Co-ordinate addressing of smectic display cells
First Claim
1. A method of co-ordinate matrix addressing an internally electroded liquid crystal display cell which has a layer of smectic material sandwiched between two electroded plates with a first array of electrodes on one of the plates crossing over a second array on the other plate thereby defining a set of elemental volumes, each individual element being defined by the thickness of the liquid crystal layer and the area of overlap between a member of the first array and a member of the second array, the smectic material being capable of producing dynamic scattering in response to the application of a first electric potential having a first set of predetermined characteristics and of maintaining static focal-conic scattering subsequent to the application and removal of said first potential, said cell being further provided with means for selectively restoring said smectic material in a selected one of said set of elemental volumes to a non-scattering substantially homeotropically aligned state in response to the application of a second electric potential having a second set of predetermined characteristics between the two electrodes defining said selected elemental volume, said method comprising:
- (a) applying said first potential to said set of elemental volumes so as to cause dynamic scattering therein;
(b) removing said first potential to thereby cause said static focal-conic scattering in said set of elemental volumes;
(c) restoring selected ones of said elemental volumes to said non-scattering substantially homeotropically aligned state by sequentially applying said second electrical potential to corresponding ones of said electrodes; and
(d) interrupting step (c) by applying a "blanking" potential having a third predetermined set of characteristics simultaneously to all of said set of elemental volumes to re-initiate dynamic scattering in the unselected ones of said elemental volumes while leaving previously restored ones of elemental volumes in said non-scattering substantially homeotropically aligned state.
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Accused Products
Abstract
A co-ordinate matrix addressing system is used to address a liquid crystal display cell containing a positive dielectric anisotropy smectic material. For this purpose one or more direct voltage pulses are applied across selected elemental volumes of the display to convert them from a focal-conic scattering state to a homeotropically aligned state. Prior to this all elements are electrically driven into the turbulent scattering state which relaxes into the focal-conic scattering state upon removal of the driving field. The driving field may also take the form of direct voltage pulses. Unselected elemental volumes may be refreshed to substantially their original level of focal-conic scattering by means of a suitable blanking potential applied to both selected and unselected elemental volumes which nevertheless leaves previously restored elemental volumes in the homeotropically aligned state.
18 Citations
12 Claims
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1. A method of co-ordinate matrix addressing an internally electroded liquid crystal display cell which has a layer of smectic material sandwiched between two electroded plates with a first array of electrodes on one of the plates crossing over a second array on the other plate thereby defining a set of elemental volumes, each individual element being defined by the thickness of the liquid crystal layer and the area of overlap between a member of the first array and a member of the second array, the smectic material being capable of producing dynamic scattering in response to the application of a first electric potential having a first set of predetermined characteristics and of maintaining static focal-conic scattering subsequent to the application and removal of said first potential, said cell being further provided with means for selectively restoring said smectic material in a selected one of said set of elemental volumes to a non-scattering substantially homeotropically aligned state in response to the application of a second electric potential having a second set of predetermined characteristics between the two electrodes defining said selected elemental volume, said method comprising:
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(a) applying said first potential to said set of elemental volumes so as to cause dynamic scattering therein; (b) removing said first potential to thereby cause said static focal-conic scattering in said set of elemental volumes; (c) restoring selected ones of said elemental volumes to said non-scattering substantially homeotropically aligned state by sequentially applying said second electrical potential to corresponding ones of said electrodes; and (d) interrupting step (c) by applying a "blanking" potential having a third predetermined set of characteristics simultaneously to all of said set of elemental volumes to re-initiate dynamic scattering in the unselected ones of said elemental volumes while leaving previously restored ones of elemental volumes in said non-scattering substantially homeotropically aligned state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification