JP2021114611A - Imaging device and image acquisition device - Google Patents

Abstract

To provide a multi-layered imaging device capable of varying sensitivity.SOLUTION: The imaging device of the present disclosure has a pixel and a voltage application circuit. The pixel includes an upper electrode, an auxiliary electrode, a pixel electrode that collects holes as signal charges, an auxiliary electrode, and a photoelectric conversion layer positioned between the upper electrode and the pixel electrode. The voltage application circuit can selectively apply the first voltage and the second voltage to the auxiliary electrode. The first voltage and the second voltage are smaller than the voltage applied to the upper electrode.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an image pickup apparatus and an image acquisition apparatus.

A laminated image pickup device has been proposed as a MOS (Metal Oxide Semiconductor) type image pickup device. In the laminated image pickup apparatus, a photoelectric conversion film is laminated on the outermost surface of the semiconductor substrate, and the electric charge generated by the photoelectric conversion is accumulated in the charge storage region in the photoelectric conversion film. The image pickup apparatus reads out the accumulated charge using a CCD (Charge Coupled Device) circuit or a CMOS (Complementary MOS) circuit in the semiconductor substrate. For example, Patent Document 1 discloses such an imaging device.

JP-A-2009-164604

The imaging device is used in various environments. For example, a surveillance or in-vehicle imaging device is required to perform high-quality shooting even in a shooting environment in which the brightness varies greatly. Therefore, in the conventional stacked image pickup device, an image pickup device capable of changing the sensitivity has been required. One non-limiting exemplary embodiment of the present application provides a stacked imaging device with variable sensitivity.

An image pickup apparatus according to an exemplary embodiment, which is not limited to the present application, electrically connects a charge detection circuit, a pixel electrode and an auxiliary electrode provided on a substrate, and the charge detection circuit and the pixel electrode. At least two voltages with respect to the unit pixel cell including the charged charge storage node, the photoelectric conversion layer located on the pixel electrode and the auxiliary electrode, and the upper electrode located on the photoelectric conversion layer, and the auxiliary electrode. It is provided with a voltage application circuit capable of applying the above.

According to one aspect of the present disclosure, it is possible to provide an imaging device whose sensitivity can be adjusted.

FIG. 1 is a schematic view showing an example of the circuit configuration of the image pickup apparatus 101 according to the first embodiment. FIG. 2 is a schematic view showing a typical example of a cross section of a unit pixel cell in the image pickup apparatus according to the first embodiment. FIG. 3 is a schematic plan view showing an example of the shapes of the pixel electrode and the auxiliary electrode. FIG. 4A is a schematic cross-sectional view showing an example of a region for capturing electric charge formed in the photoelectric conversion layer when a sensitivity adjusting voltage is applied to the auxiliary electrode. FIG. 4B is a schematic plan view showing an example of a region for capturing electric charges formed in the photoelectric conversion layer when a sensitivity adjusting voltage is applied to the auxiliary electrode. FIG. 4C is a schematic cross-sectional view showing another example of a region for capturing electric charges formed in the photoelectric conversion layer when a sensitivity adjusting voltage is applied to the auxiliary electrode. FIG. 4D is a schematic plan view showing another example of a region for capturing electric charges formed in the photoelectric conversion layer when a sensitivity adjusting voltage is applied to the auxiliary electrode. FIG. 5 is a schematic diagram showing an exemplary relationship between the sensitivity adjustment voltage and the sensitivity. FIG. 6A shows an example of a region for capturing electric charges formed in the photoelectric conversion layer when the sensitivity adjustment voltage V1 is applied to the auxiliary electrode, and the photoelectric conversion layer when the sensitivity adjustment voltage V2 is applied to the auxiliary electrode. It is a schematic plan view which shows together with an example of the region for capturing charge formed in. FIG. 6B shows another example of a region for capturing electric charges formed in the photoelectric conversion layer when the sensitivity adjustment voltage V1 is applied to the auxiliary electrode, and photoelectric when the sensitivity adjustment voltage V2 is applied to the auxiliary electrode. It is a schematic plan view which shows together with another example of the region for capturing charge formed in the conversion layer. FIG. 6C is a schematic plan view showing an example of a region for capturing electric charges formed in the photoelectric conversion layer when a sensitivity adjustment voltage V1 satisfying V1 <0 is applied to the auxiliary electrode. FIG. 6D shows an example of a region for capturing electric charge formed in the photoelectric conversion layer when the sensitivity adjustment voltage V1 is applied to the auxiliary electrode when electrons are used as signal charges, and sensitivity adjustment to the auxiliary electrode. It is a schematic plan view which shows also an example of the region for capturing an electric charge which is formed in a photoelectric conversion layer when a voltage V2 is applied. FIG. 7 is a timing chart showing an example of the timing of changes in the sensitivity adjustment voltage and the reset gate voltage of the image pickup apparatus according to the first embodiment. FIG. 8 is a timing chart showing another example of the timing of changes in the sensitivity adjustment voltage and the reset gate voltage of the image pickup apparatus according to the first embodiment. FIG. 9 is a timing chart showing still another example of the timing of changes in the sensitivity adjustment voltage and the reset gate voltage of the image pickup apparatus according to the first embodiment. FIG. 10 is a diagram for explaining an example of operation in an image pickup apparatus having a flash. FIG. 11 is a timing chart showing an example of the timing of changes in the sensitivity adjustment voltage, the voltage of the upper electrode, and the reset gate voltage of the image pickup apparatus according to the first embodiment. FIG. 12A is a schematic view showing an example of the planar structure of the pixel electrode and the auxiliary electrode in the image pickup apparatus according to the second embodiment. FIG. 12B is a timing chart showing an example of the timing of changes in the sensitivity adjustment voltage and the reset gate voltage of the image pickup apparatus according to the second embodiment. FIG. 12C is a timing chart showing another example of the timing of changes in the sensitivity adjustment voltage and the reset gate voltage of the image pickup apparatus according to the second embodiment. FIG. 13A is a schematic view showing another example of the planar structure of the pixel electrode and the auxiliary electrode in the image pickup apparatus according to the second embodiment. FIG. 13B is a timing chart showing still another example of the timing of changes in the sensitivity adjustment voltage and the reset gate voltage of the image pickup apparatus according to the second embodiment. FIG. 14 is a schematic view showing an example of the circuit configuration of the image pickup apparatus according to the third embodiment. FIG. 14B is a schematic view showing an example of another configuration of the image pickup apparatus according to the third embodiment. FIG. 15 is a schematic view showing an example of still another configuration of the image pickup apparatus according to the third embodiment. FIG. 16 is a plan view showing an example of arrangement of pixel electrodes and auxiliary electrodes in an image pickup apparatus having an input interface 74. FIG. 17 is a schematic view showing an example of the circuit configuration of the image pickup apparatus according to the fourth embodiment. FIG. 18 is a plan view showing an example of arrangement of pixel electrodes and auxiliary electrodes in the image pickup apparatus according to the fourth embodiment. FIG. 19 is a plan view showing another example of the arrangement of the pixel electrode and the auxiliary electrode in the image pickup apparatus according to the fourth embodiment. FIG. 20 is a schematic view showing an example of an electrical connection between the unit pixel cell 14E including the pixel electrode 50 and the auxiliary electrode 61E and the voltage application circuit 60. FIG. 21 is a schematic view showing an example of a cross section of the unit pixel cell 14E including the pixel electrode 50 and the auxiliary electrode 61E. FIG. 22 is a schematic view showing an example of the circuit configuration of the image pickup apparatus according to the fifth embodiment. FIG. 23 is a plan view showing an example of arrangement of pixel electrodes and auxiliary electrodes in the image pickup apparatus according to the sixth embodiment. FIG. 24A is a schematic cross-sectional view showing an example of a region 51A for capturing electric charges formed in the photoelectric conversion layer 51 of the unit pixel cell 14G. FIG. 24B is a schematic showing an example of a region 51A for capturing electric charge in a state where the second sensitivity adjustment voltage is applied to the sub-auxiliary electrode 61a and the first sensitivity adjustment voltage is applied to the sub-auxiliary electrode 61d. It is a cross-sectional view. FIG. 25A is a block diagram showing an example of the configuration of the image acquisition device according to the seventh embodiment. FIG. 25B is a schematic view showing an example of the configuration of the lighting system in the image acquisition device according to the seventh embodiment. FIG. 26A is a diagram for explaining an exemplary procedure for acquiring an image by an image acquisition device when a sensitivity adjustment voltage Vk is applied to the auxiliary electrode. FIG. 26B is a diagram for explaining an exemplary procedure for acquiring an image by an image acquisition device when a sensitivity adjustment voltage Vk is applied to the auxiliary electrode. FIG. 27 is a schematic view showing an example of pixel arrangement of a plurality of captured images when a sensitivity adjustment voltage Vk is applied to the auxiliary electrodes. FIG. 28A is a schematic view showing an example of the relationship between the illumination direction and the light beam transmitted through the subject and incident on the region for capturing the electric charge when the sensitivity adjustment voltage Vh is applied to the auxiliary electrode. FIG. 28B is a schematic diagram showing another example of the relationship between the light beam transmitted through the subject and incident on the region for capturing the electric charge when the sensitivity adjustment voltage Vh is applied to the auxiliary electrode and the illumination direction. be. FIG. 28C is a schematic view showing still another example of the relationship between the light beam transmitted through the subject and incident on the region for capturing the electric charge when the sensitivity adjustment voltage Vh is applied to the auxiliary electrode and the illumination direction. Is. FIG. 29 is a schematic diagram showing an example of pixel arrangement of a plurality of captured images when a sensitivity adjustment voltage Vh is applied to the auxiliary electrodes. FIG. 30 is a diagram showing another example of the configuration of the lighting system in the image acquisition device according to the seventh embodiment.

The outline of one aspect of the present disclosure is as follows.

[Item 1]
A charge detection circuit, a pixel electrode and an auxiliary electrode provided on a substrate, a charge storage node electrically connected to the charge detection circuit and the pixel electrode, and a photoelectric conversion layer located on the pixel electrode and the auxiliary electrode. An imaging device including a unit pixel cell including an upper electrode located on a photoelectric conversion layer, and a voltage application circuit capable of applying at least two voltages to an auxiliary electrode.

According to this configuration, two or more different voltages can be selectively or simultaneously applied to the auxiliary electrodes.

[Item 2]
The imaging apparatus according to item 1, further comprising a plurality of unit pixel cells, wherein the plurality of unit pixel cells are arranged one-dimensionally or two-dimensionally.

[Item 3]
The imaging apparatus according to item 1 or 2, wherein the voltage application circuit selectively applies a first voltage and a second voltage larger than the first voltage to the auxiliary electrodes.

According to this configuration, the amount of signal charge captured by the auxiliary electrode can be controlled by switching the voltage applied to the auxiliary electrode between the first voltage and the second voltage. Therefore, by switching the voltage applied to the auxiliary electrode, it is possible to adjust the sensitivity of the image pickup apparatus and prevent color mixing.

[Item 4]
The imaging according to item 3, wherein the charge detection circuit includes a reset transistor for setting the pixel electrode to the reset voltage at a predetermined timing, and the reset voltage is larger than the first voltage and smaller than the second voltage. Device.

According to this configuration, there is an effect that the swing width of the size of the region where the holes that can move to the pixel electrode are distributed can be widely set by the sensitivity adjustment voltage.

[Item 5]
The image pickup apparatus according to item 3, wherein the charge detection circuit includes a reset transistor for setting a pixel electrode to a reset voltage at a predetermined timing, and the reset voltage is larger than a second voltage.

According to this configuration, when the signal charge is a negative charge, there is an effect that imaging with priority given to sensitivity and imaging with good color reproducibility while maintaining sensitivity are compatible.

[Item 6]
The image pickup apparatus according to item 3, wherein the charge detection circuit includes a reset transistor for setting a pixel electrode to a reset voltage at a predetermined timing, and the reset voltage is smaller than the first voltage.

According to this configuration, when the signal charge is a positive charge, there is an effect that imaging with priority given to sensitivity and imaging with good color reproducibility while maintaining sensitivity are compatible.

[Item 7]
The imaging apparatus according to item 3, wherein at least one of the first voltage and the second voltage is a negative voltage.

According to this configuration, when a negative voltage is used as the voltage for driving the transistor in the pixel, the generating circuit for generating this negative voltage can be used as a voltage applying circuit for applying a voltage to the auxiliary electrode, and the peripheral circuit can be used. It has the effect of reducing the scale and simplifying the configuration of peripheral circuits.

[Item 8]
The imaging according to any one of items 1 to 7, further comprising a light amount detection circuit that detects the amount of light per unit area incident on the photoelectric conversion layer, and the voltage application circuit applies a voltage based on the detection result of the light amount detection circuit. Device.

According to this configuration, a voltage is applied to the auxiliary electrode based on the detection result of the light amount detection circuit, so that it is possible to take a picture with more appropriate sensitivity.

[Item 9]
The imaging device according to any one of items 1 to 8, further comprising a memory for holding a value of a voltage applied at the time of imaging on an auxiliary electrode.

According to this configuration, the value of the sensitivity adjustment voltage used for photographing can be left as information accompanying the image data.

[Item 10]
Item 2. The imaging apparatus according to item 2, wherein the auxiliary electrodes are separated for each unit pixel cell.

According to this configuration, the sensitivity can be adjusted according to an arbitrary pattern in the pixel array.

[Item 11]
The plurality of unit pixel cells include a first unit pixel cell having a first color color filter and a second unit pixel cell having a second color color filter, and the voltage application circuit is a first unit pixel. The imaging apparatus according to item 10, wherein different voltages are applied between the auxiliary electrode of the cell and the auxiliary electrode of the second unit pixel cell.

According to this configuration, the white balance can be adjusted according to the scene.

[Item 12]
The imaging device according to any one of items 1 to 11, wherein the voltage application circuit switches the voltage applied to the auxiliary electrode in one frame.

According to this configuration, it is possible to make the exposure periods of all the unit pixel cells included in the pixel array uniform.

[Item 13]
The imaging device according to item 12, wherein the voltage application circuit periodically changes the voltage applied to the auxiliary electrodes in one frame.

According to this configuration, it is possible to eliminate the influence of the periodic flicker of the light incident on the image pickup apparatus.

[Item 14]
The imaging device according to items 1 to 13, further comprising a lighting device, wherein the voltage application circuit switches the voltage applied to the auxiliary electrode according to the operation of the lighting device.

According to this configuration, the influence of the light trail of the illumination can be removed.

[Item 15]
The imaging apparatus according to any one of items 12 to 14, further comprising a control line for supplying the upper electrode with a voltage that changes according to the switching of the voltage applied to the auxiliary electrode.

According to this configuration, the sensitivity in the image pickup apparatus can be made closer to 0 by changing the voltage applied to the upper electrode in accordance with the switching of the voltage applied to the auxiliary electrode. Therefore, changes in the voltage applied to the auxiliary electrode and the voltage applied to the upper electrode can be used as the shutter.

[Item 16]
The imaging device according to any one of items 1 to 15, wherein the voltage application circuit applies a different voltage to the auxiliary electrode according to a designated F value.

According to this configuration, it is possible to control the F value without using the aperture mechanism.

[Item 17]
The imaging apparatus according to any one of items 1 to 16, wherein the pixel electrodes include a plurality of sub-pixel electrodes that are spatially separated by being surrounded by auxiliary electrodes.

According to this configuration, it is possible to bring the sensitivity of the image pickup apparatus close to 0 while maintaining the wide incident angle characteristic.

[Item 18]
The plurality of unit pixel cells are a first unit pixel cell in which a first gap is formed between the pixel electrode and the auxiliary electrode, and a second unit pixel cell larger than the first gap between the pixel electrode and the auxiliary electrode. The imaging apparatus according to item 2, wherein the imaging apparatus includes a second unit pixel cell in which a gap is formed.

According to this configuration, pixels having different functions can be arranged in the pixel array.

[Item 19]
The imaging apparatus according to any one of items 1 to 18, wherein the auxiliary electrode includes a plurality of sub-auxiliary electrodes, and each of the plurality of sub-auxiliary electrodes has an electrical connection with a voltage application circuit.

According to this configuration, the region where the holes that can move to the pixel electrode are distributed can be deformed into a shape deviated from the center. Therefore, the unit pixel cell can be used for phase difference detection, and the shape of the region where holes that can move to the pixel electrode are distributed can be flexibly changed by using the sensitivity adjustment voltage.

[Item 20]
Items 1 to 19 include an image processing circuit, the voltage application circuit applies different voltages in at least two frames, and the image processing circuit synthesizes the image signals of at least two frames and outputs the combined image signals. The imaging apparatus according to any one of.

According to this configuration, it is possible to acquire an image of a scene having a large contrast ratio.

[Item 21]
The imaging apparatus according to items 2 and 18, wherein the auxiliary electrodes of the plurality of unit pixel cells are electrically connected to each other.

According to this configuration, the sensitivity adjustment voltage can be collectively applied to the auxiliary electrodes, so that the wiring for driving the auxiliary electrodes can be reduced.

[Item 22]
The imaging device according to item 21, wherein the voltage application circuit changes the voltage in units of two frames.

According to this configuration, an appropriate image signal can be obtained even when shooting with a rolling shutter.

[Item 23]
8. The imaging apparatus according to item 2 and 18, wherein the plurality of unit pixel cells are arranged two-dimensionally in rows and columns, and at least the auxiliary electrodes of the unit pixel cells in each row are electrically connected to each other in each row.

According to this configuration, an appropriate image signal can be obtained for each frame even when shooting with a rolling shutter.

[Item 24]
Auxiliary electrodes of a plurality of unit pixel cells form a group for each n rows (n is an integer of 2 or more), and within each group, the auxiliary electrodes are electrically connected to each other, and each group is electrically connected to each other. The imaging apparatus according to item 23, which is separated from each other.

According to this configuration, since two or more rows of auxiliary electrodes form a group, the number of voltage signals applied to the auxiliary electrodes is 1 / n of the number of rows. Therefore, the circuit scale of the electric power application circuit can be reduced, and the number of wires for driving the auxiliary electrodes can be reduced.

[Item 25]
An illumination system that sequentially emits illumination light from a plurality of different irradiation directions with reference to the subject and illuminates the subject with the illumination light, and an illumination system that is arranged at a position where the illumination light transmitted through the subject is incident, depending on the different irradiation directions. Image processing for forming a high-resolution image of a subject having a resolution higher than that of each of the plurality of images by synthesizing the plurality of images with the imaging device according to any one of items 1 to 22 for acquiring a plurality of different images. An image acquisition device including a unit.

According to this configuration, a high-resolution image can be acquired by synthesizing a plurality of low-resolution images obtained by one imaging device. Further, the resolution can be changed by changing the sensitivity adjustment voltage applied to the auxiliary electrode.

Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. In the following embodiment, an example of detecting a hole as a signal charge among the hole-electron pair generated by photoelectric conversion will be described. The signal charge may be an electron. The present disclosure is not limited to the following embodiments. In addition, changes can be made as appropriate without departing from the scope of the effects of the present disclosure. Furthermore, it is also possible to combine one embodiment with another. In the following description, the same or similar components are designated by the same reference numerals. In addition, duplicate explanations may be omitted.

(First Embodiment)
The imaging apparatus according to this embodiment will be described with reference to FIGS. 1 to 11.

(Structure of Imaging Device 101)
FIG. 1 schematically shows an example of the circuit configuration of the image pickup apparatus 101 according to the first embodiment. The image pickup apparatus 101 includes a plurality of unit pixel cells 14 and peripheral circuits.

The plurality of unit pixel cells 14 are arranged two-dimensionally on the semiconductor substrate, that is, in the row direction and the column direction to form a photosensitive region (pixel region). The image pickup apparatus 101 may be a line sensor, and the plurality of unit pixel cells 14 may be arranged one-dimensionally. As used herein, the row and column directions refer to the directions in which the rows and columns extend, respectively. That is, the vertical direction is the column direction and the horizontal direction is the row direction.

Each unit pixel cell 14 includes a photoelectric conversion unit 10, an amplification transistor 11, a reset transistor 12, and an address transistor (row selection transistor) 13. As will be described in detail below, in the present embodiment, the photoelectric conversion unit 10 includes the pixel electrode 50 and the auxiliary electrode 61, and the signal charge generated by the photoelectric conversion is generated by adjusting the voltage applied to the auxiliary electrode 61. , The amount captured by the pixel electrode 50 is adjusted. That is, the sensitivity of the image pickup apparatus 101 is adjusted.

The image pickup apparatus 101 has a voltage application circuit 60. The voltage application circuit 60 is configured so that at least two different voltages can be simultaneously or selectively applied to the auxiliary electrode 61 during the operation of the image pickup apparatus 101. The voltage application circuit 60 may have a configuration capable of changing the voltage supplied to the auxiliary electrode 61, and the circuit configuration of the voltage application circuit 60 is not limited to a specific circuit configuration. For example, the voltage application circuit 60 may have a configuration for converting a voltage supplied from a voltage source (not shown) into a predetermined voltage. Alternatively, the voltage application circuit 60 itself may be configured to generate a predetermined voltage. Hereinafter, the voltage supplied from the voltage application circuit 60 to the auxiliary electrode 61 is referred to as a sensitivity adjustment voltage. The voltage application circuit 60 supplies the sensitivity adjustment voltage according to the command of the operator who operates the image pickup device 101 and the command of other control circuits included in the image pickup device 101 to the auxiliary electrode 61 via the sensitivity adjustment line 28. .. The voltage application circuit 60 is typically provided outside the photosensitive region as part of a peripheral circuit.

The pixel electrode 50 is connected to the gate electrode of the amplification transistor 11. The signal charge collected by the pixel electrode 50 is stored in the charge storage node 24 located between the pixel electrode 50 and the gate electrode of the amplification transistor 11. In this embodiment, the signal charge is a hole, but the signal charge may be an electron.

The signal charge accumulated in the charge storage node 24 is applied to the gate electrode of the amplification transistor 11 as a voltage corresponding to the amount of the signal charge. The amplification transistor 11 amplifies this voltage. The signal voltage is selectively read by the address transistor 13. The source or drain electrode of the reset transistor 12 is connected to the pixel electrode 50 and resets the signal charge stored in the charge storage node 24. In other words, the reset transistor 12 resets the potentials of the gate electrode and the pixel electrode 50 of the amplification transistor 11.

In order to selectively perform the above-described operation in the plurality of unit pixel cells 14, the image pickup apparatus 101 includes a power supply wiring 21, a vertical signal line 17, an address signal line 26, and a reset signal line 27, and these lines are units. Each is connected to the pixel cell 14. The power supply wiring 21 is connected to the source or drain electrode of the amplification transistor 11, and the vertical signal line 17 is connected to the source or drain electrode of the address transistor 13. The address signal line 26 is connected to the gate electrode of the address transistor 13. The reset signal line 27 is connected to the gate electrode of the reset transistor 12.

Further, the image pickup apparatus 101 includes a photoelectric conversion unit control line 16 for applying a predetermined voltage to the photoelectric conversion unit 10. The voltage supplied to the photoelectric conversion unit 10 via the photoelectric conversion unit control line 16 may be common to all the photoelectric conversion units 10. The voltage supplied to the photoelectric conversion unit 10 via the photoelectric conversion unit control line 16 may be a voltage having a constant magnitude, or may be a voltage that changes with time, as will be described later.

In the configuration illustrated in FIG. 1, the peripheral circuit includes a vertical scanning circuit 15, a horizontal signal reading circuit 20, a plurality of column signal processing circuits 19, a plurality of load circuits 18, and a plurality of inverting amplifiers 22. The vertical scanning circuit 15 is also referred to as a row scanning circuit. The horizontal signal reading circuit 20 is also referred to as a column scanning circuit. The column signal processing circuit 19 is also referred to as a row signal storage circuit. The inverting amplifier 22 is also referred to as a feedback amplifier.

The vertical scanning circuit 15 is connected to the address signal line 26 and the reset signal line 27, selects a plurality of unit pixel cells 14 arranged in each row in row units, reads out the signal voltage, and determines the potential of the pixel electrode 50. Perform a reset. The power supply wiring (source follower power supply) 21 supplies a predetermined power supply voltage to each unit pixel cell 14. The horizontal signal reading circuit 20 is electrically connected to a plurality of column signal processing circuits 19. The column signal processing circuit 19 is electrically connected to the unit pixel cells 14 arranged in each row via the vertical signal lines 17 corresponding to each row. The load circuit 18 is electrically connected to each vertical signal line 17. The load circuit 18 and the amplification transistor 11 form a source follower circuit.

A plurality of inverting amplifiers 22 are provided corresponding to each row. The negative input terminal of the inverting amplifier 22 is connected to the corresponding vertical signal line 17. Further, the output terminal of the inverting amplifier 22 is connected to the unit pixel cell 14 via the feedback line 23 corresponding to each row.

The vertical scanning circuit 15 applies a row selection signal for controlling the on / off of the address transistor 13 to the gate electrode of the address transistor 13 by the address signal line 26. As a result, the line to be read is scanned and selected. A signal voltage is read from the unit pixel cell 14 in the selected row to the vertical signal line 17. Further, the vertical scanning circuit 15 applies a reset signal for controlling on / off of the reset transistor 12 to the gate electrode of the reset transistor 12 via the reset signal line 27. As a result, the row of the unit pixel cell 14 that is the target of the reset operation is selected. The vertical signal line 17 transmits the signal voltage read from the unit pixel cell 14 selected by the vertical scanning circuit 15 to the column signal processing circuit 19.

The column signal processing circuit 19 performs noise suppression signal processing represented by correlated double sampling, analog-to-digital conversion (AD conversion), and the like.

The horizontal signal reading circuit 20 sequentially reads signals from the plurality of column signal processing circuits 19 to the horizontal common signal line 29.

The inverting amplifier 22 is connected to the drain electrode of the reset transistor 12 via the feedback line 23. Therefore, the inverting amplifier 22 receives the output of the address transistor 13 at the negative terminal when the address transistor 13 and the reset transistor 12 are in a conductive state. The inverting amplifier 22 performs a feedback operation so that the gate potential of the amplification transistor 11 becomes a predetermined feedback voltage. At this time, the output voltage value of the inverting amplifier 22 is 0V or a positive voltage in the vicinity of 0V. The feedback voltage means the output voltage of the inverting amplifier 22.

(Device structure of unit pixel cell 14)
FIG. 2 schematically shows a cross section of the device structure of the unit pixel cell 14 in the image pickup apparatus 101 according to the present embodiment.

The unit pixel cell 14 includes a semiconductor substrate 31, a charge detection circuit 25, and a photoelectric conversion unit 10. The semiconductor substrate 31 is, for example, a p-type silicon substrate. The charge detection circuit 25 detects the signal charge captured by the pixel electrode 50 and outputs the signal voltage. The charge detection circuit 25 includes an amplification transistor 11, a reset transistor 12, and an address transistor 13, and is formed on the semiconductor substrate 31.

The amplification transistor 11 is formed on the semiconductor substrate 31, and has n-type impurity regions 41C and 41D that function as drains and sources, respectively, and a gate insulating layer 38B located on the semiconductor substrate 31 and a gate electrode located on the gate insulating layer 38B. Including 39B.

The reset transistor 12 is formed on the semiconductor substrate 31, and has n-type impurity regions 41B and 41A that function as drains and sources, respectively, and a gate insulating layer 38A located on the semiconductor substrate 31 and a gate electrode located on the gate insulating layer 38A. Including 39A.

The address transistor 13 is formed on the semiconductor substrate 31, and has n-type impurity regions 41D and 41E that function as drains and sources, respectively, and a gate insulating layer 38C located on the semiconductor substrate 31 and a gate electrode located on the gate insulating layer 38C. Including 39C. The n-type impurity region 41D is shared by the amplification transistor 11 and the address transistor 13, whereby the amplification transistor 11 and the address transistor 13 are connected in series.

In the semiconductor substrate 31, an element separation region 42 is provided between the adjacent unit pixel cells 14 and between the amplification transistor 11 and the reset transistor 12. The element separation region 42 electrically separates the adjacent unit pixel cells 14. In addition, leakage of signal charge accumulated in the charge storage node is suppressed.

Interlayer insulation layers 43A, 43B and 43C are laminated on the surface of the semiconductor substrate 31. In the interlayer insulating layer 43A, a contact plug 45A connected to the n-type impurity region 41B of the reset transistor 12, a contact plug 45B connected to the gate electrode 39B of the amplification transistor 11, and a contact plug 45A and a contact plug 45B are contained. The wiring 46A to be connected is provided. As a result, the n-type impurity region 41B (drain) of the reset transistor 12 is electrically connected to the gate electrode 39B of the amplification transistor 11.

The photoelectric conversion unit 10 is provided on the interlayer insulating layer 43C. The photoelectric conversion unit 10 includes an upper electrode 52, a photoelectric conversion layer 51, a pixel electrode 50, and an auxiliary electrode 61. The photoelectric conversion layer 51 is sandwiched between the upper electrode 52, the pixel electrode 50, and the auxiliary electrode 61. The pixel electrode 50 and the auxiliary electrode 61 are provided on the interlayer insulating layer 43C. The upper electrode 52 is formed of, for example, a conductive transparent material such as ITO. The pixel electrode 50 and the auxiliary electrode 61 are formed of a metal such as aluminum or copper or polysilicon doped with impurities to impart conductivity.

Although not shown in FIG. 2, the unit pixel cell 14 may have a microlens on the upper electrode 52 of the photoelectric conversion unit 10. It may also have a color filter.

FIG. 3 shows an example of the shapes of the pixel electrode 50 and the auxiliary electrode 61 on the surface of the interlayer insulating layer 43C. FIG. 3 shows nine unit pixel cells arranged in a matrix of 3 rows and 3 columns. The pixel electrode 50 has, for example, a quadrangular shape. In the present embodiment, as shown in FIG. 3, the pixel electrode 50 has a rectangular shape, and the auxiliary electrode 61 has a ring-shaped rectangular shape surrounding the pixel electrode 50. The pixel electrode 50 and the auxiliary electrode 61 are separated by a distance L1 via a gap. In this example, the auxiliary electrodes 61 are integrally formed between the nine unit pixel cells 14 shown, and are electrically connected to each other.

In the present embodiment, the pixel electrode 50 is rectangular, but the pixel electrode 50 may have a polygonal shape of a circle or a pentagon or more. Further, in the present embodiment, the auxiliary electrode 61 surrounds the pixel electrode 50, but the pixel electrode 50 may not be surrounded.

As illustrated in FIG. 2, the pixel electrode 50 includes a plug 47C provided in the interlayer insulating layer 43C, a wiring 46C provided on the interlayer insulating layer 43B, a plug 47B provided in the interlayer insulating layer 43B, and an interlayer. It is connected to the wiring 46A via the wiring 46B provided on the insulating layer 43A and the plug 47A provided in the interlayer insulating layer 43A. Further, the auxiliary electrode 61 is connected to the wiring 49 provided on the interlayer insulating layer 43B via a plug 48 provided in the interlayer insulating layer 43C. These plugs, contact plugs, and wirings are formed of metal such as aluminum and copper, and polysilicon that is doped with impurities to impart conductivity.

In the present embodiment, the image pickup apparatus 101 detects holes as signal charges among the hole-electron pairs generated by the photoelectric conversion in the photoelectric conversion layer 51. The detected signal charge is stored in the charge storage node 24 (see FIG. 1) described above. The charge storage node 24 includes a pixel electrode 50, a gate electrode 39B, an n-type impurity region 41B and plugs 47A, 47B, 47C, contact plugs 45A, 45B and wirings 46C, 46B, 46A (see FIG. 2) connecting them. ..

The photoelectric conversion layer 51 covers the auxiliary electrode 61 and the pixel electrode 50 on the interlayer insulating layer 43C, and is continuously formed over the entire plurality of unit pixel cells 14. The photoelectric conversion layer 51 is formed of, for example, an organic material or amorphous silicon.

Although not shown in FIG. 2, peripheral circuits (here, the vertical scanning circuit 15, the horizontal signal reading circuit 20, the column signal processing circuit 19, the load circuit 18, and the inverting amplifier 22) are also formed on the semiconductor substrate 31.

The image pickup apparatus 101 can be manufactured by using a general semiconductor manufacturing process. In particular, when a silicon substrate is used as the semiconductor substrate 31, the image pickup apparatus 101 can be manufactured by using various silicon semiconductor processes.

(Operation of Imaging Device 101)
Next, an exemplary operation of the image pickup apparatus 101 will be described with reference to FIGS. 1, 2 and 4A to 4D. As described below, when holes are used as signal charges, the holes generated by photoelectric conversion are set to be lower than the potentials of the pixel electrode 50 and the auxiliary electrode 61 to the pixel electrodes. Can be collected on the 50 side.

First, a voltage of about 10 V is applied to the upper electrode 52. Further, the potential of the pixel electrode 50 is reset by turning on the reset transistor 12 and then turning it off. By resetting, the potential of the charge storage node 24 including the pixel electrode 50 is set to the reset voltage (for example, 0V) as an initial value. Further, from the voltage application circuit 60, for example, a first sensitivity adjustment voltage lower than the reset voltage (here, 0 V) is applied to the auxiliary electrode 61. Here, a voltage of -2V is applied to the auxiliary electrode 61 as the first sensitivity adjustment voltage.

In this way, since the potentials of the pixel electrode 50 and the auxiliary electrode 61 are set lower than those of the upper electrode 52, the holes generated by the photoelectric conversion in the photoelectric conversion layer 51 move to the auxiliary electrode 61 and the pixel electrode 50. do. Here, since the voltage of the auxiliary electrode 61 is lower than the voltage of the pixel electrode 50 (the potential difference between the auxiliary electrode 61 and the upper electrode 52 is larger than the potential difference between the pixel electrode 50 and the upper electrode 52). Therefore, the generated holes are more likely to move to the auxiliary electrode 61 than to the pixel electrode 50. As a result, the holes generated in the region 51A (see FIG. 4A) including the portion of the photoelectric conversion layer 51 that overlaps with the pixel electrode 50 mainly moves to the pixel electrode 50 and is detected as a signal charge. .. On the other hand, holes generated in the region 51B (see FIG. 4A) including the portion of the photoelectric conversion layer 51 that overlaps with the auxiliary electrode 61 mainly move to the auxiliary electrode 61. This means that among the light irradiated to the photoelectric conversion layer 51, the light irradiated to the region 51A is detected. That is, the unit pixel cell 14 substantially detects the light incident on the region 51A among the light incident on the imaging surface. The region 51A is a region of the photoelectric conversion layer 51 in which signal charges (here, holes) generated by the photoelectric conversion are mainly collected by the pixel electrodes, and the region 51B is a region of the photoelectric conversion layer 51. This is a region where the signal charge (here, holes) generated by photoelectric conversion is mainly collected by the auxiliary electrode.

FIG. 4B is a plan view of the region 51A as viewed from the pixel electrode 50 and the auxiliary electrode 61 side. In this example, the region 51A has a first area slightly larger than the pixel electrode 50 in a plane parallel to the photoelectric conversion layer 51. As shown in FIG. 4B, the shape and area of the region 51A when viewed from the normal direction of the imaging surface do not necessarily match the shape and area of the pixel electrode 50. Further, as will be described in detail later, the shape and / or area of the region 51A may change depending on the voltage applied to the pixel electrode 50, the auxiliary electrode 61, and the upper electrode 52. The shape and area of the region 51B when viewed from the normal direction of the imaging surface do not necessarily match the shape and area of the auxiliary electrode 61. 4A and 4B schematically show the region 51A, and there is no clear boundary between the region 51A and the region 51B.

A signal charge is accumulated for each frame in a state where the first sensitivity adjustment voltage is applied to the auxiliary electrode 61, and the accumulated charge and the potential of the pixel electrode 50 are reset. Thereby, the light incident on the photoelectric conversion layer 51 can be detected in the region 51A having the first area.

4C and 4D show an example in which the voltage application circuit 60 applies a second sensitivity adjustment voltage higher than the first sensitivity adjustment voltage to the auxiliary electrode 61. For example, the second sensitivity adjustment voltage is 5V.

In this example as well, the holes generated by the photoelectric conversion in the photoelectric conversion layer 51 move to the auxiliary electrode 61 and the pixel electrode 50 in the same manner as when the first sensitivity adjustment voltage is applied. In this example, the second sensitivity adjustment voltage (here 5V) is higher than the reset voltage (here 0V). Therefore, the holes generated in the photoelectric conversion layer 51 are more likely to move toward the pixel electrode 50 than in the auxiliary electrode 61.

Further, in this example, a second sensitivity adjustment voltage higher than the first sensitivity adjustment voltage in the example described with reference to FIGS. 4A and 4B is applied to the auxiliary electrode 61. Therefore, the amount of holes flowing into the auxiliary electrode 61 is smaller than that when the first sensitivity adjusting voltage is applied to the auxiliary electrode 61. That is, the generated holes are more likely to move to the pixel electrode 50. As a result, as schematically shown in FIG. 4C, the region 51C in which the holes that can move to the pixel electrode 50 are distributed is the region 51A when the first sensitivity adjustment voltage is applied to the auxiliary electrode 61 (FIG. 4C). It is larger than 4A). Further, the region 51D in which the holes that can move to the auxiliary electrode 61 are distributed is smaller than the region 51B (see FIG. 4A) when the first sensitivity adjusting voltage is applied to the auxiliary electrode 61.

FIG. 4D is a plan view of the region 51C as viewed from the pixel electrode 50 and the auxiliary electrode 61 side. The region 51C has a second area larger than the first area, for example, in a plane parallel to the photoelectric conversion layer 51.

A signal charge is accumulated for each frame in a state where the second sensitivity adjustment voltage is applied to the auxiliary electrode 61, and the accumulated charge and the potential of the pixel electrode 50 are reset. Thereby, the light incident on the photoelectric conversion layer 51 can be detected in the region 51C having the second area.

As described above, when the first sensitivity adjustment voltage is applied to the auxiliary electrode 61, the region 51A in which the signal charge is captured by the pixel electrode 50 is relatively small, and when the second sensitivity adjustment voltage is applied, the region 51A is relatively small. The region 51C in which the signal charge is captured by the pixel electrode 50 is relatively large. That is, when the first sensitivity adjustment voltage is applied to the auxiliary electrode 61, the sensitivity of the image pickup apparatus 101 is relatively low, and when the second sensitivity adjustment voltage is applied, the sensitivity is relatively high. By changing the sensitivity adjustment voltage applied to the auxiliary electrode 61 in this way, the sensitivity of the image pickup apparatus 101 can be changed. The larger the distance L1 (see FIGS. 4A and 4C) between the pixel electrode 50 and the auxiliary electrode 61, the more the signal charge is captured by the pixel electrode 50, which can be adjusted by changing the sensitivity adjustment voltage (here). Then, the range of change in the size of the regions 51A and 51C) becomes large.

FIG. 5 schematically shows the relationship between the sensitivity adjustment voltage applied to the auxiliary electrode and the sensitivity of the image pickup apparatus 101 when the signal charge is a hole. As shown in FIG. 5, when the sensitivity adjustment voltage applied to the auxiliary electrode is changed, the sensitivity also changes. For example, when the sensitivity adjustment voltage is increased, the sensitivity increases. As described above, according to the present embodiment, an imaging device having variable sensitivity is realized.

In the above embodiment, the signal charge is a hole, but the signal charge may be an electron. In this case, a voltage higher than that of the upper electrode 52 is applied to the pixel electrode 50 and the auxiliary electrode 61, and the electrons generated by the photoelectric conversion are moved to the pixel electrode 50 and the auxiliary electrode 61. When the signal charge is an electron, the smaller the sensitivity adjustment voltage applied to the auxiliary electrode, the easier it is for the electron to flow to the pixel electrode, and the higher the sensitivity of the image pickup device. On the other hand, when the sensitivity adjustment voltage applied to the auxiliary electrode is relatively high, electrons easily flow to the auxiliary electrode, and the sensitivity of the image pickup apparatus becomes low.

In this way, by switching the sensitivity adjustment voltage applied to the auxiliary electrode 61 from the voltage application circuit 60, it is possible to change the sensitivity of the image pickup apparatus 101 according to the sensitivity adjustment voltage to be applied. When holes are used as signal charges, if the potential difference between the upper electrode 52 and the auxiliary electrode 61 is larger than the potential difference between the upper electrode 52 and the pixel electrode 50, the sensitivity of the image pickup apparatus becomes relatively low. On the other hand, when the potential difference between the upper electrode 52 and the auxiliary electrode 61 is smaller than the potential difference between the upper electrode 52 and the pixel electrode 50, the sensitivity of the image pickup apparatus becomes relatively high. This relationship also holds when electrons are used as signal charges. For example, if the potential difference between the upper electrode 52 and the auxiliary electrode 61 is larger than the potential difference between the upper electrode 52 and the pixel electrode 50, the sensitivity of the image pickup apparatus becomes relatively low.

Further, in the example described with reference to FIGS. 4A to 4D described above, the sensitivity adjustment voltage applied to the auxiliary electrode 61 is changed between a value higher and a value lower than the reset voltage of the pixel electrode 50. However, the sensitivity of the image pickup apparatus 101 can be changed even if the sensitivity adjustment voltage applied to the auxiliary electrode 61 is changed in a range higher or lower than the reset voltage of the pixel electrode 50. For example, when holes are used as signal charges and the sensitivity adjustment voltage is changed in a range lower than the reset voltage of the pixel electrode 50, the larger the potential difference between the pixel electrode 50 and the auxiliary electrode 61, the larger the potential difference. , The degree of decrease in sensitivity of the imaging device increases.

Next, with reference to FIGS. 6A to 6D, the value of the sensitivity adjustment voltage applied to the auxiliary electrode 61 and the features of the image pickup apparatus 101 realized by the value will be further described.

First, a case where the reset voltage of the pixel electrode 50 is Vr and the signal charge is a hole will be described. FIG. 6A shows a region where the signal charge is captured by the pixel electrode 50 when the sensitivity adjustment voltages V1 and V2 satisfying V1 <Vr <V2 are applied to the auxiliary electrode 61, as viewed from the pixel electrode 50 and the auxiliary electrode 61 side. It is a plan view. In FIG. 6A, in the regions 51A1, 51Ar, and 51A2, signal charges (holes in this case) are captured by the pixel electrodes 50 when the sensitivity adjusting voltages of V1, Vr, and V2 are applied to the auxiliary electrodes 61, respectively. The regions are shown schematically. When the reset voltage Vr is applied to the auxiliary electrode 61, the initialized pixel electrode 50 and the auxiliary electrode 61 have the same potential. Therefore, the boundary of the region 51Ar when the reset voltage Vr is applied to the auxiliary electrode 61 is located substantially in the middle between the pixel electrode 50 and the auxiliary electrode 61.

When the signal charge is a hole, the smaller the voltage applied to the auxiliary electrode 61, the easier it is for the auxiliary electrode 61 to capture the hole, which is the signal charge, and the smaller the region where the signal charge is captured by the pixel electrode 50. Become. Therefore, if a sensitivity adjustment voltage V1 smaller than Vr is applied based on the case where the sensitivity adjustment voltage is set to Vr, the region 51A1 can be made smaller than the region 51Ar when Vr is applied. Further, if a sensitivity adjustment voltage V2 larger than Vr is applied, the region 51A2 can be made larger than the region 51Ar when Vr is applied. In this way, by selectively applying the sensitivity adjustment voltage V1 smaller than the reset voltage Vr and the sensitivity adjustment voltage V2 larger than the reset voltage Vr, the size of the region where holes are captured by the pixel electrode 50 can be widely changed. It is possible to realize an image pickup device 101 having a wide adjustment range of sensitivity.

FIG. 6B shows a region where the signal charge is captured by the pixel electrode 50 when the sensitivity adjustment voltages V1 and V2 satisfying Vr <V1 <V2 are applied to the auxiliary electrode 61, as viewed from the pixel electrode 50 and the auxiliary electrode 61 side. It is a plan view. If a sensitivity adjustment voltage V1 larger than Vr is applied based on the case where the sensitivity adjustment voltage is set to Vr, the region 51A1 can be made larger than the region 51Ar when Vr is applied. Further, if a sensitivity adjustment voltage V2 larger than V1 is applied, the region 51A2 can be made larger than the region 51A1 when V1 is applied. Therefore, by applying the sensitivity adjustment voltage V1 satisfying the relationship of Vr <V1 <V2 to the auxiliary electrode 61, it is possible to secure good sensitivity to some extent while suppressing color mixing between unit pixel cells. Further, high sensitivity can be realized by applying the sensitivity adjustment voltage V2 to the auxiliary electrode 61.

FIG. 6C is a plan view of the region where the signal charge is captured by the pixel electrode 50 when the sensitivity adjustment voltage V1 satisfying V1 <0 is applied to the auxiliary electrode 61, as viewed from the pixel electrode 50 and the auxiliary electrode 61 side. .. By setting the sensitivity adjustment voltage V1 to a negative value, many holes are captured by the auxiliary electrode 61, so that the region 51A1 becomes smaller. As a result, it is possible to realize an image pickup apparatus in which the sensitivity is lowered and overexposure is less likely to occur even in a bright environment. When a negative voltage is used as the voltage for driving (switching ON and OFF) the transistors (reset transistor 12, address transistor 13, etc.) provided in the pixels, the sensitivity adjustment voltage is applied to the auxiliary electrode 61. Can also be used as. For example, when the reset transistor 12 is turned ON or OFF by applying a negative voltage to the gate voltage of the reset transistor 12, the gate voltage generation circuit can be used as the voltage application circuit 60. As a result, the scale of the peripheral circuit can be reduced and the configuration of the peripheral circuit can be simplified.

When the signal charge is an electron, the magnitude relationship of V1, V2, and Vr when the signal charge is a hole may be reversed. For example, sensitivity adjustment voltages V1 and V2 that satisfy V1 <V2 <Vr may be applied to the auxiliary electrode 61. FIG. 6D shows a region in which the signal charge (here, the electron) is captured by the pixel electrode 50 when the signal charge is an electron and the sensitivity adjustment voltages V1 and V2 satisfying V1 <V2 <Vr are applied to the auxiliary electrode 61. Is a plan view seen from the side of the pixel electrode 50 and the auxiliary electrode 61.

When the signal charge is an electron, the lower the voltage applied to the auxiliary electrode 61, the more difficult it is for the signal charge (here, the electron) to be captured by the auxiliary electrode 61, and the larger the region where the signal charge is captured by the pixel electrode 50. Become. Therefore, if a sensitivity adjustment voltage V2 lower than Vr is applied, the region 51A2 can be made larger than the region 51Ar when Vr is applied. Further, if a sensitivity adjustment voltage V1 lower than V2 is applied, the region 51A1 can be made larger than the region 51A2 when V2 is applied. Therefore, by applying the sensitivity adjustment voltage V2 satisfying the relationship of V1 <V2 <Vr to the auxiliary electrode 61, it is possible to secure good sensitivity to some extent while suppressing color mixing between unit pixel cells. Further, high sensitivity can be realized by applying the sensitivity adjustment voltage V1 to the auxiliary electrode 61.

Next, an exemplary driving method of the image pickup apparatus 101 will be described with reference to FIGS. 1 and 7. FIG. 7 is a timing chart showing an example of the timing of application and exposure of the sensitivity adjustment voltage when the sensitivity adjustment voltage is changed in the image pickup apparatus 101.

In FIG. 7, RST1, RST2, ..., RSTn are gate voltages applied to the gate electrodes of the reset transistor 12 constituting the first, second, ..., nth rows, respectively (hereinafter, reset gate). (Sometimes called voltage) indicates the timing. As described with reference to FIG. 1, the image pickup apparatus 101 performs exposure and signal reading line by line (rolling shutter), for example. Therefore, by applying the reset gate voltage, the charge storage node 24 in the unit pixel cell 14 of each row is sequentially reset during the period of one frame. In each row of the pixel array, the period from the application of the reset gate voltage to the application of the next reset gate voltage corresponds to the exposure time.

In the example shown in FIG. 7, the sensitivity adjustment voltage SSV applied to the auxiliary electrode 61 is changed at the start timing of the second frame. As described with reference to FIG. 3, here, the auxiliary electrode 61 is continuously formed over the plurality of unit pixel cells 14. That is, in the configuration illustrated in FIG. 3, the sensitivity adjustment voltage applied to the auxiliary electrode 61 is controlled at the same timing as a whole, not for each row. While the sensitivity adjustment voltage is controlled at the same timing in the entire pixel array, the timing of the exposure start of each row of pixels is deviated from row to row, as can be seen from FIG. Therefore, no matter when the sensitivity adjustment voltage applied to the auxiliary electrode 61 is changed, the sensitivity adjustment voltage changes during the exposure time. In the frame in which the sensitivity adjustment voltage is changed (here, the second frame), the sensitivity is different for each row, and the sensitivity adjustment voltage changes in the middle of the exposure period, so the correct sensitivity corresponding to the applied sensitivity adjustment voltage is used. , The incident light cannot be detected. Therefore, the image data captured in the second frame in which the sensitivity adjustment voltage is changed is discarded. In the next third frame, since the changed sensitivity adjustment voltage is applied in every row from the start of exposure, it is possible to detect the incident light with the correct sensitivity in all the rows.

In this way, by changing the sensitivity adjustment voltage applied to the auxiliary electrode 61 in units of at least two frames, it is possible to acquire an image in which the sensitivity is changed in units of frames. Therefore, according to the present embodiment, the sensitivity of the image pickup apparatus can be changed on a frame-by-frame basis by changing the value of the sensitivity adjustment voltage supplied from the voltage application circuit. Therefore, it is possible to realize an image pickup apparatus capable of taking a picture with high image quality even in various environments where the brightness changes greatly.

Further, since the auxiliary electrodes 61 of each unit pixel cell 14 are connected to each other and the sensitivity adjustment voltage can be collectively applied to the auxiliary electrodes 61, the wiring for driving the auxiliary electrodes can be reduced.

Japanese Patent Application Laid-Open No. 2008-112907 and International Publication No. 2013/001809 disclose that a shield electrode is used to prevent color mixing. In such a technique, in order to obtain these technical effects, it is preferable that the sensitivity adjustment voltage applied to the shield electrode is constant. Therefore, the technique of the present disclosure of adjusting the sensitivity by the sensitivity adjusting voltage applied to the auxiliary electrode is based on a completely different idea from the techniques disclosed in these documents.

(Modified example of the first embodiment)
In the operation described with reference to FIG. 7, the sensitivity adjustment voltage applied to the auxiliary electrode 61 is changed in units of 2 frames. However, the switching of the sensitivity adjustment voltage is not limited to the unit of two frames. As described below, it is also possible to switch the sensitivity adjustment voltage in units of one frame.

FIG. 8 is a timing chart showing another example of timing of application of sensitivity adjustment voltage, exposure, and signal readout. In the example shown in FIG. 8, the voltage application circuit 60 switches the sensitivity adjustment voltage SSV from V0 to Vs during one frame, and further switches the sensitivity adjustment voltage SSV to V0 again after a lapse of a certain period of time.

In this example, the voltage V0 is a voltage sufficiently low enough to make the sensitivity of the image pickup apparatus 101 almost zero. That is, in a state where the voltage V0 is applied to the auxiliary electrode 61, most of the signal charges (holes in this case) generated in the photoelectric conversion layer 51 are captured by the auxiliary electrode 61. In other words, when the voltage V0 is applied to the auxiliary electrode 61, the region where the signal charge is captured by the pixel electrode 50 (see, for example, the region 51A shown in FIGS. 4A and 4B) is sufficient. It is small and the signal charge captured by the pixel electrode 50 is small. That is, by applying the voltage V0 to the auxiliary electrode 61, it is possible to realize a state as if the photosensitive region is shielded from light. On the other hand, by applying a voltage Vs that is appropriately higher than the voltage V0 to the auxiliary electrode 61, the region where the signal charge is captured by the pixel electrode 50 is appropriately expanded, and the image pickup device 101 has the sensitivity required for photographing. be able to.

In the example shown in FIG. 8, the voltage Vs is applied to the auxiliary electrode 61 during a certain period within one frame, and the voltage V0 is applied during the other period. Therefore, the collection of the signal charge by the pixel electrode 50 is executed except for the period when the voltage V0 is applied to the auxiliary electrode 61, which has a sensitivity of almost 0. That is, the period during which the voltage Vs is applied to the auxiliary electrode 61 in one frame contributes to the accumulation of signal charges as an effective exposure time.

As described above, according to the present embodiment, the effective exposure time can be adjusted by the period in which the voltage Vs is applied to the auxiliary electrode 61. As shown in FIG. 8, this effective exposure time can be common to all unit pixel cells 14. Therefore, it is possible to make the exposure periods of all the unit pixel cells included in the pixel array uniform. That is, by changing the sensitivity adjustment voltage within one frame, it is possible to realize the same function as the so-called global shutter without separately providing a capacitance element or the like for accumulating the signal charge in the pixel.

FIG. 9 is a timing chart showing still another example of the timing of application of the sensitivity adjustment voltage, exposure, and signal readout. As described with reference to FIG. 8, by applying a voltage V0 of an appropriate magnitude to the auxiliary electrode 61, the sensitivity of the image pickup apparatus 101 can be reduced to substantially 0. That is, the sensitivity adjustment voltage applied to the auxiliary electrode 61 can be used instead of the shutter. Similar to the example described with reference to FIG. 8, in this example as well, the accumulation of signal charges is performed during the period when the voltage Vs is applied to the auxiliary electrode 61. The period in which the voltage V0 is applied to the auxiliary electrode 61 does not effectively contribute to image acquisition.

In the example shown in FIG. 9, the voltage application circuit 60 periodically switches the sensitivity adjustment voltage SSV between V0 and Vs during one frame. Therefore, the effective exposure period and the non-exposure period are periodically repeated. For example, when shooting under a lighting fixture having periodic flicker, the influence of the periodic flicker of the lighting fixture can be canceled by periodically changing the voltage applied to the auxiliary electrode 61.

FIG. 10 is a timing chart showing still another example of the timing of application of the sensitivity adjustment voltage, exposure, and signal readout. FIG. 10 is a diagram for explaining an example of operation in an image pickup apparatus having a flash (see, for example, FIG. 14B described later). In FIG. 10, the flash emission timing is shown along with the change in the sensitivity adjustment voltage SSV and the change in the reset gate voltage of each row of the pixel array.

In the example shown in FIG. 10, the flash operation is executed in the second frame. The voltage application circuit 60 changes the sensitivity adjustment voltage SSV in synchronization with the flash. Specifically, the voltage application circuit 60 applies a voltage Vs to the auxiliary electrode 61 during the flash extinguishing period, and applies a voltage Vt lower than the voltage Vs to the auxiliary electrode 61 during the flash lighting period. That is, an operation is performed in which the sensitivity of the image pickup apparatus is lowered during the flash lighting period.

In this way, the sensitivity adjustment voltage SSV may be changed so that the sensitivity of the image pickup apparatus temporarily decreases during the flash lighting period. By temporarily reducing the sensitivity of the image pickup apparatus during the flash lighting period, the occurrence of overexposure can be suppressed. Further, the influence of the light trail caused by the movement of the bright spot such as the reflection of the flash can be removed. Instead of the voltage Vt, the above-mentioned voltage V0 that makes the sensitivity of the image pickup apparatus substantially 0 may be applied to the auxiliary electrode 61.

FIG. 11 is a timing chart showing still another example of the timing of application of the sensitivity adjustment voltage, exposure, and signal readout. FIG. 11 shows a change in the voltage applied to the upper electrode 52 along with a change in the sensitivity adjustment voltage SSV and a change in the reset gate voltage of each row of the pixel array. As described below, the magnitude of the voltage applied to the upper electrode 52 may be changed according to the change in the sensitivity adjustment voltage SSV.

Here, similarly to the example described with reference to FIG. 8, a period in which the voltage V0 is applied to the auxiliary electrode 61 and a period in which the voltage Vs is applied are provided in one frame. The sensitivity during the period when the voltage V0 is applied to the auxiliary electrode 61 is lower than the sensitivity during the period when the voltage Vs is applied to the auxiliary electrode 61. However, it may not be possible to sufficiently reduce the sensitivity of the image pickup apparatus simply by adjusting the sensitivity adjustment voltage.

In the example shown in FIG. 11, the voltage applied to the upper electrode 52 is changed in accordance with the change in the sensitivity adjustment voltage via the photoelectric conversion unit control line 16 (see FIG. 1). Specifically, during the period in which the voltage Vs is applied to the auxiliary electrode 61 (effective exposure period), a predetermined voltage Vp is applied to the upper electrode 52, and the voltage V0 is applied to the auxiliary electrode 61. Apply a voltage Vq lower than the voltage Vp to the upper electrode 52. In this way, by lowering the potential of the upper electrode 52 during a period other than the effective exposure period, the sensitivity of the image pickup apparatus 101 can be further lowered. By adjusting the voltage of the upper electrode 52 in addition to the sensitivity adjustment voltage, a more effective electronic shutter operation can be performed. The voltage applied to the upper electrode 52 may be supplied from the voltage application circuit 60 or the vertical scanning circuit 15 via the photoelectric conversion unit control line 16.

(Second Embodiment)
Next, the imaging apparatus according to the present embodiment will be described with reference to FIGS. 12A to 13B.

The image pickup apparatus of the present embodiment is different from the image pickup apparatus of the first embodiment in that the auxiliary electrodes are electrically separated for each row. Since the configuration other than the auxiliary electrode and the voltage application circuit can be the same as that of the first embodiment, the auxiliary electrode and the voltage application circuit will be mainly described.

FIG. 12A schematically shows an example of the planar structure of the auxiliary electrode in the image pickup apparatus of this embodiment. Imaging apparatus of the present embodiment comprises the auxiliary electrode lines 61 ₁ to the auxiliary electrode 61 is electrically connected to each row of the unit pixel cells 14, 61 _2, ..., and 61 _n. Auxiliary electrode lines 61 _1, 61 _2,
..., 61 _n are electrically separated from each other.

As shown, the auxiliary electrode lines 61 _1, 61 _2, ..., each of the 61 _n, the voltage application circuit 6
Has a connection with 0A. Voltage applying circuit 60A, the auxiliary electrode lines 61 _1, 61 _2, ..., separately for each of the 61 _n, and is configured to provide at least two sensitivity adjustment voltage. In the following example described with reference to FIG. 12A, switching between the two sensitivity adjustment voltages is executed at different timings for each auxiliary electrode row.

FIG. 12B shows an example of a timing chart showing the timing of application of the sensitivity adjustment voltage, exposure, and signal readout in the configuration shown in FIG. 12A. In Figure 12B, SSV1, SSV2, ..., SSVN, respectively, the auxiliary electrode lines 61 _1, 61 _2, ..., a timing of change of the sensitivity adjusting voltage applied to 61 _n.

The image pickup apparatus of this embodiment can change the sensitivity adjustment voltage for each row of the pixel array at different timings. Therefore, as shown in FIG. 12B, the sensitivity adjustment voltage can be changed in each row of the pixel array according to, for example, the timing of switching the reset gate voltage from the high level to the low level. As a result, the sensitivity adjustment voltage in each frame can be made constant in each row of the pixel. That is, the sensitivity can be changed on a frame-by-frame basis for each line.

According to the image pickup apparatus of the present embodiment, since it is possible to avoid a change in the sensitivity adjustment voltage during the exposure period, continuous frame shooting is possible without causing frames that cannot be shot correctly, and the sensitivity is in frame units. It is possible to adjust. For example, since the image pickup apparatus of the present embodiment can adjust the sensitivity in frame units, it responds to the change in brightness at high speed and adjusts the sensitivity even in a shooting environment where the brightness changes rapidly. It is possible.

The imaging device of the present embodiment can also be applied to a driving method in which the exposure time is adjusted by an electronic shutter. For example, as shown in FIG. 12C, each row of the pixel array is further provided with a period in which the reset gate voltage is set to a high level for each frame and the reset gate voltage is set to a high level again during the frame period. Thereby, one frame period can be divided into a non-exposure time and an exposure time. The exposure time can be changed by changing the timing at which the reset gate voltage is brought to a high level again during the frame period.

When applying such control of the exposure time by the electronic shutter, the sensitivity adjustment voltage may be changed to the non-exposure time as shown in FIG. 12C. As a result, the sensitivity adjustment voltage does not change in the middle of the exposure period in each row, and a constant sensitivity adjustment voltage can be applied over the entire exposure period. Therefore, an imaging device capable of continuous frame shooting and adjusting the sensitivity in frame units is realized without generating frames that cannot be shot correctly. Further, the exposure time can be adjusted by the electronic shutter.

In the example described with reference to FIGS. 12A to 12C, the auxiliary electrodes of the unit pixel cell 14 form an auxiliary electrode row by being electrically connected to each other in each row, and each auxiliary electrode row is electrically connected. Is separated. However, the auxiliary electrodes may form a group in units of n rows (n is an integer of 2 or more) instead of one row at a time. Within each group, the auxiliary electrodes may be electrically connected to each other and each group may be electrically separated from each other.

FIG. 13A schematically shows the planar structure of the auxiliary electrodes forming one group in units of two rows of the pixel array. In the configuration illustrated in FIG. 13A, for example, the auxiliary electrode of the unit pixel cell 14 included in the first row of the pixel array and the auxiliary electrode of the unit pixel cell 14 included in the second row form one group. ing. As shown, the plurality of auxiliary electrodes belonging to this group are electrically connected to each other by being integrally formed. In the configuration illustrated in FIG. 13A, the auxiliary electrode, the auxiliary electrode lines 61 ₁ shown in FIG. 12A and the auxiliary electrode lines 61 ₂ may be said to include an integrally formed structure.

As shown in the figure, each of the groups of two rows of the pixel array is connected to the voltage application circuit 60B. The voltage application circuit 60B is configured to be able to individually supply at least two sensitivity adjustment voltages to each group.

FIG. 13B is a timing chart showing an example of the timing of application of the sensitivity adjustment voltage, exposure, and signal readout when the sensitivity adjustment voltage is changed in the image pickup apparatus having the electrode structure shown in FIG. 13A. In this example, the sensitivity adjustment voltage switching is performed every two lines. As shown in FIG. 13B, the timing of the change in the sensitivity adjustment voltage is the same in each set of SSV1 and SSV2, SSV3 and SSV4, and the like. Further, as can be seen by referring to the changes in the set of RST1 and RST2, the set of RST3 and RST4, etc., the reset gate voltage is also switched every two rows. Therefore, the electronic shutter is also controlled in units of two rows.

In addition, in FIG. 13B, the change in the voltage of the auxiliary electrode row corresponding to each row of the pixel array such as SSV1 and SSV2 is shown separately, but in this example, the two auxiliary electrode rows form one group. In addition, the auxiliary electrodes 61 are electrically connected to each other in each group. Therefore, in practice, SSV1 and SSV2 may be one common signal. The reset gate voltage signal supplied to the unit pixel cell 14 corresponding to the auxiliary electrode row belonging to the same group such as RST1 and RST2 may also be common.

According to this type of imaging device, the change in the sensitivity adjustment voltage to be supplied to the pixel array can be shared in units of n rows, so that the number of signals for adjusting the sensitivity can be reduced to 1 / n of the number of rows. .. Therefore, the circuit scale of the electric power application circuit 60B can be reduced, the circuit can be simplified, and the number of wires for driving the auxiliary electrode 61 can be reduced.

(Third Embodiment)
The imaging apparatus according to this embodiment will be described with reference to FIG. 14A.

The image pickup apparatus of the present embodiment is different from the image pickup apparatus of the first embodiment in that it further includes a light amount detection circuit. Since the configuration other than the light amount detection circuit can be the same as that of the first embodiment, the light amount detection circuit will be mainly described.

FIG. 14A schematically shows an example of the circuit configuration of the image pickup apparatus 103 of the present embodiment. The image pickup device 103 further includes a light amount detection circuit 70 in addition to the configuration of the image pickup device 101 of the first embodiment. The light amount detection circuit 70 includes a photodetector element and detects the amount of light per unit area incident on the photoelectric conversion unit 10. The amount of light per unit area may be illuminance.

The light amount detection circuit 70 outputs a detection signal regarding the amount of light per unit area to the voltage application circuit 60C. The voltage application circuit 60C applies a sensitivity adjustment voltage according to the detection signal to the auxiliary electrode 61 of each unit pixel cell 14. For example, when the signal charge is a hole and the detection signal is large due to a large amount of light incident per unit area of the photoelectric conversion layer, the voltage application circuit 60C applies a relatively low sensitivity adjustment voltage to the unit pixel cell 14. Supply to. By applying a relatively low voltage to the auxiliary electrode 61, the sensitivity of the image pickup apparatus 103 is lowered as described in the first embodiment. Therefore, it is possible to obtain a high-quality image in which overexposure is suppressed.

Further, when the detection signal is small due to the small amount of light incident per unit area of the photoelectric conversion layer, the voltage application circuit 60C supplies a relatively high sensitivity adjustment voltage to the unit pixel cell 14. By applying a relatively high sensitivity adjustment voltage to the auxiliary electrode 61, the sensitivity of the image pickup apparatus 103 is increased. Therefore, it is possible to obtain a high-quality image in which blackout is suppressed.

As described above, according to the image pickup apparatus of the present embodiment, the sensitivity is automatically adjusted, and it is possible to take a picture with an appropriate sensitivity according to the brightness of the environment.

(Modified example of the third embodiment)
FIG. 14B shows an example of another configuration of the image pickup apparatus according to the third embodiment. The imaging device 103A shown in FIG. 14B has a flash 72. In the configuration illustrated in FIG. 14B, as described with reference to FIG. 10, an operation may be executed in which the sensitivity of the image pickup apparatus 103A is temporarily lowered in accordance with the flash emission timing. For example, the voltage application circuit 60C may supply the sensitivity adjustment voltage to the unit pixel cell 14 so that the sensitivity of the image pickup apparatus 103A is temporarily lowered in accordance with the flash emission timing.

FIG. 15 shows an example of still another configuration of the image pickup apparatus according to the third embodiment. The image pickup apparatus 103B shown in FIG. 15 has an input interface 74. In the configuration illustrated in FIG. 15, the input interface 74 receives input from the user. Here, the input interface 74 is configured to accept at least the input of the F value from the user. Examples of the input interface 74 are buttons, dials, touch screens and the like.

For example, as described above with reference to FIGS. 4B and 4D, according to the embodiment of the present disclosure, the signal charge is captured by the pixel electrode 50 by changing the sensitivity adjustment voltage applied to the auxiliary electrode 61. The size of the region (see, for example, region 51A shown in FIG. 4B and region 51C shown in FIG. 4D) can be varied. That is, it is possible to change the size of the region contributing to the generation of the signal charge in each unit pixel cell 14 according to the value of the sensitivity adjustment voltage. As can be seen by comparing FIGS. 4B and 4D, the region 51A shown in FIG. 4B is smaller than the region 51C shown in FIG. 4D, and the boundary of the region 51A is located inside the boundary of the region 51C. As shown in FIG. 4B, when the region (for example, region 51A) in which the signal charge is captured by the pixel electrode 50 formed in the photoelectric conversion layer is relatively small, and therefore the sensitivity of the image pickup apparatus is adjusted to be low, the region is not widened. Light rays incident at a position away from the center of the region do not contribute to the formation of the image. That is, the state in which the region where the signal charge is captured by the pixel electrode 50 is reduced corresponds to the state in which the aperture of the camera is reduced. This means that the F value can be controlled by changing the size of the region where the signal charge is captured by the pixel electrode 50 by using the sensitivity adjustment voltage.

See FIG. In the configuration illustrated in FIG. 15, the voltage application circuit 60D supplies the pixel array with a sensitivity adjustment voltage corresponding to the input from the input interface 74. For example, when the first value is specified as the F value via the input interface 74, the voltage application circuit 60D applies the first sensitivity adjustment voltage (for example, -2V) to the auxiliary electrode 61. When a second value smaller than the first value is specified as the F value via the input interface 74, the voltage application circuit 60D applies a second sensitivity adjusting voltage (for example, 5V) to the auxiliary electrode 61. By applying the second sensitivity adjustment voltage to the auxiliary electrode 61, the region in which the signal charge is captured by the pixel electrode 50 is expanded as compared with the case where the first sensitivity adjustment voltage is applied to the auxiliary electrode 61. By expanding the area where the signal charge is captured by the pixel electrode 50, a state similar to the state in which the aperture of the camera is increased is realized.

As described above, according to the embodiment of the present disclosure, the F value can be controlled by adjusting the sensitivity adjustment voltage. Since it is not necessary to provide a diaphragm mechanism for controlling the F value using the sensitivity adjustment voltage, it is possible to continuously change the F value. In this example, the F value is controlled by changing the sensitivity adjustment voltage based on the user's operation on the input interface 74. However, the control of the F value is not limited to the above example. For example, the value of the sensitivity adjustment voltage may be determined based on the detection result of the light amount detection circuit, and the F value may be automatically controlled.

FIG. 16 shows an example of arrangement of pixel electrodes and auxiliary electrodes in an image pickup apparatus having an input interface 74. FIG. 16 is an example of extracting nine of a plurality of unit pixel cells in a pixel array.

The pixel electrode 50B in each of the unit pixel cells 14B shown in FIG. 16 includes nine sub-pixel electrodes 50a to 50i. The sub-pixel electrodes 50a to 50i are electrically connected to each other by being connected to the gate electrode 39B (see FIG. 2) of the same amplification transistor 11. That is, during the operation of the image pickup apparatus, the potentials of the sub-pixel electrodes 50a to 50i in one unit pixel cell 14B are common. In the imaging apparatus of the present disclosure, which unit pixel cell the pixel electrode of interest belongs to is determined by which amplification transistor the gate electrode is connected to. That is, if one pixel electrode is connected to the gate electrode of the first amplification transistor and another pixel electrode is connected to the gate electrode of the second amplification transistor, the two pixel electrodes will be connected to each other. Distinguished as electrodes belonging to different unit pixel cells.

In this example, the sub-pixel electrodes 50a to 50i are spatially separated, and the auxiliary electrodes 61B surround each of the sub-pixel electrodes 50a to 50i. Further, in this example, the auxiliary electrodes 61B are electrically connected to each other between the plurality of unit pixel cells 14B. Of course, the number, shape, and arrangement of the sub-pixel electrodes in the unit pixel cell 14B are not limited to the example shown in FIG. The shape of the auxiliary electrode 61B is also not limited to the example shown in FIG.

As described above, according to the embodiment of the present disclosure, it is possible to change the size of the region in the photoelectric conversion layer 51 in which the signal charge is captured by the pixel electrode 50 by changing the sensitivity adjustment voltage. Is. As the size of the region where the signal charge is captured by the pixel electrode 50 changes, the sensitivity of the image pickup apparatus changes. That is, it is possible to control the sensitivity of the image pickup apparatus by using the sensitivity adjustment voltage.

However, if the size of the region where the signal charge is captured by the pixel electrode 50 changes extremely due to the change in the sensitivity adjustment voltage, the unintended F value changes due to the change in the size of the region. Changes can occur. This is because a change in the size of the region in the photoelectric conversion layer 51 in which the signal charge is captured by the pixel electrode 50 produces the same effect as changing the size of the aperture of the camera.

In the configuration illustrated in FIG. 16, a plurality of sub-pixel electrodes 50a to 50i spatially separated by the auxiliary electrode 61B are provided in the unit pixel cell 14B. Thereby, a plurality of sub-regions separated from each other can be formed in a single unit pixel cell 14B corresponding to the sub-pixel electrodes 50a to 50i. These sub-regions are regions in which signal charges are captured by the sub-pixel electrodes 50a to 50i. When the sensitivity adjustment voltage is changed, the size of each of the plurality of sub-regions formed in the unit pixel cell 14B changes. Therefore, the sensitivity of the image pickup apparatus changes as the sensitivity adjustment voltage changes.

At this time, the change in magnitude in each of the plurality of sub-regions due to the change in the sensitivity adjustment voltage is generally caused by the signal charge caused by the pixel electrode 50 in the configuration in which a single pixel electrode is provided in the unit pixel cell 14. It is smaller than the change in size of the captured region (see, for example, region 51A shown in FIG. 4B). That is, by forming a plurality of sub-regions in each of the unit pixel cells 14B, the signal charge is captured while obtaining the effect of sensitivity adjustment by changing the sensitivity adjustment voltage, and the size in each of the plurality of sub-regions is large. The range of change can be reduced. Therefore, it is possible to suppress an unintended change in the F value while maintaining the effect of the sensitivity adjustment by changing the sensitivity adjustment voltage.

It should be noted that the signal charge by the pixel electrode 50 can also be reduced by reducing the distance L1 (see, for example, FIG. 3) between the pixel electrode 50 and the auxiliary electrode 61 without dividing the pixel electrode 50 in each unit pixel cell 14. It is possible to reduce the range of change in the size of the area in which the is captured. However, it is difficult to secure a sufficient range as a range of change in the size of the region in which the signal charge is captured by the pixel electrode 50 in each unit pixel cell 14 by simply reducing the distance L1. Therefore, it is difficult to obtain a sufficient sensitivity adjustment effect.

(Fourth Embodiment)
The imaging apparatus according to this embodiment will be described with reference to FIG.

The image pickup apparatus of the present embodiment is different from the image pickup apparatus of the first embodiment in that it further includes an image processing circuit. The voltage application circuit also supplies two or more different sensitivity adjustment voltages to the pixel array. Since the configurations other than the image processing circuit and the voltage application circuit can be the same as those in the first embodiment, these circuits will be mainly described.

FIG. 17 schematically shows an example of the circuit configuration of the image pickup apparatus of this embodiment. The image pickup apparatus 104 shown in FIG. 17 further includes an image processing circuit 71 in addition to the configuration of the image pickup apparatus 101 of the first embodiment. The image pickup apparatus 104 of the present embodiment captures the same scene a plurality of times with different sensitivities, and synthesizes images having different sensitivities. By synthesizing a plurality of images acquired under different sensitivities, an image of a scene having a large contrast ratio without overexposure and underexposure is generated. Such a shooting method is called high dynamic range composition.

Here, the voltage application circuit 60 sequentially supplies two or more sensitivity adjustment voltages having a relationship of, for example, Vd1> Vd2 >> ...> Vdm (m is an integer of 2 or more) to each unit pixel cell 14.

The image pickup apparatus 104 takes an image in a state where the sensitivity adjustment voltages of Vd1, Vd2, ..., And Vdm are applied, respectively, and the image signal acquired by the image signal from the horizontal signal reading circuit 20 to the image processing circuit 71. Outputs G1, G2, ..., Gm. For example, in one frame, shooting is performed with V1 applied as the sensitivity adjustment voltage, and in the next frame, shooting is performed with one selected from Vd2 to Vdm applied as the sensitivity adjustment voltage.

For example, when the signal charge is a hole, the higher the sensitivity adjustment voltage, the higher the sensitivity of the image pickup device 104, and the lower the sensitivity adjustment voltage, the lower the sensitivity of the image pickup device 104. Therefore, at least, an image signal having a relatively low sensitivity and a small amount of overexposure and an image signal having a relatively high sensitivity and a small amount of blackout are output to the image processing circuit 71. The image processing circuit 71 generates, for example, a composite image obtained by synthesizing these two images and outputs the composite image. The method of synthesizing two or more images acquired with different sensitivities is not limited to a specific method, and various signal processing methods used for high dynamic range composition can be applied.

In the obtained composite image, the occurrence of overexposure or underexposure is suppressed even in the high-luminance portion and the low-luminance portion. As described above, according to the imaging device of the present embodiment, it is possible to expand the dynamic range of the photographing device.

(Modified example of the fourth embodiment)
FIG. 18 shows an example of arrangement of pixel electrodes and auxiliary electrodes in the image pickup apparatus according to the fourth embodiment. FIG. 18 extracts and exemplifies nine of a plurality of unit pixel cells in a pixel array. As described below, unit pixel cells having different functions may be mixed in the pixel array.

In the configuration illustrated in FIG. 18, the unit pixel cell 14C including the pixel electrode 50C and the unit pixel cell 14D including the pixel electrode 50D having an area smaller than the pixel electrode 50C are alternately arranged row by row. In FIG. 18, the unit pixel cell 14C is arranged in the odd-numbered rows of the pixel array, and the unit pixel cell 14D is arranged in the even-numbered rows of the pixel array. As shown in the figure, the row in which the unit pixel cell 14C is arranged (here, the odd row) and the row in which the unit pixel cell 14D is arranged (here, the even row) are formed so as to surround the pixel electrode 50C, respectively. An auxiliary electrode row 61 _{C and an auxiliary electrode row 61 D} formed so as to surround the pixel electrode 50 D are formed.

Between the pixel electrode 50C of the unit pixel cells 14C and the auxiliary electrode lines 61 _C, the gap is formed, its size (the distance between the pixel electrode 50C and the auxiliary electrode lines 61 _C) is a Lc be. Between the pixel electrode 50D of the unit pixel cells 14D and the auxiliary electrode lines 61 _D, a gap is formed, its size (the distance between the pixel electrode 50D and the auxiliary electrode lines 61 _D) is Ld
Is. As schematically shown in FIG. 18, here, the distance Ld is larger than the distance Lc. Therefore, for example, even _{when the same sensitivity adjustment voltage is applied to the auxiliary electrode row 61 C} and the auxiliary electrode row 61 _D , the region in which the signal charge is captured by the pixel electrode 50C formed in the unit pixel cell 14C. The size and the size of the region where the signal charge is captured by the pixel electrode 50D formed in the unit pixel cell 14D are different from each other. That is, in this example, even when a common sensitivity adjustment voltage is applied, the size of the region where the signal charge is captured by the pixel electrodes differs between the odd-numbered rows and the even-numbered rows. In other words, in the photosensitive region, the sensitivity when focusing on the unit pixel cell 14C and the sensitivity when focusing on the unit pixel cell 14D are different from each other.

In the image pickup apparatus having such an electrode structure, for example, the subject is photographed in a state where the same sensitivity adjustment voltage is applied to the _{auxiliary electrode row 61 C} and the auxiliary electrode row 61 _D. After shooting, for example, the image processing circuit 71 (see FIG. 17) constructs an image of the subject based on the output from each unit pixel cell.

At this time, the image processing circuit 71 uses the image signal output from the unit pixel cell 14C to form the first image, and uses the image signal output from the unit pixel cell 14D to form the second image. It is possible to do. In this example, even _{when the same sensitivity adjustment voltage is applied to the auxiliary electrode row 61 C} and the auxiliary electrode row 61 _D , a region formed in the unit pixel cell 14C where the signal charge is captured by the pixel electrode 50C. Since the size of the above and the size of the region where the signal charge is captured by the pixel electrode 50D formed in the unit pixel cell 14D are different from each other, the first image and the second image have different sensitivities. It can be said that the image was originally acquired. In other words, by mixing pixels with different gap sizes between the pixel electrode and the auxiliary electrode (here, the auxiliary electrode row) in the pixel array, images taken under different sensitivities can be displayed at once. Can be obtained.

As described above, according to the configuration illustrated in FIG. 18, images taken under different sensitivities can be acquired at one time. Therefore, for example, high dynamic range composition can be executed at higher speed.

The auxiliary electrode row 61 _C and the auxiliary electrode row 61 _D may be electrically separated from each other by being spatially separated as illustrated in FIG. 18, or may be electrically separated from each other by being formed as one. It may be connected to. By electrically isolating the auxiliary electrode lines 61 _C and the auxiliary electrode lines 61 _D each other, each independently different sensitivities adjusted voltage to the auxiliary electrode lines 61 _C and the auxiliary electrode lines 61 _D may be applied. When the auxiliary electrode row 61 _C and the auxiliary electrode row 61 _D are integrally formed, the number of wires between the voltage application circuit 60 and the pixel array can be reduced.

In the configuration illustrated in FIG. 18, the auxiliary electrodes are separated row by row. However, the configuration of the auxiliary electrode is not limited to this example, and for example, the auxiliary electrode may be separated for each unit pixel cell.

FIG. 19 shows another example of the arrangement of the pixel electrode and the auxiliary electrode in the image pickup apparatus according to the fourth embodiment. In the configuration illustrated in FIG. 19, each of the unit pixel cells 14E includes a pixel electrode 50 and an auxiliary electrode 61E. In the example shown in FIG. 19, the distance between the pixel electrode 50 and the auxiliary electrode 61E is the same among the nine unit pixel cells 14E shown in FIG.

As shown in the figure, in this example, the auxiliary electrode 61E is electrically separated from the other auxiliary electrodes 61E in the pixel array by providing a gap between the unit pixel cells 14E adjacent to each other. According to such a configuration, it is possible to independently apply different sensitivity adjustment voltages to each of the auxiliary electrodes 61E in the pixel array. By independently applying different sensitivity adjustment voltages to each of the auxiliary electrodes 61E in the pixel array, it is possible to adjust the sensitivity according to an arbitrary pattern in the pixel array.

FIG. 20 shows an example of an electrical connection between the unit pixel cell 14E including the pixel electrode 50 and the auxiliary electrode 61E and the voltage application circuit 60. The image pickup apparatus 104E shown in FIG. 20 has a sensitivity adjustment line 28 corresponding to each unit pixel cell 14E in each row of the pixel array. Specifically, the auxiliary electrode 61E of each unit pixel cell 14E and the voltage application circuit 60 are connected by sensitivity adjusting lines 28 different from each other. By connecting each auxiliary electrode 61E and the voltage application circuit 60 by different sensitivity adjustment lines 28, different sensitivity adjustment voltages can be independently applied to each auxiliary electrode 61E. If the values of the sensitivity adjustment voltages supplied to the unit pixel cells 14E belonging to the same row are common and different sensitivity adjustment voltages are applied between the odd-numbered rows and the even-numbered rows of the pixel array, refer to FIG. It is also possible to perform an operation similar to the operation described above.

FIG. 21 schematically shows an example of a cross section of the unit pixel cell 14E. FIG. 21 corresponds to the cross-sectional view taken along the line AA'shown in FIG. 19, and schematically shows three unit pixel cells arranged along the row direction.

In the configuration illustrated in FIG. 21, the unit pixel cell 14Eb shown in the center of the figure has a color filter 75b on the side opposite to the photoelectric conversion layer 51 with respect to the upper electrode 52. Here, the color filter 75b is a filter that transmits blue light. As shown in the figure, unit pixel cells 14Eg are arranged on the right side and the left side of the unit pixel cell 14Eb. Each of these two unit pixel cells 14Eg has a color filter 75g on the side opposite to the photoelectric conversion layer 51 with respect to the upper electrode 52. Here, the color filter 75g is a filter that transmits green light. As shown, the microlens 76 may be placed on the color filters (here, the color filters 75b and 75g).

Each of the unit pixel cell 14Eb and the unit pixel cell 14Eg shown in FIG. 21 has a pixel electrode 50 and an auxiliary electrode 61E. Therefore, the voltage application circuit 60 (see FIG. 20) can individually apply different sensitivity adjustment voltages to the auxiliary electrodes 61E of each unit pixel cell. Here, the voltage application circuit 60 supplies different sensitivity adjustment voltages to the auxiliary electrodes 61E of each unit pixel cell according to the color of the light transmitted through the color filter. For example, the voltage application circuit 60 applies the first voltage as the sensitivity adjustment voltage to the auxiliary electrode 61E of the B pixel having the color filter 75b, and applies the first voltage to the auxiliary electrode 61E of the G pixel having the color filter 75g as the sensitivity adjustment voltage. A second voltage different from the first voltage is applied. Further, the voltage application circuit 60 applies a third voltage different from the first and second voltages to the auxiliary electrode 61E of the R pixel (not shown in FIG. 21) having a color filter that transmits red light. ..

In this way, for example, by supplying different sensitivity adjustment voltages to the auxiliary electrodes 61E of each unit pixel cell according to the color of the light transmitted through the color filter, it is possible to individually set the sensitivity for each color. be. That is, the white balance of the acquired image can be adjusted by adjusting the sensitivity adjustment voltage.

What should be noted here is not to adjust the gain of each color in the image data obtained by shooting, but to change the sensitivity of each color at the time of shooting. In the conventional method of adjusting the gain of each color in the image data obtained by shooting, the noise level of each color is amplified at a different rate as the gain is changed. On the other hand, according to the present embodiment, since the sensitivity at the time of imaging can be arbitrarily changed for each color, the change in color in the entire image due to the noise level of each color being amplified at a different rate is suppressed. Can be done. Therefore, according to the present embodiment, it is possible to more easily realize the white balance according to the difference in the shooting environment (for example, in the morning or in the evening) or the difference in the light source.

(Fifth Embodiment)
The imaging apparatus according to this embodiment will be described with reference to FIG. 22.

The image pickup apparatus of the present embodiment is different from the image pickup apparatus of the first embodiment in that it further includes a memory. Since the configuration other than the memory can be the same as that of the first embodiment, the memory will be mainly described.

FIG. 22 schematically shows an example of the circuit configuration of the image pickup apparatus of this embodiment. The image pickup device 105 shown in FIG. 22 further includes a memory 78 in addition to the configuration of the image pickup device 101 of the first embodiment.

The memory 78 receives information on the sensitivity adjustment voltage (typically the value of the sensitivity adjustment voltage) applied to the auxiliary electrode 61 at the time of photographing from, for example, the voltage application circuit 60F, and temporarily holds the information. The information on the sensitivity adjustment voltage used at the time of shooting is associated with the acquired image signal and is read out together with the image signal or image data.

By holding the value of the sensitivity adjustment voltage used at the time of shooting in the memory 78, it is possible to provide information on the scene at the time of shooting after shooting. In other words, information about the sensitivity under which the shooting was performed can be used after shooting. For example, from the value of the sensitivity adjustment voltage associated with a certain image, whether the image was taken in a dark environment or not, the sensitivity was lowered by controlling the sensitivity adjustment voltage. It is possible to distinguish whether the image is obtained by the above.

The value of the sensitivity adjustment voltage can also be used in the above-mentioned high dynamic range synthesis. For example, the image processing circuit 71 (see FIG. 17) uses information on the sensitivity adjustment voltage associated with each of the plurality of images obtained by changing the sensitivity to increase the sensitivity at the time of capturing these images. The order of the images (which can be called the magnitude of the exposure) can be determined. The image processing circuit 71 can execute the composition of a plurality of images based on the order of high sensitivity at the time of shooting.

When a plurality of different sensitivity adjustment voltages are applied to the pixel array at the same time for shooting, the memory 78 holds information on which unit pixel cell and what magnitude of the sensitivity adjustment voltage is applied. You may. The memory 78 may be arranged inside the image pickup apparatus 105 or may be arranged outside the image pickup apparatus 105. Alternatively, the memory 78 may be configured to be removable from the main body of the image pickup apparatus 105. As the memory 78, a known storage device such as a RAM or a hard disk can be used.

(Sixth Embodiment)
The imaging apparatus according to the present embodiment will be described with reference to FIGS. 23, 24A, and 24B.

FIG. 23 shows an example of the arrangement of the pixel electrode and the auxiliary electrode in the image pickup apparatus according to the sixth embodiment. In the configuration illustrated in FIG. 23, each of the unit pixel cells 14G includes a pixel electrode 50 and an auxiliary electrode 61G arranged so as to surround the pixel electrode 50. As shown, the auxiliary electrodes 61G include sub-auxiliary electrodes 61a to 61d that are spatially separated from each other. Here, the sub-auxiliary electrodes 61a to 61d are arranged along each side of the rectangular pixel electrode.

Each of the sub-auxiliary electrodes 61a to 61d has an electrical connection with a voltage application circuit 60 (see, for example, FIG. 20), so that sensitivity adjustment voltages independent of each other can be applied. That is, in this example, the potentials of the sub-auxiliary electrodes 61a to 61d are independently controlled in each of the unit pixel cells 14G during the operation of the image pickup apparatus. As will be described in detail below, a plurality of sub-auxiliary electrodes are arranged in the unit pixel cell, and the voltage in each of the plurality of sub-auxiliary electrodes is controlled to impart a phase difference detection function to the unit pixel cell. It is possible.

FIG. 24A shows an example of the region 51A formed in the photoelectric conversion layer 51 of the unit pixel cell 14G. As described above, the region 51A is a region in which the signal charge is captured by the pixel electrode 50. FIG. 24A corresponds to the cross-sectional view taken along the line BB'shown in FIG. 23. For simplicity, FIG. 24A shows one schematic cross section in the center of the nine unit pixel cells shown in FIG. 23.

FIG. 24A schematically shows a region 51A in a state where a first sensitivity adjustment voltage (for example, -2V) is applied to the sub-auxiliary electrode 61a and a second sensitivity adjustment voltage (for example, 5V) is applied to the sub-auxiliary electrode 61d. It is shown in. Here, it is assumed that a common voltage is applied to the sub-auxiliary electrode 61b and the sub-auxiliary electrode 61c.

In the state shown in FIG. 24A, the potential of the sub-auxiliary electrode 61a is lower than the potential of the sub-auxiliary electrode 61d, and the sub-auxiliary electrode 61a has more signal charge (here, positive) as compared with the sub-auxiliary electrode 61d. Hole) is captured. That is, as schematically shown in FIG. 24A, the region 51Ba formed on the sub-auxiliary electrode 61a is the region 51 formed on the sub-auxiliary electrode 61d.
Larger than Bd. Therefore, the region 51A at this time has a shape biased to the right in the figure.

FIG. 24B schematically shows a region 51A in a state where the second sensitivity adjustment voltage is applied to the sub-auxiliary electrode 61a and the first sensitivity adjustment voltage is applied to the sub-auxiliary electrode 61d. In the state shown in FIG. 24B, the region 51Bd formed on the sub-auxiliary electrode 61d is larger than the region 51Ba formed on the sub-auxiliary electrode 61a. Therefore, the region 51A at this time has a shape biased to the left in the figure.

In this way, by independently controlling the potentials of the sub-auxiliary electrodes 61a and 61d, it is possible to extend the region 51A toward the sub-auxiliary electrodes 61a or 61d in the photoelectric conversion layer 51. Similarly, if the potentials of the sub-auxiliary electrodes 61b and 61c are adjusted in a state where the potentials of the sub-auxiliary electrodes 61a and 61d are shared, the region 51A can be extended upward or downward in FIG. 23. Further, for example, if the first sensitivity adjustment voltage is applied to the sub-auxiliary electrodes 61a and 61b and the second sensitivity adjustment voltage is applied to the sub-auxiliary electrodes 61c and 61d, the region 51A is directed toward the upper right in FIG. 23. Can be extended. In this way, by independently controlling the potentials of the sub-auxiliary electrodes 61a to 61d, it is possible to extend the region 51A in the photoelectric conversion layer 51 in an arbitrary direction.

For example, if the region 51A of a pixel in the pixel array is extended to the right as shown in FIG. 24A, and the region 51A of the pixel adjacent to the left side of the pixel is extended to the left as shown in FIG. 24B, a set of these pixels is formed. Can be used as a pixel for phase difference AF (Auto Focus). Needless to say, if a common sensitivity adjustment voltage is applied to the four sub-auxiliary electrodes 61a to 61d, the unit pixel cell 14G can function in the same manner as in the other embodiments described above.

As is clear from FIGS. 24A and 24B, in the present embodiment, the device structures of the unit pixel cell for imaging and the unit pixel cell for phase difference AF are common. Therefore, the phase difference AF can be realized without separately arranging the pixels for the phase difference AF in the pixel array or separately arranging the sensor for the phase difference AF in the image pickup apparatus. According to this embodiment, by controlling the sensitivity adjustment voltage applied to the sub-auxiliary electrode, any unit pixel cell in the pixel array can function as a pixel for phase difference AF, so that more flexible operation is possible. ..

The number, arrangement, and shape of the sub-auxiliary electrodes in the unit pixel cell are not limited to the example shown in FIG. 23, and can be arbitrarily set. In the present embodiment, it can be said that the "unit pixel cell" is the smallest unit constituting the repeating structure of the photosensitive region and includes at least one pixel electrode.

(7th Embodiment)
The image acquisition device according to the present embodiment will be described with reference to FIGS. 25A to 30.

In the image acquisition device according to the present embodiment, the subject is brought close to the photoelectric conversion unit of the imaging device, and the light transmitted through the subject is detected by the photoelectric conversion unit. By making the irradiation direction of the light transmitted through the subject different, the same pixel detects the light transmitted through different parts of the subject, and the obtained plurality of image signals are combined to obtain an image with high resolution.

FIG. 25A schematically shows the configuration of the image acquisition device according to the seventh embodiment of the present disclosure. The image acquisition device 106 shown in FIG. 25A includes a lighting system 81, an image pickup device 100, and an image processing unit 90.

As the image pickup apparatus 100, any of the image pickup apparatus of the first to sixth embodiments can be used. In this embodiment, for example, the image pickup apparatus 101 of the first embodiment is used. FIG. 25B schematically shows an example of the configuration of the lighting system 81. The lighting system 81 includes, for example, light sources 81a to 81i arranged in two dimensions.

FIG. 26A schematically shows the configuration of the lighting system 81 and the vicinity of the photoelectric conversion unit 10 of the image pickup apparatus 101. As shown in FIG. 26A, the subject 80 is arranged at a distance L2, for example, from the upper electrode 52 of the photoelectric conversion unit 10. The distance L2 is typically 1 mm or less, for example, about 0.1 μm or more and about 10 μm or less. The subject 80 is arranged parallel to the photoelectric conversion unit 10. Here, a condensing optical element such as a microlens is not arranged on the upper electrode 52 of the photoelectric conversion unit 10. The subject 80 is, for example, a light-transmitting sample (cells, stripped tissue, etc.) held on a slide.

The lighting system 81 is arranged at a position sufficiently distant from the photoelectric conversion unit 10. In FIG. 26A, three of the light sources 81a to 81i are shown. Of the light sources 81a, 81b, and 81c, the light source 81a is arranged near the center of a plurality of unit pixel cells 14 arranged two-dimensionally in the image pickup apparatus 101. On the other hand, the light sources 81b and 81c are located away from the vicinity of the center. The light sources 81a, 81b, and 81c are typically point light sources, but since they are sufficiently separated from the photoelectric conversion unit 10, the subject 80 is irradiated with illumination light that is parallel light. As shown in FIG. 26A, the light source 81a irradiates the subject 80 with illumination light from a direction perpendicular to the subject 80 on the photoelectric conversion unit 10. On the other hand, as shown in FIG. 26B, the light source 81b irradiates the subject 80 with illumination light from an oblique direction with respect to the normal direction of the subject 80. The same applies to the light source 81c. In this way, the illumination system 81 sequentially emits illumination light from a plurality of different irradiation directions with reference to the subject 80, and irradiates the subject 80 with the illumination light.

Next, a procedure for acquiring an image of the subject 80 by the image acquisition device 106 will be described.

First, a predetermined sensitivity adjustment voltage Vk is applied to the auxiliary electrode 61. As described in the first embodiment, by applying the sensitivity adjustment voltage to the auxiliary electrode 61, the signal charge generated in the region 51B including the portion of the photoelectric conversion layer 51 that overlaps with the auxiliary electrode 61 is generated. It moves to the auxiliary electrode 61. Further, the signal charge generated in the region 51A including the portion of the photoelectric conversion layer 51 that overlaps with the pixel electrode 50 is detected by the pixel electrode 50. That is, the size of the region 51A defines the pixel size.

Next, the light source 81a is turned on and the subject 80 is irradiated with the illumination light. The illumination light transmitted through the subject 80 is incident on the photoelectric conversion unit 10. As described above, among the light incident on the photoelectric conversion unit 10, the illumination light incident on the region 51A in which the signal charge is captured by the pixel electrode 50 is substantially detected. That is, of the subject 80, the region 80A located directly above the region 51A formed on the photoelectric conversion layer 51 is selectively photographed.

Next, as shown in FIG. 26B, the light source 81b is turned on and the subject 80 is irradiated with the illumination light. The illumination light from the light source 81b is obliquely incident on the normal line of the subject 80. Therefore, the light transmitted through the region 80B located diagonally above the region 51A of the photoelectric conversion layer 51, not the region 80A of the subject 80 located directly above the region 51A of the photoelectric conversion layer 51, is incident on the region 51A. .. As can be seen from FIG. 26B, the illumination light transmitted through the region 80A of the subject 80 is incident on the region 51B of the photoelectric conversion layer 51. Therefore, when the light source 81b is turned on, the area 80B of the subject is selectively photographed.

After that, the same shooting is performed using the light source 81g and the light source 81h of the lighting system 81 shown in FIG. 25B. FIG. 27 is a schematic plan view of the subject 80 and shows the regions 80A, 80B, 80G, and 80H photographed by the light sources 81a, 81b, 81g, and 81h. As shown in FIG. 26B, the region 51A of the photoelectric conversion layer 51 is located below the region 80A. By using the light sources 81b, 81g and 81h as schematically shown by arrows in FIG. 26B, the light transmitted through the regions 80B, 80G and 80H of the subject 80 can be detected in the region 51A of the photoelectric conversion layer 51. .. Therefore, the entire region of the subject 80 can be photographed by four times of photographing using the light sources 81a, 81b, 81g and 81h. That is, the regions 80A, 80B, 80G and 80H included in the region Px corresponding to one unit pixel cell 14 of the subject 80 and different from each other by four times of shooting while changing the illumination direction (see FIG. 27). ) Can be sequentially detected in the region 51A.

The image processing unit 90 includes, for example, one or more processors, and synthesizes image signals obtained by photographing with the light sources 81a, 81b, 81g and 81h, respectively. At this time, the image signals are rearranged so as to match the arrangement shown in FIG. 27. As a result, a high-resolution image of the subject having a higher resolution than the image of one shot using each of the light sources 81a, 81b, 81g and 81h is formed.

In the image acquisition device 106, the size of the region 51A of the photoelectric conversion layer 51 corresponding to the pixels determines the resolution of the subject to be photographed, and the resolution of the captured image can be improved by reducing the region 51A. Hereinafter, image acquisition of the subject 80 when the region 51A is reduced will be described with reference to FIGS. 28A to 28C and 29.

First, a predetermined sensitivity adjustment voltage Vh is applied to the auxiliary electrode 61. When the signal charge is a hole, the sensitivity adjustment voltage Vh is set lower than the above-mentioned Vk so that the region 51A of the photoelectric conversion layer 51 corresponding to the pixel becomes smaller. As a result, as shown in FIG. 28A, the region 51A of the photoelectric conversion layer 51 becomes smaller than the state shown in FIGS. 26A and 26B.

Next, the light source 81a is turned on and the subject 80 is irradiated with the illumination light. As a result, the area 80A of the subject 80 is photographed.

Next, as shown in FIG. 28B, the light source 81b is turned on and the subject 80 is irradiated with the illumination light. The illumination light from the light source 81b is obliquely incident on the normal line of the subject 80. When the light source 81b is turned on, the area 80B of the subject is photographed.

Next, as shown in FIG. 28C, the light source 81c is turned on and the subject 80 is irradiated with the illumination light. Similarly, the illumination light from the light source 81c is obliquely incident on the normal line of the subject 80. When the light source 81c is turned on, the area 80C of the subject is photographed.

After that, the light source 81d of the lighting system 81 shown in FIG. 25B is similarly photographed using the light source 81i. FIG. 29 is a schematic plan view of the subject 80, showing regions 80A to 80I photographed using the illumination light from the light sources 81a to 81i, respectively. By using the light sources 81b to 81i as schematically shown by arrows in FIGS. 28B and 28C, the light transmitted through the regions 80B to 80I of the subject 80 can be detected in the region 51A of the photoelectric conversion layer 51. Therefore, the entire region of the subject 80 can be photographed by nine times of photographing using the light sources 81a to 81i. That is, the light transmitted through different parts of the subject can be sequentially detected in the region 51A.

The image processing unit 90 rearranges and synthesizes the image signals obtained by photographing with the light sources 81a to 81i so as to match the arrangement shown in FIG. 29. As a result, a high-resolution image of the subject having a higher resolution than the image taken once each using the light sources 81a to 81i is formed.

Even if the sensitivity adjustment voltage is changed, the size of the unit pixel cell 14 does not change, and the pixel pitch does not change either. However, the size of the region 51A, which corresponds to the effective pixel size, can be changed. In the image acquisition device 106, since the size of the region 51A determines the resolution, it is possible to acquire a high-resolution image by determining and applying the value of the sensitivity adjustment voltage so that the size of the region 51A becomes small. can. For example, in the example shown in FIG. 27, by adjusting the area 51A to a size of 1/4 of the unit pixel cell 14, the size of the area 51A is four times as large as the size of the unit pixel cell 14. The image is acquired with resolution. In the example shown in FIG. 29, by adjusting the area 51A to 1/9 of the size of the unit pixel cell 14, the resolution of the area 51A is 9 times higher than that when the size of the area 51A is equal to the size of the unit pixel cell 14. I'm getting an image.

As described above, according to the image acquisition device of the present embodiment, the signal charge is captured by the pixel electrode 50 in the photoelectric conversion layer 51 by changing the sensitivity adjustment voltage applied to the auxiliary electrode 61. The size can be changed. Therefore, the resolution can be changed, and a higher resolution image can be acquired by reducing the size of the region 51A.

In the present embodiment, the illumination system 81 includes a plurality of light sources, and irradiates the subject with illumination light from a plurality of different irradiation directions depending on the position of the light sources. However, the lighting system may include one light source and orient the imaging device on which the subject is supported. For example, as shown in FIG. 30, the lighting system may be composed of a parallel light source 83 and a mechanism 82 that changes the posture of the subject. The mechanism 82 may be composed of, for example, a goniometer mechanism 82A and a rotation mechanism 82B. The goniometer mechanism 82A supports the image pickup apparatus 101 and the subject 80. According to this lighting system, the mechanism 82 can make the posture of the subject 80 different with respect to the parallel light light source 83. Therefore, the subject 80 can receive the illumination light of the parallel light light source 83 from a plurality of different directions with respect to the subject 80.

Further, it is useful for the image acquisition device to change the size of the region 51A in the photoelectric conversion layer 51 in which the signal charge is captured by the pixel electrode 50 by changing the sensitivity adjustment voltage applied to the auxiliary electrode 61. Not only that, it is also useful as an imaging device. That is, by reducing the size of the region 51A, the distance between the regions 51A of the pixels adjacent to each other becomes large, and it becomes possible to suppress the color mixing.

The image pickup device and the image acquisition device according to the present disclosure are useful for image pickup devices such as digital cameras and image sensors.

10 Photoelectric conversion unit 11 Amplification transistor 12 Reset transistor 13 Address transistor 14, 14B to 14E, 14Eg, 14Eb, 14G Unit pixel cell 15 Vertical scanning circuit 16 Photoelectric conversion unit control line 17 Vertical signal line 18 Load circuit 19 Column signal processing circuit 20 Horizontal signal readout circuit 21 Power supply wiring 22 Inversion amplifier 23 Feedback line 24 Charge storage node 26 Address signal line 27 Reset signal line 28 Sensitivity adjustment line 31 Semiconductor substrate 38A, 38B, 38C Gate insulation layer 39A, 39B, 39C Gate electrode 41A to 41E n-type impurity region 42 Element separation region 43A, 43B, 43C Interlayer insulation layer 45A, 45B Contact plug 46A, 46B, 46C Wiring 47A, 47B, 47C, 48 Plug 49 Wiring 50, 50B to 50D Pixel electrode 50a to 50i Sub-pixel electrode 51 Photoelectric conversion layer 51A, 51B, 51Ba, 51Bd, 51C, 51D region 52 Upper electrodes 60, 60A to 60D, 60F Voltage application circuits 61, 61B, 61E, 61G Auxiliary electrodes 61 _{1 to 61 n} , 61 _C , 61 _D Auxiliary Electrode line 61a to 61d Sub-auxiliary electrode 70 Light amount detection circuit 71 Image processing circuit 72 Flash 74 Input interface 75b, 75g Color filter 76 Microlens 78 Memory 80 Subject 81 Lighting system 83 Parallel light light source 81A to 81I region 81a to 81i Light source 82 Mechanism 82A Gonio mechanism 82B Rotation mechanism 90 Image processing unit 101, 103, 103A, 103B, 104, 104E, 105 Imaging device 100 Imaging device 106 Image acquisition device

Claims (17)

A photoelectric conversion layer that converts light into electric charges,
The first pixel including the first pixel electrode that collects the electric charge, and
A second pixel including the second pixel electrode that collects the electric charge, and
Auxiliary electrodes located between the first pixel and the second pixel,
With
The first pixel and the second pixel are adjacent to each other,
An imaging device in which the shortest distance between the first pixel electrode and the auxiliary electrode is different from the shortest distance between the second pixel electrode and the auxiliary electrode. A photoelectric conversion layer that converts light into electric charges,
The first pixel including the first pixel electrode that collects the electric charge, and
A second pixel including the second pixel electrode that collects the electric charge, and
Auxiliary electrodes located between the first pixel and the second pixel,
With
The first pixel and the second pixel are adjacent to each other,
An imaging device in which the sensitivity of the first pixel is different from the sensitivity of the second pixel. A photoelectric conversion layer that converts light into electric charges,
The first pixel including the first pixel electrode that collects the electric charge, and
A second pixel including the second pixel electrode that collects the electric charge, and
Auxiliary electrodes located between the first pixel and the second pixel,
With
The first pixel and the second pixel are adjacent to each other,
An imaging device in which the size of the region where the charge is captured by the first pixel electrode is different from the size of the region where the charge is captured by the second pixel electrode. The imaging device according to any one of claims 1 to 3, wherein the size of the first pixel electrode is larger than the size of the second pixel electrode. The imaging device according to claim 4, wherein the shortest distance between the first pixel electrode and the auxiliary electrode is smaller than the shortest distance between the second pixel electrode and the auxiliary electrode. The imaging device according to any one of claims 1 to 5, wherein the auxiliary electrode surrounds the first pixel electrode and the second pixel electrode. A plurality of the first pixel and the second pixel are provided.
The imaging apparatus according to any one of claims 1 to 6, wherein the plurality of first pixels are arranged one-dimensionally or two-dimensionally, and the plurality of second pixels are arranged one-dimensionally or two-dimensionally. .. The imaging device according to any one of claims 1 to 5, further comprising a first pixel electrode and an upper electrode facing the second pixel electrode. The imaging apparatus according to any one of claims 1 to 8, further comprising a first amplification transistor including a gate electrode electrically connected to the first pixel electrode. The imaging device according to any one of claims 1 to 9, wherein the auxiliary electrode is electrically separated from the first pixel electrode and the second pixel electrode.
A pixel including an upper electrode, an auxiliary electrode, and a pixel electrode that collects electric charges generated by photoelectric conversion.
A voltage application circuit capable of selectively applying a first voltage and a second voltage to the auxiliary electrode, and a voltage application circuit.
With
An imaging device in which the first voltage and the second voltage are applied in different frames. The imaging device according to claim 11, further comprising a plurality of the pixels, wherein the plurality of pixels are arranged one-dimensionally or two-dimensionally. The imaging device according to claim 11 or 12, wherein at least one of the first voltage and the second voltage is a negative voltage. A light amount detection circuit for detecting the amount of light per unit area incident on the photoelectric conversion layer is further provided.
The imaging device according to any one of claims 11 to 13, wherein the voltage application circuit applies a voltage based on the detection result of the light amount detection circuit. With more image processing circuits
The voltage application circuit applies different voltages in at least two frames and
The image pickup apparatus according to any one of claims 11 to 14, wherein the image processing circuit synthesizes image signals of at least two frames and outputs the combined image signals. The imaging device according to claim 3, wherein the auxiliary electrodes of the plurality of pixels are electrically connected to each other. The imaging device according to claim 16, wherein the voltage application circuit changes the voltage in units of two frames.

Images