Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2002-08-06
2004-11-30
Mengistu, Amare (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S092000
Reexamination Certificate
active
06825822
ABSTRACT:
This application incorporates by reference of Taiwan application Serial No. 090119364, filed Aug. 9, 2001.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates in general to a display apparatus, and more particularly to a display apparatus with a time domain multiplex driving circuit.
2. Description of the Related Art
Featuring the favorable properties of thinness, lightness and generating low radiation, Liquid Crystal Display (LCDs) have been widely used in the world.
FIG. 1
shows a circuit diagram illustrating a conventional LCD panel. The display panel includes a plurality of pixels (P). The pixels are arranged in the form of a matrix on the display panel. The display panel includes an active matrix driving circuit for driving the pixels. The active matrix driving circuit includes a plurality of scan lines (S), a plurality of data lines (D), and a plurality of switching devices. The switching devices are set in the pixels for selectively transmitting the corresponding data signals to the pixels. The switching device can be a thin film transistor (TFT) such as an n-type field effect transistor (n-FET) or a p-type field effect transistor (p-FET). In
FIG. 1
, the switching device of each pixel includes a thin film transistor. The thin film transistor in each pixel includes a gate electrode, a first source/drain electrode, and a second source/drain electrode. The gate electrode of the thin film transistor is coupled to the corresponding scan line and the first source/drain electrode is coupled to the corresponding data line. Take the pixel P(m,n) for example. The pixel P(m,n) includes a thin film transistor M
1
. The gate electrode of the thin film transistor M
1
is coupled to the scan line S
m
, and the first source/drain electrode of the thin film transistor M
1
is coupled to the data line D
n
. Each scan line is perpendicular to each data line. Each pixel in the same pixel row is coupled to the same scan line and each pixel in the same pixel column is coupled to the same data line, as shown in FIG.
1
.
FIG. 2
shows the configuration of a conventional active matrix liquid crystal display. The conventional active matrix liquid crystal display includes a display panel
202
, an X board
214
, and a Y board
212
. The display panel
202
includes the pixels and the active matrix driving circuit, as shown in FIG.
1
. The X board
214
is coupled to a plurality of scan drivers
206
set in the tape carrier packages
210
. Each scan driver
206
is coupled to the X board
214
and the corresponding scan lines respectively. The Y board
212
is coupled to a plurality of data drivers
204
set in the tape carrier packages (TCP)
208
. Each data driver
204
is coupled to the Y board
212
and the corresponding data lines respectively. The X board
214
and the scan drivers
206
are used for enabling the corresponding scan lines through inputting a scan signal into the scan line. When the scan line is enabled, each pixel in the pixel row coupled to the scan line can be turned ON. The Y board
212
and the data drivers
204
are used for inputting the data signals to the corresponding pixels through the corresponding data lines when the pixels are turned ON.
The conventional active matrix liquid crystal display has the following disadvantages. First, a large number of data lines are needed. For example, an active matrix display panel has a resolution of 1024×768, that is, the active matrix display panel having 1024 pixel columns and each pixel column having 1024×3=3072 pixels. Therefore, the active matrix display panel must include 3072 data lines. The number of the data lines is large. Besides, since there are so many data lines are needed, the pitch between the adjacent data lines must be small. Second, each data line is coupled to the corresponding data driver through the outer lead of the tape carrier package. It is difficult and elaborate to connect all data lines to the corresponding outer leads of the tape carrier packages. Third, the aperture ratio of the display panel will be decreased since the number of the data lines is so large.
FIG. 3
shows the diagram of the conventional time domain multiplex driving circuit. In the conventional time domain multiplex driving circuit, every two adjacent pixels in the same pixel row are coupled to the same data line. These two pixels are set on the left and right sides of the data line respectively. The pixel set on the left side of the data line is called the left pixel (LP) and the pixel set on the right side of the data line is called the right pixel (RP). The switching devices of the pixels LP and RP are different. Take the pixels LP(m,n) and RP(m,n) as an example. These two pixels are coupled to both the same scan line S
m
and the same data line D
n
. The pixel LP(m,n) is set on the left side of the data line D
n
and the pixel RP(m,n) is set on the right side of the data line D
n
, as shown in FIG.
3
. The switching device of the pixel RP(m,n) includes a thin film transistor M
2
. The gate electrode of the thin film transistor M
2
is coupled to the scan line S
m
and the first source/drain electrode of the thin film transistor M
2
is coupled to the data line D
n
. The switching device of the pixel LP(m,n) is different from that of the pixel RP(m,n). The switching device of the pixel LP(m,n) includes two thin film transistors M
11
and M
12
. The gate electrode of the thin film transistor M
11
is coupled to the scan line S
m+1
and the first source/drain electrode of the thin film transistor M
11
is coupled to the data line D
n
. The gate electrode of the thin film transistor M
12
is coupled to the scan line S
m
and the first source/drain electrode of the thin film transistor M
12
is coupled to the second source/drain electrode of the thin film transistor M
11
, as shown in FIG.
3
.
FIG. 4
shows the timing chart of the scan signals of the scan lines S
m
, S
m+1
, and S
m+2
and the ON and OFF status of the corresponding pixels LP(m,n), RP(m,n), LP(m+1,n), and RP(m+1,n) shown in FIG.
3
. The method for driving display panel with the above-described time domain multiplex driving circuit is called a time domain multiplex driving method. When the time domain multiplex driving method is executed, each pixel row is driven in turn by the time domain multiplex driving circuit. The time domain multiplex driving method includes two scanning procedures. The first scanning procedure is to selectively turn on the left pixels of the pixel row by turning on two corresponding TFTs of each of the left pixels and then feeding the corresponding data signals into the respective left pixels. The second scanning procedure is to selectively turn on the right pixels of the pixel row by turning on one corresponding TFT of each right pixel and then feeding the corresponding data signals into the respective right pixels.
Take pixels LP(m,n) and RP(m,n) shown in
FIG. 3
as an example. In the time period T
1
, the scan line S
m
and S
m+1
are enabled. The thin film transistor M
11
and M
12
can be turned ON and a data signal can be inputted to the corresponding pixel LP(m,n) through the TFTs M
11
and M
12
. In the time period T
2
, only the scan line S
m
is enabled. The thin film transistor M
2
can be turned ON and a data signal can be inputted to the corresponding pixel RP(m,n) through the TFT M
2
.
In the time domain multiplex driving circuit, the above-described disadvantages of the conventional active matrix driving circuit can be improved. If the resolution of the display panel is 1024×768, for example, every two adjacent pixels in the same pixel row are coupled to one corresponding data line of the time domain multiplex driving circuit, and thus only 3072/2=1536 data lines are needed.
However, the conventional time domain multiplex driving circuit disclosed above has the following disadvantages. First, an equivalent resistor R
o
is produced between the first source/drain electrode and the second source/drain electrode when the thin film transist
Chei Mei Optoelectronics Corp.
Mengistu Amare
Patel Nitin
Rabin & Berdo P.C.
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