Photoelectric converter and radiation reader

• US 20050206764A1
• Filed: 02/25/2005
• Published: 09/22/2005
• Est. Priority Date: 02/20/1998
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kobayashi, Isao, Morishita, Masakazu
• Granted Patent: US 7,724,295 B2
• Time in Patent Office: Days
• US Class Current: 348/308
• CPC Class Codes: G01T 1/247 Detector read-out circuitry for processing gain or off-set correction H04N
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14659 Direct radiation imagers structures
• CPC Class Codes: H01L 27/14663 Indirect radiation imagers, e.g. using luminescent members
• CPC Class Codes: H01L 27/14676 X-ray, gamma-ray or corpuscular radiation imagers measuring X-, gamma- or corpuscular radiation G01T1/00
• CPC Class Codes: H01L 27/14692 Thin film technologies, e.g. amorphous, poly, micro- or nanocrystalline silicon
• CPC Class Codes: H04N 25/30 for transforming X-rays into image signals
• CPC Class Codes: H04N 25/60 Noise processing, e.g. detecting, correcting, reducing or removing noise
• CPC Class Codes: H04N 25/616 involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling
• CPC Class Codes: H04N 25/623 by evacuation via the output or reset lines
• CPC Class Codes: H04N 25/65 applied to reset noise, e.g. KTC noise related to CMOS structures by techniques other than CDS
• CPC Class Codes: H04N 25/67 applied to fixed-pattern noise, e.g. non-uniformity of response
• CPC Class Codes: H04N 25/671 for non-uniformity detection or correction
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/78 Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters
• CPC Class Codes: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30

Abstract

A radiation reader including a conversion device, and a method of driving the radiation reader. The conversion device includes (a) a pixel including a conversion device for converting an incident radiation into an electric charge, and (b) a reading circuit including at least one field effect transistor for reading the electric charge from the pixel in an amplifying manner as a signal containing a noise. The reading circuit includes first storage means for storing the signal containing the noise, second storage means for storing the noise, and processing means for deriving an output signal not containing the noise based on a first output from the first storage means and a second output from the second storage means.

Claims

1-21. -21. (canceled)

22. A radiation reader comprising:

a conversion device comprising (a) a pixel including a conversion device for converting an incident radiation into an electric charge, and (b) a reading circuit including at least one field effect transistor for reading the electric charge from the pixel in an amplifying manner as a signal containing a noise,

wherein the reading circuit comprises first storage means for storing the signal containing the noise, second storage means for storing the noise, and processing means for deriving an output signal not containing the noise based on a first output from the first storage means and a second output from the second storage means.

23. The radiation reader according to claim 22, wherein the reading circuit has a gate for receiving the electric charge from the pixel, a source and a drain for reading the signal corresponding to the electric charge received by the gate, a selecting switch for selecting the at least one field effect transistor, and reset means for resetting the gate.

24. The radiation reader according to claim 23, wherein the at least one field effect transistor, the selecting switch, and the reset means each comprises a thin film transistor.

25. The radiation reader according to claim 24, wherein the thin film transistor is formed from amorphous silicon.

26. The radiation reader according to claim 24, wherein the thin film transistor is formed from polysilicon.

27. The radiation reader according to claim 22, wherein the conversion device included in the pixel comprises a photoelectric conversion element for converting a light into the electric charge, and a wavelength converter for absorbing the incident radiation and converting the radiation into the light, the light being of a wavelength range which can be detected by the photoelectric conversion element.

28. A method for driving a radiation reader comprising a conversion device comprising (a) a pixel including a conversion device for converting an incident radiation into an electric charge, (b) a reading circuit including at least one field effect transistor for reading the electric charge from the pixel in an amplifying manner as a signal containing a noise, (c) first storage means, (d) second storage means, and (e) processing means, comprising the steps of:

(i) converting the incident radiation into the electric charge by the conversion device included in the pixel, and storing the electric charge in the pixel;

(ii) reading by the field effect transistor the electric charge in an amplifying manner as the signal containing the noise, and storing the signal containing the noise in the first storage means;

(iii) storing the noise in the second storage means; and

(iv) producing a reading signal without including the noise based on a first output from the first storage means and a second output from the second storage means.

29. The method according to claim 28, wherein the conversion device included in the pixel comprises a photoelectric conversion element for converting a light into the electric charge, and a wavelength converter for absorbing the incident radiation and converting it into the light, the light being of a wavelength range which can be detected by the photoelectric conversion element, and wherein step (i) includes absorbing the incident radiation into the wavelength converter, converting the radiation into the light, converting the light into the electric charge by the photoelectric conversion element, and storing the electric charge in the pixel.

30. A method for reading radiation, comprising the steps of:

converting an incident radiation into an electric charge;

reading the electric charge in an amplifying manner as a signal containing a noise, and storing the signal containing the noise;

storing the noise; and

producing a reading signal not including the noise based on the stored signal containing the noise, and on the stored noise.

31. The method according to claim 30, wherein the converting step includes absorbing the incident radiation, converting the radiation into a light of a detectable wavelength range, and converting the light into the electric charge.