US5227900A
Expired / Lapsed
US
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Method of driving ferroelectric liquid crystal element
Assignee: Canon Inc
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Filing: 1991-03-19
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Granted: 1993-07-13
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Expires: 2011-03-19
Abstract
Abstract A method of driving a liquid crystal display element in which a switching element is provided for each of pixel electrodes arranged in a matrix manner and a ferroelectric liquid crystal is sandwiched between the pixel electrodes and a counter electrode includes the steps of applying a reset voltage for resetting the entire pixel to a first stable state of the ferroelectric liquid crystal across the pixel electrode and the counter electrode, partially transiting the pixel to a second stable state by a tone signal voltage having a pole opposite to that of the reset voltage, and reversing the pole of the reset voltage every predetermined period. Assuming that a state reverse ratio of the ferroelectric liquid crystal is T(V)% when the tone signal voltage is V, a tone signal voltage V 1 after negative resetting and a corresponding tone signal voltage -V 2 after positive resetting satisfy the following relation: T(V.sub.1)+T(V.sub.2)=100
Inventors
- 👤 Yutaka Inaba
- 👤 Katsumi Kurematsu
- 👤 Shuzo Kaneko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:47
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3648; G09G3/3651; G09G3/367; G09G2310/00; G09G2310/02; G09G2310/0243; G09G2310/0251; G09G2310/06; G09G2310/061; G09G3/2007; G09G3/2011; G09G3/207; G09G3/3614
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
170 words
A method of driving a liquid crystal display element in which a switching element is provided for each of pixel electrodes arranged in a matrix manner and a ferroelectric liquid crystal is sandwiched between said pixel electrodes and a counter electrode, wherein the method displays a gradational picture on the display element through one cycle scanning and comprises the steps of: applying a reset voltage for resetting the entire pixel to a first stable state of said ferroelectric liquid crystal across said pixel electrode and said counter electrode; partially transiting said pixel to a second stable state by a tone signal voltage having an opposite polarity to that of the reset voltage; and reversing the polarity of the reset voltage every predetermined period, wherein if a state reverse ratio of said ferroelectric liquid crystal is indicated as T(V) when the tone signal voltage is V, a tone signal voltage V 1 after negative resetting and a corresponding tone signal voltage -V 2 after positive resetting satisfy the following relation: T(V.sub.1)+T(V.sub.2)=100.
Claim 2
Independent Claim
170 words
A method of driving a liquid crystal display element in which a switching element is provided for each of pixel electrodes arranged in a matrix manner and a ferroelectric liquid crystal is sandwiched between said pixel electrodes and a counter electrode, wherein the method displays a gradational picture on the display element through one cycle scanning and comprises the steps of: applying a reset voltage for resetting the entire pixel to a first stable state of said ferroelectric liquid crystal across said pixel electrode and said counter electrode; partially transiting said pixel to a second stable state by a tone signal voltage having an opposite polarity to that of the reset voltage; and reversing the polarity of the reset voltage every predetermined period, wherein if a state reverse ratio of said ferroelectric liquid crystal is indicated as T(V) when the tone signal voltage is V, a tone signal voltage V 1 after negative resetting and a corresponding tone signal voltage -V 2 after positive resetting satisfy the following relation: T(V.sub.1)+T(V.sub.2)=100.
Claim 3
Dependent Claim
17 words
A method according to claim 1, wherein the predetermined period is a scanning period of one frame.
Claim 4
Dependent Claim
16 words
A method according to claim 1, wherein reset voltages of neighboring scanning lines have opposite poles.
Claim 5
Dependent Claim
16 words
A method according to claim 1, wherein said first stable state corresponds to a black status.
Claim 6
Dependent Claim
171 words
A ferroelectric liquid crystal device for displaying a gradational image picture and having a switching element provided for each of pixel electrodes arranged in a matrix array and ferroelectric liquid crystal interposed between opposite electrodes, comprising: means for alternately applying a reset voltage and a tone signal voltage to the opposite electrodes, the reset voltage being a voltage of resetting the whole pixels into a first stable state and the tone signal voltage being a voltage in an opposite polarity to the reset voltage and transitting part of the pixels into a second stable state; means for reversing the polarity of the reset voltage at every predetermined period; and means for reversing the polarity of the tone signal voltage at every predetermined period, and wherein if a state reverse ratio of said ferroelectric liquid crystal is indicated as T(V) when the tone signal voltage is V, a tone signal voltage V 1 after negative resetting and a corresponding tone signal voltage -V 2 after positive resetting satisfy the following relation: T(V.sub.1)+T(V.sub.2)=100.
Claim 7
Dependent Claim
171 words
A ferroelectric liquid crystal device for displaying a gradational image picture and having a switching element provided for each of pixel electrodes arranged in a matrix array and ferroelectric liquid crystal interposed between opposite electrodes, comprising: means for alternately applying a reset voltage and a tone signal voltage to the opposite electrodes, the reset voltage being a voltage of resetting the whole pixels into a first stable state and the tone signal voltage being a voltage in an opposite polarity to the reset voltage and transitting part of the pixels into a second stable state; means for reversing the polarity of the reset voltage at every predetermined period; and means for reversing the polarity of the tone signal voltage at every predetermined period, and wherein if a state reverse ratio of said ferroelectric liquid crystal is indicated as T(V) when the tone signal voltage is V, a tone signal voltage V 1 after negative resetting and a corresponding tone signal voltage -V 2 after positive resetting satisfy the following relation: T(V.sub.1)+T(V.sub.2)=100.
Claim 8
Dependent Claim
20 words
A ferroelectric liquid crystal device according to claim 5, wherein the predetermined period is a scanning period of one frame.
Claim 9
Dependent Claim
19 words
A ferroelectric liquid crystal device according to claim 5, wherein reset voltages of neighboring scanning lines have opposite poles.
Claim 10
Dependent Claim
19 words
A ferroelectric liquid crystal device according to claim 5, wherein said first stable state corresponds to a black status.
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