KR101220853B1 - Gate pulse supply apparatus for liquid crystal displa - Google Patents

Abstract

The present invention relates to a technique for improving the characteristics of the image quality by supplying different types of compensation gate pulses to the positive or negative data modulation voltage in the liquid crystal display device. The present invention includes a gate pulse supply unit for supplying different types of compensation gate pulses in response to modulation voltages of data voltages charged with positive or negative polarity; In supplying the gate pulse to the gate line of the liquid crystal panel, the gate driving circuit supplies different types of compensation gate pulses supplied from the gate pulse supply unit.

Description

GATE PULSE SUPPLY APPARATUS FOR LIQUID CRYSTAL DISPLA}

1 is a block diagram of a liquid crystal display device according to the prior art.

2 is a waveform diagram of a gate pulse generated by the prior art;

3 is a block diagram of a liquid crystal display device according to the present invention;

FIG. 4 is a detailed block diagram of the gate pulse driver of FIG. 3. FIG.

5A and 5B are waveform diagrams of gate pulses generated by the present invention.

*** Description of the symbols for the main parts of the drawings ***

31: System 32: Timing Controller

33: gate driving circuit 34: data driving circuit

35 liquid crystal panel 36 DC / DC converter

37 Inverter 38 Backlight Unit

39: gate pulse supply unit 39A: gate pulse generator

39B: Multiplexer

The present invention relates to a technique for supplying a gate pulse to a liquid crystal panel in a liquid crystal display device. In particular, when charging a data voltage of positive or negative polarity, different types of compensation gate pulses are provided to improve image quality characteristics. A gate pulse supply device for a liquid crystal display device is provided.

In general, the liquid crystal display (LCD) has been gradually expanded to office automation equipment, audio / video equipment, and the like due to features such as light weight, thinness, and low power consumption driving. The LCD displays a desired image on a screen by adjusting a transmission amount of a light beam according to an image signal applied to a plurality of control switches arranged in a matrix form.

Since the LCD is not a self-luminous display device, a light source such as a back light is required. There are two types of backlights for LCDs, a direct type method and a light guide plate method. In the direct type, a plurality of lamps are arranged in a plane, and a diffusion plate is installed between the lamp and the liquid crystal panel to maintain a constant space between the liquid crystal panel and the lamp. In addition, the light guide plate method is a lamp is installed on the outside of the flat plate, so that the light is incident from the lamp to the entire surface of the liquid crystal panel using a transparent light guide plate.

1 is a block diagram of a liquid crystal display device according to the prior art, as shown therein, a system 11; A liquid crystal panel 15 in which m × n liquid crystal cells Clc are arranged in a matrix type, m data lines D1 to Dm and n gate lines G1 to Gn cross each other, and a thin film transistor is formed at an intersection thereof. and; A gate driving circuit 13 for supplying a scan signal to the gate lines G1 to Gn under the control of the timing controller 12; A data driving circuit 14 for supplying data to data lines D1 to Dm of the liquid crystal panel 15 under the control of the timing controller 12; A timing controller 12 for controlling the driving of the gate driving circuit 13 and the data driving circuit 14 and outputting a brightness control voltage to the inverter 17; A DC / DC converter 16 for generating various driving voltages required by the liquid crystal panel 15; An inverter 17 for driving the backlight unit 18; The backlight unit 18 is configured to irradiate light onto the liquid crystal panel 15. The operation of the conventional liquid crystal display device configured as described above will be described below.

The liquid crystal panel 15 includes a plurality of liquid crystal cells Clc arranged in a matrix at the intersection of the data lines D1 to Dm and the gate lines G1 to Gn. Each TFT formed in the liquid crystal cell Clc transfers a data voltage input from the data lines D1 to Dm to the liquid crystal cell Clc in response to a scan signal supplied from the gate line G. In addition, a storage capacitor Cst is formed in each of the liquid crystal cells Clc, which is formed between the pixel electrode of the liquid crystal cell Clc and the front gate line, or between the pixel electrode and the common electrode of the liquid crystal cell Clc. It is formed to maintain a constant voltage of the liquid crystal cell (Clc).

The graphics processing circuit of the system 11 converts analog data into digital video data RGB and adjusts the resolution and color temperature of the digital video data RGB. The digital video data RGB and the vertical / horizontal synchronization signal and the clock signal output from the system 11 are supplied to the timing controller 12.

The timing controller 12 uses a gate control signal (GDC) and a data driving circuit 14 for controlling the gate driving circuit 13 by using a vertical / horizontal synchronization signal and a clock signal supplied from the system 11. It generates a data control signal (DDC) for controlling. In addition, the timing controller 12 samples the digital video data RGB input from the system 11, rearranges the digital video data RGB, and supplies the data to the data driving circuit 14.

The data driving circuit 14 converts the digital video data RGB into a data voltage (analog gamma compensation voltage) corresponding to the gray scale value in response to the data control signal DDC from the timing controller 12. The converted data voltage is supplied to the data lines D1 to Dm.

The gate driving circuit 13 sequentially supplies scan pulses (gate pulses) to the gate lines G1 to Gn in response to the gate control signal GDC from the timing controller 12 to supply data. Select the horizontal lines of (15).

The DC / DC converter 16 generates the high potential common voltage VDD voltage, VCOM voltage, gate high voltage VGH, and gate low voltage VGL using the VCC voltage from the system 11.

The inverter 17 converts the inverter DC input voltage Vinv from the system 11 into an AC voltage, and boosts the converted AC voltage to supply the tube current to the lamps of the backlight unit 18.

The backlight unit 18 irradiates light to the liquid crystal panel 15 with a surface light source by using an optical sheet such as a lamp, a light guide plate, a prism sheet, and an expansion sheet.

However, according to the data voltage supplied from the data driving circuit 14 to the data lines D1 to Dm, the positive charging or the negative charging is performed on the storage capacitor Cst on the liquid crystal panel 15. -) When charging, it is charged in a slightly distorted (modulated) form rather than in the original desired full square wave form.

Therefore, when the gate pulse is supplied to the gate lines G1 to Gn through the gate driving circuit 13 in the DC / DC converter 16, compensation for the form shown in FIG. 2 corresponding to the modulated data voltage is performed. Supply the gate pulse. That is, the “high” portion VGHM of the gate pulses supplies the compensation gate pulses in a modulated form as shown in FIG. 2.

However, in the conventional liquid crystal driving apparatus, the same type is used in supplying a gate pulse for compensating the data voltage (ΔV) of the modulated portion when + charging or-charging the storage capacitor Cst in response to the data voltage. Since the compensation gate pulse is modulated to be supplied, there is a defect that the image quality is deteriorated due to the lack of accurate compensation.

Accordingly, an object of the present invention is not to supply the same type of compensation gate pulses when charging a positive data voltage or a negative data voltage to a storage capacitor on a liquid crystal panel, but to provide different types of compensation gate pulses. It is to provide a gate pulse supply device for supplying.

According to an aspect of the present invention, there is provided a gate pulse supply unit configured to generate different types of compensation gate pulses in response to a modulation voltage of a data voltage charged with a positive polarity or a negative polarity; In supplying the gate pulse to the gate line of the liquid crystal panel, it characterized in that it comprises a gate driving circuit for supplying different types of compensation gate pulses supplied from the gate pulse supply unit.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram showing an embodiment of a gate pulse supply device of a liquid crystal display device according to the present invention, as shown therein; Liquid crystal panel 35 in which m × n liquid crystal cells Clc are arranged in a matrix type, m data lines D1 to Dm and n gate lines G1 to Gn intersect with each other, and a thin film transistor is formed at an intersection thereof. and; In supplying gate pulses (scan pulses) to the gate lines G1 to Gn under the control of the timing controller 32, different types of compensation gate pulses are supplied from the gate pulse supply part 39 to be described later. A gate driving circuit 33; A data driving circuit 34 for supplying data to the data lines D1 to Dm of the liquid crystal panel 35 under the control of the timing controller 32; A timing controller 32 for controlling the driving of the gate driving circuit 33 and the data driving circuit 34 and outputting a brightness control voltage to the inverter 37; A DC / DC converter 36 for generating various driving voltages required by the liquid crystal panel 35; An inverter 37 for driving the backlight unit 38; A backlight unit (38) for irradiating light onto the liquid crystal panel (35); The gate pulse supply unit 39 is configured to supply different types of compensation gate pulses to the gate driving circuit 33 according to the polarity signal input from the timing controller 32.

The gate voltage supply unit 39 includes: a gate pulse generator 39A for generating compensation gate pulses modulated in different forms corresponding to modulation voltages of data voltages charged with positive or negative polarity; The multiplexer 39B which selects compensation gate pulses modulated in different forms from the gate pulse generator 39A and supplies them to the gate driving circuit 33 according to the polarity signal input from the timing controller 32. ).

Referring to Figure 5 attached to the operation of the present invention configured as described above in detail as follows.

The liquid crystal panel 35 includes a plurality of liquid crystal cells Clc arranged in a matrix at the intersection of the data lines D1 to Dm and the gate lines G1 to Gn. Each TFT formed in the liquid crystal cell Clc transfers a data voltage input from the data lines D1 to Dm to the liquid crystal cell Clc in response to a scan signal supplied from the gate line G. In addition, a storage capacitor Cst is formed in each of the liquid crystal cells Clc, which is formed between the pixel electrode of the liquid crystal cell Clc and the front gate line, or between the pixel electrode and the common electrode of the liquid crystal cell Clc. It is formed to maintain a constant voltage of the liquid crystal cell (Clc).

The graphics processing circuit of the system 31 converts analog data into digital video data RGB and adjusts the resolution and color temperature of the digital video data RGB. The digital video data RGB and the vertical / horizontal synchronization signal and the clock signal output from the system 31 are supplied to the timing controller 32.

The timing controller 32 includes a gate control signal (GDC) and a data driving circuit 34 for controlling the gate driving circuit 33 by using a vertical / horizontal synchronization signal and a clock signal supplied from the system 31. It generates a data control signal (DDC) for controlling. In addition, the timing controller 32 samples the digital video data RGB input from the system 31 and rearranges the same to supply the data driving circuit 34.

The data driving circuit 34 converts the digital video data RGB into a data voltage (analog gamma compensation voltage) corresponding to the gray scale value in response to the data control signal DDC from the timing controller 32. The converted data voltage is supplied to the data lines D1 to Dm.

The gate driving circuit 33 sequentially supplies scan pulses (compensation gate pulses) to the gate lines G1 to Gn in response to the gate control signal GDC from the timing controller 32 to supply data. The horizontal lines of the liquid crystal panel 35 are selected.

The DC / DC converter 36 generates a high potential common voltage VDD voltage, VCOM voltage, gate high voltage VGH, and gate low voltage VGL using the VCC voltage from the system 31.

The inverter 37 converts the inverter DC input voltage Vinv from the system 31 into an AC voltage, and boosts the converted AC voltage to supply the tube current to the lamps of the backlight unit 38.

The backlight unit 38 irradiates light to the liquid crystal panel 35 with a surface light source by using an optical sheet such as a lamp, a light guide plate, a prism sheet, and an expansion sheet.

However, according to the data voltage supplied from the data driving circuit 34 to the data lines D1 to Dm, the positive charging or the negative charging is performed on the storage capacitor Cst on the liquid crystal panel 35. When charging, it is charged in a slightly distorted form, not in the form of the original desired complete square wave.

In view of this, in the present invention, the gate pulse supply unit 39 supplies the compensation gate pulse of the form corresponding to the modulated data voltage through the gate driving circuit 33 to the gate lines G1 to Gn. Instead of supplying a compensation gate pulse modulated in one form, a compensation gate pulse modulated in different forms is provided as shown in FIGS. 5A and 5B, which will be described in more detail with reference to FIG. 4. Is as follows.

That is, the gate pulse generator 39A may be configured to compensate for the gate pulses VGHM_1 and VGHM_2 in which the "high" portion VGHM of the gate pulses is modulated into different shapes as shown in FIG. 5A or 5B. Generate and print.

The multiplexer 39B selects the compensation gate pulse VGHM_1 or VGHM_2 according to the polarity signal POL input from the timing controller 32 and supplies it to the gate driving circuit 33.

However, since the positive charging and the negative charging are sequentially performed on the storage capacitor Cst in response to the data voltage, the multiplexer 39B performs the compensation gate pulse VGHM_1, in response to the polarity signal POL. VGHM_2 is sequentially selected or VGHM_2 and VGHM_1 are sequentially selected. The compensation gate pulses thus selected are supplied to the gate lines G1 to Gn through the gate driving circuit 33.

As described in detail above, the present invention does not supply the same type of compensation gate pulse when charging the positive data voltage or the negative data voltage to the storage capacitor on the liquid crystal panel, but for different types of compensation. By allowing the gate pulse to be selectively supplied, the charging imbalance with respect to the data voltage of the modulated portion is eliminated, thereby improving the image quality characteristics.

Claims (6)

A gate pulse supply unit for supplying different types of compensation gate pulses in response to modulation voltages of the data voltages charged positively or negatively; When supplying the gate pulse to the gate line of the liquid crystal panel, comprising a gate driving circuit for supplying different types of compensation gate pulse supplied from the gate pulse supply, A gate pulse supply device of a liquid crystal display device, wherein the compensation gate pulses having different types are pulses in which the "high" portions of the gate pulses are modulated in different forms. The method of claim 1, wherein the modulation voltage of the data voltage charged to the positive or negative polarity is a modulation voltage charged to the storage capacitor on the liquid crystal panel positive or negative according to the data voltage supplied to the data line of the liquid crystal panel. A gate pulse supply device for a liquid crystal display device, characterized in that. According to claim 1, wherein the gate pulse supply unit A gate pulse generator for generating compensation gate pulses that are modulated in different forms corresponding to modulation voltages of the data voltages charged positively or negatively; And a multiplexer which selects compensation gate pulses modulated in different forms from the gate pulse generator according to a polarity signal and supplies them to the gate driving circuit. 4. The gate pulse supply apparatus of claim 3, wherein the multiplexer is configured to sequentially select and output the compensation gate pulses modulated in different forms. 4. The gate pulse supply device of a liquid crystal display device according to claim 3, wherein the polarity signal is configured to be input from a timing controller. delete

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