KR100785667B1 - Method for adjusting transmittance according to grayscale voltage and gamma voltage generation unit of display device using the same - Google Patents

Abstract

A method for adjusting transmittance of gray scale voltages and a gamma voltage generation unit of a display device using the same are provided to improve image quality by displaying natural color in a moving picture or an intermediate color using a small LCD(Liquid Crystal Display) module. Plural gamma reference voltages of which a slope and an amplitude are adjusted in response to register values from slope and amplitude adjustment registers. Plural gamma reference voltages are selected from the plural gamma reference voltages having the adjusted slope and amplitude in response to the register values from a fine adjustment register, and outputs the selected gamma reference voltages. Plural gamma voltages are generated in response to the gamma reference voltages. Transmittance by gray scale voltage is measured based on the respective gamma voltages and display data(S10). To minimize difference between the measured value and a transmittance by gray scale voltage, at least one of register values of the slope, amplitude, and fine adjustment registers are adjusted(S20).

Description

Method for adjusting transmittance according to grayscale voltage and gamma voltage generation unit of display device using the same}

The detailed description of each drawing is provided in order to provide a thorough understanding of the drawings cited in the detailed description of the invention.

1 is a block diagram of a display device capable of adjusting transmittance for each grayscale voltage according to an exemplary embodiment of the present invention.

FIG. 2 is a schematic block diagram of the gamma voltage generator shown in FIG. 1.

3 shows a target gamma curve having a measured gamma curve and a target gamma value.

4 shows the relationship between the gamma voltage and the gray voltage.

5 is a flowchart illustrating a method of controlling transmittance for each gray voltage according to an exemplary embodiment of the present invention.

The present invention relates to a gamma control method, and more particularly, to a method of controlling transmittance for each grayscale voltage capable of naturally expressing a color of an intermediate region, and a gamma voltage generator of a display device capable of adjusting transmittance for each grayscale voltage.

The gamma curve refers to a curve that normalizes transmittance for each gray voltage output from a source driver for driving data lines on an LCD panel. The gamma value also means the gradient of the linear region on the gamma curve, often referred to simply as gamma.

In general, when display data is displayed on an LCD panel, a person perceives an image represented by a gamma curve having a gamma value of 2.2 as the image having the highest quality.

Therefore, when the gamma value is adjusted in order to obtain a good image in the small LCD module including the LCD panel, the gamma value of white (or white gradation) is adjusted as one variable without adjusting each gamma value of RGB. It may not be natural to express the color of the middle region except full-white.

In addition, when the gamma values of RGB do not coincide with each other, a luminance difference occurs between RGB for each gray level, and thus, a color temperature deviation increases for each gray level. Therefore, when using the small LCD module to express the color of the moving picture or the middle region (for example, the color of the human skin), the small LCD module may not be able to express a natural image.

In addition, the small LCD module has a thickness issue. Instead of a top-view light source, a white light source is used as a filter by using a yellow phosphor in a side light source, that is, a blue light emitting device (LED) as a filter. Since the implementation method is used, there is a limit to increasing the color reproduction rate, which is a high quality standard. Therefore, the color to be displayed on the LCD panel is not properly represented, there is a problem that the quality of the image displayed on the LCD panel is degraded.

Therefore, there is a need for a method of increasing color reproducibility or image quality by using a small LCD module, and allowing a color of an intermediate region to be expressed naturally.

Therefore, the technical problem to be achieved by the present invention is to solve the above-mentioned problems, to provide a method for displaying a natural image when expressing the color of the moving picture or the middle region using a small LCD module.

In order to achieve the above technical problem, a method of controlling transmittance for each gray voltage may include measuring transmittance for each gray voltage generated by a plurality of gamma voltages and display data selected in response to a register value among a plurality of gamma reference voltages and measured gray levels. And adjusting at least one of the register values in order to minimize the difference between the transmittance for each voltage and the transmittance for each grayscale voltage of the target gamma value.

In order to achieve the above technical problem, a method of controlling transmittance for each gray voltage may include measuring transmittance for each gray voltage generated by a plurality of gamma voltages and display data selected in response to a register value among a plurality of gamma reference voltages and measured gray levels. And adjusting at least one of the register values to change each gamma voltage corresponding to the transmittance of each voltage into a gamma voltage corresponding to the transmittance of each of the gray scale voltages of the target gamma value.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

1 is a block diagram of a display device capable of adjusting transmittance for each gray voltage according to an exemplary embodiment of the present invention. Referring to FIG. 1, a display device 10 such as a flat panel display device may include a timing controller 20, a gamma voltage generator 30, a source driver 40, a gate driver 50, and a display panel 60. Include.

The timing controller 20 responds to the first data signals DATA1 which are display data output from a host such as a graphic controller (not shown) and the synchronization signal SYNC, and the second data signals DATA2 which are display data. ) And the first control signal TS1 are output to the source driver 40, and the second control signal TS2 is output to the gate driver 50. For example, the first control signal TS1 and the second control signal TS2 may be generated based on the synchronization signal SYNC.

The gamma voltage generator 30 generates a plurality of gamma voltages V0 to V63, and outputs the generated gamma voltages V0 to V63 to the source driver 40. For example, the gamma voltage generator 30 illustrated in FIG. 1 generates 64 gamma voltages V0 to V63.

The source driver 40 generates a plurality of data generated in response to the second data signals DATA2, the first control signal TS1, and the plurality of gamma voltages V0 to V63 output from the gamma voltage generator 30. The gray scale voltages of the output line are output to the display panel 60 through the data lines Y1 to Yn, where n is a natural number.

The gate driver 50 sequentially drives the plurality of gate lines G1 to Gm, where m is a natural number in response to the second control signal TS2.

The display panel 60 includes a plurality of data lines Y1 to Yn, a plurality of gate lines G1 to Gm, and a plurality of pixels. Accordingly, the display panel 60 displays an image corresponding to the first data signals DATA1 that are display data by using the plurality of pixels.

FIG. 2 is a block diagram of the gamma voltage generator shown in FIG. 1. Referring to FIG. 2, the gamma voltage generator 30 includes a control register 31, a gamma reference voltage generator 33, a gamma voltage selector 35, and a gamma voltage output unit 37.

The control register 31 is a tilt adjustment register 31-1 for storing register values for adjusting the slope of the gradation voltage relative to the number of gradations, and an amplitude adjustment register for storing register values for adjusting the amplitude of the gradation voltage relative to the gradation number. 31-2, and a fine adjustment register 31-3 for storing register values for finely adjusting the gradation voltage relative to the number of gradations.

The gamma reference voltage generator 33 is connected between the first terminal receiving the gamma power supply voltage VDD and the second terminal receiving the ground voltage VSS and generates a plurality of gamma reference voltages. The gamma reference voltage generator 33 includes a plurality of resistors connected in series between the first terminal and the second terminal, and the plurality of resistors include a plurality of fixed resistors and a plurality of variable resistors.

The gamma reference voltage generator 33 adjusts the slope and / or the amplitude in response to the register values output from the tilt adjustment register 31-1 and / or the register values output from the amplitude adjustment register 31-2. Generate gamma reference voltages.

The gamma voltage selector 35 includes a plurality of selectors (not shown), each of which selects a slope and / or an amplitude in response to the register values output from the fine adjustment register 31-3. The gamma reference voltages selected from the plurality of gamma reference voltages are output to the gamma voltage output unit 37.

The gamma voltage output unit 37 generates a plurality of gamma voltages V0 in response to the at least one gamma reference voltage output from the gamma reference voltage generator 33 and the gamma reference voltages output from the gamma voltage selector 35. Outputs ~ V63).

3 illustrates a target gamma curve having a measured gamma curve and a target gamma value, and FIG. 5 is a flowchart illustrating a method of controlling transmittance for each gray voltage according to an exemplary embodiment of the present invention.

Referring to FIG. 3, line L1 represents a gamma curve having a gamma value of 1.0, line L2 represents a gamma curve having a gamma value of 2.2, and line L3 represents an actually measured gamma curve.

1 and 3, the source driver 40 generates a plurality of gray voltages in response to the plurality of gamma voltages V0 to V63 and the display data DATA2 output from the gamma voltage generator 30. Are output to the display panel 60 through the data lines Y1 to Yn.

Therefore, the measuring device capable of measuring the transmittance of each gray voltage may measure the transmittance of each gray voltage. That is, the transmittance for each grayscale voltage generated by each of the plurality of gamma voltages V0 to V63 and the display data DATA2 selected in response to each of the register values among the plurality of gamma reference voltages is measured through the measuring apparatus (FIG. 5, S10).

As shown in FIG. 3, a difference occurs between the measured transmittance of each gray voltage and the transmittance of each gray voltage of the target gamma value 2.2. For example, the transmittance measured at the gradation voltage m is tm and the transmittance at the gradation voltage m with a target gamma value of 2.2 is tm '. Therefore, in order to improve the quality of the displayed image, it is necessary to change the transmittance tm measured at the gradation voltage m to the target transmittance tm '. The method of changing tm to tm 'will be described in detail with reference to FIGS. 3 and 4.

4 shows the relationship between the gamma voltage and the gray voltage. Referring to FIG. 4, the line L11 represents a relationship between the gamma voltage and the gray voltage for the measured transmittance for each gray voltage, and the line L12 corresponds to the transmittance for each gray voltage of the target gamma value (eg, 2.2). Shows the relationship between the gamma voltage and the gradation voltage.

3 and 4, the gray voltage corresponding to each of the gamma voltage Vm and the gamma voltage Vm 'is m, and the transmittance by the gray voltage m corresponding to the gamma voltage vm is tm and the gamma voltage. The transmittance by the gradation voltage m corresponding to (vm ') is tm'. Accordingly, when the gamma voltage vm corresponding to the gray voltage m is changed to the gamma voltage vm ', the transmittance measured at the gray voltage m may be changed from tm to tm'.

That is, at least one of register values stored in the tilt adjustment register 31-1 of the control register 31, register values stored in the amplitude adjustment register 31-2, or register values stored in the fine adjustment register 31-3. When the register value of is changed, the gamma voltage vm generated by the gamma voltage generator 30 will be changed to the gamma voltage vm '.

In this manner, each gamma voltage corresponding to the transmittance for each gray voltage measured based on the register values stored in the control register 31 is converted into a gamma voltage corresponding to the transmittance for each gray voltage of the target gamma value. When changing, the difference between the measured transmittance for each gray voltage and the transmittance for each gray voltage of the target gamma value may be substantially eliminated or minimized (S20 of FIG. 5). Each of the register values stored in the control register 31 may be set or changed using hardware or software.

The look-up table may be used to calculate a difference between the measured transmittance of each of the gray voltages and the transmittance of each of the gray voltages of the target gamma value. In addition, the look-up table may include a gamma voltage corresponding to the measured transmittance for each gray voltage and a gamma voltage corresponding to the transmittance for each gray voltage of the target gamma value.

For example, the measured gamma voltage includes a measured transmittance for each of the gray scale voltages, a transmittance for each gray voltage of the target gamma value, a gamma voltage corresponding to each measured transmittance for each gray voltage, and a gamma voltage corresponding to a transmittance for each gray voltage of the target gamma value. With reference to the look-up table, the difference between the measured transmittance for each gray voltage and the transmittance for each gray voltage of the target gamma value is calculated, and each of the register values stored in the control register 31 is minimized so that the differences can be minimized. You can change it. For example, each of the register values stored in the control register 31 may be changed automatically or manually using software or hardware.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the method of controlling transmittance for each gray voltage according to the present invention may more naturally express a color of a moving image or an intermediate region (for example, the color of human skin).

Therefore, there is an effect that can improve the quality of the image displayed on the LCD panel.

Claims (2)

Generating a plurality of tilt and amplitude adjusted gamma reference voltages in response to the register values output from the tilt adjustment register and the register values output from the amplitude adjustment register; In response to the register values output from the fine adjustment register, selecting a plurality of gamma reference voltages from the plurality of gradient and amplitude adjusted gamma reference voltages, and outputting the selected plurality of gamma reference voltages; Generating a plurality of gamma voltages in response to at least one of the plurality of tilt and amplitude adjusted gamma reference voltages and the selected plurality of gamma reference voltages; Measuring transmittance of each of the plurality of gamma voltages and the gray voltage generated by the display data; And In order to minimize the difference between the measured transmittance for each of the gray scale voltages and the transmittance for each of the gray scale voltages of the target gamma value, among register values stored in the gradient control register, register values stored in the amplitude adjustment register, and register values stored in the fine adjustment register. Transmittance control method according to the gray-level voltage comprising the step of adjusting at least one resistor value. A tilt adjusting register for storing register values for adjusting a slope of the gray voltage relative to the gray number; An amplitude adjustment register for storing register values for adjusting the amplitude of the gradation voltage relative to the gradation number; A fine adjustment register for storing register values for fine-adjusting the gray level voltage relative to the number of gray levels; A gamma reference voltage generator configured to generate a plurality of gradient and amplitude adjusted gamma reference voltages in response to the register values output from the tilt adjustment register and the register values output from the amplitude adjustment register; In response to the register values output from the fine adjustment register, a plurality of gamma reference voltages are selected from among the slope and amplitude adjusted gamma reference voltages generated by the gamma reference voltage generator, and the selected plurality of gamma reference voltages are selected. An output gamma voltage selector; And A gamma outputting a plurality of gamma voltages in response to at least one of the gradient and amplitude adjusted gamma reference voltages generated by the gamma reference voltage generator, and a plurality of gamma reference voltages selected by the gamma voltage selector A voltage output, Register values stored in the gradient adjusting register and register values stored in the amplitude adjusting register to change each gamma voltage corresponding to the measured transmittance of the grayscale voltage into a respective gamma voltage corresponding to the transmittance of the grayscale voltage of the target gamma value. And a gamma voltage generator of a display device capable of adjusting transmittance for each gray scale voltage at which at least one register value is changed among register values stored in the fine regulating register.

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