Radiation imaging apparatus and radiation imaging system

Patent metadata

Field	Value
Publication number	US-9423512-B2
Application number	US-201414189249-A
Country	US
Kind code	B2
Filing date	Feb 25, 2014
Priority date	Feb 28, 2013
Publication date	Aug 23, 2016
Grant date	Aug 23, 2016

Abstract

A radiation imaging apparatus includes a pixel array having pixels, a bias line applying a bias potential to converters of the pixels, a detection circuit which detects a current flowing to the bias line, and a control unit which detects a start of radiation irradiation to the pixel array based on an output from the detection circuit and controls a charge accumulation operation of the pixels in accordance with the detection. The detection circuit includes a differential amplifier circuit and a feedback path, and applies a potential corresponding to a reference bias potential to the bias line. The differential amplifier circuit includes a first input terminal receiving the reference bias potential, a second input terminal connected to the bias line, and an output terminal, and the feedback path connects the output terminal and the second input terminal.

First claim

What is claimed is:

1. A radiation imaging apparatus comprising:
a pixel array in which a plurality of pixels are arrayed, each of the plurality of pixels including a converter configured to accumulate charges corresponding to radiation;
a bias line configured to apply a bias potential to the converters of the plurality of pixels;
a detection circuit configured to detect a current flowing to the bias line; and
a control unit configured to detect a start of radiation irradiation to the pixel array based on an output from the detection circuit and configured to control a charge accumulation operation of the plurality of pixels in accordance with the detection of the start of radiation irradiation,
wherein the detection circuit includes a differential amplifier circuit and a feedback path and is configured to apply a potential corresponding to a reference bias potential to the bias line,
the differential amplifier circuit includes a first input terminal to which the reference bias potential is applied, a second input terminal to which the bias line is connected, and an output terminal, and the feedback path connects the output terminal and the second input terminal, and
an impedance of the feedback path in a detection operation of detecting radiation irradiation is higher than the impedance of the feedback path in a readout operation of a signal from the pixel array.

2. The apparatus according to claim 1 , wherein the control unit controls the impedance of the feedback path based on the output from the detection circuit.

3. The apparatus according to claim 2 , wherein the control unit detects an end of radiation irradiation to the pixel array based on the output from the detection circuit, and makes the impedance of the feedback path low in accordance with the detection of the end of radiation irradiation.

4. The apparatus according to claim 3 , further comprising a readout circuit configured to read out a signal of a selected pixel out of the plurality of pixels,
wherein the control unit makes the impedance of the feedback path low during a period in which the readout circuit is reset for the first time after detection of the end of radiation irradiation to the pixel array.

5. The apparatus according to claim 2 , wherein the control unit makes the impedance of the feedback path low in accordance with detection of the start of radiation irradiation to the pixel array.

6. The apparatus according to claim 1 , wherein the control unit makes the impedance of the feedback path high in accordance with an end of the readout operation.

7. The apparatus according to claim 1 , wherein the feedback path includes a plurality of paths that connect the output terminal and the second input terminal, and
the control unit controls the impedance of the feedback path by selecting a path to be enabled out of the plurality of paths.

8. The apparatus according to claim 7 , wherein the plurality of paths include a path including a resistor and a path formed from an electrically conductive line.

9. The apparatus according to claim 8 , wherein the path including the resistor further includes a capacitor connected in parallel to the resistor.

10. The apparatus according to claim 1 , wherein the differential amplifier circuit and the feedback path form a current-voltage conversion amplifier, and
the detection circuit further includes a voltage amplifier configured to amplify an output of the current-voltage conversion amplifier.

11. A radiation imaging system comprising:
a radiation imaging apparatus as claimed in claim 1 ; and
a processor configured to process a signal output from the radiation imaging apparatus.

Assignees

• Canon Kk

Inventors

• Sato Eriko
• Kameshima Toshio
• Yagi Tomoyuki
• Takenaka Katsuro
• Okada Hideyuki
• Sato Sho
• Iwashita Atsushi
• Ryu Takuya

Classifications

• G01T1/17 Primary

  Circuit arrangements not adapted to a particular type of detector {(pulse-selection circuits H03K, G01R)} · CPC title

• H04N23/30 Primary

  for generating image signals from X-rays · CPC title

• A61B6/4225

  using image intensifiers · CPC title

• A61B6/4233

  using matrix detectors · CPC title

• A61B6/4208 Primary

  characterised by using a particular type of detector · CPC title