Back light device

Details Back light device Back light device

2002-06-26

2004-09-21

Husar, Stephen (Department: 2875)

Illumination

Plural light sources

With modifier

C362S225000, C362S260000, C362S249070, C362S235000

Reexamination Certificate

active

06793370

ABSTRACT:

The present invention claims benefit of Korean Application No. P2001-45439 filed in Korea on Jul. 27, 2001, which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a back light device, and more particularly, to a back light device for a liquid crystal display.
2. Background of the Related Art
Presently, flat panel display devices have display screens of no more than a few centimeters. The devices, in particular liquid crystal display (LCD) devices, have a wide field of applications including notebook computers, monitors, spacecraft, and aircraft, for example. The LCD devices have a back light device disposed at a rear portion of the LCD panel to function as a light source. The back light device commonly includes a cylindrical fluorescent lamp arranged in either one of a direct lighting-type or a side lighting-type configuration.
The direct lighting-type back light device is problematic since a minimum gap is required to be maintained between the cylindrical fluorescent lamp and the LCD panel in order to prevent an image of the cylindrical fluorescent lamp from appearing on the LCD panel. In addition, a light diffusing system is required to provide a uniform distribution of light. Moreover, the advent of large sized display panels requires an increased light emission surface area of the back light device. Accordingly, the light emission surface area must be of an adequate thickness to prevent any deformation associated with the increased size.
The side lighting-type back light device includes the fluorescent lamp disposed along a circumference of the LCD panel and a light plate is used for diffusing light emitted from the fluorescent lamp over an entire surface of the light plate. Accordingly, the side lighting-type configured back light is problematic since the intensity of the emitted light is low. In addition, fabricating technologies are required for manufacturing the light plate in order to provide a uniform distribution of the emitted light.
Thus, the direct lighting-type back light device is commonly used in LCD devices when brightness of the emitted light is more important than an overall thickness of the LCD screen, and the side lighting-type back light device is commonly used in LCD devices when the overall thickness of the LCD screen is more important, such as a notebook personal computer or a monitor for a personal computer. Accordingly, a back light device having both high brightness and small thickness is needed.
FIG. 1
is a perspective view of a direct lighting-type back light device according to the related art. In
FIG. 1
, the back light device includes a plurality of light emitting lamps
1
, an outside case
3
for fastening and holding the light emitting lamps
1
, and an optical diffusing system
5
a
,
5
b
, and
5
c
arranged between the light emitting lamps
1
and an LCD panel (not shown).
A plurality of diffusion sheets and diffusion plates are disposed between the LCD panel and the plurality of light emitting lamps for preventing an image of the light emitting lamp
1
from being displayed onto a display surface of the LCD panel. A reflecting plate
7
is disposed on an inside surface of the outside case
3
for focusing the light emitted from the light emitting lamp
1
onto a display portion of the LCD panel, thereby efficiently utilizing the emitted light.
FIG. 2
is a perspective view of a light emitting lamp and a connector configuration according to the related art. In
FIG. 2
, the light emitting lamp
1
, which is commonly referred to as a cold cathode fluorescent lamp (CCFL), has electrodes
2
a
and
2
b
formed on opposite ends inside a tube for emitting light when a power source is applied to the electrodes
2
a
and
2
b
. The opposite ends of the light emitting lamp
1
are inserted into recesses formed in both surfaces of the outside case
3
. The light emitting lamp
1
includes power lines
9
a
and
9
b
connected to the electrodes
2
a
and
2
b
for providing the power source for operating the light emitting lamp
1
. The power lines
9
a
and
9
b
are connected to a connector
11
that is connected to a driving circuit (not shown). Accordingly, every light emitting lamp
1
requires a separate connector
11
, wherein one of power lines
9
a
and
9
b
is bent to correspond to a lower part of the outside case
3
before being connected to the connector
11
.
The light emitting lamp
1
and connector
11
configuration is complicated since separate power lines
9
a
and
9
b
and connector
11
are required for each lamp. Accordingly, working efficiency and productivity decreases since more fabrication time is required to bend the power lines
9
a
and
9
b
and connect each of the light emitting lamps
1
to the connectors
11
. Moreover, since the electrodes
2
a
and
2
b
must be fed through a hole formed in the outside case and attached to the connector
11
, working efficiency is poor, and maintenance of the light emitting lamp is difficult.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a back light device 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 a back light device that can be easily maintained.
Another object of the present invention is to provide a back light device that can improve light emitting lamp efficiency.
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 back light device includes a plurality of light emitting lamps, upper and lower holders having a plurality of recesses in opposing surfaces for receiving opposite ends of each the plurality of light emitting lamps, conductive layers on the opposing surfaces of the upper and lower holders for supplying power to opposite ends of the light emitting lamps, a conductive material on the conductive layers, and a light diffusion system over the upper holders.
In another aspect, a back light device includes a plurality of light emitting lamps, upper and lower holders having a plurality of recesses in opposing surfaces for receiving the plurality of light emitting lamps, conductive layers on the opposing surfaces of the upper and lower holders for supplying power to the light emitting lamps, an elastic material under the conductive layers, and a light diffusion system over the upper holders.
In another aspect, a back light device includes a plurality of light emitting lamps, first and second lower holders arranged a first distance apart from each other to fit to a length of the light emitting lamps, each of the first and second lower holders having a first plurality of recesses for receiving opposite ends of the plurality of light emitting lamps, first and second upper holders arranged the first distance apart from each other, each of the first and second upper holders having a second plurality of recesses corresponding to the first plurality of recesses for fastening and holding the opposite ends of the light emitting lamps together with the first and second lower holders, conductive layers on opposing surfaces of the first and second lower and upper holders for supplying power to the light emitting lamps, and a conductive material on the conductive layers.
In another aspect, a back light device includes a plurality of light emitting lamps, first and second lower holders arranged a first distance apart from each other to fit to a length of the light emitting lamps, each of the first and second lower holders having a first plurality of recesses for receiving opposite

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