Liquid crystal cells – elements and systems – Particular structure – Holder – support – frame – or housing
Reexamination Certificate
1998-12-04
2001-09-18
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Holder, support, frame, or housing
C349S061000
Reexamination Certificate
active
06292239
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a liquid crystal display used for a personal computer or the like, and more particularly, to a frame structure suitable for realization of a thin and lightweight liquid crystal display and the structure of a back light unit in the liquid crystal display.
2. Description of the Background Art
A frame constituting a liquid crystal panel unit for use in a liquid crystal display has been conventionally used for holding a liquid crystal panel and a back light unit. The back light unit is constituted by a plurality of components which are represented by a lens sheet, a photoconductive plate, a diffusion sheet, a reflection sheet, and an electric-discharge lamp. Therefore, it is necessary to fix the back light unit separately using a holding component in order to complete the liquid crystal display.
FIGS. 17 and 18
illustrate respectively examples of frame structures for a liquid crystal display which have been conventionally employed. In the frame structure shown in
FIG. 17
, a photoconductive plate
102
is only put on a frame
101
. Therefore, the photoconductive plate
102
is fixed to the frame
101
using a fastener
103
in order to complete the liquid crystal display.
In the frame structure shown in
FIG. 18
, a frame
104
is held in a sheathing plate
107
, only to hold a photoconductive plate
105
and a liquid crystal panel
106
. Therefore, a liquid crystal unit
109
is fixed to a cabinet of the main body of the liquid crystal display by a screw hole
108
provided in the sheathing plate
107
. The above-mentioned conventional liquid crystal display is thus constituted by a frame for supporting each of components constituting the back light unit, a fastening component for fastening the frame and the components constituting the back light unit, and a sheathing plate for holding the frame. Therefore, the number of components is large, so that the liquid crystal display is thick and is heavy.
At the same time, the liquid crystal display is widely employed for applications such as a portable notebook-sized personal computer and a portable liquid crystal TV. Such a portable liquid crystal display is driven by a battery, so that power consumed by the liquid crystal display prevents battery life from being lengthened. Power consumed by a back light used for the liquid crystal display is very large in the consumed power. The optical efficiency of the back light is improved, to increase the luminance of a display screen by small consumed power, thereby lengthening the battery life.
FIG. 19
illustrates the general construction of such a back light. In
FIG. 19
, reference numeral
50
denotes a light source such as an electric-discharge lamp, which is arranged opposite to a side surface of a photoconductive plate
51
. In order to effectively introduce light into the photoconductive plate
51
from the light source
50
, the rear surface of the light source
50
is covered with a reflection sheet
52
. A reflection sheet
53
is closely superimposed on the lower surface of the photoconductive plate
51
, and a diffusion plate
54
and lens sheets
55
and
56
are closely superimposed on the upper surface thereof, to constitute a back light unit
57
. A liquid crystal panel
58
is arranged at some distance above the back light unit
57
, to constitute a liquid crystal panel unit.
Light irradiated from the light source
50
is incident on the photoconductive plate
51
, and the light travels in the photoconductive plate
51
to expand over the whole surface thereof, and is incident on the lens sheets
55
and
56
through the diffusion plate
54
. The incident light is refracted in the lens sheets
55
and
56
toward a viewer, to converge in his or her field of vision at an angle of less than approximately 70 degrees. Light which reaches the viewer is doubled by inserting the lens sheets
55
and
56
. Each of the lens sheets
55
and
56
is constructed by arranging very small prisms on a transparent film. The lens sheets
55
and
56
are made different in the angles of view in the X and Y directions by making the directions in which the prisms are arranged perpendicular to each other. In
FIG. 19
, an array of prisms in the lens sheet
56
is drawn in a vertical direction, and the lens sheet
55
is drawn in a horizontal direction. The optical efficiency of the back light is improved by arranging the lens sheets
55
and
56
thus constructed in a correct direction and in a correct order on the diffusion plate
54
, thereby making it possible to increase the luminance of the display screen of the liquid crystal display by small consumed power.
FIG. 20
illustrates an example of positioning of lens sheets in a conventional back light unit. In
FIG. 20
, reference numeral
59
denotes a supporting member for supporting lens sheets
55
and
56
, and reference numeral
60
denotes a notch provided at corners of the lens sheets
55
and
56
. The notch
60
prevents one of the surface and the reverse surface of each of the lens sheets
55
and
56
from being mistaken for the other in assembling the lens sheets.
In this method, however, it is difficult to find out, even if in inherently inserting two lens sheets, insertion of one of them is forgotten, that the insertion has been forgotten. It is impossible to confirm the order in which the lens sheets
55
and
56
are inserted even if they are both inserted. Further, the diffusion plate
54
, the photoconductive plate
51
, and the reflection sheet
53
are inserted with them being superimposed on the lens sheet
56
, and thus it cannot be physically confirmed whether or not the components constituting the back light unit
57
are correctly mounted after completion of the back light unit
57
.
Therefore, a unit has been conventionally inspected by mounting the liquid crystal panel
58
and operating the display screen to observe the luminance, the viewing angle, and so forth. As a result of the inspection, there are only measures to drop the component constituting the back light unit
57
, whose operation is judged to be abnormal, from an assembly line, and decompose and repair the liquid crystal panel
58
and the back light unit
57
.
Therefore, the present invention makes, as a personal computer is made small in size, thin, and lightweight, a liquid crystal display carried thereon small in size, thin, and lightweight. Further, an object of the present invention is to provide a back light unit, in the liquid crystal display, capable of preventing one of the surface and the reverse surface of each of lens sheets to be inserted from being mistaken for the other and preventing an erroneous number of lens sheets from being inserted in assembly processes of the back light unit as well as visually confirming the number of lens sheets to be inserted and the order in which the lens sheets are inserted even after assembling the back light unit.
SUMMARY OF THE INVENTION
A first aspect of the present invention is directed to a liquid crystal display wherein a liquid crystal panel for displaying an image and a back light unit for lighting the liquid crystal panel from the backside thereof so that the liquid crystal panel displays the image clearly are united into a liquid crystal panel unit by a frame and installed in a cabinet.
The frame comprises:
a projection extending around an inner wall at a first predetermined distance measured from one side edge of the inner wall and parallel to the side edge to divide the inner wall into two portions;
a first container, formed by the projection and one portion of the inner wall having a width defined by a first predetermined distance from the projection, for containing the liquid crystal panel therein; and
a second container, formed by the projection and the other portion of the inner wall, for containing the back light unit therein,
wherein the liquid crystal panel and the back light unit are united into the liquid crystal panel unit by the frame.
As is apparent from the above, according to the fi
Nagamura Yoshiaki
Yasuoka Shuji
Matsushita Electric - Industrial Co., Ltd.
Parker Kenneth
Qi Mike
Wenderoth , Lind & Ponack, L.L.P.
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