Liquid crystal cells – elements and systems – Particular structure – Particular illumination
Reexamination Certificate
1999-01-14
2001-09-25
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Particular illumination
C362S026000, C362S035000
Reexamination Certificate
active
06295105
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display module, and more particularly to a backlight assembly for use of liquid crystal display (LCD) module, which is enhanced for a better luminance.
2. Description of the Related Art
Cathode ray tubes (CRTs) are primarily used for monitors of televisions, measuring instruments, or data terminals. However, such CRTs are large and heavy, and thus inappropriate for a tendency of size and weight reductions in the electronic appliances.
Liquid crystal display (LCD) devices are a well known form of flat panel display. Especially, the smaller, lighter and less power consumptive characteristics make the LCD devices considered as one of the most leading display devices for overcoming disadvantages of CRTs.
Differently from CRTs, the liquid of an LCD device which is injected between a thin film transistor (TFT) substrate and a color filter is not a light emitting element but a light receiving one that controls the amount of the light emitted from external devices so as to display onto a screen. Therefore, an additional light source, say, backlight unit, is absolutely necessary for irradiating the light onto the LCD panel.
Accordingly, performance of the backlight unit affects significantly to the quality of LCD devices.
Such a backlight unit is composed of various optical components.
As shown in
FIG. 1
, to prevent the LCD panel from being suffered from the lowered efficiency of the light, which may occur while the light is emitted to the LCD panel, the backlight unit employs a lamp cover
24
for covering the outer periphery of a fluorescent lamp
18
, and a back cover
28
for supporting the lamp cover
24
.
However, as shown in
FIG. 1
, if the lamp cover
24
and the back cover
28
contact at whole surfaces thereof, the heat which is generated when the lamp is turned on is transmitted to the back cover
28
through the lamp cover
24
. Accordingly, the time period for luminance saturation is delayed by the heat loss.
As expressed in the following Equation (1), a capacitor is in proportion to the size (S), and is in inverse proportion to the distance (L).
C
=
σ
S
L
Equation
(
1
)
Wherein, C indicates the capacitance, &sgr; indicates the dielectricity, S indicates the size of the contact area between conductors, and L indicates the distance between conductors.
However, the distant-L
1
between the lamp cover
24
and the back cover
28
is just 0.05 mm, which increases size (S) of the contact area between the lamp cover
24
and the back cover
28
during assembly. As a result, the value of the capacitance (C) becomes larger, which causes an increase in current leakage and lowering of the luminance. In addition, the size of the contact area increases, thus extending the time period for luminance saturation.
When the SIC-130 inverter is used in the simulation, the estimated luminance is approximately 100 nit at the current of 5 mA, the current leakage is approximately 1.25 mA, and the time period for luminance saturation is 40 to 50 minutes.
Moreover, the luminance of the lamp of the backlight unit varies in accordance with the ambient temperature. The luminance of the lamp becomes the highest when the ambient temperature is about 40° C. to 50° C. However, the back cover is made of a metal, which emits a heat. Thus, the temperature around the lamp is dropped down and the luminance is lowered.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to prevent a luminance degradation of a backlight unit.
It is another object of the present invention to minimize the time period for stabilizing the luminance of the backlight unit.
It is still another object of the present invention to minimize the current leakage of the lamp.
According to an aspect of the present invention, there is provided a lamp assembly for use of LCD module including a back cover having a plurality of penetrating holes with a predetermined diameter. To minimize the contact area between the back cover and the lamp cover, the surface of the back cover is provided with a plurality of embossings or beadings which are formed in the direction at which the back cover contacts the lamp cover.
Selectively, each contact surface of the back cover and the lamp cover is laminated using an insulator, for example, polyethylene terephthalate (PET).
According to another aspect of the present invention, a plurality of penetrating holes for a temperature radiation are formed to the lamp cover. Selectively, a silver (Ag)-plated film is coated on the surface of the lamp cover facing the fluorescent lamp.
According to still another aspect of the present invention, the sufficient distance between the back cover and the lamp cover is maintained, and a buffer member, for example, a cushion, is inserted therebetween. If the distance between the lamp cover and the back cover is 0.4 mm, the preferable thickness of the cushion is 0.3 mm.
According to further another aspect of the present invention, the lamp assembly for use of LCD module is structured in that only a lamp cover is provided without a back cover.
REFERENCES:
patent: 05-93908 (1993-04-01), None
patent: 6-34818 (1994-02-01), None
patent: 10-186339 (1998-07-01), None
patent: 11-34120 (1999-02-01), None
patent: 11-231321 (1999-08-01), None
Kim Jung-ki
Lee Jeong-hwan
Lee Sang-duk
Shin Chung-hyuk
Howrey Simon Arnold & White , LLP
Parker Kenneth
Samsung Electronics Co,. Ltd.
LandOfFree
Enhanced backlight assembly for a liquid crystal display does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Enhanced backlight assembly for a liquid crystal display, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Enhanced backlight assembly for a liquid crystal display will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2441920