Search

EP-4738872-A1 - PHOTOELECTRIC CONVERSION DEVICE AND PHOTOELECTRIC CONVERSION SYSTEM HAVING PHOTOELECTRIC CONVERSION DEVICE

EP4738872A1EP 4738872 A1EP4738872 A1EP 4738872A1EP-4738872-A1

Abstract

The present invention has an exposure control unit that generates a signal defining a plurality of second exposure periods which are included in a first exposure period corresponding to one frame and which are each shorter than the first exposure period. The present invention has a timing generation unit that generates a pulse signal defining time information within each of the second exposure periods. The present invention has a measurement unit that measures a number of the pulse signal from an initial detection of a photon in each of the second exposure periods, based on the pulse signal generated by the timing generation unit.

Inventors

  • SEKINE, HIROSHI
  • MORIMOTO, KAZUHIRO
  • ISODA, NAOKI

Assignees

  • Canon Kabushiki Kaisha

Dates

Publication Date
20260506
Application Date
20240628

Claims (20)

  1. A photoelectric conversion device comprising: a photoelectric conversion element that receives photons; an exposure control unit that generates a signal defining a plurality of second exposure periods which are included in a first exposure period corresponding to one frame and which are each shorter than the first exposure period; a timing generation unit that generates a pulse signal defining time information within each of the second exposure periods; and a measurement unit that measures a number of the pulse signal from an initial detection of a photon in each of the second exposure periods, based on the pulse signal generated by the timing generation unit.
  2. The photoelectric conversion device according to claim 1, wherein the timing generation unit generates an equally spaced pulse signal, and the pulse signal is configured to be inputted into the measurement unit in at least each of the second exposure periods.
  3. The photoelectric conversion device according to claim 1, wherein the timing generation unit generates an unequally spaced pulse signal, and the pulse signal is configured to be inputted into the measurement unit in at least each of the second exposure periods.
  4. The photoelectric conversion device according to claim 3, wherein the unequally spaced pulse signal is configured such that a period thereof increases according to elapsed time in each of the second exposure periods.
  5. The photoelectric conversion device according to claim 4, characterized in that a spacing of the unequally spaced pulse signal is set to be a logarithmic compression of real space.
  6. The photoelectric conversion device according to claim 1, characterized in that the measurement unit includes a waveform shaping circuit that converts a signal from the photoelectric conversion element into a pulse signal.
  7. The photoelectric conversion device according to claim 6, characterized in that the measurement unit includes a timing determination circuit, and the timing determination circuit outputs a pulse signal generated by the timing generation unit from a timing at which a photon is initially detected within each of the second exposure periods.
  8. The photoelectric conversion device according to claim 7, wherein the measurement unit includes a counter circuit, and the counter circuit obtains a count value by counting each input of a pulse signal outputted from the timing determination circuit within each of the second exposure periods.
  9. The photoelectric conversion device according to claim 8, characterized in that the counter circuit outputs the sum of the count values for the plurality of second exposure periods.
  10. The photoelectric conversion device according to claim 1, characterized in that the photoelectric conversion element is an avalanche photodiode.
  11. The photoelectric conversion device according to claim 10, wherein a switch for performing a charge operation is disposed between the avalanche photodiode and a power supply that applies a reverse bias to the avalanche photodiode.
  12. The photoelectric conversion device according to claim 11, wherein each of the second exposure periods is a period from a timing at which the charge operation is performed to a timing at which the next charge operation is performed.
  13. The photoelectric conversion device according to claim 11, wherein a pulse signal inputted into the switch for performing the charge operation and the pulse signal generated by the timing generation unit are generated from a base clock signal.
  14. The photoelectric conversion device according to claim 1, wherein the measurement unit has a select circuit, the plurality of second exposure periods include one second exposure period and another second exposure period, and the select circuit selects whether or not to output a signal corresponding to the pulse signal defining time information within the other second exposure period depending on whether a photon is not detected or is detected in the one second exposure period.
  15. The photoelectric conversion device according to claim 14, characterized in that if a photon is not detected in the one second exposure period, the select circuit outputs a prescribed value, irrespectively of the time from the beginning of the other second exposure period until a photon is initially detected.
  16. The photoelectric conversion device according to claim 1, wherein a first board and a second board are stacked, the first board has the photoelectric conversion element, and the second board has the exposure control unit, the timing generation unit, and the measurement unit.
  17. The photoelectric conversion device according to claim 8, wherein a first board, a second board, and a third board are stacked, the first board has the photoelectric conversion element, and the second board has the waveform shaping circuit, the timing determination circuit, and the counter circuit, and the third board has the timing determination circuit and the counter circuit.
  18. The photoelectric conversion device according to claim 17, wherein a pulse signal generated by the timing generation unit to be inputted into the timing determination circuit provided on the second board and a pulse signal generated by the timing generation unit to be inputted into the timing determination circuit provided on the third board are different.
  19. A photoelectric conversion system comprising: the photoelectric conversion device according to any one of claims 1 to 18; and a signal processing unit that generates an image using a signal outputted by the photoelectric conversion device.
  20. A moving body including the photoelectric conversion device according to any one of claims 1 to 18, wherein the moving body has a control unit that controls movement of the moving body using a signal outputted by the photoelectric conversion device.

Description

Technical Field The present invention relates to a photoelectric conversion device and a photoelectric conversion system including a photoelectric conversion device. Background Art PTL 1 discloses a configuration for measuring the time until a counter saturates for each pixel and estimating light intensity by extrapolation from the time and the count value. This configuration allows for expansion of the dynamic range. Citation List Patent Literature PTL 1: International Publication No. WO 2020/179928 Summary of Invention Technical Problem According to the configuration in PTL 1, the counter stops once saturated, which results in missing signal information after the counter stops. This could result in, for example, artifacts when shooting a moving subject, or brightness variations when shooting a flickering light source. Solution to Problem The present invention provides a photoelectric conversion device including a photoelectric conversion element that receives photons, an exposure control unit that generates a signal defining a plurality of second exposure periods which are included in a first exposure period corresponding to one frame and which are each shorter than the first exposure period, a timing generation unit that generates a pulse signal defining time information within each of the second exposure periods, and a measurement unit that measures a number of the pulse signal from an initial detection of a photon in each of the second exposure periods, based on the pulse signal generated by the timing generation unit. Advantageous Effects of Invention According to the present invention, it is possible to acquire more signal information compared to PTL 1. Brief Description of Drawings [Fig. 1] Fig. 1 is a diagram illustrating an example of the configuration of a pixel circuit.[Fig. 2A] Fig. 2A is a diagram for explaining the relationship between a detection time and a number of incident photons.[Fig. 2B] Fig. 2B is a diagram for explaining the relationship between a detection time and a number of incident photons.[Fig. 3A] Fig. 3A is a diagram for explaining the relationship between a detection time and a number of incident photons.[Fig. 3B] Fig. 3B is a diagram for explaining the relationship between a detection time and a number of incident photons.[Fig. 3C] Fig. 3C is a diagram for explaining the relationship between a detection time and a number of incident photons.[Fig. 4] Fig. 4 is a diagram for explaining photon detection probability.[Fig. 5A] Fig. 5A is a diagram for explaining an expected value of a number of incident photons.[Fig. 5B] Fig. 5B is a diagram for explaining input/output characteristics.[Fig. 5C] Fig. 5C is a diagram for explaining input/output characteristics.[Fig. 6] Fig. 6 is a diagram for explaining a photoelectric conversion device according to a first embodiment.[Fig. 7] Fig. 7 is a diagram for explaining a photoelectric conversion device according to the first embodiment.[Fig. 8] Fig. 8 is a diagram for explaining a photoelectric conversion device according to the first embodiment.[Fig. 9] Fig. 9 is a diagram for explaining a photoelectric conversion device according to the first embodiment.[Fig. 10A] Fig. 10A is a diagram for explaining a pixel circuit of, and the driving of, a photoelectric conversion device according to the first embodiment.[Fig. 10B] Fig. 10B is a diagram for explaining a pixel circuit of, and the driving of, a photoelectric conversion device according to the first embodiment.[Fig. 10C] Fig. 10C is a diagram for explaining a pixel circuit of, and the driving of, a photoelectric conversion device according to the first embodiment.[Fig. 11] Fig. 11 is a diagram for explaining an operating sequence of a photoelectric conversion device according to the first embodiment.[Fig. 12] Fig. 12 is a diagram for explaining cases where a clock signal defining time information is equally spaced and unequally spaced.[Fig. 13A] Fig. 13A is a diagram for explaining a clock signal defining time information, and input/output characteristics.[Fig. 13B] Fig. 13B is a diagram for explaining a clock signal defining time information, and input/output characteristics.[Fig. 14A] Fig. 14A is a diagram for explaining a pixel circuit of a photoelectric conversion device according to a second embodiment.[Fig. 14B] Fig. 14B is a diagram for explaining a pixel circuit of a photoelectric conversion device according to the second embodiment.[Fig. 15] Fig. 15 is a diagram for explaining an operating sequence of a photoelectric conversion device according to the second embodiment.[Fig. 16] Fig. 16 is a diagram for explaining a pixel circuit of a photoelectric conversion device according to a third embodiment.[Fig. 17] Fig. 17 is a diagram for explaining an operating sequence of a photoelectric conversion device according to the third embodiment.[Fig. 18] Fig. 18 is a diagram for explaining an effect of a photoelectric conversion device according to the third embodiment.[Fig. 19] Fig. 19 is