KR20020057407A - Liquid crystal display device with a function of brightness control and driving method and apparatus for therefor - Google Patents

Abstract

PURPOSE: A liquid crystal display having a luminance level control function, a method and an apparatus for driving the liquid crystal display are provided to control the luminance of a back light according to the brightest data among R, G and B video data items to obtain clear pictures. CONSTITUTION: A liquid crystal display having a luminance level control function includes a timing controller(100), a back light driver(200), a back light unit(300), a gate driver(600), a data driver(400), and an LCD panel(700). The timing controller stores RGB video data items for a m frames, selects the maximum value from the three video data items to store the maximum value for n frames, and averages the maximum data value to generate a luminance level control signal according to the averaged data. The back light driver outputs a back light driving voltage according to the luminance level control signal. The back light unit outputs lights according to the driving voltage. The gate driver outputs a scan signal, and the date driver outputs a video signal. The LCD panel displays the video signal according to the lights emitted from the back light unit.

Description

Liquid crystal display device with a function of brightness control and driving method and apparatus for therefor}

The present invention relates to a liquid crystal display device, a driving method thereof, and a driving device thereof, and more particularly, to a liquid crystal display device having a brightness level control function, a driving method thereof, and a driving device thereof.

In general, a liquid crystal display device (hereinafter, LCD) is an apparatus for displaying an image by selectively transmitting light generated from a light source on a rear surface by selectively transmitting each pixel of the panel as a kind of an optical switch. That is, while the brightness is controlled by adjusting the intensity of the electron beam scanned by the conventional CRT, the LCD controls the brightness of the screen by controlling the intensity of light generated from the light source.

BACKGROUND ART [0002] A back level control technique of LCDs, which has been proposed in recent years, is to change the brightness of a light source in accordance with data displayed on a panel. In general, a screen with a lot of bright data increases the brightness of the light source to make it brighter, and a screen with a lot of dark data lowers the brightness of the light source to make it darker, thereby increasing the contrast.

In addition, the effect of increasing contrast and reducing power consumption and flicker has been proposed.

On the other hand, the method of controlling the luminance of the backlight of the LCD is mainly to control the tube current of the lamp, inputting a signal to the inverter circuit to change the duty ratio (the ratio of the section of the high level state to the logic signal of one cycle) according to the luminance. In general, brightness is controlled by changing the level of the DC voltage.

However, these conventional brightness level control methods usually calculate the entire data of the screen to determine the brightness of the lamp. For example, when the entire screen is white, the brightness of the lamp is the highest, and when the entire screen is black, the brightness of the lamp is the lowest. In order to realize this, the power consumed by the analog blocks of the LCD is sensed, and as the power consumption increases, the brightness of the lamp decreases.

However, this method is suitable for black and white screens but is problematic for color screens. In other words, if the entire screen is blue, this is often the case. For example, if the background color of the document is blue, the luminance should be brightened to the same level as if the entire color is white. Since the red pixel is actually a black state, there is a problem that the luminance of the light source is lower than that of the entire white. In other words, the conventional method is not suitable for monochromatic screens, not monochrome screens.

Accordingly, the present invention has been made in an effort to solve such a conventional problem, and an object of the present invention is to provide a liquid crystal display device having a brightness level control function applicable to a monochrome screen as well as a monochrome screen.

Another object of the present invention is to provide a method of driving a liquid crystal display device having the above-described brightness level control function.

Still another object of the present invention is to provide a driving device of the liquid crystal display device having the above-described brightness level control function.

1 is a view for explaining a liquid crystal display having a brightness level control function according to an embodiment of the present invention.

2 is a flowchart illustrating a method of driving a liquid crystal display device having a brightness level control function according to an exemplary embodiment of the present invention.

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

100: timing control unit 110: R data accumulation unit

120: G data accumulator 130: B data accumulator

140: highest value selection unit 150: highest value accumulation unit

160: averaging unit 170: control signal generator

200: backlight drive unit 300: backlight unit

400: data driver 500: driving voltage generator

600: gate driver 700: LCD panel

A liquid crystal display device having a brightness level control function according to one feature for realizing the above object of the present invention,

Firstly storing image data of each RGB applied from the outside for a predetermined m frame, selecting a maximum value of each of the first stored RGB image data for the second time for a predetermined n frame, and storing the second stored maximum data. A timing controller which averages and outputs a luminance level control signal according to the averaged data;

A backlight driver for outputting a backlight driving voltage according to the brightness level control signal;

A backlight unit configured to output a light source according to the backlight driving voltage;

A gate driver for outputting a scan signal;

A data driver for outputting an image signal; And

A plurality of gate lines for transmitting the scan signal, a plurality of data lines for transmitting the image signal intersecting the gate lines, and an area surrounded by the gate lines and the data lines, the respective gate lines and data An LCD panel having a switching element connected to a line and a pixel electrode connected to the switching element and responding to an operation of the switching element, arranged in a matrix type and displaying the image signal according to driving of a light source of the backlight unit; It is made, including. Here, the timing controller may include: an R data accumulator configured to first store R data applied from the outside; A G data accumulation unit configured to first store G data applied from the outside; A B data accumulator for first storing B data applied from the outside; A maximum value selector configured to select a maximum value among first data stored in the R, G, and B data accumulators as the first frame elapses; A peak accumulator for secondly storing the highest data during the second frame; An averaging unit averaging the highest data stored in the highest value accumulating unit and the highest data selected by the highest value selecting unit as the second frame elapses; And a control signal generator for outputting a luminance control signal to the backlight driver in accordance with the averaged peak data output from the averaging unit.

In addition, the n frame is preferably the same as the m frame or a period including the m frame, the average is preferably an arithmetic mean.

In addition, the luminance level control signal is preferably either a pulse width or a DC voltage.

In addition, the driving method of the liquid crystal display device having the brightness level control function according to one feature for realizing the above-described other object of the present invention,

(a) first separating the RGB grayscale data received from the outside and storing the sum of bits corresponding to the grayscale data of each of the separated RGB for m frames;

(b) selecting and outputting grayscale data of the highest value among the sum of the first stored bits for each RGB;

(c) second storing the selected highest gray level data for n frames;

(d) averaging the second stored highest gray level data in step (c) and the highest gray level data selected in step (b); And

(e) outputting a luminance control signal according to the averaged data to drive the backlight of the liquid crystal display.

In addition, a driving device of a liquid crystal display device having a brightness level control function according to one feature for realizing another object of the present invention includes a plurality of gate lines for transmitting a scan signal and intersecting the gate lines. A plurality of data lines for transmitting an image signal, a switching element formed in an area surrounded by the gate line and the data line, and connected to the respective gate line and the data line, and connected to the switching element, A drive device for a liquid crystal display device comprising an LCD panel arranged in a matrix type with pixel electrodes responsive to an operation.

Image data of each RGB applied from the outside is first stored for a predetermined m frame, the highest value of each of the first stored RGB image data is selected and stored second, and the second stored maximum data is averaged for the predetermined n frames. A timing controller configured to output a signal for controlling the luminance level according to the averaged data;

A backlight driver configured to output a backlight driving voltage according to the luminance level control signal provided from the timing controller;

It includes a backlight unit for outputting a light source to the back of the LCD panel according to the backlight driving voltage.

According to the liquid crystal display device having the brightness level control function, the driving method thereof, and the driving device thereof, the luminance of the backlight of the liquid crystal display device can be controlled according to the brightest data by separately processing RGB three-color data.

Then, embodiments will be described so that those skilled in the art can easily implement the present invention.

1 is a view for explaining a liquid crystal display having a brightness level control function according to an embodiment of the present invention.

Referring to FIG. 1, a liquid crystal display having a brightness level control function according to an exemplary embodiment of the present invention may include a timing controller 100, a backlight driver 200, a backlight unit 300, a data driver 400, and a driver. The voltage generator 500, the gate driver 600, and the LCD panel 700 are included.

The timing controller 100 generally has a period and an amplitude of the common electrode voltage Vcom according to the vertical synchronization signal Vsync applied with the RGB image signal from the outside, and the horizontal synchronization signal Hsync and the main clock signal MCLK. Outputs the first signal 101 defining the signal to the driving voltage generator 500, outputs the data driver driving signals LOAD, STH, and RGB to the data driver 400, and outputs a gate driver driving signal ( Gate Clk and STV are outputted to the gate driver 600.

In addition, the timing controller 100 may include an R data accumulator 110, a G data accumulator 120, a B data accumulator 130, a maximum selector 140, a maximum accumulator 150, and an averager 160. And a control signal generator 170 to first store image data of each RGB applied from the outside for a predetermined m frame, select a maximum value of each image data of the first stored RGB, and second store the image data. The second stored highest data is averaged for a predetermined n frame to output a signal for controlling the luminance level according to the averaged data.

In more detail, the R data accumulator 110 first stores R data applied from the outside, the G data accumulator 120 first stores G data applied from the outside, and the B data accumulator 130 ) First stores B data applied from the outside.

The maximum selector 140 selects the highest value among first data stored in the R, G, and B data accumulators 110, 120, and 130 according to the elapse of a predetermined m frame, and selects the highest value data. To the 150 and the averaging unit 160.

The peak accumulation unit 150 stores the peak data second for a predetermined n frame. In this case, the n frame preferably includes a frame before the m frame with a period for the m frame.

The averaging unit 160 averages the second peak data stored in the peak accumulation unit 150 and the peak data selected by the peak selection unit 140 as the n frames elapse, and averages the peak data. The generator 170 is provided.

The control signal generator 170 outputs the brightness control signal to the inverter 200 according to the averaged peak data output from the averaging unit. In this case, the luminance control signal output is in the form of a pulse width or a DC voltage according to the type of the inverter 200 for driving the backlight unit.

The inverter unit 200 receives a brightness control signal from the control signal generator 170 of the timing controller 100 and outputs a driving voltage for driving the backlight unit 300. For example, when a luminance control signal having a high luminance level is applied, a backlight driving voltage having a high potential is output to the backlight unit 300, and when a luminance control signal having a low luminance level is applied, a low potential backlight is applied. The write driving voltage is output to the backlight unit 300.

The backlight unit 300 outputs a light source to the LCD panel 700 in association with the backlight driving voltage provided from the inverter unit 200.

The data driver 400 receives the data driver driving signals LOAD, STH, and RGB from the timing controller 100 and outputs the image signals D1, D2,..., And Dn to the LCD panel 700.

The driving voltage generator 500 receives the first signal 101 from the timing controller 100 to raise or lower its voltage level, and gate driving voltages Von and Voff for driving the gate driver 600. Is output to the gate driver 600, and the common electrode voltage Vcom that is tuned to the gate driving voltage at a predetermined cycle is output to the LCD panel 700.

The gate driver 600 based on the gate driver driving signals Gate Clk and STV provided from the timing controller 100 and the gate driving voltages Von and Voff provided from the driving voltage generator 300. Outputs (G1, G2, ..., Gm) to the LCD panel 700.

The LCD panel 700 includes a plurality of common electrode lines (not shown), m gate lines for transmitting scan signals, n data lines for transmitting image signals intersecting the gate lines, respective gate lines and A backlight unit arranged in a matrix type including a switching element TFT (not shown) connected to data lines and a pixel electrode (not shown) connected to the switching element in response to an operation of the switching element, The image signal is displayed according to the light source driving of 300.

Hereinafter, a liquid crystal display having a brightness level control function according to the present invention will be described in detail.

2 is a flowchart illustrating a method of driving a liquid crystal display device having a brightness level control function according to an exemplary embodiment of the present invention.

1 and 2, first, receive the R, G, B data signals provided from the outside, preferably from the graphics controller, and accumulate the R, G, B data signals respectively. It accumulates in the units 110, 120, and 130 (step S10). In this case, the accumulated R, G, and B data may be input in units of bits. The accumulated R, G, and B data may be accumulated for all the input bits, or may be accumulated for a part of the input. In the case of accumulating a part, it is possible to accumulate only for a certain bit of MSB. For LCDs that use 6-bit data, black is '000000' and white is '111111', so the brighter the screen, the greater the cumulative total.

Subsequently, it is checked whether or not the predetermined m frame has elapsed (step S20), and when it is checked that the m frame is not elapsed, the feedback is returned to step S10, and when the m frame is checked as elapsed, the received R, G, B The highest value of the data is selected (step S30). In this case, the preset m frame is a positive integer of 1 or more.

Subsequently, the highest value data selected in step S30 is stored in the highest value accumulator 150 (step S40), and the data stored for a predetermined n frame is averaged (step S50). In this case, the preset n frame is a positive integer of 1 or more. The reason for taking the average of the stored maximum data is to prevent the brightness of the backlight from changing drastically.

Subsequently, a brightness control signal is output to an inverter for driving the backlight unit of the liquid crystal display according to the averaged data (step S60). In this case, the luminance control signal output is in the form of a pulse width or a DC voltage depending on the type of inverter for driving the backlight unit.

As described above, the present invention can separately process the RGB tricolor data to control the luminance of the backlight of the liquid crystal display according to the brightest data. For example, in the luminance level control method of the present invention, the brightness of the backlight in the case where the whole is white and when the whole is any monochromatic color is the same as the maximum brightness, so that a very clear picture quality can be displayed even on a monochromatic screen.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

As described above, according to the present invention, each image of RGB input to the digital display device is cumulatively calculated for m frames, thereby adjusting the brightness of the backlight according to the brightest data to obtain a clear picture quality. At this time, the cumulative result of the m frames is averaged with the previous n data to determine the final luminance, thereby preventing a sudden change in luminance.

Claims (14)

Firstly storing image data of each RGB applied from the outside for a predetermined m frame, selecting a maximum value of each of the first stored RGB image data for the second time for a predetermined n frame, and storing the second stored maximum data. A timing controller which averages and outputs a luminance level control signal according to the averaged data; A backlight driver for outputting a backlight driving voltage according to the brightness level control signal; A backlight unit configured to output a light source according to the backlight driving voltage; A gate driver for outputting a scan signal; A data driver for outputting an image signal; And A plurality of gate lines for transmitting the scan signal, a plurality of data lines for transmitting the image signal intersecting the gate lines, and an area surrounded by the gate lines and the data lines, the respective gate lines and data An LCD panel having a switching element connected to a line and a pixel electrode connected to the switching element and responding to an operation of the switching element, arranged in a matrix type and displaying the image signal according to driving of a light source of the backlight unit; Liquid crystal display having a brightness level control function comprising a. The method of claim 1, wherein the timing controller, An R data accumulator for first storing R data applied from the outside; A G data accumulator for first storing G data applied from the outside; A B data accumulator for first storing B data applied from the outside; A maximum value selector configured to select a maximum value among first data stored in the R, G, and B data accumulators as the m frame elapses; A maximum accumulator for second storing the highest data for the n frames; An averaging unit averaging the highest data stored in the highest value accumulating unit and the highest data selected by the highest value selecting unit as the n frames elapse; And And a control signal generator for outputting a brightness control signal to the backlight driver in accordance with the averaged peak data output from the averaging unit. The liquid crystal display device according to claim 1 or 2, wherein the n frame is a period equal to or including the m frame. The liquid crystal display device having a brightness level control function according to claim 1 or 2, wherein the average is an arithmetic mean. The liquid crystal display device according to claim 1 or 2, wherein the brightness level control signal is any one of a pulse width and a DC voltage. (a) first separating the RGB grayscale data received from the outside and storing the sum of bits corresponding to the grayscale data of each of the separated RGB for m frames; (b) selecting and outputting grayscale data of the highest value among the sum of the first stored bits for each RGB; (c) second storing the selected highest gray level data for n frames; (d) averaging the second stored highest gray level data in step (c) and the highest gray level data selected in step (b); And (e) driving the backlight of the liquid crystal display by outputting a luminance control signal according to the averaged data Method of driving a liquid crystal display device having a brightness level control function comprising a. 7. The method of claim 6, wherein the n frame is the same as the m frame or includes the n frame. 7. The method of driving a liquid crystal display device having a brightness level control function according to claim 6, wherein the average of said step (d) is an arithmetic mean. 7. The method of claim 6, wherein the luminance level control signal of step (e) is any one of a pulse width and a DC voltage. A plurality of gate lines for transmitting a scan signal, a plurality of data lines for transmitting image signals intersecting the gate lines, and an area surrounded by the gate lines and the data lines, respectively, for each of the gate lines and the data lines. A driving device of a liquid crystal display device comprising an LCD panel arranged in a matrix type having a switching element connected thereto and a pixel electrode connected to the switching element and responsive to an operation of the switching element. Image data of each RGB applied from the outside is first stored for a predetermined m frame, the highest value of each of the first stored RGB image data is selected and stored second, and the second stored maximum data is averaged for the predetermined n frames. A timing controller configured to output a signal for controlling the luminance level according to the averaged data; A backlight driver for outputting a backlight driving voltage according to a brightness level control signal provided from the timing controller; A backlight unit for outputting a light source to a rear surface of the LCD panel according to the backlight driving voltage Driving device of the liquid crystal display device having a brightness level control function comprising a. The method of claim 10, wherein the timing controller, An R data accumulator for first storing R data applied from the outside; A G data accumulator for first storing G data applied from the outside; A B data accumulator for first storing B data applied from the outside; A maximum value selector configured to select a maximum value among first data stored in the R, G, and B data accumulators as the m frame elapses; A maximum accumulator for second storing the highest data for a predetermined n frame; An averaging unit averaging the highest data stored in the highest value accumulating unit and the highest data selected by the highest value selecting unit as the n frames elapse; And A control signal generator for outputting a luminance control signal according to the averaged highest value data output from the averaging unit And a driving device of the liquid crystal display device having a brightness level control function. 12. The driving apparatus of a liquid crystal display device according to claim 10 or 11, wherein the n frame is a period equal to or including the m frame. 12. The drive device for a drive device of a liquid crystal display device according to claim 10 or 11, wherein the average is an arithmetic mean. 12. The liquid crystal display drive device according to claim 10 or 11, wherein the brightness level control signal is any one of a pulse width and a DC voltage.