Patent US4981340A successfully refreshed from Google Patents.
US4981340A
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Method and apparatus for readout of information from display panel
Assignee: Canon Inc
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Filing: 1989-07-07
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Granted: 1991-01-01
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Expires: 2009-07-07
Abstract
Abstract A display panel comprises a liquid crystal device including a pixel which comprises opposite electrodes and a ferroelectric liquid crystal disposed therebetween, and optical detection means. The written state of the pixel, i.e., the written information on the display panel, is read out by applying a detection signal voltage to the pixel and detecting a polarization current, if any, caused by the application of the voltage.
Inventors
- 👤 Katsumi Kurematsu
- 👤 Junichiro Kanbe
- 👤 Tsutomu Toyono
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 04:14
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/01; G06F3/03; G06F3/041; G06F3/0412; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3622; G09G3/3629; G11; G11C; G11C11/00; G11C11/21; G11C11/22; G11C7/00; G11C7/005; G09G2310/00; G09G2310/06; G09G2310/066
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
186 words
An information readout method for a display panel which comprises a liquid crystal device including a plurality of scanning lines and data lines, wherein one pixel formed at the intersection of the scanning line and the data line and a ferroelectric liquid crystal disposed therebetween, said method comprising the steps of: applying a detection signal voltage to the pixel and a reference pixel; and detecting a current waveform having a disturbance corresponding to a polarization inversion current caused by the application of the detection signal voltage, converting the current waveform and a reference detection current obtained from the reference pixel to two voltage waveforms and comparing the two voltage waveforms to provide a disturbed voltage waveforms corresponding to the disturbance of the inversion current, and detecting the disturbed voltage waveform, thereby to read out the written state of the pixel, wherein the detection signal voltage comprises a rising voltage pulse or a falling voltage pulse sufficient to cause an inversion of the ferroelectric liquid crystal from one orientation state to another orientation state at a voltage less than a maximum voltage of the detection signal voltage.
Claim 2
Dependent Claim
186 words
An information readout method for a display panel which comprises a liquid crystal device including a plurality of scanning lines and data lines, wherein one pixel formed at the intersection of the scanning line and the data line and a ferroelectric liquid crystal disposed therebetween, said method comprising the steps of: applying a detection signal voltage to the pixel and a reference pixel; and detecting a current waveform having a disturbance corresponding to a polarization inversion current caused by the application of the detection signal voltage, converting the current waveform and a reference detection current obtained from the reference pixel to two voltage waveforms and comparing the two voltage waveforms to provide a disturbed voltage waveforms corresponding to the disturbance of the inversion current, and detecting the disturbed voltage waveform, thereby to read out the written state of the pixel, wherein the detection signal voltage comprises a rising voltage pulse or a falling voltage pulse sufficient to cause an inversion of the ferroelectric liquid crystal from one orientation state to another orientation state at a voltage less than a maximum voltage of the detection signal voltage.
Claim 3
Dependent Claim
29 words
A method according to claim 1, wherein the scanning lines or data lines associated with the pixels in the rows not supplied with the detection signal voltage are grounded.
Claim 4
Dependent Claim
23 words
A method according to claim 1, wherein both the scanning lines and the data lines each not associated with the readout are grounded.
Claim 5
Dependent Claim
17 words
A method according to claim 1, wherein said ferroelectric liquid crystal comprises a chiral smectic liquid crystal.
Claim 6
Dependent Claim
32 words
A method according to claim 4, wherein said chiral smectic liquid crystal is disposed in a layer thin enough to release its own helical structure in the absence of an electric field.
Claim 7
Dependent Claim
182 words
An information readout apparatus comprising: a display panel comprising a liquid crystal device including a plurality of scanning lines and data lines, wherein one pixel formed at the intersection of the scanning line and the data line and a ferroelectric liquid crystal disposed therebetween; means for applying a detection signal voltage to the pixel and a reference pixel; and means for detecting a current waveform having a disturbance corresponding to a polarization inversion current caused by the application of the detection signal voltage, converting the current waveform and a reference detection current obtained from the reference pixel to two voltage waveforms and comparing the two voltage waveforms to provide a disturbed voltage waveform corresponding to the disturbance of the inversion current, and detecting the disturbed voltage waveform, thereby to readout the written state of the pixel, wherein the detection signal voltage comprises a rising voltage pulse or a falling voltage pulse sufficient to cause an inversion of the ferroelectric liquid crystal from one orientation state to another orientation state at a voltage less than a maximum voltage of said detecting signal voltage.
Claim 8
Dependent Claim
182 words
An information readout apparatus comprising: a display panel comprising a liquid crystal device including a plurality of scanning lines and data lines, wherein one pixel formed at the intersection of the scanning line and the data line and a ferroelectric liquid crystal disposed therebetween; means for applying a detection signal voltage to the pixel and a reference pixel; and means for detecting a current waveform having a disturbance corresponding to a polarization inversion current caused by the application of the detection signal voltage, converting the current waveform and a reference detection current obtained from the reference pixel to two voltage waveforms and comparing the two voltage waveforms to provide a disturbed voltage waveform corresponding to the disturbance of the inversion current, and detecting the disturbed voltage waveform, thereby to readout the written state of the pixel, wherein the detection signal voltage comprises a rising voltage pulse or a falling voltage pulse sufficient to cause an inversion of the ferroelectric liquid crystal from one orientation state to another orientation state at a voltage less than a maximum voltage of said detecting signal voltage.
Claim 9
Dependent Claim
29 words
An apparatus according to claim 6, wherein the scanning lines or data lines associated with the pixels in the rows not supplied with the detection signal voltage are grounded.
Claim 10
Dependent Claim
23 words
An apparatus according to claim 6, wherein both the scanning lines and the data lines each not associated with the readout are grounded.
Claim 11
Dependent Claim
17 words
An apparatus according to claim 6, wherein said ferroelectric liquid crystal comprises a chiral smectic liquid crystal.
Claim 12
Dependent Claim
32 words
An apparatus according to claim 9, wherein said chiral smectic liquid crystal is disposed in a layer thin enough to release its own helical structure in the absence of an electric field.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1993-12-31 | 1994-07-02 | 1995-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-31 | 1998-07-02 | 1999-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-31 | 2002-07-02 | 2003-01-01 | $7700.00 | Window Closed / Lapsed |