Electric lamp and discharge devices – With luminescent solid or liquid material – With gaseous discharge medium
Reexamination Certificate
2001-06-29
2004-06-08
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
With gaseous discharge medium
C313S484000, C313S485000, C313S631000, C313S309000, C313S336000, C313S351000
Reexamination Certificate
active
06747404
ABSTRACT:
The present invention claims the benefit of Korean Patent Application No. 2000-80212 filed in Korea on Dec. 22, 2000, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flat type fluorescent lamp, and more particularly, to a flat type fluorescent lamp and a method for manufacturing the same.
2. Discussion of the Related Art
A back light used as a light source of a liquid crystal display (LCD) panel is created by an arrangement using a cylindrical fluorescent lamp. Such a back light can be a direct type or a light-guiding plate type.
In the direct type back light, the fluorescent lamp is mounted under the LCD panel. The shape of the fluorescent lamp can be seen on the display of the LCD panel due to unequal distribution of luminous intensity across the LCD panel if the fluorescent lamp is too close to the LCD panel. Therefore, it is necessary to maintain a distance between the fluorescent lamp and the LCD panel to enable a uniform distribution of luminous intensity across the LCD panel. Inherently, there is a minimum thickness limitation when attempting to form a thin size back light using a direct type back light.
In the light-guiding plate type, the fluorescent lamp is mounted outside LCD panel so that light is diverted to be dispersed uniformly across the back surface of the LCD panel using a light-guiding plate having printed dots. In this case, since the fluorescent lamp is mounted at one side and light passing through a side of the light-guiding plate has to be diverted so as to disperse the light across the LCD panel, a problem arises in that luminance is low. Also, for uniform distribution of luminous intensity, advanced optical design with regard to the dot pattern and processing technologies to maintain design dimensions are required.
FIG. 1
is a sectional view of a related art back light, and
FIG. 2
is an exploded perspective view of a related art back light. In
FIGS. 1 and 2
, a light-guiding plate type back light is shown in which linear light emitted from a lamp
10
is diverted so as to disperse across the LCD panel.
A portion of the related art back light is positioned under a back surface of a liquid crystal panel that displays an image. As shown in
FIG. 1
, the related art back light includes a main support
1
for supporting respective elements. In a portion of the main support
1
that will be positioned outside of the LCD panel that displays an image, the respective elements include a lamp assembly
10
used as a light source and a lower cover
3
for covering the main support
1
. In another portion of the main support
1
that will be under a back surface of the LCD panel that the respective elements include a reflector
4
positioned on the main support
1
for reflecting light into the LCD panel, a light-guiding plate
5
for uniformly supplying light irradiated from the lamp to the LCD panel, a lower light-diffusion plate
6
provided on an upper surface of the light-guiding plate
5
to diffuse the light emitted from the light-guiding plate
5
, a lower prism
7
provided on an upper surface of the lower light diffusion plate
6
for condensing the light emitted from the lower light-diffusion plate
6
, an upper prism
8
for further condensing light emitted from the lower prism
7
and an upper light-diffusion plate
9
provided on an upper surface of the upper prism
8
to diffuse light emitted from the upper prism
8
into the LCD panel.
An assembly process of the aforementioned related art back light will now be described with reference to FIG.
2
.
As shown in
FIG. 2
, spacers
14
are provided on the lamp to protect the lamp
11
. Then a high pressure lamp wire
13
a
connected to a connector
16
and a low pressure lamp wire
13
b
are respectively soldered to a high pressure side and a low pressure side of the lamp
11
. Lamp holders
12
a
and
12
b
are assembled to cover a soldering portion of the lamp so that the lamp holders
12
a
and
12
b
are mounted in a lamp housing
15
. Thus, a lamp assembly
10
is completed.
Subsequently, the lamp assembly
10
is positioned on the main support
1
and the lower cover
3
is attached to the main support
1
so that the lamp assembly is not damaged by external impact. Thereafter, a reflecting plate
4
is mounted on an inner surface of the main support
1
and a light-guiding plate
5
is mounted in an inner gap of the lamp housing
15
so as not to deform the gap size and flatness of the lamp housing
15
. Afterwards, the lower light-diffusion plate
6
, the lower prism
7
, the upper prism
8
, and the upper light-diffusion plate
9
are sequentially formed on the light-guiding plate
5
.
In such a related art back light, if the connector
16
is connected with a power supply to apply power to the lamp, a glow discharge occurs in the lamp, thereby emitting light. The emitted light is entered into a light incident surface of the light-guiding plate
5
. The light is then diverted by the light-guiding plate
5
using dots in a predetermined pattern within the light-guiding plate
5
and condensed in a vertical direction while passing through the prisms
7
and
8
. The light can scatter at oblique angles while passing through the light-diffusion plates
6
and
9
. Therefore, some of the light passes through the light-diffusion plates and illuminates the back surface of the LCD panel. The reflecting plate
4
serves to upwardly reflect through the light-guiding plate
5
the light that is directed downward due do the scattering of the light-diffusion plates
6
and
9
.
However, the related art back light has several problems. First, since the light is emitted from the side of the support using a cylindrical fluorescent lamp as a light source, it is difficult for the fluorescent lamp to generate a large amount of luminance across the entire surface of the main support that is under the back surface of an LCD panel.
Second, since the light-guiding plate uses dots in a predetermined pattern to upwardly divert the light entered from the side, it is difficult to appropriately control a surface state of the light-guiding plate and direction of light with the dot pattern.
Third, the related art back light requires various elements in an exact dimensional relationship with one another. For example, the light-guiding plate may be bent so as to no longer maintain the proper dimension with the light source or the bottom surface of the LCD panel. Particularly, deformation may occur due to the difference of expansion coefficient between sheet elements and other elements at a high temperature. The dimensional change of the light-guiding plate having greater absorption than the main support is a serious problem. In case of a notebook computer, deformation of the light-guiding plate may occur when folding and unfolding the notebook computer.
Fourth, the related art back light manufacturing process is complex, thereby reducing yield. Strict process management is required so as not to generate foreign materials that scratch the light-guiding plate, reflector, prisms or diffusers. In addition, it is impossible to assemble the fluorescent lamp using automated equipment, which increases the manufacturing cost due to labor costs. Furthermore, quality control is difficult to manage.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a flat type fluorescent lamp and a method for manufacturing the same 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 flat type fluorescent lamp that serves as an illuminating unit and a back light of a large sized liquid crystal panel.
Another object of the present invention is to provide a flat type fluorescent lamp that can be manufactured using an automated system to simplify parts sourcing and process steps, thereby improving yield and reducing the manufacturing cost.
Another object of the present invention is to provide a flat type fluorescent lamp and a method
Leurig Sharlene
LG.Philips LCD Co. , Ltd.
Morgan & Lewis & Bockius, LLP
Patel Nimeshkumar D.
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