EP0177275A2
Expired / Lapsed
EP
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Photosensor suited for image sensor
Assignee: Toshiba Corp
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Filing: 1985-09-26
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Granted: —
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Expires: 2005-09-26
Abstract
Abstract A photosensor for realizing an image sensor which can meet the requirements of high resolution, high operation speed and high signal-to-noise ratio is disclosed. The photosensor comprises a circuit substrate (1), a thin film transistor (3) formed on the circuit substrate and an amorphous silicon photodiode (2) formed on the substrate integral with the thin film transistor (3) between the drain and gate electrodes (11, 15) thereof. Also formed on the circuit substrate adjacent to the thin film transistor and photodiode are a charging switch element (4) for coupling the photodiode (2) to a DC power source (27) to charge an inter-electrode capacitance of the photodiode, a charge storage capacitor (6) charged by a channel current of the thin film transistor (3) controlled by an inter-electrode capacitance voltage of the photodiode (2) which varies in response to incident light (20) after the inter-electrode capacitance has been charged, and a detecting switch element (5) for coupling the capacitor to an output amplifier (28). The charging and detecting switch elements are each formed of a thin film transistor.
Inventors
- 👤 Yoshiyuki C/O Patent Division Suda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 06:53
CPC Classifications
H; H10; H10F; H10F39/00; H10F39/10; H10F39/12; H10F39/18; H10F30/00; H10F30/20; H10F30/21; H10F30/22; H10F30/227; H10F39/80; H10K; H10K30/00; H10K30/80; H10K30/81
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
171 words
A photosensor comprising: a circuit substrate (1); a thin film transistor (3) formed on said circuit substrate and having a gate electrode (15) and drain and source electrodes (11, 12) forming a channel therebetween in response to a control voltage applied to said gate electrode, a channel current controlled by said control voltage flowing through said channel; an amorphous silicon photodiode (2) formed on said substrate integral with said thin film transistor (3) between one of said drain and source electrodes and said gate electrode of said thin film transistor, said amorphous silicon photodiode (2) having an inter- electrode capacitance (C); charging means (4, 27) coupled to said photodiode for charging said inter-electrode capacitance of said photodiode (2); and detecting means (5, 6, 28) coupled to said thin film transistor for detecting the channel current of said thin film transistor (3) which is controlled by a voltage across said inter-electrode capacitance of said photodiode (2), the voltage varying in response to incident light (20) after said inter-electrode capacitance has been charged.
Claim 2
Dependent Claim
171 words
A photosensor comprising: a circuit substrate (1); a thin film transistor (3) formed on said circuit substrate and having a gate electrode (15) and drain and source electrodes (11, 12) forming a channel therebetween in response to a control voltage applied to said gate electrode, a channel current controlled by said control voltage flowing through said channel; an amorphous silicon photodiode (2) formed on said substrate integral with said thin film transistor (3) between one of said drain and source electrodes and said gate electrode of said thin film transistor, said amorphous silicon photodiode (2) having an inter- electrode capacitance (C); charging means (4, 27) coupled to said photodiode for charging said inter-electrode capacitance of said photodiode (2); and detecting means (5, 6, 28) coupled to said thin film transistor for detecting the channel current of said thin film transistor (3) which is controlled by a voltage across said inter-electrode capacitance of said photodiode (2), the voltage varying in response to incident light (20) after said inter-electrode capacitance has been charged.
Claim 3
Dependent Claim
62 words
The photosensor according to claim 1, characterized in that said photodiode (2) includes a cathode electrode (16); an anode electrode (18) formed of transparent electrical conductive film; and hydrogenated amorphous silicon film (17) sandwiched between said cathode and anode electrodes, said cathode and anode electrodes being electrically connected to said drain and gate electrodes (11, 15) of said thin film transistor, respectively.
Claim 4
Dependent Claim
62 words
The photosensor according to claim 1, characterized in that said photodiode t2) includes a cathode electrode (16); an anode electrode (18) formed of transparent electrical conductive film; and hydrogenated amorphous silicon film (17) sandwiched between said cathode and anode electrodes, said cathode and anode electrodes being electrically connected to said gate and source electrodes (15, 12) of said thin film transistor, respectively.
Claim 5
Dependent Claim
81 words
The photosensor according to claim 1, characterized in that said charging means comprises a DC power supply (27); and a charging switching element (4) for coupling said DC power supply to said photodiode (2) for charging said inter-electrode capacitance (C) thereof, said charging switching element formed of a thin film transistor formed on said circuit substrate adjacent to said first-mentioned thin film transistor (3) and photodiode (2), and adapted to be turned on and off by an externally supplied control signal.
Claim 6
Dependent Claim
77 words
The photosensor according to claim 1, characterized in that said detecting means includes a charge storage capacitor (6) coupled to said thin film transistor (3) and adapted to be charged by the channel current thereof; an output amplifier (28) for taking out an output signal of said photosensor; and a detecting switching element (5) adapted to be turned on and off by an externally applied control signal to couple said charge storage capacitor to said output amplifier.
Claim 7
Dependent Claim
106 words
The photosensor according to claim 1, characterized in that said detecting means includes a charge storage capacitor (6) coupled to said thin film transistor (3) and adapted to be charged by the channel current thereof; an output amplifier (28) for taking out an output signal of said photosensor; and a detection switching element (5) adapted to be turned on and off by an externally applied control signal to couple said charge storage capacitor to said output amplifier, said detecting switch element being formed of a thin film transistor, and said charge storage capacitor (6) and detecting switch element (5) being formed on said circuit substrate (1).
Claim 8
Dependent Claim
188 words
An image sensor comprising: a circuit substrate (l); and a plurality of photosensors formed in line on said circuit substrate; each of said photosensors comprising: a thin film transistor (3) formed on said circuit substrate (1) and having a gate electrode (15) and drain and source electrodes (ll, 12) forming a channel therebetween in response to a control voltage applied to said gate electrode, a channel current controlled by said control voltage flowing through said channel; an amorphous silicon photodiode (2) formed on said substrate integral with said thin film transistor (3) between one of said drain and source electrodes and said gate electrode of said thin film transistor, said amorphous silicon photodiode (2) having an inter- electrode capacitance; charging means (4, 27) coupled to said photodiode for charging said inter-electrode capacitance of said photodiode (2); and detecting means (5, 6, 28) coupled to said thin film transistor for detecting the channel current flowing through said thin film transistor (3) controlled by a voltage across said inter-electrode capacitance of said photodiode (2), the voltage varying in response to incident light (20) after said inter-electrode capacitance has been charged.
Claim 9
Dependent Claim
188 words
An image sensor comprising: a circuit substrate (l); and a plurality of photosensors formed in line on said circuit substrate; each of said photosensors comprising: a thin film transistor (3) formed on said circuit substrate (1) and having a gate electrode (15) and drain and source electrodes (ll, 12) forming a channel therebetween in response to a control voltage applied to said gate electrode, a channel current controlled by said control voltage flowing through said channel; an amorphous silicon photodiode (2) formed on said substrate integral with said thin film transistor (3) between one of said drain and source electrodes and said gate electrode of said thin film transistor, said amorphous silicon photodiode (2) having an inter- electrode capacitance; charging means (4, 27) coupled to said photodiode for charging said inter-electrode capacitance of said photodiode (2); and detecting means (5, 6, 28) coupled to said thin film transistor for detecting the channel current flowing through said thin film transistor (3) controlled by a voltage across said inter-electrode capacitance of said photodiode (2), the voltage varying in response to incident light (20) after said inter-electrode capacitance has been charged.
References Cited (Backward Citations)
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