Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1998-10-30
2002-08-06
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S099000, C345S100000
Reexamination Certificate
active
06429844
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a display apparatus employing a Liquid crystal panel, and more particularly to a data driving circuit for a liquid crystal panel that drives the liquid crystal panel with a digital image signal.
2. Description of the Prior Art
Recently, in image media, there has been a trend toward the use of digital, as opposed to analog, image signals. Digital image signals San be more easily compressed, providing a high resolution picture to a viewer. As a result, it becomes desirable for liquid crystal displays to be driven by analog as well as digital image signals. According to the driving circuit for the liquid crystal display panel has been configured to be adaptable for driving picture elements(or pixels) in a liquid crystal panel requiring an analog signal. As a result, in the liquid crystal display apparatus, analog-type data driving circuits now coexist with digital-type data driving circuits.
Since each digital-type data driving circuits process pixel data in parallel, they require high capacity of memories and use digital to analog D-A converters having a complex circuit configuration. As shown in
FIG. 1
, in order to drive data lines DL
1
to DL
2400
, the digital-type data driving circuit
20
includes first latches
22
connected to data buses DB1 to DB3, and second latches
24
, and a digital to analog(D-A) converter array
26
cascade-connected to the first latches
22
. The first and second latch arrays
22
and
24
include 2400 latches, respectively. Each of the latches has a length of 6 bits to receive 6 bit pixel data.
That is, as shown in
FIG. 2
, the latches included in the first and second latches
22
and
24
each include six 1-bit latches which each consist of two inverters INV
1
and INV
2
, an MOS transistor MN
1
and a capacitor C
1
. The 2400 latches in the first latch array
22
are sequentially driven in accordance with a logical value of an output signal of a shift register
28
to sample 6 bits of red(R), green(G) or blue(
3
) color pixel data from the data bus DB. The first latch array
22
temporarily stores R, G and S pixel data for one line, that is, 2400 pixel data. The 2400 latches included in the second latch array
24
respectively receive pixel data from the 2400 latches in the first latch array
22
simultaneously, and transfer the received pixel data to the D-A converter array
26
. The D-A converter array
26
converts the 2400 pixel data received from the second Latch array
24
into pixel signals, and applies the converted 2400 pixel signals to the 2400 data lines DL
1
to DL 2400 in the liquid crystal panel
10
, respectively. To this end, the D-A converter array
26
includes 2400 D-A converters. Each of these 2400 D-A converters receives 6 bit pixel data simultaneously and generates a pixel signal having voltage level that differs in accordance with a logical value of the 6 bit pixel data.
Meanwhile, in liquid crystal display devices, there has been a trend toward integrating the data driving circuit on the liquid crystal panel in order to reduce its bulk size. When integrating the data driving circuit on the liquid crystal panel, the size of liquid crystal panel becomes enlarged memories and complex D-A converters are typically large components. More specifically, since it is difficult to achieve a fine pitch by forming poly-silicon thin film transistors at a low temperature, the data driving circuit occupies an increasing wide area of the liquid crystal panel.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a data driving circuit for a liquid crystal pane having a simplified circuit configuration and being capable of integration on the liquid crystal panel.
In order to attain this and other objects of the invention, a data driving circuit for a liquid crystal panel includes data input lines for inputting video data in serial, a sampling cell array for sampling the video data inputted in serial from the data input lines, a serial digital to analog conversion cell array for converting the video data inputted in serial from each sampling cell in the sampling cell array into analog signals to apply the converted analog signals to each data lines in the liquid crystal panel, and sampling control means for supplying sequence pulses enabled exclusively and sequentially to each sampling cell included in the sampling cell array, thereby allowing the respective sampling cell to sample a predetermined bit number of data sequentially.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of example only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 5162786 (1992-11-01), Fukuda
patent: 5523772 (1996-06-01), Lee
patent: 5654735 (1997-08-01), Nakajima
patent: 5726676 (1998-03-01), Callahan, Jr. et al.
patent: 5796379 (1998-08-01), Enomoto et al.
patent: 5856816 (1999-01-01), Youn
Birch & Stewart Kolasch & Birch, LLP
Lewis David L.
LG Electronics Inc.
Shalwala Bipin
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