Illumination – Revolving
Reexamination Certificate
2002-12-27
2004-11-02
Tso, Laura K. (Department: 2875)
Illumination
Revolving
C362S027000
Reexamination Certificate
active
06811276
ABSTRACT:
This application claims the benefit of the Korean Application No. P2002-18269 filed on Apr. 3, 2002, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a backlight device, and more particularly, to a backlight device in a liquid crystal display device.
2. Discussion of the Related Art
Generally, a CRT (cathode ray tube) as one of the display devices as widely used is mainly applied as a monitor for a TV, a measuring device, an information terminal, or the like. However, the weight and size of CRT devices fail to cope with the demand for compact and light electronic devices.
As substitutions for such CRT's, there can be mentioned a liquid crystal display (LCD) using the optical effect of an electrical field, a plasma display panel (PDP) using a gas electrical discharge, an electroluminescent display (ELD) using electroluminescence, and the like.
Thus, substantial effort has been made to study and develop the liquid crystal display device.
Lately, a flat liquid crystal display device having a display screen just several centimeters thick has been developed to be used as a monitor for space craft, for an airplane, as a notebook computer, a lap-top computer, a desk-top computer, a large-sized information display, or the like. Thus, demands for the liquid crystal display device continuously increase.
The liquid crystal display device is a light-receiving device displaying an image by controlling the quantity of light, thereby requiring an additional light source, i.e. a backlight device necessary for applying light to an LCD panel.
Backlight devices currently used include an EL (electroluminescent) backlight device, an LED backlight device, a CCFL (cold cathode fluorescent lamp) backlight device, and the like. The CCFL backlight device has less power consumption, provides a very bright white light, and has a small thickness. Hence, the CCFL backlight device is preferred to others.
The CCFL backlight device uses a direct or edge-light system and substantial effort has been made to study the edge-light system so as to cope with the demand for a thin and light-weighing display unit.
A backlight device for a monitor fabricated by a general edge-light system is explained as follows.
A backlight device for a general monitor, as shown in
FIG. 1
, includes a lamp
10
as a light sources emitting light, supported in frame
15
, a light-guiding plate
11
guiding the light emitted from the lamp
10
, a diffusion sheet
12
diffusing the light projected from the light-guiding plate
11
at a predetermined angle, a prism sheet
13
condensing the light diffusing from the diffusion sheet
12
so as to transfer the condensed light to an LCD panel unit
14
, an LCD panel unit
14
on the prism sheet
13
, a fixing mechanism (not shown in the drawing) under the light-guiding plate
11
, and a reflection sheet
16
for reflecting the light transferred to the fixing mechanism on the LCD panel unit
14
.
The backlight device further includes a lamp reflection sheet
18
disposed around the lamp
10
so as to reduce the loss of light projected from the lamp
10
and lamp holders
17
formed at both ends of the lamp
10
so as to fix the lamp
10
thereto as well as prevent contact between the light-guiding plate
11
and the lamp
10
.
Two species of backlight devices according to the related art can be explained by referring to the attached drawings as follows.
A first backlight device according to related art, as shown in
FIGS. 2A and 2B
, includes a reflection sheet
23
beneath a light-guiding plate
21
, a lamp reflection sheet
24
circumferential wrapping around the lamp
22
, supported in lamp holder
26
and a fixing mechanism
25
which partially wraps around the lamp reflection sheet
24
.
A second backlight device according to the related art, as shown in
FIGS. 3A and 3B
, includes a bottom reflection sheet
33
completely wrapping around the exterior of a lamp
32
, supported a lamp holder
35
except for the light-incident face of a light-guiding plate
31
so as to carry out the function of a lamp reflection sheet. In this case, the fixing mechanism
34
is constituted so as to surround a lower portion and one side of the bottom reflection sheet
32
.
The lamp reflection sheet
24
and the bottom reflection sheets
23
and
33
are made of materials having high reflectivity. In order to increase the reflective efficiency, metal is coated on the lamp reflection sheet
24
or a coating film is attached to the lamp reflection sheet
24
. The bottom reflection sheets
23
and
33
are made of thin materials which bring about mirror reflection or diffusion reflection.
However, the structure of each of the backlight devices according to the related art becomes complicated due to the lamp reflection sheet
24
surrounding the lamp
32
.
Moreover, when the bottom reflection sheet
33
extending for the function of a lamp reflection sheet is used, it is difficult to maintain the uniform shape to surround the lamp
32
since the bottom reflection sheet
33
is formed with a thin film.
SUMMARY OF THE INVENTION
The present invention is directed to a backlight device that substantially obviates one or more problems due to limitations and disadvantages of the related art.
Accordingly, an object of the present invention is to provide a backlight device which provided for light to be incident on a light-guiding plate without loss of the light generated from a lamp while at the same time simplifying the constitution of the backlight device.
Another object of the present invention is to provide a backlight device which stably fixes and protects the light-guiding plate and lamp.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from the practice of the invention. The objectives and other advantages of the invention may 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 objects and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, the backlight device of the present invention includes at least one lamp, a light-guiding plate for laterally receiving light emitted from the lamp and transferring the received light to an upper face, and a fixing mechanism surrounding the lamp and light-guiding plate for reflecting the light of the lamp toward the light-guiding plate, the fixing mechanism having at least one protrusion formed at an inner surface thereof.
Advantageously, the fixing mechanism is made of a material having a reflective function. More preferably, the fixing mechanism is made of a plastic material, e.g., a polyester or acrylic material. Also, a sheet or a film can be attached to or coated on the inner surface of the fixing mechanism which advantageously surrounds the entire lower face and a portion of the upper face of the light-guiding plate.
A protrusion can be located between the lamp and light-guiding plate for separating the lamp and light-guiding plate from each other. The light-guiding plate has a corresponding recess to accommodate to the protrusion for separating the lamps from the light-guiding plate.
The protrusion corresponding to the recess can be an uneven shape.
The lamp can be arranged at one side of the light-guiding plate or at both sides of the light-guiding plate. Preferably, the backlight device further includes lamp holders provided at both ends of the lamp for fixing the lamp in a predetermined position.
In another aspect of the present invention, the backlight device includes at least one lamp, a light-guiding plate for receiving light emitted from the lamp through a lateral face and transferring the received light to an upper face, a reflection sheet placed under the light-guiding plate and extending around the lamp
Birch & Stewart Kolasch & Birch, LLP
LG. Philips LCD Co. Ltd.
Tso Laura K.
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