KR20010049019A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to control the amount of current applied from an inverter to lamp for controlling light quantity of back-light assembly after detecting luminance which exceed threshold value in broadcasting signal. CONSTITUTION: The liquid crystal display device includes a television signal processing part, a liquid crystal panel driving circuit and an inverter(80). The television signal processing part receives the broadcasting signal and detects R,G,B data. When the luminance of the R,G,B signal exceed predetermined threshold value, the television signal processing part generates voltage for luminance control and outputs lamp control signal depending on the voltage. The liquid crystal panel driving circuit displays the picture on the liquid crystal panel according to the R,G,B data and the control signal thereof. The inverter(80) control the amount of current applied to the lamp(90) which provide light for the liquid crystal panel depending on the lamp control signal.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, in order to prevent a saturation state in which an image displayed on a liquid crystal panel is buried in excessive brightness, detecting whether a threshold value of luminance is exceeded in the airborne television broadcast signal, As a result, the present invention relates to a liquid crystal display device that controls the inverter to adjust the brightness of the image.

Cathode ray tube (CRT), which is one of the display devices that are generally used, is mainly used for monitors such as TVs, measuring devices, information terminal devices, etc., but due to the weight and size of the CRT itself, Can't actively respond to demand

In order to solve this problem, flat panel display devices have been developed, and flat panel display devices have the advantage of being thinner and lighter than CRTs, and in particular, liquid crystals using the electro-optic properties of liquid crystals injected into liquid crystal panels. Liquid crystal display devices have been actively developed.

The liquid crystal display device uses the electrical characteristics of the liquid crystal whose light transmittance varies according to the voltage applied to each pixel. The liquid crystal is not a light emitting device for generating light, but a light receiving device for controlling the amount of light coming from the outside and displaying it on the screen. The image is displayed by using a backlight attached to the rear side of the liquid crystal panel.

The liquid crystal display device is not only widely used as a monitor of a portable computer and a desktop type computer because it is lighter, thinner, capable of driving a lower voltage, and consumes less power than other display devices. Its use is increasing.

When used as the above-described television broadcast signal receiver, the liquid crystal display includes a television signal processor for image-processing an air-propagated television broadcast signal, and an image display unit for displaying an image on the liquid crystal panel according to the image-processed data and the data control signal. do.

The television signal processor receives the airborne television broadcast signal through an antenna, separates the carrier color signal from the television broadcast signal, and demodulates the color difference signal to detect three primary colors of R (Red), G (Green), and B (Blue). The image display unit processes the R, G, and B data detected by the television signal processor according to the data control signal and displays the data on the liquid crystal panel.

On the other hand, the screen brightness of the liquid crystal display device is mainly determined by the amount of light of the backlight assembly for providing light to the liquid crystal panel or the arrangement of the liquid crystal of the liquid crystal panel according to the gray scale voltage.

Herein, the light amount of the backlight assembly is controlled by an inverter supplied with an inverter power and converting a DC voltage into an AC voltage and applied to the lamp, and the arrangement state of the liquid crystal is controlled by the level of the gradation voltage.

However, since the inverter operated by receiving inverter power in the conventional liquid crystal display device controls the amount of light of the backlight assembly at a constant level regardless of the luminance of the R, G, and B data detected in the airwave propagated television video signal, The problem is that the image displayed on the panel is locked in a black level on a screen of a dark background or a saturation in which part of the image is buried in excessive brightness on a screen of a bright background.

Accordingly, an object of the present invention is to detect the luminance exceeding the threshold in the air propagated broadcast signal in order to prevent the image displayed on the liquid crystal panel is buried in excessive brightness, and then provided from the inverter to the lamp as the detection result The amount of current to be controlled is controlled to adjust the amount of light in the backlight assembly.

1 is a block diagram showing a liquid crystal display device according to the present invention.

In order to achieve the above object, the present invention, by receiving the air-broadcasted broadcast signal to detect the RGB data, and when the luminance of the RGB data exceeds a predetermined threshold, and generates a voltage for adjusting the brightness corresponding thereto, A television signal processor for outputting a predetermined lamp control signal, a liquid crystal panel driver circuit unit for displaying an image on a liquid crystal panel according to RGB data and RGB data detected by the teleelectric signal processor, and a television signal processor An inverter for controlling the amount of current applied to the lamp for providing light to the liquid crystal panel according to the lamp control signal.

Here, the television signal processing unit receives an air-broadcasted broadcast signal, tunes to a specific frequency band, and outputs a composite video signal, detects RGB data from the composite video signal output from the RF processing unit, and luminance of the RGB data. When the value exceeds the threshold includes an image processor for generating and outputting a voltage for adjusting the brightness, and a microprocessor for controlling to output the RGB data, the control signal and the lamp control signal according to the brightness control voltage to the image display.

In this case, the inverter adjusts the duty range of the amplitude or pulse width in response to the lamp control signal and outputs the control signal, and AC controls the amount of current applied to the lamp according to the control signal output from the inverter control unit. It includes a conversion unit.

Hereinafter, a liquid crystal display according to the present invention will be described with reference to the accompanying drawings.

First, an embodiment according to the present invention comprises a television signal processor and an image display unit, and the television signal processor includes an RF processor 10, an image processor 20, and a microprocessor 30, and the image display unit includes a liquid crystal panel. It includes a circuit portion and an inverter for driving.

Specifically, the RF (Radio Frequancy) processor 10 receives an RF broadcast signal, which is a broadcast signal of a television broadcast signal, demodulates a specific frequency band, that is, a predetermined channel, and outputs the composite video signal.

The image processor 20 has a Y signal, which is a luminance signal representing luminance (brightness) of an image, and a C signal, which is a color signal, or R, G, or B type, in a composite video signal, which is a broadcast signal of a channel selected by the RF processor 10. Detect the video signal.

In addition, the image processor 20 detects the luminance signal level of the image displayed on the liquid crystal panel 120, and generates and outputs a voltage for adjusting the luminance when the detected luminance signal level exceeds a predetermined threshold.

The microprocessor 30 controls to input the R, G, and B image signals and the control signal detected by the image processor 20 to the timing controller 50, and according to the predetermined voltage according to the brightness control voltage output from the image processor 20. The control signal of the output to the inverter 80 to be described later.

The inverter 80 outputs from the inverter control unit 81 and the inverter control unit 81 to adjust the output signal using any one of a pulse width modulation method for adjusting the duty of the pulse and an amplitude modulation method for adjusting the amplitude. It includes an AC converter 82 for adjusting the amount of current provided to the lamp 90 according to the control signal.

The inverter controller 81 and the AC converter 82 are configured to operate by receiving inverter power of a DC component having a predetermined level, respectively, and the inverter controller 81 is a predetermined control signal output from the microprocessor 30 ( In the following description, a " lamp control signal " is applied. The inverter controller 81 applies a control signal of an amplitude modulation method or a pulse width modulation method to the AC converter 82, and converts the AC converter 82. Is configured to adjust the amount of current supplied to the lamp 90 by the control signal.

The lamp 90 emits light to the liquid crystal panel 120 according to an AC voltage supplied from the inverter 80.

On the other hand, the power supply unit 40 to which the DC power is applied supplies a voltage necessary for the operation of the timing controller 50, the gray scale generator 60, and the gate voltage generator 70.

The timing controller 50 is configured to output various control signals and R, G, and B data to the source drive IC 100 electrically connected to the liquid crystal panel 120, and to output various control signals to the gate drive IC 110. do.

The gray scale generator 60 generates a plurality of levels of voltages corresponding to the number of gray scales using the voltage applied from the power supply unit 40 and applies the gray scale voltage to the source drive IC 100 as a gray scale voltage.

The gate voltage generator 70 supplies a voltage for generating turn-on / turn-off voltage to the gate drive IC 110.

In the gate and source drive ICs 100 and 110 electrically connected to the liquid crystal panel 120, the source signal and the gate signal supplied from the timing controller 50, the gray scale generator 60, and the gate voltage generator 70 are provided. Is applied to the liquid crystal panel 120.

The liquid crystal panel 120 displays an image by passing the light emitted from the lamp 90 according to the source signal and the gate signal.

Looking at the operation of the liquid crystal display according to the present invention having such a configuration, the power supply unit 40 is applied to the DC power supply to the operation of the timing controller 50, the gray scale generator 60 and the gate voltage generator 70 The required voltage is applied and inverter power is applied to the inverter 80.

The R, G, and B data detected by image detection by the RF processor 10 and the image processor 20 by receiving the air-broadcasted RF broadcast signal are transmitted to the timing controller 50, and the timing controller 50 includes R, G and B data and a control signal input from the microprocessor 30 are supplied to the source drive IC 100.

The source drive IC 100 generates a data signal using the R, G, and B data generated by the timing controller 50 and the gray scale generator 60, the data control signal, and the gray voltages, and provides the data signal to the liquid crystal panel 120. The gate drive IC 110 generates a gate signal using the gate control signal of the microprocessor 30 and the gate on / off voltage of the gate voltage generator 70 and provides the gate signal to the liquid crystal panel 120.

The liquid crystal panel 120 forms a screen using a gate signal and a data signal. Projection of light is required for the screen to be displayed, and the light is provided by the lamp 90.

The lamp 90 emits light by the AC voltage provided from the AC converter 82 of the inverter 80 to provide light to the liquid crystal panel 120, and the AC converter 82 is provided from the inverter controller 81. The amount of current provided to the lamp 90 is controlled by the control signal.

In detail, the image processor 20 detects brightness signals of R, G, and B data, that is, brightness signals of data, and outputs a voltage for adjusting brightness when the brightness signal of the detected data exceeds a threshold. Transfer to processor 30.

The microprocessor 30 detects a level of the brightness control voltage output from the image processor 20, and outputs a lamp control signal having a DC level corresponding to the detected brightness control voltage to the inverter 80.

When the inverter 80, which is operated by receiving inverter power, receives a predetermined lamp control signal corresponding to the voltage for adjusting brightness from the microprocessor 30 to the inverter controller 81, the inverter controller 81 controls the level of the lamp control signal. The control signal is output by adjusting the amplitude range or the duty of the pulse width. The scale of the current provided from the AC converter 82 to the lamp 90 varies according to the control signal output from the inverter controller 81, and thus the amount of light emitted from the lamp 90 also varies.

That is, the amount of light emitted from the lamp 90 to the liquid crystal panel 120 is changed according to the amount of current provided from the inverter 80. Therefore, the amount of current output from the inverter 80 to the lamp 90 is controlled in accordance with the brightness adjustment voltage level corresponding to the brightness of the data exceeding the threshold, and the amount of light emitted from the lamp 90 is also reduced, The brightness of the liquid crystal panel 120 displaying the image by passing the light emitted from the lamp 90 is also reduced.

If it is determined that the brightness of the image displayed in this way exceeds the threshold, the amount of light emitted from the lamp is controlled, and the brightness of the displayed image is adjusted.

As described above, according to the present invention, since the amount of light of the lamp is controlled according to the degree to which the luminance of the data exceeds the threshold value in the airborne broadcast signal, the image displayed on the liquid crystal panel is prevented from being buried in excessive brightness. can do.

Claims (3)

Receiving the air-broadcasted broadcast signal to detect the RGB data, if the luminance of the RGB data exceeds a predetermined threshold, generates a voltage for adjusting the brightness, and outputs a predetermined lamp control signal according to the brightness control voltage A television signal processor; A liquid crystal panel driver circuit unit displaying an image on a liquid crystal panel according to the RGB data detected by the telescopic signal processor and a control signal of the RGB data; And an inverter for controlling an amount of current applied to a lamp providing light to the liquid crystal panel according to the lamp control signal output from the television signal processing unit. The method of claim 1, wherein the television signal processing unit, An RF processor for receiving the airwave broadcast signal, tuning to a specific frequency band, and outputting a composite video signal; An image processor which detects RGB data from the composite image signal output from the RF processor, and generates and outputs a voltage for adjusting luminance corresponding to the luminance of the RGB data when the luminance exceeds the threshold; And a microprocessor configured to output the RGB data, the control signal, and a lamp control signal according to the brightness control voltage to the image display unit. The method of claim 1, wherein the inverter, An inverter controller for outputting a control signal by adjusting an amplitude range or a pulse width duty corresponding to the ramp control signal; And an AC converter configured to adjust an amount of current applied to the lamp according to a control signal output from the inverter controller.