Optical sensor

Patent metadata

Field	Value
Publication number	US-11480464-B2
Application number	US-202017082265-A
Country	US
Kind code	B2
Filing date	Oct 28, 2020
Priority date	Oct 28, 2019
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

Provided is an optical sensor including: a first photodetector including a first photodiode and having a first wavelength sensitivity characteristic; a first resistor having one end connected to a cathode of the first photodiode, and another end connected to a ground point; a second photodetector including a second photodiode and having a second wavelength sensitivity characteristic; a second resistor having one end connected to a cathode of the second photodiode, and another end connected to the ground point; and an amplifier circuit having a first input terminal connected to the first photodiode, a second input terminal connected to the second photodiode, and an output terminal configured to output a potential based on a potential of the first input terminal and a potential of the second input terminal, and using, as an operating power supply, electric power generated by electromotive force of the first photodetector and the second photodetector.

First claim

What is claimed is:

1. An optical sensor, comprising:
a first photodetector which includes a photodiode and has a first wavelength sensitivity characteristic;
a first resistor having a first end connected to a cathode of the photodiode of the first photodetector, and a second end connected to a ground point;
a second photodetector which includes a photodiode having an anode connected to an anode of the photodiode of the first photodetector, and has a second wavelength sensitivity characteristic being different from the first wavelength sensitivity characteristic;
a second resistor having a first end connected to a cathode of the photodiode of the second photodetector, and a second end connected to the ground point; and
an amplifier circuit having a power supply terminal, a first input terminal connected to the cathode of the photodiode of the first photodetector, a second input terminal connected to the cathode of the photodiode of the second photodetector, and an output terminal configured to output a potential based on a difference between a potential of the first input terminal and a potential of the second input terminal, the amplifier circuit being configured to use, as an operating power supply, electric power generated by electromotive force of the photodiode of the first photodetector and the photodiode of the second photodetector.

2. The optical sensor according to claim 1 , further comprising a booster circuit configured to supply electric power obtained by boosting the electric power generated by the electromotive force to the power supply terminal of the amplifier circuit.

3. The optical sensor according to claim 1 ,
wherein the first photodetector includes a plurality of cascaded photodiodes, and
wherein the second photodetector includes a plurality of cascaded photodiodes.

4. The optical sensor according to claim 1 , further comprising:
an n-channel transistor; and
a photodetection current output terminal,
wherein the n-channel transistor has a gate connected to the output terminal of the amplifier circuit, a source connected to the first input terminal of the amplifier circuit, and a drain connected to the photodetection current output terminal.

5. The optical sensor according to claim 1 , further comprising:
a first input-stage transistor; and
a second input-stage transistor,
wherein the first input-stage transistor is a depletion type n-channel transistor, and has a gate connected to the first input terminal of the amplifier circuit,
wherein the second input-stage transistor is a depletion type n-channel transistor, and has a gate connected to the second input terminal of the amplifier circuit.

6. The optical sensor according to claim 1 , further comprising:
a first input-stage transistor; and
a second input-stage transistor,
wherein the first input-stage transistor has a source connected to the first input terminal of the amplifier circuit via a resistor,
wherein the second input-stage transistor has a source connected to the second input terminal of the amplifier circuit via a resistor, and
wherein each of the first input-stage transistor and the second input-stage transistor is a depletion type n-channel transistor.

Assignees

• Ablic Inc

Inventors

• Utsunomiya Fumiyasu
• Douseki Takakuni
• Tanaka Ami

Classifications

• G01J1/4228

  arrangements with two or more detectors, e.g. for sensitivity compensation · CPC title

• G01J2001/446

  Photodiode · CPC title

• G01J1/0247

  using a charging unit · CPC title

• G01J2001/448

  Array [CCD] · CPC title

• G01J1/44 Primary

  Electric circuits {(for command of an exposure part G03B7/02)} · CPC title