Liquid crystal cells – elements and systems – Particular structure – Holder – support – frame – or housing
Reexamination Certificate
1999-06-07
2002-04-16
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Holder, support, frame, or housing
C361S689000
Reexamination Certificate
active
06373537
ABSTRACT:
This application claims the benefit of Korean Application No. 12899/1997 filed on Apr. 8, 1997, and Korean Application No. 14278/1997 filed on Apr. 17, 1997, which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a computer, and more particularly, to a liquid crystal display unit of a portable computer.
2. Discussion 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 includes a liquid crystal panel
20
, a back light unit
22
, and a driving circuit board
23
. The back light unit
22
is comprised of a luminescent lamp
11
, a lamp housing
12
having a U-shape cross section and surrounding the lamp
11
, a light guide
13
, a reflector
14
reflecting the incident light from the horizontal direction to the vertical direction, a protection sheet
15
contacting the light guide
13
, a first prism sheet
16
and a second prism sheet
17
set on the protecting sheet diffuser
15
and directing the incident light from the light guide
13
to specific direction, a diffuser
18
diffusing the light from the first and second prisms
16
and
17
to a viewing area
21
of the liquid crystal panel
20
with a certain viewing angle, and a first support frame
19
supporting these elements of the LCD device.
FIG. 2
shows a cross-sectional view of the light-guiding plate
13
showing a gradual decrease in thickness as the light guiding plate
13
extends away from the light source
11
. A fluorescent lamp
11
as the light source is fixed at the thicker end of the light-guiding plate
13
. When the fluorescent lamp
11
is turned on, the light
23
from the source
11
is reflected by the lamp housing
12
surrounding the fluorescent lamp
11
. The reflected light transmits through the light guiding plate
13
towards the other side (thinner end) of the light-guiding plate
13
as indicated by the arrows. Then, the light spreads all over the surface of the light-guiding plate
13
and reaches the display area
21
(
FIG. 1
) through the diffusion plate
18
. At the same time, a thin film transistor formed on the liquid crystal panel controls a corresponding pixel according to the signals from the driving circuit
23
(
FIG. 1
) to selectively transmit the light in that pixel. The same process in each pixel collecting produce the display of images on the display area
21
.
The liquid crystal display is usually combined with, for example, a notebook computer for use as an output screen. The following method is used to attach the liquid crystal display to a device such as a notebook computer.
Referring to
FIGS. 3
a
and
3
b
, in a conventional liquid crystal display, a ground supporting plate
30
is disposed on the first fastening frame
19
. A mounting hole
33
is formed through the ground supporting plate
30
and the first fastening frame
19
, as shown in
FIG. 3
b
. Then, the ground supporting plate
30
and the first fastening frame
19
are fixed by a screw
31
as shown in
FIG. 3
a
. In other words, a liquid crystal display is attached to a device such as a notebook computer in a manner so as to fasten the first fastening frame
19
and the ground supporting plate
30
by a fastening element such as a screw.
However, the liquid crystal display is necessarily made thicker due to the length of the screw according to the method as shown in
FIGS. 3
a
and
3
b
. Moreover, since the mounting hole
33
for the screw is formed on the front surface of the liquid crystal display, the display area of the liquid crystal display must necessarily be narrowed to permit sufficient space at the margin of the front surface to accommodate mounting hole
33
and screw
31
.
According to the structure described above, the LCD device operates as follows. The light from the luminescent lamp
11
is incident on the rear surface of the liquid crystal panel
20
through the back light unit
22
. A control circuit placed on the driving circuit board
23
controls the incident light on the viewing area
21
of the liquid crystal panel
20
to display images and characters.
FIG. 4
is a drawing showing a plan view of the final assembly structure of the conventional liquid crystal display device.
FIG. 4
also shows the assembled result of a second support frame
40
, liquid crystal panel
20
and back light unit having an assembly structure for mounting to a portable computer. The second support frame
40
is made of metal or plastic, and holds the liquid crystal panel
20
and the back light unit. Here, the driving circuit board
23
is located behind the rear part of the back light unit connected to the liquid crystal panel
20
with a flexible film (not shown).
FIG. 5
shows the assembly structure of the liquid crystal panel
20
and body
60
of the portable computer in the conventional method. The second support frame
40
is mounted to a rear case
50
of the portable computer using screws
43
through screw holes
41
. A front case(not shown) having a blank area adjusted to the viewing area is joined at the rear case
50
. That is, the liquid crystal panel
20
is attached to the rear case
50
by the screws
43
through the screw holes the display surface in the normal direction of the surface
41
formed on. Although not shown in the drawings, the front case is mounted on the LCD device, opening the viewing area
21
and covering the other parts.
In general, as the size of the portable computer is designed for easy movement, the ratio of the viewing area to the whole surface area of the display and the thickness of the display device affects the quality of the portable computer. However, in a conventional portable computer, screw holes
41
are located on edge portions of the display surface in order to join the second support frame
40
to the rear case
50
. As the display area has a screw frame area
42
(
FIG. 4
) for forming the holes
41
, the ratio of the area of the LCD panel to the viewing area
21
is reduced.
Furthermore, in the conventional portable computer, as the screws
43
are mounted in the liquid crystal display device and the rear case
50
in the normal direction of the display surface, the display part is necessarily thick enough to form an assembly device
51
for the screws
43
, such as screw holes
41
. The second support frame
40
is also necessarily large enough to have a space for supporting the screw holes
41
. Thus, it is difficult to reduce the weight of the portable computer.
Accordingly, a liquid crystal device is needed having a high viewing ratio of the display, low weight, and reduced thickness for a computer, such as a portable computer.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a computer that substantially obviates one or more of the problems due to limitations and disadvantages of the related art while retaining the advantages.
An object of the present invention is to increase the ratio of the viewing area to the whole area of a computer display.
Another object of the present invention is to provide a thin, lightweight display unit.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a liquid crystal display device comprises a liquid crystal panel including a back light unit including a light source joined with the liquid crystal panel; a first frame coupled to a surface of the backlight unit and to the sides of the liquid crystal panel; a second frame coupled to the edges of the liquid crystal panel and to the side
Bang Young Un
Kim Yong Bum
Lee Byeong Yun
Moon Kyo Hun
Yun Hee Young
LG. Philips LCD Co. Ltd.
Long Aldridge & Norman LLP
Ton Toan
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