KR20070063737A - Apparatus and method for driving lcd - Google Patents

Abstract

An apparatus and a method for driving an LCD(Liquid Crystal Display) are provided to supply a desired black gamma reference voltage regardless of inner resistances due to surrounding circumference, thereby maintaining a desired black brightness, by controlling a level of black gamma reference voltage supplied to an LCD panel. A data driving unit(120) supplies black voltage to an LCD panel(110). A controller(220) controls a level of black gamma reference voltage, which is supplied to the data driving unit according to a newly set black brightness level. A gamma reference voltage generator(230) generates the black gamma reference voltage in proportion to resistance value varied by the controller. The gamma reference voltage generator includes a positive polarity gamma reference voltage generating part and a negative polarity gamma reference voltage generating part.

Description

Driving apparatus and driving method of liquid crystal display device {Apparatus and method for driving LCD}

1 is an equivalent circuit diagram of a pixel formed in a liquid crystal display device in general.

2 is a block diagram of a conventional liquid crystal display device.

3 is a circuit diagram of a gamma reference voltage generator of a conventional liquid crystal display device driving apparatus.

4 is a configuration diagram of a driving device of a liquid crystal display device according to an exemplary embodiment of the present invention.

5A is a circuit diagram of a gamma reference voltage generator according to an exemplary embodiment of the present invention.

5B is a circuit diagram of a gamma reference voltage generator according to another exemplary embodiment of the present invention.

6 is a characteristic diagram of a black gamma reference voltage supplied by the driving apparatus of the liquid crystal display device according to the present invention.

7 is a flowchart illustrating a method of driving a liquid crystal display device according to an exemplary embodiment of the present invention.

8 is a flowchart illustrating a method of driving a liquid crystal display device according to another exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100 and 200: driving device for liquid crystal display element 110: liquid crystal display panel

120: data driver 130: gate driver

150: backlight assembly 160: inverter

170: common voltage generator 180: gate driving voltage generator

190: timing controller 210: user input unit

220: control unit 230: gamma reference voltage generation unit

240: positive driving unit 250: negative driving unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to an apparatus and method for driving a liquid crystal display device capable of arbitrarily adjusting the level of a black gamma reference voltage serving as a level determination standard of a black voltage supplied to a liquid crystal display panel.

The liquid crystal display device displays an image by adjusting the light transmittance of the liquid crystal cells according to the video signal, and the active matrix type liquid crystal display device in which the switching elements are formed for each liquid crystal cell enables active control of the switching elements. This is advantageous for video implementation. As a switching device used in the active matrix liquid crystal display device, a thin film transistor (hereinafter, referred to as TFT) is mainly used as shown in FIG. 1.

Referring to FIG. 1, an active matrix type liquid crystal display device converts digital input data into an analog data voltage based on a gamma reference voltage and supplies it to the data line DL and simultaneously supplies scan pulses to the gate line GL. The liquid crystal cell Clc is charged.

The gate electrode of the TFT is connected to the gate line GL, the source electrode is connected to the data line DL, and the drain electrode of the TFT is connected to the pixel electrode of the liquid crystal cell Clc and one electrode of the storage capacitor Cst. Connected.

The common voltage Vcom is supplied to the common electrode of the liquid crystal cell Clc.

The storage capacitor Cst charges a data voltage applied from the data line DL when the TFT is turned on, thereby maintaining a constant voltage of the liquid crystal cell Clc.

When the scan pulse is applied to the gate line GL, the TFT is turned on to form a channel between the source electrode and the drain electrode so that the voltage on the data line DL is applied to the pixel electrode of the liquid crystal cell Clc. Supply. At this time, the liquid crystal molecules of the liquid crystal cell Clc modulate the incident light by changing the arrangement by the electric field between the pixel electrode and the common electrode.

A configuration of a conventional liquid crystal display device having pixels having such a structure will be described with reference to FIG. 2.

2 is a block diagram of a conventional liquid crystal display device.

Referring to FIG. 2, the liquid crystal display 100 according to the related art includes a thin film transistor for driving the liquid crystal cell Clc at the intersection of the data lines DL1 to DLm and the gate lines GL1 to GLn. TFT: a thin film transistor (110) having a thin film transistor (110), a data driver (120) for supplying data to the data lines (DL1 to DLm) of the liquid crystal display panel 110, the liquid crystal display panel 110 A gate driver 130 for supplying scan pulses to the gate lines GL1 to GLn of the gate lines, a gamma reference voltage generator 140 for generating a gamma reference voltage and supplying it to the data driver 120, and a liquid crystal display panel The backlight assembly 150 for irradiating light to the 110, the inverter 160 for applying an alternating voltage and current to the backlight assembly 160, and the common voltage Vcom are generated to generate the liquid crystal display panel 110. The common voltage generator 170 for supplying the common electrode of the liquid crystal cell Clc Controlling the gate driver voltage generator 180, the data driver 120, and the gate driver 130 to generate and supply the gate high voltage VGH and the gate low voltage VGL to the gate driver 130. A timing controller 190 is provided.

In the liquid crystal display panel 110, liquid crystal is injected between two glass substrates. The data lines DL1 to DLm and the gate lines GL1 to GLn are orthogonal to the lower glass substrate of the liquid crystal display panel 110. TFTs are formed at intersections of the data lines DL1 to DLm and the gate lines GL1 to GLn. The TFT supplies the data on the data lines DL1 to DLm to the liquid crystal cell Clc in response to the scan pulse. The gate electrodes of the TFTs are connected to the gate lines GL1 to GLn, and the source electrodes of the TFTs are connected to the data lines DL1 to DLm. The drain electrode of the TFT is connected to the pixel electrode of the liquid crystal cell Clc and the storage capacitor Cst.

The TFT is turned on in response to the scan pulse supplied to the gate terminal via the gate lines GL1 to GLn. When the TFT is turned on, video data on the data lines DL1 to DLm is supplied to the pixel electrode of the liquid crystal cell Clc.

The data driver 120 supplies data to the data lines DL1 to DLm in response to the data driving control signal DDC supplied from the timing controller 190, and digital video data supplied from the timing controller 190. After sampling and latching the RGB, the liquid crystal cell Clc of the liquid crystal display panel 110 is converted into an analog data voltage capable of expressing gray scale based on the gamma reference voltage supplied from the gamma reference voltage generator 140. Supply to the data lines DL1 to DLm.

The gate driver 130 sequentially generates scan pulses, that is, gate pulses, in response to the gate driving control signal GDC and the gate shift clock GSC supplied from the timing controller 190, thereby providing the gate lines GL1 to GLn. To feed. In this case, the gate driver 130 determines the high level voltage and the low level voltage of the scan pulse based on the gate high voltage VGH and the gate low voltage VGL supplied from the gate driving voltage generator 180.

The gamma reference voltage generator 140 receives a high potential power supply voltage VDD to generate a positive gamma reference voltage and a negative gamma reference voltage and output the same to the data driver 120.

The backlight assembly 150 is disposed on the rear surface of the liquid crystal display panel 110 and emits light by an AC voltage and a current supplied from the inverter 160 to irradiate light to each pixel of the liquid crystal display panel 110.

The inverter 160 converts the square wave signal generated therein into a triangular wave signal and compares the triangular wave signal with a DC power supply voltage (VCC) supplied from the system to generate a burst dimming signal proportional to the comparison result. . When a burst dimming signal determined according to an internal square wave signal is generated, a driving IC (not shown) for controlling the generation of AC voltage and current in the inverter 160 is supplied to the backlight assembly 150 according to the burst dimming signal. Control the generation of alternating voltage and current.

The common voltage generator 170 receives the high potential power voltage VDD to generate the common voltage Vcom and supplies the common voltage Vcom to the common electrodes of the liquid crystal cells Clc of each pixel of the liquid crystal display panel 110.

The gate driving voltage generator 180 receives the high potential power voltage VDD to generate the gate high voltage VGH and the gate low voltage VGL to supply the gate driver 130 to the gate driver 130. Here, the gate driving voltage generation unit 180 generates a gate high voltage VGH that is greater than or equal to the threshold voltage of the TFTs provided in each pixel of the liquid crystal display panel 110, and the gate low voltage that is less than or equal to the threshold voltage of the TFT. VGL). The gate high voltage VGH and the gate low voltage VGL generated in this way are used to determine the high level voltage and the low level voltage of the scan pulse generated by the gate driver 130, respectively.

The timing controller 190 supplies digital video data RGB, which is supplied from a digital video card (not shown), to the data driver 120, and also horizontal / vertical synchronization signals H and V according to the clock signal CLK. The data driving control signal DDC and the gate driving control signal GDC are generated by using the same and supplied to the data driver 120 and the gate driver 130, respectively. The data driving control signal DDC includes a source shift clock SSC, a source start pulse SSP, a polarity control signal POL, a source output enable signal SOE, and a gate driving control signal GDC. ) Includes a gate start pulse (GSP) and a gate output enable (GOE).

3 is a circuit diagram of a gamma reference voltage generator of a conventional liquid crystal display device driving apparatus.

Referring to FIG. 3, the conventional gamma reference voltage generator 140 includes the resistors R1-1 and R1-2 connected in series between the power supply voltage VDD and the ground, and the power supply voltage VDD. It is composed of resistors R2-1 and R2-2 connected in series between the grounds and connected in parallel with the resistors R1-1 and R1-2.

Here, the resistors R1-1 and R1-2 connected in series cause the positive black gamma reference voltage GMA_P to be generated through the output node N1, and the resistors R2-1 and R2-2 are generated. The negative black gamma reference voltage GMA_N is generated through the output node N2. In particular, since the resistors R1-1 and R1-2 have a constant resistance value, a constant positive black gamma reference voltage GMA_P is generated, and similarly, the resistors R2-1 and R2-2 also have a constant resistance value. Therefore, a constant negative black gamma reference voltage (GMA_N) is always generated.

However, due to the change in the high potential power voltage VDD and the resistance values of the resistors R1-1, R1-2, R2-1, and R2-2 due to the internal resistance component due to the ambient temperature environment, The negative black gamma reference voltage and the negative gamma reference voltage generated from the gamma reference voltage generator 140 have been changed. That is, since the black gamma reference voltage becomes a reference for determining the level of the black voltage supplied to the data lines DL1 to DLm, the black voltage is changed according to the change of the black gamma reference voltage, which results in a bad black luminance. Had a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to drive a liquid crystal display device capable of arbitrarily adjusting the level of the black gamma reference voltage, which is a level determination standard of the black voltage supplied to the liquid crystal display panel. An apparatus and method are provided.

An object of the present invention is to arbitrarily adjust the level of the black gamma reference voltage, which is the level determination standard of the black voltage supplied to the liquid crystal display panel, so that the desired black gamma reference voltage can be supplied regardless of the internal resistance component due to the ambient temperature environment. There is provided a driving device and method for a liquid crystal display device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a driving apparatus and method for a liquid crystal display device which can maintain a desired black luminance by supplying a desired black gamma reference voltage regardless of internal resistance components due to ambient temperature environment.

The present invention for achieving the above object, the data driving means for supplying a black voltage to the liquid crystal display panel; Control means for controlling the level of the black gamma reference voltage supplied to the data driving means as the black luminance level is newly set; And gamma reference voltage generating means for generating a black gamma reference voltage proportional to a resistance value varied by the control means and supplying the black gamma reference voltage to the data driving means.

The gamma reference voltage generating means includes: a positive gamma reference voltage generator for generating a positive black gamma reference voltage by receiving a high potential power supply voltage; And a negative gamma reference voltage generator configured to receive the high potential power voltage to generate a negative black gamma reference voltage.

The positive gamma reference voltage generator includes a plurality of first resistors and a first variable resistor connected in series between the high potential power voltage and ground, wherein the plurality of first resistors and the first variable resistor are connected to the negative. The polarity gamma reference voltage generator is connected in parallel.

The plurality of first resistors may have different resistance values.

The negative gamma reference voltage generator includes a plurality of second resistors and a second variable resistor connected in series between the high potential power voltage and ground, and the plurality of second resistors and the second variable resistor are connected in series. The plurality of first resistors and the first variable resistor are connected in parallel.

The plurality of second resistors may have different resistance values.

The first and second variable resistors may be simultaneously changed by the control means.

When the resistance values of the first and second variable resistors are changed high by the control means, the level of the positive black gamma reference voltage is lowered by the variable resistance value of the first variable resistor and at the same time the negative polarity. The level of the black gamma reference voltage is increased by the resistance value of the variable second variable resistor.

When the resistance values of the first and second variable resistors are changed low by the control means, the level of the positive black gamma reference voltage is increased by the resistance value of the variable first variable resistor and at the same time the negative black gamma The level of the reference voltage is lowered by the resistance value of the variable second variable resistor.

When the resistance values of the first and second variable resistors are changed high by the control means, the level of the positive black gamma reference voltage is increased by the resistance value of the variable first variable resistor and at the same time the negative black gamma The level of the reference voltage is lowered by the resistance value of the variable second variable resistor.

When the resistance values of the first and second variable resistors are changed low by the control means, the level of the positive black gamma reference voltage is lowered by the variable resistance value of the first variable resistor and at the same time the negative black. The level of the gamma reference voltage is increased by the resistance value of the variable second variable resistor.

The present invention provides a data driver for supplying a black voltage to a liquid crystal display panel; A positive gamma reference voltage generator for generating a positive black gamma reference voltage by supplying a high potential power voltage to the data driving means; And a negative gamma reference voltage generator configured to generate the negative black gamma reference voltage by supplying the high potential power voltage to the data driving means, wherein the positive gamma reference voltage generator is equal to the high potential power voltage. And a plurality of first resistors and a first variable resistor connected in series between the grounds, and the negative gamma reference voltage generator is connected in series between the high potential power voltage and the ground and the plurality of first resistors and the first resistors. And a plurality of second resistors and a second variable resistor connected in parallel with the variable resistor.

The present invention provides a display device comprising a first step of supplying a black voltage to a liquid crystal display panel by a data driver; A second step of varying a resistance value according to the newly set black luminance level when the black luminance level is newly set; And generating a black gamma reference voltage proportional to the variable resistance value and supplying the black gamma reference voltage to the data driver.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

4 is a configuration diagram of a driving device of a liquid crystal display device according to an exemplary embodiment of the present invention. only,

Referring to FIG. 4, the driving apparatus 200 of the liquid crystal display device of the present invention, as in FIG. 1, the liquid crystal display panel 110, the data driver 120, the gate driver 130, and the backlight assembly 150. The inverter 160 includes a common voltage generator 170, a gate driving voltage generator 180, and a timing controller 190.

In addition, the driving apparatus 200 of the liquid crystal display device of the present invention includes a user input unit 210 for inputting a user command for adjusting the black gamma reference voltage level, and a black according to the user command through the user input unit 210. The control unit 220 for controlling the level setting of the gamma reference voltage, and the positive black gamma reference voltage and the negative black gamma reference voltage corresponding to the first and second variable resistance values that are varied by the control unit 220, respectively. A gamma reference voltage generator 230 for generating and supplying the data driver 120 to the data driver 120 and a positive driver for varying the first variable resistance value of the gamma reference voltage generator 230 under the control of the controller 220. 240 and a negative driver 250 for varying the second variable resistance value of the gamma reference voltage generator 230 under the control of the controller 220.

The user input unit 210 is for inputting a black luminance level to be set by the user, and may be implemented to be exposed to the outside as a push button or a rotary button.

When the black luminance level to be newly set is input through the user input unit 210, the controller 220 generates the first and second gamma reference voltage generators 230 to generate a black gamma reference voltage proportional to the black luminance level. By varying the variable resistance value, controlling the driving of the positive driver 240 to vary the first variable resistance value corresponding to the positive black gamma reference voltage, and also to control the driving of the negative driver 250 The second variable resistor value corresponding to the negative black gamma reference voltage is varied. That is, the positive driver 240 varies the first variable resistance value of the gamma reference voltage generator 230 under the control of the controller 220, and the negative driver 250 controls the control of the controller 220. Accordingly, the second variable resistor value of the gamma reference voltage generator 230 is varied.

The gamma reference voltage generator 230 may vary the first variable resistor value corresponding to the positive black gamma reference voltage by the controller 220 and the second variable resistor value corresponding to the negative black gamma reference voltage. . Accordingly, the positive polarity black gamma reference voltage level and the negative polarity black gamma reference voltage level generated by the gamma reference voltage generator 230 vary according to the first and second variable resistance values that are varied by the controller 220, respectively. It is characterized by. A more detailed circuit configuration thereof will be described with reference to FIGS. 5A and 5B attached next.

5A is a circuit diagram of a gamma reference voltage generator according to an exemplary embodiment of the present invention.

Referring to FIG. 5A, the gamma reference voltage generator 230 is applied with the high potential power voltage VDD to generate the positive black gamma reference voltage BGMA_P. The positive gamma reference voltage generator PGR ( 231 and a negative gamma reference voltage generator (NGR) 232 for generating the negative black gamma reference voltage BGMA_N by receiving a high potential power voltage VDD.

The positive gamma reference voltage generator 231 includes a resistor R3-1, a variable resistor VR1, and a resistor R3-2 connected in series between the power supply voltage VDD and the ground in order. The positive gamma reference voltage generator 231 having such a configuration generates a positive black gamma reference voltage BGMA_P whose level is determined by the resistance values of the resistors R3-1, VR1, and R3-2. Supply to the driver 120. Here, the positive black gamma reference voltage BGMA_P is generated at the output node N3 located between the variable resistor VR1 and the resistor R3-2.

In addition, the resistance value of the variable resistor VR1 may be controlled by the controller 220 or may be manually changed by a user in the manufacturing stage of the product. Accordingly, when the resistance value of the variable resistor VR1 is increased, the level of the positive black gamma reference voltage BGMA_P generated at the output node N3 is lowered. On the contrary, when the resistance value of the variable resistor VR1 is decreased, the output is decreased. The level of the positive black gamma reference voltage BGMA_P generated at the node N3 is increased. At this time, the positive black gamma reference voltage (BGMA_P) level is a voltage distributed to the positive electrode (+) based on the common voltage (Vcom), as shown in Figure 6, the level is below the high potential power supply voltage (VDD) Only variable.

The negative gamma reference voltage generator 232 includes a resistor R4-1, a resistor R4-2, and a variable resistor VR2 connected in series between the power supply voltage VDD and the ground in order. The negative gamma reference voltage generator 232 having such a configuration generates a negative black gamma reference voltage BGMA_N whose level is determined by the resistance values of the resistors R4-1, VR2, and R4-2. Supply to the driver 120. Here, the negative black gamma reference voltage BGMA_N is generated at the output node N4 located between the resistors R4-1 and R4-2.

In addition, the resistance value of the variable resistor VR2 may be controlled by the controller 220 or may be manually changed by a user in the manufacturing stage of the product. Accordingly, when the resistance value of the variable resistor VR2 is increased, the level of the negative black gamma reference voltage BGMA_N generated at the output node N4 is increased. On the contrary, when the resistance value of the variable resistor VR2 is decreased, the output node is decreased. The level of the negative black gamma reference voltage BGMA_N generated at (N4) is lowered. At this time, the negative black gamma reference voltage (BGMA_N) level is a voltage distributed to the negative electrode (-) with respect to the common voltage (Vcom), as shown in Figure 6, its level is variable only above the electromotive voltage (GND). .

5B is a circuit diagram of a gamma reference voltage generator according to another exemplary embodiment of the present invention.

Referring to FIG. 5B, the positive gamma reference voltage generator 231 of the gamma reference voltage generator 230 may include a resistor R3-1 and a resistor R3- connected in series between the power supply voltage VDD and ground. 2) and variable resistor VR1. The positive gamma reference voltage generator 231 having such a configuration generates a positive black gamma reference voltage BGMA_P whose level is determined by the resistance values of the resistors R3-1, VR1, and R3-2. Supply to the driver 120. Here, the positive black gamma reference voltage BGMA_P is generated at the output node N5 located between the resistors R3-1 and R3-2.

Accordingly, when the resistance value of the variable resistor VR1 is increased, the level of the positive black gamma reference voltage BGMA_P generated at the output node N5 is increased. On the contrary, when the resistance value of the variable resistor VR1 is decreased, the output node is decreased. The level of the positive black gamma reference voltage BGMA_P generated at (N5) is lowered. At this time, the positive black gamma reference voltage (BGMA_P) level is variable only below the high potential power voltage (VDD) as shown in FIG.

The negative gamma reference voltage generator 232 of the gamma reference voltage generator 230 includes a resistor R4-1, a variable resistor VR2, and a resistor R4- connected in series between the power supply voltage VDD and ground. 2) is provided. The negative gamma reference voltage generator 232 having such a configuration generates a negative black gamma reference voltage BGMA_N whose level is determined by the resistance values of the resistors R4-1, VR2, and R4-2. Supply to the driver 120. Here, the negative black gamma reference voltage BGMA_N is generated at the output node N6 located between the variable resistor VR2 and the resistor R4-2.

In addition, the resistance value of the variable resistor VR2 may be controlled by the controller 220 or may be manually changed by a user in the manufacturing stage of the product. Accordingly, when the resistance value of the variable resistor VR2 is increased, the level of the negative black gamma reference voltage BGMA_N generated at the output node N6 is lowered. On the contrary, when the resistance value of the variable resistor VR2 is decreased, the output is reduced. The level of the negative black gamma reference voltage BGMA_N generated at the node N6 is increased. At this time, the negative black gamma reference voltage (BGMA_N) level is varied only above the electromotive voltage (GND), as shown in FIG.

FIG. 7 is a flowchart illustrating a method of driving a liquid crystal display device according to an exemplary embodiment of the present invention. When the circuit configuration of the gamma reference voltage generator 230 is implemented as shown in FIG. 5A, the level of the black gamma reference voltage is determined. It shows the process of arbitrarily adjusting.

Referring to FIG. 7, while the black voltage is being supplied to the liquid crystal display panel 110 (S701), the controller 220 determines whether a new black luminance level or a lower black luminance level is newly set than the current black luminance level. It is determined (S702). In this process, the user inputs a black luminance level higher or lower than the current black luminance level through the user input unit 210 to instruct the setting.

If the black luminance level higher than the current black luminance level is newly set, the controller 220 determines that the positive black gamma reference voltage BGMA_P and the negative black gamma reference voltage BGMA_N are proportional to the high black luminance level. The resistance value of the variable resistor VR1 of the positive gamma reference voltage generator 231 is changed to be higher than the current value so as to be supplied to the data driver 120, and at the same time, the variable resistor VR2 of the negative gamma reference voltage generator 232. The resistance value of V is changed higher than the present value (S703).

As the resistance values of the variable resistors VR1 and VR2 increase, the positive gamma reference voltage generator 231 generates a lower positive black gamma reference voltage BGMA_P in proportion to the increased resistance to generate a data driver. At the same time, the negative gamma reference voltage generator 232 generates an increased negative black gamma reference voltage BGMA_N in proportion to the increased resistance value and supplies the same to the data driver 120 (S704).

If it is determined that a new black luminance level lower than the current black luminance level is newly set, the controller 220 determines that the positive black gamma reference voltage BGMA_P and the negative black gamma reference voltage BGMA_N are proportional to the low black luminance level. The resistance value of the variable resistor VR1 of the positive gamma reference voltage generator 231 is lower than the current value so as to be supplied to the data driver 120, and at the same time, the variable resistor VR2 of the negative gamma reference voltage generator 232 is changed. The resistance value of V is changed lower than the present value (S705).

As the resistance values of the variable resistors VR1 and VR2 are lowered as described above, the positive gamma reference voltage generator 231 generates a higher positive black gamma reference voltage BGMA_P in proportion to the lower resistance value to generate the data driver ( At the same time, the negative gamma reference voltage generator 232 generates a lower negative black gamma reference voltage BGMA_N in proportion to the lowered resistance value and supplies it to the data driver 120 (S706).

FIG. 8 is a flowchart illustrating a method of driving a liquid crystal display device according to another embodiment of the present invention. When the circuit configuration of the gamma reference voltage generator 230 is implemented as shown in FIG. 5B, the level of the black gamma reference voltage is changed. It shows the process of arbitrarily adjusting.

Referring to FIG. 8, while the black voltage is being supplied to the liquid crystal display panel 110 (S801), the controller 220 determines whether a new black luminance level or a lower black luminance level is newly set than the current black luminance level. It is determined (S802). In this process, the user inputs a black luminance level higher or lower than the current black luminance level through the user input unit 210 to instruct the setting.

If the black luminance level higher than the current black luminance level is newly set, the controller 220 determines that the positive black gamma reference voltage BGMA_P and the negative black gamma reference voltage BGMA_N are proportional to the high black luminance level. The resistance value of the variable resistor VR1 of the positive gamma reference voltage generator 231 is changed to be higher than the current value so as to be supplied to the data driver 120, and at the same time, the variable resistor VR2 of the negative gamma reference voltage generator 232. The resistance value of V is changed higher than the present value (S803).

As the resistance values of the variable resistors VR1 and VR2 increase, the positive gamma reference voltage generator 231 generates an increased positive black gamma reference voltage BGMA_P in proportion to the increased resistance to generate a data driver. At the same time, the negative gamma reference voltage generator 232 generates a lower negative black gamma reference voltage BGMA_N in proportion to the increased resistance value and supplies it to the data driver 120 (S804).

If it is determined that a new black luminance level lower than the current black luminance level is newly set, the controller 220 determines that the positive black gamma reference voltage BGMA_P and the negative black gamma reference voltage BGMA_N are proportional to the low black luminance level. The resistance value of the variable resistor VR1 of the positive gamma reference voltage generator 231 is lower than the current value so as to be supplied to the data driver 120, and at the same time, the variable resistor VR2 of the negative gamma reference voltage generator 232 is changed. The resistance value of V is changed lower than the present value (S805).

As the resistance values of the variable resistors VR1 and VR2 are lowered as described above, the positive gamma reference voltage generator 231 generates a lower positive black gamma reference voltage BGMA_P in proportion to the lower resistance value, thereby driving the data driver. At the same time, the negative gamma reference voltage generator 232 generates a higher negative black gamma reference voltage BGMA_N in proportion to the lowered resistance value and supplies it to the data driver 120 (S806).

As described above, the present invention adjusts the level of the black gamma reference voltage by varying the resistance value of the variable resistor arbitrarily by the user, thereby supplying the desired black gamma reference voltage regardless of the internal resistance component due to the ambient temperature environment. It is possible to maintain the luminance condition, thereby improving the contrast ratio.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

Claims (25)

Data driving means for supplying a black voltage to the liquid crystal display panel; Control means for controlling the level of the black gamma reference voltage supplied to the data driving means as the black luminance level is newly set; And Gamma reference voltage generating means for generating a black gamma reference voltage proportional to a resistance value variable by the control means and supplying it to the data driving means. Driving device for a liquid crystal display device comprising a. The method of claim 1, The gamma reference voltage generating means, A positive gamma reference voltage generator for generating a positive black gamma reference voltage by receiving a high potential power voltage; And A negative gamma reference voltage generator for generating a negative black gamma reference voltage by receiving the high potential power voltage Driving device for a liquid crystal display device comprising a. The method of claim 2, The positive gamma reference voltage generator, A plurality of first resistors and a first variable resistor connected in series between the high potential power voltage and a ground; And the plurality of first resistors and the first variable resistor are connected in parallel with the negative gamma reference voltage generator. The method of claim 3, wherein And the plurality of first resistors have different resistance values. The method of claim 3, wherein The negative gamma reference voltage generator, A plurality of second resistors and a second variable resistor connected in series between the high potential power voltage and a ground; And the plurality of second resistors and the second variable resistor are connected in parallel with the plurality of first resistors and the first variable resistor connected in series. The method of claim 5, And the plurality of second resistors have different resistance values. The method of claim 5, And the first and second variable resistors are simultaneously varied by the control means. The method of claim 7, wherein When the resistance values of the first and second variable resistors are highly varied by the control means, the level of the positive black gamma reference voltage is lowered by the variable resistance value of the first variable resistor and at the same time the negative black. And a level of the gamma reference voltage is increased by a resistance value of the variable second variable resistor. The method of claim 7, wherein When the resistance values of the first and second variable resistors are changed low by the control means, the level of the positive black gamma reference voltage is increased by the resistance value of the variable first variable resistor and at the same time the negative black gamma And the level of the reference voltage is lowered by the resistance value of the variable second variable resistor. The method of claim 7, wherein When the resistance values of the first and second variable resistors are changed high by the control means, the level of the positive black gamma reference voltage is increased by the resistance value of the variable first variable resistor and at the same time the negative black And a level of the gamma reference voltage is lowered by a resistance value of the variable second variable resistor. The method of claim 7, wherein When the resistance values of the first and second variable resistors are changed low by the control means, the level of the positive black gamma reference voltage is lowered by the variable resistance value of the first variable resistor and at the same time the negative black. And a level of the gamma reference voltage is increased by a resistance value of the variable second variable resistor. A data driver for supplying a black voltage to the liquid crystal display panel; A positive gamma reference voltage generator for generating a positive black gamma reference voltage by supplying a high potential power voltage to the data driving means; And It is provided with a negative gamma reference voltage generator for generating a negative black gamma reference voltage supplied to the data driving means by receiving the high potential power voltage, The positive gamma reference voltage generator includes a plurality of first resistors and a first variable resistor connected in series between the high potential power voltage and ground, The negative gamma reference voltage generator includes a plurality of second resistors and a second variable resistor connected in series between the high potential power voltage and the ground and connected in parallel with the plurality of first resistors and the first variable resistor. A drive device for a liquid crystal display device, characterized in that it is provided. The method of claim 12, And the plurality of first resistors have different resistance values. The method of claim 13, And the plurality of second resistors have different resistance values. The method of claim 14, And the first and second variable resistors are simultaneously variable. The method of claim 15, When the resistance values of the first and second variable resistors are changed high, the level of the positive black gamma reference voltage is lowered by the variable resistance value of the first variable resistor and at the same time the level of the negative black gamma reference voltage. Is increased by the resistance value of the variable second variable resistor. The method of claim 15, When the resistance values of the first and second variable resistors are changed low, the level of the positive black gamma reference voltage is increased by the resistance value of the variable first variable resistor, and at the same time the level of the negative black gamma reference voltage is The driving device of the liquid crystal display device, characterized in that lowered by the resistance value of the variable second variable resistor. The method of claim 15, When the resistance values of the first and second variable resistors are changed high, the level of the positive black gamma reference voltage is increased by the resistance value of the variable first variable resistor, and at the same time the level of the negative black gamma reference voltage is The driving device of the liquid crystal display device, characterized in that lowered by the resistance value of the variable second variable resistor. The method of claim 15, When the resistance values of the first and second variable resistors are changed low, the level of the positive black gamma reference voltage is lowered by the variable resistance value of the first variable resistor and at the same time the level of the negative black gamma reference voltage. Is increased by the resistance value of the variable second variable resistor. A first step of the data driver supplying a black voltage to the liquid crystal display panel; A second step of varying a resistance value according to the newly set black luminance level when the black luminance level is newly set; And A third step of generating a black gamma reference voltage proportional to the variable resistance value and supplying the black gamma reference voltage to the data driver; Method of driving a liquid crystal display device comprising a. The method of claim 20, And in the second step, varying resistance values of the first and second variable resistors at the same time. The method of claim 21, In the third step, when the resistance values of the first and second variable resistors are changed high, the positive black gamma reference voltage level is lowered in proportion to the resistance value of the highly variable first variable resistor, and at the same time, the variable values are high. And driving the negative black gamma reference voltage level in proportion to the resistance of the second variable resistor. The method of claim 21, In the third step, when the resistance values of the first and second variable resistors are changed low, the positive black gamma reference voltage level is increased and simultaneously lowered in proportion to the resistance value of the first variable resistor. And driving the negative black gamma reference voltage level in proportion to the resistance of the second variable resistor. The method of claim 21, In the third step, when the resistance values of the first and second variable resistors are highly variable, the positive black gamma reference voltage level is increased in proportion to the resistance value of the first variable resistor, which is highly variable, and at the same time, the variable values are high. And a negative black gamma reference voltage level lowered in proportion to the resistance of the second variable resistor. The method of claim 21, In the third step, when the resistance values of the first and second variable resistors are changed low, the positive black gamma reference voltage level is lowered at the same time in proportion to the resistance value of the first variable resistor. And driving the negative black gamma reference voltage level in proportion to the resistance of the second variable resistor.

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