Liquid crystal display device and method for driving the same

• US 5,691,783 A
• Filed: 06/30/1994
• Issued: 11/25/1997
• Est. Priority Date: 06/30/1993
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Tamai, Kazuhiko, Numao, Takaji, Shinomiya, Tokihiko, Tagawa, Akira, Koden, Mitsuhiro
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US08/269,450
• Time in Patent Office: 1,244 Days
• Field of Search: 359/54, 359/63, 359/56, 359/58, 359/59, 359/82, 359/100, 345/92, 345/206, 345/97, 345/93, 345/208, 349/37, 349/38, 349/48, 349/100, 349/96, 349/143, 349/172
• US Class Current: 349/48
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3651 using multistable liquid crystals, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes

Abstract

A ferroelectric liquid crystal display device includes a plurality of pixels, and each of the plurality of pixels includes ferroelectric liquid crystal material having ferroelectric liquid crystal molecules therein capable of being aligned in a first stable alignment state, whereby a principal axis of each of the molecules is aligned at an angle ω with respect to a central line, and of being aligned in a second stable alignment state, whereby the principal axis of each of the molecules is aligned at an angle -ω with respect to the central line, and a pair of polarizers on opposite sides of the ferroelectric liquid crystal material, a polarizing axis of one of the polarizers being substantially aligned with the central line.

Claims

1. A ferroelectric liquid crystal display device, comprising:

a plurality of pixels, each including;

ferroelectric liquid crystal material having ferroelectric liquid crystal molecules therein, capable of being aligned in a first stable alignment state, whereby a principal axis of each of the molecules is aligned at an angle ω

with respect to a central line, and of being aligned in a second stable alignment state, whereby the principal axis of each of the molecules is aligned at an angle -ω

with respect to the central line; and

a pair of polarizers on opposite sides of the ferroelectric liquid crystal material, a polarizing axis of one of the polarizers being substantially aligned with the central line,

wherein the plurality of pixels are arranged in a matrix, and each of the plurality of pixels is connected to a driving circuit including;

a first switching device for controlling an output of a driving signal;

a charge-retaining capacitance for receiving an output from the first switching device; and

a second switching device for receiving the output received by the charge-retaining capacitance from the first switching device as a switching control signal for controlling an output of a charge for display sent from a display power source and for sending the charge for display to establish an arbitrary field across the ferroelectric liquid crystal molecules in the corresponding pixel, and

wherein the driving circuit comprises

a third switching device, connected between the second switching device and the pixel, for controlling an output of the charge for display sent from the second switching device to the corresponding pixel, wherein

the first switching devices are activated line by line to store a prescribed charge in each of the charge-retaining capacitances, and thereafter a plane-scanning switching control signal is supplied to each of the third switching devices to update the charges for display stored in the pixels substantially simultaneously.

2. A ferroelectric liquid crystal display device according to claim 1, further comprising two substrates sandwiching the ferroelectric liquid crystal material, and one of the two substrates is formed of single crystalline silicon and the other substrate is formed of a light-transmitting material.

3. A ferroelectric liquid crystal display device, comprising:

a plurality of pixels, each including;

ferroelectric liquid crystal material having ferroelectric liquid crystal molecules therein, capable of being aligned in a first stable alignment state, whereby a principal axis of each of the molecules is aligned at an angle ω

with respect to a central line, and of being aligned in a second stable alignment state, whereby the principal axis of each of the molecules is aligned at an angle -ω

with respect to the central line;

the ferroelectric liquid crystal molecules, in one of the two stable alignment states, are put at a position between the central line and a first tilting axis by application of a voltage in the range between a prescribed positive voltage and a prescribed negative voltage, and

the ferroelectric liquid crystals, in the other stable alignment state, are put at a position between the central line and a second tilting axis by application of a voltage in the range between a prescribed negative voltage and a prescribed positive voltage; and

a pair of polarizers on opposite sides of the ferroelectric liquid crystal material, a polarizing axis of one of the polarizers being substantially aligned with the central line,

wherein the plurality of pixels are arranged in a matrix, and each of the plurality of pixels is connected to a driving circuit including;

a first switching device for controlling an output of a driving signal;

a charge-retaining capacitance for receiving an output from the first switching device; and

a second switching device for receiving the output received by the charge-retaining capacitance from the first switching device as a switching control signal for controlling an output of a charge for display sent from a display power source and for sending the charge for display to establish an arbitrary field across the ferroelectric liquid crystal molecules in the corresponding pixel, and

wherein the driving circuit comprises

a third switching device, connected between the second switching device and the pixel, for controlling an output of the charge for display sent from the second switching device to the corresponding pixel, wherein

the first switching devices are activated line by line to store a prescribed charge in each of the charge-retaining capacitances, and thereafter a plane-scanning switching control signal is supplied to each of the third switching devices to update the charges for display stored in the pixels substantially simultaneously.

4. A ferroelectric liquid crystal display device according to claim 3, further comprising two substrates sandwiching the ferroelectric liquid crystal material, and one of the two substrates is formed of single crystalline silicon and the other substrate is formed of a light-transmitting material.