Direct type back light device

Details Direct type back light device Direct type back light device

2002-06-26

2004-06-15

Husar, Stephen (Department: 2875)

Illumination

Display backlight

Lcd backlight

C362S033000, C362S225000, C362S249070, C362S260000, C362S396000, C362S224000, C362S240000, C313S318100

Reexamination Certificate

active

06749315

ABSTRACT:

The present invention claims the benefit of the Korean Patent Application No. P2001-68568 filed in Korea on Nov. 5, 2001, which is 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 direct-type back light device for a liquid crystal display (LCD) device.
2. Discussion 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-type or a lighting guiding plate-type configuration.
The direct-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 scattering 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 light guiding plate-type back light device uses a fluorescent lamp that is provided at a side of a light guiding plate to disperse light emitted from the fluorescent lamp onto an entire flat panel display using the light guiding plate. However, the light guiding plate-type back light device is problematic since the combination of the fluorescent lamp and the light guiding plate causes low luminance of the flat panel display. In addition, advanced optical design and processing technologies are required to provide uniform distribution of luminescent intensity.
The direct-type back light device and the light guiding plate-type back light device each have their own unique problems. For example, direct-type back light devices are commonly used in monitors for personal computers and for televisions because of their relatively high display intensity where overall thickness of the device is unimportant, and light guiding plate-type back light devices are commonly used in notebook computers because of their relatively small overall thickness where display intensity is not very important
FIG. 1
is a perspective view of a direct-type back light device according to the related art. In
FIG. 1
, the direct-type back light device includes a plurality of luminescent lamps
1
, an outer case
3
that fixes and supports the luminescent lamps
1
, and light scattering system
5
a
,
5
b
, and
5
c
arranged between the luminescent lamps
1
and an LCD panel (not shown). The light scattering system
5
a
,
5
b
, and
5
c
prevents an image of the luminescent lamps
1
from being displayed onto a display screen (not shown) of the LCD panel, and provides for a uniform distribution of light emitted from the luminescent lamps
1
. To further enhance a light-scattering effect of the light scattering system
5
a
,
5
b
, and
5
c
, a plurality of diffusion sheets and a plurality of diffusion plates are arranged between LCD panel and the luminescent lamps.
The outer case
3
includes a reflecting plate
7
disposed at an interior of the back light device. The reflecting plate
7
is arranged to focus the light emitted from the luminescent lamp
1
onto a display part of the LCD panel, thereby enhancing light efficiency.
The luminescent lamp
1
is commonly referred to as a cold cathode fluorescent lamp (CCFL) and functions as a light source of an LCD device when a power source is supplied to electrodes
2
a
and
2
b
arranged at opposite ends of the luminescent lamp
1
. The opposite ends of the luminescent lamp
1
fit into grooves formed at opposing sides of the outer case
3
. The electrodes
2
a
and
2
b
are connected to power lines
9
a
and
9
b
to drive the luminescent lamp
1
. The power lines
9
a
and
9
b
are fastened to a connector
11
for electrical connection to a driving circuit (not shown). Accordingly, a separate connector
11
is required for each luminescent lamp
1
. Moreover, one of the power lines
9
a
and
9
b
is curved downwardly toward the outer case
3
and then connected to the connector
11
.
However, the back light device according to the related art is problematic. First, since the connector
11
is connected between the power lines
9
a
and
9
b
of the luminescent lamp
1
and the driving circuit, a separate connector
11
is required for each luminescent lamp
1
. Accordingly, the total number of power lines and connectors becomes very complicated. Moreover, since the power lines
9
a
and
9
b
must be separately bent to reduce an overall thickness of the back light device, work processing time increases and productivity deteriorates.
Second, a hole must be formed to pass through the outer case
3
so that the electrodes
9
a
and
9
b
are fastened to the connector
11
. Accordingly, since the electrodes
9
a
and
9
b
must be individually fit through the hole to be exposed at an exterior of the outer case
3
, efficiency of the manufacturing process is reduced and any required repairs would not be easily facilitated.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a direct-type back light device that substantially obviates one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a direct-type back light device that enhances efficiency of the manufacturing process and facilitates repair.
Another object of the present invention is to provide a direct-type back light device that improves light efficiency and prevents damage to the luminescent lamp from external impact.
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 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 invention, as embodied and broadly described herein, a direct type back light device includes a plurality of luminescent lamps, upper and lower lamp holders formed to receive upper and lower opposite ends of the luminescent lamps, a lower support having lower lamp holder recesses for fixing the lower lamp holders, conductive layers formed upon an area of the lower lamp holders and lower support for receiving the lower opposite ends of the luminescent lamps to supply power to the luminescent lamps, an upper support having upper lamp holder recesses for fixing the upper lamp holders, and conductive layers formed upon an area of the upper lamp holders and upper support for receiving the upper opposite ends of the luminescent lamps to supply the power to the luminescent lamps, wherein the lower and upper supports assemble together to fix the lower and upper opposite ends of the luminescent lamps.
In another aspect, a direct type back light device includes a plurality of luminescent lamps, lower supports each having a first lower base portion and an interconnecting first upper base portion, conductive layers formed upon the lower supports for receiving the lower opposite ends of the luminescent lamps to supply power to the luminescent lamps, upper supports each having a second lower base portion and an interconnecting second upper base portion; and conductive layers formed upon the upper supports f

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