Camera System

Abstract

To further reduce power consumption.SOLUTION: A camera system includes a photoelectric conversion unit including a first electrode, a second electrode, and a photoelectric conversion layer between the first electrode and the second electrode, and a correction circuit that corrects a signal corresponding to a change in the potential of the second electrode according to the amount of incident light. The photoelectric conversion unit has a photoelectric conversion characteristic in which the rate of change of the photoelectric conversion efficiency of the photoelectric conversion unit with respect to a bias voltage when the bias voltage between the first electrode and the second electrode is in a first voltage range is greater than the rate of change of the photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage is in a second voltage range greater than the first voltage range, and a first voltage is supplied to the first electrode such that the bias voltage is in the first voltage range, and the correction circuit corrects the signal such that the change in output with respect to the amount of incident light is linear.SELECTED DRAWING: Figure 21A

Description

[Technical Field]

[0001] The present disclosure relates to camera systems. [Background technology]

[0002] In the field of imaging devices, a configuration is known in which a photoelectric conversion layer is disposed above a semiconductor substrate on which a readout circuit is formed, instead of a photodiode. This configuration is also called a stacked type. For example, Patent Document 1 below discloses an imaging element having an organic photoelectric conversion layer sandwiched between a pixel electrode and a transparent counter electrode above a substrate on which a readout circuit is formed. During operation, a predetermined voltage is applied to the counter electrode.

[0003] The following Patent Document 2 discloses an imaging system having a quantum dot layer as a photoelectric conversion layer, and also discloses that the gain of the quantum dot layer is adjusted by changing the potential difference applied between a transparent electrode and a pixel electrode that sandwich the quantum dot layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-228648 [Patent Document 2] U.S. Patent No. 9,054,246 Summary of the Invention [Problem to be solved by the invention]

[0005] It would be beneficial to further reduce power consumption. [Means for solving the problem]

[0006] According to certain non-limiting exemplary embodiments of the present disclosure, for example, the following is provided:

[0007] a voltage supply circuit that supplies a voltage to one of the first electrode and the second electrode; an output circuit that is electrically connected to the second electrode and outputs a signal according to the potential of the second electrode; and a detection circuit that detects the level of the signal from the output circuit, wherein the photoelectric conversion unit is configured such that, when a bias voltage applied between the first electrode and the second electrode is in a first voltage range, a rate of change in photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage is smaller than the rate of change in photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage is in a second voltage range that is higher than the first voltage range; an imaging device having a photoelectric conversion characteristic that is greater than a rate of change of the photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage, wherein the voltage supply circuit applies a voltage to one of the first electrode and the second electrode so that a potential difference between the first electrode and the second electrode becomes a first potential difference when the level detected by the detection circuit is equal to or greater than a first threshold, and applies a voltage to the one of the first electrode and the second electrode so that a potential difference between the first electrode and the second electrode becomes a second potential difference that is greater than the first potential difference when the level detected by the detection circuit is lower than a second threshold that is equal to or less than the first threshold.

[0008] The generic or specific aspects may be realized as an element, a device, a system, an integrated circuit, a method, or a computer program, or may be realized as any combination of an element, a device, an apparatus, a system, an integrated circuit, a method, and a computer program.

[0009] Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. The benefits and / or advantages are provided individually by the various embodiments or features disclosed in the specification and drawings, and not all are required to obtain one or more of them. [Effects of the Invention]

[0010] According to certain embodiments of the present disclosure, power consumption can be further reduced. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram schematically illustrating an exemplary configuration of an imaging device according to a first embodiment of the present disclosure. [Figure 2] 2 is a diagram showing an exemplary circuit configuration of the imaging device 100A shown in FIG. [Figure 3A] 1 is a cross-sectional view schematically illustrating an exemplary device structure of a pixel Px. [Figure 3B] 10 is a schematic cross-sectional view for explaining the operation of a pixel Px when electrons are used as signal charges. FIG. [Figure 4] FIG. 3 is a diagram showing a typical example of the photoelectric conversion characteristics of the photoelectric conversion layer 13. [Figure 5] FIG. 4 is a diagram for explaining an example of a method for determining specific ranges of a first voltage range and a second voltage range. [Figure 6] FIG. 10 is a diagram for explaining another example of a method for determining specific ranges of the first voltage range and the second voltage range. [Figure 7] FIG. 10 is a diagram for explaining yet another example of a method for determining specific ranges of the first voltage range and the second voltage range. [Figure 8] 10 is a schematic flowchart showing a first exemplary operation of the imaging device 100A. [Figure 9] 10 is a schematic cross-sectional view illustrating a change in photoelectric conversion efficiency η with respect to a change in illuminance when a voltage of 2 V is applied to the counter electrode 11 as a first voltage V1. FIG. [Figure 10] This is a schematic cross-sectional view to explain the change in photoelectric conversion efficiency η with changes in illuminance when a voltage of 2 V is applied to the opposing electrode 11 as a first voltage V1, and schematically shows the state in which holes are accumulated in the impurity region 111. [Figure 11] 2 is a diagram schematically showing a typical example of a change in the level of a signal from an output circuit 20 in response to a change in the amount of light incident on a photoelectric conversion unit 10. FIG. [Figure 12]10 is a diagram schematically illustrating a state in which a potential difference ΔV is increased by applying a second voltage V2 from a voltage supply circuit 150 to a voltage line 152. FIG. [Figure 13] 10 is a diagram schematically showing a typical example of a change in the level of a signal from an output circuit 20 in response to a change in the amount of light incident on a photoelectric conversion unit 10 when a second voltage V2 is applied to a counter electrode 11. FIG. [Figure 14] 10 is a schematic cross-sectional view showing a configuration in which a third electrode 15 is disposed between two pixel electrodes 12 adjacent to each other. [Figure 15] 1 is a schematic plan view showing an example of the positional relationship between a pixel electrode 12 and a third electrode 15 when viewed from the counter electrode 11 side. [Figure 16] 10 is a schematic cross-sectional view for explaining the mechanism by which the effective photoelectric conversion efficiency is further reduced by applying a predetermined voltage to the third electrode 15. FIG. [Figure 17] This figure schematically shows another typical example of changes in the level of the signal from the output circuit 20 in response to changes in the amount of light incident on the photoelectric conversion unit 10 when a first voltage V1 is applied to the opposing electrode 11 and when a second voltage V2 is applied to the opposing electrode 11. [Figure 18] FIG. 10 is a schematic cross-sectional view for explaining the operation of pixel Px under high illuminance in the second operation example, showing the state in which a voltage of about 6 V, which is a medium voltage, is applied to the counter electrode 11 as the first voltage V1. [Figure 19] FIG. 10 is a schematic cross-sectional view for explaining the operation of pixel Px under low illuminance in the second operation example, showing a state in which a voltage of 12 V is applied to the counter electrode 11 as the second voltage V2. [Figure 20A] FIG. 10 is a diagram illustrating an exemplary circuit configuration of an imaging device according to a modified example of the first embodiment. [Figure 20B] FIG. 10 is a diagram illustrating an exemplary circuit configuration of an imaging device according to another modified example of the first embodiment. [Figure 21A] FIG. 10 is a diagram schematically illustrating an exemplary configuration of a camera system according to a second embodiment of the present disclosure. [Figure 21B]FIG. 10 is a diagram schematically illustrating another exemplary configuration of a camera system according to the second embodiment of the present disclosure. [Figure 22] FIG. 10 is a diagram schematically illustrating yet another exemplary configuration of a camera system according to the second embodiment of the present disclosure. [Figure 23] FIG. 10 is a diagram showing a modified example of the light amount detecting device. [Figure 24] FIG. 10 is a diagram schematically illustrating yet another exemplary configuration of a camera system according to the second embodiment of the present disclosure. [Figure 25] 10 is a diagram for explaining the relationship between the timing of switching between the first voltage V1 and the second voltage V2 and the change in the level of the signal acquired by the detection circuit 130A that accompanies the voltage switching. FIG. [Figure 26] 10 is a diagram showing another example of the timing of switching between the first voltage V1 and the second voltage V2. FIG. [Figure 27] FIG. 10 is a diagram showing yet another example of the timing of switching between the first voltage V1 and the second voltage V2. [Figure 28] FIG. 10 is a diagram for explaining the relationship between the timing of switching between the first voltage V1 and the second voltage V2 and the change in the level of the signal acquired by the detection circuit 130A due to the voltage switching when a global shutter is applied by controlling the potential difference ΔV. [Figure 29] 10 is a diagram illustrating an example of the relationship between the timing of switching between the first voltage V1 and the second voltage V2 and the output from the imaging device 100A. FIG. [Figure 30] 10A and 10B are diagrams illustrating an example of application of mask processing when switching between the first voltage V1 and the second voltage V2 is performed during a row scanning period for signal readout. [Figure 31] 10A and 10B are diagrams for explaining an example of a processing sequence in automatic exposure setting that can be applied to an imaging device and a camera system according to an embodiment of the present disclosure. [Figure 32] FIG. 10 is a schematic plan view for explaining an example in which a region including the photoelectric conversion units 10 of some or all of the pixels Px included in the imaging region Rm is used as a detection region Rd for the amount of exposure light. [Figure 33] 10A and 10B are diagrams illustrating an example of a process for changing a voltage output from a voltage supply circuit in accordance with a detected amount of exposure. [Figure 34] 10A and 10B are diagrams illustrating another example of a process for changing the voltage output from the voltage supply circuit in accordance with the detected amount of exposure. [Figure 35] FIG. 10 is a diagram illustrating yet another example of a process for changing the voltage output from the voltage supply circuit in accordance with the detected amount of exposure. [Figure 36] FIG. 10 is a diagram schematically illustrating an example of a change in the output of a detection circuit 130A in response to an increase in the amount of exposure. [Figure 37] FIG. 1 is a block diagram illustrating an outline of linearity compensation processing. [Figure 38] FIG. 10 is a diagram illustrating an example of a correction table. [Figure 39] 10A and 10B are diagrams for explaining differences in linearity deviation between imaging devices or camera systems. [Figure 40] FIG. 1 is a block diagram illustrating an outline of linearity compensation processing that cancels differences between image pickup devices or camera systems. [Figure 41] FIG. 10 is a diagram showing an example of a correction table stored in a memory 162 of the imaging device of Sample 1. [Figure 42] FIG. 10 is a diagram showing an example of a correction table stored in a memory 162 of the imaging device of sample 2. [Figure 43] FIG. 10 is a diagram showing another example of the correction table stored in the memory 162. [Figure 44] FIG. 44 is a diagram showing a plot of output values ​​described in the correction table of FIG. 43. [Figure 45] FIG. 10 is a diagram illustrating an outline of linearity compensation processing including interpolation processing. DETAILED DESCRIPTION OF THE INVENTION

[0012] As described in Patent Document 1, a relatively high voltage exceeding the power supply voltage may be required for the voltage applied to the counter electrode in a stacked-type configuration. It would be beneficial to be able to further reduce power consumption.

[0013] An outline of one aspect of the present disclosure is as follows.

[0014] [Item 1] a photoelectric conversion unit including a first electrode, a second electrode, and a photoelectric conversion layer located between the first electrode and the second electrode; a voltage supply circuit that supplies a voltage to one of the first electrode and the second electrode; an output circuit electrically connected to the second electrode and configured to output a signal corresponding to the potential of the second electrode; a detection circuit that detects the level of the signal from the output circuit; Equipped with the photoelectric conversion unit has photoelectric conversion characteristics in which a rate of change of the photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage applied between the first electrode and the second electrode is in a first voltage range is greater than a rate of change of the photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage is in a second voltage range higher than the first voltage range; The voltage supply circuit is applying a voltage to one of the first electrode and the second electrode so that a potential difference between the first electrode and the second electrode becomes a first potential difference when the level detected by the detection circuit is equal to or greater than a first threshold; An imaging device that applies a voltage to one of the first electrode and the second electrode so that the potential difference between the first electrode and the second electrode becomes a second potential difference greater than the first potential difference when the level detected by the detection circuit is lower than a second threshold that is equal to or less than the first threshold.

[0015] [Item 2] The voltage supply circuit is applying a first voltage to one of the first electrode and the second electrode when the level detected by the detection circuit is equal to or greater than a first threshold; Item 1. An imaging device according to item 1, wherein a second voltage higher than the first voltage is applied to one of the first electrode and the second electrode when the level detected by the detection circuit is lower than a second threshold.

[0016] [Item 3] An imaging device described in item 2, wherein the potential of the first electrode is higher than the potential of the second electrode both when a first voltage is applied to one of the first electrode and the second electrode and when a second voltage is applied to one of the first electrode and the second electrode.

[0017] [Item 4] Item 2. The imaging device according to item 2 or 3, wherein, in a graph of the photoelectric conversion efficiency of the photoelectric conversion unit versus bias voltage, when the bias voltage value corresponding to the intersection of a first tangent line at the point where the photoelectric conversion efficiency rises from 0 and a second tangent line at the point where the bias voltage is at its maximum value during operation is defined as Vt, the first voltage range is a voltage range less than Vt.

[0018] [Item 5] Item 2. The imaging device according to item 2 or 3, wherein, in a graph of the photoelectric conversion efficiency of the photoelectric conversion unit versus bias voltage, when the bias voltage value corresponding to the intersection of a first tangent line at a point where the photoelectric conversion efficiency value is 0.06 and a second tangent line at a point where the bias voltage is at its maximum value during operation is defined as Vt, the first voltage range is a voltage range less than Vt.

[0019] [Item 6] 4. The imaging device according to item 2 or 3, wherein the second voltage range is a voltage range in which a change in photoelectric conversion efficiency with a change of 1 V in the bias voltage is less than 10%.

[0020] [Item 7] 4. The imaging device according to item 2 or 3, wherein the second voltage range is a voltage range in which the photoelectric conversion efficiency is 0.7 or higher.

[0021] [Item 8] 8. The imaging device according to any one of items 4 to 7, wherein a first efficiency, which is the photoelectric conversion efficiency of the photoelectric conversion unit when a first voltage is supplied, is lower than a second efficiency, which is the photoelectric conversion efficiency of the photoelectric conversion unit when a second voltage is supplied.

[0022] [Item 9] the first voltage is a voltage within a first voltage range; Item 9. The imaging device of item 8, wherein the second voltage is a voltage within a second voltage range.

[0023] [Item 10] 10. The imaging device of claim 9, wherein the ratio of the second voltage to the first voltage is greater than the ratio of the second efficiency to the first efficiency.

[0024] [Item 11] Item 11. The imaging device according to item 10, wherein the ratio of the second efficiency to the first efficiency is 1.25 or more and 100 or less.

[0025] [Item 12] Item 9. The imaging device of item 8, wherein the first voltage and the second voltage are voltages within a second voltage range.

[0026] [Item 13] Item 13. The imaging device according to item 12, wherein the ratio of the second efficiency to the first efficiency is 1 or more and 1.25 or less.

[0027] [Item 14] a photoelectric conversion unit including a first electrode, a second electrode, and a photoelectric conversion layer located between the first electrode and the second electrode; a voltage supply circuit that supplies a voltage to one of the first electrode and the second electrode; an output circuit electrically connected to the second electrode and outputting a signal according to the potential of the second electrode; an imaging device having a light amount detection device that detects the amount of light incident on the photoelectric conversion unit; Equipped with the photoelectric conversion unit has photoelectric conversion characteristics in which a rate of change of the photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage applied between the first electrode and the second electrode is in a first voltage range is greater than a rate of change of the photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage is in a second voltage range higher than the first voltage range; The voltage supply circuit is applying a voltage to one of the first electrode and the second electrode so that a potential difference between the first electrode and the second electrode becomes a first potential difference when the amount of light detected by the light amount detection device is equal to or greater than a first light amount; A camera system that applies a voltage to one of the first electrode and the second electrode so that a potential difference between the first electrode and the second electrode becomes a second potential difference greater than the first potential difference when the amount of light detected by the light amount detection device is smaller than a second light amount that is equal to or less than the first light amount.

[0028] [Item 15] A method for driving an imaging device having a photoelectric conversion unit including a first electrode, a second electrode, and a photoelectric conversion layer located between the first electrode and the second electrode, the method comprising: applying a voltage to one of the first electrode and the second electrode so that a potential difference between the first electrode and the second electrode becomes a first potential difference when the amount of light incident on the photoelectric conversion unit is equal to or greater than a first light amount; A method for driving an imaging device, in which, when the amount of light incident on a photoelectric conversion unit is smaller than a second amount of light that is equal to or smaller than a first amount of light, a voltage is applied to one of the first electrode and the second electrode so that the potential difference between the first electrode and the second electrode becomes a second potential difference that is larger than the first potential difference.

[0029] [Item 16] a photoelectric conversion unit including a first electrode, a second electrode, and a photoelectric conversion layer located between the first electrode and the second electrode; a voltage supply circuit electrically connected to one of the first electrode and the second electrode; an output circuit electrically connected to the second electrode and configured to output a signal corresponding to the potential of the second electrode; a detection circuit that detects the level of the signal from the output circuit; Equipped with a rate of change in the photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage applied between the first electrode and the second electrode is in a first voltage range is greater than when the bias voltage is in a second voltage range higher than the first voltage range; An imaging device, wherein the voltage supply circuit applies a voltage to one of the first electrode and the second electrode so that the potential difference between the first electrode and the second electrode becomes a first potential difference when the level detected by the detection circuit is equal to or higher than a predetermined threshold, and applies a voltage to one of the first electrode and the second electrode so that the potential difference between the first electrode and the second electrode becomes a second potential difference that is larger than the first potential difference when the level detected by the detection circuit is lower than the threshold.

[0030] According to the configuration of item 16, in high-illuminance situations, the bias voltage applied between the first electrode and the second electrode is reduced, thereby reducing the sensitivity of the photoelectric conversion unit. In other words, an ND filter function is realized through electrical control. This can also be expected to reduce power consumption.

[0031] [Item 17] Item 17. An imaging device according to item 16, wherein the voltage supply circuit applies a first voltage to one of the first electrode and the second electrode when the level detected by the detection circuit is equal to or greater than a threshold, and applies a second voltage higher than the first voltage to one of the first electrode and the second electrode when the level detected by the detection circuit is lower than the threshold.

[0032] According to the configuration of item 17, in a high illuminance situation, the voltage supply circuit selectively applies the relatively low first voltage of the different voltages to the photoelectric conversion unit, which makes it possible to reduce power consumption compared to a configuration in which a relatively high voltage of around 10 V is applied to the photoelectric conversion unit regardless of the illuminance.

[0033] [Item 18] A state in which a first voltage is applied to one of the first electrode and the second electrode, and Item 18. An imaging device according to item 17, wherein the potential of the first electrode is higher than the potential of the second electrode in both states where the second voltage is applied to one of the second electrodes.

[0034] According to the configuration of item 18, positive charges generated by photoelectric conversion can be collected by the second electrode, and holes can be accumulated in the charge accumulation region as signal charges. Furthermore, the potential of the charge accumulation region gradually increases as the signal charges continue to accumulate, so that the effective bias voltage applied to the photoelectric conversion layer can be made smaller than the value of the second voltage.

[0035] [Item 19] Item 17 or 18. The imaging device according to item 17 or 18, wherein, in a graph of the photoelectric conversion efficiency of the photoelectric conversion unit versus bias voltage, when the bias voltage value corresponding to the intersection of a first tangent line at the point where the photoelectric conversion efficiency rises from 0 and a second tangent line at the point where the bias voltage is at its maximum value during operation is Vt, the first voltage range is a voltage range less than Vt.

[0036] [Item 20] Item 17 or 18. The imaging device according to item 17 or 18, wherein, in a graph of the photoelectric conversion efficiency of the photoelectric conversion unit versus bias voltage, when the bias voltage value corresponding to the intersection of a first tangent line at a point where the photoelectric conversion efficiency value is 0.06 and a second tangent line at a point where the bias voltage is at its maximum value during operation is defined as Vt, the first voltage range is a voltage range less than Vt.

[0037] [Item 21] Item 19. The imaging device according to item 17 or 18, wherein the second voltage range is a voltage range in which a change in photoelectric conversion efficiency with a 1 V change in bias voltage is less than 10%.

[0038] [Item 22] Item 19. The imaging device according to item 17 or 18, wherein the second voltage range is a voltage range in which the photoelectric conversion efficiency is 0.7 or more.

[0039] According to the configuration of item 22, it is easy to establish a correspondence between the magnitude of the bias voltage applied between the first electrode and the second electrode and the ISO value.

[0040] [Item 23] An imaging device described in any one of items 19 to 22, wherein a first efficiency, which is the photoelectric conversion efficiency of the photoelectric conversion unit when a first voltage is supplied, is lower than a second efficiency, which is the photoelectric conversion efficiency of the photoelectric conversion unit when a second voltage is supplied.

[0041] According to the configuration of item 23, the sensitivity of the pixel can be reduced by applying a relatively low first voltage V1 to the photoelectric conversion unit to reduce the potential difference between the first electrode and the second electrode.

[0042] [Item 24] the first voltage is a voltage within a first voltage range; Item 24. The imaging device of item 23, wherein the second voltage is a voltage within a second voltage range.

[0043] According to the configuration of item 24, the signal level can be automatically reduced in response to an increase in the amount of light, thereby achieving the effect of expanding the dynamic range in directions with high illuminance.

[0044] [Item 25] Item 25. The imaging device of item 24, wherein the ratio of the second voltage to the first voltage is greater than the ratio of the second efficiency to the first efficiency.

[0045] [Item 26] Item 26. The imaging device according to item 25, wherein the ratio of the second efficiency to the first efficiency is 1.25 or greater.

[0046] [Item 27] Item 24. The imaging device of item 23, wherein the first voltage and the second voltage are voltages within a second voltage range.

[0047] The configuration of item 27 has the advantage that high-voltage elements are not required, making it easier to ensure reliability, and power saving and high-speed driving can be expected when the first voltage is supplied.

[0048] [Item 28] Item 28. The imaging device according to item 27, wherein the ratio of the second efficiency to the first efficiency is 1 or more and 1.25 or less.

[0049] [Item 29] a charge storage unit electrically connected to the second electrode, the charge storage unit temporarily storing the charges collected by the second electrode; 29. The imaging device according to any one of items 16 to 28, wherein the potential of the charge storage section increases as charge accumulates in the charge storage section.

[0050] According to the configuration of Item 29, the effective bias voltage applied to the photoelectric conversion layer changes depending on the illuminance. Therefore, when the voltage supply circuit outputs the first voltage in the first voltage range, the effect of expanding the dynamic range is obtained. Furthermore, when the first voltage and the second voltage are selected from the second voltage range, high-voltage elements and element isolation regions are not required, making it easier to ensure reliability.

[0051] [Item 30] a plurality of pixels each having a photoelectric conversion unit and an output circuit; the plurality of pixels includes a first pixel and a second pixel disposed adjacent to the first pixel; 30. An imaging device described in any one of items 16 to 29, further comprising a third electrode located between the second electrode of the first pixel and the second electrode of the second pixel and electrically insulated from the second electrode of the first pixel and the second electrode of the second pixel.

[0052] According to the configuration of Item 30, by adjusting the potential of the third electrode, it is possible to preferentially collect the charges generated near the boundary between the two pixels by the third electrode. As a result, it is possible to further reduce the effective photoelectric conversion efficiency and further expand the dynamic range in the direction of high illuminance.

[0053] [Item 31] an imaging device having a photoelectric conversion unit including a first electrode, a second electrode, and a photoelectric conversion layer located between the first electrode and the second electrode; a voltage supply circuit electrically connected to one of the first electrode and the second electrode; Equipped with The imaging device an output circuit electrically connected to the second electrode and configured to output a signal corresponding to the potential of the second electrode; a detection circuit that detects the level of the signal from the output circuit; and a rate of change in the photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage applied between the first electrode and the second electrode is in a first voltage range is greater than when the bias voltage is in a second voltage range higher than the first voltage range; The voltage supply circuit is applying a voltage to one of the first electrode and the second electrode so that a potential difference between the first electrode and the second electrode becomes a first potential difference when the level detected by the detection circuit is equal to or greater than a predetermined threshold; A camera system that applies a voltage to one of the first electrode and the second electrode so that a potential difference between the first electrode and the second electrode becomes a second potential difference greater than the first potential difference when the level detected by the detection circuit is lower than a threshold value.

[0054] According to the configuration of item 31, the same effect as that of item 16 can be obtained.

[0055] [Item 32] Item 32. A camera system as described in Item 31, wherein the voltage supply circuit applies a first voltage to one of the first electrode and the second electrode when the level detected by the detection circuit is greater than or equal to a threshold, and applies a second voltage higher than the first voltage to one of the first electrode and the second electrode when the level detected by the detection circuit is lower than the threshold.

[0056] According to the configuration of item 32, the same effect as that of item 17 can be obtained.

[0057] [Item 33] an imaging device having a photoelectric conversion unit including a first electrode, a second electrode, and a photoelectric conversion layer located between the first electrode and the second electrode; a light amount detection device that detects the amount of light incident on the photoelectric conversion unit; Equipped with The imaging device an output circuit electrically connected to the second electrode and configured to output a signal corresponding to the potential of the second electrode; a voltage supply circuit electrically connected to one of the first electrode and the second electrode; and a rate of change in the photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage applied between the first electrode and the second electrode is in a first voltage range is greater than when the bias voltage is in a second voltage range higher than the first voltage range; The voltage supply circuit is applying a voltage to one of the first electrode and the second electrode so that a potential difference between the first electrode and the second electrode becomes a first potential difference when the amount of light detected by the light amount detection device is equal to or greater than a predetermined amount of light; A camera system that applies a voltage to one of the first electrode and the second electrode so that the potential difference between the first electrode and the second electrode becomes a second potential difference that is larger than the first potential difference when the amount of light detected by the light amount detection device is smaller than a predetermined amount of light.

[0058] According to the configuration of item 33, the same effect as that of item 16 can be obtained.

[0059] [Item 34] an imaging device having a photoelectric conversion unit including a first electrode, a second electrode, and a photoelectric conversion layer located between the first electrode and the second electrode; a voltage supply circuit electrically connected to one of the first electrode and the second electrode; a light amount detection device that detects the amount of light incident on the photoelectric conversion unit; Equipped with a rate of change in the photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage applied between the first electrode and the second electrode is in a first voltage range is greater than when the bias voltage is in a second voltage range higher than the first voltage range; The imaging device is electrically connected to the second electrode and outputs a signal corresponding to the potential of the second electrode. further comprising a power circuit; The voltage supply circuit is applying a voltage to one of the first electrode and the second electrode so that a potential difference between the first electrode and the second electrode becomes a first potential difference when the amount of light detected by the light amount detection device is equal to or greater than a predetermined amount of light; A camera system that applies a voltage to one of the first electrode and the second electrode so that the potential difference between the first electrode and the second electrode becomes a second potential difference that is larger than the first potential difference when the amount of light detected by the light amount detection device is smaller than a predetermined amount of light.

[0060] According to the configuration of item 34, the same effect as that of item 16 can be obtained.

[0061] [Item 35] 35. A camera system according to item 33 or 34, wherein the light amount detection device includes a light amount detection circuit that detects the level of a signal from the output circuit.

[0062] According to the configuration of item 35, information regarding the amount of light incident on the photoelectric conversion unit can be obtained by detecting the level of the signal output from the pixel.

[0063] [Item 36] 36. A camera system according to any one of items 33 to 35, wherein the voltage supply circuit applies a first voltage to one of the first electrode and the second electrode when the amount of light detected by the light amount detection device is equal to or greater than a predetermined amount of light, and applies a second voltage higher than the first voltage to one of the first electrode and the second electrode when the amount of light detected by the light amount detection device is less than the predetermined amount of light.

[0064] According to the configuration of item 36, the same effect as that of item 17 can be obtained.

[0065] [Item 37] A camera system as described in item 32 or 36, wherein the potential of the first electrode is higher than the potential of the second electrode both in a state where a first voltage is applied to one of the first electrode and the second electrode and in a state where a second voltage is applied to one of the first electrode and the second electrode.

[0066] According to the configuration of item 37, the same effect as that of item 18 can be obtained.

[0067] [Item 38] Item 38. A camera system according to item 32, 36, or 37, wherein, in a graph of the photoelectric conversion efficiency of the photoelectric conversion unit versus bias voltage, when the bias voltage value corresponding to the intersection of a first tangent line at the point where the photoelectric conversion efficiency rises from 0 and a second tangent line at the point where the bias voltage is at its maximum value during operation is defined as Vt, the first voltage range is a voltage range less than Vt.

[0068] [Item 39] Item 38. A camera system according to item 32, 36, or 37, wherein, in a graph of the photoelectric conversion efficiency of the photoelectric conversion unit versus bias voltage, when the bias voltage value corresponding to the intersection of a first tangent line at a point where the photoelectric conversion efficiency value is 0.06 and a second tangent line at a point where the bias voltage is at its maximum value during operation is defined as Vt, the first voltage range is a voltage range less than Vt.

[0069] [Item 40] Item 38. The camera system of item 32, 36, or 37, wherein the second voltage range is a voltage range in which the change in photoelectric conversion efficiency for a 1 V change in bias voltage is less than 10%.

[0070] [Item 41] Item 38. The camera system of item 32, 36, or 37, wherein the second voltage range is a voltage range in which the photoelectric conversion efficiency is 0.7 or higher.

[0071] According to the configuration of item 41, the same effect as that of item 22 can be obtained.

[0072] [Item 42] A camera system described in any one of items 38 to 41, wherein a first efficiency, which is the photoelectric conversion efficiency of the photoelectric conversion unit when a first voltage is supplied, is lower than a second efficiency, which is the photoelectric conversion efficiency of the photoelectric conversion unit when a second voltage is supplied.

[0073] According to the configuration of item 42, the same effect as that of item 23 can be obtained.

[0074] [Item 43] the first voltage is a voltage within a first voltage range; Item 43. The camera system of item 42, wherein the second voltage is a voltage within a second voltage range.

[0075] According to the configuration of item 43, the same effect as that of item 24 can be obtained.

[0076] [Item 44] Item 44. The camera system of item 43, wherein the ratio of the second voltage to the first voltage is greater than the ratio of the second efficiency to the first efficiency.

[0077] [Item 45] Item 45. The camera system of item 44, wherein the ratio of the second efficiency to the first efficiency is 1.25 or greater.

[0078] [Item 46] Item 43. The camera system of item 42, wherein the first voltage and the second voltage are voltages within a second voltage range.

[0079] According to the configuration of item 46, the same effect as that of item 27 can be obtained.

[0080] [Item 47] Item 47. The camera system of item 46, wherein the ratio of the second efficiency to the first efficiency is greater than or equal to 1 and less than or equal to 1.25.

[0081] [Item 48] a charge storage unit electrically connected to the second electrode, the charge storage unit temporarily storing the charges collected by the second electrode; 48. The camera system according to any one of items 31 to 47, wherein the potential of the charge storage section increases as charge accumulates in the charge storage section.

[0082] According to the configuration of item 48, the same effect as that of item 29 can be obtained.

[0083] [Item 49] The imaging device includes a plurality of pixels, each of which has a photoelectric conversion unit and an output circuit; the plurality of pixels includes a first pixel and a second pixel disposed adjacent to the first pixel; 49. The camera system of any one of items 31 to 48, wherein the imaging device further comprises a third electrode located between the second electrode of the first pixel and the second electrode of the second pixel and electrically insulated from the second electrode of the first pixel and the second electrode of the second pixel.

[0084] According to the configuration of item 49, the same effect as that of item 30 can be obtained.

[0085] [Item 50] A method for driving an imaging device having a photoelectric conversion unit including a first electrode, a second electrode, and a photoelectric conversion layer located between the first electrode and the second electrode, the method comprising: A method for driving an imaging device, in which, when the amount of light incident on the photoelectric conversion unit is equal to or greater than a predetermined amount of light, a voltage is applied to one of the first electrode and the second electrode so that the potential difference between the first electrode and the second electrode becomes a first potential difference, and, when the amount of light incident on the photoelectric conversion unit is less than the predetermined amount of light, a voltage is applied to one of the first electrode and the second electrode so that the potential difference between the first electrode and the second electrode becomes a second potential difference that is greater than the first potential difference.

[0086] According to the configuration of item 50, a state as if an ND filter were inserted can be realized by electrical control.

[0087] [Item 51] A method for driving an imaging device described in item 50, wherein a first voltage is applied to one of the first electrode and the second electrode when the amount of light incident on the photoelectric conversion unit is greater than or equal to a predetermined amount of light, and a second voltage higher than the first voltage is applied to one of the first electrode and the second electrode when the amount of light incident on the photoelectric conversion unit is less than the predetermined amount of light.

[0088] According to the configuration of item 51, the same effect as that of item 17 can be obtained.

[0089] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component arrangements and connection forms, steps, and step orders shown in the following embodiments are merely examples and are not intended to limit the present disclosure. The various aspects described in this specification can be combined with each other as long as no contradiction occurs. Furthermore, among the components in the following embodiments, components that are not recited in independent claims that represent the highest concept are described as optional components. In the following description, components having substantially the same functions are denoted by common reference symbols, and their description may be omitted. Furthermore, to avoid overly complicated drawings, illustration of some elements may be omitted.

[0090] (First embodiment) Fig. 1 schematically illustrates the configuration of an imaging device according to a first embodiment of the present disclosure. The imaging device 100A illustrated in Fig. 1 includes a plurality of pixels Px, each of which includes a photoelectric conversion unit supported on a semiconductor substrate 110. Although not illustrated in Fig. 1, the semiconductor substrate 110 includes a plurality of output circuits formed corresponding to the pixels Px.

[0091] The plurality of pixels Px are arranged, for example, two-dimensionally on the semiconductor substrate 110 to form an imaging area. The number and arrangement of the pixels Px are not limited to the example shown in Fig. 1 and are arbitrary. For example, by arranging the plurality of pixels Px one-dimensionally, the imaging device 100A can be used as a line sensor.

[0092] As will be described in detail later with reference to the drawings, the photoelectric conversion unit of each pixel Px has a pixel electrode, a light-transmitting counter electrode, and a photoelectric conversion layer sandwiched between these electrodes. Typically, a plurality of pixel electrodes are arranged in the imaging region corresponding to each pixel Px, whereas the counter electrode is provided in the form of a single continuous electrode layer between the plurality of pixels Px. In other words, the potential of the counter electrode is typically common between the plurality of pixels Px. Similarly, for the photoelectric conversion layer, a single continuous photoelectric conversion structure can be shared between the plurality of pixels Px. In other words, each pixel P The x photoelectric conversion portion includes a part of a single continuous translucent electrode and a part of a single continuous photoelectric conversion structure between the plurality of pixels Px.

[0093] In the configuration illustrated in FIG. 1, the imaging device 100A has a row signal line R i a row scanning circuit 120 connected to each pixel Px via an output signal line S j and a detection circuit 130A connected to each pixel Px via a row signal line R. Here, the subscripts m and n attached to the reference symbols in FIG. 1 independently represent integers of 1 or greater. i are provided for each row of a plurality of pixels Px and are electrically connected to one or more pixels Px belonging to the same row. For simplicity, in FIG. 1, row signal lines R are used as signal lines connected to the row scanning circuit 120. i is shown as a representative example, but two or more signal lines may be provided for each row of multiple pixels Px. j is provided for each column of pixels Px and is electrically connected to the output circuit of one or more pixels Px belonging to the same column. j Each of these is connected to a detection circuit 130A.

[0094] The detection circuit 130A typically includes, as part thereof, circuits for performing noise suppression signal processing typified by correlated double sampling, analog-to-digital conversion, etc. Pixel signals representing the image of the subject are read out as outputs of the detection circuit 130A to the outside of the image pickup device 100A.

[0095] Here, the detection circuit 130A is connected to the output signal line S j In this example, the detection circuit 130A is connected to a reference line 132. The reference line 132 is connected to a predetermined voltage V ref The detection circuit 130A detects, for example, the level of the output signal from the pixel Px of each column, that is, the level of each output signal line S jThe input signal may have one or more comparators 134 that output a comparison result between the voltage level of the reference line 132 and the voltage level of the analog voltage. The comparison of the voltage levels may be performed in the form of a comparison of analog voltages or a comparison of digital values.

[0096] 1, the imaging device 100A further includes a voltage supply circuit 150 and a control circuit 160. The voltage supply circuit 150 is electrically connected to each pixel Px by being connected to, for example, a voltage line 152 connected to the counter electrode. The voltage supply circuit 150 supplies a predetermined voltage to the photoelectric conversion unit of each pixel Px via the voltage line 152 during operation of the imaging device 100A.

[0097] The voltage supply circuit 150 is configured to be able to switch between at least two or more different voltages and apply them to the voltage line 152. The voltage output from the voltage supply circuit 150 may be changed stepwise or continuously. The voltage supply circuit 150 is not limited to a specific power supply circuit, and may be a circuit that converts a voltage supplied from a power source such as a battery into a predetermined voltage, or a circuit that generates a predetermined voltage. The voltage supply circuit 150 may be part of the row scanning circuit 120 described above.

[0098] The control circuit 160 receives, for example, externally provided command data, clocks, and the like, and controls the entire imaging device 100A. The control circuit 160 may be realized, for example, by a microcontroller including one or more processors. The control circuit 160 may include one or more memories. In the configuration illustrated in FIG. 1, the control circuit 160 includes a memory 162 as a part thereof. The memory 162 may be provided in the form of a chip or package separate from the imaging device 100A.

[0099] In this example, an image processing circuit 164 is electrically connected to the control circuit 160. The image processing circuit 164 may be, for example, a DSP (Digital Signal Processor), an ISP (Image Signal Processor), or the like. This can be realized by using FPGAs (field-programmable gate arrays), etc. The image processing circuitry 164 may be part of the control circuitry 160.

[0100] Typically, the control circuit 160 has a timing generator and supplies drive signals to the row scanning circuit 120, the detection circuit 130A, the voltage supply circuit 150, etc. In FIG. 1, the arrows extending toward the control circuit 160 and the arrows extending from the control circuit 160 schematically represent input signals to the control circuit 160 and output signals from the control circuit 160, respectively. In this example, the control circuit 160 is configured to receive from the detection circuit 130A the results of comparing the levels of the output signals from the pixels Px of each column with the voltage level of the reference line 132, and to supply drive signals to the voltage supply circuit 150 according to the comparison results of the voltage levels.

[0101] Based on a drive signal from the control circuit 160, for example, when the level of the output signal detected by the detection circuit 130A is equal to or higher than the voltage level of the reference line 132, the voltage supply circuit 150 applies to the voltage line 152 a voltage such that the potential difference applied between the counter electrode and the pixel electrode of the photoelectric conversion unit is a first potential difference. When the level of the output signal detected by the detection circuit 130A is lower than the voltage level of the reference line 132, the voltage supply circuit 150 applies to the voltage line 152 a voltage such that the potential difference applied between the counter electrode and the pixel electrode is a second potential difference greater than the first potential difference. For example, when the level of the output signal detected by the detection circuit 130A is equal to or higher than the voltage level of the reference line 132, the voltage supply circuit 150 applies to the voltage line 152 a first voltage V1. When the level of the output signal detected by the detection circuit 130A is lower than the voltage level of the reference line 132, the voltage supply circuit 150 applies to the voltage line 152 a second voltage V2 higher than the first voltage V1. Typically, when the illuminance on the photoelectric conversion unit is relatively high, the level of the output signal from the detection circuit 130A becomes equal to or higher than the voltage level of the reference line 132. That is, in this embodiment, the voltage applied to, for example, the counter electrode of the photoelectric conversion unit is changed according to the illuminance on the photoelectric conversion unit, thereby controlling the potential difference applied between the counter electrode of the photoelectric conversion unit and the pixel electrode.

[0102] When the level of the output signal detected by the detection circuit 130A is equal to or higher than the voltage level of the reference line 132, for example, a relatively low first voltage V1 is applied to the voltage line 152. In this configuration, the voltage supplied to the photoelectric conversion unit is dynamically reduced under high-illumination conditions. This reduces power consumption compared to a configuration in which a relatively high voltage of around 10 V is applied to the photoelectric conversion unit regardless of the shooting environment. On the other hand, when the illuminance of the photoelectric conversion unit is relatively low, a relatively high second voltage V2 is applied to the photoelectric conversion unit. As will be described in detail later, the photoelectric conversion unit of the pixel Px may have photoelectric conversion characteristics such that the photoelectric conversion efficiency increases as the bias voltage between the counter electrode and the pixel electrode increases. In this case, the sensitivity of the pixel Px can be increased by applying a relatively high second voltage V2 to the photoelectric conversion unit via the voltage line 152 to increase the potential difference between the counter electrode and the pixel electrode. In other words, the sensitivity of the pixel Px increases in dark environments, enabling high-sensitivity shooting. Thus, according to an embodiment of the present disclosure, the sensitivity is adjusted by electrical control according to the illuminance, thereby achieving the effect of reducing power consumption while enabling photography at a sensitivity that corresponds to the environment at the time of photography.

[0103] The functions of the control circuit 160 described above may be realized by a combination of a general-purpose processing circuit and software, or may be realized by hardware specialized for such processing. In the example shown in FIG. 1, the row scanning circuit 120, the detection circuit 130A, the voltage supply circuit 150, and the control circuit 160 are integrally formed on a semiconductor substrate 110 on which a plurality of pixels Px are arranged. For example, the control circuit 160 may be an integrated circuit formed on the semiconductor substrate 110. By arranging these circuits on the semiconductor substrate 110 on which the output circuits of each pixel Px are formed, it becomes possible to form these circuits integrally on the semiconductor substrate 110 together with the output circuits of each pixel Px by applying a process similar to the process of forming the output circuits of each pixel Px. However, it is not essential that all of these circuits be integrally formed on the semiconductor substrate 110 together with the output circuits of each pixel Px. It is also possible that some or all of these circuits are integrally formed on the semiconductor substrate 110 together with the output circuits of each pixel Px. The pixel Px may be disposed on a substrate different from the semiconductor substrate 110 on which the output circuit of the pixel Px is formed. In this case, the imaging device 100A may be provided in the form of a package in which the semiconductor substrate 110 on which the plurality of pixels Px are formed, the row scanning circuit 120, the detection circuit 130A, the voltage supply circuit 150, and the control circuit 160 are integrated.

[0104] In the above example, the control circuit 160 detects the level of the output signal from each pixel Px using the detection circuit 130A, and determines whether the amount of light incident on the photoelectric conversion unit is equal to or greater than a predetermined amount of light by comparing the detected level with the voltage level of the reference line 132. In other words, the control circuit 160 performs determination using the voltage level of the reference line 132 as a threshold value. However, the method of determining whether the amount of light incident on the photoelectric conversion unit is equal to or greater than a predetermined amount of light is not limited to this example.

[0105] For example, the detection circuit 130A includes an analog-to-digital conversion circuit and outputs a detected output signal line S j The detection circuit 130A may be configured to output digital value data representing the magnitude of the voltage of the pixel electrode 152 to the control circuit 160 or the image processing circuit 164. In this case, a threshold value for determining whether the amount of light incident on the photoelectric conversion unit 152 is equal to or greater than a predetermined value may be stored in advance in, for example, the memory 162. For example, if the digital value received from the detection circuit 130A is equal to or greater than the threshold value stored in the memory 162, the control circuit 160 determines that the amount of light incident on the photoelectric conversion unit 152 is equal to or greater than the predetermined value. Furthermore, the control circuit 160 executes control so that a voltage is applied to the voltage line 152 such that the potential difference between the counter electrode and the pixel electrode 152 becomes a relatively small first potential difference. For example, the control circuit 160 drives the voltage supply circuit 150 so that a relatively low first voltage V1 is applied to the voltage line 152.

[0106] (Example configuration of pixel Px) 2 shows an exemplary circuit configuration of the image pickup device 100 A. In FIG. 2, four pixels Px selected from the plurality of pixels Px included in the image pickup area shown in FIG.

[0107] Each of the pixels Px includes a photoelectric conversion unit 10 and an output circuit 20 electrically connected to the photoelectric conversion unit 10. In the configuration illustrated in Fig. 2, the output circuit 20 includes a signal detection transistor 22, an address transistor 24, and a reset transistor 26. The signal detection transistor 22, the address transistor 24, and the reset transistor 26 are typically field-effect transistors formed on a semiconductor substrate 110, and the following describes an example in which N-channel MOS transistors are used for these transistors.

[0108] As shown schematically in Fig. 2, the photoelectric conversion unit 10 includes a counter electrode 11 as a first electrode, a pixel electrode 12 as a second electrode, and a photoelectric conversion layer 13 sandwiched between the counter electrode 11 and the pixel electrode 12. The counter electrode 11 is light-transmitting. Note that the term "light-transmitting" in this specification means that the photoelectric conversion layer 13 transmits at least a portion of light of a wavelength that can be absorbed, and it is not essential that the photoelectric conversion layer 13 transmits light over the entire wavelength range of visible light.

[0109] As shown in the figure, the counter electrode 11 of each pixel Px is electrically connected to a voltage line 152. Therefore, the voltage supply circuit 150 can selectively apply, for example, a first voltage V1 or a second voltage V2 to the counter electrodes 11 of multiple pixels Px collectively via the voltage line 152. In FIG. 2, the voltage line 152 is illustrated as being connected to each of the counter electrodes 11 of multiple pixels Px. However, typically, the counter electrode 11 of each pixel Px is a single light-transmitting electrode that is continuous between the multiple pixels Px, and the voltage line 152 does not need to be a wiring that branches into multiple lines.

[0110] On the other hand, the pixel electrodes 12 are provided electrically separated for each pixel Px. As shown in the figure, the pixel electrodes 12 of each pixel Px are connected to the gates of the signal detection transistors 22 of the corresponding output circuits 20. The source of the signal detection transistor 22 is connected to the corresponding output signal line S via the address transistor 24. jThe drain of the signal detection transistor 22 is connected to a power supply line 32. When a power supply voltage VDD of about 3.3 V is applied to the power supply line 32 during operation, the power supply line 32 functions as a source follower power supply.

[0111] The gate of the address transistor 24 is connected to the row signal line R i The row scanning circuit 120 is connected to the row signal line R i By controlling the voltage level applied to the address transistor 24, the address transistor 24 is switched on and off, and the pixel Px belonging to the selected row is supplied to the output signal line S j The signal can be read out.

[0112] In this example, the output circuit 20 includes a reset transistor 26. One of the drain and source of the reset transistor 26 is connected to a node FD. The node FD electrically connects the photoelectric conversion unit 10 to the gate of the signal detection transistor 22. The other of the drain and source of the reset transistor 26 is connected to a reset voltage line 36. The reset voltage line 36 supplies a predetermined reset voltage V RST is applied. Typically, as shown in the figure, the reset signal line 46 is commonly connected to the gates of the reset transistors 26 of multiple pixels Px that belong to the same row.

[0113] In this example, the reset signal line 46 is connected to the row scanning circuit 120. The row scanning circuit 120 turns on the reset transistors 26 of the pixels Px in units of rows by controlling the voltage level applied to the reset signal line 46. As a result, the potential of the node FD of the pixel Px whose reset transistor 26 is turned on becomes V RST If the voltage applied to the counter electrode 11 of each pixel Px from the voltage supply circuit 150 is V1 or V2, the bias voltage applied between the pixel electrode 12 and the counter electrode 11 immediately after resetting can be expressed as (V1 - V RST ) or (V2-V RST ) As will be described later, in the embodiment of the present disclosure, (V1 - V RST )>0 and (V2-VRST The specific values ​​of these voltages may be chosen so that .times. ...

[0114] 3A shows an exemplary device structure of a pixel Px. A semiconductor substrate 110 has impurity regions 111 to 115 and an isolation region 116. The isolation region 116 electrically isolates the output circuits 20 provided for each pixel Px between the pixels Px. In the following, a P-type silicon substrate is exemplified as the semiconductor substrate 110. The impurity regions 111 to 115 are typically N-type diffusion regions. The semiconductor substrate 110 may be an insulating substrate having a semiconductor layer provided on its surface.

[0115] The signal detection transistor 22 includes impurity regions 113 and 114 out of the impurity regions 111 to 115, a gate insulating layer 22g on the semiconductor substrate 110, and a gate electrode 22e on the gate insulating layer 22g. The impurity region 113 functions as the drain region of the signal detection transistor 22. The impurity region 114 functions as the source region of the signal detection transistor 22. In the illustrated configuration, the address transistor 24 shares the impurity region 114 with the signal detection transistor 22. The address transistor 24 includes a gate insulating layer 24g on the semiconductor substrate 110, a gate electrode 24e on the gate insulating layer 24g, and an impurity region 115. The impurity region 115 functions as the source region of the address transistor 24.

[0116] The reset transistor 26 includes impurity regions 111 and 112, a gate insulating layer 26g on the semiconductor substrate 110, and a gate electrode 26e on the gate insulating layer 26g. Although not shown in FIG. 3A, the impurity region 112 is connected to the reset voltage line 36. The impurity region 113 serving as the drain region of the signal detection transistor 22 is connected to the power supply line 32. The impurity region 113 serving as the source region of the address transistor 24 is connected to the power supply line 32. In the region 115, the output signal line S j 3A, the element isolation region 116 is also provided between the reset transistor 26 and the signal detection transistor 22.

[0117] The interlayer insulating layer 50 covers the signal detection transistor 22, the address transistor 24, and the reset transistor 26 formed on the semiconductor substrate 110. The photoelectric conversion unit 10 of each pixel Px is supported by the interlayer insulating layer 50. The interlayer insulating layer 50 includes a plurality of insulating layers each made of, for example, silicon dioxide.

[0118] The counter electrode 11 of the photoelectric conversion unit 10 is located on the side where light from a subject is incident, and is made of a transparent conductive material such as ITO. As described above, the counter electrode 11 is typically provided in the form of a single continuous electrode layer spanning multiple pixels Px. An optical filter 14 such as a color filter, a microlens 16, and the like may be arranged on the main surface of the counter electrode 11 opposite the photoelectric conversion layer 13.

[0119] The photoelectric conversion layer 13, located between the counter electrode 11 and the pixel electrode 12, is formed from an organic material or an inorganic material such as amorphous silicon, and generates excitons when light is incident through the counter electrode 11. The photoelectric conversion layer 13 may include a layer made of an organic material and a layer made of an inorganic material. Like the counter electrode 11, the photoelectric conversion layer 13 is typically provided in the form of a single continuous photoelectric conversion structure spanning multiple pixels Px.

[0120] The pixel electrode 12 is located closer to the semiconductor substrate 110 than the photoelectric conversion layer 13, and is spatially separated from the pixel electrodes 12 of other adjacent pixels Px, thereby electrically isolating them. The pixel electrode 12 may be formed from a metal such as aluminum or copper, a metal nitride, or polysilicon that has been doped with impurities to make it conductive.

[0121] Each pixel Px has a conductive structure 52 inside the interlayer insulating layer 50. The conductive structure 52 electrically connects the pixel electrode 12 to the output circuit 20, which includes a signal detection transistor 22 and the like. The conductive structure 52 includes a via formed from a metal such as copper, a plug formed from polysilicon, and the like, and electrically connects the pixel electrode 12 to an impurity region 111 formed in the semiconductor substrate 110, as schematically shown in FIG. 3A. The conductive structure 52 also connects the pixel electrode 12 to the gate electrode 22e of the signal detection transistor 22. That is, the output circuit 20 outputs a signal according to the potential of the pixel electrode 12 to the corresponding output signal line S by a source follower including the signal detection transistor 22. j Output to.

[0122] During operation, a predetermined voltage is applied from the voltage supply circuit 150 to the counter electrode 11 via the voltage line 152, thereby applying a potential difference ΔV between the counter electrode 11 and the pixel electrode 12, as shown schematically in FIG. 3A . Here, the voltage supply circuit 150 applies a voltage to the counter electrode 11 such that the potential of the counter electrode 11 is higher than the potential of the pixel electrode 12, with the pixel electrode 12 being used as a reference. By making the potential of the counter electrode 11 higher than the potential of the pixel electrode 12, positive charges, such as holes, among the positive and negative charges generated in the photoelectric conversion layer 13 by incident light can be collected by the pixel electrode 12 as signal charges. Below, unless otherwise noted, an example will be described in which holes are used as signal charges. In the example shown in FIG. 3A , an electron blocking layer 13e is disposed between the photoelectric conversion layer 13 and the pixel electrode 12 to suppress electron injection from the photoelectric conversion layer 13 to the pixel electrode 12. The electron blocking layer 13e may have a photoelectric conversion function.

[0123] In a typical embodiment of the present disclosure, in both a state where the first voltage V1 is applied to the voltage line 152 from the voltage supply circuit 150 and a state where the second voltage V2 is applied to the voltage line 152 from the voltage supply circuit 150, the potential of the counter electrode 11 is higher than the potential of the pixel electrode 12. The potential of the pixel electrode 12 is the reset voltage V1 supplied via the reset transistor 26. RST Therefore, in an exemplary embodiment of the present disclosure, (V1 - V RST )>0 and (V2-V RST )>0. Reset voltage V RST For example, a positive voltage of 0V or close to 0V is used as the voltage.

[0124] The impurity region 111 is connected to the conductive structure 52 in the interlayer insulating layer 50. The PN junction formed in the semiconductor substrate 110 by the impurity region 111 functions as a charge storage capacitor that temporarily stores positive charges, for example, holes, collected by the pixel electrode 12. In a typical embodiment of the present disclosure, holes are used as signal charges, and therefore, as signal charges are accumulated in the impurity region 111, the potential of the impurity region 111 as a charge storage section rises.

[0125] Of course, it is also possible to use electrons, for example, as signal charges, by applying a voltage to the counter electrode 11 that makes the potential of the counter electrode 11 lower than that of the pixel electrode 12. FIG. 3B is a schematic cross-sectional view illustrating the operation of the pixel Px when electrons are used as signal charges. When collecting negative charges using the pixel electrode 12, for example, a voltage may be applied to the counter electrode 11 that makes the potential of the pixel electrode 12 higher than that of the counter electrode 11. In the configuration illustrated in FIG. 3B, a hole-blocking layer 13h is disposed between the photoelectric conversion layer 13 and the pixel electrode 12, thereby suppressing the injection of holes from the photoelectric conversion layer 13 to the pixel electrode 12.

[0126] In this case as well, when the level of the output signal detected by the detection circuit 130A is equal to or higher than the voltage level of the reference line 132, the control circuit 160 controls the voltage supply circuit 150 to output a predetermined voltage so that the potential difference applied between the counter electrode 11 and the pixel electrode 12 becomes a first potential difference. When the level of the output signal detected by the detection circuit 130A is lower than the voltage level of the reference line 132, the control circuit 160 controls the voltage supply circuit 150 to output a voltage so that the potential difference applied between the counter electrode 11 and the pixel electrode 12 becomes a second potential difference that is larger than the first potential difference. In a configuration in which electrons are accumulated as signal charge, the potential of the impurity region 111 serving as a charge accumulation portion decreases as signal charge accumulates in the impurity region 111.

[0127] (Example photoelectric conversion characteristics of the photoelectric conversion layer) Here, a description will be given of the relationship between the photoelectric conversion characteristics of the photoelectric conversion layer 13 and the voltage supplied by the voltage supply circuit 150 to the voltage line 152. Unless otherwise specified, the following describes an example in which holes are used as signal charges.

[0128] Fig. 4 shows a typical example of the photoelectric conversion characteristics of the photoelectric conversion layer 13. In Fig. 4, the horizontal axis represents the potential difference ΔV applied between the counter electrode 11 and the pixel electrode 12, and the vertical axis represents the photoelectric conversion efficiency η of the photoelectric conversion layer 13. Here, the photoelectric conversion efficiency η means the ratio per unit second of the number of charges collected by the pixel electrode 12 to the number of photons incident on the photoelectric conversion unit 10 for one pixel Px. The number of charges is measured in units of elementary electric charge.

[0129] 4, in the embodiment of the present disclosure, the photoelectric conversion efficiency η in the photoelectric conversion layer 13 generally changes in an upwardly convex curve with an increase in the potential difference ΔV applied between the counter electrode 11 and the pixel electrode 12. A photoelectric conversion layer having the photoelectric conversion characteristics shown in FIG. 4 can be realized by using organic photoelectric conversion materials or combinations thereof that are generally applied to the formation of organic photoelectric conversion films.

[0130] In the example shown in FIG. 4, the photoelectric conversion efficiency η shows a relatively steep increase with respect to the change in the potential difference ΔV in a relatively low voltage region where the potential difference ΔV is about 0 to 3 V. It shows a relatively gradual increase with respect to the change in the potential difference ΔV in a relatively high voltage region of 3 V or more. In this specification, the voltage range in which the photoelectric conversion efficiency η shows a relatively steep increase with respect to the change in the potential difference ΔV applied between the counter electrode 11 and the pixel electrode 12 is called the first voltage range, and the voltage range in which the photoelectric conversion efficiency η shows a relatively gradual increase with respect to the change in the potential difference ΔV is called the second voltage range.

[0131] The first voltage range can be defined as a voltage range in which the potential difference ΔV applied between the counter electrode 11 and the pixel electrode 12, in other words, the rate of change in the photoelectric conversion efficiency of the photoelectric conversion unit 10 with respect to the bias voltage, is greater than when the bias voltage is in the second voltage range. The specific ranges of the first and second voltage ranges may vary depending on the application of the imaging device 100A, the material of the photoelectric conversion layer 13, and other factors, but can be defined, for example, as follows: In a graph of the photoelectric conversion efficiency η of the photoelectric conversion unit 10 with respect to the bias voltage between the counter electrode 11 and the pixel electrode 12, a tangent line T1 is drawn at the point where the photoelectric conversion efficiency η rises from 0, as shown by the dashed line in FIG. 4 . A tangent line T2 is also drawn at the point corresponding to the maximum bias voltage during operation. The bias voltage value at the intersection of these tangent lines T1 and T2 is defined as Vt, and the voltage range below Vt is defined as the first voltage range.

[0132] In the example shown in Fig. 4, the value of the potential difference ΔV at which the photoelectric conversion efficiency η rises from 0 is 0 V, and the maximum value of the bias voltage during operation is ΔV = 12 V. The X coordinate of the intersection of the tangent lines at these points is approximately 3 V. Therefore, as shown in Fig. 4, the voltage range from approximately 0 V to less than 3 V can be defined as the first voltage range, and the voltage range from approximately 3 V to 12 V can be defined as the second voltage range.

[0133] However, as shown in Fig. 5, when a characteristic curve is obtained in which the photoelectric conversion efficiency η rises gradually from 0 in a region where the potential difference ΔV is relatively small, the tangent line T1 at the point where the photoelectric conversion efficiency η rises from 0 and the tangent line T2 at the point where the bias voltage is at its maximum during operation may not intersect. In such a case, a tangent line T3 is drawn at point R where the photoelectric conversion efficiency η is 0.06, as shown by the dashed line in Fig. 5, in the graph of the photoelectric conversion efficiency η, and the intersection of this tangent line T3 and the tangent line T2 is determined. The bias voltage value at the intersection of the tangent line T3 and the tangent line T2 may then be defined as Vt, and a voltage range less than Vt may be defined as the first voltage range.

[0134] The photoelectric conversion efficiency η of 0.06 mentioned above is a normalized value when the photoelectric conversion efficiency η at the point corresponding to the maximum bias voltage during operation is set to 1. In the field of digital cameras, ND filters are sometimes combined with digital cameras for shooting at slow shutter speeds. The sensitivity achieved with a photoelectric conversion efficiency η of 0.06 roughly corresponds to that achieved with an ND16 filter. Therefore, by calculating Vt using the tangent at point R, where the Y coordinate is 0.06 on a graph of photoelectric conversion efficiency η versus potential difference ΔV, it is possible to achieve sensitivity equivalent to a range from ND2 to ND16, for example, through electrical control.

[0135] Alternatively, the second voltage range may be defined as a voltage range in which the change in photoelectric conversion efficiency η per 1 V change in bias voltage is less than 10%. In this case, the second voltage range is defined as a voltage range in which, when a first point P(a, b) and a second point Q(a+1, c) are taken on the graph as shown in Figure 6, the increment (cb) in photoelectric conversion efficiency η satisfies the relationship (cb)<0.1*b. Here, "*" in the above relational expression represents multiplication.

[0136] Alternatively, the first voltage range or the second voltage range can be determined as follows: For example, the photoelectric conversion voltage of the photoelectric conversion unit 10 relative to the bias voltage between the counter electrode 11 and the pixel electrode 12 is In the graph of the photoelectric conversion efficiency η, as shown in Fig. 7, the region where the photoelectric conversion efficiency η is 0.7 or higher may be defined as the second voltage range. Note that defining the region where the photoelectric conversion efficiency η is 0.7 or higher as the second voltage range has the advantage of making it easier to associate it with the ISO value. The specific ranges of the first voltage range and the second voltage range may be set appropriately depending on the application of the image capture device 100A, etc.

[0137] In a typical embodiment of the present disclosure, the first voltage V1 and the second voltage V2 are set so that the photoelectric conversion efficiency η when the first voltage V1 is supplied to the photoelectric conversion unit 10 is lower than when the second voltage V2 is supplied to the photoelectric conversion unit 10. As described above, the photoelectric conversion efficiency η in the photoelectric conversion layer 13 typically increases substantially monotonically with an increase in the potential difference ΔV applied between the counter electrode 11 and the pixel electrode 12. Therefore, for example, a voltage within a first voltage range can be used as the first voltage V1, and a voltage within a second voltage range can be used as the second voltage V2. Hereinafter, an example of the operation of the imaging device 100A when a voltage within the first voltage range is used as the first voltage V1 and a voltage within the second voltage range is used as the second voltage V2 will be described.

[0138] (First Operation Example of Imaging Device 100A) 4 with an increase in the potential difference ΔV applied between the counter electrode 11 and the pixel electrode 12, and the bias voltage value Vt at the intersection of the tangent lines T1 and T2 is 3 V. In this case, for example, if a voltage range less than 3 V is defined as a first voltage range and a voltage range equal to or greater than 3 V and equal to or less than 12 V is defined as a second voltage range, then, for example, a voltage of 2 V can be used as the first voltage V1 and a voltage of 6 V can be used as the second voltage V2.

[0139] When these definitions are adopted for the first voltage range and the second voltage range, the ratio of the photoelectric conversion efficiency η when the second voltage V2 is applied to the counter electrode 11 to the photoelectric conversion efficiency η when the first voltage V1 is applied to the counter electrode 11 is typically 1.25 or more and 100 or less. In this example, the photoelectric conversion efficiency η when the first voltage V1 is applied to the counter electrode 11 is approximately 0.55, and the photoelectric conversion efficiency η when the second voltage V2 is applied is approximately 0.87, so the ratio of these η values ​​is approximately 1.58. Note that the ratio (V2 / V1) of the second voltage V2 to the first voltage V1, 3, is greater than the above-mentioned ratio value 1.58 for η.

[0140] 8 is a schematic flowchart showing a first exemplary operation of the imaging device 100A. In the example shown in FIG. 8, first, it is determined whether or not the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than a predetermined amount of light (step S1). For example, j The detection circuit 130A detects the level of the signal output to the pixel PX. If the detected level is equal to or higher than the voltage level of the reference line 132 serving as a threshold, it can be determined that the amount of light incident on the photoelectric conversion unit 10 is equal to or higher than a predetermined amount of light. The detection of the level of the signal from the output circuit 20 may be performed, for example, by turning on the address transistors 24 of some of the pixels Px when the user half-presses the release button, causing the output circuit 20 to output a voltage corresponding to the illuminance. Alternatively, the level of the signal detected by the detection circuit 130A in, for example, the frame immediately preceding the frame from which an image is to be acquired may be used.

[0141] Of course, the method for determining whether the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than the predetermined amount of light is not limited to a specific method, and various methods can be adopted. For example, the level of the signal detected by the detection circuit 130A may be converted into a digital value by an analog-to-digital conversion circuit, and then compared with a threshold value stored in advance in the memory 162 to determine whether the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than the predetermined amount of light. The determination of whether the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than a predetermined amount may be performed by, for example, the control circuit 160 or the image processing circuit 164. The control circuit 160 may include a logic circuit formed on the semiconductor substrate 110. The determination of whether the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than a predetermined amount may be performed by, for example, an ISP arranged outside the imaging device 100A.

[0142] If it is determined that the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than a predetermined amount of light, a voltage is applied to the photoelectric conversion unit 10 so that the potential difference between the counter electrode 11 and the pixel electrode 12 becomes a first potential difference (step S2). The control circuit 160 supplies a drive signal to the voltage supply circuit 150, causing the voltage supply circuit 150 to apply, for example, a first voltage V1 to the voltage line 152. As shown in FIG. 4, when the first voltage V1 is applied to the counter electrode 11, the photoelectric conversion efficiency of the photoelectric conversion unit 10 is relatively low, and therefore, each pixel Px of the imaging device 100A is in a state where the sensitivity is relatively reduced. As described above, when the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than a predetermined amount of light, this corresponds to a case where the illuminance on the photoelectric conversion unit 10 is high. That is, in this example, when the illuminance on the photoelectric conversion unit 10 is high, the sensitivity of the pixel Px is automatically reduced. In other words, it can be said that a state as if an ND filter were mechanically inserted is realized by electrical control. Therefore, the user of the imaging device 100A can more easily capture images that are suited to the environment.

[0143] In this way, by controlling the voltage applied from the voltage supply circuit 150 to the photoelectric conversion unit 10, it is possible to realize an ND filter function through electrical control. Therefore, even in shooting scenes where it was previously necessary to select an appropriate one from multiple ND filters, there is no longer a need to prepare multiple ND filters in advance, resulting in the effect of simplifying the shooting equipment. According to the embodiment of the present disclosure, continuous change in sensitivity, i.e., stepless control, which was not possible with conventional silicon image sensors, is also possible, thereby increasing the degree of freedom in shooting according to the scene.

[0144] 9 and 10 are schematic cross-sectional views for explaining the change in photoelectric conversion efficiency η with respect to the change in illuminance when a voltage of 2 V is applied to the counter electrode 11 as the first voltage V1. During operation, a potential difference ΔV is applied between the counter electrode 11 and the pixel electrode 12. The reset voltage V RST is a voltage near 0V, for example, and therefore, when the voltage supply circuit 150 is supplying the first voltage V1, a potential difference of approximately 2V is applied to the photoelectric conversion layer 13, as shown schematically in FIG. 9.

[0145] When light is incident on the photoelectric conversion layer 13 and charges are generated inside the photoelectric conversion layer 13, these charges move according to the electric field between the counter electrode 11 and the pixel electrode 12. As shown schematically in Fig. 9, positive charges are accumulated in the impurity region 111, which serves as a charge accumulation section, via the conductive structure 52, and negative charges are discharged from the photoelectric conversion layer 13 to the voltage line 152 via the counter electrode 11.

[0146] When the first voltage V1 is supplied from the voltage supply circuit 150, in other words, when the potential difference ΔV between the counter electrode 11 and the pixel electrode 12 is relatively small, the number of charge pairs generated by photoelectric conversion is small, and the probability that positive charges will recombine before reaching the pixel electrode 12 is high. Furthermore, it becomes difficult for positive charges to overcome the potential barrier formed by the electron blocking layer 13e. Therefore, when compared at the same illuminance, less signal charge accumulates in the impurity region 111 than when a relatively large potential difference ΔV is applied between the counter electrode 11 and the pixel electrode 12. In other words, the sensitivity of the pixel Px is reduced.

[0147] As the signal charge continues to accumulate in the impurity region 111, the potential of the impurity region 111 gradually increases because positive charges are used as the signal charge. The effective bias voltage applied to pixel Px is smaller than the actual value of the first voltage V1, and the more signal charge is accumulated in the impurity region 111, the lower the effective bias voltage becomes. In other words, as the signal charge is accumulated in the impurity region 111, the sensitivity of pixel Px decreases.

[0148] As shown by the arrow hν in FIG. 10 , assume that the illuminance of the photoelectric conversion unit 10 increases while the voltage supply circuit 150 supplies the first voltage V1. As the illuminance increases, the signal charge accumulated in the impurity region 111 increases, causing the potential of the impurity region 111 to rise, thereby reducing the effective bias voltage applied to the photoelectric conversion layer 13. For example, if the bias voltage decreases from 2 V to approximately 1 V, as can be seen from FIG. 4 , the photoelectric conversion efficiency η decreases from 0.55 to approximately 0.28, resulting in a further decrease in the sensitivity of the pixel Px. In other words, while the voltage applied to the voltage line 152 from the voltage supply circuit 150 is kept constant, the effective bias voltage applied to the photoelectric conversion layer 13 is changed according to the illuminance, resulting in an expanded dynamic range. The state in which the voltage supply circuit 150 supplies the first voltage V1 within the first voltage range may be referred to as a sensitivity variable mode.

[0149] FIG. 11 shows a typical example of the change in the signal level from the output circuit 20 in response to a change in the amount of light incident on the photoelectric conversion unit 10. It can be seen from FIG. 11 that in areas where the amount of light is relatively low, the signal level changes linearly with the change in the amount of light, ensuring linearity. As the amount of light increases further, the rate of increase in the signal level relative to the increase in the amount of light slows down, and the graph showing the change in the signal level relative to the change in the amount of light becomes curved. In this way, the signal level automatically decreases with increasing light amount, thereby expanding the dynamic range in the direction of higher illuminance. Utilizing this, the dynamic range in the direction of higher illuminance can be expanded, for example, by about twice as much as when the signal level changes linearly with increasing light amount.

[0150] In areas with higher illuminance, the deviation from a straight line of the graph showing the change in signal level relative to the change in light intensity becomes larger. This is because the smaller the potential difference ΔV, the more likely it is that the effects of a decrease in the charge pairs generated by photoelectric conversion and an increase in the annihilation of charge pairs due to recombination become apparent.

[0151] However, by obtaining a characteristic curve such as that shown in FIG. 11 in advance, it becomes possible to apply appropriate correction to the signal level detected by the detection circuit 130A. For example, correction coefficients corresponding to the amount of light may be stored in advance in the memory 162, for example in the form of a table, and the pixel value of each pixel Px may be determined by multiplying the pixel value by the correction coefficient. This correction compensates for linearity and makes it possible to further expand the dynamic range in the direction of high illuminance. For example, compared to when the signal level changes linearly with increasing light amount, the dynamic range in the direction of high illuminance can be expanded approximately three times.

[0152] Correction to the level of the detected signal may be performed by the image processing circuit 164. Similar to the above-described control circuit 160, the function of the image processing circuit 164 may be realized by a combination of a general-purpose processing circuit and software, or by hardware specialized for image processing. Correction to the level of the detected signal may be performed by the control circuit 160.

[0153] Referring again to FIG. 8, if it is determined in step S1 that the amount of light incident on the photoelectric conversion unit 10 is less than the predetermined amount of light, a voltage is applied to the photoelectric conversion unit 10 so that the potential difference between the counter electrode 11 and the pixel electrode 12 becomes a second potential difference that is larger than the first potential difference (step S3). The control circuit 160 supplies a drive signal to the voltage supply circuit 150, and, for example, A second voltage V2 higher than the voltage V1 is applied to the voltage line 152 from the voltage supply circuit 150.

[0154] When the potential difference ΔV between the counter electrode 11 and the pixel electrode 12 increases, the electric field inside the photoelectric conversion layer 13 increases, and as shown schematically in FIG. 12, more positive charges are collected by the pixel electrode 12. That is, the sensitivity of the pixel Px when the second voltage V2 is applied to the counter electrode 11 is higher than when the first voltage V1 is applied to the counter electrode 11. Here, a voltage of 6 V is used as the second voltage V2. As can be seen from FIG. 4, the photoelectric conversion efficiency when the second voltage V2 is applied to the counter electrode 11 is higher than when the first voltage V1 is applied to the counter electrode 11. In the example shown in FIG. 4, the value of the photoelectric conversion efficiency η at this time is approximately 0.87.

[0155] The potential of the impurity region 111 gradually increases as signal charges continue to accumulate in the impurity region 111, just as when the first voltage V1 is applied to the counter electrode 11. Therefore, the effective bias voltage applied to the photoelectric conversion layer 13 is smaller than the value of the second voltage V2, and can be, for example, about 5 V. Note that if the potential of the pixel electrode 12 exceeds the potential of the counter electrode 11, the pixel electrode 12 will no longer collect positive charges, so the potential of the impurity region 111 will basically never exceed the value of the second voltage V2.

[0156] FIG. 13 schematically shows a typical example of a change in the level of the signal from the output circuit 20 in response to a change in the amount of light incident on the photoelectric conversion unit 10 when a second voltage V2 is applied to the counter electrode 11. FIG. 13 also shows a change in the level of the output signal in response to a change in the amount of light when a first voltage V1 of 2 V is applied to the counter electrode 11. Graph G1 in FIG. 13 is the same as the graph shown in FIG. 11 and shows a change in the level of the output signal when 2 V is applied to the counter electrode 11. On the other hand, graph G2 in FIG. 13 shows a change in the level of the output signal when 6 V is applied to the counter electrode 11.

[0157] 13, when a relatively high voltage of, for example, 6 V is applied to the counter electrode 11 as the second voltage V2, the level of the signal from the output circuit 20 changes linearly with respect to the change in the amount of light incident on the photoelectric conversion unit 10. That is, in this example, in a low-illuminance environment where the second voltage V2 is supplied from the voltage supply circuit 150, it can be seen that the linearity of the signal output with respect to changes in illuminance is naturally ensured.

[0158] In this manner, the photoelectric conversion unit 10 is supplied with a first voltage V1 within the first voltage range in a relatively high illuminance environment, and with a second voltage V2 within the second voltage range in a relatively low illuminance environment. This control allows the sensitivity to be dynamically adjusted in response to changes in illuminance. For example, in a standard setting, the second voltage V2 within the second voltage range is used as the voltage supplied to the photoelectric conversion unit 10, and in a relatively high illuminance environment, the first voltage V1 within the first voltage range is used as the voltage supplied to the photoelectric conversion unit 10. This allows the sensitivity to be automatically reduced. Furthermore, when the illuminance is relatively high and the first voltage V1 within the first voltage range is supplied to the photoelectric conversion unit 10, as the illuminance further increases, the potential difference ΔV decreases as holes accumulate in the impurity region 111. As a result, the photoelectric conversion efficiency η decreases, thereby further expanding the dynamic range in the direction of higher illuminance.

[0159] 14, a third electrode 15 may be disposed between two adjacent pixel electrodes 12. As will be described below, by controlling the potential of the third electrode 15, it is possible to further expand the dynamic range in the direction of high illuminance.

[0160] 14 shows two pixels Px1 and Px2 adjacent to each other along a row or a column of the plurality of pixels Px. Also, in FIG. 14, the third electrode 15 is The third electrode 15 is disposed between the pixel electrode 12 of pixel Px1 and the pixel electrode 12 of pixel Px2, and in the same layer as these pixel electrodes 12. The third electrode 15 is spatially separated from the pixel electrode 12 of pixel Px1 and the pixel electrode 12 of pixel Px2, and is thereby electrically separated from these pixel electrodes 12. The third electrode 15 is configured to be connected to a power supply (not shown) so that a predetermined voltage can be applied thereto during operation of the imaging device 100A.

[0161] FIG. 15 shows an example of the positional relationship between the pixel electrodes 12 and the third electrodes 15 when viewed from the counter electrode 11 side. In this example, a rectangular third electrode 15 surrounding the pixel electrode 12 is provided in each of the pixels Px1 and Px2. Note that it is not essential to arrange the third electrodes 15 separately for each pixel Px. For example, a single third electrode 15 spanning multiple pixels Px may be provided for each row of multiple pixels Px. Alternatively, a grid-like third electrode 15 may be arranged across multiple pixels Px.

[0162] When a potential lower than that of the counter electrode 11 is applied, the pixel electrode 12 collects positive charges in a region R1 of the photoelectric conversion layer 13 that is located approximately directly above the pixel electrode 12, as shown schematically by the hatched area in Fig. 15. Similarly, when a potential lower than that of the counter electrode 11 is applied to the third electrode 15, the pixel electrode 12 can collect positive charges in a region R2 of the photoelectric conversion layer 13 that is located approximately directly above the third electrode 15.

[0163] Therefore, when the illuminance is high, the third electrode 15 is applied with a reset voltage V RSTBy applying a voltage below ΔV to a portion of the photoelectric conversion layer 13 located between the counter electrode 11 and the third electrode 15, a potential difference of at least ΔV can be applied, as schematically shown in FIG. 16, to enable the third electrode 15 to preferentially collect charges generated near the boundary of the pixel Px. As a result, the number of charges reaching the pixel electrode 12 decreases, further reducing the effective photoelectric conversion efficiency. In other words, it is possible to further expand the dynamic range in the direction of higher illuminance. Furthermore, in a configuration in which a color filter is disposed on each pixel Px, the effect of suppressing color mixing can also be achieved. The voltage applied to the third electrode 15 may be supplied from a voltage supply circuit 150.

[0164] (Second Operation Example of Imaging Device 100A) Next, a second example of the operation of the imaging device 100A will be described. In the first example described above, a voltage selected from the first voltage range is used as the first voltage V1, and a voltage selected from the second voltage range is used as the second voltage V2. However, this is not limiting, and for example, both the first voltage V1 and the second voltage V2 may be voltages selected from the second voltage range.

[0165] As shown in Fig. 4, the change in signal level in the second voltage range with respect to a change in the amount of light incident on the photoelectric conversion unit 10 is relatively small compared to the first voltage range, and in the example shown in Fig. 4, it can be said that the photoelectric conversion unit 10 exhibits relatively flat photoelectric conversion characteristics in the second voltage range. The second voltage range may be, for example, a voltage range in which the change in signal level with respect to a change in the amount of light incident on the photoelectric conversion unit 10 is within 25%. "Within 25% of the change in signal level with respect to a change in the amount of incident light" means, in ISO terms, a change equivalent to (1 / 3) the difference between two adjacent levels.

[0166] By selecting specific values ​​of the first voltage V1 and the second voltage V2 from voltages within the second voltage range, it becomes possible to capture images with sensitivity according to the illuminance while maintaining linearity. For example, a voltage of 6 V can be used as the first voltage V1, and a voltage of 12 V can be used as the second voltage V2. In the example shown in FIG. 4, the photoelectric conversion efficiency η when the first voltage V1 is applied to the counter electrode 11 is approximately 0.87, and the photoelectric conversion efficiency η when the second voltage V2 is applied is approximately 1.0. The ratio of these η values ​​is approximately 1.15. ... In selected cases, the ratio of the photoelectric conversion efficiency η when the second voltage V2 is applied to the counter electrode 11 to the value of the photoelectric conversion efficiency η when the first voltage V1 is applied to the counter electrode 11 can be greater than 1 and not greater than 1.25.

[0167] FIG. 17 schematically shows a typical example of changes in the level of the signal from the output circuit 20 in response to changes in the amount of light incident on the photoelectric conversion unit 10 when a first voltage V1 is applied to the counter electrode 11 and when a second voltage V2 is applied to the counter electrode 11. Graph G2 in FIG. 17 shows changes in the level of the output signal when a voltage of 6 V is applied to the counter electrode 11 as the first voltage V1, and is the same as graph G2 shown in FIG. 13. Graph G3 in FIG. 17 shows changes in the level of the output signal when a voltage of 12 V is applied to the counter electrode 11 as the second voltage V2. Also shown in FIG. 17 is dashed line graph G1, which shows changes in the level of the output signal in response to changes in the amount of light when a voltage of 2 V is applied to the counter electrode 11.

[0168] 17, in both a state where a voltage of 6 V is applied to the counter electrode 11 as the first voltage V1 and a state where a relatively high voltage of 12 V is applied to the counter electrode 11 as the second voltage V2, the level of the signal from the output circuit 20 shows a linear change with respect to the change in the amount of light incident on the photoelectric conversion unit 10. In other words, it can be seen that linearity of the signal output with respect to changes in illuminance can be ensured regardless of whether the first voltage V1 or the second voltage V2 is supplied from the voltage supply circuit 150.

[0169] The example described here is the same as the first example in that a first voltage V1 is used as the voltage applied to the voltage line 152 under standard settings. The operation flow in the second example may also be the same as the flow described with reference to Fig. 8. That is, first, a determination is made as to whether the amount of light incident on the photoelectric conversion unit 10 is a predetermined amount, and if the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than the predetermined amount, in other words, high illuminance, the voltage supply circuit 150 applies a first voltage V1 to the photoelectric conversion unit 10. If the amount of light incident on the photoelectric conversion unit 10 is less than the predetermined amount, in other words, low illuminance, the voltage supply circuit 150 applies a second voltage V2 to the photoelectric conversion unit 10.

[0170] FIG. 18 is a schematic cross-sectional view illustrating the operation of pixel Px under high illuminance. When the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than a predetermined amount, a first voltage V1 is applied to the counter electrode 11. Here, a medium voltage of 6 V is applied to the counter electrode 11. As already explained, as exposure increases, the number of holes accumulated in the impurity region 111 serving as a charge storage unit increases, gradually increasing the potential of the impurity region 111. Therefore, the effective bias voltage applied to the photoelectric conversion layer 13 is smaller than the value of the first voltage V1 and can be, for example, approximately 5 V. In other words, the potential of the impurity region 111 generally does not exceed the voltage of 6 V used as the first voltage V1. Therefore, high-voltage elements and element isolation regions are not required, ensuring high reliability.

[0171] FIG. 19 is a schematic cross-sectional view illustrating the operation of pixel Px under low illumination. When the amount of light incident on the photoelectric conversion unit 10 is less than a predetermined amount, a relatively high second voltage V2 is applied to the counter electrode 11. In this example, a voltage of 12 V is applied to the counter electrode 11. As can be seen from FIG. 4, the photoelectric conversion efficiency η at this time is higher than when the first voltage V1 is applied to the counter electrode 11. In other words, the sensitivity of pixel Px is higher than when the first voltage V1 is applied to the counter electrode 11. This is therefore suitable for imaging under low illumination. A state in which the relatively high second voltage V2 of the first voltage V1 and second voltage V2 within the second voltage range is supplied from the voltage supply circuit 150 may be referred to as a high-sensitivity mode.

[0172] As described above, the potential of the impurity region 111 gradually increases with exposure, and the photoelectric conversion layer 1 The effective bias voltage applied to the photoelectric conversion layer 13 is smaller than the value of the second voltage V2. Therefore, the effective bias voltage applied to the photoelectric conversion layer 13 can be, for example, approximately 11 V. As in the case of high illuminance, the potential of the impurity region 111 does not generally exceed the second voltage V2. That is, even if the potential difference ΔV between the counter electrode 11 and the pixel electrode 12 is relatively large, the increase in the electric field applied to the impurity region 111 can be suppressed. Furthermore, since the illuminance is low to begin with, the increase in the potential of the impurity region 111 due to the accumulation of charge is relatively small, and an extremely high breakdown voltage is not required for the PN junction formed between the impurity region 111 and the region outside it, the gate insulating layer 22g of the signal detection transistor 22, etc. Therefore, reliability is easily ensured.

[0173] In this second example, a relatively low first voltage V1 is applied to the voltage line 152 under standard settings, thereby reducing power consumption during normal shooting. Note that using a relatively low first voltage V1 under standard settings is advantageous not only for power saving but also for faster operation compared to using the second voltage V2 under standard settings. This point will be explained below.

[0174] For example, Japanese Patent No. 6202512 discloses a technology for achieving a global shutter by reducing the potential difference applied between the counter electrode and pixel electrode sandwiching the photoelectric conversion layer to nearly 0 V, thereby reducing pixel sensitivity to essentially zero. When applying this technology, if the difference between the voltage applied to the counter electrode during exposure and the voltage applied to the counter electrode when the pixel sensitivity is reduced to zero and the shutter is electronically closed is large, the time required for voltage switching increases. In contrast, if the difference between the voltages applied to the counter electrode during exposure and shuttering is small, the time required for voltage switching is shortened, enabling faster shutter operation. Furthermore, the driving method described in the second example above is particularly advantageous for applying an electrical global shutter, since it shortens the time required from the end of exposure (i.e., from the time the voltage applied to the counter electrode is reduced to nearly 0 V) ​​to the time the signal is read out. The entire disclosure of Japanese Patent No. 6202512 is incorporated herein by reference.

[0175] (Variation) Fig. 20A shows an exemplary circuit configuration of an image pickup device according to a modification of the first embodiment. Compared to the configuration of the image pickup device 100A described with reference to Fig. 1, the image pickup device 100B shown in Fig. 20A has a detection circuit 130B instead of the detection circuit 130A. The detection circuit 130B does not have the comparator 134.

[0176] The detection circuit 130B includes, for example, an analog-to-digital conversion circuit, and outputs the detected signal S jThe control circuit 160 outputs digital data representing the magnitude of the voltage of the detection circuit 130B to the control circuit 160. Based on the input from the detection circuit 130B, the control circuit 160 determines whether the level of the signal output from the output circuit 20 of each pixel Px is equal to or greater than a predetermined level. A threshold value serving as a basis for the determination may be stored in advance in, for example, the memory 162. For example, if the digital value received from the detection circuit 130B is equal to or greater than the threshold value stored in the memory 162, the control circuit 160 determines that the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than the predetermined amount of light, and drives the voltage supply circuit 150 to apply a relatively low first voltage V1 to the voltage line 152. This configuration makes it possible to reduce the area occupied by the detection circuit 130B on the semiconductor substrate 110 compared to when the comparator 134 is disposed within the detection circuit. Note that the determination of whether the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than the predetermined amount of light may be performed by the image processing circuit 164.

[0177] In each of the above examples, the voltage applied to the counter electrode 11 of the photoelectric conversion unit 10 is switched between the first voltage V1 and the second voltage V2 depending on the illuminance. However, the voltage to be applied is not limited to the counter electrode 11, and as will be described below, the voltage applied to the pixel electrode 12 may also be switched. The voltage applied may be switched between two voltages.

[0178] 20B shows an exemplary circuit configuration of an imaging device according to another modification of the first embodiment. The main difference between the circuit configuration of the imaging device 100C shown in FIG. 20B and the circuit configuration of the imaging device 100A described with reference to FIG. 2 is that in the imaging device 100C, a voltage supply circuit 150 that supplies a first voltage V1 and a second voltage V2 is connected to a reset voltage line 36. That is, in this example, the reset voltage V RSTAt least two mutually different voltages are selectively supplied to the reset voltage line 36 as a reset voltage. In the configuration illustrated in FIG. 20B , a second voltage supply circuit 154 is connected to the voltage line 152. The second voltage supply circuit 154 basically supplies a constant voltage to the voltage line 152 during exposure. The voltage supply circuit 154 may be a separate component independent of the voltage supply circuit 150, or the voltage supply circuits 150 and 154 may each be part of a single voltage supply circuit.

[0179] 20B, the control circuit 160 determines whether the illuminance on the photoelectric conversion unit 10 is equal to or greater than a predetermined illuminance, for example, before the start of a frame in which an image is to be acquired, based on the level of the output signal detected by the detection circuit 130A. If the illuminance on the photoelectric conversion unit 10 is less than the predetermined illuminance, for example, the control circuit 160 sets the first voltage V1, which is relatively lower of the first voltage V1 and the second voltage V2, as the reset voltage V RST The voltage supply circuit 150 is driven so that the first voltage V1 is applied to the reset voltage line 36. Each pixel Px resets the photoelectric conversion unit 10, in other words, resets the potentials of the pixel electrode 12 and the impurity region 111 serving as a charge accumulation unit, based on the first voltage V1.

[0180] Here, the voltage supply circuit 150 supplies a voltage of, for example, 1 V as the first voltage V1 to the reset voltage line 36. Therefore, the potential of the pixel electrode 12 of each pixel Px after the reset is performed is 1 V. At this time, the voltage supply circuit 154 applies a voltage of, for example, 6 V to the counter electrode 11 of each pixel Px via the voltage line 152. That is, the potential difference ΔV between the counter electrode 11 and the pixel electrode 12 at this time is 5 V.

[0181] On the other hand, when the illuminance on the photoelectric conversion unit 10 is equal to or higher than a predetermined illuminance, that is, in a high-illuminance environment, a relatively high second voltage V2 is supplied from the voltage supply circuit 150 to the reset voltage line 36. For example, when a voltage of 4 V is used as the second voltage V2, the potential difference ΔV between the counter electrode 11 and the pixel electrode 12 is reduced to 2 V compared to when the first voltage V1 is applied to the reset voltage line 36. In other words, it becomes possible to capture images with lower sensitivity.

[0182] In this example, it is not essential to use a voltage in the first voltage range as the first voltage V1 and a voltage in the second voltage range as the second voltage V2. As in the second example described above, it is also possible to use voltages in the second voltage range as both the first voltage V1 and the second voltage V2.

[0183] Although the example described here is one in which the first voltage V1 is applied to the reset voltage line 36 when the illuminance on the photoelectric conversion unit 10 is less than a predetermined illuminance, and the relatively high second voltage V2 is applied to the reset voltage line 36 when the illuminance is equal to or greater than the predetermined illuminance, the relationship of the applied voltage to the illuminance is not limited to this example. The voltage supply circuit 150 may be driven so that the second voltage V2 is applied to the reset voltage line 36 when the illuminance on the photoelectric conversion unit 10 is less than the predetermined illuminance, and the relatively low first voltage V1 is applied to the reset voltage line 36 when the illuminance is equal to or greater than the predetermined illuminance. At this time, a voltage higher than the second voltage V2 may be supplied to the counter electrode 11.

[0184] (Second embodiment) FIG. 21A is a schematic diagram illustrating an exemplary configuration of a camera system according to a second embodiment of the present disclosure. 21A generally includes an image capturing device 100D and a voltage supply circuit 150D.

[0185] 1, the imaging device 100D shown in FIG. 21A is similar in that it includes a plurality of pixels Px, each having a photoelectric conversion unit 10 and an output circuit 20, and a detection circuit 130A electrically connected to the output circuit 20 of each pixel Px. In the configuration illustrated in FIG. 21A, the output circuit 20 and the detection circuit 130A are both formed on a semiconductor substrate 110. The photoelectric conversion unit 10, the output circuit 20, and the detection circuit 130A may be provided in the form of an integrated package.

[0186] 21A, the voltage supply circuit 150D is arranged in the camera system 200D in the form of, for example, a chip or a package, as an element separate from a package including, for example, the photoelectric conversion unit 10, the output circuit 20, and the detection circuit 130A. For example, the voltage supply circuit 150D may be formed on a substrate different from the semiconductor substrate 110 on which the pixels Px are arranged. However, similar to the first embodiment, the voltage supply circuit 150D is electrically connected to one of the counter electrode 11 and the pixel electrode 12 of each pixel Px.

[0187] The operation of the camera system 200D may be similar to that of the first embodiment. For example, the detection circuit 130A detects the level of the signal output from the output circuit 20 of each pixel Px. Based on a drive signal from the control circuit 160, the voltage supply circuit 150D applies a first voltage V1 to the voltage line 152 when the level of the output signal detected by the detection circuit 130A is equal to or higher than a predetermined voltage level. When the level of the output signal detected by the detection circuit 130A is lower than the predetermined voltage level, the voltage supply circuit 150D applies a second voltage V2 higher than the first voltage V1 to the voltage line 152.

[0188] As described above, it is not essential that the semiconductor substrate 110 on which the plurality of pixels Px are formed, the row scanning circuit 120, the detection circuit 130A, the voltage supply circuit 150D, and the control circuit 160 are all integrated into one chip or package. Some of these elements may be disposed in other packages or substrates, and such a camera system configuration can also provide the same functions as the image capture device according to the first embodiment.

[0189] 21B schematically illustrates another exemplary configuration of a camera system according to the second embodiment of the present disclosure. The main difference between camera system 200D illustrated in FIG. 21A and camera system 200E illustrated in FIG. 21B is that camera system 200E includes image capture device 100E instead of image capture device 100D. Compared to image capture device 100D, image capture device 100E includes detection circuit 130B instead of detection circuit 130A, and in this example, the output of detection circuit 130B is input to image processing circuit 164.

[0190] 21B, the image processing circuit 164 receives the output signal from the detection circuit 130B and compares the output signal from the detection circuit 130B with a predetermined threshold. That is, the image processing circuit 164 compares the input from the detection circuit 130B with a threshold stored in the memory 162, for example, to determine whether the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than a predetermined amount of light. Data indicating the result of the determination is passed to the voltage supply circuit 150D, for example.

[0191] When it is determined that the level of the signal output from the output circuit 20 of each pixel Px is equal to or higher than a predetermined level, in other words, that the amount of light incident on the photoelectric conversion unit 10 is equal to or higher than a predetermined amount of light, the voltage supply circuit 150D supplies a relatively low first voltage V1 to the voltage line 152. When it is determined that the amount of light incident on the photoelectric conversion unit 10 is lower than the predetermined amount of light, the voltage supply circuit 150D supplies a second voltage V2 to the voltage line 152.

[0192] 21B, voltage supply circuit 150D and image processing circuit 164 are arranged in camera system 200E as elements separate from image capture device 100E, for example, as separate chips or packages, which increases the degree of freedom in designing the voltage levels and / or voltage input timings used and allows for more flexible control. This provides the advantage of being able to avoid using higher voltages or increasing the chip size.

[0193] Fig. 22 schematically illustrates another exemplary configuration of a camera system according to the second embodiment of the present disclosure. A camera system 200F illustrated in Fig. 22 generally includes an image capturing device 100F and a light amount detecting device 130F.

[0194] The imaging device 100F is similar to the imaging device 100A shown in FIG. 1 in that it includes a plurality of pixels Px, each having a photoelectric conversion unit 10 and an output circuit 20, and a voltage supply circuit 150 electrically connected to the photoelectric conversion unit 10 of each pixel Px. The imaging device 100F further includes a detection circuit 130B electrically connected to the output circuit 20. The detection circuit 130B is similar to the detection circuit 130A described above in that it detects the level of a signal output from the output circuit 20 of each pixel Px. However, in this example, the detection circuit 130B does not have the function of comparing the detected signal level with a predetermined threshold, and instead mainly performs functions such as noise suppression signal processing and analog-to-digital conversion. In this example, the voltage supply circuit 150 is connected to a voltage line 152 connected to the counter electrode 11, similar to the configuration illustrated in FIG. 1, and is configured to selectively supply a first voltage V1 or a second voltage V2 to the counter electrode 11.

[0195] The light amount detection device 130F is disposed in the camera system 200F as a separate element from the imaging device 100F, which may be provided in the form of a single chip or package. The light amount detection device 130F includes, for example, a photodiode PD as part thereof and detects the amount of light incident on an imaging area formed by a plurality of pixels Px. The light amount detection device 130F may be, for example, a known illuminance sensor module including a photoelectric conversion element such as a photodiode and an illuminance sensor IC.

[0196] In the configuration illustrated in FIG. 22 , the control circuit 160 determines whether the amount of light incident on the photoelectric conversion unit 10 arranged in the imaging region is equal to or greater than a predetermined amount of light, for example, based on the output from the light amount detection device 130F. Similar to the first embodiment, the control circuit 160 further determines whether to cause the voltage supply circuit 150 to supply a first voltage V1 or a second voltage V2 to the voltage line 152, depending on the determination result of whether the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than the predetermined amount of light. Based on the drive signal from the control circuit 160, for example, if the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than the predetermined amount of light, the voltage supply circuit 150 applies the first voltage V1 to the voltage line 152. If the amount of light incident on the photoelectric conversion unit 10 is less than the predetermined amount of light, the voltage supply circuit 150 applies a second voltage V2 higher than the first voltage V1 to the voltage line 152.

[0197] Fig. 23 shows a modified example of the light amount detecting device. Compared to the example described with reference to Fig. 22, a camera system 200G shown in Fig. 23 has a light amount detecting device 130G that includes a light amount detecting circuit 138 instead of a photodiode PD.

[0198] In the configuration illustrated in FIG. 23, the light amount detection circuit 138 detects the voltage level of the output signal line S j That is, in this example, the light amount detection circuit 138 detects the level of the output signal from the output circuit 20 and compares it with the voltage level of the reference line 132. The comparison result is returned to the control circuit 160, and the control circuit 160 determines whether the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than a predetermined amount of light based on the detection result by the light amount detection circuit 138.

[0199] In this way, instead of directly measuring the amount of light using an illuminance sensor module or the like, information about the amount of light incident on the photoelectric conversion unit 10 may be obtained by detecting the level of a signal output from the pixel Px. For example, some or all of the multiple pixels Px arranged in the imaging area may function as an illuminance sensor. The light amount detection device 130G may obtain the output signal from the pixel Px in a wired or wireless manner.

[0200] Fig. 24 schematically illustrates another exemplary configuration of a camera system according to the second embodiment of the present disclosure. The camera system 200H illustrated in Fig. 24 generally includes an imaging device 100H including a plurality of pixels Px, each having a photoelectric conversion unit 10 and an output circuit 20, a voltage supply circuit 150D, and a light amount detection device 130F.

[0201] In this example, the voltage supply circuit 150D and the light intensity detection device 130F are provided outside the image capture device 100H as elements separate from the image capture device 100H. Similar to the example described with reference to Fig. 22, the control circuit 160 determines whether the amount of light incident on the photoelectric conversion unit 10 is equal to or greater than a predetermined amount of light, based on the amount of light detected by the light intensity detection device 130F. Depending on the determination result, the control circuit 160 applies either the first voltage V1 or the second voltage V2 from the voltage supply circuit 150D to the voltage line 152.

[0202] 23 may be applied instead of the light amount detecting device 130F. That is, the level of the signal output from the output circuit 20 of each pixel Px may be obtained, and based on the result of comparing the level of the signal from the output circuit 20 with a predetermined threshold, it may be determined whether the first voltage V1 or the second voltage V2 is to be output from the voltage supply circuit 150D.

[0203] (Voltage switching timing and subsequent processing) Next, a description will be given of correction processing according to the timing of switching the voltage applied to the voltage line 152. As will be described below, correction may be applied to the signal levels detected by the detection circuits 130A and 130B according to the timing of switching the voltage applied to the voltage line 152. A specific example of the correction processing will be described below using the above-mentioned image pickup device 100A as an example, but it goes without saying that similar correction processing can also be applied to the image pickup devices 100B and 100C and camera systems 200D to 200H.

[0204] 25 is a diagram for explaining the relationship between the timing of switching between the first voltage V1 and the second voltage V2 and the change in the level of the signal acquired by the detection circuit 130A that accompanies the voltage switching. In FIG. 25, the timing chart at the top shows the rising edge of the pulse of the vertical synchronization signal VD, and the timing chart below that shows the rising edge of the pulse of the horizontal synchronization signal HD. The timing chart one level below that shows the rising edge of the voltage V applied to the counter electrode 11 from the voltage line 152. ITO This shows the change in

[0205] In the timing chart shown in the second row of FIG. 25, the period from the rising edge of a pulse to the rising edge of the next pulse corresponds to one horizontal scanning period, 1H. During this 1H period, signals are read out from pixels Px belonging to one row among the plurality of pixels Px. In FIG. 25, rectangles extending in the horizontal direction schematically represent the operation of each row of the plurality of pixels Px. In FIG. 25, white rectangles represent the period for accumulating signal charges, i.e., the exposure period. Shaded rectangles represent the period for detecting the signal charges on the output signal line S by the detection circuit 130A. j 25 represents a period for reading out the voltage levels of the pixels Px. For simplicity, it is assumed here that there are five rows of pixels Px, and the operation of rows 0 to 4 is illustrated schematically. In FIG. 25, R0 to R4 correspond to rows 0 to 4, respectively.

[0206] In FIG. 25, the double-headed arrows at the bottom of the figure indicate frame periods. The start of each frame is the rising edge of the pulse of the vertical synchronization signal VD. In the example shown, at time tc during the j-th frame period, the voltage supply circuit 150 switches the voltage supplied to the counter electrode 11 from the second voltage V2 to a relatively lower first voltage V1. More specifically, during the exposure period of each row in the j-th frame period, the voltage applied to the voltage line 152 is switched to the first voltage V1.

[0207] 25, hatched rectangles schematically indicate periods during which the first voltage V1 is applied to the counter electrode 11 during the exposure period included in the jth frame period. As can be seen from FIG. 25, when the rolling shutter is applied and switching between the first voltage V1 and the second voltage V2 is performed during the exposure period of each row, a period during which signal charge is accumulated while the first voltage V1 is applied to the counter electrode 11 and a period during which signal charge is accumulated while the second voltage V2 is applied to the counter electrode 11 may coexist within one frame period. Furthermore, the ratio between the length of the period during which signal charge is accumulated while the first voltage V1 is applied to the counter electrode 11 and the length of the period during which signal charge is accumulated while the second voltage V2 is applied to the counter electrode 11 may differ for each row of the multiple pixels Px.

[0208] Therefore, under the operation shown in Figure 25, there is an advantage that the voltage switching does not affect frame periods other than the frame period in which the voltage switching is performed. However, on the other hand, vertical shading may occur in an image based on pixel signals acquired during the frame period in which the voltage switching is performed. In other words, brightness may vary from row to row. However, such vertical shading caused by voltage switching can be corrected by the processing described below.

[0209] The level of a signal output from a pixel Px is roughly proportional to the product of the sensitivity of the pixel Px and the length of the exposure period for that pixel Px. Here, as described with reference to FIG. 4 , the photoelectric conversion unit 10 in a typical embodiment of the present disclosure may have photoelectric conversion characteristics such that the photoelectric conversion efficiency η changes with a change in the potential difference ΔV between the counter electrode 11 and the pixel electrode 12. In other words, the sensitivity of the pixel Px changes depending on the voltage supplied from the voltage supply circuit 150 to the voltage line 152. Information on how the photoelectric conversion efficiency η of each pixel Px changes with a change in the potential difference ΔV can be obtained in advance by actual measurement or the like. Therefore, first, the product of the length T1 of the period during which signal charge accumulation is performed with the first voltage V1 applied to the counter electrode 11 and the sensitivity S1 of the pixel Px during that period is calculated. Next, the product of the length T2 of the period during which signal charge accumulation is performed with the second voltage V2 applied to the counter electrode 11 and the sensitivity S2 of the pixel Px during that period is calculated. Then, for example, a digital value representing the signal level is multiplied by a correction coefficient that makes the sum of these (T1 * S1 + T2 * S2) equal for each row. This makes it possible to cancel the effect of voltage switching on the image. That is, the longer the period indicated by the hatched rectangle in Figure 25, the greater the gain applied.

[0210] Such correction processing can be performed, for example, by the above-mentioned image processing circuit 164 or the control circuit 160. The correction coefficient is determined according to the magnitude of (T1*S1+T2*S2) and may be stored in advance in the memory 162 or the like.

[0211] FIG. 26 shows another example of the timing of switching between the first voltage V1 and the second voltage V2. In FIG. 26, the rectangles hatched with thick diagonal lines represent a period for so-called electronic shuttering, in which the reset transistor 26 is turned on to drain charge from the node FD. FIG. 26 shows an example in which electronic shuttering is performed row by row before the start of signal charge accumulation in the jth frame period. In this example, as schematically shown by the double-headed arrow ex in FIG. 26, the period from the end of electronic shuttering to the start of signal readout corresponds to the exposure period of the jth frame period.

[0212] As shown in Figure 26, even when switching between the first voltage V1 and the second voltage V2 is performed during the scanning period of the electronic shutter, the ratio between the length T1 of the period during which signal charge accumulation is performed with the first voltage V1 applied to the opposing electrode 11 and the length T2 of the period during which signal charge accumulation is performed with the second voltage V2 applied to the opposing electrode 11 may differ between rows of multiple pixels Px.

[0213] However, even when such an operation is applied, the value of the photoelectric conversion efficiency η with respect to the potential difference ΔV is known, and the control circuit 160 can obtain information regarding the timing of the electronic shutter, the timing of switching from the second voltage V2 to the first voltage V1, and the timing of signal readout. Therefore, as in the example described with reference to Fig. 25, a correction can be applied so that (T1*S1+T2*S2) is uniform for each row, and the occurrence of vertical shading in the image can be avoided.

[0214] Fig. 27 shows yet another example of the timing of switching between the first voltage V1 and the second voltage V2. Fig. 27 shows an example of operation in which switching between the first voltage V1 and the second voltage V2 is performed during a row scanning period for signal readout in the j-th frame period, as schematically indicated by a double-headed arrow rd in Fig. 27.

[0215] In FIG. 27, the hatched rectangle R4 schematically indicates the period during which the first voltage V1 is applied to the counter electrode 11 during the exposure period included in the jth frame period. Also, in FIG. 27, the hatched rectangles R0 and R1 schematically indicate the period during which the second voltage V2 is applied to the counter electrode 11 during the exposure period included in the (j+1)th frame period. As can be seen from FIG. 27, when switching between the first voltage V1 and the second voltage V2 is performed during the signal readout period of a certain frame period, the sensitivity modulation caused by the voltage switching also affects the accumulation of signal charge in the next frame period. In this case, too, vertical shading in the image can be avoided by applying a correction to the jth frame period and the (j+1)th frame period so that (T1*S1+T2*S2) is equal for each row.

[0216] 28 is a diagram illustrating the relationship between the timing of switching between the first voltage V1 and the second voltage V2 and the change in the level of the signal acquired by the detection circuit 130A due to the voltage switching when the global shutter is applied by controlling the potential difference ΔV. In the example shown in FIG. 28, the second voltage V2 is selectively applied to the counter electrode 11 during the period from the end of signal readout for the (j−1)th frame period to the start of signal readout for the jth frame period. Furthermore, the first voltage V1 is selectively applied to the counter electrode 11 during the period from the end of signal readout for the jth frame period to the start of signal readout for the (j+1)th frame period. Furthermore, the first voltage V1 is selectively applied to the counter electrode 11 during the period from the end of signal readout for the (j+1)th frame period to the start of signal readout for the (j+2)th frame period. During other periods, the potential of the counter electrode 11 is set to a positive potential near 0 V so that the potential difference ΔV is substantially 0 V.

[0217] FIG. 28 shows an example of operation when an electrical global shutter such as that described in the above-mentioned Japanese Patent No. 6202512 is applied. In FIG. 28, the period indicated by the white rectangle corresponds to the period of substantial accumulation of signal charge, i.e., the exposure period. In this example, it can be said that switching from the second voltage V2 to the first voltage V1 is carried out during the (j+1)th frame period, but since substantial accumulation of signal charge does not occur during the period when the potential of the counter electrode 11 is near 0V, no vertical shading occurs due to switching of the voltage applied to the counter electrode 11. Therefore, the above-mentioned correction process is unnecessary. In this way, the correction process is unnecessary depending on the operation mode of the imaging device. Therefore, the above-mentioned correction process is unnecessary. Whether or not to perform the correction process in response to switching between the first voltage V1 and the second voltage V2 may be configured to be switchable based on the operation mode of the imaging device, a user command, or the like.

[0218] Also, when capturing an image at a sufficiently high frame rate, the correction for making (T1*S1+T2*S2) uniform for each row can be omitted. Fig. 29 is a diagram for explaining an example of the relationship between the timing of switching between the first voltage V1 and the second voltage V2 and the output from the image capturing device 100A. In Fig. 29, the voltage V ITO The rectangles drawn below the chart showing the changes in the image data schematically indicate whether the image data is valid or invalid based on the signal level detected by the detection circuit 130A.

[0219] 29, switching between the first voltage V1 and the second voltage V2 is performed during the exposure period of each row in the j-th frame period, as in the example described with reference to Fig. 25. Therefore, if no correction processing is performed, vertical shading due to the voltage switching may occur in an image based on pixel signals acquired in the j-th frame period.

[0220] However, when the frame rate is sufficiently high, as shown in FIG. 29, even if pixel signals acquired during a frame period in which vertical shading due to voltage switching may occur—that is, the jth frame period in this example—are discarded as invalid data, the impact is small. Thus, when the frame rate is sufficiently high, pixel signals acquired during a frame period in which vertical shading may occur may be discarded as invalid data, and pixel signals acquired during other frame periods may be selectively acquired as valid data. In this specification, the process of discarding pixel signals acquired during a frame period in which vertical shading may occur as invalid data is referred to as masking. This type of masking is also effective when it is difficult to secure the necessary area to implement a circuit that performs correction so that (T1*S1+T2*S2) is uniform across each row.

[0221] 30 shows an example of application of masking processing when switching between the first voltage V1 and the second voltage V2 is performed during a row scanning period for signal readout. As described with reference to FIG. 27, when switching between the first voltage V1 and the second voltage V2 is performed during a signal readout period in a certain frame period, sensitivity modulation due to the voltage switching also affects the accumulation of signal charge in the next frame period. Therefore, when switching between the first voltage V1 and the second voltage V2 is performed during a row scanning period for signal readout in the jth frame period, pixel signals acquired in the jth frame period and pixel signals acquired in the (j+1)th frame period may be subject to masking processing as invalid data, as shown schematically in FIG. 30.

[0222] The above-described masking process may be performed as needed, and it is useful to be able to switch whether or not to perform the masking process. The masking process may be performed, for example, by a logic circuit arranged in the control circuit 160 or the image processing circuit 164. Data selection may also be performed by an analog-to-digital conversion circuit or the like in the detection circuit 130A.

[0223] (In the automatic exposure setting, the detected exposure amount is reflected in the potential difference ΔV) The voltages that the above-described voltage supply circuits 150, 150D, and 154 can supply to the counter electrode 11 or the pixel electrode 12 do not need to be limited to two values, the first voltage V1 and the second voltage V2. The voltage supply circuits 150, 150D, and 154 may be configured to selectively apply one of three or more voltage values ​​to the voltage line 152 depending on, for example, the environment during shooting. For example, as described below, the voltage supply circuit 150, 150D, or 154 may be configured to switch between three or more voltage values ​​and apply them to the voltage line 152 depending on the exposure amount, in other words, the illuminance on the photoelectric conversion unit 10.

[0224] 31 is a diagram illustrating an example of a processing sequence in automatic exposure setting that can be applied to an image capture device and a camera system according to an embodiment of the present disclosure. The graph shown in FIG. 31 illustrates an example of changes in exposure amount for each frame period.

[0225] The exposure amount indicated on the vertical axis of FIG. 31 can be calculated, for example, as follows. As schematically shown in FIG. 32, an area including the photoelectric conversion units 10 of multiple pixels Px is defined as an imaging area Rm, and any area of ​​the imaging area Rm including the photoelectric conversion units 10 of one or more pixels Px is defined as a detection area Rd. In this case, the exposure amount indicated on the vertical axis of FIG. 31 can be calculated by detecting the levels of signals from the output circuits 20 of the pixels Px located in the detection area Rd for each frame period. For example, the average value of the levels of signals from the output circuits 20 of the pixels Px located in the detection area Rd can be made to correspond to the exposure amount. Instead of detecting the signal levels using the detection circuit 130A or 130B, the exposure amount for each frame period may be estimated using a light intensity detection device 130F or 130G, etc.

[0226] Fig. 33 shows an example of a process for changing the voltage output from the voltage supply circuit in accordance with the detected exposure amount. Fig. 33 shows a graph of the change in exposure amount for each frame period and the voltage V applied to the counter electrode 11 from the voltage line 152. ITO33 is shown in one figure together with a graph showing the change in Ex1. The graph shown in the upper part of Fig. 33 is the same as the graph shown in Fig. 31. In the example shown in Fig. 33, when an exposure amount exceeding a predetermined threshold Ex1 is detected in a certain frame period, the voltage output from the voltage supply circuit 150 is switched to a lower voltage.

[0227] In the example shown in FIG. 33, for example, during the third frame period, the acquired exposure amount exceeds a certain value Ex1. Therefore, the voltage supply circuit 150 switches the voltage supplied to the voltage line 152 from the second voltage V2 to a lower third voltage V3. Therefore, during the next fourth frame period, signal charge accumulation is performed with the relatively low third voltage V3 applied to the counter electrode 11. If the photoelectric conversion unit 10 has photoelectric conversion characteristics such as those shown in FIG. 4, the sensitivity of the pixel Px decreases as the voltage applied to the photoelectric conversion unit 10 decreases. Therefore, overexposure can be avoided.

[0228] In this example, the exposure amount acquired in the fourth frame period still exceeds the threshold value Ex1. Therefore, the voltage supply circuit 150 further reduces the voltage supplied to the voltage line 152 and applies a fourth voltage V4 to the photoelectric conversion unit 10. If the exposure amount acquired in the fifth frame period still exceeds the threshold value Ex1, the voltage supply circuit 150 applies an even lower fifth voltage V5 to the voltage line 152, as shown in FIG. 33. In this example, the exposure amount acquired in the sixth frame period is equal to or less than the threshold value Ex1, so the voltage applied to the counter electrode 11 remains at the fifth voltage V5 in the seventh frame period. The first voltage V1 described above may be any one of the third voltage V3 to fifth voltage V5, which are lower than the second voltage V2.

[0229] In this way, the voltage output from the voltage supply circuit 150 may be switched in multiple steps or continuously so that the amount of exposure light acquired in the previous frame period is reflected in the photoelectric conversion efficiency in the next frame period. Furthermore, when an amount of exposure light less than a predetermined threshold value Ex2 is detected in a certain frame period, a process may be executed in which the voltage output from the voltage supply circuit 150 is switched to a higher voltage.

[0230] 34 shows another example of a process for changing the voltage output from the voltage supply circuit in accordance with the detected exposure amount. As in FIG. 33, FIG. 34 also shows a graph of the change in exposure amount for each frame period and the voltage V applied to the counter electrode 11 from the voltage line 152. ITO The graph showing the change in the temperature is also shown in one figure.

[0231] In the example shown in FIG. 34, when an exposure amount below a predetermined threshold Ex2 is detected during a certain frame period, the voltage output from the voltage supply circuit 150 is switched to a higher voltage. In the example shown in FIG. 34, for example, the exposure amount acquired during the third frame period is less than a certain value Ex2. Therefore, the voltage supply circuit 150 increases the voltage supplied to the voltage line 152 from the fifth voltage V5 to the fourth voltage V4. Because the exposure amount acquired during the fourth frame period is also below the threshold Ex2, the voltage supply circuit 150 changes the voltage supplied to the voltage line 152 to a higher third voltage V3. If the exposure amount acquired during the fifth frame period is also below the threshold Ex2, the voltage supply circuit 150 applies an even higher second voltage V2 to the voltage line 152. In this example, because the exposure amount acquired during the sixth frame period is between the threshold Ex2 and the threshold Ex1, the second voltage V2 is applied to the counter electrode 11 during the seventh frame period.

[0232] By setting a second threshold Ex2 that serves as a criterion for determining whether or not to increase the voltage output from the voltage supply circuit 150, it is possible to avoid deterioration in image quality due to insufficient exposure. The second threshold may be the same as the first threshold, or may be equal to or less than the first threshold. In the examples shown in FIGS. 31 to 34, the voltage to be applied to the counter electrode 11 or the pixel electrode 12 in the next frame period is determined based on the result of comparing the exposure acquired in the immediately preceding frame period with the threshold, but the voltage to be applied to the counter electrode 11 or the pixel electrode 12 may also be determined based on two or more comparison results.

[0233] Fig. 35 shows yet another example of a process for changing the voltage output from the voltage supply circuit 150 in accordance with the detected exposure amount. In Fig. 35, when the exposure amount acquired in the previous frame period exceeds the threshold value Ex1 two consecutive times, the voltage output from the voltage supply circuit 150 is switched to a lower voltage.

[0234] For example, in the third frame period, the acquired exposure amount exceeds the threshold value Ex1. At this point, the voltage output from the voltage supply circuit 150 is not switched. In this example, the exposure amount acquired in the fourth frame period does not exceed the threshold value Ex1. Therefore, the voltage output from the voltage supply circuit 150 remains at the second voltage V2.

[0235] The next time the exposure amount exceeds the threshold value Ex1 is in the seventh frame period. At this point, the voltage output from the voltage supply circuit 150 is not switched. In this example, the exposure amounts acquired in the following eighth to tenth frame periods all exceed the threshold value Ex1. Therefore, after the exposure amount is acquired in the eighth frame period, after the exposure amount is acquired in the ninth frame period, and after the exposure amount is acquired in the tenth frame period, the voltage output from the voltage supply circuit 150 is sequentially reduced.

[0236] In this way, if the exposure amount acquired in the previous frame period exceeds the threshold or falls below the threshold multiple times in succession, the voltage output from the voltage supply circuit 150 may be switched to a lower or higher voltage. This processing can reduce the possibility of acquiring an overexposed or underexposed image, for example, when a camera flash is turned on or when shooting under a light source that periodically flickers.

[0237] (Correction of Linearity According to Voltage Applied to Photoelectric Conversion Unit 10) FIG. 36 shows a schematic example of the change in the output of the detection circuit 130A with increasing exposure dose. In FIG. 36, the solid line L1 shows an example of the change in the output of the detection circuit 130A with increasing exposure period under a constant illuminance, that is, with increasing exposure dose, obtained when a voltage within the second voltage range is applied to the counter electrode 11. The dashed line L2 shows the change in the output obtained when a lower voltage within the second voltage range is applied to the counter electrode 11. A line L3 shows an exemplary change in the output of the detection circuit 130A with increasing exposure dose when a voltage in the first voltage range is applied to the counter electrode 11.

[0238] As explained with reference to FIG. 11 , the change in the photoelectric conversion efficiency η in the photoelectric conversion layer 13 with respect to the change in the potential difference ΔV applied between the counter electrode 11 and the pixel electrode 12 may not be linear. Therefore, depending on the magnitude of the voltage applied to the counter electrode 11 or the pixel electrode 12, the output of the detection circuit 130A may not increase proportionally with an increase in the exposure period. This tendency is particularly likely to occur when the potential difference ΔV is small. In the example shown in FIG. 36 , the graph indicated by the solid line L1, which corresponds to a case where the voltage applied to the counter electrode 11 or the pixel electrode 12 is relatively large, is linear. The graphs indicated by the dashed lines L2 and L3, which correspond to a case where the voltage applied to the counter electrode 11 or the pixel electrode 12 is relatively small, deviate more from the straight line as the exposure amount increases.

[0239] Therefore, for example, the output from the detection circuit 130A may be corrected to correct the deviation of the output from the detection circuit 130A from a straight line as the exposure period increases. Figure 37 shows a schematic overview of the linearity compensation process. For example, a table may be prepared for converting the output from the detection circuit 130A into an appropriate digital value for each voltage value that can be output from the voltage supply circuit 150.

[0240] In this example, three correction tables 1 to 3 corresponding to voltages that can be output from the voltage supply circuit 150 are stored in memory 162. For example, the control circuit 160 receives, for example, an output from the detection circuit 130A after analog-to-digital conversion, and applies a correction table according to the specific value of the voltage applied from the voltage supply circuit 150 to the photoelectric conversion unit 10. The selector 165 in FIG. 37 is a circuit that selects which of the correction tables 1 to 3 to apply, or whether to apply no correction table, according to the value of the voltage supplied from the voltage supply circuit 150 to the photoelectric conversion unit 10. The corrected output is passed to the image processing circuit 164, where it is subjected to, for example, gamma processing or the like.

[0241] Fig. 38 shows an example of the correction table. In the correction table shown in Fig. 38, a digital value after linearity compensation is described for each digital value that is output from the detection circuit 130A. For example, when N is input as a sensor output from the detection circuit 130A, the control circuit 160 outputs X to the image processing circuit 164. Note that, as shown in graph L1 in Fig. 36, when a voltage that does not require linearity compensation is selected as the voltage to be applied from the voltage supply circuit 150 to the photoelectric conversion unit 10, the sensor output from the detection circuit 130A is passed directly to the image processing circuit 164.

[0242] By applying such linearity compensation processing, as shown in FIG. 36, the characteristics shown in graph L2 can be corrected as shown by the solid line A2 in FIG. 36, and the characteristics shown in graph L3 can be corrected as shown by the solid line A3. The linearity compensation processing may be performed by image processing circuit 164. Instead of preparing a table for the output before gamma correction, gamma correction may be performed using a γ value that takes into account deviation from a straight line. Alternatively, instead of converting digital values ​​using a table, linearity may be compensated for by multiplying the sensor output from detection circuit 130A by an appropriate coefficient.

[0243] It should be noted that the deviation in linearity as described above may differ for each imaging device or each camera system. Fig. 39 is a diagram for explaining the difference in deviation in linearity for each imaging device or each camera system. In Fig. 39, dashed line M1 indicates an exemplary change in the output of the detection circuit 130A with respect to an increase in the amount of exposure for a certain imaging device, and dashed line M2 indicates an exemplary change in the output of the detection circuit 130A with respect to an increase in the amount of exposure for another certain imaging device. Between these imaging devices, the output of the detection circuit 130A with respect to an increase in the amount of exposure is For example, it is useful to have a match as shown by the line M12 in FIG.

[0244] FIG. 40 shows a schematic overview of linearity compensation processing for canceling differences between image pickup devices or camera systems. For example, if there are image pickup devices of sample 1 and sample 2, data related to the photoelectric conversion characteristics of each of samples 1 and 2, as shown in FIG. 4, is acquired in advance using a tester or the like. Furthermore, correction values ​​for each sample are calculated based on the acquired data, and the correction values ​​are stored in memory 162, for example, in the form of a table. FIG. 40 shows an overview of linearity compensation processing for, for example, sample 1. Correction tables 11 to 13 for converting the output from detection circuit 130A into an appropriate digital value for each voltage value that can be output from voltage supply circuit 150 are written into memory 162 of the image pickup device of sample 1. Note that memory 162 is typically a nonvolatile memory.

[0245] Fig. 41 shows an example of a correction table stored in memory 162 of the image pickup device of sample 1, and Fig. 42 shows an example of a correction table stored in memory 162 of the image pickup device of sample 2. When such a correction table is applied, for example, in response to a sensor output N from detection circuit 130A, control circuit 160 of the image pickup device of sample 1 outputs digital value X, whereas control circuit 160 of the image pickup device of sample 2 outputs digital value Y. By applying such linearity compensation processing adapted for each image pickup device or each camera system, it is possible to cancel the effects of differences in photoelectric conversion characteristics due to individual differences between image pickup devices or camera systems, as shown in the example of Fig. 39.

[0246] As described above, a correction value calculated based on data related to photoelectric conversion characteristics can be prepared for each voltage value that can be output from the voltage supply circuit 150. However, it is possible that exposure will be performed for a time longer than the expected exposure time, or that the voltage output from the voltage supply circuit 150 will include a voltage that was not expected.

[0247] Fig. 43 shows another example of the correction table stored in memory 162, and Fig. 44 shows plots of output values ​​described in the correction table of Fig. 43. In Fig. 44, white circles indicate plots related to correction values ​​applied when voltage Va is applied from voltage supply circuit 150 to photoelectric conversion unit 10, white triangles indicate plots related to correction values ​​applied when voltage Vb is applied from voltage supply circuit 150 to photoelectric conversion unit 10, and white rectangles indicate plots related to correction values ​​applied when voltage Vc is applied from voltage supply circuit 150 to photoelectric conversion unit 10.

[0248] For example, if the value of P13 is not previously obtained in the correction table of FIG. 43, the value of P13 can be calculated by linear interpolation using, for example, correction values ​​P11 and P12. Furthermore, if an unexpected voltage is applied from voltage supply circuit 150 to voltage line 152, for example, a straight line representing the output characteristics of detection circuit 130A relative to an increase in exposure dose can be calculated from the discrete values ​​described in the correction table. As illustrated in FIG. 44, if parameters representing straight line Pt are calculated in advance, a correction value can be calculated after the fact when, for example, an exposure dose between t2 and t3 and a voltage between Vb and Vc is applied to photoelectric conversion unit 10, and the correction value can be used to compensate for linearity.

[0249] Fig. 45 shows a schematic overview of linearity compensation processing including interpolation processing. As shown in Fig. 45, the control circuit 160 may include an interpolation processing circuit 166 that performs such linear interpolation as part thereof. [Industrial Applicability]

[0250] The embodiments of the present disclosure are applicable to photodetection devices, image sensors, and the like. For example, the imaging device or camera system of the present disclosure can be used in a digital single-lens reflex camera, a digital mirrorless camera, or the like. The present invention can be used in digital still cameras such as single-lens cameras or digital video cameras. Alternatively, the present invention can be used in various camera systems or sensor systems, including, for example, professional cameras for broadcasting, medical cameras, or surveillance cameras. By appropriately selecting the material of the photoelectric conversion layer, it is also possible to acquire images using infrared light. An imaging device that captures images using infrared light can be used, for example, in security cameras, cameras mounted on vehicles, and the like. A vehicle-mounted camera can be used, for example, as an input to a control device to ensure safe vehicle driving. Alternatively, the present invention can be used to assist an operator in ensuring safe vehicle driving. [Explanation of symbols]

[0251] 10 Photoelectric conversion unit 11 Counter electrode 12 pixel electrode 13 Photoelectric conversion layer 15 3rd electrode 20 Output circuit 22 Signal detection transistor 24 address transistor 26 Reset transistor 32 Power line 36 Reset voltage line 100A~100F, 100H Imaging device 110 Semiconductor substrate 111~115 Impurity region 120 row scanning circuit 130A, 130B detection circuit 130F, 130G Light quantity detection device 132 Reference line 134 Comparator 138 Light intensity detection circuit 150, 150D, 154 Voltage supply circuit 152 Voltage Line 160 Control circuit 162 memory 164 Image processing circuit 166 Interpolation processing circuit 200D~200H Camera System Px, Px1, Px2 pixels S j Output signal line

Claims

1. a photoelectric conversion unit including a first electrode, a second electrode, and a photoelectric conversion layer between the first electrode and the second electrode; a correction circuit that corrects a signal corresponding to a change in potential of the second electrode depending on the amount of incident light; Equipped with the photoelectric conversion unit has a photoelectric conversion characteristic in which a rate of change in photoelectric conversion efficiency of the photoelectric conversion unit with respect to a bias voltage when the bias voltage between the first electrode and the second electrode is in a first voltage range is greater than a rate of change in photoelectric conversion efficiency of the photoelectric conversion unit with respect to the bias voltage when the bias voltage is in a second voltage range that is greater than the first voltage range, when the photoelectric conversion efficiency when the bias voltage is at its maximum value during operation is normalized to 1, the second voltage range is a bias voltage range in which the normalized photoelectric conversion efficiency is 0.7 or more, and the first voltage range is a bias voltage range in which the normalized photoelectric conversion efficiency is less than 0.7, a first voltage is supplied to the first electrode such that the bias voltage is in the first voltage range; the first voltage is a constant voltage during exposure, the correction circuit corrects the signal so that the change in output relative to the amount of incident light is linear; Camera system.

2. the correction circuit includes a memory; The memory stores a correction coefficient according to the amount of light. The camera system of claim 1 .

3. Further comprising a semiconductor substrate; the photoelectric conversion unit is located on the semiconductor substrate; 3. The camera system according to claim 1.

4. further comprising an image processing circuit; the image processing circuit performs gamma correction on the signal output from the correction circuit; 3. The camera system according to claim 1.

5. The photoelectric conversion layer contains an organic material.

3. The camera system according to claim 1.

6. Further comprising a voltage supply circuit; the voltage supply circuit supplies the first voltage to the first electrode; 3. The camera system according to claim 1.

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