Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1998-11-24
2001-06-19
Liang, Regina (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S098000, C345S211000
Reexamination Certificate
active
06249270
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display device having the function of displaying intended display data as image data at selected ones of a plurality of pixels constituting a liquid crystal display panel, a drive circuit for the liquid crystal display device for supplying a power source voltage required for displaying the display data, and a method for driving the liquid crystal display device.
More particularly, the present invention relates to a liquid crystal display device comprising at least one gate driver for sequentially scanning a plurality of pixels through a plurality of first bus lines (generally called scan bus lines), and at least one data driver for supplying a drive voltage for displaying the display data to selected ones of the pixels on the first bus lines through a plurality of second bus lines (generally called data bus lines) crossing the first bus lines, a drive circuit for the liquid crystal display device for supplying the data driver with a power source voltage required for displaying the intended display data by activating the data driver, and a method for driving the liquid crystal display device for supplying the power source voltage to the data driver.
Generally, a portable personal computer such as a notebook-sized personal computer is used with a liquid crystal display device (usually abbreviated to LCD) as a thin and lightweight display device. Especially, in recent years, the notebook-sized personal computer or the like has rapidly prevailed, and opportunities for using various products associated with the notebook-sized personal computer or the like with a liquid crystal display device built therein have increased not only in workshops or offices, but also in various places other than these workshops or offices. Therefore, there is a tendency for high demand for various products to which the liquid crystal display device is applied, using a charge-discharge battery having a longer operation time, and smaller and lighter products to which the liquid crystal display device is applied, having a smaller charge-discharge battery. The current trend is to meet this demand and realize a liquid crystal display device which consumes less power by saving unnecessary power consumption as far as possible.
2. Description of the Related Art
In order to facilitate an understanding of the problems of the conventional liquid crystal display device used with the notebook-sized personal computer and the data driver of the liquid crystal display device, an explanation will be given of an example configuration of the conventional liquid crystal display device used with the notebook-sized personal computer and the operation of the data driver of the liquid crystal display device with reference to
FIGS. 1 and 2
as described later in “BRIEF DESCRIPTION OF THE DRAWINGS”.
In
FIG. 1
, a block diagram showing a configuration of a conventional liquid crystal display device is shown. In
FIG. 2
, a voltage waveform diagram showing the manner in which upper positioned data drivers and lower positioned data drivers, of the conventional type, are controlled is shown. The description that follows refers to a typical case in which the data drivers are divided into those including a first upper positioned data driver
600
-
1
to an N-th upper positioned data driver
600
-N (N: an arbitrary positive integer, hereinafter referred to simply as the upper positioned data drivers) connected to every other second bus line (for example, odd data bus lines)
60
a
, and those including a first lower positioned data driver
610
-
1
to an N-th lower positioned data driver
610
-N (hereinafter referred to simply as the lower positioned data drivers) connected to the remaining every other second bus line (even data bus lines, for example).
The liquid crystal display device shown in
FIG. 1
comprises a plurality of first bus lines
50
, a plurality of second bus lines
60
a
,
60
b
crossing the first bus lines
50
, and a plurality of pixels formed at the intersections of the first and second bus lines on a liquid crystal panel
4
which is configured of a m×n matrix (m, n: arbitrary positive integer). In other words, a plurality of liquid crystal cells constituting a plurality of pixels representing the minimum units of display data are arranged at the intersections of a plurality of first electrodes (row electrodes) X
1
to Xm making up the first bus lines
50
(scan bus lines) and a plurality of second electrodes (column electrodes) Y
1
to Yn constituting the second bus lines
60
a
,
60
b
(data bus lines).
Further, these pixels are connected to a plurality of transistor switching elements (not shown) made of TFTs (thin film transistors), respectively. These transistor switching elements in turn are connected to a plurality of the second electrodes Y
1
to Yn, respectively. Furthermore, control gates for controlling the on-off operation of the transistor switching elements are connected to the first electrodes X
1
to Xm, respectively. If it is assumed that the transistor switching elements are turned on and off by applying a predetermined voltage from a plurality of the first electrodes X
1
to Xm and a plurality of the second electrodes Y
1
to Yn, the same voltage is applied to the corresponding pixels through the transistor switching elements thus turned on, and an electric field is exerted on the liquid crystal in the pixels, and the orientation of the liquid crystal is changed. Thus the intended display data can be displayed as image data.
In
FIG. 1
, a horizontal arrangement of pixels, i.e. an arrangement of pixels along each scan bus line is called a line. The display data on the liquid crystal panel
4
is written for each scan bus line. This operation is repeated at the rate of 60 times per second, thereby presenting a flickerless image to the eyes of the user. Typically, a liquid crystal display device which has about 640 (n=640) pixels along the horizontal direction (along the scan bus lines) and about 480 (m=480) pixels along the vertical direction (along the data bus lines) of the liquid crystal panel
4
, finds wide application. Further, the color display requires additional pixels for R (red), G (green) and B (blue).
The liquid crystal display device further comprises a gate driver
5
for supplying each of the first electrodes X
1
to Xm with a gate driver control signal Sxco used for the on-off operation control of the transistor switching elements after being converted to an appropriate voltage level. The gate driver
5
causes all the pixels on the liquid crystal panel
4
to be sequentially scanned through the respective transistor switching elements. There are usually provided a plurality of gate drivers
5
including a plurality of ICs (integrated circuits) connected to the first electrodes X
1
to Xm, respectively. In
FIG. 1
, however, only one gate driver is shown for simplifying the explanation about the gate driver.
On the other hand, the liquid crystal display device comprises data drivers for producing the drive voltages OUT
1
, OUT
2
, . . . , OUT(n−
1
) and OUTn produced by converting the gradational voltage selected in accordance with the data signal of the display data into an appropriate voltage level and supplying them to a plurality of the second electrodes Y
1
to Yn. The data drivers usually include upper positioned data drivers
600
-
1
to
600
-N made of 4 to 5 ICs and lower positioned data drivers
610
-
1
to
610
-N made of 4 to 5 ICs (N=4 to 5).
Further, the liquid crystal display device shown in
FIG. 1
comprises a control signal generating circuit
300
for generating various control signals including a gate driver control signal Sxco and a data driver control signal Syco for controlling the operation of the gate driver
5
, the upper positioned data drivers
600
-
1
to
600
-N and the lower positioned data drivers
610
-
1
to
610
-N in accordance with an external input signal Sin.
Generally speaking, when a DC drive voltage is
Fujitsu Limited
Greer Burns & Crain Ltd.
Liang Regina
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