Liquid crystal cells – elements and systems – Particular structure – Holder – support – frame – or housing
Reexamination Certificate
2000-02-14
2001-12-11
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Holder, support, frame, or housing
C349S060000
Reexamination Certificate
active
06330045
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to a liquid-crystal display device and more particularly to a liquid-crystal display device with no display variations caused by heat.
2. Background of the Invention
As shown in
FIG. 11
, in a notebook-size personal computer having a narrow frame construction, heat generated from an inverter such as shown in
FIG. 12
directly influences on display quality of the liquid-crystal display panel.
This is because, within an enclosure of a notebook-size personal computer designed with a narrow frame, the inverter and the liquid-crystal display panel are quite close to each other, the distance between them being virtually zero.
In a liquid-crystal display device configured in this manner, there are elements such as reflective sheets, and thin optical system sheets which have a small thermal capacity.
When a Liquid-crystal display device is driven, the heat generated by the inverter heats only a part of the liquid-crystal display panel. For this reason, a difference in thermal expansion speed occurs between a reflective sheet and the chassis, the reflective sheet, having a smaller thermal capacity, expanding to a greater degree and more quickly, so that it strikes the chassis.
For this reason, wrinkles occur in the sheet, leading to an abnormal screen display.
According, it is an object of the present invention, in view of the above-noted problems in the prior art, to provide a solution to these problems, by providing a novel liquid-crystal display device, in which the difference in thermal expansion speed between the liquid-crystal display panel and a reflective sheet provided on the rear surface thereof is made small, thereby reducing the unevenness in the display.
The Japanese Utility Model No. 3001011 discloses liquid-crystal display device. However, this device is different from the present invention in terms of problem to be solved and constitution thereof.
SUMMARY OF THE INVENTION
In order to achieve the above-noted objects, the present invention has the following basic technical constitution.
A first aspect of the present invention is a liquid-crystal display device having a liquid-crystal display panel, a light source provided in proximity to the liquid-crystal display panel for illuminating the liquid-crystal display panel, transformer of the light source provided in proximity to the liquid-crystal display panel, and an enclosure for housing the liquid-crystal display panel, the light source and the transformer, a gasket is provided between the liquid-crystal display panel and the enclosure for controlling a thermal gradient of the liquid-crystal display panel.
In a second aspect of the present invention, the gasket is disposed in proximity to the light source.
In a third aspect of the present invention, the gasket is made of a foam material with resilience and covered with an electrically conductive material.
In a fourth aspect of the present invention, the thermal capacity of the gasket satisfies the following relationship.
Q
4
′
ⅆ
T
4
ⅆ
t
<
C
4
≦
∫
(
Q
2
-
Q
4
+
Q
4
′
)
ⅆ
t
∫
ⅆ
T
4
ⅆ
t
ⅆ
t
where C
4
is the thermal capacity of said enclosure, Q
2
is a heat flow between an air layer in said enclosure and said liquid-crystal display panel, Q
4
is a heat flow between said gasket and said enclosure, Q′
4
is a heat flow between said gasket and an air layer in said enclosure, and T
4
is a temperature of said gasket.
In a liquid-crystal display device configured as noted above, when the inverter is started to drive the liquid-crystal display device, there is a sudden generation of heat from the transformer, this heat being transmitted to the liquid-crystal display panel.
However, because the gasket acts to reduce the speed of the temperature change in the liquid-crystal display panel, the speed of temperature change in a reflective sheet and a chassis also is reduced. For this reason, thermal expansion speed difference between a reflective sheet and a chassis reduces due to differences in thermal capacity, and the reflective sheet does not strike the chassis. Therefore, wrinkling of the reflective sheet is eliminated, and abnormal display is prevented.
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Chowdhury Tarifur R.
Hayes, Soloway, Hennessey Grossman & Hage, P.C.
NEC Corporation
Sikes William L.
LandOfFree
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