion efficiency control unit turns off the switch element, and The conversion efficiency control section turns on the switching element when the pixel signal falls below a second threshold value that is smaller than the first threshold value.

Images