Imaging element, gain control method, program, and electronic device

Patent metadata

Field	Value
Publication number	US-9876978-B2
Application number	US-201515302258-A
Country	US
Kind code	B2
Filing date	Apr 3, 2015
Priority date	Apr 16, 2014
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

The present disclosure relates to an imaging element, a gain control method, a program, and an electronic device that can capture an image with a high image quality or a high dynamic range with lower power consumption. The imaging element includes: an A/D conversion unit configured to A/D-convert a pixel signal outputted from a pixel; and a reference signal generation unit. The reference signal generation unit includes a prescribed number of pairs of transistors forming a current mirror circuit, and a switching unit configured to switch the number of transistors connected to the current mirror circuit. The switching unit is controlled so as to reduce the number of transistors connected to the current mirror circuit when the pixel signal is A/D-converted to a high gain. The present technology can be applied to a CMOS image sensor, for example.

First claim

What is claimed is:

1. An imaging element comprising:
an A/D conversion unit configured to analog-to-digital (A/D)-convert a pixel signal outputted from a pixel;
a reference signal generation unit configured to generate a reference signal that is referred to when the pixel signal is A/D-converted in the A/D conversion unit,
wherein the reference signal generation unit includes:
a prescribed number of pairs of transistors forming a current mirror circuit, and
a switching unit configured to switch the number of transistors connected to the current mirror circuit; and

a control unit configured to acquire a brightness of a captured image and control the switching unit so as to reduce the number of transistors connected to the current mirror circuit at a time of, on the basis of the brightness of the image, setting a gain at a time when the pixel signal is A/D-converted by the A/D conversion unit to a high gain.

2. The imaging element according to claim 1 , wherein the control unit controls the switching unit so as to reduce the number of transistors connected to the current mirror circuit and furthermore reduces a reference current of the current mirror circuit.

3. A gain control method for an imaging element,
the imaging element including
an A/D conversion unit configured to analog-to-digital (A/D)-convert a pixel signal outputted from a pixel, and
a reference signal generation unit configured to generate a reference signal that is referred to when the pixel signal is A/D-converted in the A/D conversion unit,
the reference signal generation unit including
a prescribed number of pairs of transistors forming a current mirror circuit, and
a switching unit configured to switch the number of transistors connected to the current mirror circuit,
the gain control method comprising:
a step of acquiring a brightness of a captured image; and
a step of controlling the switching unit so as to reduce the number of transistors connected to the current mirror circuit at a time of, on the basis of the brightness of the image, setting a gain at a time when the pixel signal is A/D-converted by the A/D conversion unit to a high gain.

4. A non-transitory medium for storing a program, the program for causing a computer to execute control of an imaging element,
the imaging element including:
an A/D conversion unit configured to analog-to-digital (A/D)-convert a pixel signal outputted from a pixel; and
a reference signal generation unit configured to generate a reference signal that is referred to when the pixel signal is A/D-converted in the A/D conversion unit, the reference signal generation unit including:
a prescribed number of pairs of transistors forming a current mirror circuit; and
a switching unit configured to switch the number of transistors connected to the current mirror circuit,

the program being configured to cause a computer to execute processing including:
a step of acquiring a brightness of a captured image; and
a step of controlling the switching unit so as to reduce the number of transistors connected to the current mirror circuit at a time of, on the basis of the brightness of the image, setting a gain at a time when the pixel signal is A/D-converted by the A/D conversion unit to a high gain.

5. An electronic device comprising an imaging element, the imaging element including:
an A/D conversion unit configured to analog-to-digital (A/D)-convert a pixel signal outputted from a pixel;
a reference signal generation unit configured to generate a reference signal that is referred to when the pixel signal is A/D-converted in the A/D conversion unit,
the reference signal generation unit including:
a prescribed number of pairs of transistors forming a current mirror circuit and
a switching unit configured to switch the number of transistors connected to the current mirror circuit; and

a control unit configured to acquire a brightness of a captured image and control the switching unit so as to reduce the number of transistors connected to the current mirror circuit at a time of, on the basis of the brightness of the image, setting a gain at a time when the pixel signal is A/D-converted by the A/D conversion unit to a high gain.

Assignees

• Sony Corp

Inventors

• Okada Chihiro

Classifications

• H04N23/76 Primary

  by influencing the image signals · CPC title

• H04N23/741

  by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors · CPC title

• H04N23/71

  Circuitry for evaluating the brightness variation · CPC title

• H04N5/378 Primary

  Electricity · mapped topic

• H04N5/2351

  Electricity · mapped topic