Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1997-12-03
2001-07-03
Wu, Xiao (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S098000
Reexamination Certificate
active
06256004
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to liquid crystal display devices which can be used in audio vidual (AV) equipment and office automation (OA) machines, and easily provide large-area displays.
BACKGROUND OF THE INVENTION
There have been demands for light weight, thin, low power-consuming, high definition, large-area display devices for use in AV equipment like home-use television sets and in OA machines. Therefore, the development of large-area displays for actual applications has been carried out in respect of display devices such as cathode ray tube display (CRT), liquid crystal display (LCD), plasma display (PDP), electro-luminescence display (EL) and light emitting diode display (LED).
In particular, liquid crystal display devices are advantageous because they can have much smaller thickness (depth) and power consumption, and easily provide a full-color display compared to display devices of other types. For this reason, in resent years, liquid crystal display devices have been used in various fields, and large-area liquid crystal displays have been greatly expected.
However, when fabricating a large-area liquid crystal display device with a conventional structure, the ratio of defects such as disconnection of signal lines and defective pixels abruptly increase during the fabrication process. The increase in the defection ratio causes such a problem that the price of the liquid crystal display device rises. In order to solve this problem, a large-area liquid crystal display device has been fabricated by simply connecting a plurality of liquid crystal panels together.
However, in the large-area liquid crystal display device fabricated in this method suffers from drawbacks that the joint in a display formed by the liquid crystal panels is noticeable, and displayed images have degraded display quality. In order to obtain natural displayed images, it is necessary to render the joint in the display of the liquid crystal display panels less noticeable.
Therefore, as a method for making the joint in the display of a large-area liquid crystal display device less noticeable, the present inventors proposed to dispose three pixel electrodes corresponding to red (R), green (G) and blue (B) filters at positions which are separated from the connected section of the liquid crystal panels by the same distance in Japanese Publication of Unexamined Patent Application No. 146455/1996 (Tokukaihei 8-146455).
In a large-area liquid crystal display device fabricated in this method, as illustrated in
FIG. 13
, liquid crystal panels
101
include pixels
113
arranged in matrix form, and each pixel
113
includes three pixel electrodes
114
which corresponds to R, G and B filters and are arranged in the order R, G and B (hereinafter referred to as the RGB order) so as to be separated from a connected section
111
by substantially the same distance. More specifically, the three pixel electrodes
114
are aligned in a direction parallel to the connected section
111
(the Y-axis direction in
FIG. 13
) that is an up-and-down direction of a displayed image (for example, a building) on the display.
As shown in
FIG. 14
, the pixels
113
are driven by TFT elements
115
which are respectively connected to the pixel electrodes
114
corresponding to R, G and B. Specifically, the TFT elements
115
are connected to signal lines
117
and scanning lines
118
which are respectively insulated by insulating films
116
. Each of the pixel electrodes
114
is independently driven by the TFT element
115
.
In this structure, even when light passing through the color filters corresponding to the pixels
113
located adjacent to the connected section
111
is refracted or scattered in the connected section
111
, the degree of color modulation is substantially uniform in the respective pixels
113
. Therefore, the color balance of light does not vary with respect to light coming from a direction oblique to the pixels
113
near the connected section
111
, thereby preventing regions of different color tones from being produced in the connected section
111
. Consequently, the joint in the large-area liquid crystal display becomes less noticeable.
Thus, by joining two pieces of liquid crystal panels together and rendering the joint in the display less noticeable, it is possible to provide displayed images with high quality.
However, in the alignment of pixel electrodes according to the method of the above-mentioned publication, Japanese Publication of Unexamined Patent Application No. 146455/1996, the length of each signal line
117
becomes at least twice longer than that of a conventional structure. Therefore, the delay of an electric signal functioning as a drive signal for providing a displayed image in the signal line
117
increases, causing vicious effects on the displayed image.
More specifically, in a conventional active-matrix type liquid crystal display device performing line-sequential scanning, signal lines are provided along the Y-axis direction shown in FIG.
14
. In such a device, scanning lines are provided along the X-axis direction shown in
FIG. 14
that crosses at right angles with the Y-axis direction. As described above, the Y-axis direction is the up-and-down direction (vertical direction) of a displayed image, for example, a building on the display, and the X-axis direction is the lateral direction of the displayed image.
Meanwhile, in a liquid crystal display device fabricated according to the method disclosed in Japanese Publication of Unexamined Patent Application No. 146455/1996, the pixel electrodes
114
are driven by drive signals similar to those of the conventional active-matrix type liquid crystal display device. In this device, the signal lines
117
are arranged in a shape like a square bracket around the pixel electrodes
114
so that the signal lines
117
are provided along the Y-axis direction. Consequently, the length of each signal line becomes at least twice longer than that of the conventional structure. Hence, in a large-area liquid crystal display device, when the signal lines
117
are arranged in such a manner, electric signals are delayed, causing vicious effects on displayed images.
In addition, since the number of crossings where the scanning lines
118
intersect the signal lines
117
through the insulating films
116
therebetween increases, defects are likely to occur due to an electrical short circuit at the crossings.
SUMMARY OF THE INVENTION
In order to solve the above problems, it is an object of the present invention to provide a liquid crystal display device capable of improving the quality of displayed images and reduce the ratio of defects by maintaining an arrangement of pixel electrodes for rendering the joint in the display less noticeable and adopting a simpler structure of signal lines and scanning lines, and provide a method of driving the liquid crystal display device.
In order to achieve the above object, a liquid crystal display device of the present invention has a liquid crystal panel including:
a plurality of pixels arranged in a matrix form;
a plurality of color filters provided in each of said pixels for enabling the pixels to provide a color display, the color filters in each pixel being arranged in a first direction corresponding to an up-and-down direction of a displayed image to be obtained;
pixel electrodes corresponding to the color filters, respectively;
a plurality of scanning lines arranged in the first direction for driving the pixel electrodes; and
a plurality of signal lines arranged in a second direction intersecting the first direction for driving the pixel electrodes.
In this structure, by driving the pixel electrodes corresponding to the respective color filters through the scanning lines and signal lines, the pixels can provide a color display. Moreover, by arranging the scanning lines along the first direction, it is possible to arrange the signal lines in straight lines along the second direction. Namely, unlike the conventional structure, there is no need to arrange the sinal lines in the for
Izumi Yoshihiro
Matsuura Manabu
Shinomiya Tokihiko
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
Wu Xiao
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