Solid-state imaging element, imaging device, and control method of solid-state imaging element

Patent metadata

Field	Value
Publication number	US-2020358977-A1
Application number	US-201916962783-A
Country	US
Kind code	A1
Filing date	Jan 18, 2019
Priority date	Jan 23, 2018
Publication date	Nov 12, 2020
Grant date	—

Abstract

An object is to reduce a circuit scale in a solid-state imaging element that detects an address event.
The solid-state imaging element is provided with a plurality of photoelectric conversion elements, a signal supply unit, and a detection unit. In this solid-state imaging element, each of the plurality of photoelectric conversion elements photoelectrically converts incident light to generate a first electric signal. Furthermore, in the solid-state imaging element, the detection unit detects whether or not a change amount of the first electric signal of each of the plurality of photoelectric conversion elements exceeds a predetermined threshold and outputs a detection signal indicating a result of the detection result.

First claim

1 . A solid-state imaging element comprising:
a plurality of photoelectric conversion elements each of which photoelectrically converts incident light to generate a first electric signal; and a detection unit that detects whether or not a change amount of the first electric signal of each of the plurality of photoelectric conversion elements exceeds a predetermined threshold and outputs a detection signal indicating a result of the detection.

2 . The solid-state imaging element according to claim 1 , further comprising:
a signal supply unit that supplies the first electric signal of each of the plurality of photoelectric conversion elements to a connection node according to a predetermined control signal, wherein the detection unit detects whether or not the change amount of the first electric signal supplied to the connection node exceeds the predetermined threshold.

3 . The solid-state imaging element according to claim 2 , further comprising:
a pixel signal generation unit that generates a pixel signal according to a second electric signal generated by the photoelectric conversion element, wherein the signal supply unit sequentially selects the second electric signal of each of the plurality of photoelectric conversion elements to supply to the pixel signal generation unit in a case where the change amount exceeds the predetermined threshold.

4 . The solid-state imaging element according to claim 3 ,
wherein the connection node is connected to N (N is an integer not smaller than 2) of the photoelectric conversion elements, and the pixel signal generation unit generates a signal of a voltage corresponding to the second electric signal of an element selected according to a selection signal out of M (M is an integer smaller than N) of the photoelectric conversion elements as the pixel signal.

5 . The solid-state imaging element according to claim 3 ,
wherein the pixel signal generation unit is provided with: a reset transistor that initializes a floating diffusion layer; an amplification transistor that amplifies a signal of a voltage of the floating diffusion layer; and a selection transistor that outputs the amplified signal as the pixel signal according to a selection signal, and the detection unit is provided with: a plurality of N-type transistors that converts the first electric signal into a voltage signal of a logarithm of the first electric signal; and a P-type transistor that supplies a constant current to the plurality of N-type transistors.

6 . The solid-state imaging element according to claim 5 ,
wherein the plurality of photoelectric conversion elements is arranged on a light reception chip, and the detection unit and the pixel signal generation unit are arranged on a detection chip stacked on the light reception chip.

7 . The solid-state imaging element according to claim 5 ,
wherein the plurality of photoelectric conversion elements and the reset transistor are arranged on a light reception chip, and the detection unit, the amplification transistor, and the selection transistor are arranged on a detection chip stacked on the light reception chip.

8 . The solid-state imaging element according to claim 5 ,
wherein the plurality of photoelectric conversion elements, the reset transistor, and the plurality of N-type transistors are arranged on a light reception chip, and the amplification transistor, the selection transistor, and the P-type transistor are arranged on a detection chip stacked on the light reception chip.

9 . The solid-state imaging element according to claim 5 ,
wherein the plurality of photoelectric conversion elements, the pixel signal generation unit, and the plurality of N-type transistors are arranged on a light reception chip, and the P-type transistor is arranged on a detection chip stacked on the light reception chip.

10 . The solid-state imaging element according to claim 1 , further comprising:
a signal supply unit that supplies the first electric signal of each of the plurality of photoelectric conversion elements to a connection node according to a predetermined control signal, wherein the detection unit further outputs a pixel signal corresponding to the first electric signal, the signal supply unit sequentially selects the first electric signal of each of the plurality of photoelectric conversion elements to supply to the connection node in a case where the change amount exceeds the predetermined threshold, and the detection unit is provided with: first and second N-type transistors that convert the first electric signal into a voltage signal of a logarithm of the first electric signal; and a P-type transistor that supplies a constant current to the first and second N-type transistors.

11 . The solid-state imaging element according to claim 10 , further comprising:
an analog/digital converter that converts the pixel signal into a digital signal, wherein the plurality of photoelectric conversion elements, the signal supply unit, and the first and second N-type transistors are arranged on a light reception chip, and the P-type transistor and at least a part of the analog/digital converter are arranged on a detection chip stacked on the light reception chip.

12 . The solid-state imaging element according to claim 11 ,
wherein the analog/digital converter is provided with: a signal side transistor to which the pixel signal is input; a reference side transistor to which a predetermined reference signal is input; a constant current source connected to the signal side transistor and the reference side transistor; and a current mirror circuit that amplifies a difference between the pixel signal and the predetermined reference signal to output, the plurality of photoelectric conversion elements, the signal supply unit, the first and second N-type transistors, the signal side transistor, the reference side transistor, and the constant current source are arranged on a light reception chip, and the P-type transistor and the current mirror circuit are arranged on a detection chip stacked on the light reception chip.

13 . The solid-state imaging element according to claim 1 , further comprising:
a connection node connected to the photoelectric conversion element and the detection unit; and for each of the plurality of photoelectric conversion elements, a current/voltage conversion unit that converts a photocurrent into a voltage signal of a logarithm of the photocurrent, a buffer that corrects the voltage signal to output, a capacitor inserted between the buffer and the connection node, and a signal processing unit that supplies an electric signal of each of the plurality of photoelectric conversion elements to the connection node through the current/voltage conversion unit, the buffer, and the capacitor according to a predetermined control signal, wherein the electric signal includes the photocurrent and the voltage signal.

14 . The solid-state imaging element according to claim 13 , further comprising:
an analog/digital converter that converts a pixel signal into a digital signal, wherein each of a predetermined number of current/voltage conversion units arranged in a predetermined direction further generates a signal of a voltage corresponding to the photocurrent as the pixel signal, and outputs the pixel signal to the analog/digital converter.

15 . The solid-state imaging element according to claim 13 , further comprising:
an analog/digital converter that converts a pixel signal into a digital signal for each of the plurality of photoelectric conversion elements, wherein each of current/voltage co

Assignees

• Sony Semiconductor Solutions Corp

Inventors

• Niwa Atsumi
• Oike Yusuke

Classifications

• H04N25/707

  Pixels for event detection · CPC title

• H04N25/47 Primary

  Image sensors with pixel address output; Event-driven image sensors; Selection of pixels to be read out based on image data · CPC title

• H04N25/443

  by reading pixels from selected two-dimensional [2D] regions of the array, e.g. for windowing or digital zooming · CPC title

• H04N25/445 Primary

  by skipping some contiguous pixels within the read portion of the array · CPC title

• H04N25/78

  Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters · CPC title