JP2008032766A - Display device, display control circuit and control method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display control circuit that can eliminate or decrease a roughness appearance of a still image by a simple configuration. <P>SOLUTION: The display control circuit 200 of a display device of the present invention functions as follows: a high frequency matrix having a large spatial frequency component in a high-frequency region stored in a matrix memory section 21 is multiplied with a predetermined value by a volume section 21; the high frequency matrix including the above multiplied value is added to a given display gradation data by a high frequency adding section 23; the compensated display gradation data are stored in an output data memory section 26; and the data are outputted as a digital image signal to a source driver according to a control signal CT of a timing control section 24. As an image displayed in a display section driven by the source driver has a large spatial frequency component in a high-frequency region, a local roughness appearance is hardly visible and a roughness appearance of a display screen as a whole can be eliminated or decreased. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an active matrix display device such as a liquid crystal display device using a switching element such as a thin film transistor, and a display control circuit thereof.

  In general, an active matrix liquid crystal display device includes a display unit including two substrates sandwiching a liquid crystal layer, and one of the two substrates has a plurality of data as video signal lines. Lines and a plurality of gate lines as scanning signal lines are arranged in a lattice pattern, and a plurality of pixel formation portions are provided that are arranged in a matrix corresponding to the intersections of the plurality of data lines and the gate lines. Yes. Each pixel formation portion constitutes a display portion of the device. A TFT (Thin Film Transistor) which is a switching element in which a gate terminal is connected to a gate line and a source terminal is connected to a data line, and the TFT And a pixel electrode connected to the drain terminal. The substrate including these pixel formation portions is called a TFT substrate. The other substrate facing the TFT substrate out of the two substrates has a common electrode which is a common electrode provided in common for the plurality of pixel forming portions, and a color filter for forming a display color. (CF: Color Filter). This substrate is called a CF substrate.

  Such an active matrix liquid crystal display device includes a data driver for driving the data line of the display portion, a gate driver for driving the gate line of the display portion, and a common electrode driving circuit for driving the common electrode, , A data driver, a gate driver, and a display control circuit for controlling the common electrode driving circuit.

  In recent years, active matrix liquid crystal display devices have been widely used as display devices for portable devices such as mobile phones and PDAs, and as large display devices such as televisions, and higher-definition and high-quality displays are required. The

For example, a matrix having a speed-dependent high-frequency spatial frequency emphasis filter circuit that emphasizes the motion component of a display image according to its speed in order to eliminate blurring when displaying a moving image and perform high-quality display. There is a type video display device (see Patent Document 1). By applying the video signal to the filter circuit, enhancement that compensates for the low-pass effect depending on the speed is performed, and as a result, high-quality display in which the blur of the moving image is eliminated can be performed.
JP 7-199856 A

  However, although the above conventional matrix type video display device can eliminate the blur of the moving image, it cannot display a high-quality still image. In particular, in an active matrix display device, there may be variations in the display characteristics of the pixel formation portion due to variations in characteristics of TFTs used as switching elements and irregularities in the liquid crystal layer. A still image may be displayed. Such a feeling of roughness of the still image deteriorates the display quality of the matrix type video display device.

  In this regard, in an active matrix display device, it may be possible to form a TFT or the like so that the display characteristics of the pixel formation portion hardly vary, but even in that case, the manufacturing cost is very high. It is not practical.

  Further, although not a speed-dependent high-frequency spatial frequency emphasizing filter circuit like the conventional matrix type video display device, a filter circuit for emphasizing a general high-frequency spatial frequency is provided, and a video signal is given to this circuit. Thus, a matrix type display device that eliminates the roughness of still images can be considered. When the spatial frequency in the high frequency range is emphasized in this way, the rough feeling of the still image may be eliminated or reduced. However, since the above-described filter circuit needs to perform advanced calculations at high speed, the configuration thereof becomes complicated, and the manufacturing cost of the device increases.

  In view of the above, an object of the present invention is to provide a display control circuit that can eliminate or reduce the roughness of a still image with a simple configuration, and an active matrix display device including the display control circuit.

According to a first aspect of the present invention, an image signal composed of a plurality of display gradation data for displaying a plurality of pixels constituting a display image at a predetermined gradation is received from the outside, and roughness is caused when the display image is displayed. A display control circuit for outputting an image signal compensated to be suppressed,
A plurality of correction gradation data arranged to form a matrix for performing the compensation, and the spatial frequency component of the matrix when the matrix is handled as an image by associating with the plurality of display gradation data A matrix storage unit for storing the plurality of corrected gradation data set such that a high frequency spatial frequency component in a displayable spatial frequency region is larger than a low frequency spatial frequency component;
Matrix addition for outputting the compensated image signal including display gradation data obtained by adding a plurality of correction gradation data stored in the matrix storage unit to the corresponding display gradation data, respectively. A part.

According to a second invention, in the first invention,
The matrix storage unit performs correction in which the number of correction gradation data arranged in the vertical direction of the matrix is less than half of the number of pixels arranged in the vertical direction of the display image and arranged in the horizontal direction of the matrix. Storing the plurality of corrected gradation data set so that the number of gradation data is less than or equal to half the number of pixels arranged in the horizontal direction of the display image;
The matrix adding unit adds a plurality of correction gradation data stored in the matrix storage unit to the plurality of display gradation data selected so that corresponding ranges do not overlap each other. The compensated image signal including tone data is output.

According to a third invention, in the first invention,
The matrix storage unit stores the plurality of correction gradation data arranged to form a plurality of matrices corresponding to colors displayed in the plurality of pixels;
The matrix adding unit includes display gradation data obtained by adding the plurality of correction gradation data stored in the matrix storage unit to the plurality of display gradation data for each corresponding color. The compensated image signal is output.

According to a fourth invention, in the third invention,
The matrix adding unit includes:
A volume unit for multiplying the plurality of corrected gradation data stored in the matrix storage unit by a coefficient stored in advance for each corresponding color;
The compensated image signal including display gradation data obtained by adding the plurality of corrected gradation data multiplied by the volume unit to the plurality of display gradation data for each corresponding color is output. And a high-frequency adding section.

A fifth invention is the fourth invention,
The volume unit stores the plurality of coefficients including a coefficient having a value of 0.

A sixth invention includes a plurality of video signal lines for transmitting a plurality of video signals corresponding to the image signals output from the display control circuit according to any one of the first to fifth inventions,
A plurality of scanning signal lines intersecting with the plurality of video signal lines;
The plurality of video signal lines and the plurality of scanning signal lines are arranged in a matrix corresponding to the intersections of the plurality of scanning signal lines, respectively, and are in a conductive state or in accordance with signals applied to the scanning signal lines passing through the corresponding intersections. A plurality of pixel forming portions each including a switching element to be cut off;
An active matrix display device comprising a drive control circuit for driving the plurality of video signal lines and the plurality of scanning signal lines.

According to a seventh aspect of the present invention, an image signal composed of a plurality of display gradation data for displaying a plurality of pixels constituting a display image at a predetermined gradation is received from the outside, and roughness when the display image is displayed is generated. A display control method for outputting an image signal compensated to be suppressed,
A plurality of correction gradation data arranged to form a matrix for performing the compensation, and the spatial frequency component of the matrix when the matrix is handled as an image by associating with the plurality of display gradation data A matrix storage step for storing the plurality of corrected gradation data set such that a high-frequency spatial frequency component in a displayable spatial frequency region is larger than a low-frequency spatial frequency component;
Matrix addition for outputting the compensated image signal including display gradation data obtained by adding the plurality of correction gradation data stored in the matrix storage step to the corresponding plurality of display gradation data, respectively. Step part.

  According to the first aspect of the invention, the matrix addition unit supports a plurality of correction gradation data set so that a high-frequency spatial frequency component is larger than a low-frequency spatial frequency component in a displayable spatial frequency region. With a simple configuration that is added to each of the plurality of display gradation data, local roughness is less likely to be perceived by the eyes, and as a whole, the roughness of still images can be eliminated or reduced.

  According to the second aspect of the invention, the number of correction gradation data arranged in the vertical direction is less than half of the number of pixels in the vertical direction of the display image and the correction gradation arranged in the horizontal direction by the matrix storage unit. The plurality of correction gradation data set so that the number of data is less than or equal to half the number of pixels in the horizontal direction of the display image is stored, and the range corresponding to the plurality of correction gradation data is overlapped by the matrix addition unit. The storage capacity required for the matrix storage unit can be reduced by the configuration that is added to each of the plurality of display gradation data selected so as not to become.

  According to the third aspect, the matrix storage unit stores a plurality of correction gradation data arranged to form a plurality of matrices corresponding to colors displayed in a plurality of pixels, and the matrix addition unit stores these correction gradation data. Since the plurality of correction gradation data is added to the plurality of display gradation data for each corresponding color, it is possible to perform compensation according to the display characteristics of the pixels for each color.

  According to the fourth aspect of the invention, the volume unit multiplies a plurality of correction gradation data by a coefficient stored in advance for each corresponding color, and the plurality of correction gradation data multiplied by the high frequency addition unit corresponds. Therefore, the correction gradation data having a suitable size according to the display characteristics of the pixel for each color can be used.

  According to the fifth aspect of the invention, the configuration in which a plurality of coefficients including a coefficient having a value of 0 is stored by the volume unit causes almost a sense of roughness in the display characteristics of the color corresponding to the coefficient set to 0. By compensating the roughness with the correction gradation data when there is no image quality, it is possible to prevent the image quality from being deteriorated.

  According to the sixth aspect, the same effect as in any one of the first to fifth aspects can be achieved in the active matrix display device.

  According to the seventh aspect, the same effect as that of the first aspect can be achieved in the display control method.

<1. Overall Configuration and Operation of Liquid Crystal Display Device>
FIG. 1 is a block diagram showing the overall configuration of an active matrix liquid crystal display device according to an embodiment of the present invention. The liquid crystal display device includes a display control circuit 200, a drive control unit including a source driver (video signal line drive circuit) 300, and a gate driver (scanning signal line drive circuit) 400, and a display unit 500. The display unit 500 includes a plurality (M) of video signal lines SL (1) to SL (M), a plurality (N) of scanning signal lines GL (1) to GL (N), and a plurality of these. A plurality of (M × N) pixels provided corresponding to the intersections of the video signal lines SL (1) to SL (M) and the plurality of scanning signal lines GL (1) to GL (N), respectively. The pixel forming portion corresponding to the intersection of the scanning signal line GL (n) and the video signal line SL (m) is indicated by the reference symbol “P (n, m)”. ), As shown in FIG. 2 and FIG. Here, FIG. 2 schematically shows a configuration of the display unit 500 in the present embodiment, and FIG. 3 shows an equivalent circuit of the pixel formation unit P (n, m) in the display unit 500.

  As shown in FIG. 2 and FIG. 3, each pixel forming portion P (n, m) has a video signal passing through the intersection while the gate terminal is connected to the scanning signal line SL (n) passing through the corresponding intersection. The TFT 10 which is a switching element having a source terminal connected to the line SL (m), the pixel electrode Epix connected to the drain terminal of the TFT 10, and the plurality of pixel formation portions P (i, j) (i = 1) ˜N, j = 1 to M) and a common electrode (also referred to as “counter electrode”) Ecom, and the plurality of pixel formation portions P (i, j) (i = 1 to N, j). = 1 to M) and a liquid crystal layer as an electro-optic element sandwiched between the pixel electrode Epix and the common electrode Ecom.

  Each pixel forming portion P (n, m) displays one of red (R), green (G), and blue (B), and has the same color as shown in FIG. Is formed along the video signal lines SL (1) to SL (M) and the direction along the scanning signal lines GL (1) to GL (N). Are arranged in the order of RGB.

  In each pixel forming portion P (n, m), a liquid crystal capacitor Clc is formed by the pixel electrode Epix and a common electrode Ecom that faces the pixel electrode Epix across the liquid crystal layer, and an auxiliary capacitor Cs is formed in the vicinity thereof. .

  When the scanning signal G (n) applied to the scanning signal line GL (n) becomes active, the TFT 10 is selected and becomes conductive. The drive video signal S (m) is applied to the pixel electrode Ep via the video signal line SL (m). As a result, the applied voltage of the driving video signal S (m) (voltage based on the potential of the common electrode Ec) is applied as a pixel value to the pixel forming portion P (n, m) including the pixel electrode Ep. Written.

  The display control circuit 200 receives a display data signal DAT and a timing control signal TS sent from the outside, and controls a digital image signal DV, a source start pulse signal SSP for controlling the timing of displaying an image on the display unit 500, and a source A clock signal SCK, a latch strobe signal LS, a gate start pulse signal GSP, and a gate clock signal GCK are output.

  Here, the display data signal DAT from the outside is a total of 24 bits of parallel consisting of red display data DR, green display data DG, and blue display data DB, which are 8-bit data to be given to each pixel forming unit. Contains data.

  The source driver 300 receives the digital image signal DV, the source start pulse signal SSP, the source clock signal SCK, and the latch strobe signal LS output from the display control circuit 200, and each pixel forming unit P (n, In order to charge the pixel capacity of m), a driving video signal is applied to each video signal line SL (1) to SL (M). At this time, the source driver 300 sequentially holds the digital image signal DV indicating the voltage to be applied to each of the video signal lines SL (1) to SL (M) at the timing when the pulse of the source clock signal SCK is generated. . The held digital image signal DV is converted into an analog voltage at the timing when the pulse of the latch strobe signal LS is generated. The converted analog voltage is applied simultaneously to all the video signal lines SL (1) to SL (M) as drive video signals. That is, in the present embodiment, the line sequential driving method is adopted as the driving method of the video signal lines SL (1) to SL (M).

  The gate driver 400 applies an active scanning signal to the scanning signal lines GL (1) to GL (N) based on the gate start pulse signal GSP and the gate clock signal GCK output from the display control circuit 200.

  As described above, the driving video signal is applied to the video signal lines SL (1) to SL (M) and the scanning signal is applied to the scanning signal lines GL (1) to GL (N). The image is displayed on the display unit 500. The common electrode Ecom is supplied with a predetermined voltage by a power supply circuit (not shown) and is held at the common electrode potential Vcom.

<2. Configuration and operation of display control circuit>
FIG. 4 is a configuration diagram of the display control circuit 200 in the present embodiment. The display control circuit 200 includes a matrix storage unit 21 that stores a high-frequency matrix corresponding to each color of RGB, which will be described later, a volume unit 22 that multiplies a value constituting the high-frequency matrix by a predetermined value, and a high-frequency matrix for given image data. , A timing control unit 24 for performing timing control, an input data storage unit 25 for storing pixel values (display gradation data) included in the display data signal DAT given from the outside of the apparatus, and an output And an output data storage unit 26 for storing pixel values to be included in the digital image signal DV. The matrix storage unit 21, the input data storage unit 25, and the output data storage unit 26 store data in a predetermined storage area in a storage device such as a semiconductor memory (not shown).

  The timing control unit 24 receives a timing control signal TS sent from the outside, and controls the control signal CT for controlling the operations of the high frequency adding unit 23 and the output data storage unit 26 and the timing for displaying an image on the display unit 500. A source start pulse signal SSP, a source clock signal SCK, a latch strobe signal LS, a gate start pulse signal GSP, and a gate clock signal GCK are output.

  The matrix storage unit 21 stores high-frequency matrices MR, MG, and MB each having p rows and q columns elements (corrected gradation data described later) in a predetermined storage area in a storage device such as a semiconductor memory (not shown). Yes. These high-frequency matrices MR, MG, and MB are for correcting an image to be displayed by a pixel block including pixel formation portions of red (R), green (G), and blue (B), respectively. . Thus, by providing a high-frequency matrix for each color, compensation according to the display characteristics in the pixel formation portion for each color can be performed. In the following, among these high-frequency matrices, the high-frequency matrix MR will be described for convenience of description, and description of the high-frequency matrices MG and MB having the same configuration will be omitted.

  FIG. 5 is a diagram illustrating a high-frequency matrix MR corresponding to red (R). The high frequency matrix MR shown in FIG. 5 is composed of corrected gradation data MR (1, 1) to MR (64, 64) arranged in a matrix of 64 rows and 64 columns. Hereinafter, this corrected gradation data is represented by MR (p, q) (p, q are natural numbers of 64 or less). The corrected gradation data MR (p, q) is 8-bit data here, and has any integer value within a predetermined range of −127 to 127 as a value. For example, the correction gradation data MR (1, 1) is an element in the first row and the first column in the high frequency matrix MR, and its value is 48 as shown in FIG.

  Each value of the correction gradation data MR (p, q) constituting the high frequency matrix MR should be displayed by a pixel block including a red (R) pixel forming portion included in the display portion 500 as described later. This is a value for correcting the image. Therefore, the high-frequency matrix MR is not an image that is displayed as it is by the display unit 500, but can be handled in the same manner as an image to be displayed, and when handled as an image in this way, a predetermined spatial frequency component is used. It can be said that it has.

  Each value of the correction gradation data MR (p, q) constituting the high frequency matrix MR is a high frequency component (high frequency spatial frequency) among the spatial frequency components of the high frequency matrix MR (handled as an image). Component) is set to be larger than a low-frequency component (low-frequency spatial frequency component). Here, when the general image is displayed on the display unit 500, the high-frequency spatial frequency component is a component in a high frequency region among all the spatial frequency components in the spatial frequency region that can be displayed due to the configuration of the device. The low-frequency spatial frequency component indicates a component in the low frequency region.

  In addition, the specific numerical value can be calculated | required with various methods so that the high spatial frequency component in a high frequency matrix may become large. For example, in a method called a stochastic method, one of the values of the correction gradation data constituting the high-frequency matrix is selected, the selected value is randomly changed, and the spatial frequency is calculated each time. As a result, when the high spatial frequency component becomes large, the selected value is changed to a changed value, and when the high spatial frequency component is not large, the selected value remains unchanged and other correction gradations remain unchanged. A series of processes in which one of the data values is selected and a similar calculation process is performed is repeated until a desired result having a high spatial frequency component is obtained.

  FIG. 6 is a diagram showing the spatial frequency characteristics of the high-frequency matrix MR shown in FIG. Note that the vertical and horizontal axes of the graph shown in FIG. 6 represent the frequency of the vertical and horizontal spatial frequency components included in the high frequency matrix MR, respectively, and the height axis indicates the spatial frequency component. Represents the strength of That is, the closer to the peripheral portion of the graph, the higher the frequency of the spatial frequency component, and the central portion of the graph is a direct current (DC) component.

  As shown in FIG. 6, it can be seen that the spatial frequency characteristics of the high frequency matrix MR have a higher spatial frequency component than a lower spatial frequency component, and more specifically, the higher spatial frequency component is higher than in most cases. It turns out that it is what grows.

  Displayed by appropriately adding the correction gradation data of the high frequency matrix having a large spatial frequency component in the high region (high frequency region) to the gradation value of the image displayed on the display unit 500 as will be described later. A noise-like high-frequency component is included in the entire image. This makes it difficult for the eyes to feel the local roughness that should occur in a part of the displayed image, so that it is possible to eliminate or reduce the roughness of the display screen when viewing the displayed image as a whole.

  The volume unit 22 has a predetermined value αR (for example, about 0.2 to 0.3) for each value of the correction gradation data MR (p, q) constituting the high frequency matrix MR stored in the matrix storage unit 21. The corrected high frequency matrix McR composed of each value of the corrected gradation data McR (p, q) multiplied by Similarly, the volume unit 22 sets a predetermined value αG for each value of each correction gradation data MG (p, q) constituting the high frequency matrix MG, and each correction gradation data MB constituting the high frequency matrix MB. A correction high-frequency matrix McG composed of each value of corrected gradation data McG (p, q) obtained by multiplying each value of (p, q) by a predetermined value αB, and correction gradation data McB (p, q) The corrected high frequency matrix McB composed of each value is given to the high frequency adding unit 23.

  In this way, in the configuration in which each element of the high frequency matrix is multiplied by the predetermined values αR, αG, αB, the values of αR, αG, αB are appropriately set according to the display characteristics in the display unit 500 of each color image. By setting, it is possible to use corrected gradation data having a suitable size according to the display characteristics for each color.

  Further, when any one or two of the values of αR, αG, and αB is set to 0, the display characteristics of the color corresponding to the value set to 0 hardly cause a sense of roughness. Further, by compensating the roughness with the correction gradation data, it is possible to prevent the deterioration of the image quality.

  The high frequency adding unit 23 applies the red (R) image, the green (G) image, and the blue (B) image obtained by dividing each display gradation data stored in the input data storage unit 25 for each color RGB. Then, the correction high-frequency matrices McR, McG, and McB corresponding to the corresponding colors are added. This addition is performed on the entire range of each color image, that is, all display gradation data. Hereinafter, the addition operation will be specifically described.

  Here, when the display resolution in the display unit 500 shown in FIG. 1 is VGA, that is, 640 (horizontal) × 480 (vertical), each color image is also composed of 640 × 480 display gradation data. At this time, as can be seen from FIG. 2, M = 640 × 3 and N = 480. Therefore, for example, as shown in FIG. 2, the pixel forming portion constituting the R image has P (1,1), P (1,4), P (1,7),..., P (2,1), P (2, 4),..., Where x is a natural number of 480 or less and y is a natural number of 640 or less, can be represented as P (x, 3y−2).

  The high frequency adding section 23 is display gradation data included in the display data signal DAT sent from the outside, and is to be given to the pixel forming section P (x, 3y-2) that displays the red (R). Each value of the corresponding corrected gradation data McR (p, q) included in the corrected high-frequency matrix McR is sequentially added to the data for each block described later, and the obtained display gradation data is output data. The data is sequentially stored in the storage unit 26.

  For example, assume that the value of display gradation data to be given to P (1,1) is 200. Since the value of the correction gradation data MR (1, 1) included in the high frequency matrix MR corresponding to this is 48 as shown in FIG. 5 (upper left), the value of αR is set to 0.2. At this time, the value of the display gradation data after the addition becomes 210 (≈200 + 48 × 0.2) by rounding off after the decimal point. Similarly, if the value of the display gradation data to be given to P (1,4) and P (1,7) is also 200, the display gradation data after addition given to P (1,4) The value is 182 and the value of the display gradation data after addition given to P (1,7) is 205.

  Thus, when the addition using the corrected high frequency matrix McR of 64 × 64 is completed with the pixel forming portion P (p, 3q−2) as one block, the high frequency adding portion 23 is not added again. The same applies to the display gradation data to be given to the pixel forming portion P (p, 3 (q + 64) -2) constituting the block adjacent to the right side of the block among the pixel forming portions that display red (R). To the corresponding corrected gradation data McR (p, q) included in the corrected high-frequency matrix McR.

  For example, display gradations to be given to the pixel forming portions P (1, 192), P (1, 195), P (1, 198),..., P (2, 192), P (2, 195),. The corresponding corrected gradation data McR (p, q) included in the corrected high-frequency matrix McR is added to the data.

  When there is no adjacent block on the right side of the block, the high frequency adding unit 23 further displays the pixel forming unit P (p, q) among the pixel forming units that display red (R) that is not added. Similarly, with respect to the display gradation data to be given to the pixel forming portion P (p + 64, 3q−2) constituting the block adjacent to the lower side, corresponding correction gradation data McR ( p, q) are added, and the above-described addition processing is sequentially performed from the upper left block to the lower right block in the same manner.

  When the addition is completed for all the display gradation data to be given to the pixel forming unit displaying red (R), the high frequency adding unit 23 similarly displays green (G) and blue (B). Addition is performed on all the display gradation data to be given to the pixel formation portion.

  When the addition processing by the high-frequency adding unit 23 as described above is completed, the output data storage unit 26 stores compensated display gradation data to be given to all the pixel forming units included in the display unit 500. The output data storage unit 26 outputs the digital image signal DV to be given to the source driver 300 by reading the display gradation data at an appropriate timing according to the control signal CT from the timing control unit 24.

  This digital image signal DV is supplied to the source driver 300 (as parallel data of 24 bits in total of 8 bits for each of RGB). In the source driver 300, the digital image signal DV is converted into an analog voltage for each color and applied to the corresponding video signal lines SL (1) to SL (M) as driving video signals. The voltages applied as video signals for driving to the video signal lines SL (1) to SL (M) in this way are the TFTs 10 that are turned on by sequential application of active scanning signals by the gate driver 400, respectively. Is applied to the pixel electrode Epix of each pixel formation portion P (n, m) and is held in the pixel capacitance of the pixel formation portion P (n, m). An image is displayed by applying the holding voltage in the pixel capacitor to the liquid crystal and controlling the light transmittance of the display unit 500. As described above, the feeling of roughness in the image is eliminated or reduced.

<3. Effect>
As described above, the display control circuit and the active matrix display device including the display control circuit according to the present embodiment have a simple configuration in which a high-frequency matrix having a large high-frequency spatial frequency component is added to image data, and there is no local roughness. It becomes difficult to perceive the eyes, and it is possible to eliminate or reduce the feeling of roughness (particularly still images) on the display screen as a whole.

<4. Modification>
In the above embodiment, the size of the high frequency matrix is 64 × 64 as shown in FIG. 5, but may be smaller as long as the spatial frequency component of the high frequency can be increased. The image may be large enough not to exceed the size of the image to be displayed. However, as shown in FIG. 5, by using a high-frequency matrix that is small (that is, the number of correction gradation data is small) that is half or less of the size of a general display screen (for example, 640 × 480 dots in VGA), The storage capacity of the matrix storage unit 21 can be reduced.

  In the above embodiment, the matrix storage unit 21 stores one high-frequency matrix MR, MG, and MB, but each may store two or more, or store only one commonly used. You may do it. In a configuration in which two or more high-frequency matrices are stored, a spatial frequency component suitable for eliminating or reducing the feeling of roughness according to the characteristic variation of the characteristic pixel forming portion in the display portion of the liquid crystal display device is included. The high-frequency matrix can be appropriately selected at the time of manufacture or use, and the rough feeling can be eliminated or reduced according to the characteristics of each display device with a simple configuration.

  In the above description, the active matrix type liquid crystal display device has been described as an example. However, as long as the display device is an active matrix type display device and its switching elements have characteristic variations, other than the liquid crystal display device. The present invention can be applied.

1 is a block diagram illustrating an overall configuration of an active matrix liquid crystal display device according to an embodiment of the present invention. It is a figure which shows typically the structure of the display part of an active matrix liquid crystal display device. It is a circuit diagram showing an equivalent circuit of a pixel formation portion in an active matrix type liquid crystal display device. It is a block diagram which shows the structure of the display control circuit in the said embodiment. In the said embodiment, it is a figure which shows the example of a high frequency matrix. In the said embodiment, it is a figure which shows the spatial frequency characteristic of the example of a high frequency matrix.

Explanation of symbols

10 ... TFT (switching element)
DESCRIPTION OF SYMBOLS 21 ... Matrix storage part 22 ... Volume part 23 ... High frequency addition part 24 ... Timing control part 25 ... Input data storage part 26 ... Output data storage part 200 ... Display control circuit 300 ... Source driver 400 ... Gate driver 500 ... Display part DAT ... Display data signal DV ... Digital image signal Clc ... Liquid crystal capacitance Cs ... Parasitic capacitance Ecom ... Common electrode Epix ... Pixel electrode GL (n) ... Scanning signal line (n = 1 to N)
SL (m): Data signal line (m = 1 to M)
P (n, m): Pixel formation portion (n = 1 to N, m = 1 to M)

Claims (7)

An image signal composed of a plurality of display gradation data for displaying a plurality of pixels constituting the display image at a predetermined gradation is received from the outside, and compensated so that roughness when the display image is displayed is suppressed. A display control circuit for outputting a received image signal,
A plurality of correction gradation data arranged to form a matrix for performing the compensation, and a spatial frequency component of the matrix when the matrix is handled as an image by associating with the plurality of display gradation data A matrix storage unit for storing the plurality of corrected gradation data set such that a high frequency spatial frequency component in a displayable spatial frequency region is larger than a low frequency spatial frequency component;
Matrix addition for outputting the compensated image signal including display gradation data obtained by adding a plurality of correction gradation data stored in the matrix storage unit to the corresponding display gradation data, respectively. A display control circuit. The matrix storage unit performs correction in which the number of correction gradation data arranged in the vertical direction of the matrix is less than half of the number of pixels arranged in the vertical direction of the display image and arranged in the horizontal direction of the matrix. Storing the plurality of corrected gradation data set so that the number of gradation data is less than or equal to half the number of pixels arranged in the horizontal direction of the display image;
The matrix adding unit adds a plurality of correction gradation data stored in the matrix storage unit to the plurality of display gradation data selected so that corresponding ranges do not overlap each other. The display control circuit according to claim 1, wherein the compensated image signal including tone data is output. The matrix storage unit stores the plurality of correction gradation data arranged to form a plurality of matrices corresponding to colors displayed in the plurality of pixels;
The matrix adding unit includes display gradation data obtained by adding the plurality of correction gradation data stored in the matrix storage unit to the plurality of display gradation data for each corresponding color. The display control circuit according to claim 1, wherein a compensated image signal is output. The matrix adding unit includes:
A volume unit for multiplying the plurality of corrected gradation data stored in the matrix storage unit by a coefficient stored in advance for each corresponding color;
The compensated image signal including display gradation data obtained by adding the plurality of corrected gradation data multiplied by the volume unit to the plurality of display gradation data for each corresponding color is output. The display control circuit according to claim 3, further comprising: a high-frequency addition unit that performs processing.   The display control circuit according to claim 4, wherein the volume unit stores the plurality of coefficients including a coefficient having a value of zero. A display control circuit according to any one of claims 1 to 5,
A plurality of video signal lines for transmitting a plurality of video signals corresponding to image signals output from the display control circuit;
A plurality of scanning signal lines intersecting with the plurality of video signal lines;
The plurality of video signal lines and the plurality of scanning signal lines are arranged in a matrix corresponding to the intersections of the plurality of scanning signal lines, respectively, and are in a conductive state or in accordance with signals applied to the scanning signal lines passing through the corresponding intersections. A plurality of pixel forming portions each including a switching element to be cut off;
An active matrix display device comprising: a drive control circuit for driving the plurality of video signal lines and the plurality of scanning signal lines. An image signal composed of a plurality of display gradation data for displaying a plurality of pixels constituting the display image at a predetermined gradation is received from the outside, and compensated so that roughness when the display image is displayed is suppressed. A display control method for outputting a received image signal,
A plurality of correction gradation data arranged to form a matrix for performing the compensation, and the spatial frequency component of the matrix when the matrix is handled as an image by associating with the plurality of display gradation data A matrix storage step for storing the plurality of corrected gradation data set such that a high-frequency spatial frequency component in a displayable spatial frequency region is larger than a low-frequency spatial frequency component;
Matrix addition for outputting the compensated image signal including display gradation data obtained by adding the plurality of correction gradation data stored in the matrix storage step to the corresponding plurality of display gradation data, respectively. A display control method including a step unit.

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