Imaging element, imaging device, and apparatus

Abstract

To realize proper exposure in an image pickup device where one pattern is divided into plural blocks, a motion is detected for each block and an exposure time is controlled respectively.SOLUTION: Provided is an imaging element including a plurality of pixels that generate a pixel signal according to incident light, and a setting unit that sets an exposure condition for each of a plurality of blocks each including at least two of the pixels, in which the setting unit sets the exposure condition for each of the blocks such that a difference in the exposure condition between the blocks in each of the blocks is equal to or less than a threshold value.SELECTED DRAWING: Figure 5A

Description

[Technical Field]

[0001] The present invention relates to an imaging element, an imaging device, and an apparatus. [Background technology]

[0002] Patent Document 1 describes an imaging device that divides one screen into a plurality of blocks, detects motion for each block, and controls the exposure time for each block. [Prior art document] [Patent documents] [Patent Document 1] JP 2006-197192 A Summary of the Invention

[0003] A first aspect of the present invention provides an image sensor comprising: a plurality of pixels that generate pixel signals in response to incident light; and a setting unit that sets exposure conditions for a plurality of blocks, each block including at least two pixels, such that a difference in exposure conditions between the blocks is equal to or less than a threshold value.

[0004] A second aspect of the present invention provides an image sensor comprising a plurality of pixels that generate pixel signals in response to incident light, and a setting unit that sets exposure conditions for a plurality of blocks, each block including at least two pixels, the setting unit setting the exposure conditions for the blocks in response to at least two representative values ​​of luminance corresponding to the pixels in the block.

[0005] In a third aspect of the present invention, there is provided an imaging device including the imaging element of the first or second aspect.

[0006] A fourth aspect of the present invention provides an apparatus including an image sensor having a plurality of pixels that generate pixel signals in response to incident light, and a setting unit that sets exposure conditions for a plurality of blocks, each block including at least two pixels, where the setting unit sets exposure conditions for each block such that differences between the exposure conditions for each block are equal to or less than a threshold value.

[0007] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a cross-sectional view of the imaging element according to the present embodiment. [Figure 2] FIG. 2 is a diagram illustrating a pixel array and blocks of an imaging chip. [Figure 3] FIG. 2 is a circuit diagram corresponding to a block of the imaging chip. [Figure 4] FIG. 2 is a block diagram showing the functional configuration of an imaging element. [Figure 5A] FIG. 2 is a block diagram showing the functional configuration of the image sensor 100. [Figure 5B] FIG. 2 is a block diagram showing the functional configuration of the image sensor 100. [Figure 6] 1 is a block diagram showing a configuration of an imaging apparatus according to an embodiment of the present invention. [Figure 7] FIG. 10 is a flowchart showing an example of a process for setting exposure conditions. [Figure 8] FIG. 8 is a diagram comparing an image captured under exposure conditions set according to the flow of FIG. 7 with an image captured under exposure conditions set by another method. [Figure 9] FIG. 10 is a flowchart illustrating an example of a correction process for exposure conditions. [Figure 10] 10 is a diagram showing a specific example of setting the upper and lower limits of the exposure conditions shown in FIG. 9. FIG. [Figure 11]11 is a diagram comparing a captured image in which the range of exposure conditions is restricted according to the example of FIG. 10 with a captured image in which the range of exposure conditions is restricted by another method. [Figure 12] FIG. 12 is a diagram showing histograms of the exposure conditions used for the respective captured images shown in FIG. 11. [Figure 13] FIG. 10 is a flowchart showing another example of the exposure condition correction process. [Figure 14] 14A and 14B are diagrams illustrating a specific example of the exposure condition smoothing process shown in FIG. 13. [Figure 15] 15 is a diagram comparing exposure conditions before and after performing smoothing processing according to the example of FIG. 14. FIG. [Figure 16] FIG. 10 is a flowchart showing a modified example of the exposure condition setting process. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0010] 1 is a cross-sectional view of an image sensor 100 according to this embodiment. The image sensor 100 includes an image sensor chip 113 that outputs pixel signals corresponding to incident light, a signal processing chip 111 that processes the pixel signals, and a memory chip 112 that stores the pixel signals. The image sensor chip 113, signal processing chip 111, and memory chip 112 are stacked and electrically connected to one another by bumps 109, which are conductive connecting portions made of Cu or the like.

[0011] As shown in the figure, incident light is mainly incident in the positive direction of the Z axis, as indicated by the white arrow. In this embodiment, the surface of the imaging chip 113 on which the incident light is incident is referred to as the back surface. As shown by the coordinate axes, the left direction on the paper, perpendicular to the Z axis, is the positive X axis, and the front direction on the paper, perpendicular to the Z axis and the X axis, is the positive Y axis. In the following figures, the coordinate axes are displayed so that the orientation of each figure can be understood, based on the coordinate axes in Figure 1.

[0012] An example of the imaging chip 113 is a back-illuminated MOS image sensor. The PD layer 106 is arranged on the back side of the wiring layer 108. The PD layer 106 has a plurality of PDs (photodiodes) 104 arranged two-dimensionally and transistors 105 provided corresponding to the PDs 104.

[0013] A color filter 102 is provided on the incident light side of the PD layer 106 via a passivation film 103. There are multiple types of color filters 102 that transmit different wavelength ranges, and each has a specific arrangement corresponding to each PD 104. The arrangement of the color filters 102 will be described later. A set of a color filter 102, a PD 104, and a transistor 105 forms one pixel.

[0014] A microlens 101 is provided corresponding to each pixel on the incident light side of the color filter 102. The microlens 101 condenses the incident light toward the corresponding PD 104.

[0015] The wiring layer 108 has wiring 107 that transmits pixel signals from the PD layer 106 to the signal processing chip 111. The wiring 107 may be multi-layered, and may be provided with passive elements and active elements.

[0016] A plurality of bumps 109 serving as connection portions are arranged on the surface of the wiring layer 108. The plurality of bumps 109 are aligned with and joined to a plurality of bumps 109 provided on the opposing surface of the signal processing chip 111, thereby electrically connecting the imaging chip 113 and the signal processing chip 111.

[0017] Similarly, a plurality of bumps 109 serving as connecting portions are arranged on the opposing surfaces of the signal processing chip 111 and the memory chip 112. These bumps 109 are aligned and joined to each other, thereby electrically connecting the signal processing chip 111 and the memory chip 112.

[0018] The imaging element 100 is formed by bonding the imaging chip 113, the signal processing chip 111, and the memory chip 112 in a wafer state before they are separated into chips, and then dicing the bonded wafer.

[0019] When bonding wafers together, plasma is applied to the wafer surfaces using an activation device to activate the bonding surfaces of the wafers. The wafers with activated surfaces are bonded together by hydrogen bonds, van der Waals bonds, covalent bonds, and the like that are formed by contact, forming a laminated substrate. If the two wafers are hydrogen bonded by contact with each other, after forming the laminated substrate, the laminated substrate is placed in a heating device such as an annealing furnace and heated to form covalent bonds between the wafers.

[0020] The term "activation" includes treating the bonding surface of at least one of the substrates so that when the bonding surface of one wafer comes into contact with the bonding surface of another wafer, hydrogen bonds, van der Waals bonds, covalent bonds, etc. are generated, resulting in solid-state bonding without melting. In other words, activation includes generating dangling bonds (unbonded hands) on the wafer surface, thereby making it easier to form bonds.

[0021] More specifically, in an activation device, oxygen gas, which is a process gas, is excited to form plasma in a reduced-pressure atmosphere, and oxygen ions are irradiated onto the surfaces that will become the bonding surfaces of the two substrates. For example, if the wafer is a substrate with an SiO film formed on Si, the irradiation of this oxygen ion breaks the SiO bonds on the wafer surfaces that will become the bonding surfaces during lamination, forming dangling bonds of Si and O. The formation of such dangling bonds on the wafer surfaces is sometimes referred to as activation.

[0022] When a substrate with dangling bonds is exposed to the atmosphere, for example, moisture in the air binds to the dangling bonds, and the substrate surface becomes covered with hydroxyl groups (OH groups). The substrate surface becomes more likely to bond with water molecules, i.e., more likely to become hydrophilic. In other words, activation results in the substrate surface becoming more likely to become hydrophilic. Furthermore, in solid-state bonding, the presence of impurities such as oxides at the bonding interface, as well as defects at the bonding interface, affect the bonding strength. Therefore, cleaning the bonding surface can be considered part of the activation process.

[0023] Furthermore, the wafer may be activated by applying pure water or the like to the hydrophilized surface of the wafer that will become the bonding surface using an apparatus not shown, which causes OH groups to be attached to the wafer surface, i.e., the wafer surface is terminated with OH groups.

[0024] By heating the laminated substrate, the bumps 109 on each of the bonding surfaces of the two wafers are integrated with each other, forming an electrical connection between the wafers. By forming the bumps 109 from a material that melts at a low temperature, such as indium or a tin-silver alloy, the laminated substrate can be reflow-treated at a low temperature of 200°C or less. Alternatively, if the bumps 109 are made of a conductive metal such as copper, they expand during the heat treatment, causing the bumps 109 between the wafers to press together and bond by solid-state diffusion.

[0025] The bonding between the bumps 109 is not limited to Cu bump bonding by solid-phase diffusion, but may also employ micro-bump bonding by solder melting. For example, it is sufficient to provide one bump 109 for each pixel block described below. Therefore, the size of the bumps 109 may be larger than the pitch of the PDs 104. Furthermore, in a peripheral region other than the pixel region where the pixels are arranged, bumps larger than the bumps 109 corresponding to the pixel region may also be provided.

[0026] The signal processing chip 111 has TSVs (through silicon vias) 110 that connect circuits provided on the front and back surfaces of the chip to each other. The TSVs 110 are preferably provided in the peripheral region. The TSVs 110 may also be provided in the peripheral region of the imaging chip 113 and in the memory chip 112. The TSVs 110 may also be used to electrically connect circuits provided on the memory chip 112 and circuits provided on the imaging chip 113.

[0027] In this way, the imaging chip 113 and the signal processing chip 111 are bonded to each other by their opposing surfaces and the bumps 109. The signal processing chip 111 and the memory chip 112 are bonded to each other by their opposing surfaces and connected to each other by the bumps 109 and the TSVs 110 provided on the signal processing chip 111. Note that the signal processing chip 111 and the memory chip 112 may be bonded to each other by their opposing surfaces and connected to each other by at least one of the bumps 109 and the TSVs 110.

[0028] FIG. 2 is a diagram illustrating the pixel array and blocks 131 of the imaging chip 113. In particular, the imaging chip 113 is shown as viewed from the back side. More than 20 million pixels are arranged in a matrix in the pixel region. These pixels are divided into blocks, each containing at least two pixels. In this embodiment, one block consists of 16 pixels, or 4 pixels by 4 pixels. The grid lines in the diagram illustrate the concept of adjacent pixels collectively forming the block 131.

[0029] As shown in the partially enlarged view of the pixel region, block 131 contains four so-called Bayer arrays, arranged vertically and horizontally, each consisting of four pixels: green pixels Gb and Gr, blue pixels B, and red pixels R. The green pixels are pixels that have a green filter as the color filter 102 and receive light in the green wavelength band of incident light. Similarly, the blue pixels are pixels that have a blue filter as the color filter 102 and receive light in the blue wavelength band, and the red pixels are pixels that have a red filter as the color filter 102 and receive light in the red wavelength band.

[0030] 3 is a circuit diagram corresponding to block 131 of imaging chip 113. In the figure, a rectangle surrounded by a dotted line typically represents a circuit corresponding to one pixel. Note that at least some of the transistors described below correspond to transistor 105 in FIG. 1.

[0031] As described above, the block 131 is formed of 16 pixels. The 16 PDs 104 corresponding to the respective pixels are connected to transfer transistors 302, and each gate of each transfer transistor 302 is connected to a TX wiring 307 through which a transfer pulse is supplied. In this embodiment, the TX wiring 307 is commonly connected to the 16 transfer transistors 302.

[0032] The drain of each transfer transistor 302 is connected to the source of the corresponding reset transistor 303, and a so-called floating diffusion FD between the drain of the transfer transistor 302 and the source of the reset transistor 303 is connected to the gate of the amplification transistor 304. The drain of the reset transistor 303 is connected to a Vdd wiring 310 to which a power supply voltage is supplied, and the gate of the reset transistor 303 is connected to a reset wiring 306 to which a reset pulse is supplied. In this embodiment, the reset wiring 306 is commonly connected to the 16 reset transistors 303.

[0033] The drain of each amplification transistor 304 is connected to a Vdd wiring 310 to which a power supply voltage is supplied. The source of each amplification transistor 304 is connected to the drain of a corresponding selection transistor 305. The gate of each selection transistor is connected to a decoder wiring 308 to which a selection pulse is supplied. In this embodiment, the decoder wiring 308 is provided independently for each of the 16 selection transistors 305. The sources of each selection transistor 305 are connected to a common output wiring 309. A load current source 311 supplies a current to the output wiring 309. In other words, the output wiring 309 for the selection transistor 305 is formed by a source follower. The load current source 311 may be provided on the imaging chip 113 side or on the signal processing chip 111 side.

[0034] Here, we will explain the flow from the start of pixel exposure to the output of a pixel signal after exposure is completed. When a reset pulse is applied to the reset transistor 303 via the reset wiring 306 and at the same time a transfer pulse is applied to the transfer transistor 302 via the TX wiring 307, the potentials of the PD 104 and floating diffusion FD are reset and exposure begins.

[0035] When the transfer pulse application is stopped, the PD 104 converts the incident light it receives into electric charges and accumulates them. Then, when the transfer pulse is applied again without the reset pulse being applied, exposure ends. The electric charges accumulated up until the end of exposure are transferred to the floating diffusion FD, and the potential of the floating diffusion FD changes from the reset potential to the signal potential after exposure ends. When a selection pulse is applied to the selection transistor 305 via the decoder wiring 308, the fluctuation in the signal potential of the floating diffusion FD is transmitted to the output wiring 309 via the amplification transistor 304 and the selection transistor 305. As a result, a pixel signal corresponding to the reset potential and the signal potential is output from the unit pixel to the output wiring 309.

[0036] As shown in the figure, in this embodiment, the reset wiring 306 and TX wiring 307 are common to the 16 pixels that form the block 131. That is, the reset pulse and transfer pulse are each applied simultaneously to all 16 pixels. Therefore, all pixels that form the block 131 start and end exposure at the same timing. However, pixel signals corresponding to the accumulated charges are selectively output to the output wiring 309 by sequentially applying selection pulses to the respective selection transistors 305.

[0037] By configuring the circuit based on the block 131 in this way, the exposure time can be controlled for each block 131. Because the exposure time can be controlled for each block, adjacent blocks 131 can output pixel signals with different exposure times. Furthermore, a common exposure time can be set for all blocks 131, and a certain block 131 can be exposed once and output a pixel signal, while an adjacent block 131 can be repeatedly exposed twice and output a pixel signal. This latter type of repeated control of exposure and pixel signal output based on a common unit time is called unit time control. Note that when unit time control is performed, if the start and end points of exposure are synchronized across all blocks 131, the reset wiring 306 may be commonly connected to all reset transistors 303 on the imaging chip 113.

[0038] 4 is a block diagram showing the functional configuration of the image sensor 100. In particular, the flow of pixel signals will be explained here.

[0039] An analog multiplexer 411 sequentially selects the 16 PDs 104 that form the block 131 and outputs the respective pixel signals to the output wiring 309. The multiplexer 411 is formed in the imaging chip 113 together with the PDs 104.

[0040] The pixel signals output via the multiplexer 411 undergo correlated double sampling (CDS) and analog-to-digital (A / D) conversion by a signal processing circuit 412 formed in the signal processing chip 111, which performs CDS and A / D conversion. The A / D conversion converts the input analog pixel signals into 12-bit digital pixel signals. The A / D converted pixel signals are passed to an arithmetic circuit 415, also formed in the signal processing chip 111. The arithmetic circuit 415 performs arithmetic processing on the received pixel signals required for subsequent image processing, and passes the signals to the demultiplexer 413.

[0041] The demultiplexer 413 stores the received pixel signals in pixel memories 414 corresponding to the respective pixels. Each pixel memory 414 has a capacity capable of storing the pixel signals after arithmetic processing has been performed. The demultiplexer 413 and pixel memories 414 are formed on the memory chip 112.

[0042] The arithmetic circuit 415 reads pixel signals to be used for arithmetic processing from the pixel memory 414 via the demultiplexer 413. Alternatively, in accordance with an external transfer request, the arithmetic circuit 415 transfers the pixel signals read from the pixel memory 414 via the demultiplexer 413 to a downstream image processing unit. The arithmetic circuit 415 may be provided in the memory chip 112.

[0043] Also, while the figure shows the flow of pixel signals for one block, in reality these exist for each block and operate in parallel. However, a calculation circuit 415 does not have to exist for each block; for example, one calculation circuit 415 may process sequentially while referring to the values ​​of the pixel memories 414 corresponding to each block in order.

[0044] 5A is a block diagram showing the functional configuration of the image sensor 100. Here, the specific configuration of the signal processing chip 111 and the setting unit 460 provided in the memory chip 112 will be mainly described.

[0045] The signal processing chip 111 includes a sensor control unit 441, a synchronization control unit 443, and a signal control unit 444 as distributed control functions, and a drive control unit 420 that controls these control units. The drive control unit 420 converts instructions from a system control unit 501 that is responsible for integrated control of the entire imaging device into control signals that can be executed by each control unit, and passes them on to each unit.

[0046] The sensor control unit 441 is responsible for controlling the transmission of control pulses related to charge accumulation and charge readout of each pixel, which are sent to the imaging chip 113. Specifically, the sensor control unit 441 controls the start and end of exposure by sending reset pulses and transfer pulses to the target pixels, and outputs pixel signals to the output wiring 309 by sending selection pulses to the readout pixels.

[0047] The synchronization control unit 443 sends a synchronization signal to the imaging chip 113. Each pulse becomes active in the imaging chip 113 in synchronization with the synchronization signal. For example, by adjusting the synchronization signal, random control, thinning control, and the like can be realized, in which only specific pixels belonging to the same block 131 are the control targets.

[0048] The signal control unit 444 is mainly responsible for timing control of the A / D converter 412b. The pixel signals output via the output wiring 309 are input to the CDS circuit 412a and the A / D converter 412b via the multiplexer 411. The A / D converter 412b is controlled by the signal control unit 444 and converts the input pixel signals into digital signals. The converted digital pixel signals are passed to the arithmetic circuit 415, where they are subjected to arithmetic processing. The processed pixel signals are passed to the demultiplexer 413 of the memory chip 112 and stored as digital pixel values ​​in the pixel memories 414 corresponding to each pixel.

[0049] Furthermore, in response to a transfer request from the system control unit 501, the drive control unit 420 reads out the target pixel signal from the pixel memory 414 via the arithmetic circuit 415 and demultiplexer 413, and transfers the signal to the image processing unit 511 provided in the imaging device. The pixel memory 414 is provided with a data transfer interface that transmits the pixel signal in response to the transfer request. The data transfer interface is connected to a data transfer line that is connected to the image processing unit 511. The data transfer line is formed, for example, by a data bus among the bus lines. In this case, the transfer request from the system control unit 501 to the drive control unit 420 is executed by address specification using the address bus.

[0050] The transmission of pixel signals via the data transfer interface is not limited to the addressing method, and various other methods can be used. For example, a double data rate method can be used, which uses both the rising and falling edges of the clock signal used to synchronize each circuit when transferring data. A burst transfer method can also be used, which transfers data all at once by omitting some steps such as addressing, thereby increasing speed. It is also possible to use a combination of a bus method using lines connecting the control unit, memory unit, and input / output unit in parallel, and a serial method that transfers data one bit at a time in series.

[0051] With this configuration, the image processing unit 511 can receive only the necessary pixel signals, and therefore can complete image processing at high speed, especially when forming a low-resolution image.

[0052] The memory chip 112 further includes a setting unit 460 that sets exposure conditions for each block 131. The setting unit 460 acquires the luminance distribution of the scene from the system control unit 501, and sets exposure conditions for each block 131 according to the luminance distribution. The exposure conditions are conditions that change the brightness of the image to be acquired, such as exposure time, aperture value, and ISO sensitivity.

[0053] The setting unit 460 also corrects the exposure conditions in accordance with various requirements such as memory capacity, required dynamic range, etc. The setting and correction processing of the exposure conditions by the setting unit 460 will be described later. The setting unit 460 also determines the timing of opening and closing the shutter in accordance with the exposure time of each block 131.

[0054] The memory chip 112 further includes a mode switching unit 470 that switches the imaging mode depending on the exposure conditions. As an example, the mode switching unit 470 switches between a first mode in which the difference between the maximum exposure condition and the minimum exposure condition in the multiple blocks is a first value, and a second mode in which the difference is smaller than the first value.

[0055] Alternatively, the mode switching unit 470 may switch between a first mode in which the maximum absolute value of the difference between the exposure conditions of a first block among the multiple blocks and the exposure conditions of each of the multiple blocks adjacent to the first block is a first value, and a second mode in which the maximum value is smaller than the first value.

[0056] The setting and correction processing of exposure conditions by the setting unit 460 will be described later, but in the first mode, the exposure conditions are set so as to reduce the difference between adjacent blocks rather than the entire image, making it possible to capture images under equalized exposure conditions while suppressing the sacrifice of bright and dark areas. In the second mode, it is possible to capture images under even more equalized exposure conditions than in the first mode.

[0057] For example, the mode switching unit 470 receives an instruction from a user via the system control unit 501 and instructs the setting unit 460 to select either the first mode or the second mode. In the first mode, the setting unit 460 sets exposure conditions for each block 131 so that the maximum value of the difference between the exposure conditions is equal to or less than a first value, and passes the set exposure conditions to the drive control unit 420. On the other hand, in the second mode, the setting unit 460 sets exposure conditions for each block 131 so that the maximum value of the difference between the exposure conditions is smaller than the first value, and passes the set exposure conditions to the drive control unit 420. The drive control unit 420 controls the sensor control unit 441 to expose each pixel in accordance with the acquired exposure conditions.

[0058] Alternatively, the mode switching unit 470 may switch the imaging mode between a standard mode that uses a first exposure condition and a correction mode that uses a second exposure condition that is a correction of the first exposure condition. As an example, the first exposure condition is an exposure condition that is initially set by the setting unit 460 in accordance with the luminance distribution of the scene, and the second exposure condition is an exposure condition that is a correction of the first exposure condition.

[0059] As an example, the mode switching unit 470 receives an instruction from the user via the system control unit 501 and instructs the setting unit 460 to select either the standard mode or the correction mode. In the standard mode, the setting unit 460 sets the exposure conditions for each block 131, and then passes the set exposure conditions to the drive control unit 420 without correcting them. On the other hand, in the correction mode, the setting unit 460 sets the exposure conditions for each block 131, and then corrects the set exposure conditions and passes the corrected exposure conditions to the drive control unit 420. The drive control unit 420 controls the sensor control unit 441 to expose each pixel according to the acquired exposure conditions.

[0060] 5B is a block diagram showing the functional configuration of the image sensor 100. Here, a case where the setting unit 460 is provided in the signal processing chip 111 will be described.

[0061] 5A, the setting unit 460 acquires the luminance distribution of the scene from the system control unit 501 and sets the exposure conditions for each block 131 according to the luminance distribution. The setting unit 460 also corrects the exposure conditions according to various requirements such as memory capacity and required dynamic range. The setting unit 460 also determines the shutter opening and closing timing according to the exposure time of each block 131.

[0062] 5B, a mode switching unit 470 is also provided in the signal processing chip 111. As in the example shown in FIG. 5A, the mode switching unit 470 receives an instruction from a user via the system control unit 501 and instructs the setting unit 460 to select either the standard mode or the correction mode. In the standard mode, the setting unit 460 sets exposure conditions for each block 131 and then passes the set exposure conditions to the drive control unit 420 without correcting them. On the other hand, in the correction mode, the setting unit 460 sets exposure conditions for each block 131 and then corrects the set exposure conditions and passes the corrected exposure conditions to the drive control unit 420.

[0063] In this way, the setting unit 460 and the mode switching unit 470 may be provided in the memory chip 112 or in the signal processing chip 111. As shown in Fig. 5A, when the setting unit 460 and the mode switching unit 470 are provided in the memory chip 112, a larger space is secured in the signal processing chip 111 while increasing the transmission speed via the bumps 109 and the TSVs 110. As shown in Fig. 5B, when the setting unit 460 and the mode switching unit 470 are provided in the signal processing chip 111, they are on the same chip as the drive control unit 420 that performs overall control of each control unit, thereby realizing an increase in processing speed.

[0064] 6 is a block diagram showing the configuration of an imaging device according to this embodiment. The imaging device 500 includes a photographing lens 520 as an imaging optical system, which guides a subject light beam incident along an optical axis O to the image sensor 100. The photographing lens 520 may be an interchangeable lens that can be attached to and detached from the imaging device 500. The imaging device 500 mainly includes the image sensor 100, a system control unit 501, a photometry unit 503, a work memory 504, a recording unit 505, and a display unit 506. The system control unit 501 functions as an imaging instruction unit that receives instructions from a user and generates imaging instructions to be sent to the image sensor 100.

[0065] The photographing lens 520 is composed of a group of optical lenses, and focuses a subject light beam from a scene near its focal plane. Note that in FIG. 6, it is represented by a single virtual lens placed near the pupil. As described above, the drive control unit 420 of the image sensor 100 is a control circuit that controls the exposure of the image sensor 100 in accordance with instructions from the system control unit 501.

[0066] The image sensor 100 passes pixel signals to an image processing unit 511 in the system control unit 501. The image processing unit 511 performs various image processes using the work memory 504 as a workspace to generate image data. For example, when generating image data in JPEG file format, it performs white balance processing, gamma processing, etc., and then executes compression processing. The generated image data is recorded in a recording unit 505 and converted into a display signal, which is displayed on a display unit 506 for a predetermined time. The image processing unit 511 may be configured as an ASIC independent of the system control unit 501, or may be provided in the memory chip 112.

[0067] The photometry unit 503 detects the luminance distribution of a scene prior to a series of shooting sequences for generating image data. The photometry unit 503 includes, for example, an AE sensor with approximately one million pixels. The calculation unit 512 of the system control unit 501 receives the output of the photometry unit 503 and calculates the luminance of each region of the scene. The calculation unit 512 also performs various calculations for operating the imaging device 500. The calculation unit 512 may also perform the function of the setting unit 460 described above.

[0068] Next, the setting and correction of exposure conditions in the image sensor of this embodiment will be described with reference to the drawings.

[0069] Traditionally, cameras have a limited dynamic range that they can capture in one shot. For example, if you shoot with a short exposure time (sometimes called "short seconds") to match the bright areas of a scene, the dark areas of the image will be crushed. Conversely, if you shoot with a long exposure time (sometimes called "long seconds") to match the dark areas of a scene, the bright areas of the image will be blown out.

[0070] Therefore, in recent years, high dynamic range technology has been used to capture and combine multiple images to obtain images with a wide dynamic range. High dynamic range technology is a technique in which multiple images are captured under different exposure conditions, and only the necessary areas of each image are extracted and combined. This effectively expands the dynamic range.

[0071] However, if the gap between the bright and dark areas of a scene is large, the dynamic range becomes too wide, causing memory overflow. For example, if the dynamic range is the difference in EV value, ΔEV, the number of shots required for composition is 2. ΔEV It will be more than one piece.

[0072] [Exposure condition settings] 7 is a flow diagram showing an example of exposure condition setting processing. As described above, the setting unit 460 sets the exposure conditions for each block 131 according to the luminance distribution of the scene acquired from the system control unit 501. The luminance distribution of the scene may be calculated in response to a prior shooting instruction from the user. For example, when the system control unit 501 detects the pressing of the shutter switch, the photometry unit 503 executes photometry processing, and the calculation unit 512 calculates the luminance distribution of the scene based on the output from the photometry unit 503.

[0073] In process 710, the setting unit 460 calculates a representative value 1 from the luminance distribution. As an example, the representative value 1 is the average value (average luminance) of the luminance values ​​corresponding to the pixels in the target block 131.

[0074] In process 720, the setting unit 460 calculates a representative value 2 from the luminance distribution. As an example, the representative value 2 is the maximum value of the luminance corresponding to the pixels in the target block 131 (maximum luminance).

[0075] In process 730, the setting unit 460 sets the exposure conditions for the target block 131 according to the representative values ​​1 and 2. As an example, the setting unit 460 determines whether the average luminance and the maximum luminance are equal. If the setting unit 460 determines that the average luminance and the maximum luminance are equal, it sets the exposure time corresponding to the average luminance as the exposure condition for the target block 131. If the setting unit 460 determines that the maximum luminance is greater than the average luminance, it determines whether the pixels in the target block 131 will be saturated at the exposure time corresponding to the average luminance. If it determines that the pixels will not be saturated, it sets the exposure time corresponding to the average luminance as the exposure condition for the target block 131. Conversely, if it determines that the pixels will be saturated, it sets the exposure time corresponding to the maximum luminance as the exposure condition for the target block 131.

[0076] In process 740, the drive control unit 420 controls the sensor control unit 441 to expose each pixel under the exposure conditions set for each block 131, and the image processing unit 511 combines the generated images. Note that, as will be described later, the setting unit 460 may correct the set exposure conditions before process 740 and transfer the corrected exposure conditions to the drive control unit 420.

[0077] The maximum luminance may be calculated from a predetermined range of luminance from the top in a luminance histogram of the pre-captured image. The exposure times corresponding to the maximum luminance and average luminance are exposure times when the maximum and average luminance values ​​in the pre-captured image are converted to target maximum and average values, respectively, and may be calculated according to the following formulas.

number

number

[0078] where I 0,Max and I 0,Ave. are the maximum and average brightness values ​​in the pre-captured image, respectively, and t0 is the exposure time.Target,Max and I Target,Ave. are the target maximum and average values, respectively, and t Max and t Ave. are the exposure times corresponding to the target maximum and average values, respectively.

[0079] The setting section 460 may use the shorter of the exposure times corresponding to the two representative values, that is, the exposure time closer to the bright region, as shown in the following formula.

number

[0080] Here, t is the exposure time set as an exposure condition. Ave. If the pixels in the block 131 are saturated when the exposure time t Max may be adopted.

[0081] Figure 8 compares images captured under exposure conditions set according to the flow chart in Figure 7 with images captured under exposure conditions set using other methods. The top row (A) shows an image captured when the exposure time was set using only the average luminance value, along with the corresponding exposure time setting. The bottom row (B) shows an image captured when the exposure time was set using the average and maximum luminance values, along with the corresponding exposure time setting. Both images are of the same scene, that is, an outdoor view captured from indoors through a window. Note that the exposure time setting indicates that the brighter the color of the block (closer to white), the longer the exposure time (emphasis on dark areas), and the darker the color (closer to black), the shorter the exposure time (emphasis on bright areas).

[0082] In the captured image of (A), block boundaries are noticeable near the window frame and in the area where the lattice attached to the window intersects (particularly the area indicated by the white arrow). This is because when an area with a large difference in brightness, such as the window frame and lattice and the window glass, is included in one block 131, the pixels corresponding to the bright area become saturated when the exposure time is set using only the average brightness value, and sufficient information cannot be obtained. On the other hand, in (B), the average value is not used in such blocks, and the exposure time corresponding to the maximum value is set, so saturation does not occur and the adverse effects of (A) are not observed.

[0083] As described above, if the exposure conditions for block 131 are set according to the average brightness, there is a risk of saturation occurring in pixels corresponding to brightness values ​​greater than the average value. Therefore, if saturation does not occur under the exposure conditions corresponding to the average brightness, those exposure conditions are adopted, and if saturation does occur, exposure conditions corresponding to another representative value are adopted. This makes it possible to prevent saturation within block 131 while achieving appropriate exposure.

[0084] The exposure condition setting process described above is executed when setting the exposure conditions that will be the basis for the exposure condition correction process described next. Alternatively, the exposure condition setting process described above is executed to determine whether or not blown-out highlights or crushed shadows will occur under the exposure conditions set in the exposure condition correction process, and if it is determined that blown-out highlights or the like will occur, the correction process is repeatedly executed.

[0085] [Exposure condition correction] 9 is a flow chart showing an example of the exposure condition correction process. First, in process 910, the setting unit 460 sets the exposure condition for each block 131 as described above.

[0086] The setting unit 460 corrects the exposure conditions set for each block 131 so that the difference between the exposure conditions for each block 131 is equal to or less than a threshold. Specifically, in process 920, the setting unit 460 creates a histogram of the exposure conditions for each block 131. In process 930, the setting unit 460 sets upper and lower limits according to the histogram. That is, the setting unit 460 corrects the exposure conditions set for each block 131 so that the difference between the maximum and minimum values ​​in the histogram is equal to or less than a threshold.

[0087] Fig. 10 is a diagram showing a specific example of setting the upper and lower limits of the exposure conditions shown in Fig. 9. Here, the exposure condition is an exposure time TV, and the threshold TH (TV difference between the maximum TV and the minimum TV) is 5. Histogram H in (1) shows the histogram of the initial setting exposure conditions, where the maximum TV is 9 and the minimum TV is 2. Therefore, the TV difference is 7, which is larger than TH, so the exposure conditions need to be corrected.

[0088] The setting unit 460 compares the frequency of the maximum TV with the frequency of the minimum TV. Here, since the frequency of the maximum TV is smaller than the frequency of the minimum TV, the setting unit 460 corrects the maximum TV to the second largest TV. In other words, the frequency of TV9 is added to the second largest TV8. As a result of rounding the maximum TV, TV9, in this way, the histogram H of (2) is obtained.

[0089] In histogram H of (2), the maximum TV is 8 and the minimum TV is 2. Therefore, the TV difference is 6, which is greater than TH, so the exposure conditions need to be corrected. The setting unit 460 compares the frequency of the maximum TV with the frequency of the minimum TV. Here, since the frequency of the minimum TV is smaller than the frequency of the maximum TV, the setting unit 460 corrects the minimum TV to the second smallest TV. In other words, the frequency of TV2 is added to the second smallest TV3. As a result of rounding the minimum TV, TV2, in this way, histogram H of (3) is obtained.

[0090] In histogram H of (3), the maximum TV is 7 and the minimum TV is 3. Therefore, the TV difference is 5, which is equal to TH, so the processing ends without further correction of the exposure conditions. The setting unit 460 corrects the exposure conditions of the corresponding block 131 in accordance with histogram H of (3), and passes the corrected exposure conditions to the drive control unit 420. The subsequent processing is as described above, so a description thereof will be omitted.

[0091] Figure 11 compares images captured when the range of exposure conditions is limited according to the example of Figure 10 with images captured when the range of exposure conditions is limited by another method. (A) is an image captured when the range is limited while maintaining the maximum TV (emphasis on dark areas), (B) is an image captured when the range is limited while maintaining the minimum TV (emphasis on bright areas), and (C) is an image captured when the TV is limited according to the example of Figure 10. All images are of the same scene, i.e., an outdoor view captured from indoors through a window.

[0092] Figure 12 shows histograms of the exposure conditions used for each captured image shown in Figure 11. In (A), (B), and (C), the TV range of 3 to 17 in the original setting (O) is limited by a tolerance (threshold value TH) of 8 TV. The TV range of (A), which maintains the maximum TV, is 9 to 17 TV, with TVs below the lower limit of 9 TV being cut off. The TV range of (B), which maintains the minimum TV, is 3 to 11 TV, with TVs exceeding the upper limit of 11 TV being cut off. The TV range of (C), which is limited according to frequency, is 7 to 15, with TVs below the lower limit of 7 TV and TVs exceeding the upper limit of 15 TV being cut off.

[0093] Returning to Figure 11, we can see that (B), which emphasizes bright areas, is able to capture information about the scenery outside the window (buildings and trees), whereas (A), which emphasizes dark areas, is unable to capture the same information in the bright areas, resulting in overexposure. On the other hand, (C) is able to capture a certain amount of information in the same bright areas. Conversely, although not shown, (B), which emphasizes bright areas, has a worsening S / N ratio in dark areas, which could result in crushed shadows.

[0094] In this way, simply limiting the range of exposure conditions results in sacrificing either bright or dark regions, but by limiting the range according to the frequency of the exposure conditions, it is possible to minimize the sacrifice of bright and dark regions while preventing memory overflow.

[0095] Furthermore, the setting unit 460 limits the range of exposure conditions so that the amount of pixel signal data is equal to or less than the memory capacity as a result of cutting out the exposure conditions. The setting unit 460 may also preferentially cut out exposure conditions corresponding to dark regions. Since information about dark regions can be acquired even with short-second exposures, sufficient information can be acquired by adding together a large number of captured images. Furthermore, cutting out long-second exposure conditions can shorten the shooting time.

[0096] 13 is a flow diagram showing another example of the exposure condition correction process. The correction process of FIG. 13 may be executed subsequent to the correction process of FIG.

[0097] In process 1310, the setting unit 460 sets exposure conditions for each block 131. Process 1310 is similar to process 910 in Fig. 9, and therefore description thereof will be omitted. When the correction process in Fig. 13 is executed subsequent to the correction process in Fig. 9, process 1320, which will be described next, is executed after process 930 in Fig. 9 is executed.

[0098] In process 1320, the setting unit 460 performs a smoothing process of the exposure conditions for the target block 131. Here, the smoothing process refers to correcting the exposure conditions set for each block 131 so that the difference in exposure conditions between adjacent blocks 131 is equal to or less than the boundary threshold.

[0099] Fig. 14 is a diagram showing a specific example of the exposure condition smoothing process shown in Fig. 13. (1) shows the exposure conditions set in process 1310 for each of the blocks 131 arranged in a 3x4 matrix. Here, the exposure condition is the exposure time TV, and the threshold value (boundary threshold) for the TV difference between adjacent blocks is set to 3.

[0100] The setting unit 460 selects a target block to be subjected to the smoothing process from the arranged blocks 313, and of the nine blocks 131 adjacent to the target block on all four sides, the four L-shaped blocks 131 consisting of the three upper blocks 131 and one left block 131 are set as comparison blocks. Note that if the target block is located at the end of the arrangement, the number of comparison blocks may be less than four.

[0101] The setting unit 460 sequentially selects target blocks in the forward direction from the block array and performs the first smoothing process. Here, the forward direction starts from the upper left side of the block array. That is, the forward direction proceeds from the leftmost block 131 in the top row to the rightmost block 131, then from the leftmost block 131 in the second row from the top to the rightmost block 131, and finally from the leftmost block 131 in the bottom row to the rightmost block 131.

[0102] The specific steps of the smoothing process will be described. The setting unit 460 compares the TV of the target block with the minimum TV value of the comparison block. If the TV of the target block is greater than the minimum TV value of the comparison block and the difference is greater than a threshold, the setting unit 460 corrects the TV of the target block so that the difference is equal to or less than the threshold.

[0103] For example, when performing forward averaging on the block arrangement of (1), the upper left block 131 (TV10) is first selected as the target block. However, because this target block does not have a comparison block, the setting unit 460 does not perform averaging on the target block and moves on to the next target block. The next target block selected is the second block from the left in the top row, 131 (TV9). Because this target block has a comparison block (TV10) on its left, its TV becomes the minimum TV value of the comparison block. Because the TV of the target block (TV9) is less than the minimum TV value of the comparison block (TV10), the setting unit 460 does not perform averaging on the target block and moves on to the next target block. In this way, the setting unit 460 sequentially selects target blocks in the forward direction and performs averaging according to the TV difference.

[0104] As shown in (2), consider the case where the upper right block 131 (TV8) is selected as the target block. Since this target block has a comparison block (TV3) on its left, its TV becomes the minimum TV value of the comparison block. Since the TV of the target block (TV8) is greater than the minimum TV value of the comparison block (TV3), the setting unit 460 corrects the TV of the target block to 6 so that the difference from the minimum TV value of the comparison block (TV3) is equal to or less than the threshold value of 3.

[0105] (3) shows the block array resulting from the forward smoothing process, and the values ​​shown in white are the corrected TVs. However, there are still some TVs where the TV difference between adjacent blocks exceeds the threshold, such as the second block 131 (TV9) and the third block 131 (TV3) from the left in the top row.

[0106] After performing the smoothing process in the forward direction, the setting unit 460 resets the setting of the comparison blocks as shown in (4). Of the nine blocks 131 adjacent to the target block on all four sides, the setting unit 460 sets four L-shaped blocks 131 consisting of three blocks 131 on the bottom and one block 131 on the right side as comparison blocks. Note that if the target block is located at the end of the array, the number of comparison blocks may be less than four.

[0107] The setting unit 460 sequentially selects target blocks in the reverse direction from the block array and performs a second smoothing process. Here, the reverse direction starts from the lower right side of the block array. That is, the reverse direction proceeds from the rightmost block 131 in the bottom row to the leftmost block 131, then from the rightmost block 131 in the second row from the bottom to the leftmost block 131, and finally from the rightmost block 131 in the top row to the leftmost block 131. As shown in (5), the setting unit 460 corrects the TV of the target block according to the difference from the minimum TV value of the comparison block, as in the forward smoothing process.

[0108] (6) shows the block arrangement resulting from the reverse smoothing process, and the values ​​shown in white are the TVs corrected by the reverse smoothing process. As a result of performing the reverse smoothing process after the forward smoothing process, it can be seen that the TV differences between all adjacent blocks are below the threshold.

[0109] Since the S / N ratio is affected by the exposure time, if there is a large difference in the S / N ratio between adjacent blocks, the block boundaries will become noticeable. Therefore, by averaging the TV difference between adjacent blocks, it is possible to obtain a natural image with inconspicuous block boundaries, although the S / N ratio will deteriorate.

[0110] The threshold value may be uniquely determined depending on the characteristics of the image sensor, or an appropriate boundary threshold value may be determined based on the difference in S / N ratio obtained from a noise calculation formula by determining the relationship between the S / N ratio and the exposure time in advance.

[0111] 13 again, in process 1330, the drive control unit 420 controls the sensor control unit 441 to expose each pixel under the corrected exposure conditions, and the image processing unit 511 combines the generated images. Here, the image processing unit 511 may delete noise to compensate for differences in S / N ratio between blocks. Alternatively, the image processing unit 511 may add noise to the long-exposure block 131 or remove noise from the short-exposure block 131 to compensate for differences in S / N ratio between blocks.

[0112] Furthermore, the setting unit 460 may set the exposure conditions for each block 131 so that the proportion of pixels where whiteout or blackout occurs within the block 131 is a predetermined proportion. For example, the predetermined proportion is 10% or less for a 16×16 pixel block 131. By controlling specifically with numerical values ​​in this way, it is possible to reduce the probability that pixels where whiteout or blackout occurs exist at block boundaries, and obtain a natural image in which block boundaries are not noticeable.

[0113] FIG. 15 is a diagram comparing exposure conditions before and after performing the smoothing process according to the example of FIG. 14. (A) shows the exposure time setting before performing the smoothing process and the captured image. (B) shows the exposure time setting after performing the smoothing process. The subject is a skyscraper at night. The exposure time setting means that the brighter the color of the block (closer to white), the longer the exposure time (emphasis on dark areas), and the darker the color (closer to black), the shorter the exposure time (emphasis on bright areas).

[0114] As indicated by the arrow in image (A), the boundaries between adjacent blocks are conspicuous around the obstruction lights on the top floor of a high-rise building. This is due to the large difference in S / N ratio caused by the large contrast between the obstruction lights and the background night sky. Looking at the exposure time settings in (A), we can see that only the block corresponding to the obstruction light's position is exposed for a short time due to the influence of the light's brightness, and there is a large difference in exposure time between adjacent blocks. Therefore, by performing smoothing processing according to the example in Figure 14, the difference in exposure time between the block corresponding to the obstruction light's position and the surrounding blocks is smoothed, as shown in (B), resulting in a natural image with inconspicuous block boundaries.

[0115] 16 is a flow diagram showing a modified example of the exposure condition setting process. In process 1610, the setting unit 460 sets the exposure conditions according to the bright region. Specifically, the setting unit 460 acquires the exposure conditions corresponding to the bright region from the luminance distribution of the scene acquired from the system control unit 501, and sets the acquired exposure conditions to all blocks 131.

[0116] The exposure conditions corresponding to the bright region may be calculated according to the method of obtaining the maximum luminance from the luminance distribution, as described above. The calculation of the exposure conditions may take into account the maximum exposure time that takes into account camera shake suppression.

[0117] In process 1620, the setting unit 460 sets the number of images to be captured in accordance with the dynamic range to be acquired. The dynamic range to be acquired may be arbitrarily set by the user or designer, or may be automatically set by the system control unit 501 in accordance with the luminance distribution of the shooting scene. As described above, the required number of images to be captured is 2, where ΔEV is the dynamic range. ΔEV It will be more than one piece.

[0118] In process 1630, the setting unit 460 performs shooting in accordance with the set exposure conditions and number of shots, and in process 1640, the image processing unit 511 adds the shot images to synthesize an obtained image. Note that before process 1640, the image processing unit 511 may further perform detection and positioning of improper images due to camera shake or the like. If the required number of shots is insufficient after excluding improper images, the image processing unit 511 may send feedback to the drive control unit 420 to add more shots.

[0119] 1 to 15, in which different exposure conditions are set for each block 131, common exposure conditions are set for all blocks 131. Because exposure conditions are set to match the bright areas, there is no risk of overexposure, and information on dark areas can also be obtained by adding a large number of images. Furthermore, compared to when exposure conditions are changed block by block, the shooting and composition processes are simplified. Furthermore, because the same exposure conditions are set for all blocks 131, it is possible to suppress deterioration in image quality caused by misalignment of exposure conditions due to camera shake or other factors, which could lead to inappropriate acquisition of information.

[0120] In addition, because all acquired information is added, there is no waste and a good S / N ratio can be achieved.Furthermore, because it is shot with a short exposure, it is resistant to camera shake and the dynamic range can be expanded simply by increasing the number of shots.

[0121] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0122] In the above-described embodiment, an example has been shown in which the setting unit 460 and the mode switching unit 470 are provided in the memory chip 112 or the signal processing chip 111 of the image sensor 100, but the setting unit 460 and the mode switching unit 470 may be provided in an element, circuit, or board separate from the image sensor 100. In this case, for example, information on the luminance of pixels in each block 131 may be transmitted from the image sensor 100 to the setting unit 460 and the mode switching unit 470, respectively, and based on this, the setting unit 460 may set the exposure conditions or the mode switching unit 470 may switch the mode, and the results may be transmitted from the setting unit 460 and the mode switching unit 470 to the image sensor 100.

[0123] The setting unit 460 and the mode switching unit 470 may be provided in the same element, circuit, or substrate, or may be provided in different elements, circuits, or substrates. Furthermore, the element, circuit, or substrate on which the setting unit 460 and the mode switching unit 470 are provided may be provided in a device other than the imaging device 500.

[0124] It should be noted that the execution order of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order. (Item 1) a plurality of pixels that generate pixel signals in response to incident light; a setting unit that sets exposure conditions for each of a plurality of blocks, each of which includes at least two of the pixels; Equipped with The setting unit sets exposure conditions for each block so that a difference between the exposure conditions for each block is equal to or less than a threshold value. Image sensor. (Item 2) The setting unit sets the exposure conditions for each block so that the difference between the maximum exposure condition and the minimum exposure condition is equal to or less than the threshold value. Item 1. The imaging element according to item 1. (Item 3) The setting unit compares the frequency of occurrence of the maximum exposure condition and the frequency of occurrence of the minimum exposure condition, and if the frequency of occurrence of the maximum exposure condition is low, cuts out the maximum exposure condition, and if the frequency of occurrence of the minimum exposure condition is low, cuts out the minimum exposure condition. Item 2. The imaging element according to item 2. (Item 4) The setting unit preferentially cuts out exposure conditions corresponding to dark areas. Item 3. The imaging element according to item 3. (Item 5) further comprising a memory for storing the pixel signals; The setting unit sets exposure conditions for each block so that the amount of data of the pixel signals is equal to or less than the capacity of the memory. Item 2. The imaging device according to item 3. (Item 6) The setting unit sets exposure conditions for each block so that a difference between exposure conditions for adjacent blocks is equal to or less than the threshold value. 6. The imaging device according to any one of items 1 to 5. (Item 7) The setting unit sets exposure conditions for the block in accordance with at least two representative values ​​of luminance corresponding to pixels in the block. 7. The imaging device according to any one of items 1 to 6. (Item 8) the at least two representative values ​​include a maximum luminance and an average luminance corresponding to pixels in the block; The setting unit If the pixels in the block are saturated at the exposure time corresponding to the average luminance, the exposure time corresponding to the maximum luminance is set as an exposure condition for the block; If the pixels in the block are not saturated with the exposure time corresponding to the average luminance, the exposure time corresponding to the average luminance is set as an exposure condition for the block. Item 7. The imaging device according to item 7. (Item 9) a mode switching unit that switches between a first mode in which the difference between the maximum exposure condition and the minimum exposure condition in the plurality of blocks is a first value and a second mode in which the difference is smaller than the first value; 9. The imaging device according to any one of items 1 to 8. (Item 10) a mode switching unit that switches between a first mode in which the maximum absolute value of the difference between the exposure condition of a first block among the plurality of blocks and the exposure conditions of each of the plurality of blocks adjacent to the first block is a first value, and a second mode in which the maximum value is smaller than the first value; 9. The imaging device according to any one of items 1 to 8. (Item 11) The imaging device further includes a mode switching unit that switches the imaging mode between a standard mode using a first exposure condition and a correction mode using a second exposure condition obtained by correcting the first exposure condition. 9. The imaging device according to any one of items 1 to 8. (Item 12) an imaging chip on which the plurality of pixels are provided; and a chip stacked on the imaging chip on which the setting unit is provided. 12. The imaging device according to any one of items 1 to 11. (Item 13) The imaging chip; a signal processing chip that is stacked on the imaging chip and processes the pixel signals; a chip stacked on the signal processing chip and provided with the setting unit; Item 13. The imaging element according to item 12. (Item 14) the imaging chip and the signal processing chip are joined by their opposing surfaces and connection portions provided on the opposing surfaces, The signal processing chip and the chip on which the setting unit is provided are connected to each other by their opposing surfaces and at least one of the connection units provided on the opposing surfaces and the through electrodes provided on the signal processing chip. Item 14. The imaging device according to item 13. (Item 15) Furthermore, a memory chip having a memory for storing the pixel signals is stacked. Item 13. The imaging element according to item 12. (Item 16) a plurality of pixels that generate pixel signals in response to incident light; a setting unit that sets exposure conditions for each of a plurality of blocks, each of which includes at least two of the pixels; Equipped with The setting unit sets exposure conditions for the block based on at least two representative values ​​of luminance corresponding to pixels in the block. Image sensor. (Item 17) 17. An imaging device comprising the imaging element according to any one of items 1 to 16. (Item 18) an imaging element having a plurality of pixels that generate pixel signals in response to incident light; a setting unit that sets exposure conditions for each of a plurality of blocks, each of which includes at least two of the pixels; Equipped with The setting unit sets exposure conditions for each block so that a difference between the exposure conditions for each block is equal to or less than a threshold value. [Explanation of symbols]

[0125] 100 imaging element, 101 microlens, 102 color filter, 103 passivation film, 104 PD, 105 transistor, 106 PD layer, 107 wiring, 108 wiring layer, 109 bump, 110 TSV, 111 signal processing chip, 112 memory chip, 113 imaging chip, 131 block, 302 transfer transistor, 303 reset transistor, 304 amplification transistor, 305 selection transistor, 306 reset wiring, 307 TX wiring, 308 decoder wiring, 309 output wiring, 310 Vdd wiring, 311 load current source, 411 multiplexer, 412 signal processing circuit, 413 demultiplexer, 414 pixel memory, 415 arithmetic circuit, 420 drive control unit, 441 sensor control unit, 443 synchronization control unit, 444 Signal control unit, 460 setting unit, 470 mode switching unit, 500 imaging device, 501 system control unit, 503 photometry unit, 504 work memory, 505 recording unit, 506 display unit, 511 image processing unit, 512 calculation unit

Claims

[Claim 1] a first semiconductor substrate on which a plurality of pixel blocks, each including a photoelectric conversion unit that converts light into an electric charge, are arranged in a first direction and a second direction intersecting the first direction; a second semiconductor substrate that is stacked together with the first semiconductor substrate and has a setting unit that sets exposure conditions for a second pixel block that is disposed adjacent to the first pixel block among the plurality of pixel blocks, using a first signal based on charges converted by the photoelectric conversion unit included in a first pixel block among the plurality of pixel blocks; An imaging element comprising:

Images