KR101139521B1 - Method and Apparatus for Driving Liquid Crystal Display Device - Google Patents

Abstract

The present invention relates to a driving device and a method of a liquid crystal display device.

An apparatus and method for driving a liquid crystal display according to an exemplary embodiment of the present invention improve image quality by processing image data input from the outside, and use an image quality improving unit to supply the timing controller and a signal supplied from the timing controller. It is characterized by comprising a liquid crystal panel for implementing an image.

Description

Driving apparatus and method of liquid crystal display device {Method and Apparatus for Driving Liquid Crystal Display Device}             

1 is a block diagram showing a driving device of a conventional liquid crystal display device.

2 is a block diagram illustrating a driving device of a liquid crystal display according to a first embodiment of the present invention.

3 is a block diagram illustrating an image quality improvement unit of FIG. 2.

4 is a diagram illustrating a threshold value according to the image quality improvement unit of FIG. 3.

5 is a block diagram illustrating an image quality improving unit of a driving device of a liquid crystal display according to a second exemplary embodiment of the present invention.

FIG. 6 is a diagram illustrating a threshold value according to the image quality improvement unit of FIG. 5.

<Description of Symbols for Main Parts of Drawings>

2, 22: liquid crystal panel 4, 24: data driver

6, 26: gate driver 8, 28: gamma voltage supply

10, 30: timing controller 12, 32: power supply

14, 34: DC / DC converter 16, 36: inverter                 

18, 38: backlight 20, 40: system

42: image quality improvement unit 52: luminance extraction unit

54: memory 56: sharpness mask

58: smoothing mask 60: calculation unit

62: luminance / color mixing unit 68: control unit

The present invention relates to a driving device and a method of a liquid crystal display device, and more particularly to a driving device and a method for improving the image quality.

In general, liquid crystal displays (hereinafter referred to as "LCDs") have tended to be increasingly wider in application due to features such as light weight, thinness, and low power consumption. According to this trend, LCDs are used for office automation equipment, audio / video equipment, and the like. On the other hand, the LCD is controlled to display the desired image on the screen by adjusting the transmission amount of the light beam according to the image signal applied to the plurality of control switches arranged in a matrix form.

1 schematically shows a driving device of a conventional liquid crystal display.

Referring to FIG. 1, in a driving apparatus of a conventional liquid crystal display, m × n liquid crystal cells Clc are arranged in a matrix type, m data lines D1 to Dm and n gate lines G1 to A liquid crystal panel 2 having Gn intersected and a TFT formed at an intersection thereof, a data driver 4 for supplying a data signal to the data lines D1 to Dm of the liquid crystal panel 2, and gate lines. The gate driver 6 for supplying the scan signal to the G1 to Gn, the gamma voltage supply unit 8 for supplying the gamma voltage to the data driver 4, and the synchronization signal supplied from the system 20 are used. To generate the voltages supplied to the liquid crystal panel 2 by using the timing controller 10 for controlling the data driver 4 and the gate driver 6 and the voltage supplied from the power supply 12. DC conversion unit (hereinafter referred to as "DC / DC conversion unit") 14, and The byte 18 comprises an inverter 16 for driving.

The system 20 supplies the vertical / horizontal synchronization signals Vsync and Hsync, the clock signal DCLK, the data enable signal DE and the data R, G, and B to the timing controller 10.

The liquid crystal panel 2 includes a plurality of liquid crystal cells Clc disposed in a matrix at the intersections of the data lines D1 to Dm and the gate lines G1 to Gn. Each TFT formed in the liquid crystal cell Clc supplies a data signal supplied from the data lines D1 to Dm to the liquid crystal cell Clc in response to a scan signal supplied from the gate line G.

The gamma voltage supply unit 8 supplies a plurality of gamma voltages to the data driver 4.

The data driver 4 converts the digital video data R, G, and B into analog gamma voltages (data signals) corresponding to the gray scale values in response to the control signal CS from the timing controller 10. The gamma voltage is supplied to the data lines D1 to Dm.

The gate driver 6 sequentially supplies scan pulses to the gate lines G1 to Gn in response to the control signal CS from the timing controller 10 so that the data signal is supplied horizontally. Select a line.

The timing controller 10 uses a control signal for controlling the gate driver 6 and the data driver 4 by using the vertical / horizontal synchronization signals Vsync and Hsync and the clock signal DCLK input from the system 20. Generate CS). The control signal CS for controlling the gate driver 6 includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable (GOE), and the like. Included. The control signal CS for controlling the data driver 4 includes a source start pulse (SSP), a source shift clock (SSC), a source output signal (SOE), and Polarity signal (POL) is included. The timing controller 10 rearranges the data R, G, and B supplied from the system 20 and supplies the data driver 4 to the data driver 4.

The DC / DC converter 14 boosts or reduces the voltage of 3.3V input from the power supply 12 to generate the voltage supplied to the liquid crystal panel 2. The DC / DC converter 14 generates a gamma reference voltage, a gate high voltage VGH, a gate low voltage VGL, a common voltage Vcom, and the like.

The inverter 16 supplies a driving voltage (driving current) for driving the backlight 18 to the backlight 18. The backlight 18 generates light corresponding to a driving voltage (or driving current) supplied from the inverter 16 and supplies the light to the liquid crystal panel 2.

In order to display the vivid image in the liquid crystal panel 2 driven as described above, the contrast between the bright image and the dark image should be clear. However, in the conventional liquid crystal display device, since there is no method for extending the contrast in response to data, it is difficult to display a vivid image.

Accordingly, it is an object of the present invention to provide a driving apparatus and method for a liquid crystal display device capable of improving image quality.

In order to achieve the above object, a driving apparatus of a liquid crystal display according to an embodiment of the present invention includes a luminance extracting unit for extracting the luminance component of the data input from the outside; At least two brightness varying units for varying brightness components from the brightness extracting unit to generate at least two brightness varying signals; A calculator which compares each of the at least two luminance variable signals with a luminance component from the luminance extractor, and selects and outputs one of them; And a memory for storing the extracted luminance components and supplying the at least two luminance variable units and the calculation unit.

The at least two luminance variable parts include at least one first luminance variable part for extending a contrast ratio of the luminance component from the luminance extracting part; And a second luminance variable portion for reducing the contrast ratio of the luminance component from the luminance extracting portion.

The calculating unit outputs a luminance component from the luminance extracting unit when the first luminance variable signal output from the at least one first luminance variable unit is larger than a first threshold value arbitrarily set using the extracted luminance component, When the first luminance variable signal output from the at least one first luminance variable portion is smaller than a second threshold arbitrarily set using the extracted luminance component, the second luminance variable signal output from the second luminance variable portion is changed. Output

The driving device of the liquid crystal display device comprises: a timing controller for rearranging data output from the calculation unit; And a data driver for supplying the second data rearranged from the timing controller to the data line of the liquid crystal panel.

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A method of driving a liquid crystal display device according to the present invention comprises the steps of: extracting a luminance component from first data input from the outside and storing the extracted luminance component in a memory; Generating at least two luminance variable signals by varying the extracted luminance components; Comparing each of the at least two luminance variable signals with the extracted luminance component using a calculator and selecting and outputting any one of them; And supplying data output from the calculator to a liquid crystal panel that implements an image.

Generating at least two luminance variable signals by varying the extracted luminance component; Generating at least one first luminance variable signal using at least one first luminance variable unit for extending the contrast ratio of the extracted luminance component; Generating a second luminance variable signal by using a second luminance variable unit which reduces the contrast ratio of the extracted luminance component.                     

Comparing each of the at least two luminance variable signals with the extracted luminance component using the calculator and selecting and outputting any one of them; And comparing the at least one first luminance variable signal, the second luminance variable signal, and the extracted luminance component with each other by using the calculator.

Comparing each of the at least two luminance variable signals with the extracted luminance component by using a calculator and selecting and outputting any one of them; Outputting the extracted luminance component when the at least one first variable signal is greater than a first threshold value arbitrarily set using the extracted luminance component; And outputting the second variable signal when the at least one first variable signal is smaller than a second threshold value arbitrarily set using the extracted luminance component.

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

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

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

Referring to FIG. 2, in the driving apparatus of the liquid crystal display according to an exemplary embodiment of the present invention, m × n liquid crystal cells Clc are arranged in a matrix type, m data lines D1 to Dm and n gates are provided. The liquid crystal panel 22 in which the lines G1 to Gn cross and the TFT is formed at the intersection thereof, and the data driver 24 for supplying data signals to the data lines D1 to Dm of the liquid crystal panel 22. ), A gate driver 26 for supplying a scan signal to the gate lines G1 to Gn, a gamma voltage supply unit 28 for supplying a gamma voltage to the data driver 24, and a system 40 from the system 40. The voltage supplied to the liquid crystal panel 22 using the timing controller 30 for controlling the data driver 24 and the gate driver 26 by using the supplied synchronization signal, and the voltage supplied from the power supply unit 32. DC / DC converter for generating sound ("DC / D The luminance component at the boundary of the first data Ri, Gi, and Bi supplied from the system 40, the inverter 36 for driving the backlight 38, and the " C converter &quot; After extracting and processing, the image quality improving unit 42 improves the image quality by outputting the selected value by comparing the processed data with the luminance component of the original image, and the second data (output from the image quality improving unit 42) The control unit 68 is configured to supply a control signal corresponding to R0, G0, B0 to the timing controller 30.

The system 40 supplies the vertical / horizontal synchronization signals Vsync and Hsync, the clock signal DCLK, the data enable signal DE and the data R, G, and B to the image quality improvement unit 42.

The liquid crystal panel 22 includes a plurality of liquid crystal cells Clc disposed in a matrix at the intersections of the data lines D1 to Dm and the gate lines G1 to Gn. Each TFT formed in the liquid crystal cell Clc supplies a data signal supplied from the data lines D1 to Dm to the liquid crystal cell Clc in response to a scan signal supplied from the gate line G.

The gamma voltage supply unit 28 supplies a plurality of gamma voltages to the data driver 24.

The data driver 4 converts the digital video data R, G, and B into analog gamma voltages (data signals) corresponding to the gray scale values in response to the control signal CS from the timing controller 30. The gamma voltage is supplied to the data lines D1 to Dm.

The gate driver 26 sequentially supplies scan pulses to the gate lines G1 to Gn in response to the control signal CS from the timing controller 30 to supply a horizontal signal to the liquid crystal panel 22. Select.

The timing controller 30 uses control signals for controlling the gate driver 26 and the data driver 24 using the vertical / horizontal synchronization signals Vsync and Hsync and the clock signal DCLK input from the system 40. Generate CS). The control signal CS for controlling the gate driver 26 includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable (GOE), and the like. Included. The control signal CS for controlling the data driver 24 includes a source start pulse (GSP), a source shift clock (SSC), a source output signal (SOC), and Polarity signal (POL) is included. The timing controller 30 rearranges and supplies the second data R0, G0, and B0 supplied from the image quality improvement unit 42 to the data driver 4.

The DC / DC converter 34 generates a voltage supplied to the liquid crystal panel 22 by boosting or reducing the voltage input from the power supply unit 32. The DC / DC converter 34 generates a gamma reference voltage, a gate high voltage VGH, a gate low voltage VGL, a common voltage Vcom, and the like.                     

The inverter 36 supplies a driving voltage (driving current) for driving the backlight 38 to the backlight 38. The backlight 38 generates light corresponding to the driving voltage (or driving current) supplied from the inverter 36 and supplies the light to the liquid crystal panel 22.

Referring to FIG. 3, the image quality improvement unit 42 stores a luminance extracting unit 52 for extracting a luminance component from first data Ri, Gi, and Bi supplied from the system 40, and the extracted luminance component. Memory 54, a sharpness mask 56 for extending the contrast ratio of each luminance component stored in the memory 54, and contrast for smoothly expressing each luminance component stored in the memory 54. Comparing / selecting a difference between a smoothing mask 58 for reducing the summation, a difference between the luminance component output from the sharpness mask 56, the luminance component output from the smoothing mask 58, and the luminance components stored in the memory. The calculator 60 and a luminance mixer 62 for converting the selected luminance component into second data R0, G0, B0 and supplying the same to the timing controller 30 are provided.

The luminance extracting unit 52 separates the first data Ri, Gi, and Bi into luminance components Y and color difference components U and V by using Equations 1 to 3 below.

Y = 0.229 x Ri + 0.587 x Gi + 0.114 x Bi

U = 0.493 × (Bi-Y)

V = 0.887 × (Ri-Y)

The memory 54 stores a predetermined amount of luminance components extracted from the luminance extraction unit 52. Here, the size of the memory 52 may vary variably depending on the requirements of the system. This memory 52 is stored for sharpening and smoothing of image data.

The variable portion, that is, the brightness mask 56, which varies the luminance by expanding the contrast ratio of the luminance component, stores the image data stored in the memory 52 in four parameters, namely, Amount, Radius, Thresholds and multipliers are used to increase sharpness at the interface. Here, the amount is an indicator indicating how deep the gray at the boundary surface is to be highlighted, and the radius is an indicator indicating how wide the area of the boundary is to be emphasized. In addition, the threshold value indicates whether the range in which sharpness is executed is to be performed in all gray areas or only in a certain portion. A multiplier is a constant value that calculates a decimal point, multiplies an integer, and divides it by the final product. The larger the constant value of the multiplier is, the more precisely it is calculated and the sharper the image can be.

Let us look at the sharpness method by the derivative for the sharpness mask 56 design.

The sharpness method based on the derivative is an edge detect method, which detects the boundary region in the image in the image through the first derivative as shown in Equation 4.

dA / dx = ΔA (X) = X (i + 1)-X (i) → B = [-1, 1]

After detecting the boundary surface in the image, a substantially boundary surface is detected in the boundary region by the second derivative as shown in Equation 5.

d ² A / dx ² = ΔA (X (i + 1))-ΔA (X (i))

= X (i + 2)-X (i + 1)-(X (i + 1)-X (i))

= X (i + 2)-2X (i + 1) + X (i) → B = [1, -2, 1]

When the resulting value of Equation 5 is negative and summed with the original boundary, the lower gray level is converted to the lower gray level at the boundary, and the higher gray level is converted higher to contrast at the boundary. Can improve rain. Extending this sharpness method to two dimensions is shown in Equation 6 and Table 1.

d ² A / d ² (x, y) = d ² A / d ² x + d ² A / d ² y

Here, when summed with the original image to improve the contrast ratio at the interface, it is shown in Table 1.

A (x, y)-d ² A / d ² (x, y) = 0 -One 0 -One 5 -One 0 -One 0

org (x, y) =

M11 M12 M13 M21 M22 M23 M31 M32 M33

Where org (x, y) * A (x, y) = M22-M12-M21-M23-M32.

Next, a method of generating the sharpness mask 52 using the three-dimensional model of the sharpness mask will be described.

The sharpness three-dimensional mask can be expressed as follows.

In the sharpness three-dimensional mask generation method, first, multiply each factor by a multiplier as shown in Equation 7 to calculate an integer.

Bij = aij * multiplier

Where i, j = 0, 1, 2.

Then, in the two-dimensional discrete form, the normal distribution between the factors is made through the standard normal distribution shown in Equation (8).

Cij = Bijexp (-(x2 + y2) / 2r2)

Where r is the radius.                     

In Equation 8, as the size of r increases, the spread becomes larger, and the sharpness spread on the interface becomes larger when the sharpness is executed.

Next, each of the factors is divided by the sum of all the factors of the matrix as shown in Equation 9 to meet the original data.

Dij = Cij / (a00 + a01 + ... + a22)

Then, the sharpness depth is adjusted by multiplying the quantity having a specific number as shown in Equation 10.

Eij = Dij * quantity / 100

Finally, after inverting the result as -Eij, org (x, y) is added to the center value and divided by the first multiplier to form a sharp three-dimensional mask.

The variable portion, i.e., the smoothing mask 58, which varies the luminance by reducing the contrast ratio of the luminance component, is designed with three parameters: radius, threshold and multiplier. Here, the radius is an index for setting the smoothing, that is, the range in which the image is smoothly expressed, and the threshold is an index for setting the on / off of smoothing. In addition, the multiplier is a constant used to multiply a number to calculate an integer, and divide it again after the calculation. As in the sharpness mask 56, the size of the multiplier determines the precision of the calculation.

Here, the method of generating the smoothing mask 58 by using the three-dimensional model of the smoothing mask 58 will be described.                     

The three-dimensional model of the smoothing mask 58 is similar to the three-dimensional model of the sharpness mask 56.

It can be expressed as

The method of generating the smoothing mask 58 is generated in the same manner except that the value is inverted in the last step compared to the method using the three-dimensional model of the sharpness mask 56, and thus description thereof will be omitted.

The calculation unit 60 performs sharpness data SH of processing image data stored in the memory 52 using the sharpness mask 56 and smoothing data SM of processing image data using the smoothing mask 58. And a luminance component difference between the original image data OMs. Thereafter, as shown in FIG. 4, when the luminance component difference is greater than or equal to a predetermined upper threshold value, the original image data OM is selected and output. When the luminance component difference is less than or equal to the lower threshold value, the smoothing data SM is selectively output. At this time, when the luminance component difference is located between the upper threshold value and the lower threshold value, the sharpness data SM is output.

The luminance / color mixing unit 62 generates the second data R0, G0, and B0 by using the modulated luminance component YM and the delayed color difference components UD and VD. Here, the second data (R0, G0, B0) is obtained by the equations (11) to (13).

R0 = Y + 0.000 × U + 1.140 × V

G0 = Y-0.396 × U-0.581 × V

B0 = Y + 2.029 × U + 0.000 × V

The controller 68 receives the first vertical / horizontal synchronization signals Vsync1 and Hsync1, the first clock signal DCLK1, and the first data enable signal DE1 input from the system 40. In addition, the controller 68 may synchronize the second vertical / horizontal synchronization signals Vsync2 and Hsync2, the second clock signal DCLK2, and the second data enable signal DE2 to be synchronized with the second data Ro, Go, and Bo. Is generated and supplied to the timing controller 30.

A driving method of the liquid crystal display device according to the first embodiment of the present invention having such a structure will be described.

In the driving method of the liquid crystal display according to the first exemplary embodiment of the present invention, first, first, the first data Ri, Gi, and Bi of the luminance extracting unit 52 of the image quality improving unit 42 are supplied from the system 40. The luminance component is extracted from the image, and the extracted luminance component is stored using the memory 54. Thereafter, the sharpness mask 56 and the smoothing mask 58 process the contrast of the luminance component stored in the memory 54 to output the sharpness data SH and the smoothing data SM, respectively. Next, the calculator 60 compares the data SH and SM output from the masks 56 and 58 with the original image data OM to output the selected image data. Finally, the image data output from the calculator 60 is converted into the second data using the luminance / color mixing unit 62 and then supplied to the timing controller 30. The liquid crystal panel 22 receives the rearranged second data R0, G0, and B0 from the timing controller 30 to implement an image.

On the other hand, the driving device of the liquid crystal display device according to the second embodiment of the present invention is compared with the driving device of the liquid crystal display device according to the first embodiment of the present invention shown in FIG. Since the same components are provided except for the sharpness masks Sh1 to Sh3, the description of the components will be omitted.

The driving apparatus of the liquid crystal display according to the second exemplary embodiment of the present invention subdivids each threshold as shown in FIG. 6 to provide a clearer image in an image having many interfaces.

Referring to FIG. 6, a plurality of sharpness masks Sh1 to Sh3 of the driving apparatus of the liquid crystal display according to the second embodiment of the present invention are compared with the sharpness mask 52 described in the first embodiment of the present invention. By operating the threshold in a limited manner, the method of generating a plurality of sharpness masks Sh1 to Sh3 of the driving apparatus of the liquid crystal display according to the second embodiment of the present invention will be omitted. Shall be. Thresholds of the sharpness masks Sh1 to Sh3 may be divided in a biased manner according to an image. For example, when the gray scale value is divided between 80 and 200 based on an image having 0 to 255 gray scales using three sharpness masks Sh1 to Sh3, the first sharpness mask Sh1 is 80 to 110 degrees. The gray scale value, the second sharpness mask Sh2 may use the gray scale value of 110 to 180, and the third sharpness mask Sh3 may use the gray scale value of 180 to 200 as its threshold value, respectively. In addition, the driving apparatus of the liquid crystal display according to the second exemplary embodiment of the present invention is not limited to the number of sharpness masks Sh1 to Sh3.

As described above, the driving apparatus of the liquid crystal display according to the exemplary embodiment of the present invention compares the image processed by the sharpness mask and the smoothing mask with the original image data. Thereafter, by selectively outputting an image having better image quality, the image has excellent utility in image quality improvement. Accordingly, the driving device of the liquid crystal display according to the exemplary embodiment of the present invention can solve the problem of the image overlapping and the image quality being roughly expressed in the image having many characters or boundaries.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

Claims (9)

A luminance extracting unit which extracts a luminance component of data input from the outside; At least two brightness varying units for varying brightness components from the brightness extracting unit to generate at least two brightness varying signals; A calculator which compares each of the at least two luminance variable signals with a luminance component from the luminance extractor, and selects and outputs one of them; And a memory for storing the extracted luminance components and supplying the extracted luminance components to the at least two luminance variable parts and the calculator. The method of claim 1, The at least two luminance variable unit At least one first luminance variable portion for extending the contrast ratio of the luminance component from the luminance extracting portion; And a second luminance variable portion for reducing the contrast ratio of the luminance component from the luminance extracting portion. The method of claim 1, The calculation unit Outputs a luminance component from the luminance extracting unit when the first luminance variable signal output from the at least one first luminance variable unit is larger than a first threshold value arbitrarily set using the extracted luminance component, When the first luminance variable signal output from the at least one first luminance variable portion is smaller than a second threshold arbitrarily set using the extracted luminance component, the second luminance variable signal output from the second luminance variable portion is changed. And a drive device for the liquid crystal display device. The method of claim 1, A timing controller for rearranging data output from the calculation unit; And a data driver for supplying the second data rearranged from the timing controller to a data line of the liquid crystal panel. delete Extracting a luminance component from the first data input from the outside and storing the extracted luminance component in a memory; Generating at least two luminance variable signals by varying the extracted luminance components; Comparing each of the at least two luminance variable signals with the extracted luminance component using a calculator and selecting and outputting any one of them; And supplying data output from the calculator to a liquid crystal panel for implementing an image. The method of claim 6, Generating at least two luminance variable signals by varying the extracted luminance component; Generating at least one first luminance variable signal using at least one first luminance variable unit for extending the contrast ratio of the extracted luminance component; And generating a second luminance variable signal by using a second luminance variable unit which reduces the contrast ratio of the extracted luminance component. The method of claim 7, wherein Comparing each of the at least two luminance variable signals with the extracted luminance component using the calculator and selecting and outputting any one of them; And comparing the at least one first luminance variable signal, the second luminance variable signal, and the extracted luminance component with each other by using the calculator to output each other. Way. The method of claim 8, Comparing each of the at least two luminance variable signals with the extracted luminance component using the calculator and selecting and outputting any one of them; Outputting the extracted luminance component when the at least one first variable signal is greater than a first threshold value arbitrarily set using the extracted luminance component; And outputting the second variable signal when the at least one first variable signal is smaller than a second threshold value arbitrarily set using the extracted luminance component.

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