KR20080072389A - Display appratus - Google Patents

Abstract

A display apparatus is provided to enhance the display quality of display device by minimizing the variation of gray scale color temperature value through an ACC(Accurate Color Capture) compensation. A display apparatus includes a signal controller(150), a color compensator(160), drivers(130,140), a display panel(210), and a beam generator(200). The signal controller outputs raw gray scale data in response to image signals supplied from an external image signal source. The color compensator extracts compensation gamma values from compensation signals inputted from outside, compensates for the raw gray scale data based on the extracted compensation gamma values, and outputs compensation gray scale data. The drivers receive the compensation gray scale data and output analog signals corresponding to the compensation gray scale data. The display panel displays images corresponding to the analog signals using white beams. The beam generator generates the white beams.

Description

 Display device {DISPLAY APPRATUS}

In order to more fully understand the drawings used in the detailed description of the invention, a brief description of each drawing is provided.

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

FIG. 2 is a diagram illustrating a configuration of the color compensator illustrated in FIG. 1.

3 is a diagram illustrating a configuration of the color temperature compensator shown in FIG. 1.

4 is a flowchart illustrating a method of driving a liquid crystal display according to the present invention.

FIG. 5 is a flowchart showing step A illustrated in FIG. 4 in detail.

6 is a graph showing the change in color temperature according to the gradation change after the CCT value change and before the ACC correction.

7 is a graph showing the change in color temperature according to the gradation change after ACC correction after changing the CCT value.

The present invention relates to a display device, and more particularly, to a display device capable of changing a color temperature value.

In general, the chromaticity of the light source or the reference white can be expressed as the temperature of the nearest point on the radial curve instead of the coordinates on the two-dimensional chromaticity diagram, which is referred to as a correlated color temperature (hereinafter referred to as 'CCT') or It is called color temperature. This color temperature is a useful figure indicating the bluish degree of white or the degree of white yellow.

When the display device expresses color, the higher the color temperature, the more blue color is included, and the lower the color temperature, the more red color is included. These characteristics of color temperature have different preferences in different countries.

On the other hand, the liquid crystal display device mainly uses a cold cathode fluorescent lamp as a light generating means, and therefore, to change the CCT, it is necessary to use a fluorescent lamp having a completely different specification without using a conventional fluorescent lamp.

Accordingly, it is an object of the present invention to provide a display device capable of changing the CCT value.

The display device of the present invention for achieving the above technical problem includes a signal controller, a color compensator, a driver, a display panel and a light generator. The signal controller outputs raw grayscale data in response to a video signal provided from an external video signal source. The color compensator receives a correction signal, extracts a correction gamma value from the correction signal, and corrects and outputs the raw grayscale data as corrected grayscale data based on the extracted correction gamma value. The driver outputs an analog signal corresponding to the correction grayscale data. The display panel displays an image corresponding to the analog signal using white light. The light generating unit generates the white light. The light generator includes a light detector, a light detector, a color temperature compensator, a light source driver, and a light source. The light detector detects a light amount of the white light. The light detector outputs a light detection signal corresponding to the detected light amount. The color temperature compensator corrects the color temperature value of the detected light amount in response to the light detection signal and generates the correction signal based on the corrected color temperature value. The light source driver outputs a drive signal based on the correction signal. The light source unit includes a plurality of light emitting diodes that generate light in response to the driving signal.

Preferably, each of the plurality of light emitting diodes may be composed of any one of red, green and blue light emitting diodes.

Also preferably, the color correction unit includes a gamma value extraction unit, a memory unit, and an ACC controller. A gamma value extractor extracts a correction gamma value from the correction signal. The first memory unit stores a plurality of grayscale values corresponding to the extracted correction gamma value. The ACC and the controller read out a plurality of grayscale values corresponding to the corrected gamma value in response to the corrected gamma value, and corrects and outputs the raw grayscale data as corrected grayscale data based on the read plurality of grayscale values.

As described above, the display device according to the present invention includes a color temperature compensator and a color compensator. The color temperature compensator changes the CCT value of the white light emitted from the light source unit based on the compensated color coordinate value, and outputs a correction signal including the compensated color coordinate value information to the color compensator. The color compensator performs ACC correction in response to the compensation signal.

According to the display device according to the present invention, by changing the CCT value using the LED backlight, it has the effect of standardization and cost reduction of the backlight. In addition, the present invention may improve the display quality of the display device by performing ACC correction after minimizing the CCT value, thereby minimizing the variation of the color temperature value for each gradation according to the changed CCT 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. In understanding the drawings, it should be noted that like parts are intended to be represented by the same reference numerals as much as possible. In addition, in the following description, numerous specific details, such as specific processing flows, are described to provide a more general understanding of the invention. Incidentally, detailed descriptions of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

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

1 is a block diagram showing the configuration of a liquid crystal display device 1000 according to the present invention.

Referring to FIG. 1, the liquid crystal display device 1000 includes a display unit 100 and a light generator 200.

The display unit 100 includes a liquid crystal display panel 110, a gray voltage generator 120, a data driver 130, a gate driver 140, a signal controller 150, and a color compensator 160.

The liquid crystal display panel 110 displays an image based on correction gray data R ″, G ″, B ″ corresponding to raw gray data R ′, G, B ′ provided from the signal controller 300. .

The liquid crystal display panel 110 includes an upper substrate (not shown), a lower substrate facing the upper substrate (not shown), and a liquid crystal layer (not shown) formed between the upper substrate and the lower substrate.

The upper substrate is formed by a thin film process to express a predetermined color using the light (RGB) (not shown), and a common electrode formed on the RGB color pixel to face the pixel electrode (not shown) It is provided.

The lower substrate includes first to nth gate lines GL1 to GLn and first to mth data lines DL1 to cross the first to nth gate lines GL1 to GLn. , ..., DLm) are formed. In this case, two data lines adjacent to two adjacent gate lines among the first to n th gate lines GL1 to GLn and the first to m th data lines DL1 to DLm are disposed. The pixel area PA is defined.

In the pixel area PA, a thin film transistor 116 and a liquid crystal capacitor connected to first to nth gate lines GL1 to GLn and first to mth data lines DL1 to DLm. 118 is formed. The liquid crystal capacitor 118 is formed by a pixel electrode (not shown) formed on the lower substrate 114, a common electrode (not shown) formed on the upper substrate 112, and the liquid crystal layer formed between the pixel electrode and the common electrode. Is formed.

The gray voltage generator 120 generates a plurality of gray voltages corresponding to an image signal input from the outside and provides them to the data driver 130. In detail, the gray voltage generator 120 generates a gray voltage corresponding to the image signal through a voltage division operation by a resistor string or a capacitor array.

The data driver 130 includes a data printed circuit board (hereinafter, referred to as a PCB, not shown) and a data driving chip (not shown). The data driver 130 receives the correction grayscale data R ″, G ″, B ″ input from the signal controller 150 into a timing system of Dot at a Time Scanning. In other words, the data driver 130 stores the correction grayscale data R ″, G ″, and B ″ input by bits from the signal controller 150 according to the shift operation. The number of bits corresponding to the two horizontal lines is stored.

In addition, the data driver 130 may be a gray voltage corresponding to the corrected gray data signals R ″, G ″, and B ″ among the plurality of gray voltages input from the gray voltage generator 120, that is, analog voltage values. The data voltages D1, ..., Dm are generated.

Subsequently, the data driver 130 transmits the generated data voltages D1,..., And Dm in response to the first timing signal T1 provided from the signal controller 150. To the m-th data line DL1, ..., DLm.

The gate driver 140 includes a gate PCB (not shown) and a gate driving chip (not shown). The gate PCB is electrically connected to the liquid crystal display panel 110 through the gate side TCP. The gate driving chip is mounted on the gate side TCP.

In addition, the gate driver 140 transfers the data voltages D1,..., Dm of the data driver 130 to the corresponding pixel area PA. Each pixel area PA of the liquid crystal display panel 110 receives the data voltages D1,..., Dm in response to an on or off operation of the thin film transistor 116.

The thin film transistor 116 is turned on or turned off by the gate driving signals G1,..., Gn provided from the gate driver 140.

The signal controller 150 may output raw grayscale data R, G, and B ′, a first timing signal T1, and a second timing signal T2 in response to the image signal VS in the form of a digital signal provided from the outside. ) The raw gray scale data R ', G, and B' are R, G, and B signals in the form of digital signals.

The first timing signal T1 is an output command signal TP and a data voltage D1, ..., Dm for instructing to apply the data voltages D1, ..., Dm to the liquid crystal display panel 110. FIG. And a line inversion signal RVS for inverting the polarity of the data voltage corresponding thereto. In addition, the first timing signal T1 further includes a horizontal clock signal HCLK for data shift in the data driver 130.

The second timing signal T2 is a gate clock signal for setting the period of the gate driving signals G1, ..., Gn applied to the first to nth gate lines GL1, ..., GLn. ), A vertical synchronization start signal STV for commanding the start of the gate driving signals G1, ..., Gn, and an output enable signal OE for enabling the output of the gate driver 140. ).

The signal controller 150 includes a first memory unit 152 therein. The first memory unit 152 stores a plurality of target color coordinate values (x ', y') input through a user or an external measuring device. In this case, the target color temperature value may be stored in the first memory unit 152 instead of the target color coordinate values (x ', y'). Thereafter, the stored target color coordinate values x 'and y' are applied to the color temperature compensator 240 and used to generate the correction signal CS from the color temperature compensator 240.

The color compensator 160 corrects the grayscale data R ', G', and B 'from the signal controller 150 based on the correction signal CS provided from the light generator 200. And the correction signal CS includes correction gamma value information, and the color compensator 160 adjusts the raw grayscale data R ', based on the correction gamma value. G ', B') are converted into correction grayscale data R ", G", B ", and output.

2 is a diagram illustrating a configuration of the color compensator 160 illustrated in FIG. 1.

Referring to FIG. 2, the color compensator 160 includes an ACC controller 162, a gamma value extractor 164, and a second memory unit 166.

The ACC controller 162 corrects the gray scale data R ″ in response to the raw gray scale data R ′, G ′ and B ′ from the signal controller 150 and the corrected gamma value γ from the gamma value extractor 164. , G ", B").

The gamma value extractor 164 receives the compensation signal CS from the color temperature compensator 240, and extracts and outputs the corrected gamma value γ from the input compensation signal CS.

The second memory unit 166 stores a plurality of gamma values including the corrected gamma value γ, and a plurality of grayscale data are stored in the form of a lookup table for each gamma value.

Referring to the operation of the color compensator 160, when the ACC controller 162 receives a correction gamma value γ corresponding to the correction signal CS from the gamma value extractor 164, the ACC controller 162 receives the correction. 2 The gradation data group corresponding to the correction gamma value γ stored in the memory unit 166 is read. At this time, the input raw gradation data R ', G', B 'is corrected to correction gradation data R ", G", B "based on the read gradation data group and output from the ACC controller 162. Hereinafter, the process of correcting the raw grayscale data with the corrected grayscale data is referred to as 'ACC correction'.

As described above, the liquid crystal display device 1000 according to the present invention may provide improved display quality by performing ACC correction to remove color shift occurring in the display device after the CCT change. Here, in the present embodiment, an example in which the signal controller 150 and the color compensator 160 are designed separately is described, but may be designed together on one chip.

The light generator 200 may include a light source 210, a light source driver 220, a light detector 230, and a color temperature compensator 240.

The light source unit 300 is disposed under the display unit 100 and generates light in response to any one of the first and second driving signals I1 and I2. In this case, the light source unit 300 includes a plurality of light emitting diodes (hereinafter, referred to as LEDs) mounted on a light source PCB (not shown).

The light detector 500 includes a light sensor (not shown) for detecting the light amount of each of the plurality of light emitting diodes, and detects the light detection signals Rd, Gd, and Bd corresponding to the detected light amount.

The color temperature compensator 240 generates and outputs a correction signal CS that corrects color temperature values of each of the plurality of LEDs in response to the light amounts Rd, Gd, and Bd detected by the light detector 230. do.

3 is a diagram illustrating a configuration of the color temperature compensator 240 illustrated in FIG. 1.

Referring to FIG. 3, the color temperature compensator 240 includes an XYZ converter 240A, a chromaticity calculator 240B, a coordinate corrector 240C, and a color temperature converter 240D.

The XYZ converter 240A receives the photodetection signals Rd, Gd and Bd and converts the input photodetection signals Rd, Gd and Bd into XYZ values of the CIE coordinate system.

The chromaticity calculator 240B calculates a raw X coordinate (x) according to a distribution of the converted XYZ value in a color temperature value corresponding to a white region of the CIE coordinate system, and based on the calculated raw X coordinate (X). The raw Y coordinate y is calculated.

The coordinate corrector 240C reads the target X coordinate x 'and the target Y coordinate y' of the CIE coordinate system corresponding to the target color temperature value stored in the first memory unit 152 of the signal controller 150, Comparing the target X coordinate (x '), the target Y coordinate (y') and the raw X coordinate (x) and the raw Y coordinate (y) input from the chromaticity calculator 240B, respectively, the comparison operation According to the result, the correction X coordinate (x ") and the correction Y coordinate (y") are output.

The color temperature converter 240D calculates a corrected color temperature value corresponding to the light detection signals Rd, Gd, and Bd based on the correction X coordinate x ″ and the correction Y coordinate y ″, A correction signal CS corresponding to the calculated corrected color temperature value is output. The correction signal CS includes a red correction signal Rc, a green correction signal Gc, and a blue correction signal Bc.

The light source driver 220 provides a driving signal for driving a plurality of LEDs of the light source unit 210. The driving signal includes a first driving signal I1 and a second driving signal I2.

The first driving signal I1 includes a first red driving signal, a first green driving signal, and a first green driving signal corresponding to the raw grayscale data R ', G', and B '. The second driving signal I2 includes a second red driving signal, a second green driving signal, and a second blue driving signal in which the first driving signal I1 is adjusted based on the correction signal CS. In this case, the driving signals are driving currents. In the present embodiment, the driving signal is a current value, but may be a voltage value.

When the light source driver 210 provides the second driving signal I2 to the light source unit 210 in response to the correction signal CS, and the correction signal CS is not applied from the color temperature compensator 240. The first driving signal I1 is maintained as it is and applied to the light source unit.

4 is a flowchart illustrating a method of driving the liquid crystal display device 1000 according to the present invention.

Referring to FIG. 4, first, the light detector 230 detects a light amount of white light corresponding to the first driving signal emitted from the light source unit 210, and converts the detected light amount into light detection signals Rd, Gd, and Bd. The output is converted (S410). Subsequently, the color temperature compensator 240 extracts the raw color coordinate values (x, y) from the output photodetection signals Rd, Gd, and Bd (S420). It is determined whether the extracted raw color coordinate values and the target color coordinate values (x ', y') provided from the first memory unit 152 of the signal controller 150 are the same (S430). In the determining step S430, when the raw color coordinate value (x, y) and the target color coordinate value (x ', y') are the same, the light source driver 220 outputs the first driving signal I1 as it is. . Therefore, the color temperature value of the white light is not corrected (S440).

On the other hand, in the determination step (S430), if the raw color coordinate value (x, y) and the target color coordinate value (x ', y') are different from each other, the color temperature compensator 240 generates a correction signal (CS) The light source driver 220 adjusts and outputs the first driving signal I1 to the second driving signal I2 based on the correction signal CS. Here, the generated correction signal CS is input to the color compensator 160 to perform 'ACC correction' (A).

FIG. 5 is a flowchart showing step A illustrated in FIG. 4 in detail.

Referring to FIG. 5, first, when the correction signal CS generated from the color temperature compensator 240 is input to the color compensator 160 (S510), the color compensator 160 may be configured from the input correction signal CS. The correction gamma value γ is extracted (S520). Subsequently, the raw gradation data R ', G', B 'input from the signal controller 150 is corrected to the correction gradation data R ", G", B "based on the extracted correction gamma value γ. (S530) The corrected grayscale data R ", G", B "is input to the data driver 130, and the data driver 130 stores the corrected grayscale data R", G ", B". The converted analog signal is input to the display panel 110, and the display panel 110 displays an image corresponding to the analog signal.

FIG. 6 is a graph illustrating a change in color temperature according to the gradation change before ACC correction after the color temperature correction of the light source unit shown in FIG. 1, and FIG. 7 is performed after the color temperature correction of the light source unit shown in FIG. It is a graph showing the change of color temperature according to the gradation change after ACC correction.

6 and 7, when the CCT value of the white light emitted from the light source unit 210 is changed, as shown in the graph of FIG. 6, the color temperature value may not be kept constant according to the gradation change. However, if the ACC correction is performed after the CCT value of the white light is changed, as shown in FIG. 7, it can be seen that the color temperature value can be kept constant according to the gradation change.

Therefore, the display device 1000 according to the present invention can not only set various CCT values, but also perform ACC correction to maintain a constant color temperature value according to gray level change after the CCT change, thereby displaying the display quality of the display device. Has the additional effect of improving the

As described above, the display device according to the present invention includes a color temperature compensator and a color compensator. The color temperature compensator changes the CCT value of the white light emitted from the light source based on the compensated color coordinate value, and outputs a correction signal including the compensated color coordinate value information to the color compensator. The color compensator performs ACC correction in response to the compensation signal.

Therefore, the present invention has the effect of standardizing the backlight and reducing the cost by changing the CCT value using the LED backlight.

In addition, the present invention may improve the display quality of the display device by performing ACC correction after minimizing the CCT value, thereby minimizing the variation of the color temperature value for each gradation according to the changed CCT value.

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.

Claims (6)

A signal controller configured to output raw grayscale data in response to a video signal provided from an external video signal source; A color compensation unit configured to receive a correction signal, extract a correction gamma value from the correction signal, and correct and output the raw gray level data as corrected gray level data based on the extracted correction gamma value; A driver which receives the correction grayscale data and outputs an analog signal corresponding to the correction grayscale data; A display panel configured to display an image corresponding to the analog signal using white light; And It includes a light generating unit for generating the white light, The light generating unit, A light detector for detecting a light amount of the white light; A light detector for outputting a light detection signal corresponding to the detected amount of light; A color temperature compensator for correcting the color temperature value of the detected light amount in response to the light detection signal and generating the correction signal based on the corrected color temperature value; A light source driver for outputting a driving signal based on the correction signal; And And a light source unit comprising a plurality of light emitting diodes generating light in response to the driving signal. The display device of claim 1, wherein each of the plurality of light emitting diodes is one of red, green, and blue light emitting diodes. The method of claim 1, wherein the color correction unit, A gamma value extraction unit for extracting a correction gamma value from the correction signal; A first memory unit which stores a plurality of grayscale values corresponding to the extracted correction gamma value; And an ACC controller that reads a plurality of grayscale values corresponding to the corrected gamma value in response to the corrected gamma value, and corrects and outputs the raw grayscale data as corrected grayscale data based on the read plurality of grayscale values. Display device characterized in that. The method of claim 1, wherein the color temperature compensator, An XYZ conversion unit receiving the light detection signal and converting the input light detection signal into an XYZ value of a CIE coordinate system; A chromaticity calculator for calculating raw coordinate values from the converted XYZ values; A coordinate beam that reads a target color coordinate value from the signal controller, calculates a difference value between the read target color coordinate value and the raw coordinate value, and corrects the raw coordinate value to a corrected coordinate value based on the difference value; government; And And a color temperature converter configured to correct a color temperature value of the light detection signal based on the corrected coordinate value, and output the corrected signal based on the corrected color temperature value. The display device of claim 4, wherein the signal controller comprises a second memory unit configured to store the target color coordinate value in the form of a lookup table. The display device of claim 1, wherein the signal controller and the color compensator are designed together on one chip.

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