Liquid crystal apparatus

• US 6,046,717 A
• Filed: 06/06/1995
• Issued: 04/04/2000
• Est. Priority Date: 03/05/1987
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Terada, Masahiro, Onitsuka, Yoshihiro, Mihara, Tadashi, Inoue, Hiroshi, Mizutome, Atsushi, Taniguchi, Osamu
• Primary Examiner(s): LAO, LUNYI
• Application Number:
  US08/471,157
• Time in Patent Office: 1,764 Days
• Field of Search: 345/87, 345/94, 345/95, 345/96, 345/103, 345/208, 345/209, 345/210, 359/55, 349/37, 349/47, 349/49-51
• US Class Current: 345/96
• CPC Class Codes: G09G 2310/0224 Details of interlacing
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/065 Waveforms comprising zero voltage phase or pause
• CPC Class Codes: G09G 2320/0209 Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals

Abstract

A liquid crystal apparatus comprises scanning electrodes and data electrodes intersecting with each other to form a pixel at each intersection, and a ferroelectric liquid crystal disposed between the scanning electrodes and data electrodes. The apparatus includes a first unit for applying to the scanning electrodes at least two scanning selection signals in at least two vertical scanning periods; the scanning selection signals having mutually different waveforms and each having a pulse of one or the other voltage polarity with respect to the level of a voltage applied a scanning electrode when it is not selected; and a second unit for applying data pulses to the data electrodes in phase with said pulse of one or the other voltage polarity. The first unit and second unit in combination apply a fore voltage pulse to a pixel on a scanning electrode selected by application of the pulse of one or the other voltage polarity prior to each application of a writing voltage formed by combination of the pulse of one or the other polarity and an information pulse. The fore voltage pulse has a polarity opposite to that of the writing voltage and an amplitude which is 1/2 or less of that of the writing voltage.

Claims

1. A liquid crystal apparatus, comprising:

a liquid crystal panel including scanning electrodes and data electrodes intersecting each other to form an electrode matrix, and a chiral smectic liquid crystal disposed to form a pixel at each intersection of the scanning electrodes and the data electrodes; and

drive means including (a) first means for applying a first scanning selection signal to the scanning electrodes, the first scanning selection signal comprising a voltage signal of a first polarity in a first phase and a voltage signal of a second polarity in a second phase, and (b) second means for applying a second scanning selection signal to the scanning electrodes, the second scanning selection signal comprising a voltage signal of the second polarity in the first phase and a voltage signal of the first polarity in the second phase,

said first means and second means being driven alternately in a same one vertical scanning period to apply the first scanning selection signal and the second scanning selection signal alternately, respectively, and sequentially to mutually adjacent scanning electrodes,

the first and second polarity being defined with respect to a voltage level applied to a non-selected scanning electrode which does not receive any of the first and second scanning selection signals, and

the first phase being longer than the second phase.

2. A driving method for a liquid crystal panel including scanning electrodes and data electrodes intersecting each other to form an electrode matrix, and a liquid crystal having a memory characteristic disposed to form a pixel at each intersection of the scanning electrodes and the data electrodes, said driving method comprising:

applying a first scanning selection signal and a second scanning selection signal alternately, respectively, and sequentially to mutually adjacent scanning electrodes in a same one vertical scanning operation,

the first scanning selection signal comprising a first voltage signal at a first phase and a second voltage signal at a second phase,

the second scanning selection signal comprising a third voltage signal at a first phase and a fourth voltage signal at a second phase, and

the first to fourth voltage signals having mutually different voltage waveforms.

3. A driving method according to claim 2, wherein the liquid crystal having a memory characteristic is a chiral smectic liquid crystal.

4. A driving method for a liquid crystal panel including scanning electrodes and data electrodes intersecting each other to form an electrode matrix, and a liquid crystal having a memory characteristic disposed to form a pixel at each intersection of the scanning electrodes and the data electrodes, said driving method comprising:

applying a first scanning selection signal and a second scanning selection signal alternately, respectively, and sequentially to mutually adjacent scanning electrodes in a same one vertical scanning period,

the first scanning selection signal comprising a first voltage signal at a first phase and a second voltage signal at a second phase,

the second scanning selection signal comprising a voltage signal of a polarity opposite to that of the first voltage signal at the first phase and a voltage signal of a polarity opposite to that of the second voltage signal at the second phase.

5. A driving method according to claim 4, wherein the liquid crystal having a memory characteristic is a chiral smectic liquid crystal.

6. A driving method for a liquid crystal panel including scanning electrodes and data electrodes intersecting each other to form an electrode matrix, and a liquid crystal having a memory characteristic disposed to form a pixel at each intersection of the scanning electrodes and the data electrodes, said driving method comprising the steps of:

applying a first scanning selection signal and a second scanning selection signal alternately, respectively, and sequentially to mutually adjacent scanning electrodes in a same one vertical scanning period; and

applying the second scanning selection signal to the scanning electrodes having received the first scanning selection signal in the one vertical scanning period, and applying the first scanning selection signal to the scanning electrodes having received the second scanning selection signal in the one vertical scanning period, in another vertical scanning period,

the first scanning selection signal comprising a first voltage signal at a first phase and a second voltage signal at a second phase,

the second scanning selection signal comprising a third voltage signal at a first phase and a fourth voltage signal at a second phase,

the first to fourth voltage signals having mutually different voltage waveforms.

7. A driving method according to claim 6, wherein the liquid crystal having a memory characteristic is a chiral smectic liquid crystal.

8. A driving method for a liquid crystal panel including scanning electrodes and data electrodes intersecting each other to form an electrode matrix, and a liquid crystal having a memory characteristic disposed to form a pixel at each intersection of the scanning electrodes and the data electrodes, said driving method comprising the steps of:

applying a first scanning selection signal and a second scanning selection signal alternately, respectively, and sequentially to mutually adjacent scanning electrodes in same one vertical scanning period; and

applying the second scanning selection signal to the scanning electrodes having received the first scanning selection signal in the one vertical scanning operation, and applying the first scanning selection signal to the scanning electrodes having received the second scanning selection signal in the one vertical scanning period, in another vertical scanning period,

the first scanning selection signal comprising a first voltage signal at a first phase and a second voltage signal at a second phase,

the second scanning selection signal comprising a voltage signal of a polarity opposite to that of the first voltage signal at the first phase and a voltage signal of a polarity opposite to that of the second voltage signal at the second phase.

9. A driving method according to claim 8, wherein the liquid crystal having a memory characteristic is a chiral smectic liquid crystal.