KR20080062131A - Driving circuit for liquid crystal display and method of driving the same - Google Patents

Abstract

A circuit and a method for driving an LCD device are provided to reduce power consumption by driving lamps using luminance control signals, which are generated based on an analyzed luminance of image data. A circuit for driving an LCD(Liquid Crystal Display) device includes an LCD panel(11), gate and data drivers(11a,11b), a backlight unit(35), a timing controller(23), and a DC/DC(Direct Current) converter(24). The gate and data drivers supply a driving voltage and a data signal to the LCD panel. The backlight unit includes lamps for supplying lights to the LCD panel and an inverter for controlling the lamps. The timing controller generates control signals for controlling the inverter based on R,G,B video signals supplied from outside. The DC/DC converter outputs a driving voltage, and gate low and high voltage signals required for respective parts.

Description

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

1 is a diagram illustrating a general liquid crystal display device structure.

2 is a view showing the structure of a liquid crystal display device having an adaptive brightness increasing function according to the present invention.

3 is a diagram illustrating a state in which a control signal is generated for driving a multi-segmented backlight unit according to the present invention.

4 is a diagram illustrating a driving state of a lamp using a multi-division backlight control signal generated from an adaptive luminance increasing circuit according to the present invention.

* Description of the symbols for the main parts of the drawings *

11: LCD panel 11a: gate driver

11b: data driver 12: drive circuit section

23: timing controller 31: AI calculator

24: DC-DC converter 25: External storage

34: inverter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device. More particularly, the present invention relates to a liquid crystal display driving circuit and a method of driving the same, by adjusting luminance to have an accurate contrast ratio and improving image quality.

In general, a liquid crystal display device is formed by bonding a thin film transistor array substrate and a color filter substrate to a predetermined cell-gap so as to face each other, and filling liquid crystal in the cell-gap. A liquid crystal display panel includes a liquid crystal display panel, a driver for driving the liquid crystal display panel, and a backlight unit for supplying light to the liquid crystal display panel.

1 is a diagram illustrating a general liquid crystal display device structure.

Referring to FIG. 1, a liquid crystal display includes a timing controller 2 that receives external data DATA including image information and various control signals and supplies the same to a driving timing to each internal device, and a plurality of timing controllers. The liquid crystal display panel 1 arranged such that the data lines D1 to Dm and the gate lines G1 to Gn intersect with each other, and image information and a control signal are applied from the timing controller 2 to the liquid crystal display panel 1. A data driver 4 for applying image information to the image sensor, a gate driver 6 for receiving a control signal from the timing controller 2 and applying a scan signal to the liquid crystal display panel 1, The inverter 8 is configured to control the amount of light and the blinking of the lamp unit 10 by the signal of the timing controller 2.

The timing controller 2 receives data DATA from a medium such as an external graphic card, and transmits various control signals and image information included in the data DATA to the data driver 4 and the gate driver. Corresponding to (6), respectively, and applying the driving timing so that the data driver 4 and the gate driver 6 are organically driven.

On the liquid crystal display panel 1, pixels (not shown) partitioned by crossing the gate lines G1 to Gn and the data lines D1 to Dm are arranged in a matrix form. Since the pixels are electrically connected to the gate lines G1 to Gn and the data lines D1 to Dm, the pixels are activated in units of horizontal lines by a scan signal applied from the gate driver 6 to the data lines D1 to Dm. Image information is received.

The inverter 8 receives a dimming control signal DCS1 for controlling the luminance of the lamp unit 10 from the timing controller 2. The inverter 8 receives DC power from the inside of the liquid crystal display, converts it into AC, and boosts the voltage to high voltage. The lamp unit 10 is turned on by the high voltage applied from the inverter 8, and the amount of light is controlled by the tube current which is an alternating current. The lamp unit 10 is usually composed of a plurality of lamps, the direct type is disposed on the back of the liquid crystal display panel 1 at regular intervals is mainly used, the image having a high luminance by such a direct type The display panel 1 may be implemented.

By the way, the direct type as described above has the advantage that it can supply a large amount of light evenly to the front of the liquid crystal display panel (1), but the number of lamps used in the large area liquid crystal display device should increase Therefore, power consumption should increase accordingly. Therefore, methods for reducing power consumption in the direct type backlight unit have been continuously studied, and a scan driving method has been proposed.

The scan driving method does not turn on all lamps arranged to correspond to the front surface of the liquid crystal display panel 1, but sequentially turns on only a predetermined number of lamps, thereby reducing power consumption used to drive the lamps.

In the scan driving method, first, the driving frequency is set to 60 Hz, which is normally used, so that one frame is 16.7 ms. Scan signals are sequentially applied to the gate lines G1 to Gn arranged in the horizontal direction on the liquid crystal display panel 1 line by line from the gate driver 6. That is, the pixels connected to the gate lines G1 to Gn display images one line at a time.

However, the scan driving method has a problem in that the overall luminance is lower than that in the case where all the lamps are turned on. Therefore, a method of compensating for the decrease in luminance by increasing the amount of light in the lamp by increasing the amount of tube current supplied to the lit lamp has been used. However, since the maximum allowable current is determined for the lamp, when a tube current exceeding the maximum allowable current is supplied, reliability of the lamp cannot be secured, such as the service life of the lamp is drastically reduced.

In addition, when a high tube current is supplied for luminance compensation, a phenomenon occurs in which mercury, which is provided in the lamp and participates in the amount of light of the lamp, is concentrated on one side, and the lamp may emit light with irregular density, and the light discolors. May diverge. That is, it may adversely affect the reliability of the lamp and the image quality of the liquid crystal display.

SUMMARY OF THE INVENTION The present invention provides a liquid crystal display device driving circuit and a method of driving the same, which analyzes the brightness of image data and generates a brightness control signal according to the brightness to drive lamps, thereby reducing unnecessary power consumption and extending lamp life. There is this.

In addition, the present invention sets a plurality of divided regions per unit frame, analyzes the luminance for each divided region, generates a luminance control signal according to the luminance, and drives the lamp, thereby enabling more precise brightness adjustment. Another object is to provide a liquid crystal display driving circuit and a driving method thereof.

In order to achieve the above object, the liquid crystal display device driving circuit according to the present invention,

A liquid crystal display panel;

A gate driver and a data driver supplying a driving voltage and a data signal to the liquid crystal display panel;

A backlight unit including lamps for supplying a light source to the liquid crystal display panel, and an inverter for controlling the lamps;

A timing controller including an AI calculator configured to generate control signals for controlling the inverter from R, G, and B video signals applied from the outside; And

And a DC-DC converter for outputting a driving voltage, a gate low voltage signal VGL, and a gate high voltage signal VGH required for each part.

According to another embodiment of the present invention,

Setting at least one segmented area per image frame from R, G, and B video signals input from the outside;

Generating an inverter control signal for each of the divided regions; And

And controlling lamp brightness in units of a divided area by using the control signals.

Here, the step of generating the inverter control signal,

Counting a luminance value from a video signal corresponding to the divided region;

And converting the counted luminance values into a control signal using a lookup table stored in an external memory.

According to the present invention, the luminance of the image data is analyzed and the luminance control signal is generated according to the luminance to drive the lamps, thereby reducing unnecessary power consumption and extending the lamp life.

In addition, the present invention sets up a plurality of divided regions per unit frame, analyzes the luminance for each divided region, generates a luminance control signal according to the luminance, and drives the lamp, thereby enabling more precise brightness adjustment. .

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

2 is a view showing the structure of a liquid crystal display device having an adaptive brightness increasing function according to the present invention.

Referring to FIG. 2, a plurality of gate lines G and data lines D are arranged in a direction perpendicular to each other to have a matrix-type pixel region, and a liquid crystal display panel 11. It is divided into a driving circuit unit 12 for supplying a driving signal and a data signal.

Here, the driving circuit unit 12 may include a lookup table for storing a backlight dimming control signal value and data stretching values for adaptive luminance increase in each of a plurality of divided regions per unit frame. An external memory (EEPROM) 25 in which Up Table (LUT) is stored, and a voltage is applied to the system through the connector 22 to increase or decrease the voltage, thereby outputting driving voltages (Vcc, Vdd) necessary for each part, and a timing controller. The DC-DC converter 24 outputs the gate low voltage signal VGL and the gate high voltage signal VGH according to the operation signal of 23, and a look-up table of the external storage unit 25 when the power is turned on. A timing control for generating a plurality of control signals corresponding to the divided region from the built-in adaptive brightness intensifier (AI) operator 31 and outputting an operation signal for the operation of the DC-DC converter 24. A scan pulse is generated by receiving the gate high voltage signal VGH and the gate low voltage signal VGL output from the DC-DC converter 24 by the roller 23 and the operation signal of the timing controller 23. The gate driver 11a sequentially supplies scan pulses to the gate lines G of the liquid crystal display panel 11, and receives the corrected video signal Do output from the timing controller 23. And a data driver 11b for converting the corrected video signal into an analog corrected data signal and supplying the corrected data signal to each data line D of the liquid crystal display panel 11. have.

Here, the AI calculator 31 divides the video data signal input from the system into a plurality of areas per unit frame, compares the luminance values in each of the divided areas, and then stores the same in the external storage unit 25. A plurality of inverter 34 control signals Vbr1, Vbr2, Vbr3, and Vbr4 are generated according to the lookup table stored in the table. In the present invention, a description is made of a horizontal 4-division per unit frame, but the present invention is not limited thereto, and may be divided into a plurality of divided regions and a plurality of inverter control signals may be generated.

On the other hand, the timing controller 23 inputs the drive voltage and outputs an operation signal to the power control generating logic unit 32 and the checksum for the data of the lookup table stored in the external storage unit I2C. When communicating by reading in a protocol manner, the apparatus further includes a protocol unit 33 for providing the communication protocol I2C.

In addition, two active wires MSCL and MSDA for the communication are connected between the protocol unit 33 and the external storage unit 25.

Here, the AI calculator 31 further includes a backlight lamp 35 and an inverter 34 that operate according to control signals for controlling lighting of lamps per divided region of the image frame. The AI calculator 31 generates control signals corresponding to lamp brightness values for each divided region of the image frame, and these control signals are supplied to the inverter 34 to control the backlight lamps 35 in divided region units. do.

The AI calculating unit 31 divides the input image data into four divided regions per unit frame, and analyzes the luminance of each divided region. In general, image data is applied in the form of an RGB signal including red, green, and blue image information. The image data is expressed as a YUV signal composed of a luminance signal (Y) and a color difference signal (U, V). The dual luminance signal Y is detected and compared. The luminance variation for each divided area is compared every frame, and then the control signals Vbr1, Vbr2, Vbr3, and Vbr4 are converted from the lookup table stored in the external storage unit 25.

The control signals Vbr1, Vbr2, Vbr3, and Vbr4 are supplied to the inverter 34, and the backlight lamps 35 are lighted by mixing the adaptive luminance increasing method and the scanning method in each divided area unit.

Accordingly, in the present invention, the unit image frame is divided into a plurality of divided regions, and each of the divided regions is driven by an adaptive luminance increasing method and a scanning method, thereby achieving an image having a more precise contrast ratio.

3 is a diagram illustrating a state in which a control signal is generated for driving a multi-segmented backlight unit according to the present invention.

Referring to FIG. 3, the control signals of the inverter 34 in the horizontal 4-division region per unit frame centered on the external storage unit 25 and the AI calculating unit 31 disposed in the liquid crystal display driving circuit unit 12 are described. Vbr1, Vbr2, Vbr3, Vbr4) are generated.

R, G, and B video data (Image / Control Data) from the system is applied to the timing controller 23 of the driving circuit section 12 of the liquid crystal display device. The R, G, and B video data are converted and supplied so that an image can be displayed on the LCD panel by the timing controller 23. At this time, the AI calculating unit 31 supplies the R, G, B supplied from the system. After the video data signal is divided into four horizontal units per unit frame, the luminance of each divided area is compared to generate inverter 34 control signals Vbr1, Vbr2, Vbr3, and Vbr4. The inverter 34 control signals Vbr1, Vbr2, Vbr3, and Vbr4 correspond to luminance values obtained by the AI calculating unit 31 for each of the four horizontal division regions in the range between the maximum voltage Vmax and the minimum voltage Vmin. Voltage values are specified. In this case, the voltage corresponding to the luminance value obtained by the AI calculator 31 is determined through a lookup table stored in the external memory 25.

In general, the adaptive luminance increasing driving method separates luminance signals from R, G, and B video data per unit frame, and counts bright and dark luminance components for each of the separated R, G, and B video data. And then compare. When the value of the counted luminance components indicates a bright gray level (about 70% per frame), the luminance of the lamp is increased by increasing the lamp driving voltage of the backlight unit. On the contrary, when the gray scale is displayed, the lamp driving voltage of the backlight unit is normally maintained, and the gray scale voltage applied to the liquid crystal display panel is adjusted to control the luminance level to be darker.

In the present invention, the AI calculation unit 31 performs horizontal division per unit frame and separates luminance signals from R, G, and B video data for each divided region according to the adaptive luminance increasing driving method. For each of the R, G, and B video data, a bright luminance component and a dark luminance component are respectively counted and compared.

Therefore, by generating the lamp driving voltage (Vbr1, Vbr2, Vbr3, Vbr4) for each of the four divided regions per unit frame, the adaptive luminance increase driving and the scan driving in each divided region unit at the same time for more precise brightness control I could do it.

That is, the inverter control signals Vbr1, Vbr2, Vbr3, and Vbr4 generated from the AI calculating unit 31 are supplied to the inverter 34 together with the V-sync signal applied during the scanning driving so that the lamps are divided into units of each region. By driving it, more clear images can be realized.

In the present invention, the unit image frame is divided into four horizontal sections, but the present invention is not limited thereto, and lamp driving may be performed by dividing the unit image frame into a plurality of divided regions. For example, the unit image frame may be divided by the number of lamps used in the backlight unit, and the respective inverter control signal values may be calculated to drive the lamps.

4 is a diagram illustrating a driving state of a lamp using a multi-division backlight control signal generated from an adaptive luminance increasing circuit according to the present invention.

As shown in FIG. 4, the AI calculating unit 31 includes a control unit 55 and an AI circuit unit 50, and the AI circuit unit 50 includes R, G, B, and video data signals to correspond to four horizontal divisions. The first, second, third, and fourth comparators 60a, 60b, 60c, and 60d for counting and comparing the high and low luminance components with respect to the first, second, third, and fourth comparators 60a, Each of the first, second, third, and fourth conversion calculation units 70a, 70b, 70c, 70d converts the control signal of the inverter 34 on the basis of the luminance values obtained by the comparator corresponding to each of 60b, 60c, 60d. .

The first, second, third, fourth, and calculating units 70a, 70b, 70c, and 70d are external to the comparison values obtained from the first, second, third, and fourth comparison units 60a, 60b, 60c, and 60d, respectively. The inverter 34 control signals Vbr1, Vbr2, Vbr3, and Vbr4 are converted from the lookup table stored in the storage unit 25 to generate them. When the voltage range of the control signals is from 3.3 V maximum to 0.3 V minimum, the lookup table stored in the external storage unit 25 sets the respective voltages according to the ratio of luminance values counted by the comparator within the voltage range.

For example, the lookup table sets a maximum voltage of 3.3V when the high luminance component of the divided region is greater than or equal to 70% from the comparison value obtained by the first comparator 60a, and compares the result obtained by the second comparator 60b. When the high luminance component of the divided region is 50% in the value, 2V is set, and voltage values are set according to the comparison values obtained by the third and fourth comparators 60c and 60d, respectively. That is, control signal values are set according to the luminance component ratio included in each divided area.

As such, the control signals Vbr1, Vbr2, Vbr3, and Vbr4 obtained from the AI calculator 31 are supplied to the control IC 80 of the inverter 34.

The control IC 80 drives the lamps included in the respective divided regions according to the control signals Vbr1, Vbr2, Vbr3, and Vbr4.

In the figure, since eight lamps are divided into four horizontal sections, the first lamp 81a and the second lamp 81b are turned on by operating the first driver 81a and the second driver 81b according to the Vbr1 control signal. For example, as described above, when the luminance component of the first divided region is 70% or more and the control signal voltage is 3.3V, the first and second lamps lamp1 and lamp2 are driven to scan the maximum luminance value. Drive to generate

In the same manner, the third driving part 81c, the fourth driving part 81d, and the third and fourth lamps lamp3 and lamp4 are turned on using the Vbr2 control signal corresponding to the second divided area, and the third divided area is turned on. The fifth driving unit 81e, the sixth driving unit 81f, and the fifth and sixth lamps lamp5 and lamp6 are turned on by using the corresponding Vbr3 control signal, and the fifth driving unit 81e and the fifth and sixth lamps lamp5 and lamp6 are turned on. The seventh drive section 81g, the eighth drive section 81h, and the seventh and eighth lamps lamp7 and lamp8 are turned on.

According to the present invention, after dividing into a plurality of divided regions per image frame, inverter variable control signals are generated according to the luminance characteristics of each divided region, so that the scan driving and the adaptive luminance enhancement driving are performed in each divided region unit. It works.

As described in detail above, the present invention analyzes the brightness of the image data and generates a brightness control signal according to the brightness to drive the lamps, thereby reducing the unnecessary power consumption and extending the lamp life.

In addition, the present invention sets a plurality of divided regions per unit frame, analyzes the luminance for each divided region, generates a luminance control signal according to the luminance, and drives the lamp, thereby enabling more precise brightness adjustment. It works.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

Claims (9)

A liquid crystal display panel; A gate driver and a data driver supplying a driving voltage and a data signal to the liquid crystal display panel; A backlight unit including lamps for supplying a light source to the liquid crystal display panel, and an inverter for controlling the lamps; A timing controller including an AI calculator configured to generate control signals for controlling the inverter from R, G, and B video signals applied from the outside; And A liquid crystal display driving circuit comprising a DC-DC converter for outputting a driving voltage, a gate low voltage signal VGL, and a gate high voltage signal VGH necessary for each part. The liquid crystal display driving circuit of claim 1, further comprising an external storage unit including a look-up table that designates voltages for the inverter control signals. The apparatus of claim 1, wherein the AI calculator comprises: a controller configured to separate the R, G, and B video signals into a plurality of divided regions per image frame; And And an AI circuit unit configured to generate the inverter control signals corresponding to the divided region divided by the controller. 4. The liquid crystal display driving circuit of claim 3, wherein the AI circuit unit comprises at least one comparison unit corresponding to a divided region, and at least one conversion unit converting a control signal based on a value counted by the comparison unit. The liquid crystal display driving circuit of claim 1, wherein the inverter further comprises a control IC configured to adjust lighting of the lamps according to a control signal generated by the AI calculator. Setting at least one segmented area per image frame from R, G, and B video signals input from the outside; Generating an inverter control signal for each of the divided regions; And And controlling lamp brightness in units of a divided area by using the control signals. The method of claim 6, wherein generating the inverter control signal comprises: Counting a luminance value from a video signal corresponding to the divided region; And converting the counted luminance values into a control signal using a lookup table stored in an external memory. The method of claim 6, wherein generating the inverter control signal comprises: And an adaptive luminance increasing method for generating lamp control signals according to luminance characteristics of each of the divided regions. 7. The method of claim 6, wherein the lamps corresponding to the respective divided regions are turned on in a scan driving method according to the inverter control signal.

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