Liquid crystal display with compensators having minimum retardations in the inclined direction
AssigneeFuji Photo Film Co., Ltd.
InventorsHiroyuki Mori, Yoji Ito
Life of this patent
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Abstract
A liquid crystal display has a bend orientation cell or HAN mode cell and further is provided with an optical compensatory sheet. The optical compensatory sheet shows the minimum of absolute values of retardation values in a direction inclined from the normal of the sheet.
Claims12
A liquid crystal display comprising a liquid crystal cell which comprises a pair of substrates each of which is provided with a transparent electrode having an orientation layer thereon and a layer of nematic liquid crystal sealed therebetween, two polarizing sheets arranged on each side of the cell, and two optical compensatory sheets arranged between the liquid crystal cell and the polarizing sheets, the layer of nematic liquid crystal showing a bend orientation, the nematic liquid crystal varying its angle of director to the plane of the substance under variation of voltage applied to the liquid crystal cell;
- wherein each of the optical compensatory sheets shows the minimum of absolute values of retardation values in a direction inclined from the normal of the sheet, and
- wherein the two optical compensatory sheets satisfy the condition:
- 0.2.times.Re.sub.2 .ltoreq.Re.sub.1 .ltoreq.2.0.times.Re.sub.2
- wherein Re.sub.1 represents an absolute value of a sum of retardation values of the two optical compensatory sheets, and Re.sub.2 represents an absolute value of a retardation value of the layer of nematic liquid crystal of the liquid crystal cell;
- the retardation value of optical compensatory sheet being defined by the formula:
- {(n.sub.2 +n.sub.3)/2-n.sub.1 }.times.d
- in which n.sub.1, n.sub.2 and n.sub.3 are refractive indices in the three axis directions of the optical compensatory sheet n.sub.1, n.sub.2 and n.sub.3 satisfy the condition of n.sub.1 .ltoreq.n.sub.2 .ltoreq.n.sub.3, and d is the thickness in terms of nm of the optical compensatory sheet;
- the retardation value of the layer of nematic liquid crystal being defined by the formula:
- {n.sub.3 -(n.sub.1 +n.sub.2)/2}.times.d
- in which n.sub.1, n.sub.2 and n.sub.3 are refractive indices in the three axis directions of the layer of nematic liquid crystal, n.sub.1, n.sub.2 and n.sub.3 satisfy the condition of n.sub.1 .ltoreq.n.sub.2 .ltoreq.n.sub.3, and d is the thickness in terms of nm of the layer of nematic liquid crystal.
A liquid crystal display comprising a liquid crystal cell which comprises a pair of substrates each of which is provided with a transparent electrode having an orientation layer thereon and a layer of nematic liquid crystal sealed therebetween, the orientation layer of one of the substrates being a layer capable of giving homeotropic structure to the nematic liquid crystal, a polarizing sheet arranged on one side of the cell, the other side of the cell being provided with a reflective plate, and an optical compensatory sheet provided between the liquid crystal cell and the polarizing sheet, the layer of nematic liquid crystal showing hybrid alignment, the nematic liquid crystal varying its angle of director to the plane of the substrate under variation of voltage applied to the liquid crystal cell;
- wherein the optical compensatory sheet shows the minimum of absolute values of retardation values in a direction inclined from the normal of the sheet, and
- wherein the optical compensatory sheet further satisfies the condition:
- 0.2.times.Re.sub.2 .ltoreq.Re.sub.1 .ltoreq.2.0.times.Re.sub.2
- wherein Re.sub.1 represents an absolute value of a retardation value of the optical compensatory sheet, and Re.sub.2 represents an absolute value of a retardation value of the layer of nematic liquid crystal of the liquid crystal cell;
- the retardation value of optical compensatory sheet being defined by the formula:
- {(n.sub.2 +n.sub.3)/2-n.sub.1 }.times.d
- in which n.sub.1, n.sub.2 and n.sub.3 are refractive indices in the three axis directions of the optical compensatory sheet, n.sub.1, n.sub.2 and n.sub.3 satisfy the condition of n.sub.1 .ltoreq.n.sub.2 .ltoreq.n.sub.3, and d is the thickness in terms of nm of the optical compensatory sheet;
- the retardation value of the layer of nematic liquid crystal being defined by the formula:
- {n.sub.3 -(n.sub.1 +n.sub.2)/2}.times.d
- in which n.sub.1, n.sub.2 and n.sub.3 are refractive indices in the three axis directions of the layer of nematic liquid crystal, n.sub.1, n.sub.2 and n.sub.3 satisfy the condition of n.sub.1 .ltoreq.n.sub.2 .ltoreq.n.sub.3, and d is the thickness in terms of nm of the layer of nematic liquid crystal.
Dependencies are inferred from the claim text.