Liquid crystal display device

Details Liquid crystal display device Liquid crystal display device

2002-02-27

2003-10-28

Kim, Robert H. (Department: 2871)

Liquid crystal cells, elements and systems

Particular structure

Holder, support, frame, or housing

Reexamination Certificate

active

06639635

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device with high mechanical strength.
2. Description of the Related Art
In general, a liquid crystal display (LCD) device used for a computer such as a portable computer or for a portable display is shown in FIG.
1
. Referring to
FIG. 1
, the LCD device
10
includes a liquid crystal panel
100
, a back light unit
101
, and a driving circuit board
102
. The back light unit
101
is composed of a luminescent lamp
104
, a lamp housing
106
, a light guide
108
, a reflector
110
reflecting the incident light from the horizontal direction to the vertical direction, a protection sheet
112
contacting the light guide
108
, a first prism sheet
114
and a second prism sheet
116
set on the protecting sheet
112
, a diffuser
118
diffusing the light from the first and second prisms
114
and
116
to a viewing area
120
of the liquid crystal panel
100
with a certain viewing angle, and a housing
122
supporting these elements. The liquid crystal display device
10
also comprises a frame
124
coupled to the housing
122
for holding the liquid crystal panel
100
and back light unit
101
.
Referring to
FIG. 2
, the liquid crystal display device
10
is usually combined with, for example, a notebook computer (not shown) as an output screen via a rear case
130
and a front case
134
. The housing
122
of the LCD device
10
is mounted to the rear case
130
and the front case
134
using fastening elements, like screws
132
. The front case
134
has a blank area adjusted to the viewing area.
FIG. 3
a
is a cross-sectional view taken from the line
3
a
—
3
a
of FIG.
2
. As shown, the frame
124
of the LCD device
10
has a plurality of holes
138
defined therein, and the housing
122
has a plurality of projections
136
for snap fitting into the holes
138
of the frame
124
. The projections
136
of the housing
122
are engaged with the holes
138
of the frame
124
such that the housing
122
and the frame
124
are combined with each other.
Typically, as shown in
FIG. 2
, there is no hole formed in the central part
140
of the longer sides
142
of the frame
124
thereby acquiring a higher mechanical strength. Therefore, as shown in
FIG. 3
b
, the central part of the housing
122
(corresponding to the central part
140
of the frame
124
) is flat without any projection provided thereon. However, when the liquid crystal display device
10
is subjected to environment tests, especially the vibration test, stress is generally maximum at the central part
140
of the longer sides
142
of the frame
124
thereby causing unacceptable deformation at the central part
140
Accordingly, there exists a need in the art for a liquid crystal display device which overcomes, or at least reduces the above-mentioned problems of the prior art.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a liquid crystal display device with high mechanical strength, particularly in the central portion of the longer side thereof.
To achieve the above listed and other objects, the present invention provides a liquid crystal display device mainly comprising a liquid crystal panel, a back light unit, a housing and a frame. The liquid crystal panel has opposing upper and lower surfaces. The back light unit is disposed under the lower surface of the liquid crystal panel and joined with it. The housing supports the back light unit and has a wall erected around the back light unit. The frame has a first portion covering at least one edge of the upper surface of the liquid crystal panel and a second portion coupled to the wall of the housing.
According to a first preferred embodiment of the present invention, the housing has at least one projection formed at the wall and the second portion of the frame is pressed by the projection such that the first portion of the frame is curved and concave toward the upper surface of the liquid crystal panel. Preferably, the second portion of the frame is curved and concave to touch the upper surface of the liquid crystal panel. Preferably, the projection is integrally formed with the housing.
According to a second preferred embodiment of the present invention, the second portion of the frame has at least one projection protruded in a direction toward the wall of the housing and the projection of the frame is pressed by the wall of the housing such that the first portion of the frame is curved and concave toward the upper surface of the liquid crystal panel and preferably touches the liquid crystal panel. It is preferred that the projection is integrally formed with the frame. Alternatively, the projection may be formed by press operation applied to the second portion of the frame.
Preferably, the projection is formed in the central part of the longer portion of the wall or the longer side of the second portion of the frame such that the first portion of the frame is curved in the central part of the longer side thereof. This significantly reinforces and stabilizes the structure of the frame and improves the mechanical strength of the frame, particularly in the central portion of the longer side thereof
It is preferred that the projection is chamfered to facilitate assembly of the frame and the housing.

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