JP4503669B2 - Display device driving method, display device, and program thereof - Google Patents

Description

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

  Liquid crystal display devices that can be driven with relatively little power are widely used as display devices for stationary devices as well as portable devices. The liquid crystal display device has a slower response speed than a CRT (Cathode-Ray Tube) or the like, and the response is not completed in a rewrite time (16.7 msec) corresponding to a normal frame frequency (60 Hz) due to the transition gradation. For this reason, a method of driving by modulating the drive signal so as to emphasize the gradation transition from the previous time to the current time is also employed (see Patent Document 1 described later).

  For example, when the gradation transition from the previous frame FR (k-1) to the current frame FR (k) is rise driving, specifically, the current frame FR is emphasized so as to emphasize the gradation transition from the previous time to the current time. A voltage higher than the voltage level indicated by the video data D (i, j, k) in (k) is applied to the pixel.

As a result, when the gradation changes, the luminance level of the pixel is compared with the luminance level when the voltage level indicated by the video data D (i, j, k) of the current frame FR (k) is applied from the beginning. Thus, it increases more steeply and reaches the vicinity of the luminance level corresponding to the video data D (i, j, k) of the current frame FR (k) in a shorter period of time. Thereby, even when the response speed of the liquid crystal is slow, the response speed of the liquid crystal display device can be improved.
JP 2002-116743 A (publication date: April 19, 2002)

  However, in the above-described conventional configuration, when noise is mixed in the video signal, gradation transition caused by the noise is also emphasized, and a peaky video different from the original video may be output. On the other hand, if the degree to which gradation transition is emphasized is suppressed in order to prevent the display quality from being deteriorated due to the noise, the response speed of the pixel becomes slow.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a display device in which deterioration in display quality due to noise is prevented despite improvement in response speed of pixels. It is to be realized.

The driving method of a display device according to the reference of the present invention, in order to solve the above problems, so as to emphasize the grayscale transition to the current tone from the previous gradation, this gradation instructing to each pixel The display device driving method including the first correction step for correcting the correction includes a second correction step for suppressing high-frequency components in the spatial region of the gradation for each pixel corrected in the first correction step. It is characterized by.

The driving method of a display device according to the reference of the present invention, in order to solve the above problems, so as to emphasize the grayscale transition to the current tone from the previous gradation, this indicates to each pixel In the display device driving method including the first correction step for correcting the gradation, the second correction for cutting the peak in the spatial region by comparing the gradation to each pixel corrected in the first correction step. It is characterized by including a process.

  In these configurations, since the gradation transition from the previous gradation to the current gradation is emphasized in the first correction step, the response speed of the pixel can be improved. In addition to emphasizing the change in tone, in the next display, even if no noise is mixed, a gradation change due to the noise mixed in the previous time occurs.

  However, in the above configuration, since the high-frequency component in the spatial region is suppressed by the spatial low-pass filter processing and the peak cut processing by the second correction step performed after the first correction step, normal noise is not mixed. Both the improvement of the response speed of the pixel when displaying the video and the suppression of gradation change due to noise can be realized.

  Further, the high frequency component in the spatial region of the gradation to each pixel generated by noise is suppressed by the second correction step after the frequency becomes higher by the first correction step. Thus, since the high frequency component is suppressed after the difference between the spatial frequency of normal video and the spatial frequency of noise is enlarged, the second correction step is performed before the first correction step. In comparison, noise can be removed without hindering normal video display.

  As a result, it is possible to realize a display device in which the display quality is prevented from being deteriorated due to noise in spite of improving the response speed of the pixels.

In order to solve the above-described problem, the display device driving method according to the present invention corrects the gradation to be instructed to each pixel this time so as to emphasize the gradation transition from the previous gradation to the current gradation. In the driving method of the display device including the first correction step, the corrected gray levels of the first pixel group in the vicinity of the correction target pixel are averaged by using each pixel as the correction target pixel, and the first average value is obtained. to calculate, the difference between the first average value and the gradation after correction of the correction target pixel, and whether or not the determination process whether or exceeds a predetermined threshold, the threshold at the decision step On the basis of the determination result of whether or not the threshold value is exceeded, the corrected average gradation of the second pixel group in the vicinity of the characteristic pixel is averaged for the specific pixel that is determined to have a protruding gradation, and the second average The value is calculated, and the corrected gradation of the specific pixel is changed to the second average value. It is characterized in that it contains a second correction step.

  The second pixel group may be the same pixel group as the first pixel group, or may be a pixel group that is closer to the correction target pixel than the first pixel group. The first pixel group may be a pixel included in a rectangular area centered on a specific pixel, or a pixel included in a line segment centered on the specific pixel.

  Even in the above-described configuration, the high-frequency component in the spatial region of the gradation for each pixel corrected in the first correction step is suppressed by the second correction step performed after the first correction step. Therefore, in the same manner as the driving method of the display device described above, it is possible to realize a display device in which the display quality is prevented from being deteriorated due to noise even though the response speed of the pixels is improved.

  Further, in addition to the above configuration, the second pixel group may be a pixel group closer to the specific pixel than the first pixel group. In this configuration, it is determined whether or not the correction target pixel is a specific pixel based on the determination result with reference to the gradation of the first pixel group, and when the gradation needs to be changed, the specific pixel is more than the first pixel group. The gradation of the specific pixel is changed to the average value (second average value) of the gradation of the second pixel group close to. Therefore, even when the image is relatively high definition, the display quality of the display device can be improved without changing the gradation of the specific pixel to a gradation having no correlation with the surroundings.

  In addition to the above configuration, the first pixel group may be a pixel group including pixels included in a line segment centered on a specific pixel. In this configuration, since the gray level of the pixels included in the line segment is averaged to obtain the first average value, the gray level of the pixels included in the rectangular area is averaged to obtain the first average value. Compared to this, the amount of calculation can be reduced. Since noise is sudden, even if the first pixel group is a line segment, it is possible to suppress a decrease in display quality caused by noise as in the case of a rectangular region.

  On the other hand, instead of the above determination step, each pixel is a correction target pixel, a first pixel group consisting of pixels included in a line segment centered on the correction target pixel is specified, and among the first pixel group, The average value of the difference between the gradation of the pixel in one direction and the gradation of the correction target pixel when viewed from the correction target pixel, and the average value of the difference between the gradation of the pixel in the other direction and the gradation of the correction target pixel And a determination step of determining whether or not the signs of the two average values are different may be included.

  Even in this configuration, the second correction step performed after the first correction step suppresses the high-frequency component in the spatial region of the gradation for each pixel corrected in the first correction step. Therefore, in the same manner as the driving method of the display device described above, it is possible to realize a display device in which the display quality is prevented from being deteriorated due to noise even though the response speed of the pixels is improved.

  In addition to the above configuration, the second pixel group may be a pixel group that is shorter than the first pixel group and includes pixels included in a line segment centered on the correction target pixel.

  In this configuration, it is determined whether or not the correction target pixel is a specific pixel based on the determination result with reference to the gradation of the first pixel group, and when the gradation needs to be changed, the specific pixel is more than the first pixel group. The gradation of the specific pixel is changed to the average value (second average value) of the gradation of the second pixel group close to. Therefore, even when the image is relatively high definition, the display quality of the display device can be improved without changing the gradation of the specific pixel to a gradation having no correlation with the surroundings.

In the display device driving method according to the present invention, in addition to each of the above-described configurations, the determination step is repeated for each first pixel group including pixels included in line segments in different directions with the specific pixel as the center. The second correction step is characterized in that a pixel that is determined to have a protruding gradation based on a combination of determination results in each direction in the determination step is a specific pixel .

  In the configuration, since it is determined whether or not the gradation of the correction target pixel protrudes by a combination of determination results in a plurality of directions, more reliably than in the case of determining by a determination result in a single direction, Whether the pixel is a specific pixel can be identified. As a result, it is possible to more reliably suppress deterioration in display quality caused by noise.

In addition to the above-described configuration, the display device driving method according to the present invention may be configured such that the video signal input to the first correction unit is, for example, a video such as an MPEG (Moving Picture Expert Group) video. divided into a encoded video signal in each block, the length of the longitudinal direction of the first pixel group is characterized substantially the same der Rukoto the length of the block. In addition, when the video signal encoded by the block unit is enlarged and displayed, the block as the encoding unit is also enlarged, and accordingly, the length of the first pixel group in the longitudinal direction is also increased. Is set.

  In the above configuration, since the encoding unit (the size handled as an image as a single unit or the size in which noise is conspicuous because it is an encoding unit) and the length in the longitudinal direction of the first pixel group are substantially the same, It is possible to accurately determine whether the correction target pixel is a specific pixel. As a result, it is possible to more reliably suppress deterioration in display quality caused by noise.

The display device according to the reference of the present invention, in order to solve the above problems, so as to emphasize the grayscale transition to the current tone from the previous gradation, this time the tone for indicating to each pixel A display device having first correcting means for correcting includes a second correcting means for suppressing high-frequency components in the spatial region of the gradation to each pixel corrected by the first correcting means. .

In addition, in order to solve the above-described problem, the display device according to the embodiment of the present invention sets the gradation to be instructed to each pixel this time so as to emphasize the gradation transition from the previous gradation to the current gradation. The display device having the first correcting means for correcting includes second correcting means for comparing the gradations to the respective pixels corrected by the first correcting means and cutting the peak in the spatial region. It is characterized by.

In order to solve the above-described problem, the display device according to the present invention corrects the gradations that are designated to each pixel this time so as to emphasize the gradation transition from the previous gradation to the current gradation. In the display device having the correction means, each pixel is regarded as a correction target pixel, the corrected gray levels of the first pixel group in the vicinity of the correction target pixel are averaged, and a first average value is calculated. Determining means for determining whether or not a difference between the average value of 1 and the corrected gradation of the correction target pixel exceeds a predetermined threshold; and whether or not the threshold in the determining means is exceeded Based on the determination result, for the specific pixel for which the gradation is determined to protrude, the corrected gradation of the second pixel group in the vicinity of the characteristic pixel is averaged to calculate a second average value, Second correction means for changing the corrected gradation of the specific pixel to the second average value; It is characterized in that.

The pixel display device according to the reference of the present invention, in order to solve the above problems, instead of the determination means, as the correction target pixel of each of the pixels, included in the line segment centered on the correction target pixel The first pixel group consisting of the above is specified, and the average value of the difference between the gradation of the pixel in one direction and the gradation of the correction target pixel in the first pixel group as viewed from the correction target pixel is obtained, and the other direction An average value of the difference between the gray level of the pixel and the gray level of the correction target pixel is obtained, and determination means for determining whether or not the signs of the two average values are different is provided.

  The display device having the configuration drives the pixels by the above-described driving method of each display device. Therefore, similarly to each of the above-described driving methods, it is possible to realize a display device in which the display quality is prevented from being deteriorated due to noise although the response speed of the pixels is improved.

  Further, in addition to the above structure, the pixel may be a normally black mode and vertical alignment mode liquid crystal element. Here, when a normally black mode and vertical alignment mode liquid crystal element is used as a pixel, the response speed to decay gradation transition is slower than that of the rise, and it is driven by modulation so as to emphasize the gradation transition. However, in the gradation transition of the decay from the last time to the previous time, a difference is likely to occur between the actual gradation transition and the desired gradation transition. Therefore, when a transition from decay to rise occurs due to noise, the pixel gradation exceeds the desired gradation, and whitening occurs, which is easily recognized by the user. On the other hand, in the above configuration, gradation transition caused by noise is suppressed by the second correction unit disposed after the first correction unit. Therefore, although a normally black mode and vertical alignment mode liquid crystal element is used as a pixel, white light caused by noise can be prevented and display quality of the display device can be improved.

  Further, the program according to the present invention is a program for causing a computer to execute each step of the above-described display device driving method, and when the program is executed by the computer, the computer is used as the display device driving device. Operate. Therefore, similarly to each of the above-described driving methods, it is possible to realize a display device in which the display quality is prevented from being deteriorated due to noise although the response speed of the pixels is improved.

The driving method of a display device according to the reference of the present invention, as described above, so as to emphasize the grayscale transition to the current tone from the previous gradation, this time to correct the gradation instructing to each pixel The display device driving method including the first correction step includes a second correction step for suppressing a high-frequency component in the spatial region of the gradation for each pixel corrected in the first correction step.

The driving method of a display device according to the reference of the present invention, as described above, so as to emphasize the grayscale transition to the current tone from the previous gradation, this time to correct the gradation instructing to each pixel The display device driving method including the first correction step includes a second correction step of comparing the gray level to each pixel corrected in the first correction step and cutting a peak in the spatial region. It is a configuration.

  In the above configuration, the high frequency component in the spatial region of the gradation to each pixel generated by noise is suppressed by the second correction step after the frequency becomes higher by the first correction step. Noise can be removed without obstructing video display. As a result, there is an effect that it is possible to realize a display device in which the display quality is prevented from being deteriorated due to noise, although the response speed of the pixels is improved.

As described above, in the driving method of the display device according to the present invention, the first to correct the gradation to be instructed to each pixel this time so as to emphasize the gradation transition from the previous gradation to the current gradation. In the display device driving method including the correction step, each of the pixels is used as a correction target pixel, and the corrected gray levels of the first pixel group in the vicinity of the correction target pixel are averaged to calculate a first average value. , the difference between the first average value and the gradation after correction of the correction target pixel, a determination step of determining whether it exceeds a predetermined threshold, beyond the threshold value in the determination step Based on the determination result of whether or not there is a gradation, the second average value is calculated by averaging the corrected gradation of the second pixel group in the vicinity of the characteristic pixel for the specific pixel that is determined to have a protruding gradation. And a second correction step for changing the corrected gradation of the specific pixel to the second average value. Is a configuration that includes a.

  Even in the above-described configuration, the high-frequency component in the spatial region of the gradation for each pixel corrected in the first correction step is suppressed by the second correction step performed after the first correction step. Therefore, similarly to the above-described driving method of the display device, there is an effect that it is possible to realize a display device in which the display quality is prevented from being deteriorated due to noise, although the response speed of the pixels is improved.

As described above, in the driving method of the display device according to the reference of the present invention , in addition to the above configuration, the second pixel group is a pixel group closer to the specific pixel than the first pixel group. Therefore, even when the video is relatively high definition, the gradation of the specific pixel is not made to have no correlation with the surroundings, and the display quality of the display device can be improved.

In the driving method of the display device according to the reference of the present invention, as described above, in addition to the above-described configuration, the first pixel group is a pixel group including pixels included in a line segment centered on a specific pixel. In this configuration, since the gray level of the pixels included in the line segment is averaged to obtain the first average value, the gray level of the pixels included in the rectangular area is averaged to obtain the first average value. In comparison, the amount of calculation can be reduced.

In the display device driving method according to the reference of the present invention, instead of the determination step, each pixel is a correction target pixel, and the first pixel group including pixels included in a line segment centered on the correction target pixel is used. In the first pixel group, the average value of the difference between the gradation of the pixel in one direction and the gradation of the correction target pixel as viewed from the correction target pixel is obtained, and the gradation and correction of the pixel in the other direction are obtained. This is a configuration including a determination step of obtaining an average value of the difference from the gradation of the target pixel and determining whether the signs of the two average values are different.

  Even in this configuration, the second correction step performed after the first correction step suppresses the high-frequency component in the spatial region of the gradation for each pixel corrected in the first correction step. Therefore, similarly to the above-described driving method of the display device, there is an effect that it is possible to realize a display device in which the display quality is prevented from being deteriorated due to noise, although the response speed of the pixels is improved.

As described above, in the driving method of the display device according to the present invention , in addition to the above configuration, the second pixel group is shorter than the first pixel group and has a line segment centered on the correction target pixel. It is a pixel group which consists of pixels contained in.

  Therefore, even when the image is relatively high definition, the gradation of the specific pixel is not made to have no correlation with the surroundings, and the display quality of the display device can be improved.

  In the display device driving method according to the present invention, as described above, in addition to each of the above-described configurations, the determination step includes each of the first pixels including pixels included in line segments in different directions with the specific pixel as the center. It repeats about a pixel group, and the said 2nd correction process is the structure which makes the pixel judged that the gradation protruded by the combination of the determination result of each direction in the said determination process as a specific pixel.

  In the configuration, since it is determined whether or not the gradation of the correction target pixel protrudes by a combination of determination results in a plurality of directions, more reliably than in the case of determining by a determination result in a single direction, Whether the pixel is a specific pixel can be identified. As a result, there is an effect that it is possible to more reliably suppress deterioration in display quality caused by noise.

As described above, in the display device driving method according to the present invention, in addition to the above-described configuration, the video signal input to the first correction unit divides the video into a plurality of small blocks and codes each block. The length of the first pixel group in the longitudinal direction is substantially the same as the length of the block.

  In the above configuration, since the encoding unit (the size handled as an image as a single unit or the size in which noise is conspicuous because it is an encoding unit) and the length in the longitudinal direction of the first pixel group are substantially the same, It is possible to accurately determine whether the correction target pixel is a specific pixel. As a result, there is an effect that it is possible to more reliably suppress deterioration in display quality caused by noise.

As described above, the display device according to the reference of the present invention corrects the gradation to be instructed to each pixel this time so as to emphasize the gradation transition from the previous gradation to the current gradation. The display device having the means includes a second correction means for suppressing a high frequency component in a spatial region of the gradation to each pixel corrected by the first correction means.

As described above, the display device according to the reference of the present invention corrects the gradation to be instructed to each pixel this time so as to emphasize the gradation transition from the previous gradation to the current gradation. The display device having the means includes a second correction means for comparing the gradation to each pixel corrected by the first correction means and cutting a peak in the spatial region.

As described above, the display device according to the present invention includes the first correction unit that corrects the gradation to be instructed to each pixel this time so as to emphasize the gradation transition from the previous gradation to the current gradation. In the display device having each pixel, each of the pixels is used as a correction target pixel, the corrected gray levels of the first pixel group in the vicinity of the correction target pixel are averaged to calculate a first average value, and the first average the difference between the value and the gradation of the correction target pixel, a determination unit configured to determine whether it exceeds a predetermined threshold, based on whether the judgment result exceeds the threshold value in the determination means For the specific pixel for which the gradation is determined to be protruding, the corrected gradation of the second pixel group in the vicinity of the characteristic pixel is averaged to calculate a second average value, and the gradation of the specific pixel is calculated. And a second correction means for changing to the second average value.

As described above, the display device according to the reference of the present invention replaces the determination unit with each pixel as a correction target pixel, and is a first pixel including pixels included in a line segment centered on the correction target pixel. The group is specified, and the average value of the difference between the gradation of the pixel in one direction and the gradation of the correction target pixel in the first pixel group as viewed from the correction target pixel is obtained and the gradation of the pixel in the other direction And determining means for determining whether or not the signs of the two average values are different from each other.

  In these display devices, the pixels are driven by the driving method of each display device described above. Therefore, similarly to each of the above-described driving methods, there is an effect that it is possible to realize a display device in which the display quality is prevented from being deteriorated due to noise even though the response speed of the pixels is improved.

  As described above, in the display device according to the present invention, in addition to the above structure, the pixel is a normally black mode and vertical alignment mode liquid crystal element. Here, when a normally black mode and vertical alignment mode liquid crystal element is used as a pixel, the response speed to decay gradation transition is slower than that of the rise, and it is driven by modulation so as to emphasize the gradation transition. However, in the gradation transition of the decay from the last time to the previous time, a difference is likely to occur between the actual gradation transition and the desired gradation transition. Therefore, when a transition from decay to rise occurs due to noise, the pixel gradation exceeds the desired gradation, and whitening occurs, which is easily recognized by the user.

  On the other hand, in the above configuration, gradation transition caused by noise is suppressed by the second correction unit disposed after the first correction unit. Therefore, although the normally black mode and vertical alignment mode liquid crystal elements are used as pixels, it is possible to prevent the occurrence of white light due to noise and to improve the display quality of the display device.

  As described above, the program according to the present invention is a program that causes a computer to execute each step of the above-described display device driving method, and when the program is executed by the computer, the computer Operates as a driving device.

  Therefore, similarly to the above-described driving methods, there is an effect that it is possible to realize a display device in which the display quality is prevented from being deteriorated due to noise, although the response speed of the pixels is improved.

  An embodiment of the present invention will be described below with reference to FIGS. That is, the image display device (display device) 1 according to the present embodiment emphasizes the gradation transition from the previous time to the current time, thereby improving the response speed of the pixels, but displaying due to noise. This is an image display device 1 capable of preventing deterioration in quality.

  As shown in FIG. 2, the panel 11 of the image display device 1 includes a pixel array 2 having pixels PIX (1,1) to PIX (n, m) arranged in a matrix, and data signals of the pixel array 2. A data signal line driving circuit 3 for driving the lines SL1 to SLn and a scanning signal line driving circuit 4 for driving the scanning signal lines GL1 to GLm of the pixel array 2 are provided. In addition, the image display device 1 includes a control circuit 12 that supplies control signals to both the drive circuits 3 and 4, and the control circuit 12 that emphasizes the gradation transition based on the input video signal. A modulation drive processing unit 21 that modulates a video signal to be supplied is provided. These circuits are operated by supplying power from the power supply circuit 13.

  Hereinafter, before describing the detailed configuration of the modulation drive processing unit 21, the schematic configuration and operation of the entire image display device 1 will be described. For convenience of description, for example, only when the position needs to be specified as in the i-th data signal line SLi, it is not necessary to specify the position by referring to the position with a numeral or alphabetic character. When referring to the case or generically, the characters indicating the position are omitted for reference.

  The pixel array 2 includes a plurality (in this case, n) of data signal lines SL1 to SLn and a plurality (in this case, m) of scanning signal lines GL1 that intersect the data signal lines SL1 to SLn, respectively. GLm, and an arbitrary integer from 1 to n and an arbitrary integer from 1 to m are j, the pixel PIX (i, j, for each combination of the data signal line SLi and the scanning signal line GLj ) Is provided.

  In the present embodiment, each pixel PIX (i, j) includes two adjacent data signal lines SL (i-1) .SLi and two adjacent scanning signal lines GL (j-1) .GLj. It is arranged in the part surrounded by.

  As an example, the case where the image display device 1 is a liquid crystal display device will be described. As shown in FIG. 3, for example, the pixel PIX (i, j) has a gate as a switching element and a drain as a switching signal line GLj. A field effect transistor SW (i, j) connected to the data signal line SLi, and a pixel capacitor Cp (i, j) having one electrode connected to the source of the field effect transistor SW (i, j). ing. The other end of the pixel capacitor Cp (i, j) is connected to a common electrode line common to all the pixels PIX. The pixel capacitor Cp (i, j) includes a liquid crystal capacitor CL (i, j) and an auxiliary capacitor Cs (i, j) that is added as necessary.

  In the pixel PIX (i, j), when the scanning signal line GLj is selected, the field effect transistor SW (i, j) becomes conductive, and the voltage applied to the data signal line SLi becomes the pixel capacitance Cp (i, j). ) Is applied. On the other hand, while the selection period of the scanning signal line GLj ends and the field effect transistor SW (i, j) is cut off, the pixel capacitor Cp (i, j) continues to hold the voltage at the cut-off. Here, the transmittance or reflectance of the liquid crystal varies depending on the voltage applied to the liquid crystal capacitance CL (i, j). Therefore, if the scanning signal line GLj is selected and a voltage corresponding to the video data D to the pixel PIX (i, j) is applied to the data signal line SLi, the display state of the pixel PIX (i, j) is It can be changed in accordance with the video data D.

  The liquid crystal display device according to this embodiment is a vertical alignment mode liquid crystal cell as a liquid crystal cell, that is, when no voltage is applied, the liquid crystal molecules are aligned substantially perpendicular to the substrate, and the pixel PIX (i, x) A liquid crystal cell in which liquid crystal molecules are tilted from a vertical alignment state in accordance with the voltage applied to the liquid crystal capacitor CL (i, j) is adopted. The liquid crystal cell is normally black mode (when no voltage is applied, black display and Used).

  In the above configuration, the scanning signal line drive circuit 4 shown in FIG. 2 outputs a signal indicating whether or not the selected period, such as a voltage signal, to each of the scanning signal lines GL1 to GLm. Further, the scanning signal line drive circuit 4 changes the scanning signal line GLj that outputs a signal indicating the selection period based on a timing signal such as a clock signal GCK or a start pulse signal GSP given from the control circuit 12, for example. Yes. Thus, the scanning signal lines GL1 to GLm are sequentially selected at a predetermined timing.

  Further, the data signal line driving circuit 3 extracts the video data D... To the respective pixels PIX... Input in a time division manner as the video signal DAT by sampling at a predetermined timing. Further, the data signal line driving circuit 3 supplies each data signal line SL1 to each pixel PIX (1, j) to PIX (n, j) corresponding to the scanning signal line GLj selected by the scanning signal line driving circuit 4. An output signal corresponding to each video data D ... is output via SLn.

  The data signal line driving circuit 3 determines the sampling timing and the output timing of the output signal based on timing signals such as the clock signal SCK and the start pulse signal SSP input from the control circuit 12.

  On the other hand, each of the pixels PIX (1, j) to PIX (n, j) outputs to the data signal lines SL1 to SLn corresponding to itself while the scanning signal line GLj corresponding to the pixel PIX (1, j) to PIX (n, j) is selected. In accordance with the signal, the brightness and transmittance when emitting light are adjusted to determine its own brightness.

  Here, the scanning signal line driving circuit 4 sequentially selects the scanning signal lines GL1 to GLm. Therefore, all the pixels PIX (1,1) to PIX (n, m) of the pixel array 2 can be set to the brightness indicated by the video data D to each, and the image displayed on the pixel array 2 can be updated.

  In the image display device 1, the video signal DAT supplied from the video signal source S 0 to the modulation drive processing unit 21 may be transmitted in frame units (entire screen units), and one frame is divided into a plurality of fields. Although the data may be divided and transmitted in the field unit, the case where the data is transmitted in the field unit will be described below as an example.

  That is, in this embodiment, the video signal DAT supplied from the video signal source S0 to the modulation drive processing unit 21 is divided into a plurality of fields (for example, two fields) and transmitted in units of the field. .

  More specifically, when the video signal source S0 transmits the video signal DAT to the modulation drive processing unit 21 of the image display device 1 via the video signal line VL, after transmitting all the video data for a certain field, The video data for each field is transmitted in a time-sharing manner, for example, by transmitting video data for the next field.

  The field is composed of a plurality of horizontal lines. For example, in the video signal line VL, after all video data for a certain horizontal line is transmitted in a certain field, the horizontal line is transmitted next. For example, the video data for each horizontal line is transmitted in a time division manner.

  In this embodiment, one frame is composed of two fields, and in the even field, the video data of the horizontal line of the even-numbered row among the horizontal lines constituting one frame is transmitted. In the odd field, the video data of the horizontal line of the odd row is transmitted. Further, the video signal source S0 drives the video signal line VL in a time-sharing manner when transmitting video data for one horizontal line, and each video data is sequentially transmitted in a predetermined order.

  Here, as shown in FIG. 1, the modulation drive processing unit 21 according to the present embodiment includes a frame memory 31 that stores video data D (i, j, k) input from the input terminal T1 for one frame, Supplied to the video data D (i, j, k) of the current frame FR (k) input from the input terminal T1 and the same pixel PIX (i, j) as the video data D (i, j, k) Based on the video data D (i, j, k-1) of the previous frame FR (k-1) read out from the frame memory 31, the tone transition between the two should be emphasized. A modulation processing unit (first correction means) 32 that outputs corrected video data D2 (i, j, k) obtained by modulating the video data D (i, j, k) of the current frame FR (k); A spatial filtering process is performed on the corrected video signal DAT2 output from the modulation processing unit 32 to suppress high frequency components in the spatial domain. Spatial filtering section; and a (determining means second correction means) 33. Further, the video signal DAT3 output from the spatial filtering processing unit 33 is given to the control circuit 12 shown in FIG. 2, and the data signal line drive circuit 3 selects each pixel PIX (i, j) based on the corrected video signal DAT3. Drive.

  In the above configuration, when generating the video data D3 (i, j, k) for a certain pixel PIX (i, j), first, the modulation processing unit 32 first selects the video data D of the previous frame FR (k-1). The corrected video data D2 (i, j, k) is corrected by enhancing the gradation transition from (i, j, k-1) to the video data D (i, j, k) of the current frame FR (k). Is generated. Next, the spatial filtering processing unit 33 generates a video signal DAT3 by suppressing high-frequency components in the spatial domain in the corrected video signal DAT2 composed of the corrected video data D2 for each pixel PIX.

  Accordingly, in the portion of the corrected video signal DAT2 where the spatial frequency is sufficiently low, the corrected video data D2 (i, j, k) is output as it is as the video data D3 (i, j, k). In (i, j, k), the gradation transition from the previous time to the current time is emphasized. As a result, the pixel PIX (i, j) driven by the video data D3 (i, j, k) can respond at a sufficient speed.

  By the way, the video data D (i, j, k) is often continuous in time and space, whereas the noise is isolated in time and space. And has a higher spatial frequency component. Therefore, when noise is mixed in the video data D (i, j, k) input to the modulation drive processing unit 21, video from the video data D (i, j, k-1) of the previous frame FR (k-1). In many cases, the gradation transition of the data D (i, j, k) is larger than usual.

  Further, the modulation processing unit 32 emphasizes the gradation transition from the previous time to the current time. Therefore, a larger gradation transition appears in the corrected video data D2 (i, j, k) output from the modulation processing unit 32. On the other hand, normal video signals (video signals that do not contain noise) are often continuous in terms of time and space, and are generated by correcting video data D that does not contain noise. In the corrected video data D2, compared to the corrected video data D2 (i, j, k) mixed with noise, the gradation transition is not so emphasized. Therefore, in the corrected video signal DAT2, the gradation level of the corrected video data D2 (i, j, k) mixed with noise protrudes.

  However, in the present embodiment, a spatial filtering processing unit 33 is provided after the modulation processing unit 32. Therefore, in the corrected video signal DAT2, it is assumed that the gradation level of the corrected video data D2 (i, j, k) mixed with noise protrudes and the spatial frequency in the corrected video data D2 (i, j, k) is high. In addition, the high frequency component is suppressed by the spatial filtering processing unit 33. As a result, in the video signal DAT3 output from the spatial filtering processor 33, the degree to which the gradation level of the video data D3 (i, j, k) protrudes can be reduced.

  As a result, for a normal video signal DAT in which noise is not mixed, although the pixel PIX (i, j) can respond at a sufficiently high speed, gradation transition is not desired in a portion where noise is mixed. Emphasis can be prevented and the influence of noise can be removed from the displayed image. As a result, it is possible to realize an image display device that can prevent a momentary bright spot or complementary color point from being generated and can display a calm image although it can respond at high speed as a whole.

  Further, in the above configuration, since the spatial filtering processing unit 33 is provided in the subsequent stage of the modulation processing unit 32, the spatial processing unit 33 is based on the corrected video signal DAT2 after the gradation transition caused by noise is emphasized by the modulation processing unit 32. , Noise can be removed.

  More specifically, since the modulation processing unit 32 emphasizes the gradation transition, in the corrected video signal DAT2, the difference between the spatial frequency where noise is mixed and the spatial frequency where noise is not mixed. Is enlarged compared to the difference between both spatial frequencies in the video signal DAT. Therefore, compared with the configuration provided in the preceding stage of the modulation processing unit 32, the spatial filtering processing unit 33 according to the present embodiment reliably displays even when the difference between the two spatial frequencies in the video signal DAT is smaller. The influence of noise can be removed from the image.

  Hereinafter, as an example of a case where a filter that cuts the peak when the left and right corrected video data D2 is viewed as the spatial filtering processing unit 33 is employed, a configuration in which the spatial filtering processing unit 33 is removed or a preceding stage of the modulation processing unit 32 is used. The operation of the modulation drive processing unit 21 when noise is mixed will be described in comparison with the configuration provided in FIG.

  First, in a frame FR (k), FR (k + 1) and FR (k + 2) to a certain horizontal line L (j), video data D (*, j, k) shown in FIG. , D (*, j, k + 1) and D (*, j, k + 2) will be described as an example. 4 to 11, the horizontal axis indicates the position i on the horizontal line L (j) of the pixel PIX (i, j) corresponding to each video data, and the vertical axis indicates the level of each video data. Indicates the key level.

  In the example of FIG. 4, after video data D (*, j, k) having substantially the same gradation level is given in the frame FR (k), basically in the next frame FR (k + 1) , Video data D (i, j, k + 1) kept at a lower gradation level than the video data D (*, j, k) is given, and in the next frame FR (k + 2), Video data D (*, j, k + 2) maintained at a higher gradation level than the video data D (*, j, k) is given. However, in the frame FR (k + 1), noise is mixed in the video data D (p, j, k + 1) at the specific position (i = p) and should be substantially the same as other positions. The gradation level of the video data D (p, j, k + 1) is much lower.

  When the video data is input, the modulation processing unit 32 emphasizes the gradation transition from the previous frame to the current frame, so each frame FR (k), FR (k + 1) and FR (k + 2). , The corrected video data D2 (*, j, k), D2 (*, j, k + 1) and D2 (*, j, k + 2) shown in FIG. 5 are output.

  Here, the gradation transition of the corrected video signal DAT2 is emphasized by the modulation processing unit 32. Therefore, in the frame FR (k + 1), the gradation level of the corrected video data D2 (*, j, k + 1) is higher than the level of the video data D (*, j, k-1 + 1) before correction. Also lower. Also, the change in gradation level caused by noise, that is, the corrected video data D (p, j, k + 1) at a specific position and the corrected video data D2 (i, j, The level difference from k + 1) is larger than the level difference before correction.

  Further, although noise is not mixed in the frame FR (k + 2), noise is mixed in the video data D (p, j, k + 1) of the previous frame FR (k + 1). Therefore, the gradation level of the video data D (p, j, k + 2) of the frame FR (k + 2) is much higher than that of the corrected video data D2 (i, j, k + 2) at other positions. It is high. Further, due to the gradation transition, the level difference of the gradation level caused by noise is larger than the level difference before correction.

  As described above, in the corrected video signal DAT2, not only the frame FR (k + 1) in which noise is mixed but also the next frame FR (k + 2) has a change in gradation level due to the noise. The amount of change (level difference) is larger than the level difference of noise mixed in the video signal DAT. Therefore, as a comparative example, in the configuration in which the spatial video processing unit 33 is not provided and the corrected video signal DAT2 output from the modulation processing unit 32 is supplied to the control circuit 12, the image display device displays the noise due to noise mixed in the video signal DAT. The image has a longer period and a greater influence, and the display quality of the image display device is greatly deteriorated.

  Further, as described above, when noise is mixed in the frame FR (k + 1) having the video signal DAT, in the corrected video signal DAT2, the frame FR (k + 1) and the next frame FR ( In k + 2), level changes in different directions appear. Therefore, if the response speed is slow and the pixel PIX cannot reach the desired gradation level even if the gradation transition is emphasized, in the next frame FR (k + 2), from the previous frame FR (k). If the gradation transition is emphasized assuming that the gradation transition can be sufficiently performed to the previous frame FR (k + 1), the gradation transition cannot be emphasized appropriately, and the display quality of the image display apparatus may be deteriorated. .

  Specifically, as shown in FIG. 12, when the gradation transition from the previous time to the current time is decay → rise, the gradation transition from the previous time to the previous time is not sufficient as shown by the broken line in the figure, Even when the luminance level at the start of the frame FR (k + 1) has not been sufficiently lowered, the gradation has changed sufficiently in the current frame FR (k + 2) (indicated by a one-dot chain line in the figure). Similarly, when a pixel is driven, gradation transition is overemphasized and whitening occurs.

  In addition, as shown by the solid line in FIG. 13, when the gradation transition from the previous time to the current time is rise → decay, the gradation transition from the previous time to the previous time is not sufficient as shown by the broken line in the figure, Even when the luminance level at the start of the frame FR (k + 1) has not increased sufficiently, the current frame FR (k + 2) has undergone sufficient gradation transition (the dashed line in the figure). Similarly, when the pixel is driven, the gradation transition is overemphasized and black sink occurs.

  Therefore, when the corrected video signal DAT2 shown in FIG. 5 is given to the control circuit 12, the gradation transition of the pixel PIX (p, j) from the frame FR (k) to the frame FR (k + 2) is decayed to rise. For this reason, if the response speed of the pixel PIX (p, j) is not sufficient, the gradation transition of the pixel PIX (p, j) is overemphasized in the frame FR (k + 2), and whitening occurs. End up. FIG. 5 shows an example in which the video data D (i, j, k + 1) to the pixel PIX (p, j) is mixed with noise in the downward direction (in the direction of decreasing the gradation level). As described above, when noise in the upward direction (in the direction of increasing the gradation level) is mixed, there is a possibility of black sink.

  On the other hand, in the modulation drive processing unit 21 according to the present embodiment, a spatial filtering processing unit 33 is disposed after the modulation processing unit 32, and the spatial filtering processing unit 33 performs left and right correction on each corrected video data D2. By looking at the corrected video data D2 and cutting the peak, as shown in FIG. 6, the change in the corrected video data D2 (p, j, k + 1) is cut into the video data D3 (*, j, k + 1) is generated.

  Thereby, in the video signal DAT3 according to the present embodiment, the video data D3 (*, j, k + 1) in the frame FR (k + 1) is maintained at a substantially constant gradation level. Since the influence of noise is removed from the video signal DAT3 in the frame FR (k + 1), unlike the case of FIG. 5, the influence of noise does not appear in the frame FR (k + 2).

  As a result, in the video signal DAT, although the noise is mixed in the frame FR (k + 1), the gradation level change caused by the noise occurs in the image displayed by the image display device 1. Therefore, the display quality of the image display device 1 can be maintained at a high level.

  By the way, in the example shown in FIG. 4, in both the video signal DAT and the corrected video signal DAT2, the spatial frequency (1 pixel) where noise is mixed is higher than the spatial frequency where noise is not mixed. It is significantly higher. Therefore, the spatial filtering processing unit 33 is arranged before the modulation processing unit 32, and the video signal DAT5 after removing high-frequency components in the spatial region caused by noise from the video signal DAT is input to the modulation drive processing unit 21. Even in such a configuration, as shown in FIG. 7, the corrected video data D2 (*, j, k), D2 (*, j, k + 1) and D2 (*, j, The gradation transition caused by noise can be removed from k + 2).

  However, for example, as shown in FIG. 8, when noise causes a gradation transition including a relatively gentle gradation as compared with FIG. 4, the spatial filtering process is performed as shown in FIGS. 9 and 10. With the configuration in which the unit 33 is removed or the configuration in which the unit 33 is disposed before the modulation drive processing unit 21, it is difficult to remove the noise.

  Specifically, in the example of FIG. 8, the video data D (*, j, k) is maintained at a substantially constant level in the frame FR (k), but in the frame FR (k + 1), the noise is reduced. As a result of the mixing, the video data D (*, j, k + 1) has the video data D (p, j, k + 1) at the specific position (i = p) as a downward peak and the left region (i < In the region of p), the video data D (i, j, k + 1) decreases with a substantially constant gradient as i increases, and in the region on the right side (region of i> p), it is substantially constant. Increasing in the slope. Further, in the frame FR (k + 2), the video data D (*, j, k + 1) is converted into the video data D (p, j, k + 2) at the specific position (i = p) due to noise mixing. In the left region, the video data D (i, j, k + 1) increases with a substantially constant gradient in the left region, and the substantially constant gradient in the right region. It is decreasing in.

  When such a video signal DAT is input, the modulation processing unit 32 corrects the corrected video data D2 shown in FIG. 9 in each of the frames FR (k), FR (k + 1), and FR (k + 2). (*, j, k), D2 (*, j, k + 1) and D2 (*, j, k + 2) are output.

  Here, the gradation transition of the corrected video signal DAT2 is emphasized by the modulation processing unit 32. Therefore, in the frame FR (k + 1), the gradation level of the corrected video data D2 (*, j, k + 1) is higher than the level of the video data D (*, j, k-1 + 1) before correction. Also lower.

  Further, the modulation processing unit 32 tries to sharpen the peak of the spatial region of the video signal DAT by enhancing the gradation transition. However, in general, the gradation level of the corrected video data D2 is such that, for example, the degree to which gradation transition is emphasized is a circuit configuration of a driving circuit, a pixel driving method, or a range of gradation levels that can be expressed as a video signal. 9 is limited to a predetermined range, and FIG. 9 illustrates a case where the lower limit value of the gradation level of the corrected video data D2 is limited to TA as an example.

  Therefore, the modulation processing unit 32 cannot sufficiently sharpen the video signal DAT, and the corrected video data D2 (*, j, k + 1) is a region near the specific position (p1 <p < p2 region) is substantially the lower limit TA, and in the region on the left side of it, as i increases, it decreases with an approximately gradient with the video signal DAT, and in the region on the right side, it is substantially the same as the video signal DAT. Increase with a gradient of degree.

  Similarly, also in the frame FR (k + 2), the modulation processing unit 32 emphasizes the gradation transition and generates the corrected video signal DAT2. However, the example of FIG. 9 shows a case where the gradation level indicated by the corrected video signal DAT is near the lower limit value, and the modulation processing unit 32 may sufficiently sharpen the peak of the spatial region of the video signal DAT. it can. Therefore, the gradation level of the corrected video data D2 (*, j, k + 2) is higher than the level of the video data D (*, j, k-1 + 2) before correction and changes more steeply. To do. In particular, in the example of FIG. 9, as described above, the video data D (*, j, k) of the frame FR (k + 1) has a region near the specific position (i = p) in the spatial region. Since it changes so as to become the bottom, the video data D (*, j, k + 2) in the frame FR (k + 2) changes more steeply. As a result, in the configuration in which the corrected video signal DAT2 is supplied to the control circuit 12 as a comparative example, gradation transition due to noise is visually recognized in the region indicated by E in the figure.

  Here, in the example of FIG. 8, the spatial frequency of the noise mixed in the video signal DAT is lower than that in the case of FIG. 4, and the change in the gradation level due to the noise is a gradation. As described above, when the spatial frequency of the noise is close to the video signal DAT, as another comparative example, in the configuration in which the spatial filtering processing unit 33 is arranged before the modulation processing unit 32, the spatial filtering processing unit 33 is connected to the video signal. There is a possibility that noise cannot be removed from DAT. FIG. 10 shows a case where noise could not be removed. Similar to the case of FIG. 9, gradation transition due to noise is visually recognized.

  In particular, in the example of FIGS. 9 and 10, the gradation level of the corrected video data D2 (*, j, k + 2) is saturated to the lower limit value in the region near the specific position (region where p1 <p <p2). is doing. Therefore, when the signals shown in FIG. 9 and FIG. 10 are input and whitening occurs due to insufficient response speed as shown in FIG. 12, as shown in FIG. 14, the entire region near the specific position is spread over the entire region. The gradation level of each pixel PIX exceeds the gradation level indicated by the video data D, and white light is noticeable over the entire region.

  Here, if the spatial filtering processing unit 33 arranged in front of the modulation processing unit 32 performs a filtering process strong enough to remove noise, even if the noise can be removed, the normal video signal DAT has high frequency in the spatial domain. The component is removed, and the sharpness of the image may be impaired.

  On the other hand, since the spatial filtering processing unit 33 according to the present embodiment is arranged after the modulation processing unit 32, even when the spatial frequency of noise is close to the spatial frequency of the normal video signal DAT, After the difference between the two is enlarged by the modulation processing unit 32, the filtering process is performed. Therefore, even when the spatial filtering processing unit 33 is performing filtering processing with the same strength as in FIG. 10, as shown in FIG. 11, the video data D3 (*, j, k + 2) The change in the spatial region is more gradual than the video data D2 (*, j, k + 2) shown in FIG. Therefore, noise can be removed by a weaker filtering process than the comparative example provided in advance, and the occurrence of bright light over a wide range as shown in FIG. 14 can be prevented. As a result, compared with the comparative example, gradation transition caused by noise can be removed without impairing the sharpness of the image.

  Below, the structural example of the spatial filtering process part 33 is demonstrated. The first configuration example is a configuration that picks up what shows an abnormal value by skipping the average value of the area and returns it to the average value.

More specifically, when generating the video data D3 (i, j, k) of a certain pixel PIX (i, j), the spatial filtering processing unit 33 has a vertical 2a + 1 centered on the pixel PIX (i, j). A square area {(i−a, j−a) − (i + a, j + a)} of dots and horizontal 2a + 1 dots is set as a determination area. Further, when the gradation levels indicated by the video data D2 and D3 are denoted by the same reference numerals and the abnormality determination threshold value is C, the spatial filtering processing unit 33, as shown below,
abs (average (D2 (x, y, k) :( x = ia..i + a, y = ja..j + a))-D2 (i, j, k)) <C,
D3 (i, j, k) = D2 (i, j, k)
Set to
abs (average (D2 (x, y, k) :( x = ia..i + a, y = ja..j + a))-D2 (i, j, k))> = C,
D3 (i, j, k) = average (D2 (x, y, k) :( x = ia..i + a, y = ja..j + a))
Set to.

  In the above formula, abs and average are functions for calculating an average and an absolute value, respectively. A. . b represents a numerical range from a to b, and x: = a. . b indicates that x is repeated while changing from a to b. Therefore, average (D2 (x, y, k) :( x = ia..i + a, y = ja..j + a) is corrected video data D2 for all the pixels PIX included in the determination area. The average value of the gradation levels is shown.

  In the configuration described above, the spatial filtering processing unit 33 picks up the pixel PIX that shows an abnormal gradation by skipping the average value of the determination area around the pixel PIX, and returns the gradation level of the pixel PIX to the average value. Thus, the video data D3 for the pixel PIX is generated.

  Therefore, for example, when a video signal created with VGA (Video Graphics Array) resolution is displayed on a display with UXGA resolution, the original number of dots is small, and it is understood that there is little change in a specific area. It is particularly preferably used for a moving image.

  In the above example, since the original video signal is magnified by about 3 times, within the 3 × 3 dot area, the same gradation level is obtained, and the gradation level rarely protrudes at the dot level. is there. Therefore, a simple filter is particularly preferably used as in the above filtering process.

  The threshold C may be set as a constant, for example, a value of about 16 to 32 gradations as a gradation that can be visually recognized as an error, or a value (for example, an average value) according to the brightness of the determination area. May be set to 1/4).

  On the other hand, the second configuration example, like the first configuration example, picks up the average value of the determination area that shows an abnormal value by skipping, but unlike the first configuration example, The gradation of the picked-up pixel PIX is set to the average value of the neighboring area narrower than the determination area near the pixel PIX.

Specifically, as shown below, the spatial filtering processing unit 33
abs (average (D2 (x, y, k) :( x = ia..i + a, y = ja..j + a))-D2 (i, j, k)) <C,
D3 (i, j, k) = D2 (i, j, k)
Set to
abs (average (D2 (x, y, k) :( x = ia..i + a, y = ja..j + a))-D2 (i, j, k))> = C,
D3 (i, j, k) = average (D2 (x, y, k) :( x = ib..i + b, y = jb..j + b))
Set to. In addition, b is an integer smaller than a and is a square area {(ib, jb) − (i + b, 2b + 1 dots) and 2b + 1 dots (horizontal 2b + 1 dots) centering on the pixel PIX (i, j). j + b)} is the neighborhood area. Here, if b is set too large, the video signal may be blurred. Therefore, it is desirable to set b to about 1 dot. As will be described later, when the video signal is scaled and displayed (for example, when the original signal is enlarged and displayed), this value is also scaled (for example, the original signal). It is desirable to set it to a value enlarged at the same rate as the signal enlargement rate.

  In the above configuration example, the gradation of the picked-up pixel PIX is set to an average value in a neighboring area narrower than the determination area in the vicinity of the pixel PIX. Therefore, for example, as in the case where the edge of a bright object and a dark background is used as the determination area, there are not many pixels PIX near the average value of the determination area in the determination area, and the gradation distribution of the determination area is separated from each other. Even when a plurality of (for example, 2) gradations are collected, the spatial filtering processing unit 33 may output a gradation that has no correlation with the surroundings (a gradation that hardly exists in the determination area). Absent. As a result, the display quality of the image display device 1 can be improved.

  The third configuration example is a simplification of the pickup method in the first and second configuration examples, and includes a vertical line and a horizontal line centered on the pixel PIX (i, j). The pixel PIX that picks up an abnormal value by skipping the average value of at least one of them is picked up.

Specifically, as shown below, the spatial filtering processing unit 33
Condition 1 abs (average (D2 (i, y, k) :( y = ja..j + a))-D2 (i, j)) <C
Condition 2 abs (average (D2 (x, j, k) :( x = ia..i + a, k))-D2 (i, j)) <C
If both are satisfied,
D3 = D2 (i, j, k)
Set to, otherwise
D3 = average (D2 (x, y, k) :( x = ib..i + b, y = jb..j + b))
Set to.

Here, since the noise is abrupt, normally, it is possible to determine whether or not the noise is mixed by checking at least one of the vertical direction and the horizontal direction without comparison within the plane. Therefore, as in the first and second configuration example, with a smaller amount of calculation than when compared with the plane, you can pick up the pixel PIX that was contaminated by noise.

  In the above description, the determination is made based on whether the AND of condition 1 and condition 2 is true or false. However, the determination may be made based on the OR of both, or may be made based on only one of the two conditions.

  However, in the case of a video that often satisfies the above condition (1 or 2) even if no noise is mixed in one of the vertical and horizontal directions as in a relatively high-definition video, It is preferable to make a judgment based on whether the condition AND is true or false. On the other hand, if one of the two conditions is satisfied as in a relatively low-definition video, it is highly possible that the other condition is satisfied. The amount of calculation can be reduced by making a determination based on only one of the two conditions. Note that when a plurality of types of video can be input and an appropriate determination method differs depending on the type of video, the determination method may be switched according to the video.

  Further, in the above description, as in the second configuration example, the case where the gradation of the picked-up pixel PIX is set to the average value in the neighborhood area narrower than the determination area in the vicinity of the pixel PIX has been described as an example. However, like the first configuration example, the average value of the determination area may be set. However, as in the second embodiment, the display quality of the image display device 1 can be further improved by setting the average value in the neighborhood area.

  Furthermore, instead of the average value of the determination area or the neighboring area, the average value of the gradations of the pixels PIX included in the straight line of length 2a + 1 or 2b + 1 with the pixel PIX (i, j) as the center may be set. . The straight line may be either the vertical direction or the horizontal direction. However, when it is determined only by one of the above conditions 1 and 2, it is desirable to set the same direction as that direction.

  On the other hand, in the fourth configuration example, unlike the first to third configuration examples, the gradation of the video data D3 to the pixel PIX should be changed depending on whether or not the gradation level of the pixel PIX is a peak value. In this configuration, it is determined whether or not

As an example, the case of determining whether or not it is a peak value only in the horizontal direction will be described as an example. The spatial filtering processing unit 33, as shown below,
average (D2 (x, j, k) :( x = ia..i-1) -D2 (i, j, k))
* ((Average (D2 (x, j, k) :( x = i + 1..i + a) -D2 (i, j, k))) <0,
D3 = D2 (i, j, k)
Set to, otherwise
D3 = average (D2 (x, y, k) :( x = ic..i + c))
Set to. In the above equation, c is a constant set by the type of image, that is, the expected spatial frequency, and is, for example, an image that is expected to have a very high spatial frequency (extreme value in the above dot unit). C) is very small and about 1 or 2 is preferably used. On the other hand, for images expected to have a low spatial frequency (images accompanied by scale expansion), it is preferable to use about 3 to 5.

  In the above configuration, the right average value and the left average value of the pixel PIX (i, j) to be determined are compared to determine whether the gradation of the pixel PIX (i, j) to be determined is an extreme value. judge. Further, when the value is an extreme value, the average value of the left and right b dots to be determined is set as video data D3 (i, j, k).

  Thereby, the protruding gradation can be eliminated. Furthermore, even if it happens to be an extreme value in a normal video, or in the case of a normal video, generally, even if it is an extreme value, there is a certain degree of continuity. It ’s not an unnatural depression. As a result, the image display device 1 with good display quality can be realized.

  In the above description, it is determined whether or not the peak value is only in the horizontal direction, but it may be determined whether or not the peak value is in another direction such as the vertical direction. Even in this case, since the noise is generally sudden, the noise can be removed as described above. In addition, correction video data is obtained by combining peak value determinations in a plurality of directions and determinations compared with average values as in the first to third configuration examples, and whether these determinations are AND or OR. It may be determined whether or not D2 (i, j, k) should be changed. In this case, since the determination is made based on a plurality of conditions, it can be determined whether or not the corrected video data D2 (i, j, k) should be changed. In the above description, the video data D3 (i, j, k) is changed to the average value in the horizontal direction. However, the average value in the vertical direction may be used, or the average value in the area may be omitted. Similar effects can be obtained.

  In the above description, the case where the determination area is a square of (2a + 1) × (2a + 1) has been described as an example. However, the present invention is not limited to this. As described above, noise is generated independently of the scanning direction, and when it is determined that the noise is in one direction, it is often determined that the noise is also in another direction. Therefore, when the vertical and horizontal are (2 · a1 + 1) × (2 · a2 + 1), a rectangular area where a1 <a2 or a rectangular area where a1> a2 is satisfied may be used as the determination area. However, in the case of a square as in each of the above configuration examples, the determination accuracy does not depend on the direction, so that the determination can be made more accurately.

  On the other hand, when scanning in the horizontal direction, a line memory is required to compare the corrected video signal DAT2 in the vertical direction. Therefore, if simplification of the configuration is desired, it is better to set a1 <a2. desirable. In particular, when a1 = 1, there is no need to provide a line memory, so that the circuit configuration can be particularly simplified.

  Here, a2 can be set to an arbitrary value up to ½ of the width (n) of the display screen of the image display device 1, but if a2 is too small, the normal video signal DAT can be erroneously determined as noise. If it is too large, noise may not be removed. Therefore, the magnitude of a2 is set to a value selected according to the type of video signal DAT.

  For example, a general MPEG video is divided into a plurality of small blocks and encoded in units of blocks. Thus, in the case of video encoded in units of blocks, it is desirable to set a2 to a value substantially the same as the block size. For example, in the case of the above MPEG video, the block size is 8 × 8 to 16 × 16. Therefore, in this case, it is desirable to set a2 to about 4 to 8. In this way, by setting the length of the determination area in the longitudinal direction to be substantially the same as the encoding unit, the length of the determination area in the longitudinal direction can be set to a size that can be treated as a single image or encoded. Since it is a unit, it becomes a value corresponding to the size where noise is conspicuous, and noise can be removed accurately.

  In addition, for example, when an NTSC (National Television System Committee) video (640 × 480) is displayed on a display capable of displaying a high-vision (1920 × 1080; registered trademark), the video signal is scaled and displayed. First, the block size is enlarged or reduced by scale conversion. For example, in the above example, the block size is 24 × 24 to 48 × 48 because it is enlarged three times. Therefore, it is desirable that the length of the determination area in the longitudinal direction is also scaled in accordance with this and set to 24 to 48, that is, about a2 = 12 to 24.

  Note that the generation factor of the noise that affects the display is not limited to the original signal (for example, MPEG), and there is a possibility that the noise may be mixed due to system factors in the processes after the scale conversion. Here, if the area is expanded by scale conversion, the area of the noise itself is expanded. Therefore, it is desirable that the upper limit value is expanded in accordance with the scale conversion as described above as a suitable range. On the other hand, when the pixel size does not decrease as the resolution of the video signal increases, that is, when the spatial resolution is not improved as compared with the increase in the resolution of the video, smaller noise is easily noticeable. Therefore, in such a case, and when the noise mixed in the process after the scale conversion is expected to be relatively large due to system factors, the lower limit of the preferred range of the length in the longitudinal direction of the determination area The value may be set lower than the above value, for example, about 1/2, and the length of the determination area may be set to a value within the range (for example, about a2 = 6 to 24).

  In the above example, the case where the spatial filtering processing unit 33 suppresses the high-frequency component by cutting the peak in the spatial region of the corrected video signal DAT2 is exemplified. If the high frequency component is suppressed by attenuating a large frequency, the same effect can be obtained.

  Furthermore, in the above-described embodiment, the case where the liquid crystal cell of the vertical alignment mode and the normally black mode is used as a display element has been described as an example. However, the present invention is not limited to this. Even if the response speed is slow and the drive is modulated and emphasized so as to emphasize the gradation transition, the difference between the actual gradation transition and the desired gradation transition occurs in the gradation transition from the previous time to the previous time. If it is an element, the substantially same effect is acquired.

  However, the liquid crystal cell in the vertical alignment mode and normally black mode has a slower response speed with respect to the decay gradation transition than in the case of the rise, and even if it is driven by modulation so as to emphasize the gradation transition, In the decay gradation transition to the previous time, a difference between the actual gradation transition and the desired gradation transition is likely to occur, and whitening is likely to occur due to the decay → rise gradation transition caused by noise. Therefore, it is particularly effective to prevent gradation transition caused by noise by the configuration of the above embodiment.

  In the above embodiment, the case where each member constituting the modulation drive processing unit is realized only by hardware has been described as an example. However, the present invention is not limited to this. You may implement | achieve all or one part of each member with the combination of the program for implement | achieving the function mentioned above, and the hardware (computer) which performs the program. As an example, the computer connected to the image display device (1) may realize the modulation drive processing unit (21) as a device driver used when driving the image display device. In addition, when the modulation drive processing unit is realized as a conversion board built in or externally attached to the image display device, and the operation of the circuit realizing the modulation drive processing unit can be changed by rewriting a program such as firmware, By distributing the software and changing the operation of the circuit, the circuit may be operated as the modulation drive processing unit of the embodiment.

  In these cases, if hardware capable of executing the above-described functions is prepared, the modulation drive processing unit according to the embodiment can be realized only by causing the hardware to execute the program.

1, showing an embodiment of the present invention, is a block diagram illustrating a main configuration of a modulation drive processing unit of an image display device. FIG. It is a block diagram which shows the principal part structure of the said image display apparatus. It is a circuit diagram which shows the structural example of the pixel provided in the said image display apparatus. It is a graph which shows an example of the video signal inputted into the above-mentioned modulation drive processing part. FIG. 9 is a graph illustrating an operation of a comparative example, and is a graph illustrating an output of the modulation drive processing unit when the video signal is input to the modulation drive processing unit according to the comparative example. FIG. 10 is a graph illustrating the operation of the embodiment, and illustrating the output of the modulation drive processing unit when the video signal is input to the modulation drive processing unit according to the embodiment. FIG. 10 is a graph illustrating an operation of another comparative example, and is a graph illustrating an output of the modulation drive processing unit when the video signal is input to the modulation drive processing unit according to the comparative example. It is a graph which shows the other example of the video signal input into the said modulation drive process part. FIG. 11 is a graph illustrating the operation of the comparative example, and illustrating the output of the modulation drive processing unit when the video signal is input to the modulation drive processing unit according to the comparative example. FIG. 10 is a graph illustrating an operation of the other comparative example and showing an output of the modulation drive processing unit when the video signal is input to the modulation drive processing unit according to the comparative example. FIG. 10 is a graph illustrating the operation of the embodiment, and illustrating the output of the modulation drive processing unit when the video signal is input to the modulation drive processing unit according to the embodiment. It is a timing chart which shows an actual luminance level when the gradation transition from the last time to this time is from decay to rise. It is a timing chart which shows the actual luminance level when the gradation transition from the last time to this time is rise → decay. FIG. 10 is a graph showing the operation of each of the comparative examples, and is a graph showing the gradation level when the video signal is input to the modulation drive processing unit according to the comparative example.

1 Image display device (display device)
32 Modulation processing unit (first correction means)
33 Spatial filtering processing unit (determination means; second correction means)

Claims (4)

In the driving method of the display device including the first correction step of correcting the gradation instructed to each pixel this time so as to emphasize the gradation transition from the previous gradation to the current gradation,
Using each pixel as a correction target pixel, the corrected gradation of the first pixel group near the correction target pixel is averaged to calculate a first average value, and the first average value and the correction target pixel are calculated. A determination step of determining whether or not the difference from the corrected gradation exceeds a predetermined threshold;
Based on the determination result of whether or not the threshold value is exceeded in the determination step, a specific pixel that is determined to have a protruding gradation is a second pixel group in the vicinity of the specific pixel, the first pixel The corrected gradation of the second pixel group consisting of pixels equal to or less than the number of pixels of the group is averaged to calculate a second average value, and the corrected gradation of the specific pixel is changed to the second average value And a second correction step to
The video signal input to the first correction step is a video signal that is divided into a plurality of small blocks and encoded in units of blocks.
When the length in the longitudinal direction of the first pixel group is 2a + 1, a is a value that is ½ of the length of the block,
The determination step is repeated for each first pixel group consisting of pixels included in line segments in different directions centered on the correction target pixel,
The second correction step, the determination by the combination of the direction of the determination in step driving method of a display device, characterized in that the specific pixel a pixel is determined that gradation is protruded. In a display device having a first correction unit that corrects a gradation that is instructed to each pixel at this time so as to emphasize the gradation transition from the previous gradation to the current gradation,
Using each pixel as a correction target pixel, the corrected gradation of the first pixel group near the correction target pixel is averaged to calculate a first average value, and the first average value and the correction target pixel are calculated. Determining means for determining whether or not the difference from the corrected gradation exceeds a predetermined threshold;
Based on the determination result of whether or not the threshold value is exceeded by the determination means, the second pixel group in the vicinity of the specific pixel for the specific pixel determined to have a protruding gradation, the first pixel group The corrected gradation of the second pixel group consisting of pixels equal to or less than the number of pixels is averaged to calculate a second average value, and the corrected gradation of the specific pixel is changed to the second average value. Second correction means,
The video signal input to the first correction means is a video signal obtained by dividing the video into a plurality of small blocks and encoded in units of blocks.
When the length in the longitudinal direction of the first pixel group is 2a + 1, a is a value that is ½ of the length of the block,
The determination unit repeats the determination for each first pixel group including pixels included in line segments in different directions centered on the correction target pixel,
Said second correction means, said by the combination of the direction of the determination result of the determination means, a display device which is characterized in that the specific pixel a pixel is determined that gradation is protruded.   The display device according to claim 2, wherein the pixel is a normally black mode and vertical alignment mode liquid crystal element.   The program which makes a computer perform each process of Claim 1.

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