Light guide capable of optically changing color of light

Details Light guide capable of optically changing color of light Light guide capable of optically changing color of light

2002-02-04

2004-03-09

Parker, Kenneth (Department: 2871)

Liquid crystal cells, elements and systems

Particular structure

Particular illumination

C349S065000, C349S062000, C362S035000

Reexamination Certificate

active

06704071

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention is related to a photoconductor cell, which not only is able to optically change color of light, but also is able to enhance the brightness of back light of a liquid crystal display.
FIG. 8
shows a conventional photoconductor module
90
applied to liquid crystal display. The photoconductor module
90
includes light-emitting diode (LED) or cold-cathode-ray tube (CCFL) as light source
91
and is used in photoconduction technique of back light. A scattering layer
94
is connected on the light outgoing face
922
of the photoconductor cell
92
. A color-changing layer
93
is laid on the scattering layer
94
. A brightening layer
95
is laid on the color-changing layer
93
. A reflecting layer
96
is laid under the photoconduction face
921
of the photoconductor cell
92
. The reflecting layer
96
and the photoconduction face
921
serve to make the light beam emitted from the point light source or linear light source outgo from the light outgoing face
922
to the liquid crystal module
97
. When reaching the scattering layer
94
, the light beam is evened. Then, the light reaches the color-changing layer
93
to change the color. Accordingly, the liquid crystal module
97
can present back light with predetermined color.
In prior art, the color of the back light of the liquid crystal display without color-changing film is determined by the color of the light emitted from the light source
91
. For example, when it is desired to have blue back light of the liquid crystal display, it is necessary to use a blue light source
91
. When it is desired to have orange back light of the liquid crystal display, it is necessary to use an orange light source
91
. Therefore, in order to have various back light colors, light sources
91
with different colors are generally used in the electronic products. However, the light sources have limited colors. Therefore, for achieving a specific color other than the color of the light source, a color-changing film
93
is necessary to optically change the color.
With respect to the back light of color liquid crystal display, the back light is desired to be white and have better brightness. However, the white light source has higher price so that light sources of blue, green, orange, red, etc. are often selected for lowering the cost. At this time, the color needs to be optically changed into white.
A conventional color-changing film
93
for optically changing the color is only blended with a specific color material to convert the color of back light. However, the color material itself will interrupt and absorb the light so that the light emitted from the light source
91
will be interrupted and the brightness of the back light will be reduced. As a result, the liquid crystal display is darkened and can be hardly clearly seen.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide a light guide capable of optically changing color of light. A brightening layer is disposed on the light guide. The brightening layer includes therein numerous optical particles, which are able to enhance the brightness of the light in perpendicular direction. Therefore, the entire brightness of the display is enhanced.
It is a further object of the present invention to provide the above light guide in which a color-changing layer is disposed on the light guide. The color-changing layer is blended with predetermined color material for changing the color of light into a predetermined color so as to achieve various colors of back light.
The present invention can be best understood through the following description and accompanying drawings wherein:


REFERENCES:
patent: 5866039 (1999-02-01), Morton
patent: 5995288 (1999-11-01), Kashima et al.
patent: 6280063 (2001-08-01), Fong et al.
patent: 2003/0039113 (2003-02-01), Murr et al.

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