KR102558945B1 - Display with inversion and method controlling thereof - Google Patents

Abstract

The present invention relates to a display device to which a polarity change is applied and a method for controlling the same. The display device according to one embodiment of the present invention compensates for and outputs a data signal to be applied to a subpixel whose polarity is changed in dot inversion. A method for controlling a display device according to another embodiment of the present invention includes a method of differently compensating and outputting a subpixel whose polarity is changed and a subpixel whose polarity is not changed when a timing controller or a signal controller applies a data signal and a gate signal to a display device.

Description

Display device with polarity change and method for controlling it {DISPLAY WITH INVERSION AND METHOD CONTROLLING THEREOF}

The present invention is a patent for a display device to which polarity change is applied and a method for controlling the display device.

A display device is a device that visually displays data, such as a liquid crystal display, an electrophoretic display, an organic light emitting display, an inorganic EL display, an electro luminescent display, a field emission display, a surface-conduction electron-emitter display, a plasma display, and a cathode ray tube display. , Display), etc.

Among them, in particular, liquid crystal displays (LCDs) are in the limelight recently due to advantages such as mass production technology, ease of driving means, realization of high image quality, and realization of large-area screens.

A liquid crystal display device (LCD) is an electronic device that converts various electrical information generated from various devices into visual information by using a change in liquid crystal transmittance according to an applied voltage and transmits it. A liquid crystal display device is widely used as an alternative means capable of overcoming the disadvantages of a conventional CRT (Cathode Ray Tube) because it can implement low-power driving, a thin structure, and excellent image quality.

Such a liquid crystal display device can be largely divided into a display unit, a circuit unit, and a backlight unit. The display unit is responsible for displaying an image by adjusting the amount of transmitted light, and the circuit unit functions to apply various signals transmitted from the drive system to the display unit and control these signals, and the backlight unit is used as a light control device that radiates light evenly throughout the display unit.

Specifically, the display unit is made of liquid crystal interposed between two substrates facing each other, and an image is displayed by changing the arrangement of liquid crystals by an electric field generated with the liquid crystal interposed therebetween. A polarizing plate is attached to the outside of the two substrates, respectively.

The circuit unit includes various circuit elements and a printed circuit board (PCB) to control the overall driving of the liquid crystal display device.

A backlight unit (BLU) is a light source of a liquid crystal display device, and is a light supplying device provided because the liquid crystal display device does not emit light itself and is a light receiving element that displays an image by adjusting the transmittance of light coming from the outside.

That is, the liquid crystal display device includes a liquid crystal panel in which a plurality of pixels are arranged in a matrix form, a driving circuit for driving the liquid crystal panel, and a backlight unit for irradiating light to the liquid crystal panel.

As described above, the liquid crystal display device can implement an image by adjusting the light transmittance of the liquid crystal cell according to the gray level value of the data signal. That is, a fixation phenomenon of the liquid crystal cell due to direct current occurs, which causes an afterimage on an image displayed on the liquid crystal panel.

Inversion is applied to the liquid crystal cells to prevent fixation of the liquid crystal cells due to direct current. Inversion is to change or invert the data signal supplied to the liquid crystal cells based on the common voltage (Vcom), and frame inversion, line inversion, column inversion, dot inversion, etc. are used according to the unit of inversion.

On the other hand, it is possible to compensate for the data signal applied to the liquid crystal cell, which means that the data signal is partially increased or decreased in order to properly express the color that the corresponding liquid crystal cell originally wants to express.

When the polarity of the liquid crystal cell changes according to the inversion, it must be implemented in a different way from the compensation of the data signal when the voltage of the same polarity is applied, and in particular, when the polarity is different between the lines to which the data signal is applied.

The present invention proposes a method for enabling a data signal to accurately implement an image in dot inversion.

The present invention proposes a method for fast charging even when the polarity of a data signal is reversed in dot inversion.

The present invention proposes a technology for driving a liquid crystal display device by implementing charging in a different manner when the polarity is reversed and when the polarity is not reversed in dot inversion.

A display device according to an embodiment of the present invention includes a display device that compensates for and outputs a data signal to be applied to a sub-pixel whose polarity is changed in dot inversion.

A display device according to another embodiment of the present invention includes a display device that calculates and outputs a compensation value independent of a data signal of a previous line when compensating a data signal to be applied to a subpixel whose polarity is changed in dot inversion.

A display device according to another embodiment of the present invention includes a display device that calculates and outputs a compensation value by setting a data signal of a previous line to be 0 grain when compensating for a data signal to be applied to a subpixel whose polarity is changed in dot inversion.

A method of controlling a display device according to another embodiment of the present invention includes a method of differently compensating and outputting subpixels whose polarities are changed and subpixels whose polarities are not changed when a timing controller or a signal controller applies a data signal and a gate signal to the display device.

A method of controlling a display device according to another embodiment of the present invention includes a method of compensating for a subpixel whose polarity does not change by using a first gray value of a data signal applied to subpixels to subpixels connected to the same data line and a previous gate line, and compensating and outputting data signals of subpixels whose polarity is changed by using a second gray value different from the first gray value, when a timing controller or a signal controller applies a data signal and a gate signal to the display device.

When the present invention is applied, a display device and method for compensating a data signal to accurately implement an image in dot inversion are provided.

When the present invention is applied, a display device and method for rapidly performing charging even when the polarity of a data signal is reversed in dot inversion are provided.

When the present invention is applied, in compensating for a data signal to be applied to a sub-pixel whose polarity is changed in dot inversion, a compensation value independent of a data signal of a previous line is calculated and output to provide a display device in which weak charging is compensated.

1 is a view showing a liquid crystal display device to which an embodiment of the present invention is applied.
2 is a diagram showing an N-dot inversion to which the present invention can be applied.
FIG. 3 is a diagram showing the size of the data signal 300 for each color and pixel indicated by 211 in FIG. 2 .
4 is a diagram showing the configuration of the timing controller 140 according to an embodiment of the present invention.
5 is a diagram showing a data signal compensation process according to an embodiment of the present invention.
6 is a diagram showing the configuration of a first lookup table according to an embodiment of the present invention.
7 is a diagram showing the configuration of a second lookup table according to an embodiment of the present invention.
8 is a diagram showing a data signal compensation process according to another embodiment of the present invention.
FIG. 9 is a diagram showing a waveform compensated for by overdriving and solving weak charging when a previous gate line is set to 0 gray upon polarity inversion according to an embodiment of the present invention.
10 is a diagram showing a lookup table according to an embodiment of the present invention.
11 is a diagram illustrating a process of applying a data signal, that is, a data voltage value, when line overdriving according to an embodiment of the present invention is applied.
12 is a diagram showing an example of a lookup table applied when polarity is changed according to an embodiment of the present invention.
13 is a diagram illustrating a process of applying different compensation values according to whether a polarity is inverted by a timing controller according to an embodiment of the present invention.
14 is a diagram showing the configuration of each component in another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings so that those skilled in the art can easily carry out the present invention. This invention may be embodied in many different forms and is not limited to the embodiments set forth herein.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification. In addition, some embodiments of the present invention are described in detail with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted.

Hereinafter, providing or disposing an arbitrary element on the "upper (or lower)" or "upper (or lower)" of a substrate means that the arbitrary element is provided or disposed in contact with the upper surface (or lower surface) of the substrate, and is not limited to not including other elements between the substrate and any element provided or disposed on (or under) the substrate. Also, terms such as first, second, A, B, (a), and (b) may be used in describing the components of the present invention. These terms are only used to distinguish the component from other components, and the nature, sequence, order, or number of the corresponding component is not limited by the term. It should be understood that when an element is described as being “connected”, “coupled” or “connected” to another element, the element may be directly connected or connected to the other element, but other elements may be “interposed” between the elements, or each element may be “connected”, “coupled” or “connected” through other elements.

1 is a view showing a liquid crystal display device to which an embodiment of the present invention is applied. The display device 100 to which the embodiments are applied includes a display panel 110 in which gate lines GL1 to GLn and data lines DL1 to DLm intersect, a gate driver 120 for driving the gate lines disposed on the display panel 110, a data driver 130 for driving the data lines disposed on the display panel 110, and timing controlling driving timings of the gate driver 120 and the data driver 130. A controller (Timing Controller, 140) and the like are included.

Each sub-pixel P is defined in the display panel 110 by crossing the gate lines GL1 to GLn and the data lines DL1 to DLm. The sub-pixel is for displaying one color and can display any one color among red (R), green (G), blue (B), and selectively white (W). The aforementioned colors may be replaced according to embodiments.

The gate driver 120 drives the gate lines GL1 to GLn by sequentially supplying scan signals to the gate lines GL1 to GLn. To this end, it receives a clock signal and sequentially supplies scan signals to the gate lines GL1 to GLn based on the received clock signal.

The timing controller 140 may be configured on a source printed circuit board (PCB), and a gate drive integrated circuit (hereinafter referred to as a 'gate drive IC') may be connected to a display panel in a Tape Automated Bonding (TAB) method, configured on a display panel in a COG (Chip On Glass) method, or electrically connected to a display panel in a COF (Chip On Film) method.

The timing controller 140 receives image data (RGB), a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), a dot clock signal (DCLK), a data enable signal (DE), etc. from the outside, applies a gate control signal (GCS) to the gate driver 120, and applies the data control signal (DCS) and image data (R'G'B') to the data driver 130 for displaying the above-described image data (RGB) by sub-pixels. . The data driver 130 may also be divided into a plurality of integrated circuits. For example, source drive ICs are controlled to apply signals to data lines within a predetermined area.

Hereinafter, a display device for compensating and outputting a data signal to be applied to a sub-pixel whose polarity is changed in dot inversion according to an embodiment of the present invention will be described. In addition, the present display device includes a display device that calculates and outputs a compensation value independent of a data signal of a previous line when compensating for a data signal to be applied to a subpixel whose polarity is changed in dot inversion.

A display device according to another embodiment of the present invention includes a display device for calculating and outputting a compensation value by setting the data signal of the previous line to 0 grain in compensating for a data signal to be applied to a sub-pixel whose polarity is changed in dot inversion.

2 is a diagram showing an N-dot inversion to which the present invention can be applied. N-dot inversion is a technique of applying the same polarity to a plurality of dots (sub-pixels) and then applying opposite polarities to N dots (sub-pixels). 2 shows a pixel structure of 4-dot inversion. In FIG. 2 , R, G, B, and W are indicated as colors of each sub-pixel connected to the gate line GL and data line DL, and the polarity of data applied to each sub-pixel in the frame is indicated by + and -. Two sub-pixels are connected to one data line, and looking at the order in which the liquid crystal cells of the sub-pixels operate, in DL(i), G(-), R(-), W(-), B(+), G(+), R(+), W(+), B(-). Here, pixels whose polarity is reversed in the same data line are B (201, 202). Similarly, in DL (i+1) and DL (i+2), all pixels whose polarity is reversed in the order 211, 212 in which liquid crystal cells of sub-pixels operate are B (203, 204, 205, 206).

FIG. 3 is a diagram showing the size of the data signal 300 for each color and pixel indicated by 211 in FIG. 2 . A + polarity is applied from the blue sub-pixel indicated at 203 of 211, and a - polarity is applied from the blue sub-pixel indicated at 204. The data signal 300 means the magnitude of the voltage applied to the data line, but the present invention is not necessarily limited thereto, and all data signals for expressing RGB are included in the embodiment of the present invention.

When driving N-dot inversion, a polarity change occurs within a frame. At the time of polarity change, weak charging occurs due to data line delay. If the polarity is changed to another gray color, the line OD (Line Over driving, or PCID) operates to compensate for the weak charging. However, if the same gray color is maintained as in the example of FIG.

Therefore, in the embodiment of the present invention, a method for applying an accurate compensation value even when the polarity is changed in implementing dot inversion will be examined. To this end, in one embodiment of the present invention, the data value of the previous line referred to for compensation at the time when the polarity is maintained and the data value of the previous line referred for compensation at the time when the polarity is reversed can be set to be different.

4 is a diagram showing the configuration of the timing controller 140 according to an embodiment of the present invention.

The timing controller 140 includes an inversion signal unit 1410, a data output unit 1420, and a memory 1430.

The inverting signal unit 1410 provides a signal indicating the polarity of a data signal to be applied to the data line to the data driver in order to implement dot inversion. The inversion signal unit 1410 applies a polarity inversion signal to the data driver according to an inversion implemented or when a frame is switched. In addition, the data output unit 1420 calculates a first compensation value (prev_RGB_comp1) or a second compensation value (prev_RGB_comp2) using a data signal applied to a sub-pixel of a previous data line in response to whether or not the polarity of the data signal applied to the corresponding data line is inverted according to an embodiment of the present invention, and outputs R'G'B' obtained by compensating the RGB value to be displayed in the corresponding data line. The output R'G'B' is applied to a data driver and applied to each of a plurality of sub-pixels defined by a plurality of data lines connected to one gate line.

In summary, the inversion signal unit 1410 instructs inversion of the polarity of the data signal of the first subpixel connected to the first data line and connected to the first gate line and the polarity of the data signal of the second subpixel connected to the first data line and connected to the second gate line.

The data output unit 1420 calculates a first compensation value or a second compensation value from the data signal applied to the first sub-pixel in response to the signal of the inverted signal unit, and compensates and outputs the data signal of the second sub-pixel. In this process, a lookup table stored in the memory 1430 may be used, and the lookup table may store RGB values of previous data lines and compensation values corresponding thereto. In order to vary the compensation value according to polarity inversion, the timing controller 140 may include a plurality of lookup tables, may include lookup tables (LUTs) having different memory sizes, or may include one lookup table and a calculation module. In addition, in this specification, the inversion signal unit 1410, the data output unit 1420, and the memory 1430 may be configured as separate modules outside the timing controller. It may be configured in various ways, and the present invention is not limited thereto.

As in the embodiment of FIG. 4 , in the first sub-pixel and the second sub-pixel connected to the same gate line, when the polarities of the two sub-pixels are changed in the process of outputting an image from the second sub-pixel immediately after the image is output from the first sub-pixel, a compensation value for compensating for weak charging is set to be different from a compensation value in the case of no polarity change so that accurate compensation can be made in the second sub-pixel even if the polarity change occurs. In particular, when the polarity is changed through this and there is no difference in gray before and after the polarity change, the weak charging problem is serious, but when the present invention is applied, the weak charging problem can be solved.

Hereinafter, an embodiment of compensation according to the configuration of the data output unit 1420 and the memory 1430 according to an embodiment of the present invention will be described.

5 is a diagram showing a data signal compensation process according to an embodiment of the present invention. In the embodiment of FIG. 5, whether the polarity is changed, that is, whether the polarity is reversed, is recognized, and when the polarity is maintained, the data of the first lookup table applied to compensation is used, and when the polarity is changed, the second lookup table in which the value of the data signal of the previous line entering the lookup table is fixed to 0 gray is used. 5 shows a process in which the data output unit 1420 compensates for a data signal when a polarity inversion occurs using a memory. That is, two types of look-up tables are used, but the second look-up table used when the polarity is changed has a reduced memory storage space compared to the first look-up table.

In one embodiment, the second lookup table fixes the data signal applied to the previous line to 0 gray to minimize the additional memory space, and is manufactured and applied with a corrected value in consideration of the slightly charged value at the moment when the polarity is changed.

In more detail, it includes a first lookup table 1430a optimized for displaying a 2D image or a 3D image and a second lookup table 1430b applicable when the polarity is changed. Cur.line means the gate line where the current data is to be output, and Prev.line means the gate line where data is output before Cur.line. Xc (Cur.line) means the RGB value to be output from Cur.line, and Xc' (Cur.line) means the RGB value after applying compensation. Xp(Prev.line) means the RGB value output from Prev.line.

In S501, it is checked whether the polarity is reversed in the sub-pixel connected to Cur.line. This may use the information of the inversion signal unit 1410 of FIG. 4 described above. When the polarity is not reversed and is the same, the first compensation value to be compensated is calculated in the first lookup table 1430a using the RGB value (Xp(Prev.line)) of the previous line (Prev.line) stored in the line memory 1439, and the calculated Xc' (Cur.line) is applied to the data driver.

According to an embodiment of the present invention, data values stored in the line memory 1439 may be RGB values of the previous line or values obtained by compensating RGB values.

Meanwhile, when the polarity is reversed, the RGB value (Xp(Prev.line)) of the previous line (Prev.line) stored in the line memory 1439 is set to 0 gray, and the second compensation value to be compensated is calculated in the second lookup table 1430b. The calculated Xc' (Cur.line) is applied to the data driver.

When the polarity is reversed, the size of the second look-up table storing the value of the data signal applied to the previous data line to be referenced for compensation may be smaller than the size of the first look-up table. For example, the second lookup table may be configured to correspond to a 0 gray value even if the RGB values of the previous line are varied.

6 is a diagram showing the configuration of a first lookup table according to an embodiment of the present invention. In an embodiment consisting of a total of 16 steps when indexing data signals that can be expressed, if the RGB gradation values (size of the data signal or gray value) corresponding to each step (idx_0 to idx_15) are G0 to G15, the lookup table has the same configuration as 1430a. More specifically, the range of the data signal applied from the previous gate line is G0 to G15 as suggested in Xp (Prev.line), and the corresponding index is idx_0 to idx_15. 1431a. As suggested in Xc (Cur.line), the range of the data signal to be applied from the current gate line is G0 to G15, and the corresponding index is idx_0 to idx_15. 1432a.

As a result, when the data signal applied from the previous gate line is G2 and the data signal to be applied from the current gate line is G14, the result of applying the first compensation value is G'(14, 2). For example, if the data signal to be applied to the current gate line corresponds to G14 and G14 is 890 and the data signal applied to the previous gate line corresponds to G2 and is 128, G'(14, 2) may be 980.

When the gradation of each pixel in all gradation levels is k, the size of the first lookup table of FIG. 6 may be the square of k (k ² ).

7 is a diagram showing the configuration of a second lookup table according to an embodiment of the present invention. When the polarity is reversed, G0 is set as the data signal of the previous line independently of the data signal of the previous line (1433b). Accordingly, when the data signal to be applied from the current gate line is G1 and the data signal applied from the previous gate line is G2, the result of applying the second compensation value is G'(2, 0). And even when the data signal applied from the previous gate line is G5, it is G'(2, 0). Looking at the configuration of the second lookup table 1430b, when the gray level of each pixel in every gray level step is k, the size of the second lookup table in FIG. 7 is k, and compared to the first lookup table in FIG. When the polarity is changed, a second lookup table having a smaller number of columns than the first lookup table may be provided for the previous line in order to solve the weak charging problem due to the size of the data signal of the previous polarity and at the same time to reduce the memory capacity for the polarity change. FIG. 7 may be an embodiment of a memory referred to in logic for performing polarity compensation by the polarity compensator 1425 in the structure of FIG. 8 to be described later.

One embodiment of the second lookup table is a case of having one column for setting the gray level of the data signal of the previous line to 0 or a specific value. In another embodiment, the gray level of the data signal of the previous line is limited to a specific gray level (for example, 0, 1, 2, etc.) to lower the memory capacity.

Meanwhile, in FIG. 7 , when there is a polarity inversion, the data signal is set to 0 gray in the second lookup table. This is to apply the charge share operation to solve the problem of weak charging when there is polarity inversion.

Referring to FIGS. 6 and 7 , a lookup table suitable for polarity change can be provided without a separate lookup table equal to the size occupied by the lookup table when the polarity is not changed, and as a result, the size of memory to be implemented in the display device can be reduced.

8 is a diagram showing a data signal compensation process according to another embodiment of the present invention. Unlike FIGS. 5 to 7 , the data output unit 1420 calculates and outputs a compensation value of a data signal to be output to a polarity inverted pixel using a separate compensation module without referring to a separate memory at the time of polarity inversion.

In more detail, it includes a first lookup table 1430a optimized for displaying a 2D image or a 3D image, and a compensation unit 1425 that can be applied when the polarity is changed. Cur.line means the gate line where the current data is to be output, and Prev.line means the gate line where data is output before Cur.line. Xc (Cur.line) means the RGB value to be output from Cur.line, and Xc' (Cur.line) means the RGB value after applying compensation. Xp(Prev.line) means the RGB value output from Prev.line.

In S801, it is checked whether the polarity is reversed in the sub-pixel connected to Cur.line. This may use the information of the inversion signal unit 1410 of FIG. 4 described above. When the polarity is not reversed and is the same, the first compensation value to be compensated is calculated in the first lookup table 1430a using the RGB value (Xp(Prev.line)) of the previous line (Prev.line) stored in the line memory 1439, and the calculated Xc' (Cur.line) is applied to the data driver.

On the other hand, when the polarity is reversed, the polarity compensation unit 1425 sets the RGB value (Xp(Prev.line)) of the previous line (Prev.line) to 0 gray to calculate the second compensation value, and the calculated Xc' (Cur.line) is applied to the data driver.

For compensation when the polarity is reversed, the polarity compensation unit 1425 is a module that calculates a compensation value corresponding to a 0 gray value without using the value of the data signal applied to the previous data line. That is, the polarity compensator 1425 may calculate a second compensation value obtained by compensating the data signal applied to the first sub-pixel and the data signal of the independent second sub-pixel. As for the second compensation value that compensates for the data signal of the independent second sub-pixel, the gray value of the previous line is set to 0 as shown in FIG. Because the polarity is changed, the difference in gray value from the previous line does not yield an effective compensation result. In this specification, a specific gray value can be set independently from the previous line to compensate for weak charging.

As described above, the specific gray value may be a 0 gray value. When set to 0 gray value, since the largest gray difference occurs regardless of the value of the data signal of the current line, a second compensation value higher than the original data signal can be output to the display device through the gray difference.

8 applies line overdriving by setting the data signal of the previous line to be fixed to a specific value, for example, 0, when the polarity is changed or the polarity is reversed without adding a separate lookup table. Compensation is possible when the same gray color is maintained at the time of polarity change, and even when the gray color is changed, a larger value than the existing overdriving can be applied to compensate for weak charging. Since compensation at the time of polarity change also uses the value of the existing lookup table as it is, a process of resetting the line overdriving LUT value to a level that does not cause image defects can be additionally added in consideration of this. The polarity compensator 1425 does not use a separate memory and sets the data of the previous line to a specific gray color depending on whether the polarity is changed, so memory capacity can be reduced. In addition, the polarity compensator 1425 may apply a separate compensation logic to collectively set a specific gray value, such as 0 gray, in various ways for the data of the previous line. Depending on the range of the gray value of the previous data line, whether to set it to 0 gray value or 1 gray value can be determined.

The polarity compensation unit 1425 of FIG. 8 may separately include a memory as shown in FIG. 7 to calculate a compensation value.

FIG. 9 is a diagram showing a waveform compensated for by overdriving and solving weak charging when a previous gate line is set to 0 gray upon polarity inversion according to an embodiment of the present invention. When the polarity is reversed while maintaining the same gray in FIG. 9, for example, when maintaining 127 in the same gray as in 910 and switching from negative (-) polarity to positive (+) polarity, a 0 gray step 810 is added to apply the charge share effect so that 127 grays of positive polarity can be output. Likewise, even when the polarity of 127, which is the same gray as 920, is maintained and the polarity is reversed from positive to negative, a charge share effect can be applied by adding a 0 gray step 820 so that 127 gray of negative polarity can be output. This increases the absolute value difference between the grays, thereby preventing weak charging from occurring in the inverted polarity.

That is, when the data of the previous line is fixed to 0 gray instead of actually output gray according to the configuration of the second lookup table of FIG. 7 , overdriving is compensated so that data values suitable for polarity change can be output.

Similarly, in a structure in which the polarity compensator 1425 of FIG. 8 converts the gray color of the previous line to 0 and outputs a corresponding compensation value, data values may be output appropriately to the polarity change by being compensated by overdriving.

Hereinafter, FIGS. 10 to 13 are diagrams showing a compensation process to which an embodiment of the present invention is applied. 6, a process of compensating a gray value to be applied to a sub-pixel of a current gate line by using a gray value applied to a sub-pixel of a previous gate line has been described. For convenience of description, the look-up table of FIG. 6 is simplified and described focusing on the case of a total of 8 gray indices.

10 is a diagram showing a lookup table according to an embodiment of the present invention. Eight gray indices are set.

11 is a diagram illustrating a process of applying a data signal, that is, a data voltage value, when line overdriving according to an embodiment of the present invention is applied.

1110 is a configuration in which voltage is applied without compensation. The digital waveform is the same as 1111, and the change of the data voltage of the data line for this is 1112. On the other hand, when compensation is applied, it is the same as 1120, the digital waveform is the same as 1121, and the change of the data voltage of the data line for this is the same as 1122. Here, 1122 rises to a certain level at point 1122a and then goes down again. This is when compensation is applied, and a voltage higher than the data voltage to be output is applied to the actual data line, which is to prevent weak charging.

When compensation is not applied and when compensation is applied, as in 1110 and 1120, the size of the data voltage applied to the pixel is the same as in 1130. PCID driving such as 1120, that is, line overriding, utilizes line memory to compare lines and apply overdriving (OD). As an example, in the case of the G+ structure, data is output in the order of BGRW. When outputting the data of G, for example, the previous data value is compared with the data value of B. As the resolution increases, the shortfall in charging time is solved by overdriving the data value, which applies an appropriate level differently from the value that applies OD for each frame. The data output value graph of 1130 is to show an example of PCID application, and it shows random output. The same gray value as the previous data is output as it is, and when the gray color is changed, a value to which OD is applied according to the LUT is applied as shown in FIG. Therefore, as in the lookup table examined in FIG. 10, when gray is 0 or a low value close to 0, a larger value is compensated, so in the present invention, the lookup table is additionally used at the time when the polarity is changed. The compensation value can be calculated by setting the gray of the previous data to 0 or a value close to it. Alternatively, the polarity compensation unit sets the gray color of the previous data to 0 or a value close thereto and controls the output of the compensated data signal.

12 is a diagram showing an example of a lookup table applied when polarity is changed according to an embodiment of the present invention.

1210 is a case where a value applied when the gray value is 0 in FIG. 10 is imported as it is. 1220 is a case in which a separate value to be applied when the polarity is changed is included, different from a value applied when the gray value is 0 in FIG. 10 . In the case of 1210, the timing controller separately has a lookup table such as 1210, and when the polarity is changed, a compensation value may be calculated by setting a gray value of a previous line to 0. In addition, without a separate lookup table, the lookup table of FIG. 10 is used, but if the polarity is changed, the gray value of the previous line of the line memory is restored to 0, and then the compensation value can be calculated.

Meanwhile, the 1220 has a separate lookup memory, and can maintain a more optimized lookup table to compensate for weak charging corresponding to a change in polarity.

When overdriving is applied for each frame, the polarity of all sub-pixels is compared with a constantly changing value, so there is no need to separately consider the polarity. On the other hand, in the case of PCID, in the process of comparing data line by line, there is a situation in which subpixels with the same polarity and subpixels that do not change are connected to the same gate line and occur simultaneously. In this case, when the same lookup table (LUT) is used for subpixels in different situations, weak charging of subpixels with changed polarity occurs. In the case of weak charging by applying the present invention described above, a separate lookup table is used, or a mechanism to compensate for polarity change (set the data of the previous line to be compared to a constant value method) can be separately provided to solve the problem of weak charging. As an embodiment, when the gray of the data signal of the previous line is set to a low gray such as 0 gray, even if the polarity is reversed, the charging time can be reduced through the same effect as the charge share as shown in FIGS. 9 and 11 . That is, when set to 0 gray, the gray value of the compensated data signal is greater than the gray value of the original RGB, and accordingly, the problem of relatively weak charging can be solved.

As shown in FIG. 10, the lookup table based on the same polarity is compared by setting eight grays as reference points. It is configured as a gray value by comparing the value of the previous data with the current data and dividing the input (Over Driving) value that is larger than the desired output value by 8 x 8. The output of 0 gray and 63 gray has no effect because the value to which OD is applied cannot be output. As shown in FIG. 12, the LUT to which the polarity change criterion of FIG. 5 is applied is applied while the previous data (Xp(Prev.line)) is fixed to 0 gray, so necessary data is reduced. Since it is applied only when the polarity is changed, a LUT with a larger OD value is required because charging is less than in the case where 0 gray is the previous data in the same polarity. In FIG. 8, the same polarity reference LUT is used instead of using individual LUTs in the polarity change reference, and PCID is applied while the previous data is fixed to 0 gray instead. Although the data entering the LUT can be reduced, appropriate data can be applied because the compensation value by changing the polarity and the compensation value in case of the same polarity are applied equally.

Hereinafter, a method for controlling a display device according to another embodiment of the present invention will be described. This includes a method of differently compensating and outputting subpixels whose polarity is changed and subpixels whose polarity is not changed when the timing controller or signal controller applies the data signal and the gate signal to the display device. In addition, a method of controlling a display device according to another embodiment of the present invention includes a method in which a timing controller or a signal controller applies a data signal and a gate signal to a display device, and compensates for a subpixel whose polarity is not changed by using a first gray value of a data signal applied to subpixels connected to the same data line and a previous gate line, and compensates and outputs data signals of subpixels whose polarity is changed by using a second gray value different from the first gray value.

13 is a diagram illustrating a process of applying different compensation values according to whether a polarity is inverted by a timing controller according to an embodiment of the present invention. It shows the process of controlling the polarity change of the timing controller in the display panel in which the gate lines and the data lines are crossed. 13 also corresponds to the operation of not only the timing controller but also a separate module for applying a data signal to the display panel in combination with the timing controller.

The timing controller sequentially applies gate signals to gate lines and applies data signals to data lines so that subpixels corresponding thereto can express RGB(W). In this process, the timing controller applies a gate signal to the first gate line and outputs data signals to each of the plurality of data lines (S1310). This data signal may be a data signal to which the aforementioned compensation value is applied. The timing controller stores the value of the data signal of the sub-pixel connected to the first gate line in the line memory (S1320). As described above, data signals output from sub-pixels may be stored in the line memory, and data signals corresponding to RGB before compensation may be stored in the line memory. Then, the value of the data signal of the sub-pixel connected to the second gate line is checked (S1330). Then, the polarity change is confirmed for each sub-pixel (S1335).

That is, the timing controller compares the polarities of the subpixels connected to the first gate line to which the gate signal was applied immediately before with the polarities of the subpixels connected to the second gate line to which the gate signal is to be applied (S1340). As reviewed in FIG. 2 , among subpixels connected to the same gate line, there are subpixels whose polarity is changed and other subpixels. Among the pixels connected to GLj+3) in FIG. 2 , it was confirmed that only B (201) and B (205) had their polarities changed, and that the polarities of the other sub-pixels were not changed. The timing controller determines an output data value of the corresponding sub-pixel by applying a first gray value of the data signal of the first gate line to the existing look-up table for data signals of sub-pixels connected to the same data line and having no polarity change (S1350).

In other words, the timing controller compensates data signals of subpixels connected to the same data line and whose polarity is not changed using the first gray value of the data signal applied to the first gate line and the subpixels connected to the same data line. For example, in FIG. 2, the first gate line is GL(j+2), the second gate line is GL(j+3), and R(212), which is a sub-pixel connected to the second gate line and the data line (i+1), has no polarity change compared to G(211). Accordingly, compensation is performed using the gray value (first gray value) of the data signal applied to G(211) connected to the first gate line GL(j+2) and the data line (i+1).

Meanwhile, the timing controller is connected to the same data line and determines an output data value of the corresponding sub-pixel by using a second gray value for data signals of sub-pixels whose polarity is changed (S1360). As described above, the second gray value includes an embodiment in which the data signal of the first gate line is set to be 0 gray and compensated using a look-up table, or the polarity compensator sets the value of the line memory to 0 gray and extracts a value to be compensated from the look-up table.

In other words, the timing controller is connected to the same data line and compensates data signals of subpixels whose polarity is changed using the second gray value.

For example, in FIG. 2, the first gate line is GL(j+2), the second gate line is GL(j+3), and the polarity of B (201), which is a sub-pixel connected to the second gate line and data line (i), is changed compared to W (213). Therefore, instead of the data signal applied to W 213 connected to the first gate line GL(j+2) and the data line (i), the gray value is set to a separate second gray value such as 0, and the data signal to be output from B 201 can be compensated using the lookup table as shown in FIG. 7 or FIG. 12. In addition, as shown in FIG. 8 , the data signal to be output from B 201 can be compensated by setting the gray value to a separate second gray value such as 0 and using the lookup table shown in FIG. 6 or FIG. 10 .

As another embodiment, in the process of compensating using the second gray value, if the data signals of the sub-pixels whose polarity is changed are smaller than the preset gray value, the second gray value is applied to compensate, and if the data signals of the sub-pixels whose polarity is changed are greater than the preset gray value, the third gray value can be applied to compensate. That is, the second gray value or the third gray value may be applied according to the size of the gray value of the data signal of the subpixel whose polarity is changed. As an embodiment, referring to FIG. 7 above, when the gray values of the data signal of the sub-pixel whose polarity is changed are G0 to G7, the second gray value is applied, and when the gray value of the data signal of the sub-pixel whose polarity is changed is G8 to G15, the third gray value can be applied. This includes that even in the case of a sub-pixel whose polarity is changed, a compensated size may be differently applied according to the gray level. As a result, various levels of compensation can be applied to sub-pixels whose polarity is changed.

In particular, the third gray value may be set lower than the second gray value. This is to differentiate the difference according to the gray value. In one embodiment, when the gray value of the data signal of the subpixel is G0 to G7, 1 is applied as the second gray value used for compensation, and when the gray value of the data signal of the subpixel whose polarity is changed is G8 to G15, 0 can be applied as the third gray value used for compensation.

The timing controller outputs data signals of subpixels to which line overdriving is applied, that is, to which a compensation mechanism is applied, to a source driver integrated circuit that controls the corresponding data line, and applies a gate signal to a second gate line so that the subpixels can output RGB(W). Through the process shown in FIG. 13, the compensation value of the subpixel whose polarity is not changed is different from the compensation value of the subpixel whose polarity is changed. Even if the polarity is changed, the subpixel whose polarity is changed can be charged through overcharging through overdriving.

14 is a diagram showing the configuration of each component in another embodiment of the present invention. A plurality of gate driver ICs 121a and 121b constituting the gate driver 120 for controlling signals to display an image on the display panel 110, and a plurality of source driver ICs 131a and 131b constituting the data driver 130 are disposed, and a signal controller 1510 is proposed as a component for providing signals. The signal controller 1510 may be a timing controller itself or may be a component including a timing controller, a memory, a lookup table, and the like. In FIG. 14 , for convenience of description, the timing controller 1510 controls the memory controller 1520 to read and write data from the memory 1530 . In addition, the memory controller 1520 controls RGB data provided from the outside or by the timing controller 1510, and the timing controller 1510 may refer to the lookup table 1550 for line overdriving in the previous RGB data and the current RGB data depending on whether the polarity is changed. Then, modulated RGB data is provided to the plurality of source driver ICs 131a and 131b described above, and signals are applied to the plurality of gate driver ICs 121a and 121b to apply gate signals to corresponding lines.

When step S1591 is applied, the timing controller 1510 may instruct the RGB data of the previous line referred to by the lookup table 1550 to be different depending on whether the polarity is changed. For example, an embodiment in which all RGB data of the previous line is set to 0 gray is included.

When step S1592 is applied, the timing controller 1510 may change the lookup table 1550 used according to whether or not the polarity is changed. For example, an embodiment in which two types of lookup tables are used and different lookup tables are used when the polarity is changed and when the polarity is not changed is included.

Polarity change of S1591 and S1592 can be determined through a data output signal such as POL. Using the configuration of FIG. 14 , a value stored in memory or a lookup table may be selected differently depending on whether the polarity is changed.

When the above-described embodiment is applied, the present invention fixes the data value of the previous line to 0 gray when a polarity change occurs in N-dot inversion driving, thereby solving the weak charging problem in response to the polarity change without a separate lookup table.

When the above-described embodiment is applied, the present invention can solve the weak charging problem in response to the polarity change by using a separate lookup table when a polarity change occurs in N-dot inversion driving.

In constructing the lookup table, if the data of the previous line is fixed to 0 gray or a specific level of gray in the lookup table applied when there is no polarity change, memory usage can be reduced.

When the line overdriving of the present invention is applied, crosstalk or weak charging can be solved even in case of polarity change. When the polarity is changed, it is possible to solve the weak charging problem through overdriving by setting gray to 0 to increase the gray difference value from the previous line or by calculating a compensation value by storing a separate lookup table.

In particular, even when the same gray is maintained between the previous line and the current line during the polarity change process, the gray of the previous line is set to 0 gray or a very low gray value so that the difference in polarity is reflected and charging is performed.

Although the above has been described based on the embodiments of the present invention, various changes or modifications may be made at the level of those skilled in the art. Accordingly, it will be understood that such changes and modifications are included within the scope of the present invention as long as they do not depart from the scope of the present invention.

100: display device 110: display panel
120: gate driver 130: data driver
140: timing controller 1410: inversion signal unit
1420: data output unit 1430: memory

Claims (10)

a display panel in which gate lines and data lines intersect;
a gate driver including a plurality of gate drive integrated circuits for applying signals to the gate line;
a data driver applying a data signal to the data line; and
A first compensation value is calculated from the data signal applied to the first sub-pixel when the polarity is maintained, or the value of the data signal applied to the first sub-pixel is set to 0 or a specific gray in response to the inversion signal unit connected to the first data line and instructing the inversion of the polarity of the data signal of the first sub-pixel connected to the first gate line and the polarity of the data signal of the second sub-pixel connected to the first data line and connected to the second gate line. A display device including a timing controller including a data output unit configured to compensate for the data signal of the second sub-pixel by calculating a second compensation value and outputting the compensated data signal of the second sub-pixel.
According to claim 1,
The first compensation value is calculated from a first lookup table, the second compensation value is calculated from a second lookup table, and a size occupied by the first lookup table in a memory is larger than a size of the second lookup table.
According to claim 2,
The second lookup table sets and stores data signals applied to the first sub-pixel as the same data signal values.
According to claim 1,
The data output unit includes a polarity compensation unit that calculates the second compensation value.
According to claim 4,
The polarity compensation unit calculates the second compensation value for compensating the data signal of the second sub-pixel independently of the data signal applied to the first sub-pixel.
According to claim 5,
The second compensation value is a value calculated by setting the gray value of the first sub-pixel to 0 gray value.
A method for controlling a polarity change by a timing controller in a display panel in which gate lines and data lines are disposed crossing each other, the method comprising:
comparing, by a timing controller, polarities of sub-pixels connected to a first gate line to which a gate signal has been applied immediately among the gate lines and polarities of sub-pixels connected to a second gate line to which a gate signal is to be applied;
when the polarity of the subpixels is maintained as a result of the comparison, compensating, by a timing controller, data signals of the subpixels connected to the second gate line, the polarity of which is connected to the same data line, using a first gray value of a data signal applied to the subpixels connected to the first gate line and the same data line;
when the polarity of subpixels is changed as a result of the comparison, compensating, by a timing controller, data signals of subpixels connected to the same data line and to the second gate line whose polarity is changed using a second gray value in which data signal values of subpixels connected to the first gate line and the same data line are set to 0 or a specific gray value; and
and outputting, by a timing controller, data signals of the compensated sub-pixels to a source driver integrated circuit that controls the data line and applying a gate signal to the second gate line.
According to claim 7,
wherein the second gray value is a 0 gray value.
According to claim 7,
Compensating using the second gray value
compensating by applying the second gray value when the data signals of the sub-pixels whose polarities are changed are smaller than a preset gray value; and
and compensating by applying a third gray value when the data signals of the sub-pixels whose polarity is changed are greater than a preset gray value.
According to claim 9,
wherein the third gray value is lower than the second gray value.

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