KR101216172B1 - Liquid crystal display - Google Patents

Abstract

The liquid crystal display of the present invention generates a driving voltage for driving the timing controller, the data driver, the gate driver, and the gamma circuit by using the first power supply voltage supplied from the system power supply unit, but the driving voltage is compared to the standby mode and the standby mode. A module power supply unit lowering in the sleep mode; A backlight power supply unit generating a voltage necessary for light emission of a light source of the backlight unit by using a second power supply voltage supplied from the system power supply unit; A first diode provided on a first power line to which the first power voltage is supplied between the system power unit and the module power unit; And a second diode provided on a second power line to which the second power voltage is supplied between the system power supply unit and the backlight power supply unit.

LCD, normal mode, flashing momentarily

Description

[0001] Liquid crystal display [0002]

1 is a simplified configuration diagram of a conventional liquid crystal display.

FIG. 2 is a waveform diagram of a driving voltage and a driving current provided to the liquid crystal display of FIG. 1.

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

FIG. 4 is a configuration diagram of the liquid crystal display further including the backlight assembly backflow prevention unit in FIG. 3.

DESCRIPTION OF THE REFERENCE NUMERALS (S)

100: system power supply unit 200: drive circuit unit

300: liquid crystal panel 400: backlight assembly

500: drive circuit backflow prevention portion 600: backlight assembly backflow prevention portion

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display (LCD), and more particularly, to stably supply a power supply voltage to a backlight assembly by preventing current from flowing back in a driving circuit unit that provides a driving voltage and a driving signal to a liquid crystal panel. It relates to a liquid crystal display device that can be provided.

In today's information society, the role of electronic displays has become very important, and various electronic displays have been widely used in various industrial fields. In the electronic display device field, electronic display devices having new functions suitable for the demands of the information society, which have been continuously developed and diversified, are continuously being developed. In general, an electronic display device refers to a device that transmits various pieces of information to a human through vision. That is, an electronic display device refers to an electronic device that converts an electronic information signal output from various electronic devices into an optical information signal that can be recognized by a human eye, and is a device that plays a role of a bridge between humans and electronic devices. It can be said.

In such an electronic display device, when an optical information signal is displayed by a light emitting phenomenon, it is referred to as a light emitting display device, and when it is displayed by light modulation due to reflection, scattering, or interference phenomenon, it is called a light receiving display device. Light emitting displays, also called active display devices, include cathode ray tubes (CRTs), plasma display panels (PDPs), organic electroluminescent displays (OELDs), light emitting diodes ( Light Emitting Diode (LED) etc. can be mentioned. The light receiving display device, which is called a passive display device, may include a liquid crystal display (LCD) and an electrophoretic image display (EPID).

Cathode ray tube display device, which is used for television and computer monitor, and has the longest history, has the highest market share in terms of economy, but has many disadvantages such as heavy weight, large volume and high power consumption. .

Recently, due to the rapid progress of semiconductor technology, there is a demand for a flat panel display device as an electronic display device suitable for a new environment in accordance with the trend of lowering and lowering power of various electronic devices and miniaturization, thinning, and lightening of electronic devices. It is rapidly increasing. Accordingly, flat panel display devices such as a liquid crystal display (LCD), a plasma display device (PDP), an organic EL display device (OELD), and the like have been developed, and among these flat panel display devices, it is easy to miniaturize, light weight, and thinner. In particular, liquid crystal display devices having low power consumption and low driving voltage are drawing attention.

A liquid crystal display device injects a liquid crystal material having anisotropic dielectric constant between a color filter substrate on which a common electrode, a color filter, a black matrix, and the like are formed, and an array substrate on which a switching element, a pixel electrode, and the like are formed, and common with the pixel electrode. The display device expresses a desired image by adjusting the intensity of an electric field formed in the liquid crystal material by applying different potentials to the electrodes to change the molecular arrangement of the liquid crystal material, and thereby controlling the amount of light transmitted through the array substrate. In the liquid crystal display, a thin film transistor liquid crystal display (TFT LCD) using a thin film transistor (TFT) element as a switching element is mainly used.

A conventional liquid crystal display device will be described with reference to FIGS. 1 and 2. 1 is a simplified configuration diagram of a liquid crystal display of the prior art. FIG. 2 is a waveform diagram of a driving voltage and a driving current provided to the liquid crystal display of FIG. 1.

The conventional liquid crystal display device includes a liquid crystal panel 30, a driving circuit 20, a backlight assembly 40, and a system power supply 10.

The liquid crystal panel 30 includes a plurality of pixels, displays an image on each pixel, and the driving circuit unit 20 provides a driving voltage VDD and a driving signal for driving the liquid crystal panel 30, and a backlight. The assembly 40 provides light for displaying an image to each pixel of the liquid crystal panel 30, and the system power supply unit 10 supplies the power supply voltages VCC1 and VCC2 to the driving circuit unit 20 and the backlight assembly 40. to provide.

In the conventional liquid crystal display, in order to reduce power consumption, the driving circuit unit 20 is divided into a normal mode, a standby mode, a sleep mode, and the like, so that the liquid crystal panel 30 is reduced. ) Provides a driving voltage VDD and a lower driving voltage VDD in the standby mode or the sleep mode than in the normal mode.

When the driving circuit unit 20 operates in the normal mode and then switches to the standby mode or the sleep mode, the electric charges charged in the driving circuit unit 20 are discharged, so that the system power supply unit 10 in the driving circuit unit 20 is discharged. Current is reversed.

In the conventional liquid crystal display, as shown in FIG. 1, the system power supply unit 10 provides the power supply voltages VCC1 and VCC2 to the driving circuit unit 20 and the backlight assembly 40, and the system power supply unit in the driving circuit unit 20. When the current flows back to 10, the power supply voltage VCC1 provided from the system power supply unit 10 to the driving circuit unit 20 is increased to supply the power supply voltage VCC2 provided from the system power supply unit 10 to the backlight assembly 40. ) Is reduced.

Specifically, in the case where the driving circuit unit 20 switches from the normal mode to the standby mode to operate, as shown in FIG. 2, the driving circuit unit 20 drives the driving voltage of 3 V to the liquid crystal panel 30 in the normal mode. (VDD), in the standby mode, the driving voltage VDD of 2V is supplied to the liquid crystal panel 30, and current is reversed from the driving circuit unit 20 to the system power supply unit 10, thereby providing the system power supply unit 10. The power supply voltage VCC1 provided to the driving circuit unit 20 is increased from 3V to 3.8V at the time when the power supply voltage VCC1 is changed from the normal mode to the standby mode. As a result, the current IBA provided to the backlight assembly 40 is reduced at the point of transition from the normal mode to the standby mode.

In the conventional liquid crystal display, the current flows back from the driving circuit unit 20 to the system power supply unit 10, whereby the power supply voltages VCC1 and VCC2 provided to the backlight assembly 40 are changed, and the backlight assembly 40 is instantaneously. Can cause spot flicker defects.

SUMMARY OF THE INVENTION The present invention has been made in an effort to solve the above problems from a driving circuit unit of a liquid crystal panel when an operation mode of a liquid crystal display device in which a power supply voltage is supplied to each of the driving circuit unit and a backlight assembly of the liquid crystal panel is changed from a normal mode to a standby mode or a sleep mode. An object of the present invention is to provide a liquid crystal display device capable of preventing a backflow phenomenon in which current flows toward a system power supply unit.

The technical objects to be achieved by the present invention are not limited to the technical matters mentioned above, and other technical subjects which are not mentioned can be clearly understood by those skilled in the art from the following description. There will be.

The liquid crystal display of the present invention includes a system power supply for generating a first power supply voltage and a second power supply voltage; A liquid crystal panel comprising a plurality of pixels divided into a plurality of gate lines and a plurality of data lines crossing each other, and displaying an image on each pixel; A gate driver sequentially supplying scan signals to the gate lines; A data driver converting a video data signal into a video voltage signal, which is an analog signal, and supplying the converted data voltage to the data lines; A gamma circuit for supplying a gamma voltage which is preset to have a different voltage level according to the voltage level of the video data signal to the data driver; A timing controller which transmits the video data signal to the data driver and generates control signals for controlling operation timing of the gate driver and the gate driver; A driving voltage necessary for driving the timing controller, the data driver, the gate driver, and the gamma circuit is generated by using the first power voltage supplied from the system power supply unit, but the driving voltage is lowered in the standby mode than in the normal mode. Module power supply; A backlight unit provided at a rear side of the liquid crystal panel to irradiate light to the liquid crystal panel; A backlight power supply unit generating a voltage necessary for light emission of the light source of the backlight unit by using a second power supply voltage supplied from the system power supply unit; A first diode installed on a first power line to which the first power voltage is supplied between the system power supply unit and the module power supply unit, the first diode having a cathode connected to the module power supply unit and an anode connected to the system power supply unit; And a second diode provided between the system power supply unit and the backlight power supply unit, the second power line being supplied with the second power supply voltage, and having a cathode connected to the backlight power supply unit and an anode connected to the system power supply unit.

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Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention, and methods of achieving the same will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. Like reference numerals refer to like elements throughout.

Hereinafter, a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4. 3 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention. FIG. 4 is a configuration diagram of the liquid crystal display further including the backlight assembly backflow prevention unit in FIG. 3.

In the liquid crystal display according to the exemplary embodiment of the present invention, as shown in FIG. 3, the system power supply unit 100, the driving circuit unit 200, the liquid crystal panel 300, the backlight assembly 400, and the driving circuit backflow prevention unit 500 are provided. ), And the like.

The liquid crystal panel 300 is composed of a plurality of pixels divided into gate lines GL0, GL1, GL2,... GLn and data lines DL1, DL2..., DLm that cross each other. At the intersections of the gate lines GL0, GL1, GL2, ..., GLn and the data lines DL1, DL2, ..., DLm, the gate electrode, the pixel electrode, the source electrode, and the drain electrode A thin film transistor TFT is disposed, and each pixel includes a liquid crystal capacitor Clc. The liquid crystal panel 300 includes scan signals and data supplied through gate lines GL1, GL2,..., GLn. An image is displayed on each pixel according to data signals transmitted through the lines DL1, DL2, ..., DLm.

The system power supply unit 100 provides power supply voltages VCC1 and VCC2 to the driving circuit unit 200 and the backlight assembly 400.

The driving circuit unit 200 provides a driving voltage VDD and a driving signal for driving the liquid crystal panel 300, and includes a timing controller 210 and a liquid crystal module (LCM) power supply unit (hereinafter referred to as a “module power supply unit”) ( 220, a gate driver 240, a data driver 250, and a gamma circuit 230. The module power supply unit 220 generates a driving voltage VDD for driving the driving circuit unit 200 using the power supply voltage VCC1 input from the system power supply unit 100 to generate the timing controller 210 and the data driver 250. The gate driver 240 and the gamma circuit 230 are supplied to the gate driver 240 and the gamma circuit 230. The timing controller 210 transmits a video data signal to the data drive, and generates control signals for controlling the operation timing of the gate driver 240 and the gate driver 240. The gate driver 240 sequentially supplies scan signals to the gate lines GL1, GL2,..., GLn in response to a control signal from the timing controller 210. The data driver 250 converts the video data signal from the timing controller 210 into a video voltage signal, which is an analog signal, and provides the converted data voltage to a data line. At this time, the gamma circuit 230 provides the data driver 250 with a gamma voltage that is preset to have a different voltage level according to the voltage level of the video data signal.

The backlight assembly 400 includes a backlight power supply 410 and a backlight unit 420. The backlight power supply unit 410 provides a voltage necessary for lamp emission of the backlight unit 420 by using the power supply voltage VCC2 input from the system power supply unit 100. The backlight unit 420 is installed on the rear surface of the liquid crystal panel 300 to irradiate light to each pixel of the liquid crystal panel 300.

The driving circuit backflow prevention part 500 may be composed of a diode D1. As shown in FIG. 3, the diode D1 is disposed on the first power line to which the power voltage VCC1 is supplied between the system power supply unit 100 and the module power supply unit 220, and is connected to the cathode connected to the module power supply unit 220. An anode connected to the system power supply 100. The diode D1 prevents the current from flowing back from the driving circuit unit 200 to the system power supply unit 100. When the driving circuit unit 200 operates in the normal mode and then switches to the standby mode or the sleep mode, even if the charges charged in the driving circuit unit 200 are discharged, the driving circuit backflow prevention unit 500 is the driving circuit unit. Since the current is prevented from flowing back to the system power supply unit 100 at 200, the power supply voltages VCC1 and VCC2 provided from the system power supply unit 100 to the backlight assembly 400 are not affected. As a result, even when the system power supply unit 100 provides the power supply voltages VCC1 and VCC2 to the driving circuit unit 200 and the backlight assembly 400, the power supply voltage VCC2 can be stably supplied to the backlight assembly 400. The assembly 400 can be effectively suppressed from causing momentary spot flicker failures.

The driving circuit backflow prevention part 500 may be integrally formed with the driving circuit part 200. In particular, the driving circuit backflow prevention part 500 may be integrally formed with the module power supply part 220. Thereby, the drive circuit backflow prevention part 500 can be comprised more simply.

In addition, the liquid crystal display according to the exemplary embodiment of the present invention further includes a backlight assembly backflow prevention unit 600 which prevents current from flowing back from the backlight assembly 400 to the system power supply unit 100 as shown in FIG. 4. Include.

The backlight assembly backflow prevention part 600 may be configured as a diode D2. As shown in FIG. 4, the diode D2 is disposed between the system power supply unit 100 and the backlight power supply unit 410 with a cathode connected to the backlight power supply unit 410 and connected to the backlight power supply unit 410. An anode connected to the system power supply 100. The diode D2 prevents current from flowing back from the backlight assembly 400 to the system power supply 100. Thus, even when the system power supply unit 100 supplies the power supply voltages VCC1 and VCC2 to the driving circuit unit 200 and the backlight assembly 400, the system supply unit 100 is not affected by the backlight assembly 400, and the power supply voltage is supplied to the driving circuit unit 200. (VCC1) can be supplied stably.

The backlight assembly backflow prevention part 600 may be integrally formed with the backlight assembly 400, and in particular, may be integrally formed with the backlight power source 410. As a result, the backlight assembly backflow prevention part 600 can be configured to be simplified.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

Therefore, it should be understood that the above-described embodiments are provided so that those skilled in the art can fully understand the scope of the present invention. Therefore, it should be understood that the embodiments are to be considered in all respects as illustrative and not restrictive, The invention is only defined by the scope of the claims.

The liquid crystal display according to the exemplary embodiment of the present invention configured as described above prevents current from flowing back from the driving circuit unit to the system power supply unit by using the driving circuit backflow prevention unit formed of a diode. When the driving circuit part operates in the normal mode and then switches to the standby mode or the sleep mode, even if the charges charged in the driving circuit part are discharged, the driving circuit backflow prevention part prevents the current from flowing back from the driving circuit part to the system power supply part. Therefore, it does not affect the power supply voltage provided from the system power supply unit to the backlight assembly. As a result, even when the system power supply unit supplies the power supply voltage to the driving circuit unit and the backlight assembly, the power supply voltage can be stably supplied to the backlight assembly, thereby effectively suppressing the backlight assembly from causing an instant spot flicker.

In addition, the liquid crystal display according to the exemplary embodiment of the present invention further includes a backlight assembly backflow prevention unit that prevents current from flowing backward from the backlight assembly to the system power supply unit, thereby providing a power supply voltage to the driving circuit unit and the backlight assembly. The power supply voltage can be stably supplied to the driving circuit unit without being affected by the backlight assembly.

Claims (6)

In a liquid crystal display device in which an operation mode is divided into a normal mode, a standby mode, and a sleep mode to reduce power consumption, A system power supply unit generating a first power supply voltage and a second power supply voltage; A liquid crystal panel comprising a plurality of pixels divided into a plurality of gate lines and a plurality of data lines crossing each other, and displaying an image on each pixel; A gate driver sequentially supplying scan signals to the gate lines; A data driver converting a video data signal into a video voltage signal, which is an analog signal, and supplying the converted data voltage to the data lines; A gamma circuit for supplying a gamma voltage which is preset to have a different voltage level according to the voltage level of the video data signal to the data driver; A timing controller which transmits the video data signal to the data driver and generates control signals for controlling operation timing of the gate driver and the gate driver; A driving voltage necessary for driving the timing controller, the data driver, the gate driver, and the gamma circuit is generated by using the first power voltage supplied from the system power supply, and the driving voltage is compared with the normal mode. And a module power supply unit lowering the sleep mode. A backlight unit provided at a rear side of the liquid crystal panel to irradiate light to the liquid crystal panel; A backlight power supply unit generating a voltage necessary for light emission of the light source of the backlight unit by using a second power supply voltage supplied from the system power supply unit; A first diode installed on a first power line to which the first power voltage is supplied between the system power supply unit and the module power supply unit, the first diode having a cathode connected to the module power supply unit and an anode connected to the system power supply unit; And And a second diode provided between the system power supply unit and the backlight power supply unit, the second power wire being supplied with the second power supply voltage, and having a cathode connected to the backlight power supply unit and an anode connected to the system power supply unit. Liquid crystal display. delete delete delete delete delete

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