Stock material or miscellaneous articles – Structurally defined web or sheet – Including variation in thickness
Reexamination Certificate
1999-06-18
2001-08-21
Loney, Donald J. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including variation in thickness
C428S167000, C428S913000, C359S321000, C359S454000
Reexamination Certificate
active
06277471
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a brightness enhancement film, and more particularly, relates to the brightness used in a backlit liquid crystal display.
2. Description of the Related Art
A backlit liquid crystal display generally includes a brightness enhancement film which is typically positioned between a diffuser and a liquid crystal display panel. The backlit liquid crystal display also includes a light source such as a fluorescent lamp, a light guide for transporting light for reflection toward the liquid crystal display panel, and white reflector for reflecting light toward the liquid crystal display panel. The brightness enhancement film collimates light emitted from the light guide thereby increasing the brightness of the liquid crystal display panel. The increased brightness enables a sharper image to be produced by the liquid crystal display panel and allows the power of the light source to be reduced to produce a selected brightness. The brightness enhancement film in the backlit liquid crystal display is useful in equipment such as computers, personal TVs, video recorders, mobile communication devices, and automobile and avionics instrument displays.
As shown in
FIG. 1
, International Publication No. WO96/23649, public on Aug. 8, 1996, discloses prevention of groove tip deformation in brightness enhancement film. A brightness enhancement film includes a base
101
having a first surface on which prisms
102
are formed by molding and a second surface that is substantially flat or planar and opposite the first surface. After molding, the brightness enhancement film
100
is cured so that it forms the prisms
102
. This is followed by heat treating the prisms
102
. Heat treating is performed at a temperature that is at least equal to a normal glass transition temperature of resin. Heat treating raises the glass transition temperature of the resulting polymer above approximately 333 K such that groove tip impression is reduced. The prisms
102
consist of a first facet
103
and a second facet
104
which are substantially flat or planar. A side-by-side arrangement of regular prisms
102
is preferred for optical performance in one direction because the facets of the prisms
102
refract in a single direction and can concentrate the light from the diffuser. However, one major drawback of WO96/23649 is that the prisms do not refract in two dimensions.
The present invention intends to provide a brightness enhancement film with prisms consisting of a brightness unit preferred for optical performance in two dimensions in such a way as to mitigate the above problem.
SUMMARY OF THE INVENTION
The primary objective of this invention is to provide a brightness enhancement film which includes prisms containing a plurality of brightness units preferred for optical performance in two dimensions.
The present invention is a brightness enhancement film. A brightness enhancement film essentially comprises a base and a brightness layer. A brightness layer is molded to create a plurality of prisms in molding process. And the brightness layer is adhesively attached to the top surface of the base before the curing process so as to form the brightness enhancement film. Therefore, the top surface of the brightness layer and the bottom surface of the base together define the top surface and the bottom surface of the brightness enhancement film. Light from the diffuser penetrates the base from the bottom surface to the top surface. After that light further penetrates the bottom surface of the brightness layer and is to be refracted by the top surface of the brightness layer thereby enhancing for optical performance in two dimensions.
Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description and the accompanying drawings.
REFERENCES:
patent: 5229882 (1993-07-01), Rowland
patent: 5300263 (1994-04-01), Hoopman et al.
patent: 5462700 (1995-10-01), Beeson et al.
patent: 5831766 (1998-11-01), Martin et al.
patent: 6178224 (2001-01-01), Polichar et al.
patent: WO 96/23649 (1996-08-01), None
Bacon & Thomas
Loney Donald J.
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