KR20130036676A

KR20130036676A - Display apparatus and image quality adjustment method thereof

Info

Publication number: KR20130036676A
Application number: KR1020110100895A
Authority: KR
Inventors: 김희재; 김학량
Original assignee: 엘지전자 주식회사
Priority date: 2011-10-04
Filing date: 2011-10-04
Publication date: 2013-04-12

Abstract

PURPOSE: A display device and an image quality control method are provided to accurately control white balance, thereby preventing generation of color change in advance. CONSTITUTION: When a white color coordinate, which is expressed by a driven W pixel, corresponds to a target coordinate, a display device determines a predetermined RGB gain value and an RGB offset value as first correction data(S530). When the white color coordinate does not correspond to the target coordinate, the display device changes the predetermined RGB gain value and the RGB offset value(S540). When the first correction data is obtained, the display device expresses white as an RGB pixel in an off-state of the W pixel(S550). [Reference numerals] (S540) Find white compensation G(R'G'B)' gains & O(R'G'B') offsets;

Description

DISPLAY APPARATUS AND IMAGE QUALITY ADJUSTMENT METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a method of adjusting white balance in a 4 pixel display device.

Each of the plurality of pixels constituting the OLED display device includes an OLED pixel composed of an organic light emitting layer between an anode and a cathode, and a pixel circuit driving each OLED pixel independently. The pixel circuit mainly includes a switching transistor and a capacitor and a driving transistor. The switching transistor charges the data signal in the capacitor in response to the scan pulse, and the driving transistor adjusts the gray level of the OLED pixel by adjusting the amount of current supplied to the OLED pixel according to the magnitude of the data voltage charged in the capacitor.

Among the driving circuits driving the OLED display device, the data driver subdivides a plurality of reference gamma voltages supplied from an external gamma voltage generator into gamma voltages for each gray level, and converts digital data into analog data signals using the gamma voltages for each gray level. Convert to (current or voltage signal). The OLED display adjusts the brightness by adjusting the maximum reference gamma voltage according to the brightness adjustment signal of the user.

1 is a flowchart illustrating a step-by-step method of adjusting a white balance of a display apparatus according to the prior art. 1 is a display device for implementing colors using R pixels, G pixels, and B pixels.

Referring to FIG. 1, first, an R pixel, a G pixel, and a B pixel are driven in gray scales for representing white (step 110). That is, the R pixel is driven at 255, the G pixel at 255, and the B pixel at 255.

In this case, the gain values G (RGB) and offset (RGB offset) corresponding to the R, G, and B data are set to 0 (step 120).

Thereafter, it is determined whether the color coordinates (White x, y) represented by the sum of the R, G, and B pixels driven as described above correspond to the target value (step 130).

As a result of the determination (130), if the expressed color coordinate is not the target value, the set gain value and the offset value are changed to move the color coordinate to the target value (step 140).

Thereafter, when the expressed color coordinate corresponds to a target value according to the change of the gain value and the offset value, the finally applied gain value and the offset value are determined as correction data for white balance adjustment (step 150). That is, the gain value G (R) corresponding to the R pixel in which the color coordinate is shifted to the target value, the gain value G (G) corresponding to the G pixel, and the gain value G corresponding to the B pixel. (B)), the offset O (R) corresponding to the R pixel, the offset O (G) corresponding to the G pixel, and the offset O (B) corresponding to the B pixel for correction of white balance. Determined by the data.

However, since the above white balance adjustment method is performed by considering only R, G, and B pixels without considering W pixels, the white color coordinates represented by the W pixels and the R, G, and B pixels will be described later. There is a problem that the white balance adjustment is not performed normally due to the mismatch of the white color coordinates represented by.

According to an embodiment of the present invention, the white balance adjustment may be efficiently performed in a display device including R, G, B, and W pixels.

Technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned above are clearly understood by those skilled in the art to which the embodiments proposed from the following description belong. Could be.

According to an embodiment of the present disclosure, a method of adjusting image quality of a display apparatus may include: obtaining first correction data for moving a first white color coordinate represented by a W (white) pixel to a first target coordinate; Obtaining second correction data for moving a second white color coordinate represented by the sum of an R (red) pixel, a G (green) pixel, and a B (blue) pixel to a second target coordinate; And adjusting the white balance of the input data by using the third correction data obtained by the sum of the obtained first and second correction data.

In addition, the display device according to an embodiment of the present invention includes a display panel formed with R (red), G (green), B (blue) and W (white) pixels having an organic light emitting diode; A gate and data driver driving the gate and the data lines of the display panel, respectively; And a white balance adjusting unit for adjusting a white balance of data input from the outside and supplying the adjusted data to the data driver, wherein the white balance adjusting unit is configured to correspond to the W (white) pixel. The white balance is adjusted using first correction data and third correction data obtained based on second correction data corresponding to the R (red) pixel, the G (green) pixel, and the B (blue) pixel.

According to an exemplary embodiment of the present invention, in the display device including R, G, B, and W pixels, the color balance can be prevented in advance by accurately adjusting the white balance.

1 is a flowchart illustrating a step-by-step method of adjusting a white balance of a display apparatus according to the prior art.
2 is a diagram illustrating a configuration of a display apparatus according to an exemplary embodiment of the present invention.
FIG. 3 is a detailed configuration diagram of the display panel shown in FIG. 2.
4 is a view showing a color gamut represented by the present invention.
5 is a flowchart for explaining a method of adjusting a white balance of a display device according to an exemplary embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, except to exclude other components unless otherwise stated.

A display device according to an embodiment of the present invention is an organic light emitting display device, wherein the organic light emitting display device is excited by recombination of electrons and holes injected through an anode and a cathode into an organic material. ) And a phenomenon in which light of a specific wavelength is generated by energy of excitons formed.

The organic light emitting diode display is attracting attention as a next-generation display device because it does not require a separate light source such as a backlight, and thus has lower power consumption than a liquid crystal display, enables high image quality, and secures a wide viewing angle and fast response speed. have.

According to an embodiment of the present invention, a method of efficiently adjusting white balance in an organic light emitting display device displaying an image with R (red), G (green), B (blue), and W (white) pixels is provided. .

2 is a diagram illustrating a configuration of a display apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the display apparatus includes a display panel 210 including a plurality of pixel areas; The gate driver 230 driving the gate lines GL1 to GLn of the display panel 210, the data driver 220 driving the data lines DL1 to DLm of the display panel 210, and the display panel 210. The power supply unit 240 for applying the first and second power signals VDD and GND to the power lines PLn to PLm, and performs white balance adjustment on data input from the outside. And a white balance adjuster 250 for supplying the adjusted data to the data driver 220.

The white balance adjusting unit 250 adjusts the white balance of the data input from the outside as described above, and accordingly adjusts the white balance adjusted data according to the size and resolution of the display panel 210 so that the data driver ( 220). In addition, the white balance adjusting unit 250 generates data and gate control signals DVS and GVS to control the data and gate drivers 220 and 230.

In the display panel 210, a plurality of sub-pixels P are arranged in a matrix form in each pixel area to display an image, and each sub-pixel P is a cell driver that independently drives light-emitting cells and the light-emitting cells. (DRV). In this case, the sub-pixel P includes R, G, B, and W sub-pixels.

Specifically, referring to FIG. 3, one sub-pixel P may include a cell driver DRV and a cell driver DRV connected to one gate line GL, a data line DL, and a power supply line PL. A light emitting cell OEL is connected between the second power signal GND and equivalently represented by a diode.

The cell driver DRV is disposed between the first switching element T1, the first switching element T1, the power line PL, and the light emitting cell OEL connected to any one of the gate line GL and the data line DL. A second switching element T2 connected to the power supply line PL and a storage capacitor C connected between the power supply line PL and the first switching element T1 are provided.

The gate electrode of the first switching element T1 is connected to the gate line GL, the source electrode is connected to the data line DL, and the drain electrode is connected to the gate electrode of the second switching element T2. When the gate-on signal is supplied to the gate line GL, the first switching element T1 turns on and supplies the data signal supplied to the data line DL to the storage capacitor C and the second switching element T2. It is supplied to the gate electrode of.

The source electrode of the second switching element T2 is connected to the power supply line PL and the drain electrode is connected to the light emitting cell OEL. The second switching element T2 controls the amount of light emitted from the light emitting cell OLE by controlling the current I supplied from the power supply line PL to the light emitting cell OEL in response to a data signal from the first switching element. Will be adjusted.

The storage capacitor C is connected between the power supply line PL and the gate electrode of the second switching element T2. The second switching element T2 remains on by the voltage charged in the storage capacitor C even when the first switching element T1 is turned off, until the data signal of the next frame is supplied. The emission of (OEL) is maintained. Here, the first and second switching elements T1 and T2 may use PMOS or NMOS transistors, but the above description has been made only when NMOS transistors are used.

The gate driver 230 gates in response to a gate control signal GVS from the white balance adjuster 250, for example, a gate start pulse (GSP) and a gate shift clock (GSC). The signal is sequentially generated and the pulse width of the gate-on signal is controlled according to a gate output enable (GOE) signal. Then, the gate-on signals are sequentially supplied to the gate lines GL1 to GLn. Here, the gate-off voltage is supplied during a period in which the gate-on voltage is not supplied to the gate lines GL1 to GLn.

The data driver 220 drives input data using a source start pulse (SSP) and a source shift clock (SSC) among the data control signals DVS from the white balance controller 250. Converts to a log voltage, that is, an analog video signal. The data driver 220 supplies an image signal to each of the data lines DL1 to DLm in response to a source output enable (SOE) signal. Specifically, the data driver 220 latches data Data input according to the SSC, and then, for one horizontal line every scan period in which scan pulses are supplied to the gate lines GL1 to GLn in response to the SOE signal. Is supplied to each of the data lines DL1 to DLm.

The white balance adjusting unit 250 adjusts the white balance of the input data and outputs the data in which the white balance is adjusted. In particular, the white balance adjusting unit 250 calculates the first correction data calculated for the W pixel and the second correction data calculated for the R, G, and B pixels, and calculates the calculated first and second correction data. The final third correction data for the white balance adjustment is calculated according to the sum of.

Thereafter, the white balance adjusting unit 250 performs white balance correction of the input data using not only the calculated third correction data but also a luminance ratio between a predetermined W pixel and the R, G, and B pixels.

That is, in the display apparatus using the RGBW pixel, the weighted sum of the RGBW pixels is expressed to express white.

At this time, in order to adjust the accurate white color, it is necessary to adjust the color between the color temperature of the white represented by the W pixel and the white represented by the sum of the RGB pixels.

To this end, the white balance adjusting unit 250 allows the white color coordinates represented by the W pixels to be the same as the white color coordinates represented by the sum of the RGB pixels. At this time, if the two white color coordinates are not the same, the two coordinates are adjusted to a predetermined target coordinate.

That is, the gain value and the offset value are changed so that the white color coordinates represented by the W pixel are moved to the target coordinates, and accordingly, the first value corresponding to the gain value and the offset value used to move the white color coordinates to the target coordinates is changed. 1 Obtain the correction data. In this case, the gain value and the offset value included in the first correction data are obtained for each of R, G, and B.

Thereafter, the white balance adjusting unit 250 obtains second correction data corresponding to a gain value and an offset value for moving the white color coordinates represented by the sum of the RGB pixels to the target color coordinates. In addition, the offset value and the gain value included in the second correction data are obtained for R, G, and B, respectively.

Thereafter, the white balance adjusting unit 250 obtains third correction data calculated by the sum of the obtained first and second correction data, and performs white balance adjustment of the input data based on the third correction data. In this case, the white balance adjusting unit 250 does not perform the white balance adjustment using only the third correction data, but performs the white balance adjustment by reflecting the luminance ratio between the preset W pixel and the remaining RGB pixels.

Hereinafter, the white balance adjustment method as described above will be described in more detail.

4 is a diagram illustrating a color gamut represented by the present invention, and FIG. 5 is a flowchart illustrating a step of adjusting a white balance of a display device according to an exemplary embodiment of the present invention.

First, referring to FIG. 4, in a 4-pixel display device of RGBW, colors are divided into three areas, which are represented by conventional RGB three-primary colors, and consist of three color areas of GBW, GRW, and BRW.

At this time, in order to move the white color coordinates represented by the W pixel to the target coordinates, in order to move to the first area of FIG. 3 according to the relative position of the RGB color space, turn on the GB pixel and adjust the white to the sum, BR pixels are used to move to the second area, and GR cells are used to move to the third area.

Accordingly, first, only the W pixel is driven while the R, G, and B pixels are turned off (step 510), that is, the R, G, and B pixels are set to 0, and the W pixel is set to 255.

At this time, the initially set RGB gain value and RGB offset value is 0 (step 520).

In operation 530, it is determined whether the white color coordinates represented by the driven W pixel correspond to the target coordinates.

In operation 530, when the white color coordinate corresponds to the target coordinate, the set RGB gain value and the RGB offset value are determined as first correction data.

That is, the R gain value (G (R`)) is 0, the G gain value (G (G`)) is 0, the B gain value (G (B`)) is 0, and the R offset (O (R`)). The value is set to 0, the G offset (O (G`)) is set to 0, and the B offset value (O (B`)) is set to 0, respectively.

If the check result (step 530) and the white color coordinates do not correspond to the target coordinates, the set RGB gain value and the RGB offset value are changed (step 540). This means that the white color coordinates of the W pixels are moved to the target coordinates as a current corresponding to the luminance of R and B required to move from the coordinates of the R, G, and B pixels to the target coordinates is applied.

When the RGB gain value and the RGB offset value are changed, the process returns to step 530 to determine whether the white color coordinates represented by the changed values correspond to the target coordinates, and accordingly the changed RGB gain values. And the RGB offset value are determined as the first correction data.

When the first correction data is obtained, the white color is represented by the RGB pixel in the state where the W pixel is turned off (step 550). That is, the W pixel is set to 0, the R pixel is 255, the G pixel is 255, and the B pixel is set to 255. In addition, the RGB gain value and the RGB offset value set at this time are zero.

In operation 560, it is determined whether the white color coordinates represented by the R, G, and B pixels correspond to the target coordinates.

In operation 560, when the white color coordinate corresponds to the target coordinate, the set RGB gain value and the RGB offset value are determined as second correction data.

That is, the R gain value (G (R)) is 0, the G gain value (G (G)) is 0, the B gain value (G (B)) is 0, the R offset (O (R)) value is 0, The G offset O (G) value is set to 0 and the B offset value O (B) is set to 0, respectively.

If the check result (step 560), if the white color coordinates do not correspond to the target coordinates, the set RGB gain value and the RGB offset value is changed (step 570).

When the RGB gain value and the RGB offset value are changed, the process returns to step 560 to determine whether the white color coordinates represented by the changed values correspond to the target coordinates, and accordingly the changed RGB gain values. And the RGB offset value are determined as the second correction data.

Thereafter, when the first and second correction data are determined, the third correction data to be used for the final white balance correction is determined using the determined first and second correction data (step 580). At this time, the third correction data is obtained by the sum of the first and second correction data.

The third correction data includes an RGB gain value and an RGB offset value. In this case, the RGB gain value is determined by the sum of gain values included in the first and second correction data, and the RGB offset value is determined by the sum of offset values included in the first and second correction data.

That is, the R gain value G_Total (R) included in the third correction data is an R gain value G (R ′) included in the first correction data and an R gain value included in the second correction data ( Is the sum of G (R ')). Similarly, the G gain value G_Total (G) included in the third correction data is also the sum of the G (G) and G (G '), and the B gain value G_Total (B) is also G (B) +. It is the sum of G (B '). In addition, the R offset O_total (R) included in the third correction data is also the sum of O (R) + O (R '), and the G offset value O_total (G) is also O (G) + O ( G '), and the B offset value O_total (B) is also the sum of O (B) + O (B').

Thereafter, white balance adjustment of the input data is performed using the third correction data obtained as described above.

That is, the white balance is adjusted by multiplying the input data by a gain value included in the third correction data and adding the offset value to the input data multiplied by the gain value.

In this case, the white balance correction is performed more accurately by reflecting the luminance ratio between the W pixel and the RGB pixel.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims

Obtaining first correction data for moving a first white color coordinate represented by a W (white) pixel to a first target coordinate;
Obtaining second correction data for moving a second white color coordinate represented by the sum of an R (red) pixel, a G (green) pixel, and a B (blue) pixel to a second target coordinate; And
And adjusting the white balance of the input data by using the third correction data obtained by the sum of the obtained first and second correction data.

The method of claim 1,
And the first correction data is obtained while the R, G, and B pixels are turned off.

The method of claim 1,
And the second correction data is obtained while the W pixel is turned off.

The method of claim 1,
The first correction data includes a first gain value and a first offset value for each of R, G, and B data.
And the second correction data includes a second gain value and a second offset value for each of R, G, and B data.

5. The method of claim 4,
And the third correction data includes a third gain value obtained by the sum of the first and second gain values of the same data and a third offset value obtained by the sum of the first and second offset values.

6. The method of claim 5,
Performing the white balance correction,
And outputting data obtained by adding the third offset value to a product of respective input data input from an external device and the third gain value.

The method according to claim 6,
And the output data is changed by a luminance ratio between the R, G, and B pixels and the W pixel.

The method of claim 1,
And the first target coordinates and the second target coordinates are the same.

A display panel including R (red), G (green), B (blue), and W (white) pixels having an organic light emitting diode;
A gate and data driver driving the gate and the data lines of the display panel, respectively; And
A white balance adjusting unit for adjusting a white balance of data input from the outside and supplying the adjusted data to the data driver;
The white balance adjustment unit,
Using third correction data acquired based on first correction data corresponding to the W (white) pixel and second correction data corresponding to the R (red) pixel, G (green) pixel, and B (blue) pixel And adjusting the white balance.

The method of claim 9,
And the first correction data includes a gain value and an offset value for each input data for moving a white color coordinate represented by the W pixel to a target coordinate while the R, G, and B pixels are turned off.

The method of claim 9,
The second correction data includes a display device including a gain value and an offset value for each input data for moving a white color coordinate represented by the sum of the R, G, and B pixels to a target color coordinate while the W pixel is turned off. .

The method of claim 9,
And the third correction data is a sum of the first correction data and the second correction data.

5. The method of claim 4,
And the white balance correction unit adjusts the white balance by reflecting a luminance ratio between predetermined R, G, and B pixels and the W pixel.