Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-01-03
2003-12-16
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S073000, C349S096000, C349S123000
Reexamination Certificate
active
06665034
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a display panel device, a display panel unit and a display device for use in a liquid crystal display device and the like.
As a display device for a personal computer or other various monitors, a liquid crystal display device has been remarkably widespread. Such a liquid crystal display device is generally constituted in such a manner that a backlight as a planar light source is disposed on a back of a display panel to irradiate a liquid crystal surface of a specified expanse with an even bright light as a whole, and that an image formed on the liquid crystal surface of the display panel can be thereby visualized.
In the case of achieving enlargement of the liquid crystal display device as described above, under the present situation, since enlargement of the display panel itself has limitations, as shown in
FIG. 6
, a plurality of display panels
2
are arranged, and the display panels
2
and
2
adjacent to each other are adhered together, thus constituting a large-sized liquid crystal display device. In such a case, each of the display panels
2
is referred to as a tile panel.
Heretofore, in the display panel
2
, data lines and scan lines for driving liquid crystal have been provided in a matrix fashion, and on two sides of the display panel
2
, drive circuit portions
3
and
4
for the data lines and the scan lines are provided, respectively. For this reason, up to now, enlargement of a liquid crystal display device has been previously limited to a formation of four display panels
2
at the maximum, i.e., 2 vertical panels by @2 horizontal panels.
On the contrary, integration of the drive circuit portions
3
and
4
for the data lines and the scan lines in a matrix fashion has been developed as an integrated drive circuit portion, which is provided only on one side of the display panel
2
. Thus, a liquid crystal display device extending long in one direction has become formable by connecting many pieces of the display panels
2
in either the vertical or the horizontal direction.
However, when the liquid crystal display device is enlarged as described above, first, there is a problem of a viewing angle characteristic. Specifically, in the case of enlarging the liquid crystal display device, for example, when the viewing angle characteristic of each display panel
2
is set with a center portion of a display area taken as a reference, there occurs such a problem as that it is difficult to see display contents in the periphery of the display area.
For the problem, various proposals have been made in order to improve the viewing angle characteristic on the entire display area of the large-sized liquid crystal display device. Basically, the viewing angle of the display panel
2
depends on a direction of rubbing performed on a substrate constituting the display panel
2
, which regulates an aligning direction of the liquid crystal in the display panel
2
. For example, in the gazettes of Japanese Patent Laid-Open Nos. Sho 60 (1985)-156048 and Hei 7 (1995)-140461, a liquid display device in which rubbing of a substrate is performed in different directions depending on a position of the display panel
2
in the display area thereof has already been proposed.
As a mode offering a more excellent viewing angle characteristic as compared with a twisted nematic (hereinafter abbreviated as TN) mode typically used in the display panel
2
, an in-plane switching (IPS) mode and a vertical alignment (VA) mode are mentioned. Moreover, there is another type of the display panel
2
, which is capable of improving the viewing angle characteristic even though a TN mode is used therein. As shown in
FIG. 7
, the display panel
2
of this type includes: a light collection member
6
for collecting a planar light irradiated from a backlight
5
thereon; and a diffusion member
7
for diffusing the light collected by the light collection member
6
and transmitted through the display panel
2
, wherein the collection member
6
is disposed below the display panel
2
, and the diffusion member
7
is disposed above the display panel
2
. Improvement of the viewing angle characteristic is conceivable by adopting these constitutions into a large-sized liquid crystal display device.
However, in any of the cases as described above, when the liquid crystal display device is enlarged, there is another problem that a size thereof is limited by polarizing plates disposed above and below the display panel
2
. As shown in
FIGS. 7 and 8
, a polarizing plate
8
A for controlling light incident onto the display panel
2
is provided above the display panel
2
, and a polarizing plate
8
B for controlling light emitted from the display panel
2
is provided below the display panel
2
. As shown in
FIG. 8
, for example, in the case of an o (ordinary)-mode, the polarizing plates
8
A and
8
B have optical absorption axes in directions shown by arrows (a), respectively. These polarizing plates
8
A and
8
B are severally provided with the direction of the absorption axis thereof based on the rubbing direction of the display panel
2
as a standard. When the liquid crystal display device is of a normally white mode, a state as shown in
FIG. 8
is set, where the absorption axis of the polarizing plate
8
A is allowed to coincide with a rubbing direction (b) of an upper substrate
2
a
, and the absorption axis of the polarizing plate
8
B is allowed to coincide with a rubbing direction (c) of a lower substrate
2
b
. When the liquid crystal display device is of a normally black mode, both of the absorption axes of the polarizing plates
8
A and
8
B are allowed to coincide with the rubbing direction of the upper substrate
2
a.
The directions of the absorption axes of the polarizing plates
8
A and
8
B, as shown in
FIG. 9
, depend on an extending direction (d) of a film-like material during fabrication thereof. In order to set the absorption axes of the polarizing plates
8
A and
8
B in directions approximately diagonal thereto, the polarizing plates
8
A and
8
B must be laid out aslant on a material
9
when the polarizing plates
8
A and
8
B are cut out of the material
9
extended in the direction shown by an arrow (d). Such a layout is applicable not only in the case of the o-mode, shown in
FIG. 8
, but also in the case of e (extraordinary)-mode.
Therefore, each size of the polarizing plates
8
A and
8
B, which can be cut out, has been forced to be significantly smaller with respect to a width W of the material
9
, resulting in limitations of a size of the liquid crystal display device, particularly, a vertical size thereof. Moreover, since the polarizing plates
8
A and
8
B are laid out aslant to the material
9
and cut out, a yield of the material
9
is lowered, thus hindering the reduction of material costs.
In addition to the above-described problems, in the constitution using the light collection member
6
and the diffusion member
7
as shown in
FIG. 7
, the enlargement of the light collection member
6
and the diffusion member
7
has limitations, and further, transmission of light through the light collection member
6
and the diffusion member
7
causes an optical loss.
SUMMARY OF THE INVENTION
The present invention was made with the foregoing technical problems in mind. A principal object of the present invention is to provide a display panel device, a display panel unit and a display device, which are capable of achieving enlargement thereof and of reducing material costs of the polarizing plates. Another object of the present invention is to provide a display panel device, a display panel unit and a display device, which are capable of improving a viewing angle characteristic even in the case of enlargement thereof.
In order to achieve the foregoing objects, a display panel device of the present invention is characterized in that directions of aligning treatment for two substrates of a display panel are allowed to coincide with a vertical direction and a horizontal direction of the display panel device ind
Blecker Ira D.
Chowdhury Tarifur R.
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