KR102132200B1 - Display device and driving method thereof - Google Patents

Abstract

The present invention includes a display panel formed by crossing data lines and gate lines; A scan driver supplying a scan signal to gate lines; A data driver supplying data voltages to the data lines; And determining whether to expand each n-bit image data into k-bit image data greater than n based on values of a plurality of n-bit image data input from the outside, and dither the expanded k-bit image data according to the determination result. It provides a timing controller to output.

Description

Display device and its driving method {DISPLAY DEVICE AND DRIVING METHOD THEREOF}

The present invention relates to a display device and a driving method thereof.

With the development of the information society, the demand for display devices for displaying images is increasing in various forms, and in recent years, liquid crystal displays (LCDs), plasma display panels (PDPs), and organic light-emitting. Various display devices, such as an organic light emitting display device (OLED), are used.

In order to reproduce the actual image that we see on these display devices, we need to express various degrees of luminance. This is called gradation, and the luminance is divided by dividing the stage in the range of the value representing the darkest and the brightest value that can be expressed on the display. Express. For example, in the case of 4-bit data, the luminance level is expressed by dividing the gradation level into 16 levels in the range of the darkest value and the brightest value that can be expressed by the display device, and 256 for 8-bit data. The luminance level is expressed by dividing the gradation level into two levels.

If the luminance difference between each gradation is small, the luminance change perceived from the human perspective is natural, but if the luminance difference is large, the difference (gradation) between gradations is recognized when viewed with the naked eye, thereby deteriorating the gradation expression.

Since the number of gradation levels that can be expressed in a display device depends on hardware processing capabilities such as a driving IC or a circuit, increasing the number of bits in the driving IC also increases the number of bits in the driving data to improve the above-mentioned problems. It should be able to handle it.

However, if the driving IC that processes the data so that the image data is visually implemented cannot process the high bit number of image data, it must be replaced with a new driving IC that can process the high bit number of image data or process the image data. To do this, the circuit design has to be done again, so that the time and cost burdens are largely generated.

It is to provide a display device and a driving method for improving the image quality without changing the existing design structure.

In yet another aspect, an object of the present invention is to provide a display device and a driving method for selectively performing image processing only on a portion requiring detailed image representation.

In order to achieve the above object, in one aspect, the present invention, a data panel and the gate line is formed by the intersection of the display panel; A gate driver supplying scan signals to gate lines; A data driver supplying data voltages to the data lines; And determining whether to expand each n-bit image data into k-bit image data greater than n based on values of a plurality of n-bit image data input from the outside, and dither the expanded k-bit image data according to the determination result. It provides a timing controller to output.

In another aspect, the present invention, a display panel formed by crossing data lines and gate lines; A gate driver supplying scan signals to gate lines; A data driver supplying data voltages to the data lines; And determining whether to expand each n-bit image data to k-bit image data greater than n based on the values of a plurality of n-bit image data input from the outside, and according to the determination result, the first 1 of the n-bit image data is determined. For the value assigned to each bit up to the least significant bit based on the position of the bit having the value, the position is shifted to the upper level, and the value assigned to each bit is allocated to the remaining lower bit as the value is shifted upward. It provides a display device including a timing controller for dithering and outputting.

In another aspect, the present invention, a data input step of receiving image data from the outside; A threshold value determining step of applying a mask and determining whether the mask comparison value calculated based on the image data of the plurality of pixels to which the mask is applied is equal to or less than a predetermined threshold value; A data expansion step of expanding the number of bits of the image data of the plurality of pixels to which the mask is applied by a predetermined number of bits according to the determination result in the threshold determination step; A dithering step of dithering the image data of each pixel expanded in the data expansion step; And a data output step of outputting dithered image data.

As described above, according to the present invention, there is an effect that can increase the efficiency of image processing by selectively enabling detailed image representation for only a partial region of an image.

In addition, according to the present invention, it is possible to reduce the cost of having a driving IC capable of processing high data bits as it is possible to express a more detailed image than the existing circuit without changing the existing design structure. There is.

1 is a system configuration diagram of a display device to which embodiments are applied.
2 is a block diagram illustrating a configuration of a display device according to an embodiment.
3 is a diagram for explaining a method of determining a threshold value for a plurality of pixels to which a mask is applied by a bit expansion determination unit in an embodiment.
4 is an exemplary diagram for explaining a bit expansion determination unit according to an embodiment.
5 is an exemplary diagram illustrating another method of applying a mask in a bit extension determination unit in an embodiment.
6 is a diagram showing a method in a bit extension processing unit in an embodiment.
7 is an exemplary view showing an example of a bit extension processing unit according to an embodiment.
8 is a diagram showing a method in the dithering processing unit in the embodiment.
9 is an exemplary view showing an example of a dither processing unit in an embodiment.
10 is an exemplary view showing an example of a spatiotemporal dither pattern according to an embodiment.
11 is an exemplary diagram showing another method in the bit extension processing unit in the embodiment.
12 is an exemplary view showing a method in the dither processing unit in connection with FIG.
13 and 14 are flowcharts illustrating a method of driving a display device according to an exemplary embodiment.
15 is a block diagram illustrating a configuration of a display device according to another embodiment.
16 is a flowchart illustrating a method of driving a display device according to another embodiment.
17 is a comparison diagram showing gradation levels in a display device according to a prior art and an embodiment.

Hereinafter, with reference to the accompanying drawings, specific content for the practice of the present invention will be described.

It should be noted that in adding reference numerals to the components of each drawing, the same components have the same reference numerals as possible even though they are displayed on different drawings. In addition, in describing embodiments of the present invention, when it is determined that detailed descriptions of related well-known configurations or functions may obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

In addition, in describing the components of the invention, terms such as first, second, A, B, (a), (b), and the like can be used. These terms are only for distinguishing the component from other components, and the nature, order, or order of the component is not limited by the term. When a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected to or connected to the other component, but another component between each component It should be understood that elements may be "connected", "coupled" or "connected". In the same vein, when a component is described as being formed "above" or "below" another component, that component is all formed directly or indirectly through another component in the other component. It should be understood as including.

1 is a system configuration diagram of a display device to which embodiments are applied.

Referring to FIG. 1, the display device 100 may include a timing controller 110, a data driver 120, a gate driver 130, and a display panel 140.

The timing controller 110 is based on external timing signals such as vertical/horizontal synchronization signals (Vsync, Hsync), image data (RGB), and clock signal (CLK) input from the host system 150. The data control signal DCS for controlling and the gate control signal GCS for controlling the gate driver 130 are output. In addition, the timing controller 110 converts the image data RGB input from the host system 150 into a data signal format used by the data driver 120, and the converted image data R'G'B'. Can be supplied to the data driver 120. For example, the timing controller 110 may convert and convert the image data R'G'B' converted to the resolution or pixel structure of the display panel 140 to the data driver 120.

In an embodiment, the timing controller 110 determines whether to expand each n-bit image data to k-bit image data greater than n based on values of a plurality of n-bit image data input from the outside, and to determine Accordingly, the extended k-bit image data is dithered and output.

In addition, the timing controller 110 determines whether to expand each n-bit image data to k-bit image data greater than n based on values of a plurality of n-bit image data input from the outside, and according to the determination result, n Regarding the value assigned to each bit up to the least significant bit based on the position of the bit having the value of 1 for the first time among the video data of the bit, the position is moved upward and the remaining value is shifted as the value assigned to each bit moves upward. It is also possible to convert n-bit image data and output it by dithering similarly to assigning a value to the lower bit and extending it to k-bit.

The timing controller 110 may control the number of bits extended for image data of each pixel to be different according to a gradation value of each of the plurality of pixels belonging to the partial region or a gradation value of a central pixel among the plurality of pixels belonging to the partial region. Specifically, for example, by comparing a gradation value of a corresponding pixel with a predetermined reference gradation value, when the gradation value of the corresponding pixel is lower than the reference gradation value, the number of bits is expanded to a number of bits that are expanded when the gradation value of the corresponding pixel is lower It can be controlled as much as possible.

A more detailed description of the timing controller 110 according to this embodiment will be described later with reference to the accompanying drawings.

The data driver 120 receives the converted video signal R'G'B' in response to the data control signal DCS and the converted video signal R'G'B' input from the timing controller 110. It is converted to a data voltage (data signal or analog pixel signal) that is a voltage value corresponding to a gradation value and supplied to a data line.

The gate driver 130 sequentially supplies a scan signal (gate pulse or scan pulse, gate on signal) to the gate line in response to the gate control signal GCS input from the timing controller 110.

The display panel 140 defines a plurality of pixels at the intersection of the plurality of gate lines GL1 to GLm and the plurality of data lines DL1 to DLn. Each pixel is connected to at least one organic light emitting device including an anode as a first electrode, a cathode as a second electrode, and a light emitting layer, or by switching a liquid crystal between two substrates using a transistor. It may also include a liquid crystal cell to emit light. In other words, the display panel 140 may be an organic light emitting display panel or a liquid crystal display panel, but the present invention is not limited thereto, and any display panel may be used.

2 is a block diagram illustrating a configuration of a display device according to an embodiment.

Referring to FIG. 2, the display device 100 according to an embodiment includes a bit expansion determination unit 210, a bit expansion processing unit 220, and a dithering processing unit 230.

Hereinafter, the bit expansion determination unit 210, the bit expansion processing unit 220, and the dithering processing unit 230 will be described as being included in the timing controller 110, but are not limited thereto, and the bit expansion determination unit 210 At least one component of the and bit extension processing unit 220 and the dithering processing unit 230 may be included in an image processing unit connected to an input terminal of the timing controller 110.

The bit expansion determination unit 210 is used to determine whether a bit expansion for detailed gray scale expression is necessary for a part of the image implemented through the display panel 140, and inputs image data corresponding to a plurality of pixels. A mask is applied to (RGB), and it is determined whether a value calculated based on image data of a plurality of pixels to which the mask is applied is equal to or less than a predetermined threshold. As a result of the determination, when the calculated value is less than or equal to a threshold value, it can be regarded as a region requiring fine grayscale expression, and image data of a plurality of pixels belonging to the corresponding region can be transmitted to the bit expansion processing unit 220.

The bit expansion processing unit 220 expands the number of bits for each of the image data received from the bit expansion determination unit 210, and assigns a value to the extended bit position. That is, when the value calculated according to the determination of the bit expansion determination unit 210 is less than or equal to the threshold, the bit expansion processing unit 220 expands the number of bits of the image data of the plurality of pixels to which the mask is applied by a predetermined number of bits. .

The dithering processing unit 230 performs dithering on the extended image data of each pixel, and outputs the dithered image data.

The dithering processing unit 230 may derive a dither value based on a dither pattern stored in the memory 400 and apply dither values to the extended image data to perform dithering.

Hereinafter, operations in the bit expansion determination unit 210, the bit expansion processing unit 220, and the dithering processing unit 230 according to the embodiment will be described in more detail with reference to the accompanying drawings.

3 is a diagram for explaining a method of determining a threshold value for a plurality of pixels to which a mask is applied by the bit extension determining unit 210 in the embodiment.

Referring to FIG. 3, the bit expansion determining unit 210 according to an embodiment uses a mask as a method for selecting pixels to perform bit expansion. When a mask M of a predetermined size, for example, an nXn size (n is a natural number) is applied to a plurality of pixels (A region) input to the timing controller 110, (0,0) position of the mask M Pixels corresponding to to pixels corresponding to the (n,n) position may be designated as one pixel group for threshold determination.

The bit expansion determination unit 210 compares the image data of the pixels corresponding to each position of the mask M and the threshold value, and according to the comparison result, the image data of the pixels corresponding to the mask M is the bit expansion processing unit 220 ).

For convenience of description, a value calculated from image data of pixels corresponding to each position of the mask M for comparison with a threshold value is referred to as a mask comparison value.

The bit extension determining unit 210 may calculate a difference between the average value of the image data of the central pixel and the image data of the remaining pixels among the plurality of pixels to which the mask M is applied as a mask comparison value. In addition, when the calculated mask comparison value is compared with a preset threshold value, when the mask comparison value is equal to or greater than the threshold value, image data of the pixels to which the mask M is applied may be output as it is. Further, when the calculated mask comparison value is compared with a preset threshold value, when the mask comparison value is less than or equal to the threshold value, the image data of the pixels to which the mask M is applied is transferred to the bit extension processing unit 220, and Let the number of bits expand.

Also, the bit expansion determination unit 210 may calculate an average value of image data of a plurality of pixels to which the mask M is applied as a mask comparison value. In addition, when the calculated mask comparison value is compared with a preset threshold value, when the mask comparison value is equal to or less than the threshold value, image data of the pixels to which the mask M is applied may be transferred to the bit expansion processing unit 220.

The present invention aims to reduce the level difference between gradations, so that detailed expression is possible, so that the mask comparison value and the threshold value in the bit expansion determination unit 210 according to the embodiment are similar to the plurality of pixels to which the mask M is applied. Alternatively, it can be regarded as a value for determining whether it has the same gradation value, and accordingly, the threshold value may be set differently according to a method of calculating a mask comparison value.

4 is an exemplary diagram for explaining the bit extension determining unit 210 according to an embodiment, and a case in which a 3X3 sized mask is applied will be described as an example, but the size of the mask is not limited to 3X3.

First, it is assumed that image data of a plurality of pixels with masks applied to regions I1 and I2 appear in one image as I1a, I1b, and I2a.

When the bit expansion determination unit 210 calculates the difference between the average value of the pixels other than the center pixel among the plurality of pixels to which the mask is applied and the image data of the center pixel as a mask comparison value, the image data of the plurality of pixels to which the mask is applied is If it has the same value as I1a, the bit expansion determining unit 210 can calculate an average value of 15.5 other than the image data of the central pixel, 19. At this time, since the mask comparison value is 3.5, when the threshold value is set to 15, the bit expansion determination unit 210 may transmit image data of pixels belonging to I1a to the bit expansion processing unit 220.

In addition, when the image data of the plurality of pixels to which the mask is applied has a value equal to I1b, the bit expansion determining unit 210 may calculate an average value of 351.25 of the remaining image data except for the image data 362 of the central pixel. At this time, since the mask comparison value is 10.75, when the threshold value is set to 15, the bit expansion determination unit 210 may transmit image data of pixels belonging to I1b to the bit expansion processing unit 220.

However, when the image data of the plurality of pixels to which the mask is applied has the same value as I2a, the bit expansion determination unit 210 according to the embodiment calculates an average value of 172.25 of the remaining image data except for the image data of 95 of the central pixel. Can. At this time, since the mask comparison value is 77.25, the bit expansion determination unit 210 may output image data belonging to I2a to the bit expansion processing unit 220 without being transmitted to the outside.

Meanwhile, when the bit expansion determination unit 210 calculates the average value of the image data of all the pixels to which the mask is applied as a mask comparison value, if the image data of the plurality of pixels to which the mask is applied has the same value as I1a, the bit expansion determination unit ( 210) may calculate 15.89 as a mask comparison value. When the threshold value is set to 20, since the mask comparison value is less than or equal to the threshold value, the bit expansion determination unit 210 may transfer the image data of I1a to the bit expansion processing unit 220.

When the image data of the plurality of pixels to which the mask is applied has a value equal to I1b, the bit expansion determination unit 210 may calculate 352.44 as a mask comparison value. Therefore, the bit expansion determination unit 210 does not transmit the image data of I1b to the bit expansion processing unit 220 because the mask comparison value is greater than the threshold value.

However, when the average value of the image data of all the pixels with the mask applied to the image data of I1b is calculated as a mask comparison value, the bit expansion determination unit 210 may set the image data value of the central pixel as a threshold value of the mask. In this case, since the calculated mask comparison value 352.44 is smaller than the central pixel image data value 362, the image data of I1b may be transferred to the bit extension processor 220.

In addition, when the image data of a plurality of pixels to which the mask is applied has the same value as I2a, the bit expansion determination unit 210 may calculate 163.67 as a mask comparison value, wherein the mask comparison value of 163.67 is the image data of the central pixel. Since the value is greater than 95, the image data of I2a may not be transmitted to the bit extension processor 220, which masks the difference between the average value of the remaining pixels except the center pixel and the image data of the center pixel among the plurality of pixels to which the mask is applied. It is the same as the result in the case of calculating with a comparative value.

The bit expansion determination unit 210 may repeat the operation of determining whether to expand the bit by applying a mask until it is applied to all pixels of the display panel 140, as described above, the threshold value of the image data of the central pixel If set to, it may be set differently according to the image data values of the pixels applied to the mask.

As described above, the operation of the bit expansion determination unit 210 has been described as an example, but this is only an exemplary method, and various methods for determining whether a plurality of pixels with masks have similar or identical gradation values are described. Method can be applied.

The size of the mask applied to the pixels in order to determine whether the bit expansion of the plurality of pixels is extended by the bit expansion determination unit 210 is determined in advance as 3X3 or 5X5, nXn, 4X3, 4X6, etc. as described above. It can be repeatedly applied until it is determined whether to expand the bit.

Also, the size of the mask may vary depending on image data of a plurality of pixels to which the mask is applied.

5 is an exemplary diagram illustrating another method of applying a mask in the bit extension determining unit 210 in the embodiment.

In order to determine the size of the mask, the bit expansion determining unit 210 may select any one pixel for applying the mask as a center pixel among all pixels of the display panel. The bit expansion determining unit 210 calculates a difference value between the center pixel and image data adjacent to (and surrounding the center pixel) and determines whether the calculated difference value is equal to or less than a predetermined reference value. When all of the image data of the pixels adjacent to the central pixel are equal to or less than the reference value, the bit expansion determination unit 210 calculates a difference value between the adjacent pixels and the image data of each of the adjacent pixels, and the calculated difference value is a predetermined reference value. It is judged as follows.

For example, referring to FIG. 5, the bit expansion determination unit 210 may set the reference value to 10 and select an arbitrary pixel as the center pixel P0. Also, the bit expansion determining unit 210 calculates a difference value of image data between the pixel P0 selected as the center pixel and the pixels P1-P8 adjacent to the center pixel, and the pixels P1-P8 adjacent to the center pixel. Among them, a difference value of image data between adjacent pixels is also calculated. In FIG. 5, the image data value of the center pixel P0 is 61, and the image data values of the pixels P1-P8 adjacent to the center pixel are 58, 60, 65, 63, 60, 57, 58, 59, and 58. to be. Since the difference value between the pixels adjacent to each other among the pixels P1-P8 adjacent to the center pixel does not exceed the reference value of 10, and the difference value between the pixels adjacent to the center pixels P1-P8 does not exceed the reference value of 10, bit The expansion determining unit 210 then calculates a difference value between the image data of adjacent pixels with respect to the image data of adjacent pixels P9-P24.

As a result of calculation, next, adjacent pixels have a difference value between the adjacent pixels and the image data all exceed the reference value of 10, and some pixels are different from each other (P12-P13, P17-P18, P19-P20). The difference is over 10. In this case, the bit expansion determining unit 210 determines the size of the mask by applying the mask only to the pixels P1-P8 adjacent to the center pixel P0, which is determined to have a difference between image data less than a reference value.

That is, as illustrated in FIG. 5, when a 3X3 sized mask centered on the center pixel P0 is determined according to a difference value of image data, it is determined whether or not the masked pixels are transferred to the bit expansion processor 220. Then, the size of the mask may be determined and applied again to the remaining pixels whose bit expansion is not determined based on the image data.

6 is a diagram illustrating a method in the bit extension processing unit 220 in the embodiment.

Referring to FIG. 6, the bit expansion processing unit 220 may expand data bits by adding a predetermined number of bits to the image data received from the bit expansion determination unit 210.

That is, when the n-bit image data is transmitted from the bit expansion determination unit 210, the bit expansion processing unit 220 adds m bits to the received n-bit image data to receive (n+m)-bit image data. (N,m is a natural number)

The bit extension processing unit 220 may generate (n+m)-bit image data by adding m bits to the least significant bit of the n-bit image data. First, 0 may be allocated as a data value to the added m bits. have. For example, 3 bits may be added to 8-bit image data of 10101100 to make 10101100_000.

The m-bit value added to the n-bit image data may be set to apply a fixed value to the image data of all received pixels.

Also, the value of m-bit added to the image data of n-bit may be set differently according to the number of bits of image data input so that (n+m) has a fixed value.

Also, the value of m-bit added to the image data of n-bit may be set differently according to the value of the image data of each pixel received. That is, the bit expansion processing unit 220 adds m1 bits to the (n+m1) bits when the image data of the received pixel is less than or equal to a preset reference gradation value, and has a different value from m1 when the reference gradation value is exceeded. It can be extended to (n+m2) bits by adding m2 bits. In this case, when a large number is set as the reference gradation value, the number of bits of different values may be added to each reference gradation value range to be extended.

In this case, it is assumed that the image data value of each pixel in this specification has the same value as the gradation value of the corresponding pixel.

In general, since the gray level difference recognized by the human eye is recognized more clearly in the low gray level than in the high gray level, the bit expansion processing unit 220 according to the embodiment determines that the received image data value is low gray level It is also possible to perform bit expansion.

That is, when the received image data value exceeds the reference grayscale value, the bit expansion processing unit 220 determines that the corresponding pixel is not low grayscale and outputs it without performing bit expansion, and the received image data value is the reference When the value is less than the gradation value, it is determined that the corresponding pixel is low gradation, and thus the image data can be expanded by a predetermined number of bits.

In addition, the bit expansion processing unit 220 according to the embodiment may vary the number of bits to be expanded according to whether the received image data value is low gray level or high gray level.

That is, when the received image data value is less than or equal to the reference gradation value, m1 bits are added to expand the image data. When the received image data value exceeds the reference gradation value, m2 bits (m1>m2, m1, and m2) Image number) to expand the image data.

If the above-described methods are described as an example, the bit expansion processing unit 220, if m=5, adds 5 bits to all image data received from the bit expansion determination unit 210 (n+ 5) The bit data can be expanded.

In addition, when (n+m)=16, the bit expansion processing unit 220 sets the number of bits to be added if the image data received from the bit expansion determination unit 210 is 8 bits (n=8). m=8), and if the received image data is 10 bits (n=10), the number of added bits may be 6 (m=6).

In addition, if the image data of the received pixel is less than or equal to a preset reference gradation value, the bit expansion processing unit 220 determines that it is low gradation and adds 5 bits to expand it to (n+5) bits, and when it exceeds the reference gradation value Judging by the high gradation, it is possible to output the image data without expanding it.

In addition, if the image data of the received pixel is less than or equal to a preset reference gradation value, the bit expansion processing unit 220 determines that it is low gradation and adds 5 bits to expand it to (n+5) bits, and when it exceeds the reference gradation value Judging by the high gradation, 2 bits can be added to expand to (n+2) bits.

The bit extension processing unit 220 according to the embodiment considers a change in luminance value according to the number of bits of the image data, and the number of bits added (n+m), which is the number of bits of the expanded image data, has a value of at least 11 or more. You can decide.

The following Table 1 is a table in which the change of the luminance value according to the increase of the gradation value of the low gradation is presented for each bit of the image data in a state where the contrast ratio is the same.

As shown in Table 1, in 8-bit image data, the average luminance value increases by approximately 0.04 nits as the gradation value increases by one. In the case of a display device capable of realizing a high-resolution image such as an organic light emitting display device, in order to not recognize a gradation level difference in a low gradation region, a luminance change according to gradation should be expressed as 0.001 nit or less.

For 10-bit image data, the luminance value increases by an average of about 0.002 nits as the gradation value increases by 1, and for 16-bit image data, the luminance value increases by an average of about 0.0000002 nits as the gradation value increases by 10 bits. The following image data may be extended to image data having a bit higher than 10 bits, so that a detailed and natural gradation expression can be achieved.

The bit expansion processing unit 220 may assign a value to the added lower bit in each of the expanded image data and output the dividing processing unit 230.

At this time, the bit expansion processing unit 220 may allocate a value to the lower bit based on the image data values of the plurality of pixels received from the bit expansion determination unit 210, the plurality of masks applied by the bit expansion determination unit 210 A value may be assigned according to the relationship of the image data value of each of adjacent pixels or next adjacent pixels based on the image data value of the central pixel among the pixels.

7 is an exemplary diagram showing an example of a bit expansion processing unit 220 according to an embodiment, and a case of expanding 10-bit image data to 16 bits will be described as an example.

Referring to FIG. 7, the bit expansion processing unit 220 may receive image data values of a plurality of pixels, such as I1a, from the bit expansion determination unit 210.

When the image data inputted to the timing controller 110 is 10-bit image data, the image data of the center pixels and pixels arranged on the left and right of the center pixel may be expressed as 0000010100, 0000010011, and 0000010001. The bit expansion processing unit 220 adds 6 bits to each of 0000010100, 0000010011, and 0000010001 so that the image data received from the bit expansion determination unit 210 is allocated to the upper 10 bit positions of 16 bits, 0000010100_xxxxxx, 0000010011_xxxxxx, It can be made as 0000010001_xxxxxx.

The bit expansion processing unit 220 allocates a value to the added 6 bits, and the image data value of the left pixel is greater than the image data value of the center pixel based on the center pixel, and the image data value of the right pixel is image data of the center pixel. Less than the value

Therefore, the bit expansion processing unit 220 allocates the minimum value of 000001, which is 6 bits, to the added low bit of the extended image data of the right pixel, and the maximum value, 111111, to the added low bit of the extended image data of the left pixel. Can be assigned. Also, in the range between 000001 and 111111, 011111, an intermediate value, may be allocated to the added lower bit of the extended image data of the central pixel.

In addition, in case of assigning a value by adding 6 bits to the image data of 9 pixels of I1b, since the image data of the pixel located in the upper left of the center pixel has the lowest value, the minimum value of 6 bits is assigned to the pixel. 000001 is allocated to the lower bit, and since the image data of the pixel located at the left of the center pixel has the highest value, the maximum value of 111 bits, which is 6 bits, can be allocated to the lower bit. In addition, for the remaining image data having an intermediate value, values such as 000111, 011111, and 111000 may be allocated to lower bits in a range between 000001 and 111111 according to the relationship of the size of the image data.

The (n+m)-bit image data extended by the bit expansion processing unit 220 is transmitted to the dithering processing unit 230. The dithering processing unit 230 dithers the data received from the bit expansion processing unit, that is, the expanded image data and outputs the dithered data.

Dithering is a method for expressing more gradations than the gradation display capability that can be processed by the data driver 120 in hardware, for example, in a display device that processes 8-bit image data, a 10-bit image It means that the gradation can be expressed to the extent that it is expressed in a display device that processes data.

The image data expanded by the bit extension processing unit 220 is for allowing the gradation to be expressed more precisely than the gradation of the input image data, and the number of bits of the expanded image data exceeds the number of bits that can be processed by the data driver 120. In this case, the gray level in the extended image data is not properly expressed, so in the embodiment, the gray level in the extended image data can be expressed as it is while outputting the bit number of image data processable by the data driver 120 through dithering. To make.

In other words, when the number of bits that can be processed by the data driver 120 is q, the dither processing unit 230 according to the embodiment outputs (n+m)-bit image data as q-bit image data, while (n+ m) It is possible to express the gradation as much as the video data of the bit.

8 is a diagram showing a method in the dithering processing unit 230 in the embodiment.

Referring to FIG. 8, the image data A transferred from the bit expansion processing unit 220 to the dithering processing unit 230 is a bit (the same value as the (n+m) bit described above, but is referred to as a bit for convenience). Wherein, when the number of data bits that can be processed by the data driver 120 is q bits, the dithering processing unit 230 transmits the received a-bit image data by q high bit (A1) and r low bit (A2). The value can be divided by.

If the value of the upper bit (A) of q corresponding to the number of data bits that can be processed by the data driver 120 is called the first bit value, and the value of the lower bit (B) of r is the second bit value, The dithering processing unit 230 may output new q-bit image data by determining a dither value based on the second bit value and reflecting the dither value.

For example, when the image data received from the dithering processing unit 230 is 16 bits, and the data bits that can be processed by the data driving unit 120 are 10 bits, the dithering processing unit 230 is the value of the lower 6 bits among the 16 bits. Based on the determination of the dither value, and reflecting the determined dither value to the value of the upper 10 bits, a new 10-bit that can be expressed in the same or approximate to the gradation value of the 16-bit image data received from the bit expansion processor 220. The data A'can be output.

In the display device according to the embodiment, when the number of bits of image data input to the timing controller 110 and the number of data bits that can be processed by the data driver 120 are the same, the value of the bit added by the bit expansion processing unit 220 It may be determined as a second bit value.

Referring to FIG. 6 described above, the bit expansion processing unit 220 adds a bit to the lower order of the least significant bit of the input image data, and the dithering processing unit 230 uses the value of the lower bit to set the value of the upper bit. When the number of bits of image data input to the timing controller 110 is the same as the number of data bits that can be processed by the data driver 120, the dithering processing unit 230 dithers the value of the bit added by the bit expansion processing unit 220. It can also be seen as being used for.

That is, the input image data is n-bit, the number of data bits that can be processed by the data driver 120 is n-bit, and the m-bit is added by the bit expansion processing unit 220, so that (n+m) bits are dithered processing unit 230 When it is transmitted to, the dithering processing unit 230 determines the value of the lower m bit as the second bit value for the received (n+m) bit image data, and determines the dither value to the value corresponding to the upper n bit. To reflect.

In addition, the dithering processing unit 230, regardless of the number of bits of the image data input to the timing controller 110, the number of bits of the image data received from the dithering processing unit 230 and data bits that can be processed by the data driver 120 The second bit value may be determined according to the number.

For example, when the number of data bits that can be processed by the data driver 120 according to the embodiment is 10 bits, 8-bit image data is input to the timing controller 110 and 8 bits are added from the bit expansion processor 220. When the data extended to the 16-bit image data is transmitted to the dither processing unit 230, the dither processing unit 230 determines the upper 10 bits of the 16 bits as the first bit, and the lower 6 bits of the 16-bit image data are the second Decide with a bit.

In addition, 10-bit image data is input to the timing controller 110 and 6 bits are added from the bit expansion processing unit 220 so that the data extended to the 16-bit image data is transmitted to the dither processing unit 230, so that the dithering processing unit ( 230) may determine the upper 10 bits of the 16 bits as the first bit and the lower 6 bits of the 16-bit image data as the second bit.

9 is an exemplary view showing an example of the dithering processing unit 230 in the embodiment.

Referring to FIG. 9, the dithering processor 230 according to an embodiment may view adjacent pixels as a group and display pixels belonging to a group in order to express more gradations than the gradation display capability processable by the data driver in hardware. The gradation can be subdivided into time or space. Accordingly, the dithering processing unit 230 may apply a dither mask having a predetermined size to the image data of the plurality of pixels received from the bit expansion processing unit 220 to process the dithering using a plurality of masked pixels as a group. At this time, the dither mask may have the same size as the mask used in the bit expansion determination unit 220, but is not limited thereto and may be set to a different size.

The dithering processing unit 230 may classify 4 horizontally and 4 vertically 16 pixels among pixels adjacent to each other among a plurality of pixels received from the bit expansion processing unit 220. The dithering processing unit 230 determines a value corresponding to the upper q bit for each pixel in the group as a first bit value, and a value corresponding to the lower r bit as a second bit value. In addition, the dithering processing unit 230 generates a first bit group using the first bit values of each pixel in the group, and a second bit group using the second bit values of each pixel in the group. can do.

For convenience of description, it will be described as an example that pixels belonging to column 1 of the pixels belonging to this group have image data values of A, B, C, and D, respectively, and the second bit is 3 bits.

The dithering processing unit 230 may determine A1, B1, C1, and D1 belonging to the first bit group for each of A, B, C, and D, and determine A2, B2, C2, and D2 belonging to the second bit group. have.

The dithering processing unit 230 may select one of a plurality of dither patterns stored in the memory 400 based on the second bit value, and determine a dither value from the selected dither pattern.

That is, in FIG. 9, the dithering processing unit 230 selects one of the plurality of dither patterns DP1-DP8 using the values of A2, B2, C2, and D2. When 3 bits are allocated as the second bit, the second bit value can vary from 0 to 7 as a decimal value, and 8 values are possible. Accordingly, when 3 bits are allocated as the second bit, 8 dither patterns may be utilized, and when q bits are allocated as the second bit, as many as 2 ^q dither patterns may be utilized.

For example, when A2="1", B2="3", C2="4", D2="0", the dithering processing unit 230 corresponds to A2 among the eight dither patterns. The dither pattern DP2 can be selected, the fourth dither pattern DP4 can be selected in response to B2, the fifth dither pattern DP5 can be selected in response to C2, and the first dither pattern is corresponding to D2 (DP1) can be selected. As described above, each value belonging to the second bit group may be used to select a dither pattern.

The dithering processing unit 230 may again select one of each value of the selected dither pattern using the values of A2, B2, C2, and D2. To this end, the dithering processing unit 230 may select a value by matching the position of the second bit value in the second bit group with the position in the selected dither pattern.

That is, in FIG. 9, the dithering processing unit 230 may select the second dither pattern DP2 based on the value of A2, and use A2 in the position of (0,0) in the second bit group. In the second dither pattern DP2, 1, which is a value at (0,0), may be determined as a dither value for reflecting A1.

Further, the dithering processing unit 230 may select the fifth dither pattern DP5 based on the value of C2, and the fifth dither pattern using C2 in the position of (0,3) in the second bit group In (DP5), the value at position (0,3) of 1 can be determined as a dither value to reflect to C1.

Similarly, in the fourth dither pattern DP4 selected based on the value of B2, the dither processing unit 230 may determine a value corresponding to (0,2) of B2 as a dither value to reflect in B1. In the first dither pattern DP1 selected based on the value of D2, a value corresponding to (0,4) of D2, 0, may be determined as a dither value for reflecting in D1. In this way, the dither processing unit 230 may determine the dither value for each of the image data of 16 pixels belonging to one group.

The dither processing unit 230 selects a dither value by matching the position in the second bit group with the position in the selected dither pattern, so that the size of the dither mask can match the size of the dither pattern.

When the dither value 1 is determined for A, the dithering processing unit 230 may add 1 to A1 of the first bit group and output q-bit new image data.

Therefore, if A1 has a value of 17 as a decimal number, the new image data output has a value of 18, and when B1 has a value of 51, the new image data output has a value of 51, and C1 has a value of 5. If it has, the new image data output has a value of 6, and when D1 has a value of 60, the new image data output has a value of 60.

The above-described dithering processing unit 230 is a description of a method for performing spatial dithering using image data of adjacent pixels, and may perform temporal dithering as well as spatial dithering.

In an embodiment, temporal dithering is simply expressed by applying dither values differently for each frame. To this end, the dither processing unit 230 may change the value of each of the plurality of dither patterns stored in the memory 400 over time.

10 is an exemplary view showing an example of a spatiotemporal dither pattern according to an embodiment, and is a diagram illustrating a change in the dither pattern when temporal dithering is performed in 4 frames.

Referring to FIG. 10, the dithering processing unit 230 may perform dithering in the first frame T0 based on the dither pattern as illustrated in FIG. 9. Next, in the second frame T1, the dithering processing unit 230 performs dithering based on the dither pattern in which the position of each bit value of the dither patterns applied in the first frame T0 is moved. In FIG. 10, each bit position of the dither patterns may be rotated clockwise with time, and the dither patterns may be divided into a left upper quadrant, a right upper quadrant, a lower right quadrant, and a lower left quadrant, and each quadrant is 4 bits. It may include.

The dithering processing unit 230 may move the bit value clockwise with respect to each of the quadrants. For example, in the first frame T0, the left upper quadrant of the second dither pattern DP2 (0, 1, a value located at 0), is moved from the second frame (T1) to (0,1), is moved from the third frame (T2) to (1,1), and (1, from the fourth frame (T3)) 0). In addition, the value of the (0,0) position of the second dither pattern is changed to 1-0-0-0 from the first frame T0 to the fourth frame T3 according to the position movement. Accordingly, when dithering A based on the second dither pattern, the dither processing unit 230 adds 1 to A1 in the first frame T0, adds 0 to A1 in the second frame T1, and the third frame. In (T2), 0 may be added to A1, and in the fourth frame T3, 0 may be added to A1 to output new image data.

Similarly, a value of 1 located at (0,0) in the upper left quadrant of the fifth dither pattern DP5 in the first frame T0 is moved from the second frame T1 to (0,1), and the third It is moved from the frame T2 to (1,1), and from the fourth frame T3 to (1,0). Accordingly, the value of the (0,0) position in the fifth dither pattern DP5 is changed from 1st frame T0 to the 4th frame T3 from 1-0-1-1. Therefore, the dithering processing unit 230 adds 1 to C1 in the first frame T0 and 0 to C1 in the second frame T1 when dithering C based on the fifth dither pattern DP5, In the third frame T2, 1 may be added to C1, and in the fourth frame T3, 1 may be added to C1 to output new image data.

In the above-described embodiment, it has been described that the bit expansion processing unit 220 generates extended image data by adding as many bits as desired. Hereinafter, another method of achieving an effect similar to that of data bits being expanded while minimizing the number of bits that are substantially added will be described.

When the 10-bit image data value transmitted to the bit extension processing unit 220 is 21 or less or 53 or less in decimal, it is 0000011111 or 0000111111 when it is expressed in binary. If the image data value is 21, the upper 5 bits have a value of 0, and if the image data value is 53, the upper 4 bits have a value of 0. Another method in the embodiment is to use a higher number of bits having a value of 0, by shifting 11111 of the lower 5 bits having a substantial value to the upper level and assigning a value to the remaining 5 lower bits as the bit value moves. It is possible to obtain an effect similar to the expansion of the 10-bit image data transmitted to the expansion processing unit 220 to 15 bits.

11 is an exemplary diagram showing another method in the bit extension processing unit 220 in the embodiment.

As shown in FIG. 11, when 0000010011, which is 10-bit image data having a value of 19 as a decimal number, is input to the bit extension processing unit 220, the image data is moved up one bit by one bit until the value of the most significant bit becomes 1. Order. That is, the bit expansion processing unit 220 may move 0000010011 to 0000100110 and move it back to 0001001100, and repeat until the image data according to the bit movement has a value of 10011xxxxx. When the movement is completed, the bit expansion processing unit 220 may calculate the number of upper bits having a value of 0 from the number of times the bit movement is repeated.

The bit expansion processing unit 220 obtains the same effect as extending to 15 bits even if data is not actually generated by allocating values for the lower 5 bits by performing 5 bit movements on the 10 bit image data. Can.

In addition, as illustrated in FIG. 8, when 6 bits are added to expand to 16 bits, only one bit (S) is added to the lower 5 bits so that a value of 6 bits can be allocated, thereby reducing 11 bits. The same effect as that of generating 16-bit data with data can be obtained.

In addition, when 3 bits are added and extended to 13 bits, the same effect as generating 13-bit data can be obtained by allocating the value of the bit to be added next to the rightmost 1, which is the least significant bit of 10011.

The image data whose bits are expanded in the manner described above with reference to FIG. 11 is converted into new data through the dithering processing unit 230.

12 is an exemplary view illustrating a method in the dithering processing unit 230 in connection with FIG. 11.

Referring to (a) of FIG. 12, the dithering processing unit 230 performs dithering on the image data received from the bit expansion processing unit 220 based on the value of the lower 6 bits.

Referring to (b) to (d) of FIG. 12, as a result of completing dithering, when a new data value is allocated to the upper 5 bits of the 11 bits received from the bit expansion processing unit 220, it is allocated to the upper 5 bits. The data value is shifted one bit to the right. When the number of bits that can be processed by the data driver is 10, the least significant bit of 11 bits may be deleted to make 10 bits of data. The dithering processing unit 230 moves the data value allocated to the upper 5 bits by one bit to the right for 10 bits, and the value of the 5th bit, which is the least significant bit of the values of the 5th highest bit, is the 10th bit, which is the least significant bit of 10 bits. When assigned to, stop moving the bit.

Referring to (e) of FIG. 12, 10 bits of image data can be generated by assigning 0 to the upper 5 bits whose value is not defined as the upper 5 bits move to the lower side.

The display device according to the embodiment as described above is driven as follows.

13 and 14 are flowcharts illustrating a method of driving a display device according to an exemplary embodiment.

Referring to FIG. 13, a method of driving a display device according to an embodiment includes a data input step (S110) of receiving image data from the outside and a mask calculated based on image data of a plurality of pixels to which a mask is applied and a mask is applied. A threshold value determining step (S120) for determining whether a value is equal to or less than a predetermined threshold value, and a predetermined number of bits of the number of bits of image data of each of the plurality of pixels to which the mask is applied according to the determination result in the threshold value determining step It includes a data expansion step (S130) to expand, a dithering step (S140) to perform dithering on the image data of each pixel expanded in the data expansion step, and a data output step (S150) to output the dithered image data. .

In the threshold value determining step (S120 ), a mask of a predetermined size is applied to a plurality of pixels adjacent to each other, and a mask comparison value is calculated based on image data of the plurality of pixels to which the mask is applied. Comparing the calculated mask comparison value with a predetermined threshold value, when the calculated mask comparison value is less than or equal to the predetermined threshold value, proceeds to the data expansion step, and when the calculated mask comparison value exceeds the threshold value, the data input step. Outputs the image data received in the format without expanding the number of bits (S160).

In the data expansion step (S130 ), when it is determined that the calculated mask comparison value is equal to or less than a threshold value, a predetermined number of bits are added to the least significant bit side of each image data of a plurality of pixels applied to the mask, and the number of bits of the image data is increased. Can be increased.

In the data expansion step (S130 ), the number of bits added may vary according to the value of each image data of a plurality of pixels.

Referring to FIG. 14, the data expansion step (S130) compares the image data value with the reference grayscale value. (S210) As a result of comparison, the first bit preset for image data determined to have an image data value equal to or less than the reference grayscale value. The number of bits of the image data is increased by adding as many bits as possible (S230).

In addition, the number of bits of the image data is increased by adding bits to the set number of second bits different from the first number of bits for the image data determined to have exceeded the reference gradation value. (S240)

Next, the extended image data is generated by allocating values to bits added to the image data in steps S230 and S240 according to the relationship between the image data values between adjacent pixels. (S250)

Meanwhile, in step S140, dithering is performed on the image data extended by a predetermined number of bits. Thereafter, the image data dithered in step S150 is output to the outside.

The dithering step (S140) selects one of a plurality of dither patterns stored in the memory 400 based on the values of the lower partial bits of the extended image data, and sets the dither values determined based on the selected dither patterns to the upper bits of the expanded image data. It can be done by reflecting on.

On the other hand, in the display device according to the above-described embodiment, dithering is performed after the number of bits is expanded for detailed gradation expression only for image data having a mask comparison value equal to or less than a threshold value, but the mask comparison value exceeds a threshold value. For data, more gradations may be expressed than input image data.

15 is a block diagram illustrating a configuration of a display device according to another embodiment.

15, the display device according to another embodiment includes a first image data converter 200, a second image data converter 300, and a memory 400. The first image data conversion unit 200 includes a bit expansion determination unit 210 and a bit expansion processing unit 220, and the second image data conversion unit 300 includes a smooth area determination unit 310 and a dithering processing unit 320. ). In the display device according to another embodiment, since the bit expansion determination unit 210 and the bit expansion processing unit 220 of the first image data conversion unit 200 may operate in the same manner as in the above-described embodiment, detailed The description is omitted, and only in the case where it operates differently from the exemplary embodiment will be described in detail.

The smoothing area determining unit 310 determines whether pixels having the same image data value are adjacent to each other or a region in which a difference in image data values between adjacent pixels exists is minimal.

The bit expansion determination unit 210 is a method for selecting pixels to expand the number of bits, and determines whether adjacent pixels have similar image data values. The smaller the size of the mask, the more accurate it is to judge whether the image data values are similar for a small number of pixels.However, it is necessary to repeat a series of processes of applying a mask and calculating a mask comparison value and comparing it with a threshold value. Therefore, it may take a relatively long time to complete the above-described process for all pixels of the display panel.

The bit expansion determining unit 210 needs to determine whether the image data value is similar for a large number of pixels as the size of the mask increases, so it takes relatively little time to complete the above process for all pixels of the display panel. Can. However, the image data values have similar values and pixels adjacent to each other may exist as regions smaller than the size of the mask.

Accordingly, the smooth area determining unit 310 receives image data of a plurality of pixels determined by the bit expansion determining unit 210 to exceed the threshold value, and sets any pixel as a center pixel, The difference value between the image data value of the pixels close to the pixel and the image data value of the central pixel is calculated.

When the difference value exceeds a predetermined smoothing reference value, the smoothing area determining unit 310 determines that the corresponding pixels are pixels that should be expressed so that a gradation difference is clearly displayed, for example, pixels at a position where a boundary should be expressed. The image data is output as it is.

When the difference value is less than or equal to the smoothing reference value, the smoothing area determining unit 310 repeats the same process with respect to other pixels that are close to the corresponding pixels, but is closer to the central pixel and less than the image data value and smoothing reference value of the central pixel. The difference between the image data value of other pixels and the image data value of the center pixel is calculated by using at least one pixel having a difference as the second center pixel, and other pixels at a distance close to the second center pixel.

When the difference value is less than or equal to the smoothing reference value, the smoothing area determining unit 310 is close to the second central pixel and has at least one pixel that differs from the image data value of the central pixel and the smoothing reference value or less as the third central pixel. , The difference value between the image data values of other pixels at a distance close to the third central pixel and the image data values of the central pixel may be calculated and compared with a smoothing reference value.

The smoothing area determining unit 310 may repeat the above operation to select a plurality of pixels (smoothing areas) having the same or similar values to the image data of the central pixel, and the dividing processing unit ( 230).

Also, the smooth area determining unit 310 may have a small number of pixels that are determined to have the same or a similar value to the image data of the central pixel, such that they are not recognized as being aggregated when viewed with the naked eye (for example, 10). Hereafter) or if they are arranged (for example, when the corresponding pixels are arranged in a line), the image data of the corresponding pixels may be output as they are without being transmitted to the dithering processing unit 230.

The dithering processing unit 320 performs dithering on the image data received from the smooth area determining unit 310 and outputs the dithered image data. At this time, since the image data input to the dithering processing unit 320 is not the expanded image data, the dither pattern is selected based on the value of the lower bit of the input image data, and the dither value is selected from the selected dither pattern to input the image data. Dithering may be performed by reflecting the value of the least significant bit of.

16 is a flowchart illustrating a method of driving a display device according to another embodiment.

Referring to FIG. 16, a method of driving a display device according to another embodiment includes a data input step (S310) of receiving image data from the outside and a mask calculated based on image data of a plurality of pixels to which a mask is applied and a mask is applied. A threshold value determining step (S320) for determining whether the comparison value is equal to or less than a predetermined threshold value, and a number of bits of image data of each of the plurality of pixels to which the mask is applied according to the determination result in the threshold value determination step (S320) are previously determined. A data expansion step (S330) of expanding a predetermined number of bits, and a smooth area determination step (S340) of determining whether a plurality of pixels to which the mask is applied forms a smooth area when the mask comparison value exceeds a threshold value; , Dithering step (S350) for dithering the image data of the pixels extended in the data expansion step (S330) or the pixels of the pixels determined to form a smooth area in the smoothing region determination step (S350), and the dithered image data It includes a data output step of outputting (S370).

In each step, the remaining steps except for the smooth area determining step (S340) and the dithering step (S350) are performed in the same manner as in the above-described exemplary embodiment, so detailed descriptions of these steps are omitted.

In the smooth area determining step S340, the image data of a plurality of pixels determined to have a mask comparison value exceeding the threshold value is transmitted in the threshold value determining step S320, and an arbitrary pixel is used as the central pixel, and The difference between the image data values of the pixels at a close distance and the image data values of the central pixel is calculated.

In the case of pixels in which the difference value exceeds a predetermined smoothing reference value, image data of the corresponding pixels is output as it is (S360), and the image data of the pixels determined to be equal to or less than the smoothing reference value is dithered (S350). Go over

In the dithering step S350, dithering is performed on pixels in an area determined to be a smoothing area in the smoothing area determining step S340, and a dither pattern is selected based on the value of a lower bit for each image data of the corresponding pixels. And dithering may be performed by selecting a dither value from the selected dither pattern and reflecting the value of the least significant bit of the corresponding image data.

FIG. 17 is a comparison diagram showing gradation levels in a display device according to the prior art and embodiments, and FIG. 17(a) is a diagram showing gradation patterns in a conventional organic light emitting display device, and FIG. 17(b) ) Is a diagram showing a gradation pattern in an organic light emitting display device according to an embodiment of the present invention.

When comparing (a) and (b) of FIG. 17, the gradation pattern in the conventional display device has the same interval between each gradation level, and at low gradations, the luminance change as the gradation level increases is perceived by the naked eye. appear.

On the other hand, in the gray scale pattern in the display device according to an embodiment, the interval between each gradation level is narrow in the low gradation and wide in the gradation, and as the gradation level is expressed in a lower gradation than in the gradation, It can be seen that the luminance change caused by the increase in the gradation level is not perceived as in the prior art, so that it is possible to express the gradation in a lower gradation than the conventional one.

The terms "include", "compose" or "have" as described above mean that the corresponding component can be inherent unless otherwise stated, and do not exclude other components. It should be interpreted that it may further include other components. All terms, including technical or scientific terms, unless otherwise defined, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Commonly used terms, such as predefined terms, should be interpreted as being consistent with the meaning of the context of the related art, and are not to be interpreted as ideal or excessively formal meanings unless explicitly defined in the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the claims below, and all technical spirits within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

110: timing controller
210: bit expansion determination unit
220: bit expansion processing unit
230, 320: dither processing unit
310: smoothing area determining unit
400: memory

Claims (16)

A display panel formed by intersecting data lines and gate lines;
A gate driver supplying a scan signal to the gate lines;
A data driver supplying a data voltage to the data lines; And
A mask comparison value is applied to a plurality of n-bit image data inputted from the outside, and a comparison result of a mask comparison value and a predetermined threshold value calculated based on the value of the n-bit image data of a plurality of pixels in a partial region to which the mask is applied. In accordance with this, the timing controller determines whether to expand each n-bit image data to k-bit image data larger than n, and dithers and outputs the expanded k-bit image data according to the determination result.
Display device comprising a. A display panel formed by intersecting data lines and gate lines;
A gate driver supplying a scan signal to the gate lines;
A data driver supplying a data voltage to the data lines; And
Based on the value of a plurality of n-bit image data input from the outside, it is determined whether each n-bit image data is expanded to k-bit image data greater than n, and according to the determination result, the first of the n-bit image data is 1 With respect to the value assigned to each bit up to the least significant bit based on the position of the bit having the value of, the position is shifted upward, and the value assigned to the remaining lower bit is allocated as the value assigned to each bit moves upward. Next, the timing controller outputs by dithering.
Display device comprising a. According to claim 2,
The timing controller,
The first bit is repeated until the bit with the value of 1 moves to the most significant bit, and the value allocated to each bit is moved upward, and as the value allocated to each bit moves upward, the remaining n bits of image data are different from the remaining bits. A bit expansion processing unit for allocating the calculated value according to the relationship of the fields; And
Dither processing unit that performs dithering on the image data received from the bit expansion processing unit
Display device comprising a. According to claim 3,
The dither processing unit,
Based on the position of the bit to which the dither value is applied, move the position downward for the value assigned to each bit up to the most significant digit, and assign 0 to the remaining upper bits as the value assigned to each bit moves downward. Characterized display device. According to claim 1,
The timing controller,
A bit expansion determining unit determining whether a mask comparison value calculated based on n-bit image data of the plurality of pixels to which the mask is applied is equal to or less than a predetermined threshold value;
When the mask comparison value is less than or equal to the threshold value according to the determination of the bit expansion determination unit, the number of bits of the image data of each of the plurality of pixels to which the mask is applied is extended by a predetermined number of bits to generate the k-bit image data. A bit extension processing unit; And
Dithering processing unit that performs dithering on each k-bit image data
Display device comprising a. The method of claim 5,
The bit expansion determination unit,
And calculating an average value of n-bit image data of the plurality of pixels to which the mask is applied as the mask comparison value, and determining whether the calculated mask comparison value is less than or equal to the threshold value. The method of claim 5,
The size of the mask has a predetermined fixed value, or the display device characterized in that it is determined based on the image data of the pixels to which the mask is applied. The method of claim 5,
The bit expansion processing unit,
A display device, characterized in that, for the k-bit image data, a value is assigned to an extended number of lower bits on the basis of the magnitude relationship of the image data values between adjacent pixels among the plurality of pixels. The method of claim 5,
The dither processing unit,
And dithering the extended image data based on values assigned to some lower bits of the k-bit image data and a plurality of dither patterns previously stored in a memory. The method of claim 5,
The dither processing unit,
A display characterized in that dithering is performed on the k-bit image data based on a value assigned to the lower bit of the bit expansion processing unit among the k-bit image data and a plurality of dither patterns previously stored in a memory. Device. According to claim 1,
The timing controller,
And controlling the number of bits to be extended for image data of each pixel to be different according to the gradation value of each of the plurality of pixels belonging to the partial region or the gradation value of the center pixel among the plurality of pixels belonging to the partial region. The method of claim 11,
The timing controller,
A display characterized by comparing the gradation value of the corresponding pixel with a predetermined reference gradation value, and controlling the gradation value of the corresponding pixel to be expanded to a greater number of bits than the number of extended bits when the gradation value of the corresponding pixel is lower than the reference gradation value. Device. According to claim 1,
The timing controller,
A bit expansion determining unit determining whether a mask comparison value calculated based on n-bit image data of the plurality of pixels to which the mask is applied is equal to or less than a predetermined threshold value;
When the mask comparison value is less than or equal to the threshold value according to the determination of the bit expansion determination unit, the number of bits of the image data of each of the plurality of pixels to which the mask is applied is extended by a predetermined number of bits to generate the k-bit image data. A bit extension processing unit;
A smoothing area determining unit determining whether at least some of the plurality of pixels to which the mask is applied form a smooth area when the mask comparison value exceeds the threshold value according to the determination of the bit expansion determining unit; And
Dithering processing unit that performs dithering on k-bit image data of each pixel or image data of pixels belonging to the smooth region determined by the smooth region determination unit
Display device comprising a. The method of claim 13,
The smooth area determining unit,
Among the plurality of pixels to which the mask is applied, a difference value between the image data of the center pixel and the image data of the pixels adjacent to the center pixel is calculated, and when the difference value is equal to or less than a preset smoothing reference value, the center pixel and the pixels adjacent to the center pixel are Display device characterized in that it is determined to belong to the smooth area. A data input step of receiving image data from outside;
A threshold value determining step of applying a mask and determining whether the mask comparison value calculated based on the image data of the plurality of pixels to which the mask is applied is equal to or less than a predetermined threshold value;
A data expansion step of expanding the number of bits of the image data of each of the plurality of pixels to which the mask is applied by a predetermined number of bits according to the determination result in the threshold determination step;
A dithering step of dithering the image data of each pixel expanded in the data expansion step; And
Data output step of outputting dithered image data
Method of driving a display device comprising a. The method of claim 15,
After the threshold determination step,
When the mask comparison value exceeds the threshold, a smooth area determination step of determining whether at least some of the plurality of pixels to which the mask is applied forms a smooth area, further comprising:
The dithering step is a method of driving a display device, characterized in that dithering is performed on image data of a plurality of pixels determined to be a smooth area in the smooth area determination step.

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