KR20070063678A - Liquid crystal display and driving method the same - Google Patents

Abstract

A liquid crystal display and a driving method thereof are provided to reduce power consumption in the liquid crystal display by eliminating a DC/DC converter through a power supply unit using an inverter driving voltage for a light source. A liquid crystal display includes a first power supplying unit(100) for supplying a first driving voltage, and a second power supplying unit(110) for supplying a common voltage, a gate-on voltage and a gate-off voltage by using a second driving voltage inputted externally. The second power supplying unit includes a pulse modulation unit, a gate-on voltage generating unit and a gate-off voltage generating unit. The gate-on voltage generating unit has a first boosting circuit for raising the second driving voltage and the voltage input from the pulse modulation unit.

Description

Liquid crystal display and its driving method {LIQUID CRYSTAL DISPLAY AND DRIVING METHOD THE SAME}

1 is a block diagram illustrating a power supply unit of a conventional liquid crystal display device.

2 is a block diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 3 is a diagram illustrating a power supply unit of the liquid crystal display shown in FIG. 2.

4 is a diagram illustrating a pulse modulator of the power supply unit illustrated in FIG. 3.

FIG. 5 is a diagram illustrating a gate-on voltage generator shown in FIG. 3.

6 is a diagram illustrating the gate-off voltage generator shown in FIG. 3.

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

<Brief Description of Drawings>

10: power supply unit 12: DC / DC converter

100: first power supply unit 110: second power supply unit

120: timing controller 130: common voltage generator

140: pulse modulator 150: gate off voltage generator

151: second pumping circuit 160: gate-on voltage generator

161: first pumping circuit 170: gate driver

180: data driver 200: liquid crystal panel

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a driving method thereof capable of reducing power consumption.

In general, a liquid crystal display device displays an image by adjusting light transmittance of liquid crystal cells according to a video signal.

1 is a block diagram illustrating a power supply unit of a conventional liquid crystal display device.

Conventional liquid crystal display devices include a video card for converting analog data into digital image data, a data driver for supplying image data to data lines of the liquid crystal panel, a gate driver for sequentially driving gate lines of the liquid crystal panel; And a timing controller for controlling the data driver and the gate driver, and a power supply unit for generating a voltage for driving the gate driver, the data driver, the timing controller, and the like.

The video card converts an analog input video signal into a digital image data signal suitable for a liquid crystal panel and supplies it to a timing controller.

The timing controller supplies red, green, and blue digital image data and control signals from the video card to the data driver. The control signal for driving the gate driver is generated and supplied to the gate driver.

The gate driver sequentially generates scan pulses in response to a control signal input from the timing controller and sequentially supplies the scan pulses to the gate lines.

The data driver receives red, green, and blue digital image data and control signals input from the timing controller, and converts the digital image data signals into analog image signals and supplies them to the data lines in response to the control signals.

As shown in FIG. 1, the power supply unit 10 receives a voltage from an external source and generates and supplies a driving voltage for driving a gate driver, a data driver, a gamma voltage generator, a common voltage generator, and a timing controller. At this time, the remaining power supply unit other than the timing controller including the digital circuit and the data driver is supplied from the DC / DC converter 12 using the PWM-IC. The DC / DC converter 12 uses a method of boosting input power.

However, the DC / DC converter 12 consumes power according to the efficiency of the PWM-IC when boosting the voltage. In addition, the circuit configuration is complicated and the number of parts used increases the cost.

In order to solve the above problems, it is an object of the present invention to provide a liquid crystal display device and a driving method thereof having improved power consumption by providing a second power supply.

In order to achieve the above object, the present invention generates and supplies a common voltage, a gate on voltage and a gate off voltage using a first power supply unit for supplying a first driving voltage and a second driving voltage input from the outside. Provided is a liquid crystal display device including a second power supply unit.

The first power supply unit supplies a driving voltage to a timing controller including a digital circuit and a data driver.

The second power supply unit may include a pulse modulator, a gate on voltage generator, and a gate off voltage generator.

The pulse modulator may include a switching element and control the switching element through a pulse signal input from the timing controller to output the voltage as an AC waveform.

The gate-on voltage generator includes a first boost circuit and boosts and outputs the second driving voltage and the voltage input from the pulse modulator through the first boost circuit.

The gate-off voltage generator may further include a second boosting circuit between the pulse modulator and the base voltage to output a voltage boosted by inverting the voltage output from the pulse modulator.

The second driving voltage is a voltage for driving the light source driving inverter of the liquid crystal display module.

In order to achieve the above object, the present invention provides a first driving voltage to a timing controller and a data driver including a digital circuit in the first power supply unit, and a second driving voltage input from the outside from the second power supply unit. Generating and supplying a common voltage, a gate on voltage, and a gate off voltage by using the first and second power supplies; and driving the gate driver and the data driver using voltages supplied from the first and second power supplies and the timing controller. And a driving signal supplied to the gate signal and driving the liquid crystal display panel with the driving signals supplied to the gate line and the data line.

The generating of the gate on voltage and the gate off voltage may include generating a gate on voltage by controlling a switching device through a pulse signal input from a timing controller in a pulse modulator to output the second driving voltage as a voltage of an AC waveform. And supplying the negative and gate off voltage generators.

The generating of the gate on voltage may further include amplifying and outputting the second driving voltage and the voltage output from the pulse modulator in a first boosting circuit provided in the gate on voltage generator.

The generating of the gate off voltage may further include inverting and amplifying the voltage input from the pulse modulator in the second boosting circuit provided in the gate off voltage generator.

Other objects and features of the present invention in addition to the above object will be apparent through the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 6.

2 is a block diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 3 is a block diagram showing driving voltages output from the first and second power supplies shown in FIG. 2.

2 to 4, a liquid crystal display according to an exemplary embodiment of the present invention may include a data driver 180 driving a data line DL and a gate driver driving a gate line GL of the liquid crystal panel 200. The timing controller 120 supplies a control signal to the data driver 180 and the gate driver 170, and supplies a first driving voltage VDD to the timing controller 120 and the data driver 180. The common electrode and the gate driver by generating the common voltage Vcom, the gate-on voltage Von, and the gate-off voltage Voff using the first power supply unit 100 and the second driving voltage V2 input from the outside. And a second power supply 110 for supplying the data driver 180 and the data driver 180.

In detail, the first power supply unit 100 outputs the first input voltage V1 of 3.3V supplied from the outside as the first driving voltage VDD to supply the timing controller 120 and the data driver 180. .

The timing controller 120 receives the first driving voltage VDD and supplies red, green, and blue digital video data input from an external control board (not shown) to the data driver 180, and provides horizontal / vertical synchronization. The clock signal CK is generated using the signal to control the data driver 180, and the gate CP is generated by generating a signal CPV, a gate start pulse GPS, an output control signal OE, and the like to select a next gate line. The driving unit 170 is controlled. In particular, the signal CPV for selecting the next gate line or the output control signal OE of the gate driver 170 are supplied to the pulse modulator 140 included in the second power supply 110.

The second power supply unit 110 receives a voltage V2 of 8V to 12V supplied to the light source driving inverter, thereby providing the data driver 180, the common voltage generator 130, the gate-on voltage generator 160, and the gate. Supply to the off voltage generator 150.

In detail, the second power supply unit 110 includes a common voltage generator 130, a gate on voltage generator 160, and a gate off voltage generator 150.

The common voltage generator 130 receives the second driving voltage AVDD to supply voltage to the common electrode by dropping the voltage or stabilizing the voltage through a resistor or a regulator.

The gate on voltage generator 160 and the gate off voltage generator 150 generate the gate on voltage Von and the gate off voltage Voff and supply them to the gate driver 170. The gate on voltage generator 160 and the gate off voltage generator 150 may further include a separate pulse modulator 140 and boost circuits because the gate on voltage generator 160 and the gate off voltage generator 150 are greater than the second driving voltage AVDD.

4 is a diagram illustrating a pulse modulator included in the second power generator illustrated in FIG. 3, FIG. 5 is a diagram illustrating a gate-on voltage generator illustrated in FIG. 3, and FIG. 6 is illustrated in FIG. 3. A diagram illustrating a gate off voltage generator.

As shown in FIG. 4, the pulse modulator 140 may include any one of an input second driving voltage V2 and a gate line selection signal CPV or a gate driver output control signal OE supplied from the timing controller 120. The second driving voltage V2 is output in the form of an AC waveform. To this end, the pulse modulator 140 includes the switching element TR1, and the second driving voltage V2 is modulated according to the pulse of the timing controller 120 to output the pulse modulated voltage Vm in the form of an AC pulse.

Referring to FIG. 5, the gate-on voltage generator 160 includes a first pumping circuit 161 which adds and outputs a second driving voltage AVDD and a pulse modulating voltage Vm. The first pumping circuit 161 charges the second driving voltage AVDD and the voltages charged in the first to fourth capacitors C1 to C4 and the capacitors C1 to C4 that charge the pulse modulation voltage Vm. Is supplied between the first to fourth diodes D1 to D4 connected in series between the output terminals, and two voltages are added to output a gate-on voltage Von greater than the second driving voltage AVDD.

Referring to FIG. 6, the gate-off voltage generator 150 includes a second pumping circuit 151 for inverting and amplifying the second driving voltage AVDD. The second pumping circuit 151 may include the fifth to eighth diodes connected in series with the voltage charged by the fifth to eighth capacitors C5 to C8 that are charged with the second driving voltage AVDD and the ground voltage in the reverse direction to the ground. The second driving voltage AVDD is inverted and amplified by being supplied between D5 and D8 to output the gate-off voltage Voff.

The gate on voltage Von and the gate off voltage Voff generated by the gate on voltage generator 160 and the gate off voltage generator 150 are supplied to the gate driver 170.

The gate driver 170 sequentially supplies the gate on voltage Von and the gate off voltage Voff to the gate line GL through a control signal input from the timing controller 120. In response to the gate start pulse GSP input from the timing controller 120, the gate on voltage Von and the gate off voltage Voff are sequentially supplied to the gate line GL, and the thin film connected to the gate line GL. The gate driving voltage of the gate on voltage Von and the gate off voltage Voff is supplied to the gate electrode of the transistor TFT. In response to the gate driving voltage input from the gate driver 170, an image signal on the data line DL is supplied to the pixel electrode of the liquid crystal cell Clc by the thin film transistor.

The data driver 180 converts the control signal input from the timing controller 120 and the corrected data input from the gamma voltage generator into analog data and supplies the analog data to each data line DL. The gamma voltage generator included in the data driver 180 grounds the second driving voltage AVDD supplied from the second power supply 110 and the red, green, and blue image data signals supplied from the timing controller 120. The voltage of the contact point between the plurality of resistors is generated between the second drive voltage AVDD and the second drive voltage AVDD. The gamma voltage corresponding to the gamma value of the data is generated in consideration of the electrical / optical characteristics of the liquid crystal panel 200. The gamma voltage generated from the gamma voltage generator is set to have a different voltage level in response to the gamma value selected in the expressible range. The gamma voltage is supplied to the data driver 180.

The liquid crystal panel 30 driven by the gate driving signal and the data driving signal to display an image includes a thin film transistor substrate and a color filter substrate facing the thin film transistor substrate. Liquid crystal is injected between the thin film transistor substrate and the color filter substrate, and an image is displayed by controlling the light transmittance of the liquid crystal using a thin film transistor (TFT) as a switching element.

In the thin film transistor substrate, the thin film transistor TFT is formed in a pixel region formed by crossing the gate line GL and the data line DL. The thin film transistor TFT transmits the image signal supplied from the data line DL to the pixel electrode in response to the gate driving signal supplied from the gate line GL. The pixel electrode applies a pixel voltage to the liquid crystal using the image signal charged therein.

The color filter substrate includes a color filter divided by a black matrix to display an image through light incident through liquid crystal.

The liquid crystal panel 30 is driven by driving signals supplied from the gate driver 170 and the data driver 170 to display an image.

Since the liquid crystal display according to the exemplary embodiment of the present invention uses a voltage of 8V to 12V applied from the outside, power loss can be reduced by removing the DC / DC converter.

7 is a flowchart sequentially illustrating a method of driving a liquid crystal display according to the present invention.

Referring to FIG. 7, a method of driving a liquid crystal display according to the present invention includes supplying a first driving voltage to a timing controller and a data driver including a digital circuit from a first power supply (S10) and a second power supply. Generating and supplying a common voltage, a gate-on voltage, and a gate-off voltage using a second driving voltage input from an external device (S20), and a gate driver using voltages supplied from the first and second power supplies and the timing controller. And driving the data driver to supply driving signals to the gate lines and the data lines (S30), and driving the liquid crystal panel with the driving signals supplied to the gate lines and the data lines (S40).

Specifically, the first power supply unit supplies the first driving voltage to the timing controller including the data circuit and the data driver. The timing controller generates and supplies control signals to the gate driver and the data driver, and supplies red, green, and blue image signals to the data driver. In addition, one of the pulse signals supplied from the timing controller to the gate driver is supplied to the pulse driver provided in the second power supply unit.

The common voltage, the gate on voltage, and the gate off voltage are generated using the second driving voltage input from the outside and supplied to the common electrode and the gate driver. In addition, the second driving voltage is supplied to the gamma voltage generator. Here, the second power generator includes a pulse modulator, a gate on voltage generator, and a gate off voltage generator, and generates and supplies driving voltages in each voltage generator. On the other hand, the common voltage is supplied to the common electrode by stabilizing the voltage or dropping the voltage using the input second driving voltage using a regulator or a resistor.

The pulse modulator receives the second driving voltage to generate an AC waveform voltage through a pulse signal supplied from the timing controller, and supplies the voltage to the gate on voltage generator and the gate off voltage generator. The voltage applied from the pulse modulator and the second driving signal are boosted through the first booster circuit to supply a gate-on voltage to the gate driver, and the gate driver is inverted and amplified by the voltage booster from the pulse booster. Supply the gate-off voltage to the The second power supply unit supplies the second driving voltage to the data driver.

The gate driver receives a control signal input from a timing controller, a gate on voltage, and a gate off voltage to sequentially drive the gate line of the liquid crystal panel.

The data driver receives the first driving voltage input from the first power supply unit, the second driving voltage input from the second driving unit, the control signal input from the timing controller, and the image signal of red, green, and blue to receive data lines on the liquid crystal panel. Drive it.

In the liquid crystal panel, the thin film transistor is driven by driving signals input from the gate driver and the data driver to display an image.

As described above, the LCD and the driving method thereof according to the present invention can improve power consumption by removing the DC / DC converter through the second power supply using the inverter driving voltage for driving the light source. In addition, the material cost can be reduced by removing the DC / DC converter.

The present invention described above will be capable of various substitutions, modifications and changes by those skilled in the art to which the present invention pertains. Accordingly, the present invention should not be limited to the above-described embodiments and the accompanying drawings, and the rights thereof should be determined by the claims.

Claims (11)

A first power supply unit supplying a first driving voltage; And a second power supply unit configured to generate and supply a common voltage, a gate on voltage, and a gate off voltage by using a second driving voltage input from the outside. The method of claim 1, And the first power supply unit supplies a driving voltage to a timing controller including a digital circuit and a data driver. The method of claim 1, And the second power supply unit includes a pulse modulator, a gate on voltage generator, and a gate off voltage generator. The method of claim 3, wherein And the pulse modulator includes a switching element and controls the switching element through a pulse signal input from the timing controller to output the voltage as an AC waveform. The method of claim 3, wherein And the gate-on voltage generator includes a first boost circuit and boosts and outputs the second driving voltage and the voltage input from the pulse modulator through the first boost circuit. The method of claim 3, wherein And the gate-off voltage generator further includes a second boosting circuit between the pulse modulator and a base voltage to output a voltage boosted by inverting the voltage output from the pulse modulator. According to claim 1, The second driving voltage is a voltage for driving the light source driving inverter of the liquid crystal display module. Supplying a first driving voltage to a timing controller including a digital circuit and a data driver in a first power supply; Generating a common voltage, a gate on voltage, and a gate off voltage using a second driving voltage input from the outside in the second power supply unit and supplying the generated common voltage, gate on voltage, and gate off voltage to the gate driver and the common voltage generator; Supplying a driving signal to a gate line and a data line by driving a gate driver and a data driver with voltages supplied from the first and second power supply units and the timing controller; And driving a liquid crystal panel with driving signals supplied to the gate line and the data line. The method of claim 8, Generating the gate on voltage and gate off voltage, Controlling a switching element through a pulse signal input from a timing controller in a pulse modulator, outputting the second driving voltage as a voltage of an AC waveform, and supplying the second driving voltage to the gate on voltage generator and the gate off voltage generator; A method of driving a liquid crystal display device, characterized in that. The method of claim 8, The generating of the gate on voltage And amplifying and outputting the second driving voltage and the voltage output from the pulse modulator in a first boosting circuit provided in the gate-on voltage generator. The method of claim 8, The generating of the gate off voltage And inverting and amplifying the voltage inputted from the pulse modulator in a second boosting circuit provided in the gate-off voltage generator.

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