Liquid crystal display and driving method thereof

Computer graphics processing and selective visual display system – Display driving control circuitry – Display power source

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C345S211000, C345S212000, C345S087000

Reexamination Certificate

active

06525720

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a liquid crystal display, and more particularly to a liquid crystal display device and a driving method thereof that are adapted to display a certain information to a user when no signal is input after a power was applied to the liquid crystal display device.
2. Description of the Related Art
Generally, a liquid crystal display (LCD) has been employed a notebook PC, an office automation equipment and an audio/video equipment, etc. owing to advantages of a small dimension, a thin thickness and a low power consumption. In particular, an active matrix liquid crystal display using thin film transistors (TFT's) as switching devices is suitable for displaying a dynamic image.
FIG. 1
is a block diagram showing a configuration of the conventional LCD. In
FIG. 1
, an interface part
10
receives a data (RGB data) and control signals (e.g., an input clock, a horizontal synchronizing signal, a vertical synchronizing signal and a data enable signal) inputted from a driving system such as a personal computer (not shown) to apply them to a timing controller
12
. A low voltage differential signal (LVDS) interface and a transistor transistor logic (TTL) interface are largely used for a data and control signal transmission to the driving system. Such interfaces may be integrated into a single chip along with the timing controller
12
by collecting each function of them.
The timing controller
12
takes advantages of a control signal inputted via the interface
10
to produce control signals for driving a data driver
18
consisting of a plurality of drive IC's (not shown) and a gate driver
20
consisting of a plurality of gate drive IC's (not shown). Also, the timing controller
12
transfers a data inputted from the interface
10
to the data driver
18
. A reference voltage generator
16
generates reference voltages of a digital to analog converter (DAC) used in the data driver
18
, which are established by a producer on a basis of a transmissivity to voltage characteristic of the panel. The data driver
18
selects reference voltages of an input data in response to control signals from the timing controller
12
and applies the selected reference voltage to the liquid crystal display panel
2
, thereby controlling a rotation angle of the liquid crystal. The gate driver
20
makes an on/off control of the thin film transistors (TFT's) arranged on the liquid crystal panel
22
in response to the control signals inputted from the timing controller
12
. Also, the gate driver
20
allows the analog image signals from the data driver
18
to be applied to each pixel connected to each TFT. A power voltage generator
14
supplies an operation voltage to each element, and generates a common electrode voltage and applies it to the liquid crystal panel
22
.
FIG. 2
is a schematic block diagram showing a configuration of the timing controller in FIG.
1
. In
FIG. 2
, the timing controller
12
includes a control signal generator
22
and a data signal generator
24
. The timing controller
12
receives a horizontal synchronizing signal, a vertical synchronizing signal, a data enable signal, a clock and a data (R,G,B). The vertical synchronizing signal represents a time required for displaying one frame field. The horizontal synchronizing signal represents a time required for displaying one line of the field. Thus, the horizontal synchronizing signal includes pulses corresponding to the number of pixels included in one line. The data enable signal represents a time supplying the pixel with a data.
The data signal generator
24
rearranges a data so that desired bits of data (R,G,B) inputted from the interface
10
can be supplied to the data driver
18
. The control signal generator
22
receives the horizontal synchronizing signal, the vertical synchronizing signal, the data enable signal and the clock signal to generate various control signals and apply them to the data driver
18
and the gate driver
20
. The control signals required for the data driver
18
and the gate driver
20
will be described below. Herein, the control signals used commonly other than the control signals required specially will be described.
The control signals required for the data driver
18
include source sampling clock (SSC), source output enable (SOE), source start pulse (SSP) and liquid crystal polarity reverse (POL) signals, etc. The SSC signal is used as a sampling clock for latching a data in the data driver
18
, and which determines a drive frequency of the data drive IC. The SOE signal transfer a data latched by the SSC signal to the liquid crystal panel. The SSP signal is a signal notifying a latch or sampling initiation of the data during one horizontal synchronous period. The POL signal is a signal notifying the positive or negative polarity of the liquid crystal for the purpose of making an inversion driving of the liquid crystal.
The control signals required for the gate driver
20
include gate shift clock (GSC), gate output enable (GOE) and gate start pulse (GSP) signals, etc. The GSC signal is a signal determining a time when a gate of the TFT is turned on or off. The GOE signal is a signal controlling an output of the gate driver
20
. The GSP signal is a signal notifying a first drive line of the field in one vertical synchronizing signal.
The control signals inputted to the data driver
18
and the gate driver
20
as mentioned above are generated by the control signals inputted from the interface
10
. Thus, if no control signal is input from the interface
10
, then the timing controller
12
fails to generate a control signal. In other words, if any control signals are not inputted from the interface
10
in a power-on state, then the liquid crystal panel
2
does not display a picture. If a state in which the liquid crystal panel
2
does not display a picture upon power-on is sustained, then the liquid crystal is deteriorated to leave traces. Such deteriorated traces is viewed even when the LCD make a normal display to cause a trouble of the LCD.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a liquid crystal display and a driving method thereof that is adapted to display a certain information to a user when no signal is input after a power was applied.
In order to achieve these and other objects of the invention, a liquid crystal display device according to one aspect of the present invention includes a liquid crystal display panel having pixel electrodes arranged in a matrix type; a timing controller for generating and outputting control signals for driving the liquid crystal display panel in response to a timing synchronizing signal inputted from the exterior thereof and for re-arranging and outputting an input data; a drive circuit connected between the liquid crystal display panel and the timing controller to display a data inputted from the timing controller on the liquid crystal display panel in response to the control signal; an oscillator for generating a pre-synchronizing signal having a desired frequency to apply the same to the timing controller; a signal presence determiner for comparing the timing synchronizing signal with the pre-synchronizing signal to generate a determining signal indicating an input existence of the timing synchronizing signal; a control signal generator for generating a control signal on the basis of the pre-synchronizing signal in response to a determining signal indicating no input of the timing synchronizing signal; and a data storage device for storing a certain picture data and outputting the picture data to the drive circuit in response to the determining signal indicating no input of the timing synchronizing signal.
A liquid crystal display device according to another aspect of the present invention includes a liquid crystal display panel having pixel electrodes arranged in a matrix type; an oscillator for generating a reference clock having the same frequency as a horizontal synchronizing signal and a

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Liquid crystal display and driving method thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Liquid crystal display and driving method thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid crystal display and driving method thereof will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-3123097

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.