Photoelectric conversion element, image reading device, image forming apparatus, and photoelectric conversion method

Patent metadata

Field	Value
Publication number	US-2016112660-A1
Application number	US-201514873628-A
Country	US
Kind code	A1
Filing date	Oct 2, 2015
Priority date	Oct 16, 2014
Publication date	Apr 21, 2016
Grant date	—

Abstract

A photoelectric conversion element includes a light receiving element, a buffer unit, a current control circuit, and an elimination circuit. The light receiving element generates electrical charge according to an amount of light received. The buffer unit buffers and outputs a voltage signal according to the electrical charge generated by the light receiving element. When the buffer unit outputs the voltage signal, the current control circuit controls electric current flowing through the buffer unit so as to be a predetermined amount of electric current. The elimination circuit eliminates high-frequency components in a band equal to or higher than a predetermined band from the voltage signal output from the buffer unit.

First claim

What is claimed is:

1 . A photoelectric conversion element comprising:
a light receiving element that generates electrical charge according to an amount of light received; a buffer unit that buffers and outputs a voltage signal according to the electrical charge generated by the light receiving element; a current control circuit that controls, when the buffer unit outputs the voltage signal, electric current flowing through the buffer unit so as to be a predetermined amount of electric current; and an elimination circuit that eliminates high-frequency components in a band equal to or higher than a predetermined band from the voltage signal output from the buffer unit.

2 . The photoelectric conversion element according to claim 1 , wherein
the elimination circuit includes a MOS transistor, and the band of high-frequency components to be eliminated is determined in advance according to size of an on-resistance of the MOS transistor.

3 . The photoelectric conversion element according to claim 2 , wherein
the elimination circuit includes a node to which an arbitrary voltage can be applied so that a value of the on-resistance of the MOS transistor can be changed.

4 . The photoelectric conversion element according to claim 1 , further comprising a CDS unit that performs correlated double sampling on the voltage signal output from the buffer unit, wherein
the elimination circuit eliminates high-frequency components in a band higher than a band of frequency components that the CDS unit can eliminate from the voltage signal output from the buffer unit.

5 . The photoelectric conversion element according to claim 1 , wherein
the light receiving elements are arranged in one direction with respect to each color of light received.

6 . The photoelectric conversion element according to claim 5 , wherein
the elimination circuit eliminates high-frequency components so that fixed pattern noise generated in the light receiving element is equal to or less than a predetermined threshold.

7 . An image reading device according to claim 1 , comprising the photoelectric conversion element of claim 1 .

8 . An image forming apparatus according to claim 7 , comprising:
the image reading device of claim 7 ; and an image forming unit that forms an image on the basis of output of the image reading device.

9 . A photoelectric conversion method performed by a photoelectric conversion element, the method comprising:
generating, by a light receiving element, electrical charge according to an amount of light received; buffering and outputting, by a buffer unit, a voltage signal according to the electrical charge generated at the light receiving element; controlling, by a current control circuit, when the buffer unit outputs the voltage signal, electric current flowing through the buffer unit so as to be a predetermined amount of electric current; and eliminating, by an elimination circuit, high-frequency components in a band equal to or higher than a predetermined band from the voltage signal output from the buffer unit.

10 . A photoelectric conversion element comprising:
light receiving means for generating electrical charge according to an amount of light received; buffer means for buffering and outputting a voltage signal according to the electrical charge generated by the light receiving means; current control means for controlling, when the buffer means outputs the voltage signal, electric current flowing through the buffer means so as to be a predetermined amount of electric current; and elimination means for eliminating high-frequency components in a band equal to or higher than a predetermined band from the voltage signal output from the buffer means.

Assignees

• Nakazawa Masamoto
• Kanno Tohru

Inventors

• Nakazawa Masamoto
• Kanno Tohru

Classifications

• H04N25/677

  for reducing the column or line fixed pattern noise · CPC title

• H04N25/671 Primary

  for non-uniformity detection or correction · CPC title

• H04N25/616 Primary

  involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling · CPC title

• H04N25/78

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

• G01J2001/444

  Compensating; Calibrating, e.g. dark current, temperature drift, noise reduction or baseline correction; Adjusting · CPC title