The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 21, 1992
Filed:
May. 08, 1989
Kazuo Kawasaki, Hyogo, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A liquid-crystal display apparatus comprising two substrates opposing each other and having electrodes formed on the opposing surfaces, at least one of the electrodes being transparent, a nematic liquid crystal layer interposed between the substrates and having pre-tilt angle .theta. of greater than 1.degree. with respect to the surfaces of the substrates, and having a twisting angle of 180.degree. to 360.degree. from the first substrate to the second substrate, a first polarizer arranged on that side of the first substrate which faces away from the electrode formed thereon, a second polarizer arranged on that side of the second substrate which faces away from the electrode formed thereon, and an optical retardation member or a combination of an optical retardation member and a quarter-wave plate, each located between the polarizers. The value of R=.DELTA.n.multidot.d cos.sup.2 .theta. ranges from 0.4 to 0.8, where .DELTA.n is the optical anisotropy of the nematic liquid crystal material, d (.mu.m) is the thickness of the liquid crystal layer, and .theta. is the pre-tilt angle of the liquid crystal material. The value of R'=.DELTA.n'.multidot.d' ranges from 0.22+0.55 m to 0.42+0.65 m, or from 0.47+0.55 m to 0.67+0.65 m (m=0, 1, or 2), where .DELTA.n' is the optical anisotropy of the optical retardation member and d' (.mu.m) is the thickness of the optical retardation member. Owing to the optical retardation member located between the polarizers, and also to the specific values of R and R', the apparatus can perform high-quality monochrome display with great background whiteness and high image contrast.