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JP-2026075449-A - Light detection device and electronic equipment

JP2026075449AJP 2026075449 AJP2026075449 AJP 2026075449AJP-2026075449-A

Abstract

[Problem] To enable high-speed and high-precision event detection regardless of illuminance, without degrading noise characteristics. [Solution] The light detection device comprises a pixel having a photoelectric conversion element that accumulates charge according to the amount of incident light, and a floating diffusion region that holds the charge transferred from the photoelectric conversion element; a logarithmic response circuit that logarithmically converts a current corresponding to the charge overflowing from the photoelectric conversion element into a voltage; a first event detection circuit that detects an event based on the amount of change in the illuminance of the incident light based on the voltage corresponding to the charge held in the floating diffusion region after the exposure period has ended; and a second event detection circuit that detects an event based on the amount of change in the illuminance of the incident light based on the output voltage of the logarithmic response circuit. [Selection Diagram] Figure 3

Inventors

  • 高橋 裕嗣

Assignees

  • ソニーセミコンダクタソリューションズ株式会社

Dates

Publication Date
20260508
Application Date
20241022

Claims (20)

  1. A photoelectric conversion element that accumulates charge according to the amount of incident light, A pixel having a floating diffusion region that holds the charge transferred from the photoelectric conversion element, A logarithmic response circuit that logarithmically converts the current corresponding to the charge overflowing from the photoelectric conversion element into a voltage, A first event detection circuit detects an event based on the change in the illuminance of incident light, based on a voltage corresponding to the charge held in the floating diffusion region after the exposure period has ended. A second event detection circuit detects an event based on the change in the illuminance of incident light, based on the output voltage of the logarithmic response circuit. Equipped with, Light detection device.
  2. The pixel has an amplifier transistor to which the voltage converted in the floating diffusion region is applied at the gate. The first event detection circuit detects the event based on a change in the drain or source voltage of the amplifier transistor. The light detection device according to claim 1.
  3. The first event detection circuit includes a first subtractor that detects the amount of change in voltage corresponding to the charge held in the floating diffusion region, The system includes a first comparator that determines whether the amount of change detected by the first subtractor exceeds a first threshold, The second event detection circuit includes a second subtractor that detects the change in the logarithmically transformed voltage in the logarithmic response circuit, The system includes a second comparator that determines whether the amount of change detected by the second subtractor exceeds a second threshold, The light detection device according to claim 1.
  4. The first subtractor detects the potential difference between the voltage corresponding to the charge held in the floating diffusion region in the first frame and the voltage corresponding to the charge held in the floating diffusion region in the second frame following the first frame. The first comparator determines whether the potential difference detected by the first subtractor exceeds the first threshold, The second subtractor detects the potential difference between the voltage logarithmically transformed by the logarithmic response circuit in the first frame and the voltage logarithmically transformed by the logarithmic response circuit in the second frame. The second comparator determines whether the potential difference detected by the second subtractor exceeds the second threshold. The light detection device according to claim 3.
  5. The second event detection circuit detects an event during the first period within the exposure period, The first event detection circuit detects an event during the second period after the end of the exposure period. The light detection device according to claim 3.
  6. The second event detection circuit includes a first discharge transistor that turns on after detecting the event and discharges the charge overflowing from the photoelectric conversion element to a reference voltage node. The first event detection circuit detects the event during the ON period of the first emission transistor. The light detection device according to claim 5.
  7. The system includes a transfer circuit that transfers the charge of the photoelectric conversion element to the floating diffusion region during the second period. The light detection device according to claim 5.
  8. The device comprises a pixel array section having a plurality of pixels arranged in a first direction and a second direction intersecting the first direction. The light detection device according to claim 3.
  9. Multiple pixels within the pixel array simultaneously transfer the charge of the photoelectric conversion element to the floating diffusion region, and simultaneously discharge the charge transferred to the floating diffusion region and the charge overflowing from the photoelectric conversion element. The light detection device according to claim 8.
  10. The aforementioned pixel array portion has a group of pixels including a plurality of pixels, Multiple pixels within the pixel array transfer the charge of the photoelectric conversion element to the floating diffusion region at timings for each pixel group, and discharge the charge transferred to the floating diffusion region and the charge overflowing from the photoelectric conversion element at timings for each pixel group. The light detection device according to claim 9.
  11. The plurality of pixels include a first pixel connected to the first event detection circuit and the second event detection circuit, and a second pixel connected to a pixel circuit that outputs a pixel signal having grayscale information based on the charge accumulated in the photoelectric conversion element. The light detection device according to claim 8.
  12. A first holding circuit that holds the event detected by the first event detection circuit, The system comprises a second holding circuit that holds an event detected by the second event detection circuit, The light detection device according to claim 8.
  13. The first holding circuit sequentially outputs first event detection signals based on events detected by a plurality of first event detection circuits. The second holding circuit sequentially outputs a second event detection signal based on the events detected by the multiple second event detection circuits. The light detection device according to claim 12.
  14. An output circuit that outputs a request signal requesting the transmission of a second event detection signal when multiple second event detection circuits detect an event, The system comprises an arbiter that mediates multiple request signals, The first holding circuit sequentially outputs first event detection signals based on events detected by a plurality of first event detection circuits. The second holding circuit outputs the second event detection signal based on the arbitration result of the arbiter. The light detection device according to claim 12.
  15. The arbiter mediates the request signal during the exposure period. The light detection device according to claim 14.
  16. The system includes an illuminance detection circuit that detects the illuminance of the incident light based on the time difference from the start of the exposure period until the first output of the second event detection signal. The light detection device according to claim 14.
  17. The first comparator includes at least one of a third comparator that detects when the amount of voltage drop corresponding to the charge held in the floating diffusion region exceeds a third threshold after the exposure period ends, and a fourth comparator that detects when the amount of voltage rise corresponding to the charge held in the floating diffusion region exceeds a fourth threshold after the exposure period ends. The second comparator comprises at least one of a fifth comparator that detects when the amount of voltage drop converted by the logarithmic response circuit during the exposure period exceeds a fifth threshold, and a sixth comparator that detects when the amount of voltage rise converted by the logarithmic response circuit during the exposure period exceeds a sixth threshold. The first holding circuit comprises at least one of a third holding circuit that holds an event based on the detection result of the third comparator, and a fourth holding circuit that holds an event based on the detection result of the fourth comparator. The second holding circuit comprises at least one of a fifth holding circuit that holds an event based on the detection result of the fifth comparator, and a sixth holding circuit that holds an event based on the detection result of the sixth comparator. The light detection device according to claim 12.
  18. The first event detection circuit turns on after detecting the event to discharge the charge transferred to the floating diffusion region to a reference voltage node, and after discharging the charge, a second discharge transistor transfers the charge overflowing from the photoelectric conversion element to the logarithmic response circuit. The light detection device according to claim 1.
  19. The second event detection circuit detects the change in the illuminance of the incident light at the illuminance at which the photoelectric conversion element saturates, The first event detection circuit detects changes in the illuminance of the incident light at an illuminance level in which the photoelectric conversion element does not saturate. The light detection device according to claim 1.
  20. A light detection device according to claim 1 that outputs image data, The system comprises a signal processing unit that performs signal processing on the aforementioned image data, electronic equipment.

Description

This disclosure relates to a photodetector and electronic equipment. An Event-Based Vision Sensor (EVS) has been proposed to rapidly acquire event information from photoelectric conversion elements where events such as brightness changes occur within the imaging scene. Compared to frame-type vision sensors, specifically CMOS (Complementary Metal Oxide Semiconductor) image sensors (hereinafter referred to as CIS), which scan all pixels at predetermined intervals to acquire gradation information for each pixel, the EVS features low power consumption and high-speed event detection. For example, a solid-state image sensor has been proposed that enables simultaneous detection of address events and image capture by providing a connecting transistor that connects the address event detection circuit and the pixel circuit (see Patent Document 1). Japanese Patent Publication No. 2020-88724 A block diagram showing the configuration of an electronic device according to the first embodiment of this disclosure.A block diagram showing the configuration of a photodetector according to the first embodiment of this disclosure.A circuit diagram showing the configuration of a pixel and a pixel circuit according to the first embodiment of this disclosure.A waveform diagram showing the relationship between the output voltage of a pixel and the illuminance of the incident light.A timing chart showing the operation of the pixel array portion according to the first embodiment of this disclosure.Timing chart showing the operation of pixels and pixel circuits when high-intensity events are detected.A timing chart showing the operation of pixels and pixel circuits when low-light events are detected.Cross-sectional view of a pixel and its surrounding area.A diagram showing the stacked structure of a light detection device.A block diagram showing the configuration of a photodetector according to one modified example.A circuit diagram showing the configuration of pixels and pixel circuits in a comparative example.A block diagram showing the configuration of a photodetector according to a second embodiment of the present disclosure.A circuit diagram showing the configuration of a pixel and a pixel circuit according to a second embodiment of the present disclosure.A timing chart showing the operation of the pixel array portion according to the second embodiment of this disclosure.A truth table illustrating the operation of the second holding circuit and output circuit according to the second embodiment of the present disclosure.A block diagram showing the configuration of a photodetector according to a third embodiment of this disclosure.A timing chart showing the operation of the pixel array portion according to the third embodiment of this disclosure.A block diagram showing an example of a general configuration of a vehicle control system.An explanatory diagram showing an example of the installation location of the external information detection unit and the imaging unit. The embodiments of the photodetector and electronic equipment will be described below with reference to the drawings. While the main components of the photodetector and electronic equipment will be described below, there may be components and functions not shown or described. The following description does not exclude any components or functions not shown or described. (First embodiment) Figure 1 is a block diagram showing the configuration of an electronic device 1 equipped with a light detection device 10 according to a first embodiment of the present disclosure. This electronic device 1 is a device that detects events based on changes in the illuminance of incident light, and comprises a light detection device (light detection element) 10, an imaging lens 2, a recording unit 3, and a control unit 4. Examples of the electronic device 1 include a sensing device, a camera mounted on an industrial robot, or an in-vehicle camera, but the specific application and configuration of the electronic device 1 are arbitrary. The light detection device 10 performs event detection by converting incident light into photoelectric energy. The light detection device 10 may, for example, have an EVS (Earth View Sensor) function. The light detection device 10 may also have a CIS (Constant Identification System) function for generating grayscale image data. Furthermore, the light detection device 10 may generate event detection image data based on the detection location, detection time, and type of detected event. Additionally, the light detection device 10 may generate image data by combining the grayscale image data and the event detection image data. The imaging lens 2 focuses incident light and guides it to the photodetector 10. The recording unit 3 records image data input from the photodetector 10 via the transmission line 5. The recording unit 3 may be located on a server connected via a network. The control unit 4 controls the imaging timing of the photodetector 10 via the control