Patent Publication Number: US-2021168318-A1

Title: Stacked light-receiving sensor and electronic device

Description:
FIELD 
     The present disclosure relates to a stacked light-receiving sensor and an in-vehicle imaging device. 
     BACKGROUND 
     Conventionally, flat-type image sensors in which chips such as a sensor chip, a memory chip, and a digital signal processor (DSP) chip are connected in parallel with a plurality of bumps exist as imaging devices that acquire still images and moving images. 
     In recent years, one-chip image sensors having a stack structure in which a plurality of dies are stacked have been developed for the purpose of miniaturization of imaging devices. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: WO2018/051809 
     SUMMARY 
     Technical Problem 
     In recent years, more advanced processing in image sensor chips is desired in terms of increasing the variety and the speed of image processing and protection of private information, for example. 
     The present disclosure develops a stacked light-receiving sensor and an in-vehicle imaging device capable of performing more advanced processing in a chip. 
     Solution to Problem 
     To solve the above-described problem, a stacked light-receiving sensor according to the present disclosure comprises: a first substrate; a second substrate bonded to the first substrate; and connection wiring attached to the second substrate, the first substrate including a pixel array in which a plurality of unit pixels are arranged in a two-dimensional matrix, the second substrate including a converter configured to convert an analog pixel signal output from the pixel array to digital image data and a processing unit configured to perform a process for data based on the image data, wherein at least a part of the converter is disposed on a first side in the second substrate, the processing unit is disposed on a second side opposite to the first side in the second substrate, and the connection wiring is attached to a side other than the second side in the second substrate. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating an overall configuration example of an imaging device as an electronic device according to a first embodiment. 
         FIG. 2  is a diagram illustrating a chip configuration example of an image sensor according to the first embodiment. 
         FIG. 3  is a diagram illustrating a layout example of a first substrate in a first layout example according to the first embodiment. 
         FIG. 4  is a diagram illustrating a layout example of a second substrate in the first layout example according to the first embodiment. 
         FIG. 5  is a diagram illustrating a layout example of the second substrate in a second layout example according to the first embodiment. 
         FIG. 6  is a diagram illustrating a layout example of the second substrate in a third layout example according to the first embodiment. 
         FIG. 7  is a diagram illustrating a layout example of the second substrate in a fourth layout example according to the first embodiment. 
         FIG. 8  is a diagram illustrating a layout example of the second substrate in a fifth layout example according to the first embodiment. 
         FIG. 9  is a diagram illustrating a layout example of the second substrate in a sixth layout example according to the first embodiment. 
         FIG. 10  is a diagram illustrating a layout example of the second substrate in a seventh layout example according to the first embodiment. 
         FIG. 11  is a diagram illustrating a layout example of the second substrate in an eighth layout example according to the first embodiment. 
         FIG. 12  is a diagram illustrating a layout example of the second substrate in a ninth layout example according to the first embodiment. 
         FIG. 13  is a layout diagram illustrating an overall configuration example of the first substrate in an image sensor according to a second embodiment. 
         FIG. 14  is a diagram illustrating a chip configuration example of the image sensor according to the second embodiment. 
         FIG. 15  is a layout diagram illustrating an overall configuration example of the first substrate in an image sensor according to a third embodiment. 
         FIG. 16  is a layout diagram illustrating an overall configuration example of the second substrate in the image sensor according to the third embodiment. 
         FIG. 17  is a diagram illustrating a chip configuration example of the image sensor according to the third embodiment. 
         FIG. 18  is a diagram illustrating an overall configuration example of an imaging device according to a fourth embodiment. 
         FIG. 19  is a diagram illustrating an attachment example of the imaging device according to a first example of the fourth embodiment. 
         FIG. 20  is a diagram illustrating an attachment example of the imaging device according to a second example of the fourth embodiment. 
         FIG. 21  is a block diagram illustrating an example of the overall configuration of a vehicle control system. 
         FIG. 22  is a diagram illustrating an example of the installation position of a vehicle exterior information detector and an imager. 
         FIG. 23  is a diagram illustrating an example of the overall configuration of an endoscopic surgery system. 
         FIG. 24  is a block diagram illustrating an example of the functional configuration of a camera head and a CCU. 
         FIG. 25  is a block diagram illustrating an example of the overall configuration of a diagnostic assistance system. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present disclosure will be described in detail below with reference to the drawings. In the following embodiments, the same parts are denoted by the same reference signs and an overlapping description will be omitted. 
     The present disclosure will be described in the order of items below. 
     1. First Embodiment 
     1.1 Overall Configuration Example of Imaging Device 
     1.2 Chip Configuration Example of Image Sensor Chip 
     1.3 Technical Problem of Image Sensor Chip Equipped with Processing Unit Performing Computation Based on Pre-Trained Model 
     1.4 Noise Reduction Method 
     1.4.1 First Layout Example 
     1.4.1.1 Layout Example of First Substrate 
     1.4.1.2 Layout Example of Second Substrate 
     1.4.2 Second Layout Example 
     1.4.3 Third Layout Example 
     1.4.4 Fourth Layout Example 
     1.4.5 Fifth Layout Example 
     1.4.6 Sixth Layout Example 
     1.4.7 Seventh Layout Example 
     1.4.8 Eighth Layout Example 
     1.4.9 Ninth Layout Example 
     1.5 Operation Effects 
     2. Second Embodiment 
     2.1 Chip Configuration Example of Image Sensor Chip 
     2.2 Operation Effects 
     3. Third Embodiment 
     3.1 Chip Configuration Example of Image Sensor Chip 
     3.2 Operation Effects 
     4. Fourth Embodiment 
     4.1 Configuration Example 
     4.2 Attachment Example 
     4.2.1 First Example 
     4.2.2 Second Example 
     4.3 Operation Effects 
     5. Application to Other Sensors 
     6. Application to Movable Body 
     7. Application to Endoscopic Surgery System 
     8. Application to Whole Slide Imaging (WSI) System 
     1. First Embodiment 
     First of all, a first embodiment will be described in detail with reference to the drawings. 
     1.1 Overall Configuration Example of Imaging Device 
       FIG. 1  is a block diagram illustrating an overall configuration example of an imaging device as an electronic device according to the first embodiment. As illustrated in  FIG. 1 , an imaging device  1  includes an image sensor  10  that is a solid-state imaging device and an application processor  20 . The image sensor  10  includes an imager  11 , a controller  12 , a converter (analog-to-digital converter, hereinafter referred to as ADC)  17 , a signal processor  13 , a digital signal processor (DSP)  14 , a memory  15 , and a selector (also referred to as output module)  16 . 
     The controller  12  controls each part in the image sensor  10  in accordance with user&#39;s operation or a set operation mode, for example. 
     The imager  11  includes, for example, an optical system  104  including a zoom lens, a focus lens, and an aperture, and a pixel array  101  having a configuration in which unit pixels (unit pixels  101   a  in  FIG. 2 ) including light-receiving elements such as photodiodes are arranged in a two-dimensional matrix. External incident light passes through the optical system  104  to form an image on a light-receiving surface that is an array of light-receiving elements in the pixel array  101 . Each unit pixel  101   a  in the pixel array  101  converts light incident on its light-receiving element into electricity to accumulate charge in accordance with the quantity of incident light so that the charge can be read out. 
     The ADC  17  converts an analog pixel signal for each unit pixel  101   a  read from the imager  11  to a digital value to generate digital image data and outputs the generated image data to the signal processor  13  and/or the memory  15 . The ADC  17  may include a voltage generating circuit that generates a drive voltage for driving the imager  11  from power supply voltage and the like. 
     The signal processor  13  performs a variety of signal processing for digital image data input from the ADC  17  or digital image data read from the memory  15  (hereinafter referred to as process target image data). For example, when the process target image data is a color image, the signal processor  13  converts the format of this image data to YUV image data, RGB image data, or the like. The signal processor  13  performs, for example, processing such as noise removal and white balance adjustment for the process target image data, if necessary. In addition, the signal processor  13  performs a variety of signal processing (also referred to as pre-processing) for the process target image data in order for the DSP  14  to process the image data. 
     The DSP  14  executes, for example, a computer program stored in the memory  15  to function as a processing unit that performs a variety of processing using a pre-trained model (also referred to as neural network calculation model) created by machine learning using a deep neural network (DNN). This pre-trained model (neural network calculation model) may be designed based on parameters generated by inputting, to a predetermined machine learning model, training data in which an input signal corresponding to output of the pixel array  101  is associated with a label for the input signal. The predetermined machine learning model may be a learning model using a multi-layer neural network (also referred to as multi-layer neural network model). 
     For example, the DSP  14  performs a computation process based on the pre-trained model stored in the memory  15  to perform a process of combining image data with a dictionary coefficient stored in the memory  15 . The result obtained through such a computation process (computation result) is output to the memory  15  and/or the selector  16 . The computation result may include image data obtained by performing a computation process using the pre-trained model and a variety of information (metadata) obtained from the image data. A memory controller for controlling access to the memory  15  may be embedded in the DSP  14 . 
     The image data to be processed by the DSP  14  may be image data normally read out from the pixel array  101  or may be image data having a data size reduced by decimating pixels of the image data normally read out. Alternatively, the image data to be processed may be image data read out in a data size smaller than normal obtained by performing readout from the pixel array  101  with pixels decimated. As used herein “normal readout” may be readout without decimating pixels. 
     The memory  15  stores image data output from the ADC  17 , image data subjected to signal processing by the signal processor  13 , the computation result obtained from the DSP  14 , and the like, if necessary. The memory  15  stores an algorithm of the pre-trained model to be executed by the DSP  14 , in the form of a computer program and a dictionary coefficient. 
     The DSP  14  can perform the computation process described above by training a learning model by changing the weights of a variety of parameters in the learning model using training data, by preparing a plurality of learning models and changing a learning model to be used in accordance with a computation process, or by acquiring a pre-trained learning model from an external device. 
     The selector  16 , for example, selectively outputs image data output from the DSP  14 , or image data or a computation result stored in the memory  15 , in accordance with a select control signal from the controller  12 . When the DSP  14  does not process image data output from the signal processor  13  and the selector  16  outputs the image data output from the DSP  14 , the selector  16  outputs the image data output from the signal processor  13  as it is. 
     As described above, the image data or the computation result output from the selector  16  is input to the application processor  20  that processes display and user interface. The application processor  20  is configured, for example, with a central processing unit (CPU) and executes an operating system and a variety of application software. This application processor  20  may be equipped with functions such as a graphics processing unit (GPU) and a baseband processor. The application processor  20  performs a variety of processes for the input image data or the computation result as necessary, or performs display to users, or transmits the input image data or the computation result to an external cloud server  30  through a predetermined network  40 . 
     For example, a variety of networks such as the Internet, a wired local area network (LAN) or a wireless LAN, a mobile communication network, or Bluetooth (registered trademark) can be applied to the predetermined network  40 . The image data or the computation result may be transmitted not only to the cloud server  30  but also to a variety of information processing devices (systems) having a communication function, such as a server operating on its own, a file server storing a variety of data, and a communication terminal such as a mobile phone. 
     1.2 Chip Configuration Example of Image Sensor Chip 
     An example of the chip configuration of the image sensor  10  illustrated in  FIG. 1  will now be described in detail below with reference to the drawings. 
       FIG. 2  is a diagram illustrating a chip configuration of the image sensor according to the present embodiment. As illustrated in  FIG. 2 , the image sensor  10  has a stack structure in which a first substrate (die)  100  shaped like a quadrangular flat plate and a second substrate (die)  120  similarly shaped like a quadrangular flat plate are bonded together. 
     The first substrate  100  and the second substrate may have the same size, for example. The first substrate  100  and the second substrate  120  each may be a semiconductor substrate such as a silicon substrate. 
     In the first substrate  100 , in the configuration of the image sensor  10  illustrated in  FIG. 1 , the pixel array  101  of the imager  11  is provided. A part or the whole of the optical system  104  may be provided on a chip in the first substrate  100 . 
     In the second substrate  120 , in the configuration of the image sensor  10  illustrated in  FIG. 1 , the ADC  17 , the controller  12 , the signal processor  13 , the DSP  14 , the memory  15 , and the selector  16  are arranged. A not-illustrated interface circuit, driver circuit, and the like may be arranged in the second substrate  120 . 
     The first substrate  100  and the second substrate  120  may be bonded together by chip-on-chip (CoC) technology in which the first substrate  100  and the second substrate  120  are individually diced into chips, and these diced first substrate  100  and second substrate  120  are bonded together, or by chip-on-wafer (CoW) technology in which one of the first substrate  100  and the second substrate  120  (for example, the first substrate  100 ) is diced into a chip, and the diced first substrate  100  is bonded to the second substrate  120  before dicing (that is, in a wafer state), or by wafer-on-wafer (WoW) technology in which the first substrate  100  and the second substrate  120  both in a wafer state are bonded together. 
     For example, plasma joining can be used as a joining process between the first substrate  100  and the second substrate  120 . However, the present invention is not limited thereto and a variety of joining processes may be used. 
     1.3 Technical Problem of Image Sensor Chip Equipped with Processing Unit Performing Computation Based on Pre-Trained Model 
     When the DSP  14  operates as a processing unit that performs a computation process based on a pre-trained model as described above, implementation of its operation algorithm is software implementation by running computer programs. Operation algorithms for pre-trained models are updated day by day. It is therefore difficult to grasp in advance, for example, at which timing the DSP  14  performing a computation process based on a pre-trained model performs a process or at which timing a process of the DSP  14  peaks. 
     As illustrated in  FIG. 2 , in the case where the DSP  14  operates as a processing unit that performs computation based on a pre-trained model in a chip configuration in which the pixel array  101  is mounted on the first substrate  100  and the DSP  14  is mounted on the second substrate  120 , if the DSP  14  starts a computation process or a process in the DSP  14  reaches a peak during resetting of the pixel array  101 , during exposure of the pixel array  101 , or during readout of a pixel signal from each unit pixel  101   a  of the pixel array  101 , noise is superimposed on a pixel signal read out from the pixel array  101 , and consequently, the quality of the image acquired by the image sensor  10  is deteriorated. 
     The present embodiment then reduces intrusion of noise resulting from the signal processing by the DSP  14  into the pixel array  101 , by adjusting the positional relation between the pixel array  101  and the DSP  14 . Accordingly, an image with less deterioration in quality can be acquired even when the DSP  14  operates as a processing unit that performs computation based on a pre-trained model. 
     1.4 Noise Reduction Method 
     The positional relation between the pixel array  101  and the DSP  14  according to the present embodiment will now be described in detail below with reference to the drawings. In the following, the positional relation between the pixel array  101  and the DSP  14  will be described by taking several examples of the layout (also referred to as floor map) of layers (the first substrate  100  and the second substrate  120 ). 
     1.4.1 First Layout Example 
       FIG. 3  and  FIG. 4  are diagrams for explaining a first layout example according to the present embodiment.  FIG. 3  illustrates a layout example of the first substrate  100 , and  FIG. 4  illustrates a layout example of the second substrate  120 . 
     1.4.1.1 Layout Example of First Substrate 
     As illustrated in  FIG. 3 , in the first substrate  100 , in the configuration of the image sensor  10  illustrated in  FIG. 1 , the pixel array  101  of the imager  11  is provided. When a part or the whole of the optical system  104  is mounted on the first substrate  100 , it is provided at a position corresponding to the pixel array  101 . 
     The pixel array  101  is provided off-center to one side L 101  among four sides L 101  to L 104  of the first substrate  100 . In other words, the pixel array  101  is provided such that its center O 101  is more proximate to the side L 101  than the center O 100  of the first substrate  100 . When the surface having the pixel array  101  in the first substrate  100  is rectangular, the side L 101  may be, for example, a shorter side. However, the present invention is not limited thereto, and the pixel array  101  may be provided off-center to a longer side. 
     In a region proximate to the side L 101  among four sides of the pixel array  101 , in other words, a region between the side L 101  and the pixel array  101 , a TSV array  102  is provided, in which a plurality of through silicon vias (hereinafter referred to as TSVs) passing through the first substrate  100  are arranged as wiring for electrically connecting each unit pixel  101   a  in the pixel array  101  to the ADC  17  provided in the second substrate  120 . In this way, the TSV array  102  is provided in proximity to the side L 101  proximate to the pixel array  101  to ensure a space for each part such as the ADC  17  in the second substrate  120 . 
     The TSV array  102  may also be provided in a region proximate to one side L 104  (or may be the side L 103 ) of two sides L 103  and L 104  intersecting the side L 101 , in other words, in a region between the side L 104  (or the side L 103 ) and the pixel array  101 . 
     A pad array  103  having a plurality of pads arranged linearly is provided on each of the sides L 102  and L 103 , on which the pixel array  101  is not provided off-center, among four sides L 101  to L 104  of the first substrate  100 . The pads included in the pad array  103  include, for example, a pad (also referred to as power supply pin) receiving power supply voltage for analog circuits such as the pixel array  101  and the ADC  17 , a pad (also referred to as power supply pin) receiving power supply voltage for digital circuits such as the signal processor  13 , the DSP  14 , the memory  15 , the selector  16 , and the controller  12 , a pad (also referred to as signal pin) for interfaces such as a mobile industry processor interface (MIPI) and a serial peripheral interface (SPI), and a pad (also referred to as signal pin) for input/output of clock and data. Each pad is electrically connected to, for example, an external power supply circuit or an interface circuit through a wire. It is preferable that each pad array  103  and the TSV array  102  are sufficiently spaced apart to such a degree that influences of reflection of signals from the wire connected to each pad in the pad array  103  can be ignored. 
     1.4.1.2 Layout Example of Second Substrate 
     On the other hand, as illustrated in  FIG. 4 , in the second substrate  120 , in the configuration of the image sensor  10  illustrated in  FIG. 1 , the ADC  17 , the controller  12 , the signal processor  13 , the DSP  14 , and the memory  15  are arranged. In the first layout example, the memory  15  is divided into two regions: a memory  15 A and a memory  15 B. Similarly, the ADC  17  is divided into two regions: an ADC  17 A and a digital-to-analog converter (DAC)  17 B. The DAC  17 B supplies a reference voltage for AD conversion to the ADC  17 A and, broadly speaking, is included in a part of the ADC  17 . Although not illustrated in  FIG. 4 , the selector  16  is also provided on the second substrate  120 . 
     The second substrate  120  also has wiring  122  in contact with and electrically connected to the TSVs in the TSV array  102  passing through the first substrate  100  (hereinafter simply referred to as TSV array  102 ), and a pad array  123 , in which a plurality of pads electrically connected to the pads in the pad array  103  of the first substrate  100  are arranged linearly. 
     For the connection between the TSV array  102  and the wiring  122 , for example, the following technology can be employed: twin TSV technology in which two TSVs, namely, a TSV provided in the first substrate  100  and a TSV provided from the first substrate  100  to the second substrate  120  are connected with the chip facing out, or shared TSV technology in which a shared TSV provided from the first substrate  100  to the second substrate  120  provides connection. However, the present invention is not limited thereto, and a variety of connection modes can be employed. Examples include Cu—Cu bonding in which copper (Cu) exposed on the joint surface of the first substrate  100  and Cu exposed on the joint surface of the second substrate  120  are joined. 
     The connection mode between the pads in the pad array  103  on the first substrate  100  and the pads in the pad array  123  of the second substrate  120  is, for example, wire bonding. However, the present invention is not limited thereto, and connection modes such as through holes and castellation may be employed. 
     In a layout example of the second substrate  120 , for example, the ADC  17 A, the signal processor  13 , and the DSP  14  are arranged in order from the upstream side along the flow of a signal read out from the pixel array  101 , where the upstream side is the vicinity of the wiring  122  connected to the TSV array  102 . That is, the ADC  17 A to which a pixel signal read out from the pixel array  101  is initially input is provided in the vicinity of the wiring  122  on the most upstream side, next the signal processor  13  is provided, and the DSP  14  is provided in a region farthest from the wiring  122 . Such a layout in which the ADC  17  to the DSP  14  are arranged from the upstream side along the flow of a signal can shorten the wiring connecting the parts. This layout leads to reduction in signal delay, reduction in signal propagation loss, improvement of the S/N ratio, and lower power consumption. 
     The controller  12  is provided, for example, in the vicinity of the wiring  122  on the upstream side. In  FIG. 4 , the controller  12  is provided between the ADC  17 A and the signal processor  13 . Such a layout leads to reduction in signal delay, reduction in signal propagation loss, improvement of the S/N ratio, and lower power consumption when the controller  12  controls the pixel array  101 . Advantageously, the signal pin and the power supply pin for analog circuits can be collectively arranged in the vicinity of the analog circuits (for example, in the lower side of  FIG. 4 ), the remaining signal pin and power supply pin for digital circuits can be collectively arranged in the vicinity of the digital circuits (for example, in the upper side of  FIG. 4 ), or the power supply pin for analog circuits and the power supply pin for digital circuits can be sufficiently spaced apart from each other. 
     In the layout illustrated in  FIG. 4 , the DSP  14  is provided on the side opposite to the ADC  17 A on the most downstream side. With such a layout, in other words, the DSP  14  can be provided in a region not overlapping with the pixel array  101  in the stacking direction of the first substrate  100  and the second substrate  120  (hereinafter simply referred to as top-bottom direction). 
     In this way, in the configuration in which the pixel array  101  and the DSP  14  are not superimposed in the top-bottom direction, intrusion of noise produced due to signal processing by the DSP  14  into the pixel array  101  can be reduced. As a result, even when the DSP  14  operates as a processing unit that performs computation based on a pre-trained model, intrusion of noise resulting from signal processing by the DSP  14  into the pixel array  101  can be reduced, and consequently, an image with less deterioration in quality can be acquired. 
     The DSP  14  and the signal processor  13  are connected by an interconnect  14   a  configured with a part of the DSP  14  or a signal line. The selector  16  is provided, for example, in the vicinity of the DSP  14 . When the interconnect  14   a  is a part of the DSP  14 , the DSP  14  may partially overlap with the pixel array  101  in the top-bottom direction. However, even in such a case, compared with when the whole of the DSP  14  is superimposed on the pixel array  101  in the top-bottom direction, intrusion of noise into the pixel array  101  can be reduced. 
     Memories  15 A and  15 B are arranged, for example, so as to surround the DSP  14  from three directions. In such an arrangement of the memories  15 A and  15 B surrounding the DSP  14 , the distance of wiring between each memory element in the memory  15  and the DSP  14  can be averaged while the distance can be reduced as a whole. Consequently, signal delay, signal propagation loss, and power consumption can be reduced when the DSP  14  accesses the memory  15 . 
     The pad array  123  is provided, for example, at a position on the second substrate  120  corresponding to the pad array  103  of the first substrate  100  in the top-bottom direction. Here, among the pads included in the pad array  123 , a pad positioned in the vicinity of the ADC  17 A is used for propagation of power supply voltage for analog circuits (mainly the ADC  17 A) or an analog signal. On the other hand, a pad positioned in the vicinity of the controller  12 , the signal processor  13 , the DSP  14 , or the memories  15 A and  15 B is used for propagation of power supply voltage for digital circuits (mainly, the controller  12 , the signal processor  13 , the DSP  14 , the memories  15 A and  15 B) and a digital signal. Such a pad layout can reduce the distance of wiring connecting the pads to the parts. This layout leads to reduction in signal delay, reduction in propagation loss of signals and power supply voltage, improvement of the S/N ratio, and lower power consumption. 
     1.4.2 Second Layout Example 
     A second layout example will now be described. In the second layout example, the layout example of the first substrate  100  may be similar to the layout example described with reference to  FIG. 3  in the first layout example. 
       FIG. 5  is a diagram illustrating a layout example of the second substrate in the second layout example. As illustrated in  FIG. 5 , in the second layout example, in a layout similar to the first layout example, the DSP  14  is provided at the center of a region in which the DSP  14  and the memory  15  are arranged. In other words, in the second layout example, the memory  15  is provided so as to surround the DSP  14  from four directions. 
     In such an arrangement of the memories  15 A and  15 B surrounding the DSP  14  from four directions, the distance of wiring between each memory element in the memory  15  and the DSP  14  can be further averaged while the distance can be further reduced as a whole. Consequently, signal delay, signal propagation loss, and power consumption can be further reduced when the DSP  14  accesses the memory  15 . 
     In  FIG. 5 , the DSP  14  and the pixel array  101  are arranged so as not to be superimposed on each other in the top-bottom direction. However, the present invention is not limited thereto, and the DSP  14  may be partially superimposed on the pixel array  101  in the top-bottom direction. Even in such a case, compared with when the whole of the DSP  14  is superimposed on the pixel array  101  in the top-bottom direction, intrusion of noise into the pixel array  101  can be reduced. 
     The other layout may be similar to the first layout example and is not further elaborated here. 
     1.4.3 Third Layout Example 
     A third layout example will now be described. In the third layout example, the layout example of the first substrate  100  may be similar to the layout example described with reference to  FIG. 3  in the first layout example. 
       FIG. 6  is a diagram illustrating a layout example of the second substrate in the third layout example. As illustrated in  FIG. 6 , in the third layout example, in a layout similar to the first layout example, the DSP  14  is provided adjacent to the signal processor  13 . In such a configuration, the signal line from the signal processor  13  to the DSP  14  can be shortened. This layout leads to reduction in signal delay, reduction in propagation loss of signals and power supply voltage, improvement of the S/N ratio, and lower power consumption. 
     In the third layout example, the memory  15  is provided so as to surround the DSP  14  from three directions. Consequently, signal delay, signal propagation loss, and power consumption can be reduced when the DSP  14  accesses the memory  15 . 
     In the third layout example, the DSP  14  is partially superimposed on the pixel array  101  in the top-bottom direction. Even in such a case, compared with when the whole of the DSP  14  is superimposed on the pixel array  101  in the top-bottom direction, intrusion of noise into the pixel array  101  can be reduced. 
     The other layout may be similar to the other layout examples and is not further elaborated here. 
     1.4.4 Fourth Layout Example 
     A fourth layout example will now be described. In the fourth layout example, the layout example of the first substrate  100  may be similar to the layout example described with reference to  FIG. 3  in the first layout example. 
       FIG. 7  is a diagram illustrating a layout example of the second substrate in the fourth layout example. As illustrated in  FIG. 7 , in the fourth layout example, in a layout similar to the third layout example, that is, in a layout in which the DSP  14  is provided adjacent to the signal processor  13 , the DSP  14  is provided at a position far from both of two TSV arrays  102 . 
     In such an arrangement of the DSP  14  at a position far from both of two TSV arrays  102 , because the ADC  17 A to the DSP  14  can be provided more faithfully to the signal flow, the signal line from the signal processor  13  to the DSP  14  can be further shortened. As a result, signal delay, signal propagation loss, and power consumption can be further reduced. 
     In the fourth layout example, the memory  15  is provided so as to surround the DSP  14  from two directions. Consequently, signal delay, signal propagation loss, and power consumption can be reduced when the DSP  14  accesses the memory  15 . 
     Also in the fourth layout example, the DSP  14  is partially superimposed on the pixel array  101  in the top-bottom direction. Even in such a case, compared with when the whole of the DSP  14  is superimposed on the pixel array  101  in the top-bottom direction, intrusion of noise into the pixel array  101  can be reduced. 
     The other layout may be similar to the other layout examples and is not further elaborated here. 
     1.4.5 Fifth Layout Example 
     A fifth layout example will now be described. In the fifth layout example, the layout example of the first substrate  100  may be similar to the layout example described with reference to  FIG. 3  in the first layout example. 
       FIG. 8  is a diagram illustrating a layout example of the second substrate in the fifth layout example. As illustrated in  FIG. 8 , in the fifth layout example, in a layout similar to the first layout example, that is, in a layout in which the DSP  14  is provided on the most downstream side, the DSP  14  is provided at a position far from both of two TSV arrays  102 . 
     Even in such a layout, because the ADC  17 A to the DSP  14  can be arranged more faithfully to the signal flow, the signal line from the signal processor  13  to the DSP  14  can be further shortened. As a result, signal delay, signal propagation loss, and power consumption can be further reduced. 
     The other layout may be similar to the other layout examples and is not further elaborated here. 
     1.4.6 Sixth Layout Example 
     A sixth layout example will now be described. In the sixth layout example, the layout example of the first substrate  100  may be similar to the layout example described with reference to  FIG. 3  in the first layout example. 
       FIG. 9  is a diagram illustrating a layout example of the second substrate in the sixth layout example. As illustrated in  FIG. 9 , in the sixth layout example, the DSP  14  is sandwiched in the top-bottom direction in the drawing between memories  15 C and  15 D divided into two regions. 
     In such an arrangement of the memories  15 C and  15 D sandwiching the DSP  14 , the distance of wiring between each memory element in the memory  15  and the DSP  14  can be averaged while the distance can be reduced as a whole. Consequently, signal delay, signal propagation loss, and power consumption can be further reduced when the DSP  14  accesses the memory  15 . 
     The other layout may be similar to the first layout example and is not further elaborated here. 
     1.4.7 Seventh Layout Example 
     A seventh layout example will now be described. In the seventh layout example, the layout example of the first substrate  100  may be similar to the layout example described with reference to  FIG. 3  in the first layout example. 
       FIG. 10  is a diagram illustrating a layout example of the second substrate in the seventh layout example. As illustrated in  FIG. 10 , in the seventh layout example, the memory  15  is sandwiched in the top-bottom direction in the drawing between DSPs  14 A and  14 B divided into two regions. 
     In such an arrangement of the DSPs  14 A and  14 B sandwiching the memory  15 , the distance of wiring between each memory element in the memory  15  and the DSP  14  can be averaged while the distance can be reduced as a whole. Consequently, signal delay, signal propagation loss, and power consumption can be further reduced when the DSP  14  accesses the memory  15 . 
     The other layout may be similar to the first layout example and is not further elaborated here. 
     1.4.8 Eighth Layout Example 
     An eighth layout example will now be described. In the eighth layout example, the layout example of the first substrate  100  may be similar to the layout example described with reference to  FIG. 3  in the first layout example. 
       FIG. 11  is a diagram illustrating a layout example of the second substrate in the eighth layout example. As illustrated in  FIG. 11 , in the eighth layout example, the DSP  14  is sandwiched in the left-right direction in the drawing between memories  15 E and  15 F divided into two regions. 
     In such an arrangement of the memories  15 C and  15 D sandwiching the DSP  14 , the distance of wiring between each memory element in the memory  15  and the DSP  14  can be averaged while the distance can be reduced as a whole. Consequently, signal delay, signal propagation loss, and power consumption can be further reduced when the DSP  14  accesses the memory  15 . 
     The other layout may be similar to the first layout example and is not further elaborated here. 
     1.4.9 Ninth Layout Example 
     A ninth layout example will now be described. In the ninth layout example, the layout example of the first substrate  100  may be similar to the layout example described with reference to  FIG. 3  in the first layout example. 
       FIG. 12  is a diagram illustrating a layout example of the second substrate in the ninth layout example. As illustrated in  FIG. 12 , in the ninth layout example, the memory  15  is sandwiched in the left-right direction in the drawing between DSPs  14 C and  14 D divided into two regions. 
     In such an arrangement of the DSPs  14 C and  14 D sandwiching the memory  15 , the distance of wiring between each memory element in the memory  15  and the DSP  14  can be averaged while the distance can be reduced as a whole. Consequently, signal delay, signal propagation loss, and power consumption can be further reduced when the DSP  14  accesses the memory  15 . 
     The other layout may be similar to the first layout example and is not further elaborated here. 
     1.5 Operation Effects 
     As described above, according to the present embodiment, the positional relation between the pixel array  101  and the DSP  14  is adjusted such that at least a part of the DSP  14  of the second substrate  120  is not superimposed on the pixel array  101  in the stacking direction (the top-bottom direction) of the first substrate  100  and the second substrate  120 . This configuration can reduce intrusion of noise resulting from signal processing by the DSP  14  into the pixel array  101  and therefore can provide an image with less deteriorated quality even when the DSP  14  operates as a processing unit that performs computation based on a pre-trained model. 
     2. Second Embodiment 
     A second embodiment will now be described in detail with reference to the drawings. In the following description, a configuration similar to the first embodiment is denoted by the same reference sign and an overlapping description thereof is omitted. 
     An imaging device as an electronic device according to the second embodiment may be similar to, for example, the imaging device  1  described in the first embodiment with reference to  FIG. 1 , which is hereby referred to and will not be further elaborated. 
     2.1 Chip Configuration Example of Image Sensor Chip 
     An example of the chip configuration of an image sensor according to the present embodiment will now be described in detail below with reference to the drawings.  FIG. 13  is a layout diagram illustrating an overall configuration example of the first substrate in the image sensor according to the present embodiment.  FIG. 14  is a diagram illustrating a chip configuration example of the image sensor according to the present embodiment. 
     As illustrated in  FIG. 13  and  FIG. 14 , in the present embodiment, the size of a first substrate  200  is smaller than the size of the second substrate  120 . For example, the size of the first substrate  200  is reduced in accordance with the size of the pixel array  101 . With such size reduction of the first substrate  200 , many first substrates  200  can be fabricated from a single semiconductor wafer. Furthermore, the chip size of the image sensor  10  can be further reduced. 
     For the bonding between the first substrate  200  and the second substrate  120 , chip-on-chip (CoC) technology in which the first substrate  200  and the second substrate  120  are individually diced into chips and then bonded, or chip-on-wafer (CoW) technology in which the diced first substrate  200  is bonded to the second substrate  120  in a wafer state can be employed. 
     The layout of the first substrate  200  may be similar to, for example, the layout of the first substrate  100  illustrated in the first embodiment, excluding the upper portion. The layout of the second substrate  120  may be similar to, for example, the second substrate  120  illustrated in the first embodiment. The bonding place of the first substrate  200  to the second substrate  120  may be a position where at least a part of the pixel array  101  does not overlap the DSP  14  of the second substrate  120  in the top-bottom direction, in the same manner as in the first embodiment. 
     2.2 Operation Effects 
     As described above, even when the first substrate  200  is downsized in accordance with the size of the pixel array  101 , intrusion of noise resulting from signal processing by the DSP  14  into the pixel array  101  can be reduced, in the same manner as in the first embodiment. Consequently, an image with less deterioration in quality can be acquired even when the DSP  14  operates as a processing unit that performs computation based on a pre-trained model. The other configuration (including the layout example of the second substrate  120 ) and effects may be similar to those of the first embodiment and will not be further elaborated here. 
     3. Third Embodiment 
     A third embodiment will now be described in detail with reference to the drawings. In the following description, a configuration similar to the first or second embodiment is denoted by the same reference sign and an overlapping description thereof is omitted. 
     An imaging device as an electronic device according to the third embodiment may be similar to, for example, the imaging device  1  described in the first embodiment with reference to  FIG. 1 , which is hereby referred to and will not be further elaborated. 
     3.1 Chip Configuration Example of Image Sensor Chip 
     An example of the chip configuration of an image sensor according to the present embodiment will now be described in detail below with reference to the drawings.  FIG. 15  is a layout diagram illustrating an overall configuration example of the first substrate in the image sensor according to the present embodiment.  FIG. 16  is a layout diagram illustrating an overall configuration example of the second substrate in the image sensor according to the present embodiment.  FIG. 17  is a diagram illustrating a chip configuration example of the image sensor according to the present embodiment. 
     As illustrated in  FIG. 15  to  FIG. 17 , in the present embodiment, the size of a first substrate  300  is reduced in accordance with the size of the pixel array  101 . In the present embodiment, the size of a second substrate  320  is reduced to the same degree as the size of the first substrate  300 . With such a configuration, in the present embodiment, a surplus region of the first substrate  300  can be reduced, and the chip size of the image sensor  10  can be further reduced accordingly. 
     However, in the present embodiment, the pixel array  101  and the DSP  14  are superimposed on each other in the stacking direction of the first substrate  300  and the second substrate  320  (hereinafter simply referred to as top-bottom direction). Because of this, noise resulting from the DSP  14  may be superimposed on a pixel signal read out from the pixel array  101  in some cases and may reduce the quality of an image acquired by the image sensor  10 . 
     Then, in the present embodiment, the ADC  17 A and the DSP  14  are spaced apart from each other. Specifically, for example, the ADC  17 A is provided closer to one end L 321  of the second substrate  320 , while the DSP  14  is provided closer to an end L 322  on the side opposite to the end L 321  at which the ADC  17 A is disposed. 
     With such an arrangement, noise produced by intrusion of noise produced in the DSP  14  into the ADC  17 A can be reduced, thereby suppressing deterioration in quality of an image acquired by the image sensor  10 . The end L 321  proximate to the ADC  17 A may be an end on which the wiring  122  connected to the TSV array  102  is provided. 
     With such an arrangement, for example, the ADC  17 A, the signal processor  13 , and the DSP  14  are arranged in order from the upstream side along the flow of a signal read out from the pixel array  101 , where the upstream side is the vicinity of the wiring  122  connected to the TSV array  102 , in the same manner as in the foregoing embodiments. The wiring connecting the parts therefore can be shortened. Consequently, reduction in signal delay, reduction in signal propagation loss, improvement in the S/N ratio, and lower power consumption can be achieved. 
     3.2 Operation Effects 
     As described above, when the first substrate  300  and the second substrate  320  are downsized in accordance with the size of the pixel array  101 , the ADC  17 A and the DSP  14  are spaced apart from each other, thereby reducing noise produced by intrusion of noise produced in the DSP  14  into the ADC  17 A. Consequently, deterioration in quality of an image acquired by the image sensor  10  can be suppressed. 
     The other configuration and effects are similar to those of the foregoing embodiments and will not be further elaborated here. 
     4. Fourth Embodiment 
     In a fourth embodiment, a specific configuration example of the image sensor  10  and the imaging device  1  according to the foregoing embodiments and an attachment example thereof will be described. In the following description, an example based on the first embodiment is illustrated. However, the present embodiment may be based on any other embodiments rather than the first embodiment. In the present embodiment, the imaging device  1  is mounted on a vehicle, that is, the imaging device  1  is an in-vehicle camera, by way of example. However, the imaging device  1  is not necessarily attached to a vehicle but may be attached to various equipment, devices, and locations. 
     4.1 Configuration Example 
       FIG. 18  is a diagram illustrating an overall configuration example of an imaging device according to the present embodiment. In  FIG. 18 , for simplicity of explanation, the first substrate  100  in the image sensor  10  is not illustrated. 
     As illustrated in  FIG. 18 , the chip of the image sensor  10  according to the foregoing embodiments may be connected to a circuit board  400  provided with the application processor  20  and the like, for example, through connection wiring that is flexible and deformable, such as a flexible cable  401 . 
     In this case, one end of the flexible cable  402  may be connected to a side other than the side on which the ADC  17 A in the second substrate  120  is provided in proximity, for example, to the side on which the DSP  14  is provided in proximity. This configuration can reduce the wiring length from a data output end in the DSP  14  or the memory  15  provided in vicinity thereof to the flexible cable  402 , thereby suppressing size increase of the chip of the image sensor  10  and facilitating designing of this wiring layout. Reducing the wiring length can lead to suppression of signal delay, reduction in signal propagation loss, and lower power consumption. 
     4.2 Attachment Example 
     Some of attachment examples of the imaging device  1  according to the present embodiment will now be described. 
     4.2.1 First Example 
     First, an attachment example in which the imaging device  1  is mounted as a front camera for capturing an image in front of a vehicle will be described as a first example.  FIG. 19  is a diagram illustrating an attachment example of the imaging device according to the first example of the present embodiment. 
     As illustrated in  FIG. 19 , when the imaging device  1  is mounted as a front camera on a vehicle  410 , the imaging device  1  is provided, for example, in the vicinity of a windshield  411  inside the vehicle  410 , at a location that does not interrupt the field of view of a driver D. 
     In a state in which the imaging device  1  is attached to the inside of the vehicle  410 , the image sensor  10  is inclined at about 90° to the front direction of the vehicle  410 , for example, such that a light-receiving surface of the pixel array  101  of the first substrate  100  faces substantially the front side of the vehicle  410 . On the other hand, the circuit board  400  connected to the image sensor  10  through the flexible cable  402  is installed, for example, such that its main plane is substantially horizontal. The main plane of the circuit board  400  may be, for example, a surface parallel to the surface provided with an electronic circuit such as the application processor  20 . As used herein the horizontal direction may be a horizontal direction in the interior space of the vehicle  410 . 
     The image sensor  10  and the circuit board  400  may be arranged, for example, such that the circuit board  400  is positioned below the image sensor  10  and at least the front-side end of the circuit board  400  protrudes toward the front direction of the vehicle relative to the front-side end of the image sensor  10 . Thus, the imaging device  1  can be provided in closer proximity to the windshield  411  inclined toward the front direction of the vehicle  410 , so that the space occupied by the imaging device  1  can be reduced. 
     In this case, the respective end portions of the image sensor  10  and the circuit board  400  are arranged in proximity to each other so as to form the L shape, and the end portions arranged in proximity to each other are connected by the flexible cable  402 , whereby the length of the flexible cable  402  can be reduced. 
     In such an arrangement example, for example, when the flexible cable  402  is connected to the end on which the DSP  14  is provided in proximity in the second substrate  120 , the image sensor  10  is installed such that the ADC  17 A in the second substrate  120  is positioned on the upper side in the vertical direction and the DSP  14  is positioned on the lower side in the vertical direction. The flexible cable  402  is attached so as to connect the lower-side end of the image sensor  10  and the rear-side end of the circuit board  400 . Furthermore, the application processor  20  in the circuit board  400  is provided, for example, on the front side of the vehicle  410  relative to the image sensor 
     4.2.2 Second Example 
     Next, an attachment example in which the imaging device  1  is mounted as a rear camera for capturing an image behind a vehicle will be described as a second example.  FIG. 20  is a diagram illustrating an installation example of the imaging device according to the second example of the present embodiment. 
     As illustrated in  FIG. 20 , when the imaging device  1  is mounted as a rear camera on the vehicle  410 , the imaging device  1  is provided, for example, in the vicinity of a rear window  412  inside the vehicle  410 , at a location that does not interrupt the field of view of a driver D through a rearview mirror. 
     In a state in which the imaging device  1  is attached to the inside of the vehicle  410 , the image sensor  10  is inclined at about 90° to the rear direction of the vehicle  410 , for example, such that the light-receiving surface of the pixel array  101  of the first substrate  100  faces substantially the rear side of the vehicle  410 . On the other hand, the circuit board  400  connected to the image sensor  10  through the flexible cable  402  is installed, for example, such that its main plane is substantially parallel to the light-receiving surface of the image sensor  10 . The flexible cable  402  may connect the upper ends of the image sensor  10  and the circuit board  400  in the installed state, or may connect the lower ends thereof, or may connect the side ends thereof. 
     However, the embodiment is not limited to such an attachment example. Even when the imaging device  1  is installed as a rear camera, the image sensor  10  and the circuit board  400  may be arranged, for example, such that the circuit board  400  is positioned below the image sensor  10  and at least the rear-side end of the circuit board  400  protrudes to the rear direction of the vehicle relative to the rear-side end of the image sensor  10 , similarly to when the imaging device  1  is installed as a front camera in the first example. Thus, the imaging device  1  can be provided in closer proximity to the rear window  412  inclined toward the rear direction of the vehicle  410 , so that the space occupied by the imaging device  1  can be reduced. 
     4.3 Operation Effects 
     As described above, in the present embodiment, one end of the flexible cable  402  is connected to a side other than the side on which the ADC  17 A in the second substrate  120  is provided in proximity, for example, to the side on which the DSP  14  is provided in proximity. This configuration can reduce the wiring length from a data output end in the DSP  14  or the memory  15  provided in vicinity thereof to the flexible cable  402 , thereby suppressing size increase of the chip of the image sensor  10  and facilitating designing of this wiring layout. Reducing the wiring length can lead to suppression of signal delay, reduction in signal propagation loss, and lower power consumption. 
     The image sensor  10  and the circuit board  400  are not necessarily connected by a flexible and deformable connection cable, such as the flexible cable  402 , as described above but may be connected using a connection part that does not have flexibility, such as solder balls, bonding pads, and connection pins. 
     Other configurations and effects may be similar to those in the foregoing embodiments and will not be further elaborated here. 
     5. Application to Other Sensors 
     In the foregoing embodiments, the technique according to the present disclosure is applied to a solid-state imaging device (image sensor  10 ) that acquires a two-dimensional image. However, the application of the technique according to the present disclosure is not limited to a solid-state imaging device. For example, the technique according to the present disclosure can be applied to a variety of light-receiving sensors such as Time of Flight (ToF) sensors, infrared (IR) sensors, and dynamic vision sensors (DVS). That is, when the chip structure of light-receiving sensors is of the stacked type, reduction of noise included in sensor results and miniaturization of sensor chips can be achieved. 
     6. Application to Movable Body 
     The technique according to the present disclosure (the present technique) is applicable to a variety of products. For example, the technique according to the present disclosure may be implemented as a device mounted on any type of movable bodies, such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, vessels and ships, and robots. 
       FIG. 21  is a block diagram illustrating an example of the overall configuration of a vehicle control system that is an example of a movable body control system to which the technique according to the present disclosure is applicable. 
     A vehicle control system  12000  includes a plurality of electronic control units connected through a communication network  12001 . In the example illustrated in  FIG. 21 , the vehicle control system  12000  includes a drive control unit  12010 , a body control unit  12020 , a vehicle exterior information detection unit  12030 , a vehicle interior information detection unit  12040 , and a central control unit  12050 . As a functional configuration of the central control unit  12050 , a microcomputer  12051 , a sound image output module  12052 , and an in-vehicle network I/F (interface)  12053  are illustrated. 
     The drive control unit  12010  controls operation of devices related to a drive system of a vehicle in accordance with a variety of computer programs. For example, the drive control unit  12010  functions as a control device for a drive force generating device for generating drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating braking force of the vehicle. 
     The body control unit  12020  controls operation of a variety of devices installed in the vehicle body in accordance with a variety of computer programs. For example, the body control unit  12020  functions as a control device for a keyless entry system, a smart key system, a power window device, or a variety of lamps such as head lamps, rear lamps, brake lamps, turn signals, and fog lamps. In this case, the body control unit  12020  may receive radio waves transmitted from a portable device alternative to a key or signals from a variety of switches. The body control unit  12020  accepts input of the radio waves or signals and controls a door lock device, a power window device, a lamp, and the like of the vehicle. 
     The vehicle exterior information detection unit  12030  detects information on the outside of the vehicle equipped with the vehicle control system  12000 . For example, an imager  12031  is connected to the vehicle exterior information detection unit  12030 . The vehicle exterior information detection unit  12030  allows the imager  12031  to capture an image of the outside of the vehicle and receives the captured image. The vehicle exterior information detection unit  12030  may perform an object detection process or a distance detection process for persons, vehicles, obstacles, signs, or characters on roads, based on the received image. 
     The imager  12031  is an optical sensor that receives light and outputs an electrical signal corresponding to the quantity of received light of the light. The imager  12031  may output an electrical signal as an image or output as information on a measured distance. Light received by the imager  12031  may be visible light or invisible light such as infrared rays. 
     The vehicle interior information detection unit  12040  detects information on the inside of the vehicle. The vehicle interior information detection unit  12040  is connected to, for example, a driver state detector  12041  that detects a state of the driver. The driver state detector  12041  includes, for example, a camera for taking an image of the driver, and the vehicle interior information detection unit  12040  may calculate the degree of fatigue or the degree of concentration of the driver or may determine whether the driver falls asleep, based on detection information input from the driver state detector  12041 . 
     The microcomputer  12051  can compute a control target value for the drive force generating device, the steering mechanism, or the braking device, based on information on the inside and outside of the vehicle acquired by the vehicle exterior information detection unit  12030  or the vehicle interior information detection unit  12040 , and output a control command to the drive control unit  12010 . For example, the microcomputer  12051  can perform coordination control for the purpose of function implementation of advanced driver assistance systems (ADAS), including collision avoidance or shock mitigation of the vehicle, car-following drive based on the distance between vehicles, vehicle speed-keeping drive, vehicle collision warning, or lane departure warning. 
     The microcomputer  12051  can perform coordination control for the purpose of, for example, autonomous driving, in which the drive force generating device, the steering mechanism, or the braking device is controlled based on information on the surroundings of the vehicle acquired by the vehicle exterior information detection unit  12030  or the vehicle interior information detection unit  12040  to enable autonomous driving without depending on the operation by the driver. 
     The microcomputer  12051  can output a control command to the body control unit  12020 , based on information on the outside of the vehicle acquired by the vehicle exterior information detection unit  12030 . For example, the microcomputer  12051  can perform coordination control for the antidazzle purpose, for example, by controlling the head lamps in accordance with the position of a vehicle ahead or an oncoming vehicle detected by the vehicle exterior information detection unit  12030  to switch high beams to low beams. 
     The sound image output module  12052  transmits an output signal of at least one of sound and image to an output device capable of visually or aurally giving information to a passenger in the vehicle or the outside of the vehicle. In the example in  FIG. 21 , an audio speaker  12061 , a display  12062 , and an instrument panel  12063  are illustrated as the output device. The display  12062  may include, for example, at least one of an on-board display and a head-up display. 
       FIG. 22  is a diagram illustrating an example of the installation position of the imager  12031 . 
     In  FIG. 22 , imagers  12101 ,  12102 ,  12103 ,  12104 , and  12105  are provided as the imager  12031 . 
     The imagers  12101 ,  12102 ,  12103 ,  12104 , and  12105  are provided, for example, at positions such as front nose, side mirrors, rear bumper, back door of a vehicle  12100 , and an upper portion of the front glass inside the vehicle. The imager  12101  provided at the front nose and the imager  12105  provided at the upper portion of the front glass inside the vehicle mainly acquire an image in front of the vehicle  12100 . The imagers  12102  and  12103  provided at the side mirrors mainly acquire images on the sides of the vehicle  12100 . The imager  12104  provided at the rear bumper or the back door mainly acquires an image behind the vehicle  12100 . The imager  12105  provided at the upper portion of the front glass in the vehicle interior is mainly used for detecting a vehicle ahead, pedestrians, obstacles, traffic signs, road signs, traffic lanes, and the like. 
       FIG. 22  illustrates an example of the imaging ranges of the imagers  12101  to  12104 . An imaging range  12111  indicates the imaging range of the imager  12101  provided at the front nose, imaging ranges  12112  and  12113  indicate the imaging ranges of the imagers  12102  and  12103  provided at the side mirrors, and an imaging range  12114  indicates the imaging range of the imager  12104  provided at the rear bumper or the back door. For example, a bird&#39;s eye view of the vehicle  12100  viewed from above can be obtained by superimposing image data captured by the imagers  12101  to  12104 . 
     At least one of the imagers  12101  to  12104  may have a function of acquiring distance information. For example, at least one of the imagers  12101  to  12104  may be a stereo camera including a plurality of image sensors or may be an image sensor having a pixel for phase difference detection. 
     For example, the microcomputer  12051  can obtain the distance to a three-dimensional object within the imaging ranges  12111  to  12114  and a temporal change of this distance (relative speed to the vehicle  12100 ), based on distance information obtained from the imagers  12101  to  12104 , to specifically extract a three-dimensional object closest to the vehicle  12100  on the path of travel and traveling at a predetermined speed (for example, 0 km/h or more) in substantially the same direction as the vehicle  12100 , as a vehicle ahead. In addition, the microcomputer  12051  can preset a distance between vehicles to be kept behind a vehicle ahead and perform, for example, automatic braking control (including car-following stop control) and automatic speed-up control (including car-following startup control). In this way, coordination control can be performed for the purpose of, for example, autonomous driving in which the vehicle runs autonomously without depending on the operation by the driver. 
     For example, the microcomputer  12051  can classify three-dimensional object data on a three-dimensional object into “two-wheel vehicle”, “standard-sized vehicle”, “heavy vehicle”, “pedestrian”, “utility pole”, or “any other three-dimensional object”, based on the distance information obtained from the imagers  12101  to  12104  and extract the data, and can use the extracted data for automatic avoidance of obstacles. For example, the microcomputer  12051  identifies an obstacle in the surroundings of the vehicle  12100  as an obstacle visible to the driver of the vehicle  12100  or as an obstacle hardly visible. The microcomputer  12051  then determines a collision risk indicating the degree of risk of collision with each obstacle and, when the collision risk is equal to or higher than a setting value and there is a possibility of collision, outputs an alarm to the driver through the audio speaker  12061  or the display  12062 , or performs forced deceleration or avoidance steering through the drive control unit  12010 , thereby implementing drive assistance for collision avoidance. 
     At least one of the imagers  12101  to  12104  may be an infrared camera that detects infrared rays. For example, the microcomputer  12051  can recognize a pedestrian by determining whether a pedestrian exists in the image captured by the imagers  12101  to  12104 . Such recognition of pedestrians is performed, for example, through the procedure of extracting feature points in the image captured by the imagers  12101  to  12104  serving as an infrared camera and the procedure of performing pattern matching with a series of feature points indicating the outline of an object to determine whether the object is a pedestrian. When the microcomputer  12051  determines that a pedestrian exists in the image captured by the imagers  12101  to  12104  and recognizes a pedestrian, the sound image output module  12052  controls the display  12062  such that a rectangular outline for highlighting the recognized pedestrian is superimposed. The sound image output module  12052  may control the display  12062  such that an icon indicating a pedestrian appears at a desired position. 
     An example of the vehicle control system to which the technique according to the present disclosure is applicable has been described above. The technique according to the present disclosure is applicable to the imager  12031  and the like in the configuration described above. When the technique according to the present disclosure is applied to the imager  12031  and the like, miniaturization of the imager  12031  and the like can be achieved, thereby facilitating design of the interior and the exterior of the vehicle  12100 . When the technique according to the present disclosure is applied to the imager  12031  and the like, a clear image with reduced noise can be acquired to provide a driver with a more visible image. Consequently, the driver&#39;s fatigue can be alleviated. 
     7. Application to Endoscopic Surgery System 
     The technique according to the present disclosure (the present technique) is applicable to a variety of products. For example, the technique according to the present disclosure may be applied to an endoscopic surgery system. 
       FIG. 23  is a diagram illustrating an example of the overall configuration of an endoscopic surgery system to which the technique according to the present disclosure (the present technique) is applicable. 
       FIG. 23  illustrates a situation in which an operator (doctor)  11131  uses an endoscopic surgery system  11000  to perform an operation on a patient  11132  on a patient bed  11133 . As illustrated in the drawing, the endoscopic surgery system  11000  includes an endoscope  11100 , other surgical instruments  11110  such as an insufflation tube  11111  and an energy treatment tool  11112 , a support arm device  11120  supporting the endoscope  11100 , and a cart  11200  carrying a variety of devices for endoscopic surgery. 
     The endoscope  11100  includes a barrel  11101  having a region of a predetermined length from its tip end to be inserted into the body cavity of the patient  11132 , and a camera head  11102  connected to the base end of the barrel  11101 . In the example illustrated in the drawing, the endoscope  11100  is a rigid borescope having a rigid barrel  11101 . However, the endoscope  11100  may be configured as a soft borescope having a soft barrel. 
     The tip end of the barrel  11101  has an opening having an objective lens fitted therein. A light source device  11203  is connected to the endoscope  11100 . Light generated by the light source device  11203  is propagated to the tip end of the barrel through a light guide extending inside the barrel  11101  and irradiates an observation target in the body cavity of the patient  11132  through the objective lens. The endoscope  11100  may be a forward-viewing endoscope or may be a forward-oblique viewing endoscope or a side-viewing endoscope. 
     An optical system and an image sensor are provided inside the camera head  11102 . Reflected light (observation light) from an observation target is collected by the optical system onto the image sensor. The observation light is converted to electricity by the image sensor to generate an electrical signal corresponding to the observation light, that is, an image signal corresponding to an observation image. The image signal is transmitted as RAW data to a camera control unit (CCU)  11201 . 
     The CCU  11201  is configured with a central processing unit (CPU), a graphics processing unit (GPU), or the like to centrally control the operation of the endoscope  11100  and a display device  11202 . The CCU  11201  receives an image signal from the camera head  11102  and performs a variety of image processing on the image signal, for example, a development process (demosaicing) for displaying an image based on the image signal. 
     The display device  11202  displays an image based on the image signal subjected to image processing by the CCU  11201 , under the control of the CCU  11201 . 
     The light source device  11203  is configured with, for example, a light source such as a light emitting diode (LED) and supplies the endoscope  11100  with radiation light in imaging a surgery site. 
     An input device  11204  is an input interface with the endoscopic surgery system  11000 . The user can input a variety of information and instructions to the endoscopic surgery system  11000  through the input device  11204 . For example, the user inputs an instruction to change the imaging conditions by the endoscope  11100  (the kind of radiation light, magnification, focal length, etc.). 
     A treatment tool control device  11205  controls actuation of the energy treatment tool  11112  for cauterization of tissues, incision, or sealing of blood vessels. An insufflator  11206  feeds gas into the body cavity through the insufflation tube  11111  to insufflate the body cavity of the patient  11132  in order to ensure the field of view with the endoscope  11100  and ensure a working space for the operator. A recorder  11207  is a device capable of recording a variety of information on surgery. A printer  11208  is a device capable of printing a variety of information on surgery in a variety of forms such as text, image, or graph. 
     The light source device  11203  that supplies the endoscope  11100  with radiation light in imaging a surgery site can be configured with, for example, a white light source such as an LED, a laser light source, or a combination thereof. When a white light source is configured with a combination of RGB laser light sources, the output power and the output timing of each color (each wavelength) can be controlled accurately, and, therefore, the white balance of the captured image can be adjusted in the light source device  11203 . In this case, an observation target is irradiated time-divisionally with laser light from each of the RGB laser light sources, and actuation of the image sensor in the camera head  11102  is controlled in synchronization with the radiation timing, whereby an image corresponding to each of R, G, and B can be captured time-divisionally. According to this method, a color image can be obtained even without color filters in the image sensor. 
     The actuation of the light source device  11203  may be controlled such that the intensity of output light is changed every certain time. In synchronization with the timing of changing the intensity of light, the actuation of the image sensor in the camera head  11102  is controlled to acquire images time-divisionally, and the images are combined to generate an image with a high dynamic range free from blocked-up shadows and blown out highlights. 
     The light source device  11203  may be configured to supply light in a predetermined wavelength band corresponding to specific light observation. In specific light observation, for example, narrow band imaging is performed, which uses the wavelength dependency of light absorption in body tissues and applies light in a narrow band, compared with radiation light (that is, white light) in normal observation, to capture a high-contrast image of predetermined tissues such as blood vessels in the outermost surface of mucosa. Alternatively, in specific light observation, fluorescence observation may be performed in which an image is acquired by fluorescence generated by radiation of excitation light. In fluorescence observation, for example, excitation light is applied to body tissues and fluorescence from the body tissues is observed (autofluorescence imaging), or a reagent such as indocyanine green (ICG) is locally injected to body tissues and excitation light corresponding to the fluorescence wavelength of the reagent is applied to the body tissues to obtain a fluorescence image. The light source device  11203  may be configured to supply narrow-band light and/or excitation light corresponding to such specific light observation. 
       FIG. 24  is a block diagram illustrating an example of the functional configuration of the camera head  11102  and the CCU  11201  illustrated in  FIG. 23 . 
     The camera head  11102  includes a lens unit  11401 , an imager  11402 , a driver  11403 , a communication module  11404 , and a camera head controller  11405 . The CCU  11201  includes a communication module  11411 , an image processor  11412 , and a controller  11413 . The camera head  11102  and the CCU  11201  are connected to communicate with each other through a transmission cable  11400 . 
     The lens unit  11401  is an optical system provided at a connection portion to the barrel  11101 . Observation light taken in from the tip end of the barrel  11101  is propagated to the camera head  11102  and enters the lens unit  11401 . The lens unit  11401  is configured with a combination of a plurality of lenses including a zoom lens and a focus lens. 
     The imager  11402  may be configured with one image sensor (called single sensor-type) or a plurality of image sensors (called multi sensor-type). When the imager  11402  is a multi-sensor construction, for example, image signals corresponding to R, G, and B may be generated by image sensors and combined to produce a color image. Alternatively, the imager  11402  may have a pair of image sensors for acquiring image signals for right eye and for left eye corresponding to three-dimensional (3D) display. The 3D display enables the operator  11131  to more accurately grasp the depth of living tissues in a surgery site. When the imager  11402  is a multi-sensor construction, several lines of lens units  11401  may be provided corresponding to the image sensors. 
     The imager  11402  is not necessarily provided in the camera head  11102 . For example, the imager  11402  may be provided immediately behind the objective lens inside the barrel  11101 . 
     The driver  11403  is configured with an actuator and moves the zoom lens and the focus lens of the lens unit  11401  by a predetermined distance along the optical axis under the control of the camera head controller  11405 . The magnification and the focal point of an image captured by the imager  11402  thus can be adjusted as appropriate. 
     The communication module  11404  is configured with a communication device for transmitting/receiving a variety of information to/from the CCU  11201 . The communication module  11404  transmits an image signal obtained from the imager  11402  as RAW data to the CCU  11201  through the transmission cable  11400 . 
     The communication module  11404  receives a control signal for controlling actuation of the camera head  11102  from the CCU  11201  and supplies the received signal to the camera head controller  11405 . The control signal includes, for example, information on imaging conditions, such as information specifying a frame rate of the captured images, information specifying an exposure value in imaging, and/or information specifying a magnification and a focal point of the captured image. 
     The image conditions such as frame rate, exposure value, magnification, and focal point may be specified as appropriate by the user or may be automatically set by the controller  11413  of the CCU  11201  based on the acquired image signal. In the latter case, the endoscope  11100  is equipped with an auto exposure (AE) function, an auto focus (AF) function, and an auto white balance (AWB) function. 
     The camera head controller  11405  controls actuation of the camera head  11102 , based on a control signal received from the CCU  11201  through the communication module  11404 . 
     The communication module  11411  is configured with a communication device for transmitting/receiving a variety of information to/from the camera head  11102 . The communication module  11411  receives an image signal transmitted from the camera head  11102  through the transmission cable  11400 . 
     The communication module  11411  transmits a control signal for controlling actuation of the camera head  11102  to the camera head  11102 . The image signal and the control signal can be transmitted via electrical communication or optical communication. 
     The image processor  11412  performs a variety of image processing on the image signal that is RAW data transmitted from the camera head  11102 . 
     The controller  11413  performs a variety of control on imaging of a surgery site and the like by the endoscope  11100  and display of a captured image obtained by imaging of a surgery site and the like. For example, the controller  11413  generates a control signal for controlling actuation of the camera head  11102 . 
     The controller  11413  displays a captured image visualizing a surgery site and the like on the display device  11202 , based on the image signal subjected to image processing by the image processor  11412 . In doing so, the controller  11413  may recognize a variety of objects in the captured image using a variety of image recognition techniques. For example, the controller  11413  can detect the shape of edge, color, and the like of an object included in the captured image to recognize a surgical instrument such as forceps, a specific living body site, bleeding, and mist in use of the energy treatment tool  11112 . When displaying the captured image on the display device  11202 , the controller  11413  may use the recognition result to superimpose a variety of surgery assisting information on the image of the surgery site. The surgery assisting information superimposed and presented to the operator  11131  can alleviate burden on the operator  11131  or ensure the operator  11131  to proceed surgery. 
     The transmission cable  11400  connecting the camera head  11102  and the CCU  11201  is an electrical signal cable corresponding to communication of electrical signals, an optical fiber corresponding to optical communication, or a composite cable thereof. 
     In the example illustrated in the drawing, the transmission cable  11400  is used for wired communication. However, communication between the camera head  11102  and the CCU  11201  may be wireless. 
     An example of the endoscopic surgery system to which the technique according to the present disclosure is applicable has been described above. The technique according to the present disclosure is applicable to, for example, the imager  11402  and the like in the camera head  11102  among the configurations described above. When the technique according to the present disclosure is applied to the camera head  11102 , the camera head  11102  and the like can be miniaturized, resulting in the compact endoscopic surgery system  11000 . When the technique according to the present disclosure is applied to the camera head  11102  and the like, a clear image with reduced noise can be acquired to provide the operator with a more visible image. Consequently, the operator&#39;s fatigue can be alleviated. 
     Although the endoscopic surgery system has been described here by way of example, the technique according to the present disclosure may be applied to, for example, a microscopic surgery system. 
     8. Application to Whole Slide Imaging (WSI) System 
     The technique according to the present disclosure is applicable to a variety of products. For example, the technique according to the present disclosure may be applied to a pathology diagnosis system to allow doctors to diagnose pathological changes by observing cells and tissues sampled from patients, and an assistance system therefor (hereinafter referred to as diagnostic assistance system). This diagnostic assistance system may be a whole slide imaging (WSI) system for diagnosing pathological changes based on an image acquired using digital pathology technology, and assisting the diagnosis. 
       FIG. 25  is a diagram illustrating an example of the overall configuration of a diagnostic assistance system  5500  to which the technique according to the present disclosure is applied. As illustrated in  FIG. 25 , the diagnostic assistance system  5500  includes one or more pathology systems  5510 . The diagnostic assistance system  5500  may further include a medical information system  5530  and a derivation device  5540 . 
     Each of one or more pathology systems  5510  is a system mainly used by pathologists and introduced into, for example, a research laboratory or a hospital. The pathology systems  5510  may be introduced into different hospitals and are connected to the medical information system  5530  and the derivation device  5540  through a variety of networks such as wide area networks (WANs) (including the Internet), local area networks (LAN), public networks, and mobile communication networks. 
     Each pathology system  5510  includes a microscope  5511 , a server  5512 , a display control device  5513 , and a display device  5514 . 
     The microscope  5511  has the function of an optical microscope and captures an image of an observation target on a glass slide to acquire a pathological image that is a digital image. The observation target is, for example, tissues or cells sampled from a patient and may be a piece of organ, saliva, or blood. 
     The server  5512  stores and saves the pathological image acquired by the microscope  5511  in a not-illustrated storage unit. When accepting an inspection request from the display control device  5513 , the server  5512  searches the not-illustrated storage unit for a pathological image and sends the retrieved pathological image to the display control device  5513 . 
     The display control device  5513  sends an inspection request for a pathological image accepted from the user to the server  5512 . The display control device  5513  then displays the pathological image accepted from the server  5512  on the display device  5514  using liquid crystal, electro-luminescence (EL), cathode ray tube (CRT), or the like. The display device  5514  may support  4 K or  8 K, and one or more display devices  5514  may be provided. 
     Here, when the observation target is a solid matter such as a piece of organ, the observation target may be, for example, a stained slice. The slice may be prepared, for example, by slicing a block cut out from a specimen such as an organ. When sliced, the block may be fixed by, for example, paraffin. 
     In staining the slice, a variety of staining can be employed, such as common staining such as hematoxylin-eosin (HE) staining for defining the form of tissue, and immunostaining such as immunohistochemistry (IHC) staining for identifying the immune state of tissue. In doing so, one slice may be stained using different kinds of reagents, or two or more slices (also referred to as adjacent slices) continuously cut out from the same block may be stained using different reagents. 
     The microscope  5511  may include a low-resolution imager for capturing an image at low resolution and a high-resolution imager for capturing an image at high resolution. The low-resolution imager and the high-resolution imager may be different optical systems or the same optical system. In the case of the same optical system, the microscope  5511  may have a resolution changed according to an imaging target. 
     A glass slide having an observation target is placed on a stage positioned in the angle of view of the microscope  5511 . The microscope  5511  first acquires the entire image in the angle of view using the low-resolution imager and specifies the region of the observation target from the acquired entire image. Subsequently, the microscope  5511  divides the region including the observation target into a plurality of division regions with a predetermined size and successively captures images of the division regions using the high-resolution imager to acquire high-resolution images of the division regions. In switching the target division regions, the stage may be moved, the imaging optical system may be moved, or both may be moved. Each division region may be overlapped with the adjacent division region in order to prevent occurrence of an imaging-missed region due to unintended slippage of the glass slide. The entire image may include identification information for associating the entire image with the patient. Examples of the identification information include a character string and a QR code (registered trademark). 
     The high-resolution images acquired by the microscope  5511  are input to the server  5512 . The server  5512  divides each high-resolution image into partial images (hereinafter referred to as tile images) with a smaller size. For example, the server  5512  vertically and horizontally divides one high-resolution image into 10×10, in total, 100 tile images. In doing so, if adjacent division regions are overlapping, the server  5512  may perform a stitching process for the high-resolution images adjacent to each other using such technology as template matching. In this case, the server  5512  may divide the stitched high-resolution images as a whole to generate tile images. However, the generation of tile images from a high-resolution image may precede the stitching process. 
     The server  5512  may further divide a tile image to generate tile images with a smaller size. The generation of such tile images may be repeated until a tile image set as a minimum unit is generated. 
     Upon generating a tile image as a minimum unit, the server  5512  executes a tile combining process for all the tile images to combine a predetermined number of adjacent tile images and generate one tile image. This tile combining process may be repeated until finally one tile image is generated. Through such a process, a tile image group having a pyramid structure is generated, in which each layer is configured with one or more tile images. In this pyramid structure, a tile image on a certain layer and a tile image on a layer different from this layer have the same pixel count, but their resolutions are different. For example, when 2×2, in total, four tile images are combined into one tile image on a higher layer, the resolution of the tile image on the higher layer is half the resolution of the tile images on the lower layer used in combining. 
     When such a tile image group having a pyramid structure is constructed, the level of detail of the observation target appearing on the display device can be changed according to the layer to which a tile image to be displayed belongs to. For example, when the tile image on the lowest layer is used, a narrow region of the observation target can be displayed in detail, and as the tile image on a higher layer is used, a wide region of the observation target can be displayed more coarsely. 
     The generated tile image group having a pyramid structure is, for example, stored in a not-illustrated storage unit together with identification information uniquely identifying each tile image (referred to as tile identification information). When accepting an acquisition request for a tile image including tile identification information from another device (for example, the display control device  5513  or the derivation device  5540 ), the server  5512  transmits the tile image corresponding to the tile identification information to another device. 
     The tile image that is a pathological image may be generated for each imaging condition such as focal length and staining condition. When a tile image is generated for each imaging condition, a certain pathological image as well as another pathological image corresponding to an imaging condition different from a certain imaging condition and in the same region as the certain pathological image may be displayed side by side. The certain imaging condition may be designated by an inspector. When the inspector designates a plurality of imaging conditions, pathological images in the same region corresponding to the respective imaging conditions may be displayed side by side. 
     The server  5512  may store the tile image group having a pyramid structure in a storage device other than the server  5512 , for example, a cloud server. A part or the whole of the tile image generating process as described above may be performed, for example, by a cloud server. 
     The display control device  5513  extracts a desired tile image from the tile image group having a pyramid structure in accordance with input operation from the user and outputs the same to the display device  5514 . Through such a process, the user can attain a sense of viewing the observation target while changing the observation magnification. That is, the display control device  5513  functions as a virtual microscope. The virtual observation magnification here actually corresponds to a resolution. 
     High-resolution images can be captured by any methods. A high-resolution image may be acquired by capturing images of division regions while the stage is repeatedly stopped and moved, or a high-resolution image on a strip may be acquired by capturing images of division regions while the stage is moved at a predetermined speed. The process of generating tile images from a high-resolution image is not an essential configuration, and the resolution of the stitched high-resolution images as a whole may be changed stepwise to generate an image with resolution changing stepwise. Also in this case, a low-resolution image in a wide area to a high-resolution image in a narrow area can be presented stepwise to the user. 
     The medical information system  5530  is an electronic health record system and stores information related to diagnosis, such as information identifying patients, disease information of patients, examination information and image information used in diagnosis, diagnosis results, and prescribed drugs. For example, a pathological image obtained by imaging an observation target of a patient may be saved once through the server  5512  and thereafter displayed on the display device  5514  by the display control device  5513 . The pathologist using the pathology system  5510  conducts pathology diagnosis based on the pathological image appearing on the display device  5514 . The result of pathology diagnosis conducted by the pathologist is stored in the medical information system  5530 . 
     The derivation device  5540  may perform analysis of a pathological image. In this analysis, a learning model created by machine learning can be used. The derivation device  5540  may derive the classification result of a certain region, the identification result of tissues, and the like, as the analysis result. The derivation device  5540  may further derive the identification result such as cell information, count, position, and brightness information, scoring information therefor, and the like. These pieces of information derived by the derivation device  5540  may be displayed as diagnostic assistance information on the display device  5514  of the pathology system  5510 . 
     The derivation device  5540  may be a server system including one or more servers (including a cloud server). The derivation device  5540  may be a configuration incorporated into, for example, the display control device  5513  or the server  5512  in the pathology system  5510 . That is, a variety of analysis for a pathological image may be performed in the pathology system  5510 . 
     The technique according to the present disclosure may be preferably applied, for example, to the microscope  5511  among the configurations described above. Specifically, the technique according to the present disclosure can be applied to the low-resolution imager and/or the high-resolution imager in the microscope  5511 . The application of the technique according to the present disclosure to the low-resolution imager and/or the high-resolution imager leads to miniaturization of the low-resolution imager and/or the high-resolution imager, and thus miniaturization of the microscope  5511 . The miniaturization facilitates transportation of the microscope  5511  and thereby facilitates system introduction and system replacement. In addition, when the technique according to the present disclosure is applied to the low-resolution imager and/or the high-resolution imager, a part or the whole of the process from acquisition of a pathological image to analysis of the pathological image can be performed on the fly in the microscope  5511 , so that diagnostic assistance information can be output more promptly and appropriately. 
     The configuration described above is not limited to a diagnostic assistance system and may be applied generally to biological microscopes such as a confocal microscope, a fluorescent microscope, and a video microscope. Here, the observation target may be a biological sample such as cultured cell, fertilized egg, and sperm, a biological material such as cell sheet and three-dimensional cell tissue, and a living body such as zebrafish and mouse. The observation target may be observed in a microplate or a petri dish, rather than on a glass slide. 
     A moving image may be generated from still images of the observation target acquired using the microscope. For example, a moving image may be generated from still images captured successively for a predetermined period of time, or an image sequence may be generated from still images captured at predetermined intervals. With a moving image generated from still images, dynamic features of an observation target, such as motion such as pulsation, expansion, and migration of cancer cell, nerve cell, cardiac muscle tissue, sperm, and the like, and a division process of cultured cell and fertilized egg, can be analyzed using machine learning. 
     Although embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the foregoing embodiments as they are and may be susceptible to various modifications without departing from the spirit of the present disclosure. The constituent elements in different embodiments and modifications may be combined as appropriate. 
     The effects in the embodiments described in the present description are only by way of illustration and are not intended to be limitative, and any other effects may be achieved. 
     The foregoing embodiments may be used singly or may be used in combination with other embodiments. 
     The present technique may employ the configuration as follows. 
     (1) 
     A stacked light-receiving sensor comprising: 
     a first substrate; 
     a second substrate bonded to the first substrate; and connection wiring attached to the second substrate, 
     the first substrate including a pixel array in which a plurality of unit pixels are arranged in a two-dimensional matrix, 
     the second substrate including
         a converter configured to convert an analog pixel signal output from the pixel array to digital image data and   a processing unit configured to perform a process for data based on the image data, wherein       

     at least a part of the converter is disposed on a first side in the second substrate, 
     the processing unit is disposed on a second side opposite to the first side in the second substrate, and 
     the connection wiring is attached to a side other than the second side in the second substrate. 
     (2) 
     The stacked light-receiving sensor according to (1), wherein the connection wiring is a flexible cable. 
     (3) 
     The stacked light-receiving sensor according to (1) or (2), wherein the processing unit performs the process based on a neural network calculation model for data based on the image data. 
     (4) 
     An in-vehicle imaging device comprising a solid-state imaging device, a circuit board provided with an information processing device, and connection wiring connecting the solid-state imaging device and the circuit board, 
     the solid-state imaging device including
         a first substrate and   a second substrate bonded to the first substrate, the first substrate including a pixel array in which a plurality of unit pixels are arranged in a two-dimensional matrix,       

     the second substrate including
         a converter configured to convert an analog pixel signal output from the pixel array to digital image data and   a processing unit configured to perform a process for data based on the image data, wherein       

     at least a part of the converter is disposed on a first side in the second substrate, 
     the processing unit is disposed on a second side opposite to the first side in the second substrate, 
     the connection wiring is attached to a side other than the second side in the second substrate and attached to a third side of the circuit board, 
     the solid-state imaging device is installed inside a vehicle such that a light-receiving surface of the pixel array faces a front direction of the vehicle and the first side is positioned on a lower side in a vertical direction, and 
     the circuit board is installed such that at least an end on a front side of the vehicle in the circuit board protrudes to the front direction of the vehicle relative to an end on the front side of the vehicle of the solid-state imaging device and a main plane is parallel or substantially parallel to a horizontal plane. 
     (5) 
     The in-vehicle imaging device according to (4), wherein 
     one end of the connection wiring is attached to the side on the lower side in the vertical direction in the second substrate of the solid-state imaging device, and 
     another end of the connection wiring is attached to an end on a rear side of the vehicle in the circuit board. 
     (6) 
     The in-vehicle imaging device according to (4) or (5), wherein the information processing device is positioned on the front side of the vehicle relative to the solid-state imaging device. 
     (7) 
     An in-vehicle imaging device comprising a solid-state imaging device, a circuit board provided with an information processing device, and connection wiring connecting the solid-state imaging device and the circuit board, 
     the solid-state imaging device including
         a first substrate and   a second substrate bonded to the first substrate,       

     the first substrate including a pixel array in which a plurality of unit pixels are arranged in a two-dimensional matrix, 
     the second substrate including
         a converter configured to convert an analog pixel signal output from the pixel array to digital image data, and   a processing unit configured to perform a process for data based on the image data, wherein       

     at least a part of the converter is disposed on a first side in the second substrate, 
     the processing unit is disposed on a second side opposite to the first side in the second substrate, 
     the connection wiring is attached to a side other than the second side in the second substrate and attached to a third side of the circuit board, and 
     the solid-state imaging device is installed inside a vehicle such that a light-receiving surface of the pixel array faces a rear direction of the vehicle. 
     (8) 
     The in-vehicle imaging device according to (7), wherein the circuit board is installed inside the vehicle to be positioned on a surface side opposite to the light-receiving surface in the solid-state imaging device. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  imaging device 
               10  image sensor 
               11  imager 
               12  controller 
               13  signal processor 
               14 ,  14 A,  14 B,  14 C,  14 D DSP (machine learning unit) 
               14   a  interconnect 
               15 ,  15 A,  15 B,  15 C,  15 D,  15 E,  15 F memory 
               16  selector 
               17 ,  17 A ADC 
               17 B DAC 
               20  application processor 
               30  cloud server 
               40  network 
               100 ,  200 ,  300  first substrate 
               101  pixel array 
               101   a  unit pixel 
               102  TSV array 
               103  pad array 
               104  optical system 
               120 ,  320  second substrate 
               400  circuit board 
               402  flexible cable 
               410  vehicle 
               411  windshield 
               412  rear window 
             L 101  to L 104  side 
             O 100  center of first substrate 
             O 101  center of pixel array