US5465168A — Gradation driving method for bistable ferroelectr…

Claim 1

Independent Claim 240 words

A method for driving a liquid crystal display comprising, a liquid crystal cell including a pair of substrates, one of the substrates providing pixel electrodes arranged in a matrix, scanning and signal electrodes and active elements for active matrix control of the pixel electrodes and an orientation control layer thereon, the remaining substrate providing an opposite electrode and an orientation control layer thereon, and a ferroelectric liquid crystal filled in the cell, the ferroelectric liquid crystal being bistable in the cell; and a pair of polarizing plates provided in the state of "cross nicol" on both sides of the liquid crystal cell, the polarizing plates being oriented in such a manner that one of their polarizing directions is consistent with one of extinction positions of the ferroelectric liquid crystal under no electric field, comprising the steps of: applying zero or positive voltages to the signal electrodes in synchronism to an ON operation of the active element responsive to a signal sent from the scanning electrode to form a first frame, and applying zero or negative voltages to the signal electrodes in synchronism to the ON operation of the active element to form a second frame, therewith controlling the magnitudes of the applied voltages to change an apparent tilt angle of the liquid crystal so that said apparent tilt angle assumes both positive and negative values, and combining the first and second frames sequentially to display an image with gray scale.

Claim 2

Independent Claim 240 words

A method for driving a liquid crystal display comprising, a liquid crystal cell including a pair of substrates, one of the substrates providing pixel electrodes arranged in a matrix, scanning and signal electrodes and active elements for active matrix control of the pixel electrodes and an orientation control layer thereon, the remaining substrate providing an opposite electrode and an orientation control layer thereon, and a ferroelectric liquid crystal filled in the cell, the ferroelectric liquid crystal being bistable in the cell; and a pair of polarizing plates provided in the state of "cross nicol" on both sides of the liquid crystal cell, the polarizing plates being oriented in such a manner that one of their polarizing directions is consistent with one of extinction positions of the ferroelectric liquid crystal under no electric field, comprising the steps of: applying zero or positive voltages to the signal electrodes in synchronism to an ON operation of the active element responsive to a signal sent from the scanning electrode to form a first frame, and applying zero or negative voltages to the signal electrodes in synchronism to the ON operation of the active element to form a second frame, therewith controlling the magnitudes of the applied voltages to change an apparent tilt angle of the liquid crystal so that said apparent tilt angle assumes both positive and negative values, and combining the first and second frames sequentially to display an image with gray scale.

Claim 3

Dependent Claim 149 words

The method according to claim 1, wherein the ferroelectric liquid crystal contains at least one of compounds represented by the representative formula (1): ##STR15## (where each of R 1 and R 2 denotes an alkyl or alkoxy group having a carbon number of 3 to 16 which is straight-chained or branched, and each of X 1 , X 2 , X 3 and X 4 denotes a hydrogen or halogen atom, at least one of which denotes a fluorine atom) or by the representative formula (2): ##STR16## (where each of R 3 and R 4 denotes an alkyl or alkoxy group having a carbon number of 3 to 16 which is straight-chained or branched, and each of X 5 , X 6 , X 7 , X 8 , X 9 and X 10 denotes a hydrogen or halogen atom, at least one of which denotes a fluorine atom.)

Claim 4

Dependent Claim 65 words

The method according to claim 2, wherein the ferroelectric liquid crystal satisfies the following relationship: C·Vmax>3·Ps·S where C is an electrostatic capacity of each pixel provided with the pixel electrode; Vmax is a maximum voltage applied to the pixel through the active element; S is an area of the pixel; and Ps is an absolute value of the spontaneous polarization of the ferroelectric liquid crystal.

Claim 5

Dependent Claim 17 words

The method according to claim 3, wherein the absolute value Ps is 5 nC/cm 2 or less.

Claim 6

Dependent Claim 39 words

The method according to claim 1, wherein the ferroelectric liquid crystal is a short pitch ferroelectric liquid crystal having a spiral pitch shorter than a space between the substrates and a spiral structure to be loosened in the cell.

Claim 7

Dependent Claim 65 words

The method according to claim 1, wherein the ferroelectric liquid crystal satisfies the following relationship: C·Vmax>3·Ps·S where C is an electrostatic capacity of each pixel provided with the pixel electrode; Vmax is a maximum voltage applied to the pixel through the active element; S is an area of the pixel; and Ps is an absolute value of the spontaneous polarization of the ferroelectric liquid crystal.

Claim 8

Dependent Claim 17 words

The method according to claim 6, wherein the absolute value Ps is 5 nC/cm 2 or less.

Claim 9

Dependent Claim 217 words

A line sequential driving method for driving a liquid crystal display comprising: a liquid crystal cell including a pair of substrates, one of the substrate providing scanning electrodes and an orientation control layer thereon, the remaining substrate providing signal electrodes and an orientation control layer thereon, and a ferroelectric liquid crystal filled between the substrates, and a pair of polarizing plates provided in the state of "cross nicol" on both sides of the liquid crystal cell, the polarizing plates being oriented in such a manner that one of their polarizing directions is consistent with one of extinction positions of the ferroelectric liquid crystal under no electric field, comprising the steps of: applying a positive voltage or a negative voltage to a series of electrode groups each comprising a predetermined number of the scanning and/or signal electrodes so that the voltages applied to adjacent groups differ in polarity, to form a first frame, applying a voltage having polarity opposite to that in the first frame to each electrode group to form a second frame, therewith controlling magnitudes of the applied voltages to change an apparent tilt angle of the liquid crystal so that said apparent tilt angle assumes both positive and negative values, and combining the first and second frames sequentially to display an image with gray scale.

Claim 10

Dependent Claim 217 words

A line sequential driving method for driving a liquid crystal display comprising: a liquid crystal cell including a pair of substrates, one of the substrate providing scanning electrodes and an orientation control layer thereon, the remaining substrate providing signal electrodes and an orientation control layer thereon, and a ferroelectric liquid crystal filled between the substrates, and a pair of polarizing plates provided in the state of "cross nicol" on both sides of the liquid crystal cell, the polarizing plates being oriented in such a manner that one of their polarizing directions is consistent with one of extinction positions of the ferroelectric liquid crystal under no electric field, comprising the steps of: applying a positive voltage or a negative voltage to a series of electrode groups each comprising a predetermined number of the scanning and/or signal electrodes so that the voltages applied to adjacent groups differ in polarity, to form a first frame, applying a voltage having polarity opposite to that in the first frame to each electrode group to form a second frame, therewith controlling magnitudes of the applied voltages to change an apparent tilt angle of the liquid crystal so that said apparent tilt angle assumes both positive and negative values, and combining the first and second frames sequentially to display an image with gray scale.

Claim 11

Dependent Claim 21 words

The method according to claim 8, wherein the predetermined number of scanning and/or signal electrodes indicate one scanning and/or signal electrode(s).

Claim 12

Dependent Claim 15 words

The method according to claim 8, wherein the frame is cyclically refreshed at 60 Hz.

Claim 13

Dependent Claim 149 words

The method according to claim 8, wherein the ferroelectric liquid crystal contains at least one of compounds represented by the representative formula (1): ##STR17## (where each of R 1 and R 2 denotes an alkyl or alkoxy group having a carbon number of 3 to 16 which is straight-chained or branched, and each of X 1 , X 2 , X 3 and X 4 denotes a hydrogen or halogen atom, at least one of which denotes a fluorine atom) or by the representative formula (2): ##STR18## (where each of R 3 and R 4 denotes an alkyl or alkoxy group having a carbon number of 3 to 16 which is straight-chained or branched, and each of X 5 , X 6 , X 7 , X 8 , X 9 and X 10 denotes a hydrogen or halogen atom, at least one of which denotes a fluorine atom.)

Claim 14

Dependent Claim 39 words

The method according to claim 8, wherein the ferroelectric liquid crystal is a short pitch ferroelectric liquid crystal having a spiral pitch shorter than a space between the substrates and a spiral structure to be loosened in the cell.

Claim 15

Dependent Claim 241 words

A line sequence driving method for driving an active matrix type liquid crystal display comprising, a liquid crystal cell including a pair of substrates, one of the substrates providing pixel electrodes arranged in a matrix, scanning and signal electrodes and active elements for active matrix control of the pixel electrodes and an orientation control layer thereon, the remaining substrate providing an opposite electrode and an orientation control layer thereon, and a ferroelectric liquid crystal filled in the cell; and a pair of polarizing plates provided in the state of "cross nicol" on both sides of the liquid crystal cell, the polarizing plates being oriented in such a manner that one of their polarizing directions is consistent with one of extinction positions of the ferroelectric liquid crystal under no electric field, comprising the steps of: applying a positive voltage or a negative voltage to a series of electrode groups each comprising a predetermined number of the scanning and/or signal electrodes so that the voltages applied to adjacent electrode groups differ in polarity, to form a first frame, applying a voltage having polarity opposite to that in the first frame to each electrode group to form a second frame, therewith controlling magnitudes of the applied voltages to change an apparent tilt angle of the liquid crystal so that said apparent tilt angle assumes both positive and negative values, and combining the first and second frames sequentially to display an image with gray scale.

Claim 16

Dependent Claim 241 words

A line sequence driving method for driving an active matrix type liquid crystal display comprising, a liquid crystal cell including a pair of substrates, one of the substrates providing pixel electrodes arranged in a matrix, scanning and signal electrodes and active elements for active matrix control of the pixel electrodes and an orientation control layer thereon, the remaining substrate providing an opposite electrode and an orientation control layer thereon, and a ferroelectric liquid crystal filled in the cell; and a pair of polarizing plates provided in the state of "cross nicol" on both sides of the liquid crystal cell, the polarizing plates being oriented in such a manner that one of their polarizing directions is consistent with one of extinction positions of the ferroelectric liquid crystal under no electric field, comprising the steps of: applying a positive voltage or a negative voltage to a series of electrode groups each comprising a predetermined number of the scanning and/or signal electrodes so that the voltages applied to adjacent electrode groups differ in polarity, to form a first frame, applying a voltage having polarity opposite to that in the first frame to each electrode group to form a second frame, therewith controlling magnitudes of the applied voltages to change an apparent tilt angle of the liquid crystal so that said apparent tilt angle assumes both positive and negative values, and combining the first and second frames sequentially to display an image with gray scale.

Claim 17

Dependent Claim 21 words

The method according to claim 13, wherein the predetermined number of scanning and/or signal electrode indicates one scanning and/or signal electrode(s).

Claim 18

Dependent Claim 15 words

The method according to claim 13, wherein the frame is cyclically refreshed at 60 Hz.

Claim 19

Dependent Claim 149 words

The method according to claim 13, wherein the ferroelectric liquid crystal contains at least one of compounds represented by the representative formula (1): ##STR19## (where each of R 1 and R 2 denotes an alkyl or alkoxy group having a carbon number of 3 to 16 which is straight-chained or branched, and each of X 1 , X 2 , X 3 and X 4 denotes a hydrogen or halogen atom, at least one of which denotes a fluorine atom) or by the representative formula (2): ##STR20## (where each of R 3 and R 4 denotes an alkyl or alkoxy group having a carbon number of 3 to 16 which is straight-chained or branched, and each of X 5 , X 6 , X 7 , X 8 , X 9 and X 10 denotes a hydrogen or halogen atom, at least one of which denotes a fluorine atom.)

Claim 20

Dependent Claim 39 words

The method according to claim 13, wherein the ferroelectric liquid crystal is a short pitch ferroelectric liquid crystal having a spiral pitch shorter than a space between the substrates and a spiral structure to be loosened in the cell.

Claim 21

Dependent Claim 65 words

The method according to claim 13, wherein the ferroelectric liquid crystal satisfies the following relationship: C·Vmax>3·Ps·S where C is an electrostatic capacity of each pixel provided with the pixel electrode; Vmax is a maximum voltage applied to the pixel through the active element; S is an area of the pixel; and Ps is an absolute value of the spontaneous polarization of the ferroelectric liquid crystal.

Claim 22

Dependent Claim 17 words

The method according to claim 18, wherein the absolute value Ps is 5 nC/cm 2 or less.

Claim 23

Independent Claim 191 words

A method for driving a liquid crystal display which comprises: a liquid crystal cell including a pair of substrates each having an electrode film and an orientation control layer on each electrode film, and a pair of polarizing plates provided in the state of "cross nicol" on both sides of the liquid crystal cell; comprising the steps of: providing a ferroelectric liquid crystal between the substrates, the ferroelectric liquid crystal showing bistable characteristics having two maximum apparent tilt angles ±Θ and two memory angles ±Θm, where Θ>Θm; aligning one of polarizing directions of the polarizing plates with the angle Θm; applying to the cell an alternating voltage having such a low frequency that an apparent tilt angle of the ferroelectric liquid crystal changes alternatively with respect to the angle Θm and synchronously with the alternating voltage thus having the apparent tilt angle assume both positive and negative values, and controlling a magnitude of the alternating voltage to change each intensity of light transmitted during a half cycle and the next half cycle, whereby an average intensity of light transmitted through the cell per cycle of the applied alternating voltage is controlled.

Claim 24

Independent Claim 191 words

A method for driving a liquid crystal display which comprises: a liquid crystal cell including a pair of substrates each having an electrode film and an orientation control layer on each electrode film, and a pair of polarizing plates provided in the state of "cross nicol" on both sides of the liquid crystal cell; comprising the steps of: providing a ferroelectric liquid crystal between the substrates, the ferroelectric liquid crystal showing bistable characteristics having two maximum apparent tilt angles ±Θ and two memory angles ±Θm, where Θ>Θm; aligning one of polarizing directions of the polarizing plates with the angle Θm; applying to the cell an alternating voltage having such a low frequency that an apparent tilt angle of the ferroelectric liquid crystal changes alternatively with respect to the angle Θm and synchronously with the alternating voltage thus having the apparent tilt angle assume both positive and negative values, and controlling a magnitude of the alternating voltage to change each intensity of light transmitted during a half cycle and the next half cycle, whereby an average intensity of light transmitted through the cell per cycle of the applied alternating voltage is controlled.

Claim 25

Dependent Claim 148 words

The method of claim 20, wherein the ferroelectric liquid crystal contains at least one of compounds represented by the representative formula (1): ##STR21## (where each of R 1 and R 2 denotes an alkyl or alkoxy group having a carbon number of 3 to 16 which is straight-chained or branched, and each of X 1 , X 2 , X 3 and X 4 denotes a hydrogen or halogen atom, at least one of which denotes a fluorine atom) or by the representative formula (2): ##STR22## (where each of R 3 and R 4 denotes an alkyl or alkoxy group having a carbon number of 3 to 16 which is straight-chained or branched, and each of X 5 , X 6 , X 7 , X 8 , X 9 and X 10 denotes a hydrogen or halogen atom, at least one of which denotes a fluorine atom.)

Claim 26

Dependent Claim 18 words

The method of claim 20 in which the frequency of the alternating voltage is more than 10 Hz.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-11-06	1999-05-08	1999-11-07	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-11-06	2003-05-08	2003-11-07	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-11-06	2007-05-08	2007-11-07	$7700.00	Window Closed / Lapsed

Gradation driving method for bistable ferroelectric liquid crystal using effective cone angle in both states

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