Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-05-30
2004-03-02
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S084000, C345S087000, C345S089000, C345S090000, C345S094000, C345S098000, C345S101000
Reexamination Certificate
active
06700560
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display device for color displaying. For example, the present invention relates to the liquid crystal display device for the color displaying with a liquid crystal panel having color filters of a vertical-stripe type, a mosaic type or a like built therein, and capable of adjusting white balance of a display screen thereof.
The present application claims priority of Japanese Patent Application No.2000-160804 filed on May 30, 2000, which is hereby incorporated by reference.
2. Description of the Related Art
As shown in
FIG. 18
, a conventional liquid crystal display device includes: a liquid crystal panel
1
, a signal electrode drive circuit
2
, a scanning electrode drive circuit
3
, and a control circuit
4
. The liquid crystal panel
1
includes color filters where a pixel is divided into sub-pixels of three primary colors of RGB (Red, Green, Blue). The liquid crystal panel
1
also includes: a plurality of data signal lines X
1
, . . . , Xn for receiving a sub-pixel data signal D
2
corresponding to the sub-pixels of RGB, a plurality of scanning signal lines Y
1
, . . . , Ym for receiving a scanning signal V
3
, and a plurality of sub-pixel regions provided at points where each of the data signal lines X
1
, . . . , Xn and each of the scanning signal lines Y
1
, . . . , Ym intersect. The sub-pixel data signal D
2
is supplied to sub-pixel regions selected from the plurality of sub-pixel regions by a scanning signal V
3
, and thus a color image corresponding to the sub-pixel data signal D
2
is displayed.
The signal electrode drive circuit
2
receives a clock signal ck, a control signal Ct, an image signal V
4
for each of RGB, and a central voltage Vs
1
, generates the sub-pixel data signal D
2
by selecting a gradation voltage corresponding to a gradation value of the image signal V
4
for each of RGB, and sends the sub-pixel data signal D
2
to each of the data signal lines X
1
, . . . , Xn of the liquid crystal panel
1
. The scanning electrode drive circuit
3
sends the scanning signal V
3
to each of the scanning signal lines Y
1
, . . . , Ym of the liquid crystal panel
1
synchronously with the clock signal ck. The control circuit
4
outputs the clock signal ck, the control signal Ct, the image signal V
4
, and the central voltage Vs
1
.
FIGS.
19
(
a
),
19
(
b
), and
19
(
c
) are exemplary views showing the above-mentioned color filters used in the liquid crystal panel
1
.
The color filter of a vertical-stripe type shown in FIG.
19
(
a
) is suitable for displaying characters, drawings, and the like. The color filters of a mosaic type and a triangle type shown in FIG.
19
(
b
), and
19
(
c
) are ones where the three primary colors of RGB are arranged in a delta state such as stacked-up bricks, which are suitable for displaying moving images such as television (that is, picture data displaying). There is also a horizontal-stripe type color filter. In the horizontal-stripe type color filter, a horizontal line is constituted of pixels of one of the RGB colors, and a line in the vertical direction is constituted of pixels of the three primary colors of RGB.
Adjustment of white balance of a display screen is generally performed by limiting a range of a gradation value of an image signal for each of RGB to be used. For example, in the case where the gradation value of each of RGB is represented by 8-bit data, the gradation value could take values in a range of from 0 to 256. In adjusting the white balance, however, top and bottom of the gradation value of a particular color are cut. For example, regarding the gradation value for R, 0 to 4 and 251 to 255 are cut, and thus the gradation value of 5 to 25 is used. In addition, regarding the gradation value for G and the gradation value for B, 0 to 255 is used.
In adjusting the white balance, as a method of adjusting the gradation voltage for each of RGB without adjustment of the gradation value for each of RGB, there exists a method described in Japanese Patent Laid-open No. Hei4-60583 gazette (hereinafter, referred to as a literature), for example.
FIG. 20
is a circuit diagram showing an electrical configuration of the signal electrode drive circuit
2
described in the foregoing literature.
The signal electrode drive circuit
2
includes: a serial/parallel conversion circuit
2
a
, decoders
2
b
1
, . . . ,
2
bn
, a color selection circuit
2
c
, and selection circuits
2
d
1
, . . . ,
2
dn
. The serial/parallel conversion circuit
2
a
receives the clock signal ck, the control signal Ct and the image signal V
4
, and outputs gradation values V
2
a
1
, . . . , V
2
an
for each of RGB of the image signal V
4
. The decoders
2
b
1
, . . . ,
2
bn
decode the gradation values V
2
a
1
, . . . , V
2
an
, and output selection signals S
2
b
1
, . . . , S
2
bn
corresponding to the gradation values V
2
a
1
, . . . , V
2
an
. The color selection circuit
2
c
selects voltages VA, VB, and VC for adjusting the gradation voltage for each of RGB, which are supplied to selected terminals A to C, for every horizontal line period of an image of the liquid crystal panel
1
(
FIG. 18
) based on a color selection signal CS, and outputs a voltage V
2
c
. The selection circuits
2
d
1
, . . . ,
2
dn
receive drive voltages V
1
, . . . , Vq generated by a voltage dividing resistor connected between the voltage V
2
c
and the central voltage Vs
1
, select drive voltages corresponding to the selection signals S
2
b
1
, . . . , S
2
bn
from the drive voltages V
1
, . . . , Vq, and output a sub-pixel data signal D
2
.
In the liquid crystal display device, the control circuit
4
outputs the clock signal ck, the control signal Ct, the image signal V
4
, the color selection signal CS and the central voltage Vs
1
. Another control circuit (not shown) outputs the color selection signal CS. The clock signal ck, the control signal Ct, the image signal V
4
for each of RGB and the central voltage Vs
1
are input to the signal electrode drive circuit
2
. Then, gradation voltages corresponding to the gradation value of the image signal V
4
for each of RGB are selected, and the sub-pixel data signal D
2
is generated, which is sent to each of data signal lines X
1
, . . . , Xn of the liquid crystal panel
1
.
In this case, the clock signal ck, the control signal Ct, and the image signal V
4
are input to the serial/parallel conversion circuit
2
a
, from which the gradation values V
2
a
1
, . . . , V
2
an
of the image signal V
4
for each of RGB are output. The gradation values V
2
a
1
, . . . , V
2
an
are input to the decoders
2
b
1
, . . . ,
2
bn
and decoded, from which selection signals S
2
b
1
, . . . , S
2
bn
are output. The voltages VA, VB, and VC supplied to selected terminals A, B, and C are selected for every horizontal line period of the image of the liquid crystal panel
1
in the color selection circuit
2
c
based on the color selection signal CS, and the voltage V
2
c
is output from the color selection circuit
2
c
. The drive voltages V
1
, . . . , Vq are input to the selection circuits
2
d
1
, . . . ,
2
dn
, and the drive voltage selected based on the selection signals S
2
b
1
, . . . , S
2
bn
is output as the sub-pixel data signal D
2
from the selection circuits
2
d
1
, . . . ,
2
dn.
In addition, the clock signal ck is input to the scanning electrode drive circuit
3
, the scanning signal V
3
is generated synchronously with the clock signal ck, and the scanning signal V
3
is sent to each of the scanning signal lines Y
1
, . . . , Ym of the liquid crystal panel
1
. In the liquid crystal panel
1
, the sub-pixel data signal D
2
is supplied to the sub-pixel region selected by the scanning signal V
3
, and color image corresponding to the sub-pixel data signal D
2
is displayed. Herein, voltages VA, VB, and VC are adjusted and input in accordance with the color of the color image on the liquid crystal panel
1
, and thus the white balance of the color image is adjusted.
However, in the foregoing conventional g
Kovalick Vincent E.
NEC LED Technologies, Ltd.
Shalwala Bipin
Young & Thompson
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