Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1997-08-19
1999-03-16
Lipman, Bernard
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524 97, 524106, 524110, 524 94, 524186, 524533, 524535, 524560, 524561, 524310, 524312, 524313, C08K 534
Patent
active
058831630
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a light conducting plate for surface lighting having an improved luminance and an improved tone which can be used for back lighting of liquid crystal displays, etc. used in office automation equipment, such as word processors or personal computers, or various monitors of image signals.
BACKGROUND ART
Methacrylic resins are excellent in transparency, weatherability and scratch resistance and are widely used particularly for their transparency as molding materials for optical parts which demand precise molding, such as optical disks and lenses, or for lighting.
The methacrylic resin has recently found use as light conducting plate for back lighting in liquid crystal displays, etc., and the severity of requirements for transparency, color tone and freedom from foreign matter has been increasing. A light conducting plate as herein referred to is a part constituting a side-lighted type surface lighting unit mainly used for back lighting of liquid crystal displays. The side-lighted type surface lighting unit is disclosed in JP-A-57-128383 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). As shown in FIG. 1, the lighting unit of this type comprises a light source, such as a cold cathode gas discharge tube, a hot cathode gas discharge tube, a light bulb or an LED, placed at the side of a light-emitting surface. The light emitted from the light source enters the light conducting plate from the side, changes its direction by a light scattering means provided on the light-reflecting surface, and comes out through a diffusing film via a polarizer to a viewer side. The light scattering strength of the light conducting plate can be designed appropriately in conformity with the distance from the light source or the position of the reflecting surface so as to provide a uniform surface lighting unit. Because such a side-lighted type surface lighting unit has its light source provided at the side of the light conducting plate thereby to contribute to reduction in thickness and weight of the whole display, it has been recently used as a backlight of liquid crystal displays used in laptop or notebook word processors or personal computers. Since such portable equipment is demanded to work for a long period of time with batteries contained therein, the side-lighted type surface lighting unit used for back lighting is required to have a low power consumption.
In FIG. 1 is shown a schematic illustration of a side-lighted type surface lighting unit used as a backlight of a liquid crystal display. Liquid crystal panel 1 possesses a function of controlling a light transmission at a desired position on the screen thereby forming letter or image information. Since liquid crystal panel 1 per se does not emit light, a backlight 2 is needed for obtaining a clear image. As light source 25, a cold cathode fluorescent tube which consumes relatively low power of electricity and yet provides sufficient brightness is of frequent use.
Light conducting plate 21 is a transparent resin plate having provided light-scattering means 22 on the light-reflecting surface thereof. Light-scattering means 22 is formed by injection molding using a mold having a prescribed pattern or by applying a white ink to the light-reflecting side with gradation by, for example, printing. Light conducting plate 21 can have a flat shape as with the case of FIG. 1, a wedge shape having a thickness decreasing with the distance from the light source, and other special irregular shapes. Numeral 23 is a reflecting film which functions to reflect light having passed through light conducting plate 21 to a viewer side thereby to improve light utilization. Numeral 24 is a frosted glass-like cloudy film called a diffusing film. Since light-scattering means 22 has a dot or stripe pattern, diffusing film 24 is effective to prevent such a pattern from being seen through liquid crystal panel 1. At the same time, a surface lighting unit which scatters light uniformly can be obtained by blurring the
REFERENCES:
patent: 4059916 (1977-11-01), Tachihara et al.
patent: 4228267 (1980-10-01), Higashizume et al.
patent: 4246382 (1981-01-01), Honda et al.
patent: 4384097 (1983-05-01), Wingler et al.
patent: 4820757 (1989-04-01), Spang et al.
patent: 4937709 (1990-06-01), Yanagi et al.
patent: 4998809 (1991-03-01), Tsuji et al.
patent: 5040098 (1991-08-01), Tanaka et al.
patent: 5074675 (1991-12-01), Osgood
patent: 5134549 (1992-07-01), Yokoyama
patent: 5622547 (1997-04-01), Maslowski et al.
patent: 5637632 (1997-06-01), Nozaki
Asahi Kasei Kogyo Kabushiki Kaisha
Lipman Bernard
Sarofin N.
LandOfFree
Light conducting resin plate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Light conducting resin plate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Light conducting resin plate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-818330