Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1998-01-28
2001-03-20
Dudek, James A. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
Reexamination Certificate
active
06204903
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a reflector having new distribution characteristics of reflected light amounts, and a reflective polarizing plate and a reflective liquid crystal display comprising such a reflector.
PRIOR ART
In these years, liquid crystal displays are used in various fields, for example, notebook type word processors, personal computers, electronic pocket data books, portable information terminals, amusement equipment, stationery goods, portable telephones, and the like. In particular, reflective liquid displays or semi-transmissive-reflective liquid displays are widely used for portable equipment.
As the reflective liquid crystal displays, those having the structure of first polarizing plate/liquid crystal cell/second polarizing plate/reflector (twisted nematic (TN) cells and super twisted nematic cells), and those having the structure of liquid crystal cell/reflector (guest-host (GH) cells) are used.
The semi-transmissive-reflective liquid crystal displays are used as reflective displays in the daytime or in the light, while they are used as transmissive displays using a back light at night or in the dark.
As the semi-transmissive-reflective liquid crystal displays, those having the structure of first polarizing plate/liquid crystal cell (a TN or STN cell)/second polarizing plate/semi-transmissive reflector/back light are known.
Since the reflective liquid crystal displays and the semi-transmissive-reflective liquid crystal displays which are used as reflective ones use reflection of external light as a light source, the visibility of their images deteriorate when the images are viewed from an angle at which glares of the images caused by the reflection of external light on the outermost surface, for example, the first polarizing plate, can be avoided.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a reflector which can display bright images with good visibility on a screen of a reflective liquid crystal display, in particular, a portable reflective liquid crystal display, when the reflector is attached on such a liquid crystal display and the image is viewed from an angle at which the reflection of the external light is avoided.
Another object of the present invention is to provide a semi-transmissive reflector which can display bright images with good visibility on an image of a semi-transmissive-reflective liquid crystal display, in particular, a portable semi-transmissive-reflective liquid crystal display, when the reflector is attached on such a liquid crystal display and the image is viewed from an angle at which the reflection of the external light is avoided.
These and other objects and effects of the present invention will be apparent from the following descriptions.
Accordingly, the present invention relates to
a reflector having one or two reflection angles which exhibit maximums in an angle-dependent distribution curve of intensity of reflected light which is generated when light is illuminated from a light source on the surface of the reflector at specific angles,
wherein at least one angle exhibiting said maximum deviates by at least 5 degrees from a regular reflection angle in relation to the incidence angle of the light, and the surface roughness of the reflector is between 200 nm and 1500 nm in terms of a center line average roughness (Ra),
a reflective polarizing plate comprising such a reflector, and
a reflective liquid crystal display comprising such a reflective polarizing plate.
Furthermore, the present invention relates to
a semi-transmissive reflector having one or two reflection angles which exhibit maximums in an angle-dependent distribution curve of intensity of reflected light which is generated when light is illuminated from a light source on the surface of the reflector at specific angles,
wherein at least one angle exhibiting said maximum deviates by at least 5 degrees from a regular reflection angle in relation to the incidence angle of the light,
a semi-transmissive-reflective polarizing plate comprising such a semi-transmissive reflector, and
a semi-transmissive-reflective liquid crystal display comprising such a semi-transmissive-reflective polarizing plate.
REFERENCES:
patent: 4040727 (1977-08-01), Ketchpel
patent: 4298249 (1981-11-01), Gloor et al.
patent: 4431272 (1984-02-01), Yazawa et al.
patent: 4706173 (1987-11-01), Hamada et al.
patent: 5128787 (1992-07-01), Blonder
patent: 62-91918 (1987-04-01), None
patent: 4-274217 (1992-09-01), None
Hayashi Narutoshi
Kurata Nobuyuki
Dudek James A.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Sumitomo Chemical Company Limited
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