Liquid crystal cells – elements and systems – Particular structure – Particular illumination
Reexamination Certificate
2001-02-22
2003-06-17
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Particular illumination
C362S035000
Reexamination Certificate
active
06580478
ABSTRACT:
This application claims the benefit of Korean Patent Application No. 2000-9176, filed on Feb. 24, 2000, which is hereby incorporated by reference for all purposes as if filly set forth herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a structure of a liquid crystal display module having a supporting frame in a backlight device.
2. Discussion of the Related Art
Liquid crystal displays (LCDs) are gaining in popularity for use in systems such as television receivers, computer monitors, avionics displays, aerospace displays, and other military-related displays where the elimination of cathode ray tube (CRT) technology is desirable for several reasons. In particular, CRTs are characterized by large depth dimensions, undesirably high weight, and fragility. Additionally, CRTs require a relatively high voltage power supply in order to sufficiently accelerate electron beams for displaying images.
The aforementioned shortcomings of CRTs are overcome by flat panel liquid crystal displays in which matrix arrays of liquid crystal picture elements or pixels are arranged in a plurality of rows and columns. In general, LCD devices have various advantages in that they are thin, and consume little power, and so on, in comparison with CRT display devices. Therefore, such LCD devices might be expected to be substituted for CRT display devices and have been a matter of great interest in some industry fields.
In contrast to the CRT, the liquid crystal display device requires a light source because the liquid crystal is not fluorescent material. Therefore, as the light source lamp, a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL) or the like is used. Moreover, there are a few kinds of backlight units such as a direct backlight type (or direct type) unit and an edge light type unit.
A direct backlight type surface light source device generally reflects light from a light source onto the back surface of a liquid crystal panel or the like by means of a reflective plate, and diffuses its output light by means of a light diffusing sheet disposed at the light outputting surface side so that the shape of the light source cannot be identified by human eyes. An edge light type surface light source device receives light inputted into it from a light source usually through one side end surface of a plate-shaped light guide means of a transparent acryl resin or the like. The edge light type surface light source device leads the light to a light outputting surface which is the other surface of the light guide means, and therefrom outputs the light to the back surface of a liquid crystal panel or the like. In such a case, in order to improve the efficiency of utilizing light, an optical reflective plate or an optical reflective film is often provided on the opposite surface of the light guide means to the light outputting surface and in order to make the output light uniform, a light diffusing sheet having a light diffusing function is often provided at the light outputting surface side of the light guide means.
The reference is explained hereinafter referring to the edge light type surface light source device.
FIG. 1
is a plan view illustrating a large general LCD module, and
FIG. 2
is a cross-sectional view taken along line II—II of FIG.
1
. As shown in
FIGS. 1 and 2
, the LCD module
10
generally includes: a liquid crystal (LC) panel
20
comprising two substrates and an interposed liquid crystal layer; a panel guide
30
guiding the LC panel
20
; a TCP (Tape Carrier Package)
28
including integrated circuit (IC) chips
26
; a PCB (Printed Circuit Board)
32
connected to the pad of the LC panel
20
through the TCP (Tape Carrier Package)
28
; a backlight device
40
positioned under the LC panel
20
; a top frame
70
supporting the LC panel
20
, and a supporting frame
80
. The top frame
70
is made of metallic material, and the supporting frame
80
is made of molded plastic.
The supporting frame
80
holds the liquid crystal display device and houses a reflective sheet
42
, a light guide plate
44
, a light diffusing sheet
46
, a prism sheet
48
and a protection sheet
50
. The fluorescent lamp with a diameter of a few millimeters is installed at one or both ends of the light guide plate
44
. The light guide plate
44
serves to uniformly direct light from the lamp to the LC panel
20
, and it is usually made of a transparent acryl having a thickness of a few millimeters. The light guide plate
44
also has a plurality of convex or concave hole dots or a plurality of V-shaped convex or concave bars in order to uniformly reflect and diffuse the light. The reflective sheet
42
is arranged under the light guide plate
44
and upwardly reflects the light from the light guide plate
44
. The prism sheet
48
and light diffusing sheet
46
over the light guide plate
44
can be two or three sheets. The prism sheet
48
and the light diffusing sheet
46
gather or diffuse the light in order to improve the brightness and to increase the range of vision. The protection sheet
50
protects the sheets from particles and from scratches. The protection sheet
50
also prevents the sheets from swinging when conveying the backlight device assembly.
In the LCD module
10
described above, a process of aligning the backlight device
40
to the supporting frame
80
will be explained hereinafter. First, the lamp is installed alongside the supporting frame
80
. After that, the reflective sheet
42
, which is made of polyester, is assembled in order to reflect the light upward. The light guide plate
44
is then assembled over the reflective sheet
42
in order to uniformly reflect the light irradiated from the lamp. The light diffusing sheet
46
, which diffuses the light, and the prism sheet
48
, which gathers the light, are assembled. Then, the light guide plate
44
and the sheets are fastened by the tapes, by the air pad, and by the protrusion of the supporting frame
80
.
Meanwhile, the number of lamps is increased in the conventional art in order to improve the brightness of the large LCD device, and thus the power consumption increases. However, some problems occur in the LCD device because of the heat from the lamp and from the PCB
32
. Thus, in order to solve the problems caused by the heat, the supporting frame
80
is made of the metallic material such as aluminum (Al) that has a good thermal conductivity and a good thermal radiation. And then, the supporting frame
80
is installed in the bottom side of the lamp housing and in the vertical side portion of the lamp housing. Moreover, a heat emitting plate (not shown) is connected to the lamp housing of the backlight device
40
as a means of emitting heat such that heat is emitted from the LCD device.
However, the reflective sheet
42
directly contacting the supporting frame
80
is badly affected by the internal heat from the lamp and PCB
32
and by the external heat occurring in operation and maintenance tests at high temperature, because the internal and external heat is emitted from the supporting frame
80
that is made of metallic material. Especially, wrinkles occur in the reflective sheet
42
, and thus there are stains in the display area in an operating mode. Therefore, deterioration of the LCD device arises.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a structure of preventing wrinkle in a reflective sheet of backlight unit that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an LCD module with a structure that can prevent the reflective sheet from wrinkling.
Another object of the invention is to provide an LCD module that improves picture quality and display characteristics.
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
LG. Philips LCD Co., Ltd
McKenna Long & Aldridge LLP
Ton Toan
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