Liquid crystal display device having a timing controller and driving method thereof

A liquid crystal display device includes a liquid crystal display panel including a liquid crystal display panel provided a plurality of data lines; a data distributor distributing input data; a first and second memories equally storing data to be supplied to an odd-numbered data line among data distributed by the data distributor; a third and fourth memories equally storing data to be supplied to an even-numbered data line among data distributed by the data distributor; and a clock generator generating a divided clock reading and outputting a data stored at the first and second memories or the third and fourth memories.

This application claims the benefit of Korean Patent Application No. 10-2006-0050607 filed in Korea on Jun. 5, 2006, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relate to a liquid crystal display device, and more particularly to a method of driving a liquid crystal display device.

2. Description of the Related Art

Generally, a liquid crystal display (LCD) device controls light transmittance of liquid crystal cells in accordance with video signals to thereby display a picture. Among LCD devices, an active matrix LCD device has a switching device at each liquid crystal cell. The active matrix LCD device is advantageous for displaying a moving picture because of the control provided by the switching device. The switching device used for the active matrix LCD device may be, for example, a thin film transistor (TFT).

FIG. 1shows a circuit diagram of a pixel in a liquid crystal display device in accordance with the related art. Referring toFIG. 1, the active matrix LCD device includes gate lines GL and data lines DL crossing each other. Each crossing of one of the gate lines with one of the data lines define a pixel. A liquid crystal cell Clc is provided at each pixel. The active matrix LCD device converts a digital input data into an analog data voltage based on a gamma reference voltage. The analog voltage is supplied to one of the data lines DL. A scanning pulse is concurrently supplied to one of the gate lines GL to thereby charge the liquid crystal cell Clc.

A gate electrode of the TFT is connected to the gate line GL while a source electrode thereof is connected to the data line DL. Further, a drain electrode of the TFT is connected to a pixel electrode of the liquid crystal cell Clc and to one electrode of a storage capacitor Cst. A common electrode of the liquid crystal cell Clc is supplied with a common voltage Vcom. The storage capacitor Cst can be charged with the data voltage provided from the data line DL when the TFT is turned-on. Thus, the storage capacitor Cst maintains a substantially constant voltage at the liquid crystal cell Clc.

The TFT is turned on by the scanning pulse applied to the gate line GL to provide a channel between the source electrode and the drain electrode thereof. Thus, the TFT supplies a voltage from the data line DL to the pixel electrode of the liquid crystal cell Clc. An alignment direction of liquid crystal molecules from the liquid crystal cell is changed by an electric field between the pixel electrode and the common electrode, thereby modulating an incident light.

FIG. 2shows a schematic diagram of an LCD device in accordance with the related art. Referring toFIG. 2, the LCD device100includes an LCD panel110including a thin film transistor (TFT) that drives a liquid crystal cell Clc at a each crossing of one of data lines DL1to DLm and one of gate lines GL1to GLn, a data driver120supplying a data to the data lines DL1to DLm of the liquid crystal display panel110, and a gate driver130supplying a scanning pulse to the gate lines GL1to GLn of the liquid crystal display panel110. A gamma reference voltage generator140generates a gamma reference voltage to be supplied to the data driver120. A backlight assembly150irradiates light onto the liquid crystal display panel110. An inverter160inverts an alternating current to power the backlight assembly150. A common voltage generator170generates a common voltage Vcom to be supplied to the common electrode of the liquid crystal cell Clc of the liquid crystal display panel110. A gate driving voltage generator180generating a gate high voltage VGH and a gate low voltage VGL to be supplied to the gate driver130. A timing controller190controls the data driver120and the gate driver130.

The LCD panel110has a liquid crystal material injected between two glass substrates (not shown). The data lines DL1to DLm and the gate lines GL1to GLn perpendicularly cross each other on the lower glass substrate of the LCD panel110. A TFT is provided at each crossing of one of the data lines DL1to DLm with one of the gate lines GL1to GLn. The TFT supplies a data from the data lines DL1to DLm to the liquid crystal cell Clc in response to the scanning pulse.

The gate electrode of the TFT is connected to the gate lines GL1to GLn while the source electrode thereof is connected to the data line DL1to DLm. Further, the drain electrode of the TFT is connected to the pixel electrode of the liquid crystal cell Clc and to the storage capacitor Cst. The TFT is turned on by the scanning pulse applied through the gate lines GL1to GLn to the gate terminal thereof. Then, the TFT supplies a video data from the data line DL1to DLm to the pixel electrode of the liquid crystal cell Clc.

The gamma reference voltage generator140receives a high-level supply voltage VDD to generate a positive gamma reference voltage RV1and a negative gamma reference voltage RV2. The gamma reference voltage generator140provides the positive gamma reference voltage RV1and the negative gamma reference voltage RV2to the data driver120.

The data driver120samples and latches a digital data, such as a RGB digital video data or a RGB digital image data, from the timing controller190in response to a DDC signal from the timing controller190. Then, the data driver120converts the sampled digital data into an analog data voltage corresponding to a gray scale level at the liquid crystal cell Clc of the LCD panel110in accordance with the positive and negative gamma reference voltages RV1and RV2from the gamma reference voltage generator140. Then, the data driver120supplies the analog data voltage to the data lines DL1to DLm.

The gate driving voltage generator180is supplied with a high-level supply voltage VDD to generate a gate high voltage VGH and a gate low voltage VGL. The gate driving voltage generator180supplies the gate high voltage VGH and the gate low voltage VGL to the gate driver130. Herein, the gate high voltage VGH is larger than a threshold voltage of the TFT provided at each pixel of the LCD panel110and the gate low voltage VGL is lower than the threshold voltage of the TFT.

The gate driver130sequentially generates a gate pulse as a scanning pulse in response to a GDC signal and a gate shift clock GSC from the timing controller190. The gate driver130supplies the scanning pulse to the gate lines GL1to GLn. The gate driver130determines a high level voltage and a low level voltage of the scanning pulse in accordance with the gate high voltage VGH and the gate low voltage VGL from the gate driving voltage generator180.

The inverter160converts an internally generated square wave signal into a triangular wave signal, and then compares the generated triangular wave signal with a direct current (DC) voltage VCC from said system. Then, the inverter160generates a burst dimming signal proportional to a result of the comparison. Then, a driving integrated circuit (IC) (not shown) controls a generation of AC voltage and current supplied to the backlight assembly150in response to the burst dimming signal.

The backlight assembly150is provided at the rear side of the LCD panel110. The backlight assembly150is powered by the AC voltage from the inverter160. The backlight assembly150irradiates light onto the LCD panel110. The irradiated light from the backlight assembly150is incident onto each pixel of the LCD panel110including the liquid crystal cell Clc therein.

The common voltage generator170receives a high-level power voltage VDD to generate a common voltage Vcom. The common voltage generator170supplies the common voltage Vcom to the common electrode of the liquid crystal cell Clc provided at each pixel of the LCD panel110.

The timing controller190supplies a digital data, such as a digital video RGB data or a digital RGB image data, to the data driver120. The digital data may be outputted by an image processing scaler (not shown) in a system such as a TV set or a computer monitor, etc. The timing controller190also generates a data driving control (DCC) signal and a gate driving control (DGC) signal using horizontal/vertical synchronizing signals H and V in response to a clock signal CLK. The timing controller190supplies the DDC and the GDC signals to the data driver120and the gate driver130, respectively. The DDC signal may include a source shift clock (SSC), a source start pulse (SSP), a polarity control signal (POL), and a source output enable signal (SOE), etc. The GDC signal may include a gate start pulse (GSP) and a gate output enable signal (GOE), etc.

FIG. 3shows a schematic description of a timing controller in accordance with the related art. Referring toFIG. 3, the timing controller190includes a first memory part191, a second memory part192, a clock generator193, and a parallel-to-serial converter194. Herein, the first memory part191stores an input data to be supplied to an odd-numbered data line. The second memory part192stores an input data to be supplied to an even-numbered data line. The clock generator193generates clock signals for controlling reading and outputting stored data from one of the first memory part191and the second memory part192.

The clock generator193receives an input main clock (MAIN CLK) signal and generates four divided clock signals to control reading operations from the first and second memory parts191and192. The clock generator193alternatively supplies the four divided clocks signals to the first and second memory parts191and192. The four divided clocks signals control a reading operation of 72 bits of stored data from one of the first memory part191and the second memory part192.

The first memory part191stores an 18-bit input data at each divided clock cycle. Thus, the first memory part191can store 72 bits of input data during a period of four divided clocks from the clock generator193. Data stored in the first memory part191correspond to an odd-numbered data line.

Similarly, the second memory part192stores an 18-bit input data at each divided clock cycle. Thus, the second memory part192can store 72 bits of input data during a period of four divided clocks from the clock generator193. Data stored in the second memory part192correspond to an even-numbered data line.

The parallel-to-serial converter194converts the parallel data read from one of the first memory part191and the second memory part192into a serial data. The serial data from the parallel-to-serial converter194is outputted to the data driver120(shown inFIG. 2). For example, each of the 72 bits of stored data in the first memory part191is outputted to the parallel-to-serial converter194in parallel with a corresponding one of the 72 bits of stored data in the second memory part192.

In the related art LCD device, the timing controller190reads 72 bits of data into one of the first memory part191and the second memory part192during a period of four divided clock signals. Thus, the related art LCD device has a large blank section following a data enable signal.

SUMMARY OF THE INVENTION

Accordingly, embodiments of the present invention are directed to an LCD device and driving method thereof that substantially obviate one or more problems due to limitations and disadvantages of the related art.

An object of the present invention to provide an LCD device and a driving method thereof that substantially reduces an input data reading time.

Another object of the present invention to provide an LCD device and a driving method thereof that substantially reduces a blank section of a data enable signal inputted from a system.

Additional features and advantages of the invention will be set forth in the description of exemplary embodiments which follows, and in part will be apparent from the description of the exemplary embodiments, or may be learned by practice of the exemplary embodiments of the invention. These and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description of the exemplary embodiments and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a liquid crystal display device includes a liquid crystal display panel including a first plurality and a second plurality of data lines; first, second, third and fourth storage parts; a data distributor for evenly distributing first input data between a first stored data into the first storage part and a second stored data into the second storage part and for evenly distributing second input data between a third stored data into the third storage part and a fourth stored data into the fourth storage part; and a parallel-to-serial-converter simultaneously converting the first and second stored data from the first and second storage parts into a first serial data and outputting the first serial data during a first plurality of divided clock cycles and simultaneously converting the third and fourth stored data from the third and fourth storage parts into a second serial data and outputting the second serial data during a second plurality of divided clock cycles.

In another aspect, a liquid crystal display device includes a liquid crystal display panel including a first plurality and a second plurality of data lines; a parallel-to-serial converter outputting a first serial data during a first plurality of divided clock cycles and outputting a second serial data during a second plurality of divided clock cycles; and a data driver evenly distributing the first serial data to odd-numbered data lines from each of the first plurality and the second plurality of data lines.

In another aspect, a method is presented for driving a liquid crystal display device including a liquid crystal display panel with a plurality of data lines, and first, second, third, and fourth storage parts. The method includes dividing the plurality of data lines a first plurality and a second plurality of data lines; evenly distributing first input data between a first stored data into the first storage part and a second stored data into the second storage part and evenly distributing second input data between a third stored data into the third storage part and a fourth stored data into the fourth storage part; simultaneously converting the first and second stored data from the first and second storage parts into a first serial data and outputting the first serial data during a first plurality of divided clock cycles; and simultaneously converting the third and fourth stored data from the third and fourth storage parts into a second serial data and outputting the second serial data during a second plurality of divided clock cycles.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

FIG. 4shows a schematic diagram of an LCD device in accordance with an embodiment of the present invention. Referring toFIG. 4, an LCD device200includes a gate driver130, a gamma reference voltage generator140, a backlight assembly150, an inverter160, a common voltage generator170and a gate driving voltage generator180. The LCD device200further includes an LCD panel210, a timing controller220, and a data driver230.

The timing controller220evenly distributes and stores first input data, such as a digital RGB video data or a digital RGB image data, to be supplied to an odd-numbered data line. The stored first data are simultaneously read and outputted to the corresponding odd-numbered data line during two divided clock periods. Similarly, the timing controller220evenly distributes and stores second input data, such as a digital RGB video data or a digital RGB image data, to be supplied to an even-numbered data line. The stored second data are simultaneously read and outputted to the corresponding even-numbered data line during two divided clock periods.

The LCD panel210includes a plurality of data lines divided into a first and second line blocks. The data driver230evenly distributes the first data from the timing controller220to odd-numbered data lines of the first and second lines blocks, and evenly distributes the second data from the timing controller220to even-numbered data lines of the first and second lines blocks in accordance with a control of the timing controller220.

The LCD panel210is formed of two glass substrates (not shown) and a liquid crystal material (not shown) injected between two glass substrates. Data lines DL1to DLm and gate lines GL1to GLn perpendicularly cross each other on one of the glass substrates of the LCD panel210. Each crossing of the data lines DL1to DLm with the gate lines GL1to GLn is provided with a TFT and a liquid crystal cell Clc.

The plurality of data lines DL1to DLm are divided into a first and second line blocks. The data lines of the first line block are symmetrical with and simultaneously driven with the data lines of the second line block by the data driver230. For example, the first data lines of the first and second line blocks are simultaneously driven, and the last data lines of the first and second line blocks are simultaneously driven.

In an embodiment of the present invention, the timing controller220evenly distributes input RGB data to be supplied to odd-numbered data lines and stores the RGB data in at least two first storage parts. Then, the timing controller220simultaneously reads and out puts the stored RGB data from the at least two first storage parts to the data driver230during two divided clock periods. Similarly, the timing controller220evenly distributes RGB data to be supplied to even-numbered data lines and stores the RGB data in at least two second storage parts. Then, the timing controller220simultaneously reads and outputs the stored RGB data from the at least two second storage parts to the data driver230during two divided clock periods. In an embodiment, the stored RGB data are read in parallel from the storage parts. Thus, the timing controller220converts the parallel read data into a serial data to be outputted to the data driver230.

The data driver230evenly distributes data received from the timing controller220to odd-numbered data lines of the first and second line blocks, and evenly distributes data received from the timing controller220to even-numbered data lines of the first and second line blocks. For example, the data driver230divides 72 bits of data from the timing controller220into a first portion of 36 bits of data supplied to the odd-numbered data line of the first line block and a second portion of 36 bits of data supplied to the odd-numbered data lines of the second line block. As described above, the odd-numbered data lines of the first line block are symmetrical with the odd-numbered data lines of the second line block. Moreover, the first and second portions of 36-bit data are simultaneously supplied to the odd-numbered data lines of the first and second line blocks, respectively.

In another example, the data driver230divides 72 bits of data from the timing controller220into a first portion of 36 bits of data supplied to the even-numbered data line of the first line block and a second portion of 36 bits of data supplied to the even-numbered data lines of the second line block. As described above, the even-numbered data lines of the first line block are symmetrical with the even-numbered data lines of the second line block. Moreover, the first and second portions of 36-bit data are simultaneously supplied to the even-numbered data lines of the first and second line blocks, respectively.

FIG. 5shows a schematic description of a timing controller for the LCD device ofFIG. 4in accordance with an embodiment of the present invention. Referring toFIG. 5, the timing controller220includes a data distributor221, first and second memory parts222and223, third and fourth memory parts224and225, a clock generator226, a parallel-to-serial converter227. The data distributor221distributes input RGB data to the first to fourth memory parts222,223,224and225. Data to be supplied to an odd-numbered data line are evenly stored in the first and second memory parts222and223. Data to be supplied to an even-numbered data line are evenly stored in the third and fourth memory parts224and225.

The clock generator226receives an input main clock (MAIN CLK) signal and generates two divided clock signals to control reading operations from the first to fourth memory parts222to225. Specifically, the clock generator226generates a first divided clock signal for controlling reading and outputting of the data stored in the first and second memory parts222and223. The first divided clock signal is simultaneously supplied it to the first and second memory parts222and223. The clock generator226also generates a second divided clock signal for controlling reading and outputting of the data stored at the third and fourth memory parts224and225. The second divided clock signal is simultaneously supplied it to the third and fourth memory parts224and225. Moreover, the first and second divided clock signals are alternatively applied to first and second memory parts222and223and to the third and fourth memory parts224and225, respectively.

The data distributor221distributes input RGB data to be supplied to an odd-numbered data line to the first and second memory parts222and223. Alternatively, the data distributor221distributes input RGB data to be supplied to an even-numbered data line to the third and fourth memory parts224and225. For example, if 72 bits of input RGB data are to be provided to the odd-numbered data line, the data distributor221divides the 72 bits of input RGB data into a first 36-bit part and a second 36-bit part. Then, the data distributor221stores the first and second 36-bit parts at the first and second memory parts222and223, respectively. Similarly, if 72 bits of input RGB data are to be provided to the even-numbered line, the data distributor221divides the 72 bits of input RGB data into a third 36-bit part and a fourth 36-bit part. Then, the data distributor221stores the third and fourth 36-bit parts at the third and fourth memory parts224and225, respectively.

The first memory part222stores an 18-bit input data received from the data distributor221at each divided clock cycle. Thus, the first memory part222can store 36 bits of input data during a period of two divided clocks from the clock generator226. Data stored in the first memory part222correspond to an odd-numbered data line of the first line block.

The second memory part223stores an 18-bit input data received from the data distributor221at each divided clock cycle. Thus, the second memory part223can store 36 bits of input data during a period of two divided clocks from the clock generator226. Data stored in the second memory part223correspond to an odd-numbered data line of the second line block.

The parallel-to-serial converter227converts a parallel data simultaneously read from the first and second memory parts222and223into a first serial data, which is outputted to the data driver230(shown inFIG. 4). For example, 36 bits of stored data are outputted in parallel from the first and second memory parts222and223to the parallel-to-serial converter227at each divided clock cycle. Hence, 72 bits of stored data may be outputted in parallel from the first and second memory parts222and223to the parallel-to-serial converter227during a period of two divided clocks.

According to an embodiment of the present invention, 72 bits of input data to be supplied to the odd-numbered data line are divided into first and second 36-bit parts stored at the first and second memory parts222and223, respectively. The first and second 36-bit parts are simultaneously read from the first and second memory parts222and223, respectively. The 36-bit data outputted from the first memory part222are supplied to the odd-numbered data line of the first line block and, at the same time, the 36-bit data outputted from the second memory part223are supplied to the odd-numbered data line of the second line block. Thus, a data reading time is reduced in half in comparison to the related art.

The third memory part224stores an 18-bit input data received from the data distributor221at each divided clock cycle. Thus, the third memory part224can store 36 bits of input data during a period of two divided clocks from the clock generator226. Data stored in the third memory part224correspond to an even-numbered data line of the first line block.

The fourth memory part225stores an 18-bit input data received from the data distributor221at each divided clock cycle. Thus, the fourth memory part225can store 36 bits of input data during a period of two divided clocks from the clock generator226. Data stored in the fourth memory part225correspond to an even-numbered data line of the second line block.

The parallel-to-serial converter227converts a parallel data simultaneously read from the third and fourth memory parts224and225into a second serial data, which is outputted to the data driver230(shown inFIG. 4). For example, 36 bits of stored data are outputted in parallel from the third and fourth memory parts224and225to the parallel-to-serial converter227at each divided clock cycle. Hence, 72 bits of stored data may be outputted in parallel from the third and fourth memory parts224and225to the parallel-to-serial converter227during a period of two divided clocks.

According to an embodiment of the present invention, 72 bits of input data to be supplied to the even-numbered data line are divided into third and fourth 36-bit parts stored at the third and fourth memory parts224and225, respectively. The third and fourth 36-bit parts are simultaneously read from the third and fourth memory parts224and225, respectively. The 36-bit data outputted from the third memory part224are supplied to the even-numbered data line of the first line block and, at the same time, the 36-bit data outputted from the fourth memory part225are supplied to the even-numbered data line of the second line block. Thus, a data reading time is reduced in half in comparison to the related art.

The parallel-to-serial converter227converts a parallel data read from the first and second memory parts222and223, or from the third and fourth memory parts224and225into a serial data, which is outputted to the data driver230.

FIG. 6shows an exemplary timing diagram of an operation of an LCD device according to an embodiment of the present invention. Referring toFIG. 6, an externally provided data enable (DE) signal and a gate clock (GCLK) signal from the timing controller220are provided to the data driver230for supplying RGB data to the data line in accordance with a timing sequence. The RGB data may be 36 bits of data evenly stored at the first and second memory parts222and223.

During a first RT1period, the timing controller220reads R data stored at the first and second memory parts222and223and the data driver230supplies the read R data to the odd-numbered data line of the first and second line blocks. The data driver230pre-charges pixels positioned on the LCD panel110during a CT period following the first RT1period, and the timing controller220supplies a high-level data output enable (SOE) signal to the data driver230during an OT1period following the CT period. The data driver230performs a charge sharing function during the OT1period, and then supplies the read R data to the odd-numbered data line of the first and second line blocks during a PT1period.

During a second RT2period, the timing controller220reads G data stored at the first and second memory parts222and223. Then, the data driver230supplies the read G data to the odd-numbered data line of the first and second line blocks. The timing controller220supplies a high-level SOE signal to the data driver230during an OT2period following the RT2period and the PT1period. The data driver230performs a charge sharing function during the OT2period, and then supplies the read G data to the odd-numbered data line of the first and second line blocks during a PT2period.

During a third RT3period, the timing controller220reads B data stored at the first and second memory parts222and223. Next, the data driver230supplies the read B data to the odd-numbered data line of the first and second line blocks during a PT3period. Herein, the timing controller220supplies a high-level data SOE signal to the data driver230during an OT3period following the RT3period and the PT2period. The data driver230performs a charge sharing function during the OT3period, and then supplies the read B data to the odd-numbered data line of the first and second line blocks during the PT3period.

The timing diagram ofFIG. 6can also be applied for reading 36 bits of RGB data evenly stored at the third and fourth memory parts224and225. Then, the LCD device200supplies the read RGB data to the even-numbered data lines of the first and second line blocks.

As shown inFIG. 6, data is provided during a data section of the DE signal and no data is provided during a blank section of the DE signal. Accordingly, the present invention reduces reading sections RT1, RT2and RT3of RGB data, so that it becomes possible to reduce a blank section of the data enable signal DE.

In an embodiment of the present invention, a timing controller evenly distributes input RGB data to be supplied to an odd-numbered data line and stores the RGB data in at least two first storage parts. Then, the timing controller simultaneously reads and outputs the stored RGB data from the at least two first storage parts to a data driver during two divided clock periods. Similarly, the timing controller evenly distributes RGB data to be supplied to an even-numbered data line and stores the RGB data in at least two second storage parts. Then, the timing controller simultaneously reads and outputs the stored RGB data from the at least two second storage parts to the data driver230during two divided clock periods. Moreover, the stored RGB data are read in parallel from the storage parts. Accordingly, a blank section of a data enable signal is substantially reduced.

It will be apparent to those skilled in the art that various modifications and variations can be made in embodiments of the present invention. Thus, it is intended that embodiments of the present invention cover the modifications and variations of the embodiments described herein provided they come within the scope of the appended claims and their equivalents.