US5774180A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Image sensor capable of producing an image signal free from an afterimage
Assignee: Fujifilm Business Innovation Corp
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Filing: 1996-03-28
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Granted: 1998-06-30
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Expires: 2016-03-28
Abstract
Abstract Charges photoelectrically generated in reversely biased photodiodes are sequentially transferred through respective thin-film transistors to a driver IC. A plurality of capacitors are connected to the anodes of the respective photodiodes. During a charge reading period, a variable voltage generation circuit supplies the cathode of each photodiode with a first voltage that is higher than an anode voltage to reversely bias the photodiode. During a predetermined period after the charge reading period, the variable voltage generation circuit supplies the cathode of the photodiode with a second voltage that is lower than the first voltage and a gate pulse generation circuit supplies, through the associated capacitor, the anode of the photodiode with a third voltage that allows the photodiode to be forwardly biased.
Inventors
- 👤 Tsutomu Abe
- 👤 Hiroyuki Miyake
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:00
CPC Classifications
H; H04; H04N; H04N25/00; H04N25/60; H04N25/62; H04N25/626; H04N25/70; H04N25/701; H04N25/76; H04N25/767
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
161 words
An image sensor in which charges photoelectrically generated in a plurality of reversely biased photodiodes are read out to produce an image signal, said image sensor comprising: a plurality of capacitors connected to anodes of the respective photodiodes; main bias means for supplying to a cathode of each of the photodiodes a first voltage that is higher than a voltage of an anode of the photodiode during a period of reading a charge of the photodiode and for supplying to the cathode of each of the photodiodes a second voltage that is lower than the first voltage, during a predetermined period after the charge reading period, and for supplying the first voltage to the cathode of each of the photodiodes after a lapse of the predetermined period; and auxiliary bias means for supplying to the anodes of the photodiodes, through an associated one of the capacitors during the predetermined period, a third voltage that allows the photodiodes to be forwardly biased.
Claim 2
Dependent Claim
161 words
An image sensor in which charges photoelectrically generated in a plurality of reversely biased photodiodes are read out to produce an image signal, said image sensor comprising: a plurality of capacitors connected to anodes of the respective photodiodes; main bias means for supplying to a cathode of each of the photodiodes a first voltage that is higher than a voltage of an anode of the photodiode during a period of reading a charge of the photodiode and for supplying to the cathode of each of the photodiodes a second voltage that is lower than the first voltage, during a predetermined period after the charge reading period, and for supplying the first voltage to the cathode of each of the photodiodes after a lapse of the predetermined period; and auxiliary bias means for supplying to the anodes of the photodiodes, through an associated one of the capacitors during the predetermined period, a third voltage that allows the photodiodes to be forwardly biased.
Claim 3
Dependent Claim
34 words
The image sensor of claim 1, further comprising a plurality of thin-film transistors connected to the anodes of the respective photodiodes, for sequentially transferring the charges of the photodiodes during the charge reading periods.
Claim 4
Independent Claim
108 words
A method for driving an image sensor in which charges photoelectrically generated in a plurality of reversely biased photodiodes are read out to produce an image signal, said drive method comprising the steps of: reading out charges from each of the photodiodes during a reading period while the photodiodes are reversely biased; forwardly biasing the photodiodes during another period after the reading period; and reversely biasing the photodiodes after said another period, wherein the photodiodes are kept reversely biased by grounding anodes of the photodiodes through a capacitance and supplying cathodes of the photodiodes with a positive voltage that is higher than forward voltage drops of the photodiodes.
Claim 5
Independent Claim
108 words
A method for driving an image sensor in which charges photoelectrically generated in a plurality of reversely biased photodiodes are read out to produce an image signal, said drive method comprising the steps of: reading out charges from each of the photodiodes during a reading period while the photodiodes are reversely biased; forwardly biasing the photodiodes during another period after the reading period; and reversely biasing the photodiodes after said another period, wherein the photodiodes are kept reversely biased by grounding anodes of the photodiodes through a capacitance and supplying cathodes of the photodiodes with a positive voltage that is higher than forward voltage drops of the photodiodes.
Claim 6
Dependent Claim
49 words
The drive method of claim 3, wherein a first feedthrough voltage is a function of the capacitance and the capacitance is selected to cause the first feedthrough voltage to be larger than a second feedthrough voltage caused by application of the reset voltage to the cathodes of the photodiodes.
Claim 7
Dependent Claim
30 words
The drive method of claim 4, wherein the capacitance is provided by parallel electrode plates, and the first feedthrough voltage is determined by opposing areas of the parallel electrode plates.
Claim 8
Dependent Claim
20 words
The drive method of claim 4, wherein the first feedthrough voltage is adjusted by a magnitude of the positive pulse.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-06-29 | 2001-12-29 | 2002-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-06-29 | 2005-12-29 | 2006-06-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-06-29 | 2009-12-29 | 2010-06-30 | $7700.00 | Window Closed / Lapsed |