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EP0448032A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Method of driving ferroelectric liquid crystal element and ferroelectric liquid crystal display

Assignee: Canon Inc
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Filing: 1991-03-19
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Granted: —
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Expires: 2011-03-19
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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 V1 after negative resetting and a corresponding tone signal voltage -V2 after positive resetting satisfy the following relation: T(V1) + T(V2) = 100 <IMAGE>

Inventors

  • 👤 Yutaka C/O Canon Kabushiki Kaisha Inaba
  • 👤 Katsumi C/O Canon Kabushiki Kaisha Kurematsu
  • 👤 Shuzo C/O Canon Kabushiki Kaisha Kaneko

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-04 10:58
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: 8
Claim 1
Independent Claim 155 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, comprising 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 a pole opposite to that of the reset voltage; and reversing the pole of the reset voltage every predetermined period, wherein assuming that a state reverse ratio of said ferroelectric liquid crystal is T(V)% when the tone signal voltage is V, a tone signal voltage V₁ after negative resetting and a corresponding tone signal voltage -V₂ after positive resetting satisfy the following relation: T(V₁) + T(V₂) = 100
Claim 2
Dependent Claim 17 words
A method according to claim 1, wherein the predetermined period is a scanning period of one frame.
Claim 3
Dependent Claim 16 words
A method according to claim 1, wherein reset voltages of neighboring scanning lines have opposite poles.
Claim 4
Dependent Claim 16 words
A method according to Claim 1, wherein said first stable state corresponds to a black status.
Claim 5
Dependent Claim 165 words
A ferroelectric liquid crystal device 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 resent 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 transiting part of the pixels into a second stable state; means for reversing the porality of the reset voltage at every predetermined period; and means for reversing the porality of the tone signal voltage at every predetermined period, and wherein assuming that a state reverse ratio of said ferroelectric liquid crystal is T(V)% when the tone signal voltage is V, a tone signal voltage V₁ after negative resetting and a corresponding tone signal voltage -V₂ after positive resetting satisfy the following relation: T(V₁) + T(V₂) = 100
Claim 6
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 7
Dependent Claim 19 words
A ferroelectric liquid crystal device according to claim 5, wherein reset voltages of neighboring scanning lines have opposite poles.
Claim 8
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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