Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-11-19
2004-04-27
Awad, Amr (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S089000, C345S690000, C349S034000
Reexamination Certificate
active
06727874
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving circuit and a driving method of a color liquid crystal display, and a color liquid crystal display device; and more particularly to the driving circuit of the color liquid crystal display adapted to drive the color liquid crystal display based on digital video data to which a gamma correction has been made, the display device having such the driving circuit of the color liquid crystal display, and the method for driving the color liquid crystal display.
The present application claims priority of Japanese Patent Application No.2000-353427 filed on Nov. 20, 2000, which is hereby incorporated by reference.
2. Description of the Related Art
FIG. 17
is a schematic block diagram showing an example of configurations of a conventional driving circuit of a color liquid crystal display
1
disclosed in Japanese Laid-open Patent Application No. 2001-134242 published on May 18, 2001 later than the filing date of Japanese Patent Application No. 2000-353427 corresponding to the present application (Therefore, Japanese Laid-open Patent Application No. 2001-134242 has not a qualification as a prior art reference.)
The disclosed color liquid crystal display
1
is of a type of color liquid crystal display that is driven by an active-matrix driving method and that uses, for example, a TFT (Thin Film Transistor) as a switching element. Pixels are disposed in a region surrounded by a plurality of scanning electrodes (gate lines) mounted at predetermined intervals in a row direction and by a plurality of data electrodes (source lines) mounted at predetermined intervals in a column direction. Each of the pixels has a liquid crystal cell being equivalently a capacitive load, the TFT used to drive a corresponding liquid crystal cell and a capacitor used to accumulate a data charge during one vertical sync period. By applying a data red signal, data green signal, and data blue signal to be produced, based on red data D
R
, green data D
G
, and blue data D
B
being digital video data, to the data electrode and, at the same time, by applying scanning signals to be produced based on a horizontal sync signal and a vertical sync signal to the scanning electrode, a color character, color image or a like is displayed (though not shown in FIG.
17
). Moreover, the disclosed color liquid crystal display
1
operates in a so-called “normally black mode” in which transmittance or luminance of light obtained when an off-driving voltage is applied is lower than those obtained when the on-driving voltage is applied.
As shown in
FIG. 17
, the disclosed driving circuit of the color liquid crystal display
1
chiefly includes a control circuit
2
, a gray scale power circuit
3
, a data electrode driving circuit
4
, and a scanning electrode driving circuit
5
.
The control circuit
2
is made up of, for example, ASICs (Application Specific Integrated Circuits) and is adapted to feed 8 bits of red data D
R
, 8 bits of green data D
G
, and 8 bits of blue data D
B
supplied from an outside to the data electrode driving circuit
4
and, at the same time, to produce a horizontal scanning pulse P
H
, a vertical scanning pulse P
V
, and a polarity reversed pulse POL used to drive the color liquid crystal display
1
with alternating current, based on the horizontal sync signal and vertical sync signal, and to feed these pulses to the data electrode driving circuit
4
and the scanning electrode driving circuit
5
. Moreover, the control circuit
2
feeds a red gray scale voltage data D
GR
, a green gray scale voltage data D
GG
, and a blue gray scale voltage data D
GB
obtained by making an individual and separate gamma correction to each of the red data D
R
, green data D
G
, and blue data D
B
to provide gray scales, to the gray scale power circuit
3
. Moreover, the gamma correction employed in the embodiment includes one gamma correction (hereinafter referred to as a first gamma correction) in which the correction is made to arbitrarily provide a characteristic of luminance required in reproduced images to luminance of input images and another gamma correction (hereinafter referred to as a second gamma correction) that is made to match an “applied voltage−transmittance” characteristic (hereinafter as a V−T characteristic) for each of the red, green, and blue colors used in the color liquid crystal display
1
.
The gray scale power circuit
3
, as shown in
FIG. 18
, includes digital/analog converters (DACs)
11
1
to
11
3
and voltage followers
12
1
to
12
54
. The DAC
11
1
converts the red gray scale data DGR fed from the control circuit
2
into analog red gray scale voltages V
R0
to V
R17
and feeds them to the voltage followers
12
1
to
12
18
, respectively. Similarly, the DAC
11
2
converts the green gray scale data D
GG
fed from the control circuit
2
into analog green gray scale voltages V
G0
to V
G17
and feeds them to the voltage followers
12
19
to
12
36
, respectively. The DAC
11
3
converts the blue gray scale data D
GB
fed from the control circuit
2
into analog green gray scale voltages V
B0
to V
B17
and feeds them to the voltage followers
12
37
to
12
54
, respectively. The voltage followers
12
1
to
12
54
feed the red gray scale voltages V
R0
to V
R17
, the corresponding green gray scale voltages V
G0
to V
G17
, and the blue gray scale voltages V
B0
to V
B17
, which are all used for making the gamma correction, as they are, to the data electrode driving circuit
4
.
The data electrode driving circuit
4
is made up of k pieces (“k” being a natural number) of data electrode driving sections
4
1
to
4
k
. Each of the data electrode driving sections
4
1
to
4
k
makes the gamma correction, based on red gray scale voltages V
R0
to V
R17
, green gray scale voltages V
G0
to V
G17
, and blue gray scale voltages V
B0
to V
B17
fed from the gray scale power circuit
3
, to the red data D
R
, green data D
G
, and blue data D
B
each corresponding to each of data electrodes mounted in the color liquid crystal display
1
, out of the red data D
R
, the green data D
G
, and the blue data D
B
fed from the control circuit
2
, in order to provide gray scales, and converts the gamma-corrected data into 384 pieces of analog data signals and then outputs them. For example, when the color liquid crystal display
1
is of a type of SXGA (Super Extended Graphics Array) which provides 1280×1024 pixel resolution, since one pixel is made up of three dot pixels including a red (R) dot pixel, a green (G) dot pixel, and a blue (B) dot pixel, the number of dot pixels becomes 3840×1024. Therefore, in the example, the data electrode driving circuit
4
is made up of ten pieces of data electrode driving sections
4
1
to
4
10
(3840 pieces of pixels÷384 pieces of data signals). Since all of the data electrode driving sections
4
1
to
4
10
have the same configurations except that each of their components and each of input and output signals have a different subscript, a description of only the data electrode driving section
4
1
will be provided below.
FIG. 19
is a schematic block diagram showing an example of configurations of the data electrode driving section
4
1
. As shown in
FIG. 19
, the data electrode driving section
4
1
chiefly includes multiplexers (MPXs)
13
1
to
13
3
, DACs
14
1
to
14
3
(of an 8 bit-data conversion type), and voltage followers
15
1
to
15
384
. The MPX
13
1
switches a set of red gray scale voltages V
R0
to V
R8
or a set of red gray scale voltages V
R9
to V
R17
, out of red gray scale voltages V
R0
to V
R17
fed from the gray scale power circuit
3
, based on a polarity reversed pulse POL fed from the control circuit
2
and feeds the switched voltages to the DAC
14
1
. Similarly, the MPX
13
2
switches a set of red gray scale voltages V
G0
to V
G8
or a set of green gray scale voltages V
G9
to V
G17
, out of green gray scale voltages V
G0
to V
G17
fed from the gray scale power circuit
3
, based on the polarity reve
Awad Amr
Foley & Lardner
NEC LCD Technologies Ltd.
LandOfFree
Driving circuit and driving method of color liquid crystal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Driving circuit and driving method of color liquid crystal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Driving circuit and driving method of color liquid crystal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3214590