JP2012008203A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device that can conduct high resolution performance via a process for generating display data on each of the sub-pixels and displaying it, while improving deterioration in image quality by conducting an optimal image displaying process according to the characteristics of an input image signal.SOLUTION: A display device including a display panel in which a pixel is constituted by sub-pixels with four colors generates display data on each of the sub-pixels based on an input image signal and displays the data on the display panel. And, the sub-pixels with high brightness are disposed away from each other, whose areas are smaller than them of the other sub-pixels in a pixel. In the sub-pixels in four primary colors of RGBY, it is preferable to have a pixel arrangement 104 in which the sub-pixels are disposed so that G and Y with high brightness are away from each other, for example, in RGBY order, thereby conducting the process for improving the resolution. And the display device turns the process for improving the resolution OFF or ON according to the characteristics of an input image signal.

Description

  The present invention relates to a display device, and more particularly to a display device that supports multi-primary color display such as RGBY.

  2. Description of the Related Art Conventionally, various types of displays that form images with pixels have been commercialized as display means for displaying information and video. For example, one pixel is generally composed of sub-pixels (sub-pixels) of three primary colors composed of red (R), green (G), and blue (B), and thus color display is generally performed. Color filters are usually used to realize these subpixels. In such a color display technology, in recent years, it has been studied to expand color reproducibility in order to improve display quality.

  On the other hand, by increasing the number of primary colors to four or more primary colors using new colors other than the three primary colors of RGB, the area on the chromaticity diagram for chromatic colors is expanded or the luminance efficiency is improved. So-called multi-primary color displays have been developed. For example, an RGBY pixel configuration in which Y (yellow) is added to RGB and an RGBW pixel configuration in which W (white) is added to RGB are being studied.

  On the other hand, there is a sub-pixel sampling technique for sampling an input video signal in units of sub-pixels constituting a pixel in order to improve display resolution characteristics and perform high-definition video expression. In the subpixel sampling technique, for example, with respect to a pixel composed of three subpixels of RGB, each subpixel is regarded as one pixel, and the luminance is reproduced for each subpixel. Here, if RGB are arranged in the horizontal direction, sampling is performed by setting the horizontal sampling frequency to three times that of the conventional method. The subpixels are driven based on the signals corresponding to the sampled RGB subpixels.

  For example, Patent Document 1 discloses a technique for increasing the resolution of a rendered black-and-white text or graphics image and reducing the color edge. Here, a grayscale image is interleaved three times in the horizontal direction, and low-pass filtering is performed to create and display RGB image data.

JP 2001-117529 A

  When an input video signal is sampled and video representation is performed using digital data, a phenomenon in which video quality is deteriorated generally occurs in the process of processing a digital image. For example, in the frequency axis direction, interference fringes (beats) are generated due to a signal having a Nyquist frequency equal to or higher than ½ of the sampling frequency turning back to a low frequency. There is also a problem such as color misregistration (color aliasing) that occurs because the apparent RGB gradation is converted with respect to the input.

  These problems can be suppressed to some extent by setting a sampling frequency suitable for the quality of the input video and performing appropriate digital processing. However, sufficient video quality may not always be maintained due to factors such as pixel arrangement and sampling method. For example, when trying to improve the resolution characteristics by sub-pixel sampling on a general display that expresses the three primary colors of RGB as one pixel, for example, an image with a high spatial frequency such that white and black are alternately arranged When the is input, the degradation of video quality due to beats may be noticeable.

  In other words, it is possible to perform high-resolution expression by generating and displaying display data for each of the sub-pixels, but at this time, it is necessary to have a technical idea that does not cause deterioration in video quality. Become.

  Even when sub-pixel sampling is performed as described above, depending on the video-specific characteristics such as black and white video, OSD (On Screen Display), noisy video, and enhanced video, for example. Thus, not only the sub-pixel sampling is performed uniformly, but also the high-resolution processing can be executed with the optimal video quality by performing the optimal video display processing according to the characteristics of the input video signal.

  The present invention has been made in view of the above-described circumstances, and enables high-resolution expression by a process of generating and displaying display data for each of the sub-pixels. At this time, the optimum display is performed according to the characteristics of the input video signal. An object of the present invention is to provide a display device in which the deterioration of video quality is improved by performing video display processing.

  In order to solve the above problems, the first technical means of the present invention generates a display panel in which one pixel is constituted by four color sub-pixels and a video signal to be displayed on the display panel from an input video signal. In the display device having a display control unit that performs processing, the display control unit generates display data based on an input video signal for each of the sub-pixels, and displays the display data on the display panel. The process of improving the resolution of the display image and the process of generating display data based on the input video signal in units of pixels are switched, and the process of improving the resolution of the display image according to the characteristics of the input video signal is turned OFF or ON It is characterized by doing.

  According to a second technical means, in the first technical means, the display device includes a black and white video determination unit that determines whether or not the input video signal is a black and white video, and the display control unit includes the input video The determination result by the black and white video determination unit is used as a signal characteristic, and when at least the black and white video determination unit determines that the input video signal is a black and white video, the processing for improving the resolution is turned off. It is a feature.

  According to a third technical means, in the first or second technical means, the display device includes an OSD determination unit that determines whether an OSD signal is superimposed on an input video signal, and the display control unit includes: The presence / absence of superimposition of the OSD signal is used as the characteristic of the input video signal, and the resolution is improved when at least the OSD determination unit determines that the OSD signal is superimposed on the input video signal. This is characterized in that the processing to be performed is turned off.

  According to a fourth technical means, in any one of the first to third technical means, the display device includes a noise level determination unit that determines a noise level of an input video signal, and the display control unit The determination result by the noise level determination unit is used as the characteristics of the input video signal, and at least when the noise level determined by the noise level determination unit is higher than a predetermined level, the processing for improving the resolution is turned off. It is a feature.

  According to a fifth technical means, in any one of the first to fourth technical means, the display device includes an animation / CG determination unit that determines whether or not the input video signal is animation or computer graphics. And the display control unit uses a determination result by the animation / CG determination unit as a characteristic of the input video signal, and at least the animation / CG determination unit determines that the input video signal is an animation or a computer graphic. In such a case, the processing for improving the resolution is turned off.

  According to a sixth technical means, in any one of the first to fifth technical means, the display device includes an enhancement process determination unit that determines whether or not the enhancement process is performed on the input video. Then, the display control unit uses the presence / absence of enhancement processing by the enhancement processing unit as the characteristic of the input video signal, and it is determined that at least the enhancement processing unit performs enhancement processing on the input video signal. In this case, the processing for improving the resolution is turned off.

  According to a seventh technical means, in any one of the first to sixth technical means, the display device performs dot-by-dot display in which one pixel of the input video signal is displayed on one pixel of the display panel. A dot-by-dot determination unit that determines whether or not the image is displayed, and the display control unit uses at least whether or not the image is displayed by the dot-by-dot as a characteristic of the input video signal. When the dot-by-dot determination unit determines that the input video signal is displayed by dot-by-dot, the processing for improving the resolution is turned off.

  The eighth technical means is the technical means according to any one of the first to seventh technical means, wherein the display panel includes two high-intensity sub-pixels out of the four sub-pixels, and the other two low-color sub-pixels. The luminance is at least twice as high as the luminance of the luminance sub-pixel, and the high-luminance sub-pixels are arranged apart from each other in the one pixel.

  A ninth technical means is the eighth technical means, characterized in that the high-luminance sub-pixel and other sub-pixels other than the high-luminance sub-pixel are alternately arranged. .

  According to a tenth technical means, in the eighth or ninth technical means, the area of each of the high-luminance subpixels in the one pixel is made smaller than that of the other subpixels. Is.

  In an eleventh technical means according to any one of the eighth to tenth technical means, the four color sub-pixels are sub-pixels of four colors of red, green, blue, and yellow, and the high luminance It is characterized by having green and yellow sub-pixels as sub-pixels.

  According to the present invention, high-resolution expression is enabled by processing for generating and displaying display data for each of the sub-pixels. At this time, by performing optimal video display processing according to the characteristics of the input video signal, video quality is achieved. Can be provided.

It is the figure which showed typically the structural example of the display part of the liquid crystal display device which can apply this invention. 1 is a block diagram of a liquid crystal display device to which the present invention can be applied. FIG. 3 is a block diagram illustrating an example of a configuration of a video processing circuit illustrated in FIG. 2. It is a figure for demonstrating the resolution obtained according to the structure of a sub pixel. It is a figure for demonstrating pixel sampling and subpixel sampling.

  FIG. 1 is a diagram schematically showing a configuration example of a display unit of a liquid crystal display device to which the present invention can be applied, and shows a display unit 1 having a RGBY pixel configuration. Here, one pixel 11 has an RGBY pixel configuration. That is, each pixel of the color image displayed by the display unit 1 is R sub-pixel, G sub-pixel, B sub-pixel corresponding to R (red), G (green), B (blue), and Y (yellow), respectively. It consists of Y subpixels. Note that the arrangement order of the sub-pixels can be appropriately changed as long as an arrangement condition described later is satisfied, and may be an order such as YRGB.

  The same applies to the RGB pixel configuration and the RGBW pixel configuration. In the case of RGB, one pixel 11 is composed of RGB sub-pixels. In the case of RGBW, one pixel 11 is sub-RGBW sub-pixel. Consists of pixels.

FIG. 2 is a block diagram of a liquid crystal display device to which the present invention can be applied. This block diagram shows a video display control portion of the liquid crystal display device, which has a conventional pixel configuration in which one pixel is composed of RGB sub-pixels, a multi-primary pixel configuration such as RGBY, or RGBW. The present invention can also be applied to a pixel configuration.
The liquid crystal display device includes a display unit 1, an input unit 2, a video processing circuit 3, a control unit 4, a light source control circuit 5, and a drive control circuit 6. The display unit 1 includes an active matrix type color display panel, and the drive control circuit 6 generates a drive signal for driving the display unit 1.

  The input unit 2 is an interface for inputting a video signal such as a digital broadcast signal. The video processing circuit 3 executes various signal processes on the input video signal from the input unit 2.

  The control unit 4 includes a CPU and a memory that control the operation of the liquid crystal display device. The light source control circuit 5 adjusts the luminance of the backlight light source by controlling the power supplied to the backlight light source constituting the display unit 1 in accordance with a control command from the control unit 4.

  The display unit 1 includes a color filter 7, a liquid crystal panel body 8, and a backlight light source 9. The liquid crystal panel body 8 is formed with a plurality of data signal lines and a plurality of scanning signal lines intersecting therewith. The liquid crystal panel body 8 and the color filter 7 constitute a color liquid crystal panel including a plurality of pixel forming portions arranged in a matrix. The backlight light source 9 is a light source that illuminates the liquid crystal panel body 8.

  The display unit 1 having an RGBY pixel configuration will be described as an example. The drive control circuit 6 includes a display control circuit 61, a data signal line drive circuit 13, and a scanning signal line drive circuit 14. The display control circuit 61 corresponds to the display control unit of the present invention. The display control circuit 61 receives the data signal DAT (Ri, Gi, Bi) from the video processing circuit 3 and the timing control signal TS from a timing controller (not shown), and receives the digital video signal. DV (Ro, Go, Bo, Yo), data start pulse signal SSP, data clock signal SCK, latch slope signal LS, gate start pulse signal GSP, gate clock signal GCK, and the like are output.

  Each pixel 11 of the display unit 1 is composed of RGBY sub-pixels, and the data signal DAT is composed of three primary color signals (Ri, Gi, Bi) respectively corresponding to the three primary colors of red, green, and blue. The display control circuit 61 converts an input primary color signal (Ri, Gi, Bi) corresponding to the three primary colors of RGB into an output primary color signal (Ro, Go, Bo, Yo) corresponding to the four primary colors of RGBY. Is provided. The digital video signal DV is an output primary color signal (Ro, Go, Bo, Yo) output from the conversion circuit 62, and thereby displays a color image to be displayed on the display unit 1.

  The data start pulse signal SSP, the data clock signal SCK, the latch strobe signal LS, the gate start pulse signal GSP, the gate clock signal GCK, and the like are timing signals for controlling the timing for displaying an image on the display unit 1. It is.

  The data signal line drive circuit 13 receives the digital image signal DV (Ro, Go, Bo, Yo), the data start pulse signal SSP, the data clock signal SCK, and the latch strobe signal LS output from the display control circuit 61, and displays them. In order to charge the pixel capacitance in each sub-pixel of the unit 1, a data signal voltage is applied as a drive signal to the data signal line of each pixel.

Based on the gate start pulse signal GSP and the gate clock signal GCK output from the display control circuit 61, the scanning signal line driving circuit 14 activates an active scanning signal (a scanning signal for turning on the TFT) on the scanning signal line in the display unit 1. Voltage) is applied sequentially.
As a result, a voltage corresponding to the digital video signal DV is held in the pixel capacitance of each sub-pixel and applied to the liquid crystal layer. As a result, a color image represented by the digital video signal DV is displayed on the display unit 1 by RGBY color filters provided in each sub-pixel.

  The display control circuit 61 generates display data based on the input video signal for each of the sub-pixels, and displays the display data on the display unit 1 to improve the resolution of the display image, and the input video signal in units of pixels. It is possible to switch between processing for generating display data based on. That is, high resolution processing by subpixel sampling and conventional pixel sampling processing are switched and executed. The process is switched according to a predetermined characteristic of the video signal as will be described later.

FIG. 3 is a block diagram showing an example of the configuration of the video processing circuit 3 shown in FIG.
A video signal input from the input unit 2 to the video processing circuit 3 is subjected to video processing by an NR (noise reduction) unit 31, an IP conversion unit 32, a scaler unit 33, a contrast unit 34, and an enhancement unit 35. In the MIX unit 36, an OSD (On Screen display) signal is superimposed on the video signal subjected to the video processing, and is output to the display control circuit 61.

  The NR unit 31 performs noise reduction of the video signal, and is processed by a one-dimensional filter, a two-dimensional NR, a three-dimensional NR15, and the like. The IP converter 31 converts the input interlaced image into a progressive image. The scaler unit 33 performs resolution conversion on the IP-converted image data in accordance with the resolution of the display panel.

The contrast unit 34 adjusts the contrast of the video signal. When the contrast is increased, the bright part becomes brighter and the dark part becomes darker.
The enhancement unit 35 performs enhancement (contour emphasis) processing for correcting the edge portion transformed mainly in the scaling processing.

  The OSD signal is superimposed on the video signal output from the enhancement unit 35 by the MIX unit 36. The OSD signal is a signal indicating an image to be superimposed on the video displayed on the display panel. This image is generated as a menu image, an image showing a channel number, or the like when the main CPU receives an operation such as a menu screen display operation or a channel number display operation performed by the user on the remote controller or the main body operation unit. Read from. Further, as the OSD signal, a signal indicating an image generated on the apparatus side based on a signal indicating information related to video, such as an SI (Service Information) signal received together with the video signal, or a data broadcasting signal received separately. Is also included. The OSD signal includes, for example, a signal indicating an image such as program information, an electronic program guide, and data broadcasting. In addition, data broadcasting often includes character data corresponding to subtitles. In this case, a signal for displaying data broadcast video including subtitles also corresponds to an OSD signal.

  The video processing control unit 37 controls each unit that performs video processing. The video determination unit determines a predetermined characteristic of the video from the video signal output from the MIX unit 36. The predetermined characteristics are used to turn on / off the high resolution processing according to the present invention, and determine whether or not the video is a monochrome video, whether or not the OSD signal is superimposed, and the video Determining whether the signal is animation or CG (Computer Graphics), determining whether enhancement processing is being performed, determining whether the input video signal is displayed dot-by-dot on the display panel, determining the noise level, etc. I do.

For the determination of black and white video, genre information included as metadata in the digital broadcast signal is used. The genre information can be separated from the video signal after receiving the digital broadcast signal and input to the video determination unit 38. If metadata such as genre information is added to a video signal input from a device such as a DVD recorder, the information can be used.
Alternatively, it is determined by the image quality mode that a monochrome image is being displayed. In a television apparatus or the like, an image quality mode that can be set as a video display mode that can be set by a user is generally used. The image quality mode is a mode for optimizing the brightness and contrast of the screen so that the quality is suitable for the content viewed by the user.

  Examples of image quality modes include movie mode for optimally displaying movies, standard mode for displaying images with standard image quality, dynamic mode for displaying clear and vivid images, and optimal game images A game mode for displaying an image, a PC mode for optimally displaying an image output from the PC, an animation mode for optimally displaying an animation, and the like are set. For example, when a black and white display mode for displaying a black and white video such as a black and white movie is set, it is determined that the display video is a black and white video.

In order to determine the presence or absence of the OSD signal, the video processing control unit 37 or the OSD control unit (not shown) that generates and outputs the OSD signal causes the video determination unit 38 to send a signal informing the presence or absence of the OSD.
The determination of the presence / absence of animation and CG is also made based on this metadata if metadata such as genre information can be used. Further, the determination may be made according to an image quality mode such as an animation mode.

Further, as to whether or not the enhancement processing is being performed, the video determination unit 28 can acquire the control status of the enhancement unit 35 from the video processing control unit 37 and determine whether or not the enhancement processing is performed.
In addition, regarding the determination of whether or not the input video signal is displayed on the display panel in a dot-by-dot manner, the display device is provided with a dot-by-dot display mode similar to the image quality mode. It is determined whether or not dot-by-dot display is performed according to the mode setting for the control unit 37.

  In addition, the video determination unit 38 can determine the noise level of the video. For the determination of the noise level, a known technique can be used. For example, the gain of an automatic gain control (AGC) circuit provided in the demodulation circuit of the tuner, the C / N (Carrier to Noise ratio) acquired from the demodulation circuit ), Bit error rate (BER), or tuning state information during demodulation processing. Further, the noise level may be determined from the fluctuation value of the video data during the video blanking period. In the embodiment according to the present invention, it is determined whether or not the noise level is higher than a predetermined level. In this case, the value used for determining the noise level is compared with a predetermined threshold, and a value equal to or higher than the threshold is determined. If so, it can be determined that the noise level is high.

As described above, the video determination unit 38 determines whether the video is a black and white video, whether the OSD signal is superimposed, whether the video signal is animation or CG (Computer Graphics), and enhancement. It is used to determine whether processing is being performed, whether the input video signal is displayed dot-by-dot on the display panel, noise level, etc. This corresponds to the monochrome image determination unit, OSD determination unit, noise level determination unit, animation / CG determination unit, enhancement processing determination unit, and dot-by-dot display determination unit of the present invention.
Note that the video determination unit 38 is not limited to the configuration of performing video determination on the video output from the MIX unit 36, and appropriately performs determination processing at an optimal position. Further, it may be provided at dispersed positions according to the determination target. For example, the determination may be made based on a video signal input to the video processing circuit 3, or the video determination may be performed at an arbitrary place in the video processing circuit 36.

FIG. 4 is a diagram for explaining the resolution obtained according to the configuration of the sub-pixels. The horizontal axis of FIG. 4 shows the spatial frequency obtained by each subpixel configuration.
Here, a monochrome first pixel configuration 101, a second pixel configuration 102 with three RGB subpixels, a third pixel configuration 103 with RGBY subpixels, and a fourth pixel configuration 104 with RGBY subpixels. , Comparing. Here, the third pixel configuration 103 has a 1: 1: 1: 1 configuration in which the areas of the RGBY sub-pixels are the same. In the fourth pixel configuration 104, the area ratio of RGBY sub-pixels is R: B: G: Y = 1.6: 1.0: 1.6: 1.0.

For example, a full high-definition (HD) panel having a horizontal direction of 1920 pixels is assumed. Here, assuming 1 pixel / dot as a reference, in the case of the monochrome first pixel configuration 101, the spatial frequency indicating the pixel resolution is Fn. Here, in the full HD panel, 1920 pixels = 1920 dots, which has a resolution equivalent to 1 pixel.
In the case of the second pixel configuration 102 using RGB sub-pixels, since one pixel is composed of three sub-pixels having an equal area, the spatial frequency is 3 times 3Fn. In a full HD panel, 1920 pixels × 3 subpixels = 5760 dots, which is a resolution equivalent to 0.33 pixels.

  In the case of the third pixel configuration 103 using RGBY sub-pixels, one pixel is composed of four sub-pixels having an equal area, so that the spatial frequency is 4Fn, which is four times that of monochrome. . In a full HD panel, 1920 pixels × 4 subpixels = 7680 dots, which is a resolution equivalent to 0.25 pixels. Therefore, in the case of the third pixel configuration 103 of RGBY, the resolution is 1.33 times smaller than that of the second pixel configuration 102 of RGB.

Further, in the case of the fourth pixel configuration 104 with RGBY sub-pixels, one pixel has four ratios of R: G: B: Y = 1.6: 1.0: 1.6: 1.0. It consists of sub-pixels. Therefore, the spatial frequency of R and B having a ratio of 1.6 is Fn × 5.2 / 1.6 = 3.25Fn. The spatial frequency of G and Y having a ratio of 1.0 is Fn × 5.2 / 1.0 = 5.2Fn.
In a full HD panel, in the case of R and B sub-pixels, 1920 × 5.2 / 1.6 = 6240 dots, which is a resolution equivalent to 0.31 pixels. In the case of G and Y sub-pixels, 1920 pixels × 5.2 / 1.0 = 9984 dots, which is a resolution equivalent to 0.19 pixels. Accordingly, in the case of the R and B subpixels, the resolution is 1.08 times finer than that of the RGB second pixel configuration 102, and in the case of the G and Y subpixels having a small area, the RGB second pixel. The resolution is 1.73 times smaller than that of the configuration 102.

  In the embodiment according to the present invention, one picture element is composed of RGBY sub-pixels, and good pixel quality can be obtained by performing sub-pixel sampling. Here, in the embodiment according to the present invention, for example, it is important that one pixel is arranged in the order of RGBY. The reason is that among the RGBY, the G and Y sub-pixels having a high luminance ratio are arranged apart from each other. When the brightness of G and Y, which are high brightness, is sufficiently larger than the brightness of R and B, the brightness center becomes two by the high brightness sub-pixel that controls the brightness within one pixel, and the resolution is improved. Can do. In other words, by arranging in the order of RGBY, G and Y having a high luminance ratio from RGBY are arranged apart from each other without being adjacent to each other, thereby achieving the same effect as when the spatial resolution is increased, and video quality is achieved. Can be improved. Here, since the luminances of G and Y are high, the same effect can be obtained even with an arrangement of YRGB, GRYB, RYBG, or the like.

  Whether or not the luminance of the sub-pixel is sufficiently large is determined based on whether or not the luminance of the sub-pixel is twice or more that of the other sub-pixels. The reason for this is that G, which has a dominant luminance, has about five times the luminance of B and about two times the luminance of R in RGB configuration pixels. Here, it is said that the luminance is sufficiently large when the luminance of G and Y is at least twice that of R and B. That is, in the embodiment according to the present invention, two high-luminance sub-pixels out of four sub-pixels have at least twice the luminance of the other two low-luminance sub-pixels. It is necessary that high-luminance sub-pixels are arranged apart from each other in one pixel.

More specifically, in the configuration in which four subpixels are arranged, a subpixel having at least twice the luminance of the other subpixels is set as a high-luminance subpixel that is dominant in luminance. High luminance sub-pixels and other sub-pixels are alternately arranged. Thereby, in the configuration in which the pixels are continuously arranged, the high-luminance sub-pixels are alternately arranged, and the resolution is improved in the arrangement direction.
Further, even in the direction orthogonal to the subpixel arrangement direction, the resolution of the entire pixel matrix can be improved by alternately arranging the high-luminance subpixels and the other subpixels.

  The configuration in which the high-luminance subpixels and the other subpixels are alternately arranged is not limited to the RGBY arrangement. For example, it does not prevent the adoption of the RGBW arrangement or the RYBG arrangement.

Further, in the embodiment of the display device according to the present invention, the area of each of the high-intensity sub-pixels described above is made smaller than the other sub-pixels in one pixel. For example, the area ratio of RGBY in the pixel is R: G: B: Y = 1.6: 1.0: 1.6: 1.0.
As described above with reference to FIG. 3, in the case of the fourth pixel configuration 104 in which RGBY is arranged in an area ratio of 1.6: 1.0: 1.6: 1.0, 0 is set for R and B. It can be seen that a resolution equivalent to .31 pixels can be obtained, and for G and Y, a resolution equivalent to 0.19 pixels can be obtained. The apparent resolution can be improved by reducing the area ratio of the high-luminance sub-pixels. Therefore, in the embodiment according to the present invention, the area of the high-luminance subpixel that is dominant in luminance is made smaller than the areas of the other subpixels.

In other words, the sub-pixel sampling process for improving the resolution executable in the embodiment of the display device according to the present invention is basically as follows.
(1) In the display panel, one pixel is constituted by subpixels of four colors, and display data based on the input video signal is generated and displayed for each of the subpixels.
(2) Of the four color sub-pixels, two high-luminance sub-pixels have at least twice the luminance of the other two-color low-luminance sub-pixels, and within one pixel, High luminance sub-pixels are arranged apart.
(3) A high-luminance subpixel and other subpixels other than the high-luminance subpixel are alternately arranged in one pixel.
(4) Within each pixel, the area of each of the high-luminance sub-pixels is made smaller than that of the other sub-pixels.
(5) RGBY subpixels are used as the four-color subpixels, and the subpixels are arranged in the order of RGBY, YRGB, GRYB, RYBG, etc. within one pixel, with the high luminance subpixels being G and Y. Yes.
And with such a sub-pixel arrangement, processing of generating video data for each sub-pixel by sub-pixel sampling etc., and performing video representation, it is possible to express high resolution and improve degradation of video quality A display device can be provided.

5A and 5B are diagrams for explaining pixel sampling and sub-pixel sampling. FIG. 5A is a diagram for explaining the state of pixel sampling, and FIG. 5B is a diagram for explaining the state of sub-pixel sampling. . Here, the horizontal axis indicates the pixel position in the X direction, and the vertical direction indicates the pixel value.
In the pixel sampling shown in FIG. 5A, sampling is performed at one position for each pixel (pixel) with respect to an analog input video signal (input). For example, the input video signal is sampled at a position corresponding to RGB G of each pixel. If the pixel pitch at this time is Δx, the sampling frequency fs is fs = 1 / Δx. Then, the sampled pixel data is assigned to all of RGB and displayed. Accordingly, the RGB pixel value of each pixel is the same value. This technique is pixel sampling.

  In the case of pixel sampling, the R and B subpixels located on both sides of the G subpixel are spatially shifted by ± Δx / 3. Here, each of the input video signals corresponding to the sub-pixels has luminance and color. However, by performing pixel sampling, luminance components are dispersed and the spatial frequency characteristics are dull. In addition, color components are dispersed to cause color shift and distortion.

  In order to improve the dullness and distortion due to pixel sampling as described above, methods such as sub-pixel rendering have been devised. In subpixel rendering, a signal sampled by pixel sampling is interpolated between sampling points to create data of each subpixel, thereby spatially smoothing between the sampling points.

  The subpixel sampling shown in FIG. 5B does not create subpixel data by interpolating the data sampled in units of subpixels as described above, but actually samples the input video signal at subpixel intervals. Data can be obtained, and data faithful to the input video signal can be obtained. Here, the input video signal is sampled at a sampling frequency fx corresponding to a sub-pixel unit. In this case, the R subpixel is shifted by Δx / 3 from the G subpixel, and the B subpixel is sampled by shifting by −Δx from the G subpixel, and the pixel value is assigned.

  The processing according to the present invention for generating display data based on the input video signal for each of the subpixels can be applied to both the subpixel sampling processing and the subpixel rendering processing described above.

As a feature of the present invention, the processing for improving the resolution by subpixel sampling as described above is turned ON or OFF according to the characteristics of the input video signal displayed on the display device.
First, the process for improving the resolution is turned ON or OFF according to the determination result of whether or not the image is black and white. In the process of improving the resolution, the luminance is adjusted in units of subpixels in order to improve the luminance resolution. However, for example, in the case of an image with few color types and close to black and white, color adjustment on the screen may become conspicuous by adjusting the luminance in units of subpixels, and depending on the image, a large effect cannot be exhibited. In some cases. On the other hand, a large effect can be expected in the case of an image that contains many colors such as a natural image. Therefore, when the video determination unit 38 determines that the video signal is a black and white video, the display control circuit 61 turns off the process of improving the resolution by subpixel sampling and switches to the pixel sampling process.

  In addition, when the input video signal is an artificial video such as animation or CG, if the processing for improving the resolution is performed, coloring may be conspicuous and a sufficient effect may not be obtained. For example, in a simplified image such as a punch picture in CG, coloring may be conspicuous because it is a simple image. Therefore, when the video determination unit 38 determines that the video signal is animation or CG, the display control circuit 61 turns off the process of improving the resolution by subpixel sampling and switches to the pixel sampling process.

  Further, when the OSD signal is superimposed on the input video signal, for example, the EPG (electronic program guide), the menu screen, and the like need not inherently improve the resolution. In addition, due to the processing for improving the resolution, coloring may occur at the edge portion of the image. Accordingly, when the video determination unit 38 determines that the OSD signal is superimposed on the input video signal, the display control circuit 61 turns off the processing for improving the resolution by subpixel sampling, and performs pixel sampling processing. Switch to.

  Similarly, when an input video signal created by a PC or the like is displayed dot-by-dot, the input video signal pixel and the display panel pixel have a one-to-one relationship, and mainly display characters and figures. Therefore, adverse effects such as coloring are more conspicuous than the effect of improving the resolution. Therefore, when the video determination unit 38 determines that the video signal is to be displayed dot-by-dot, the display control circuit 61 turns off the processing for improving the resolution by sub-pixel sampling and switches to pixel sampling processing. .

  Further, when enhancement processing is performed on the video signal, processing for improving the resolution is turned off. In enhancement processing, edge enhancement is performed on a pixel basis. The processing for improving the resolution according to the present invention can be said to be edge enhancement in units of subpixels, and in any case, the processing is the same in the sense that the high frequency portion of the video is enhanced. For this reason, when enhancement processing is performed, processing for further improving the resolution is performed on the image emphasized by enhancement processing, resulting in strong coloration and image quality degradation. Therefore, when the video determination unit 38 determines that the enhancement processing is performed on the input video signal, the display control circuit 61 turns off the processing for improving the resolution by subpixel sampling, and performs the pixel sampling processing. Switch to.

  Also, when the input video signal has a lot of noise, the processing for improving the resolution is turned off. Of the noise that enters the video signal, the noise in the weak electric field of the broadcast wave often includes a high-frequency component and is white and is called snow noise. When the processing for improving the resolution according to the present invention is applied to such a video signal with a lot of snow noise, the white noise is inherently colored, and the difference from the white noise is conspicuous, and the video quality is lowered Resulting in. Therefore, when the video determination unit 38 determines that the noise level of the input video signal is higher than a predetermined level, the display control circuit 61 turns off the process for improving the resolution by subpixel sampling and switches to the pixel sampling process.

  In the present embodiment, the processing for improving the resolution is performed for the display image having the specific characteristics as described above, and the processing for improving the resolution is turned on for the display image determined not to have the specific characteristics. . When the process for improving the resolution is ON, the display process by subpixel sampling as described above is performed. When the process for improving the resolution is OFF, the process is switched to pixel sampling.

  Thus, in the embodiment according to the present invention, the processing for improving the resolution of the display image is turned ON / OFF according to the characteristics of the input video signal. In particular, when the input video signal is a monochrome video, when the OSD signal is superimposed, when the noise level is higher than a predetermined level, when the input video signal is animation or CG, enhancement processing is performed on the input video signal. If the input video signal is displayed in a dot-by-dot manner, the process for improving the resolution is turned off in other cases, and otherwise it is turned on. In addition, the processing for improving the resolution may be turned off only for one or more of the above characteristics.

  In the embodiment according to the present invention, the display data is generated and displayed for each of the sub-pixels to enable high-resolution expression, and at this time, the high-resolution expression process is turned on according to the characteristics of the input video signal. -By turning it OFF, it becomes possible to perform video display with optimal video quality according to the input video signal.

DESCRIPTION OF SYMBOLS 2 ... Input part, 3 ... Video processing circuit, 4 ... Control part, 5 ... Light source control circuit, 6 ... Drive control circuit, 7 ... Color filter, 8 ... Liquid crystal panel main body, 9 ... Backlight light source, 11 ... Pixel, 13 Data signal line drive circuit, 14 Scanning signal line drive circuit, 15 Dimension NR, 28 Image determination unit, 31 IP conversion unit, 31 NR unit, 32 IP conversion unit, 33 Scaler unit, 34 Contrast part 35 ... Enhancement part 36 ... MIX part 36 ... Video processing circuit 37 ... Video processing control part 38 ... Video determination part 61 ... Display control circuit 62 ... Conversion circuit 101 ... Pixel configuration 102 ... Pixel configuration, 103... Pixel configuration, 104.

In order to solve the above problems, the first technical means of the present invention generates a display panel in which one pixel is constituted by four color sub-pixels and a video signal to be displayed on the display panel from an input video signal. A display control unit that performs processing, wherein the display control unit samples the input video signal at sub-pixel intervals to generate display data based on the input video signal for each of the sub-pixels. Processing for improving the resolution of a display image by displaying data on the display panel, sampling at one position for each pixel, and assigning the sampled data for each pixel to other subpixels in the same pixel by switching between processing for generating display data based on the input image signal in pixels by There is obtained by characterized in that the display OFF or ON the processing for improving the resolution of the image according to the characteristics of the input video signal.

In a sixth technical means, in any one of the first to fifth technical means, the display device determines whether enhancement processing for performing edge enhancement of an image is performed on the input video. An enhancement processing determination unit, wherein the display control unit uses presence / absence of enhancement processing by the enhancement processing determination unit as a characteristic of the input video signal, and at least the enhancement processing determination unit performs enhancement processing on the input video signal. If it is determined that the process is being performed, the process for improving the resolution is turned off.

The subpixel sampling shown in FIG. 5B does not create subpixel data by interpolating the data sampled in units of subpixels as described above, but actually samples the input video signal at subpixel intervals. Data can be obtained, and data faithful to the input video signal can be obtained. Here, the input video signal is sampled at a sampling frequency fx corresponding to a sub-pixel unit. In this case, the R subpixel is shifted by Δx / 3 from the G subpixel, and the B subpixel is sampled by shifting by −Δx / 3 from the G subpixel, and the pixel value is assigned.

Claims (11)

In a display device having a display panel in which one pixel is configured by sub-pixels of four colors, and a display control unit that performs processing for generating a video signal to be displayed on the display panel from an input video signal,
The display control unit generates display data based on an input video signal for each of the sub-pixels, and displays the display data on the display panel to improve the resolution of a display image, and input video in units of pixels. A display device characterized in that a process for generating display data based on a signal is switched, and a process for improving the resolution of the display image is turned OFF or ON in accordance with characteristics of an input video signal.   2. The display device according to claim 1, wherein the display device includes a black and white video determination unit that determines whether or not the input video signal is a black and white video, and the display control unit is configured as a characteristic of the input video signal. The display is characterized in that the determination result by the black and white video determination unit is used, and at least when the input video signal is determined to be a black and white video by the black and white video determination unit, the processing for improving the resolution is turned off. apparatus.   3. The display device according to claim 1, wherein the display device includes an OSD determination unit that determines whether an OSD signal is superimposed on an input video signal, and the display control unit includes the input video signal. If the OSD determination unit determines that the OSD signal is superimposed on at least the input video signal, the processing for improving the resolution is turned off. A display device characterized by:   4. The display device according to claim 1, wherein the display device includes a noise level determination unit that determines a noise level of the input video signal, and the display control unit is characterized by the characteristics of the input video signal. As a display device, the determination result by the noise level determination unit is used, and at least when the noise level determined by the noise level determination unit is higher than a predetermined level, the processing for improving the resolution is turned off. .   5. The display device according to claim 1, wherein the display device includes an animation / CG determination unit that determines whether the input video signal is animation or computer graphics, and the display The control unit uses a determination result by the animation / CG determination unit as a characteristic of the input video signal, and if the input video signal is determined to be animation or computer graphic by at least the animation / CG determination unit, A display device characterized by turning off processing for improving resolution.   The display device according to claim 1, wherein the display device includes an enhancement process determination unit that determines whether an enhancement process is performed on the input video, and the display control. The presence / absence of enhancement processing by the enhancement processing unit as the characteristics of the input video signal, and if the enhancement processing unit determines that the input video signal is enhanced at least, the resolution is A display device characterized by turning off processing to be improved.   The display device according to claim 1, wherein the display device performs dot-by-dot display that displays one pixel of the input video signal on one pixel of the display panel. A dot-by-dot determination unit that determines whether the image is a video displayed by the dot-by-dot as a characteristic of the input video signal, and at least the dot-by-dot determination unit When the input video signal is determined to be displayed by dot-by-dot, the display device is configured to turn off the processing for improving the resolution.   8. The display device according to claim 1, wherein the display panel includes two high-luminance sub-pixels out of the four sub-pixels, and the other two low-luminance sub-pixels. A display device having a luminance at least twice as high as the luminance, wherein the high-luminance sub-pixels are arranged apart from each other in the one pixel.   9. The display device according to claim 8, wherein the high-luminance sub-pixels and other sub-pixels other than the high-luminance sub-pixels are alternately arranged.   10. The display device according to claim 8, wherein an area of each of the high-luminance sub-pixels is smaller than that of the other sub-pixels in the one pixel.   11. The display device according to claim 8, wherein the four-color sub-pixels are four-color sub-pixels of red, green, blue, and yellow, and the high-luminance sub-pixels are green and green. A display device having yellow sub-pixels.

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