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US 2003/0076455 A1Published application
Optically optimized permanently bistable twisted nematic liquid crystal displays
AssigneeThe Hong Kong University of Science and Technology
InventorsHoi-Sing Kwok, Jian-Xin Guo
Life of this patent
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Abstract
The structure and construction of a bistable twisted nematic liquid crystal display with very long lifetime are disclosed. The two stable twist states in this display when no voltage is applied have almost infinite lifetimes and do not decay. These two stable twist states differ by a twist angle of 180°. New design conditions of this bistable twist structure are disclosed such that the contrast and the brightness are both optimized. This display can be operated in transmittive mode with two polarizes or in the reflective mode with one polarizer.
Claims20
A liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±22±5°;
- b) an input polarizer with an angle of ±45±5° and an output polarizer at an angle of ±68±5°;
- c) a chiral dopant added to the liquid crystal such that ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.19±0.1
- d) the thickness times the birefringence of the liquid cell being 0.27±0.1 μm.
1 more element
A liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±22±5°;
- b) an input polarize with an angle of ±45±5° and an output polarizer at an angle of ±68±5°;
- c) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.31±0.15
- d) the thickness times the birefringence of the liquid cell being 0.55±0.15 μm.
1 more element
A liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±68±5°;
- b) an input polarizer with an angle of ±45±5° and an output polarizer at an angle of ±23±5°;
- c) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.38±0.2
- d) the thickness times the birefringence of the liquid cell being 0.80±0.2 μm.
1 more element
A liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of 112±5°;
- b) an input polarizer with an angle of ±45±5° and an output polarizer at an angle of 23±5°;
- c) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.56±0.3
- d) the thickness times the birefringence of the liquid cell being 1.05±0.2 μm.
1 more element
A liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±158±5°;
- b) an input polarizer with an angle of ±45±5° and an output polarizer at an angle of ±68±5°;
- c) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.69±0.3
- d) the thickness times the birefringence of the liquid cell being 1.3±0.3 μm.
1 more element
A single polarizer reflective liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±174±5°;
- b) an input polarizer with an angle of ±41±5°;
- c) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.47±0.3
- d) the thickness times the birefringence of the liquid cell being 0.14±0.2 μm.
1 more element
A single polarizer reflective liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±133±5°;
- b) an input polarizer with an angle of ±32±5°;
- c) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.24±0.3
- d) the thickness times the birefringence of the liquid cell being 0.14±0.2 μm.
1 more element
A single polarizer reflective liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±174±5°;
- b) an input polarizer with an angle of ±13±5°;
- c) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.47±0.3
- d) the thickness times the birefringence of the liquid cell being 0.55±0.2 μm.
1 more element
A single polarizer reflective liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±294±5°;
- b) an input polarizer with an angle of ±27±5°;
- e) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.50±0.3
- d) the thickness times the birefringence of the liquid cell being 0.6±0.2 μm.
1 more element
A single polarizer reflective liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±107±5°;
- b) an input polarizer with an angle of ±17±5°;
- c) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.50±0.3
- d) the thickness times the birefringence of the liquid cell being 0.27±0.2 μm.
1 more element
A single polarizer reflective liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±220±5°;
- b) an input polarizer with an angle of ±35±5°;
- c) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.50±0.3
- d) the thickness times the birefringence of the liquid cell being 0.38±0.2 μm.
1 more element
A single polarizer reflective liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±191±5°;
- b) an input polarizer with an angle of ±0.4±5°;
- c) a chiral dopant added to the liquid crystal such that the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.50±0.3
- d) the thickness times the birefringence of the liquid cell being 0.6±0.2 μm.
1 more element
A single polarizer reflective liquid crystal display comprising
- a) liquid crystal cell with rubbing directions of the top and bottom alignment layers that favor a twist angle of ±143±5°;
- b) an input polarizer with an angle of ±40±5°;
- c) a chiral dopant added to the liquid crystal such the ratio of the thickness of the cell and the pitch of the liquid crystal twist is between 0.50±0.3
- d) the thickness times the birefringence of the liquid cell being 0.7±0.2 μm.
1 more element
Dependencies are inferred from the claim text.