US4601543A
Expired / Lapsed
US
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Nematic liquid crystal storage display device
Assignee: Nokia Bell Labs
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Filing: 1985-10-17
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Granted: 1986-07-22
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Expires: 2005-10-17
Abstract
Abstract A bistable nematic liquid crystal display cell is switched between topologically equivalent, asymmetric horizontal states. Switching is initiated by application of a directional, symmetry breaking field such as a transverse magnetic field. An electric potential is then applied across the cell to complete the switching cycle and maintain the state. The cell includes upper and lower parallel substrates, upper and lower topographically textured tilt alignment surfaces on the corresponding substrates, and nematic liquid crystal material between the substrates. In an active region of the cell, the tilt alignment surfaces form an equal reverse tilt boundary condition. In an isolation region surrounding the active region of the cell, the tilt alignment surfaces form a parallel tilt boundary condition.
Inventors
- 👤 Gary D. Boyd
- 👤 Julian Cheng
- 👤 Robert B. Meyer
- 👤 Robert N. Thurston
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:26
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/139; G02F1/1391; G02F1/13768; G02F1/132
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
172 words
A liquid crystal display cell capable of being switched to either a first state or a second state, switching between said first state and said second state being in the absence of movement of a disclination in said display cell, the cell comprising first and second substrates disposed in parallel relationship to each other, each substrate having a topographically textured inner surface exhibiting a uniform tilt at an acute surface tilt angle from a respective surface normal, and a nematic liquid crystal material having orientational directors disposed between both substrates, the cell comprising means for initiating a first change in orientational director configuration by breaking symmetry of the liquid crystal display cell to favor the orientational director configuration wherein an inversion layer of orientational directors is substantially adjacent and parallel to the first substrate, and means connected to each substrate for generating an electric potential through the liquid crystal material to complete and maintain the first change in orientational director configuration so that the orientational directors are configured in the first state.
Claim 2
Dependent Claim
172 words
A liquid crystal display cell capable of being switched to either a first state or a second state, switching between said first state and said second state being in the absence of movement of a disclination in said display cell, the cell comprising first and second substrates disposed in parallel relationship to each other, each substrate having a topographically textured inner surface exhibiting a uniform tilt at an acute surface tilt angle from a respective surface normal, and a nematic liquid crystal material having orientational directors disposed between both substrates, the cell comprising means for initiating a first change in orientational director configuration by breaking symmetry of the liquid crystal display cell to favor the orientational director configuration wherein an inversion layer of orientational directors is substantially adjacent and parallel to the first substrate, and means connected to each substrate for generating an electric potential through the liquid crystal material to complete and maintain the first change in orientational director configuration so that the orientational directors are configured in the first state.
Claim 3
Dependent Claim
60 words
The display cell as defined in claim 1 wherein the surface tilt angle for the topographically textured inner surface on the first substrate is substantially equal to, and of opposite polarity to, the surface tilt angle for the topographically textured inner surface on the second substrate so that both topographically textured inner surfaces form an equal reverse tilt boundary condition.
Claim 4
Dependent Claim
70 words
The display cell as defined in claim 2 wherein each topographically textured inner surface has an azimuthal bias with respect to a predetermined reference line, the topographically textured inner surface on the first substrate having an azimuthal bias angle which is in the range of from -90 degrees to +90 degrees, exclusively, and the topographically textured inner surface on the second substrate having an azimuthal bias angle of 0 degrees.
Claim 5
Dependent Claim
104 words
The display cell as defined in claim 3 wherein the means for initiating the first change includes means for initiating a second change in orientational director configuration by breaking symmetry of the liquid crystal display cell to favor the orientational configuration wherein an inversion layer of orientational directors is substantially adjacent and parallel to the second substrate, and the means for generating an electric potential further includes means connected to each substrate for generating an electric potential through the liquid crystal material to complete and maintain the second change in orientational director configuration so that the orientational directors are configured in the second state.
Claim 6
Dependent Claim
68 words
The display cell as defined in claim 4 wherein the means for initiating the first change is comprised of means for generating a static, homogeneous magnetic field through the liquid crystal material and means for adjusting the position of the magnetic field and the first substrate relative to each other so that the magnetic field is oriented in a first predetermined direction with respect to the first substrate.
Claim 7
Dependent Claim
68 words
The display cell as defined in claim 5 wherein the means for initiating the second change is comprised of means for generating a static, homogeneous magnetic field through the liquid crystal material and means for adjusting the position of the magnetic field and the first substrate relative to each other so that the magnetic field is oriented in a second predetermined direction with respect to the first substrate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-07-21 | 1990-01-20 | 1990-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-07-21 | 1994-01-20 | 1994-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-07-21 | 1998-01-20 | 1998-07-22 | $7700.00 | Window Closed / Lapsed |