JP2009288811A - Control circuit of liquid crystal display for drive compensation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control circuit of a liquid crystal display which generates more suitable compensation values or compensated display driving data. <P>SOLUTION: A display driving data generation part includes a conversion table 4b for storing compensation data corresponding to the combinations of upper bits between image data nFi of a current frame and post-drive status data (n-1)Fp of a preceding frame and an interpolation calculation part for generating interpolated compensation data by applying interpolation calculation to the compensation data read out from the conversion table in accordance with the lower bits of the image data of the current frame and the post-drive status data of the preceding frame. The conversion table individually includes a singular point conversion table to be used when the post-dive status data of the preceding frame is first data and an ordinary point conversion table to be used for the post-drive status data other than the first data. The singular point conversion table or the ordinary point conversion table is selected in accordance with whether the post-drive status data of the preceding frame is the first data or not. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control circuit for a liquid crystal display device, and in particular, enables high-speed response by adding a compensation value to a driving voltage of a cell to compensate for the driving, and different compensation value conversion tables depending on the state of the previous frame. The present invention relates to a control circuit for a liquid crystal display device that enables more accurate drive compensation.

  Liquid crystal display devices are widely used as energy-saving and space-saving display devices. In recent years, it has been attracting attention as a television display device for displaying moving images. The liquid crystal display panel has a source electrode to which a display driving voltage corresponding to the image data of the current frame is applied, a gate electrode driven at a scanning timing, and a cell transistor and a pixel electrode provided at the intersection of them. Then, a display drive voltage is applied to the liquid crystal layer between the pixel electrodes through the cell transistor to change the transmittance of the liquid crystal layer, thereby displaying a desired image.

  The liquid crystal material generally does not have a very good response characteristic, and may not change to a state corresponding to the input gradation data within one frame period, and the poor response characteristic causes a reduction in the image quality of moving image display. In order to solve such a slow response characteristic, a drive compensation method has been proposed (for example, Patent Documents 1, 2, and 3 below).

  In Patent Document 1, display drive data for current frame image data is added to and subtracted from the current frame image data with a compensation value corresponding to the combination of the post-drive state data of the previous frame and the current frame image data (hereinafter referred to as the following) It is referred to as addition for short). In addition, since the liquid crystal layer is not always in the state as the display drive data even when driven by the display drive voltage corresponding to the display drive data, the combination of the post-drive state data of the previous frame and the input gradation data in the current frame is used. It is described that a corresponding difference value is added to or subtracted from the image data of the current frame (hereinafter abbreviated as “addition”) to obtain post-drive state data and store it in the frame memory.

  Further, in Patent Document 1, in order to reduce the data capacity of the conversion table for obtaining the compensation value and the difference value, the compensation value and the difference value for the combination of the post-drive state data of the previous frame and the upper bits of the image data of the current frame are set. It is described that it is stored in a conversion table and an interpolation operation is performed using lower bits.

JP 2002-297104 A Corresponding US publication: US-2002-0140652-A1 Japanese Patent Laid-Open No. 2002-6285 JP 2002-202763 A

  However, the characteristic curve of the compensation value differs greatly between the case where the post-drive state of the previous frame is the gradation “0” and the case of the other gradations. Therefore, a compensation value that is not equal is obtained.

  FIG. 1 is a diagram showing the relationship between the post-drive state of the previous frame and the compensation value. The horizontal axis indicates the starting point gradation indicating the post-drive state of the previous frame, the vertical axis indicates the compensation value, and the characteristic curve in FIG. 1 indicates that the end point gradation indicating the image data of the current frame is 48/256 (48 out of 256 gradations). This is an example. When the starting gray level of the previous frame is “0”, the compensation value is as large as “29”. However, when the starting gray level is larger than “0”, the compensation value decreases rapidly, and the starting gray level is, for example, “2”. As it becomes larger, the compensation value changes almost linearly. It is understood that in the region where the starting point gradation exceeds “16”, the compensation value decreases linearly (linearly).

  Because of this characteristic, when the starting point gradation is between 0/255 and 16/255, the linear interpolation operation is performed on the two points C (0) and C (16). As shown, a compensation value different from the solid characteristic curve is required. Specifically, if the starting point gradation is 8/255, the compensation value is excessively increased by dx in the figure. Along with this, when a value obtained by adding a compensation value obtained by linear interpolation to the current frame image data is used as display drive data, there is a problem that appropriate drive compensation is not performed. If compensation value data for all starting gradations is stored in the conversion table, it is possible to generate a compensation value according to the solid characteristic curve. However, if this is done, the data capacity of the conversion table becomes enormous, leading to an increase in cost. .

  Another problem is that the frame frequency can be arbitrarily set in the host computer connected to the liquid crystal display device, so the liquid crystal display device is required to perform display control corresponding to different frame frequencies. Is done. However, in the conventional drive compensation method, since a uniform table is used regardless of the frame frequency, the same drive compensation is performed regardless of whether the frame period is long or short. Therefore, when the frame period is short, the compensation tends to be insufficient, and when the frame period is long, the compensation tends to be excessive. As a result, there is a problem that appropriate drive compensation is not performed.

  Accordingly, an object of the present invention is to provide a control circuit for a liquid crystal display device capable of performing appropriate drive compensation.

  To achieve the above object, according to the first aspect of the present invention, in the control circuit of the liquid crystal display device, display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame is generated. A conversion table having a display drive data generation unit, which stores compensation data or compensation display drive data corresponding to a combination of higher-order bits of image data of the current frame and post-drive state data of the previous frame Then, the compensation data or compensation display drive data read out from the conversion table is interpolated according to the lower bits of the image data of the current frame and the post-drive status data of the previous frame to obtain the interpolation compensation data or the interpolation compensation display. An interpolation calculation unit for generating drive data. The conversion table includes a singular point conversion table when the post-drive state data of the previous frame is the first data, and a normal point conversion table for the post-drive state data of the previous frame other than the first data. In addition, the display drive data generation unit selects the singular point conversion table or the normal point conversion table according to whether the post-drive state data of the previous frame is the first data.

  According to the first aspect of the invention, the conversion table is divided into a singular point conversion table when the post-drive state data of the previous frame is the first data, and a normal point conversion table when the conversion data is other than the first data. These two conversion tables are selected by the post-drive state data of the previous frame. Therefore, when the post-drive state data of the previous frame is a normal point other than the singular point, the influence of the characteristic at the singular point can be eliminated, and more accurate correction data or corrected display drive data can be obtained. .

  In order to achieve the above object, according to a second aspect of the present invention, in the control circuit of the liquid crystal display device, display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame is generated. A conversion table having a display drive data generation unit, which stores compensation data or compensation display drive data corresponding to a combination of higher-order bits of image data of the current frame and post-drive state data of the previous frame Then, the compensation data or compensation display drive data read out from the conversion table is interpolated according to the lower bits of the image data of the current frame and the post-drive status data of the previous frame to obtain the interpolation compensation data or the interpolation compensation display. An interpolation calculation unit for generating drive data. The interpolation calculation unit includes a singular point interpolation calculation unit when the post-drive state data of the previous frame is the first data, and a normal point interpolation calculation unit for the post-drive state data of the previous frame other than the first data; Further, the display drive data generation unit selects the singular point interpolation calculation unit or the normal point interpolation calculation unit according to whether the post-drive state data of the previous frame is the first data.

  According to the second aspect of the present invention, the singular point interpolation calculation unit when the interpolation calculation unit is in the first frame after the driving state data of the previous frame and the normal point interpolation calculation unit when it is other than the first data These two interpolation operation units are selected by the post-drive state data of the previous frame. Therefore, when the post-drive state data of the previous frame is a singular point, the first interpolation calculation, for example, non-linear interpolation calculation is used, and when it is the other normal point, the second interpolation calculation, for example, linear interpolation calculation, is used. Therefore, more accurate correction data or corrected display drive data can be obtained.

  By combining the first aspect and the second aspect of the invention, more accurate compensation data or compensation display drive data can be obtained.

  In order to achieve the above object, in the third aspect of the present invention, display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame is generated in the control circuit of the liquid crystal display device. A display drive data generation unit, and the display drive data generation unit includes a conversion table that stores compensation data or compensation display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame. The conversion table includes a first conversion table corresponding to the first frame frequency and a second conversion table corresponding to the second frame frequency. Further, the display drive data generation unit performs interpolation calculation (including extrapolation calculation) on the compensation data or the compensation display drive data read from the first and second conversion tables according to the current frame frequency. It has an interpolation calculation unit that generates interpolation compensation data or interpolation compensation display drive data.

  According to the third aspect, compensation data or compensation display drive data that is optimal for the frame frequency being driven can be generated, so that more appropriate drive compensation can be performed.

  As described above, according to the present invention, more appropriate compensation value or compensation display drive data can be generated.

It is a figure which shows the relationship between the post-driving state of a front frame, and a compensation value. It is a schematic block diagram of a liquid crystal display device. It is a block diagram of the liquid crystal display device in 1st Embodiment. It is a graph which shows an example of the conversion table of a compensation value. It is a graph which shows the normal point conversion table 4b2 of FIG.4 (B), and the singular point conversion table 4b1 of FIG.4 (C). It is a block diagram of the liquid crystal display device in 2nd Embodiment. It is a figure which shows an example of the two interpolation calculations in 2nd Embodiment. It is a block diagram of the liquid crystal display device in the modification of 2nd Embodiment. It is a block diagram of the liquid crystal display device in 3rd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. However, the protection scope of the present invention is not limited to the following embodiments, but extends to the invention described in the claims and equivalents thereof.

  FIG. 2 is a schematic configuration diagram of the liquid crystal display device. In this configuration, the scanning drive signal Sd of the gate driver 2 is supplied to a gate electrode line (not shown) of the liquid crystal display panel 1, and the display driving signal Vd of the source driver 3 is supplied to a source electrode line (not shown). The control circuit 20 includes a display drive data generation unit 4 that generates display drive data nFo from input image data nFi, and post-drive state data nFp and (n-1) Fp of the current frame nF and the previous frame (n-1) F. And a circuit for generating a gate driver control signal GDC and a source driver control signal SDC (not shown).

  The image data to be displayed in the current frame is the current frame image data nFi. By adding the compensation value H to the current frame image data nFi, display drive data nFo (= nFi + H) of the current frame is generated. However, even if it is driven with the display drive data nFo, the post-drive state of the liquid crystal layer may not be a desired state, so post-drive state data nFp that is different from the current frame image data nFi is generated in each frame. Stored in the frame memory 5.

  In the configuration of FIG. 2, the display drive data generation unit 4 performs compensation corresponding to the combination of the input current frame image data nFi and the previous frame drive state data (n−1) Fp stored in the frame memory 5. The value H is read from the compensation conversion table 4b. In order to reduce the data amount of the compensation conversion table 4b, a compensation value H is stored in the table corresponding to the upper bits of the current frame image data nFi and the previous frame driving state data (n-1) Fp. In the interpolation calculation unit 4d, interpolation calculation is performed according to the lower bits of the current frame image data nFi and the previous frame drive state data (n-1) Fp. For this purpose, the input image data conversion unit 4a separates the 8-bit input image data nFi and the post-frame drive state data (n-1) Fp into 4-bit upper bits and 2-bit lower bits, respectively. These are supplied to the compensation conversion table 4b and the interpolation calculator 4d, respectively. In the following example, the remaining 2 least significant bits are ignored in the interpolation calculation. However, the interpolation calculation may be performed using all the lower 4 bits. In the calculator 4 c, the compensation value H obtained by the interpolation calculation is added to the current frame image data nFi, and the display drive data nFo = nFi + H is supplied to the source driver 3. The digital data up to here is D / A converted by the source driver 3 and supplied to the display panel 1 as an analog display drive signal Vd.

  In the compensation conversion table 4b, display drive data nFo obtained by adding the compensation value H to the current frame display data nFi may be stored instead of the compensation value. However, since the display drive data nFo is 8-bit data, there is a disadvantage that the data capacity of the conversion table 4b increases. On the other hand, since the compensation value H is small, it can be data with fewer bits, so the data capacity of the conversion table 4b can be reduced. Therefore, in the following embodiment, an example will be described in which the compensation value H is stored in the conversion table and is added to the current frame image data nFi by the calculator 4c. The post-drive state data generation unit 4x generates post-drive state data nFp of the current frame from the current frame image data nFi and the previous frame drive state data (n−1) Fp. This post-drive state data generation is described in detail in the above-mentioned Patent Document 1.

  FIG. 3 is a configuration diagram of the liquid crystal display device according to the first embodiment. The first embodiment will be described in comparison with the schematic configuration diagram of FIG. First, the compensation conversion table includes the first compensation conversion table 4b1 when the post-drive state data (n-1) Fp of the previous frame is the gradation "0" and the second compensation when the gradation is other than that. It consists of a conversion table 4b2. In addition to the post-drive state data, the frame memory 5 stores a singular point flag FL generated by the flag generation unit 4h when the post-drive state data nFp is the gradation “0”. In this embodiment, the frame memory stores only the upper 4 bits and the lower 2 bits of the 8-bit (256 gradations) post-drive state data nFp and does not store the least significant 2 bits. Is generated and stored.

  FIG. 4 is a chart showing an example of a compensation value conversion table. In each conversion table, a compensation value H is stored corresponding to a combination of post-frame drive state data (start point gradation) (n−1) Fp and current frame image data (end point gradation) nFi. The value in the cell is the compensation value H. As described above, since the table corresponds to the upper 4 bits of the state data after the previous frame drive (start point gradation) (n-1) Fp and the current frame image data (end point gradation) nFi, each table has 17 gradations. Corresponding compensation values are stored.

  FIG. 4A corresponds to the conventional compensation conversion table 4b, and the state data (start point gradation) (n-1) Fp after driving the previous frame and the current frame image data (end point gradation) nFi are 17 respectively. 17 × 17 = 289 compensation values are stored corresponding to the gray scales. The data capacity can be reduced as compared with storing 256 × 256 compensation values corresponding to all gradations 256.

  The compensation value corresponding to the end point gradation in the column where the end point gradation of the table is 48/255 is shown in FIG. As described with reference to FIG. 1, since there is no linear characteristic between the start point gradations “0” and “16”, using the compensation value corresponding to the start point gradation “0”, interpolation can be performed. Incorrect compensation values are obtained. Therefore, in the first embodiment, a table in which the post-drive state data (start point gradation) (n−1) Fp of the previous frame is “0” is provided as the singular point conversion table 4b1. Then, a normal point conversion table 4b2 to be referred to when the post-drive state data (start point gradation) (n−1) Fp of the previous frame is a gradation value other than “0” is separately provided.

  FIG. 4B is an example of the normal point table 4b2. In this example, the post-drive state data (start point gradation) (n−1) Fp of the previous frame is “2”, “16”, “32”, “48”. . . For “255”, it has a compensation value corresponding to image data (end point gradation) nFi of 17 current frames. Further, FIG. 4C is an example of the singular point table 4b1, and in this example, 17 states when the post-drive state data (start point gradation) (n−1) Fp of the previous frame is “0”. It has only the compensation value corresponding to the image data (end point gradation) nFi of the current frame.

  FIG. 5 is a graph showing the normal point conversion table 4b2 in FIG. 4B and the singular point conversion table 4b1 in FIG. 4C. The table of FIG. 4 is merely shown in the graph. In FIG. 5, the horizontal axis indicates 17 points of the end point gradation which is the image data nFi of the current frame, and the vertical axis indicates the compensation value data. The normal point conversion table 4b2 shows a compensation value graph for 17 starting gradations 2/255, 16/255 to 255/255. The singular point conversion table 4b1 shows a compensation value graph for one starting point gradation 0/255.

  Returning to FIG. 3, the input image data conversion unit 4a adds the image data (end point gradation) nFi of the current frame to the first compensation conversion table 4b1 for the singular point and the second compensation conversion table 4b2 for the normal point. The upper 4 bits of the post-drive state data (start point gradation) (n−1) Fp of the previous frame are supplied as the input address 10. In response to this, the normal point conversion table 4b2 outputs the compensation value of the cell corresponding to the input address and the compensation values of the three cells of high gradation adjacent thereto, in total, the four compensation values H2. On the other hand, the singularity conversion table 4b1 outputs two compensation values H1 in total, that is, the compensation value of the cell corresponding to the input address and the compensation value of the high gradation cell adjacent thereto. In the singular point conversion table 4 b 1, only the compensation value of the post-drive state data (end point gradation) of the previous frame is stored as “0”, so the post-drive state data of the previous frame at the input address 10 has the gradation “ In the case other than “0”, no compensation value is output.

  The selector 4f selects the compensation value H1 or H2 according to the flag FL in the frame memory 5, and outputs the selected compensation value H to the interpolation calculator. That is, if the flag FL is the post-drive state data (start point gradation) (n−1) Fp of the previous frame is “0”, the compensation value H1 is selected, and if it is not “0”, the compensation value H2 is selected. The

  The interpolation calculator 4d converts the compensation value H3 selected by the selector into the lower bits of the current frame image data (end point gradation) nFi and the previous frame post-drive state data (start point gradation) (n-1) Fp. Based on this, an interpolation calculation is performed to obtain a compensation value H. Since the interpolation operation has almost linear characteristics except for the gradation “0” of the singular point as shown in FIG. 1, linear interpolation is performed.

  Four compensation values are output from the normal point conversion table 4b2. In the example of FIG. 4B, when the starting point gradation corresponding to the higher-order bit 10 is 16/255 and the end point gradation is 48/255, the compensation value “17” and a higher starting point adjacent thereto are provided. The compensation values “9”, “24”, and “16” of the gradation 32/255 and the end gradation 64/255 are read out. An interpolated compensation value H is obtained by performing a weighted interpolation calculation using the lower bits 12 on these four compensation values. As described above, since the lower bits 12 are 2 bits, one of the interpolation values obtained by dividing adjacent compensation values into four equal parts is calculated. Since the low-order bit 12 is 2 bits, the starting gradation 2/255 is handled substantially the same as the starting gradation 0/255 in the interpolation calculation. Therefore, the minimum starting point gradation of the normal point conversion table 4b2 may be 1/255, 3/255 according to the characteristics of FIG. If the lower-order bit 12 is 4 bits, the interpolation calculator 4d calculates any interpolation value obtained by dividing the adjacent interpolation value into 16 equal parts.

  On the other hand, since two compensation values for the starting point gradation 0/255 are read from the singular point table 4b1, the interpolation calculator 4d performs weighted interpolation calculation on the two compensation values using the lower-order bits of the end point gradation, Interpolated compensation value H is obtained. In the present embodiment, the singular point conversion table 4b1 stores only compensation values for the start point gradations 0/255, but stores compensation values for the start point gradations 4/255, 8/255, and 12/255, respectively. May be. In that case, the minimum starting point gradation of the normal point conversion table 4b2 is 16/255. That is, the singular point conversion table is referred to between the starting point gradations 0 to 16, and the normal point conversion table is referred to for the starting point gradations 16 to 255. In the case of a compensation value from the singular point conversion table, interpolation calculation is performed for the end point gradation, and in the case of the compensation value from the normal point conversion table, interpolation calculation is performed for both the start point gradation and the end point gradation. .

  The arithmetic unit 4 c adds the compensation value H obtained by the interpolation calculation to the image data nFi of the current frame, calculates the display drive data nFo, and supplies it to the source driver 3. The source driver 3 generates an analog display drive signal Vd corresponding to the display drive data nFo and supplies it to the display panel 1.

  In the first embodiment, the compensation value conversion table is provided separately from the normal point compensation value conversion table for singular points having different characteristics, and the singular point conversion table is used when the post-drive state data of the previous frame corresponds to the singular point. Since the compensation value is read out from, a more accurate compensation value can be calculated. The compensation value conversion table may store display drive data obtained by adding compensation values to the image data of the current frame.

  FIG. 6 is a configuration diagram of a liquid crystal display device according to the second embodiment. The difference from FIG. 2 of this configuration will be described. The first interpolation calculator 4d1 in which the interpolation calculator performs the interpolation calculation of the compensation value including the singular point, and the second interpolation in which the interpolation calculation of the compensation value at the normal point is performed. The selector 4f selects one of the compensation values H1 and H2 obtained by the respective interpolation calculators 4d1 and 4d2 based on the singular point flag FL. In this example, the flag generation unit is not provided, but by storing all the 8-bit post-drive state data in the frame memory 5, the input image data conversion unit 4a is able to start from the post-drive state data of the previous frame. It is possible to generate the flag FL by determining whether or not it is a singular point.

  As shown in FIG. 1, the compensation value has a non-linear characteristic when the starting point gradation is between 0/255 and 16/255, but is linear when the starting point gradation is between 16/255 and 255/255. It has become. Therefore, in the second embodiment, when the post-startup state data (start point gradation) (n-1) Fp of the previous frame is 0/255 of the singular point, the interpolation calculation is non-linear interpolation, and the normal data other than the singular point is used. If it is a point, the interpolation calculation is linear interpolation.

  FIG. 7 is a diagram illustrating an example of two interpolation calculations in the second embodiment. FIG. 7A shows the interpolation formula of the normal point interpolation calculator 4d2, and FIG. 7B shows the interpolation formula of the singular point interpolation calculator 4d1. In the case of a normal point, both the start point gradation and the end point gradation are equally divided and interpolated (linear interpolation), whereas in the case of a singular point, the start point gradation is not evenly divided (nonlinear interpolation). ) And end point gradation is equally divided and interpolated. In non-uniform division interpolation, interpolation calculation is performed at 4: 2: 1: 1 in the start gradation direction (vertical direction). That is, as shown in FIG. 1, the characteristic between the singular point 0/255 and the adjacent gradation point 16/255 has a downward convex characteristic, so that the above 4: 2: 1: 1. By performing the non-linear interpolation, an accurate compensation value corresponding to the characteristic can be interpolated.

  FIG. 8 is a configuration diagram of a liquid crystal display device according to a modification of the second embodiment. In this example, two interpolation calculators 4d1 and 4d2 are provided similarly to the configuration shown in FIG. 6, and the compensation value conversion table is divided into a singular point table 4b1 and a normal point table 4b2. . Then, the interpolation calculation unit 4d1 interpolates the two compensation values read from the singular point compensation value table 4b1, and interpolates from the four compensation values read from the normal point compensation value table 4b2. The interpolation calculation between the start gradations of 2/255 and 16/255 is performed by the first interpolation calculator 4d1, and the interpolation calculation with the start gradations of 16/255 or more is performed by the second interpolation calculator 4d2. . As in FIG. 6, the interpolation calculator 4d1 performs nonlinear interpolation calculation between the start point gradations and linear interpolation calculation between the end point gradations, and the interpolation calculator 4d2 performs both linear interpolation calculations.

  Accordingly, the flag generation unit 4h generates the first flag FL1 when the post-drive state data nFp is “0” and the second flag FL2 when the post-drive state data nFp is “0” to “16”, and the frame memory 5 is stored. Then, the selector 4f1 selects either the compensation value H1 or H21 according to the first flag FL1. The selector 4f2 selects either the compensation value H24 or H25 according to the second flag FL2.

  According to the above configuration, when the post-drive state data (n-1) Fp of the previous frame is 0/255, the compensation value H1 of the first compensation value conversion table 4b1 is read out, and the interpolation calculator 4d1 Linear interpolation is performed between the end point gradations and supplied as a compensation value H to the calculator 4c. On the other hand, when the post-drive state data (n-1) Fp of the previous frame is 2/255 to 16/255, the compensation value H21 of the second compensation value conversion table 4b2 is read and the interpolation calculator 4d1 is the starting point. Non-linear interpolation is performed between gradations, and linear interpolation is performed between end point gradations. Further, when the post-drive state data (n-1) Fp of the previous frame is 16/255 to 255/255, the compensation value H22 of the second compensation value conversion table 4b2 is read out, and the interpolation calculator 4d2 is the starting point. Linear interpolation is performed between the gradations and between the end gradations.

  FIG. 9 is a configuration diagram of a liquid crystal display device according to the third embodiment. In the host computer that supplies image data to the liquid crystal display device, when an arbitrary frequency can be selected, the frame frequency or the frame period differs accordingly. Since drive compensation is a drive method in which a compensation value is added to image data in order to compensate that each pixel is in the state of input image data within the frame period, the compensation value can be reduced as the frame period becomes longer. If the frame period is shortened, the compensation value is required to be increased.

  Therefore, in the third embodiment, the compensation value conversion table includes the first compensation value conversion table 4b-f1 storing the compensation value at the first frequency, and the compensation value at the second frequency. The frequency compensation calculator 4g is composed of the stored second compensation value conversion table 4b-f2, and the frequency interpolation computing unit 4g is arranged inside or outside the two compensation values H31 and H32 according to the frequency F detected by the frame frequency detection unit 4y. Interpolate the compensation value. Strictly speaking, the outside of the first and second frequencies is extrapolated.

  FIG. 9 shows an example of frequency interpolation calculation. The first frequency is set to 50 Hz, the second frequency is set to 73 Hz, and the frame frequency detection unit 4y divides the interval into four to detect three types of frequencies. From the compensation value A in the first compensation value conversion table 4b-f1, the compensation value B in the second compensation value change table 4b-f2, and the detected frequency F, the frequency interpolation calculator 4g performs linear interpolation. A compensation value H33 corresponding to the detected frequency is obtained. Also in the third embodiment, the interpolation calculation by the lower bits 12 is performed by the interpolation calculator 4d. Therefore, the compensation values H31 and H32 are four compensation values. The order of the frequency interpolation calculator 4g and the interpolation calculator 4d may be reversed.

  As described above, a more appropriate compensation value can be interpolated by providing a compensation value conversion table separately for singular points having different compensation value characteristics or by using different interpolation calculators. Also, by providing a compensation value conversion table corresponding to the minimum and maximum frame frequencies, a more appropriate compensation value can be interpolated for different frame frequencies.

  In the above embodiment, the gradation value of the previous frame is set to the post-drive state data (n−1) Fp. However, when the post-drive state data generation unit 4x is not provided, the state of the input image data nFi is obtained by compensation driving. The gradation value of the previous frame can be set to the image data (n−1) Fi of the previous frame. However, the compensation value may not be appropriate if the post-drive state does not necessarily match the image data.

  The exemplary embodiments are summarized as follows.

(Supplementary note 1) In the control circuit of the liquid crystal display device,
A display drive data generation unit that generates display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame;
The display drive data generation unit
A conversion table for storing compensation data or compensation display drive data corresponding to a combination of higher-order bits of image data of the current frame and post-drive state data of the previous frame;
The compensation data or compensation display drive data read from the conversion table is interpolated according to the lower-order bits of the current frame image data and the post-drive state data of the previous frame, and the interpolation compensation data or the interpolation compensation display drive data. An interpolation calculation unit for generating
The conversion table includes a singular point conversion table when the post-drive state data of the previous frame is the first data, and a normal point conversion table for the post-drive state data of the previous frame other than the first data. ,
Further, the display drive data generation unit selects the singular point conversion table or the normal point conversion table according to whether or not the post-drive state data of the previous frame is the first data. Control circuit.

(Appendix 2) In Appendix 1,
And a frame memory for storing the post-drive state data. The frame memory stores a flag indicating whether or not the post-drive state data is the first data. A control circuit for a liquid crystal display device, wherein a singular point conversion table or a normal point conversion table is selected.

(Appendix 3) In Appendix 1,
From the singularity conversion table, two adjacent compensation data or compensation display drive data corresponding to the upper bits of the image data of the current frame are read out, and an interpolation operation is performed according to the lower bits of the image data of the current frame. Is done,
From the normal point conversion table, four adjacent compensation data or compensation display drive data corresponding to the post-drive state data of the previous frame and the upper bits of the image data of the current frame are read, and the drive of the previous frame is read. A control circuit for a liquid crystal display device, wherein an interpolation operation is performed in accordance with the lower state bits of the rear state data and the image data of the current frame.

(Supplementary Note 4) In the control circuit of the liquid crystal display device,
A display drive data generation unit that generates display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame;
The display drive data generation unit
A conversion table for storing compensation data or compensation display drive data corresponding to a combination of higher-order bits of image data of the current frame and post-drive state data of the previous frame;
The compensation data or compensation display drive data read from the conversion table is interpolated according to the lower-order bits of the current frame image data and the post-drive state data of the previous frame, and the interpolation compensation data or the interpolation compensation display drive data. An interpolation calculation unit for generating
The interpolation calculation unit includes a singular point interpolation calculation unit when the post-drive state data of the previous frame is the first data, and a normal point interpolation calculation unit for the post-drive state data of the previous frame other than the first data. Have
Further, the display drive data generation unit selects the singular point interpolation calculation unit or the normal point interpolation calculation unit according to whether or not the post-drive state data of the previous frame is the first data. Display device control circuit.

(Appendix 5) In Appendix 4,
And a frame memory for storing the post-drive state data. The frame memory stores a flag indicating whether or not the post-drive state data is the first data. A control circuit for a liquid crystal display device, wherein a singular point interpolation calculation unit or a normal point interpolation calculation unit is selected.

(Appendix 6) In Appendix 4,
The singular point interpolation calculation unit performs nonlinear interpolation calculation on the post-drive state data of the previous frame, and the normal point interpolation calculation unit performs linear interpolation calculation on the post-drive state data of the previous frame. Control circuit for liquid crystal display devices.

(Appendix 7) In Appendix 4,
The conversion table includes a singular point conversion table when the post-drive state data of the previous frame is the second data, and a normal point conversion table for the post-drive state data of the previous frame other than the second data. ,
Further, the display drive data generation unit selects the singular point conversion table or the normal point conversion table according to whether or not the post-drive state data of the previous frame is the second data. Control circuit.

(Supplementary Note 8) In the control circuit of the liquid crystal display device,
A display drive data generation unit that generates display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame;
The display drive data generation unit
Having a conversion table for storing compensation data or compensation display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame;
The conversion table includes a first conversion table corresponding to the first frame frequency and a second conversion table corresponding to the second frame frequency,
The display drive data generation unit interpolates the compensation data or the compensation display drive data read from the first and second conversion tables by performing an interpolation operation (including an extrapolation operation) according to a current frame frequency. A control circuit for a liquid crystal display device, comprising an interpolation calculation unit for generating compensation data or interpolation compensation display drive data.

(Appendix 9) In Appendix 8,
Furthermore, the control circuit of the liquid crystal display device which has a frame frequency detection part which detects the present frame frequency.

4b1: first compensation value conversion table, 4b2: second compensation value lead tube table 4d: interpolation calculator, 10: upper bit, 12: lower bit,
nFi: Current frame image data, nFp: Post drive status data,
nFo: Display drive data

Claims (5)

In the control circuit of the liquid crystal display device,
A display drive data generation unit that generates display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame;
The display drive data generation unit
A conversion table for storing compensation data or compensation display drive data corresponding to a combination of higher-order bits of image data of the current frame and post-drive state data of the previous frame;
The compensation data or compensation display drive data read from the conversion table is interpolated according to the lower-order bits of the current frame image data and the post-drive state data of the previous frame, and the interpolation compensation data or the interpolation compensation display drive data. An interpolation calculation unit for generating
The conversion table includes a singular point conversion table when the post-drive state data of the previous frame is the first data, and a normal point conversion table for the post-drive state data of the previous frame other than the first data. ,
Further, the display drive data generation unit selects the singular point conversion table or the normal point conversion table according to whether or not the post-drive state data of the previous frame is the first data. Control circuit. In claim 1,
From the singularity conversion table, two adjacent compensation data or compensation display drive data corresponding to the upper bits of the image data of the current frame are read out, and an interpolation operation is performed according to the lower bits of the image data of the current frame. Is done,
From the normal point conversion table, four adjacent compensation data or compensation display drive data corresponding to the post-drive state data of the previous frame and the upper bits of the image data of the current frame are read, and the drive of the previous frame is read. A control circuit for a liquid crystal display device, wherein an interpolation operation is performed in accordance with the lower state bits of the rear state data and the image data of the current frame. In the control circuit of the liquid crystal display device,
A display drive data generation unit that generates display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame;
The display drive data generation unit
A conversion table for storing compensation data or compensation display drive data corresponding to a combination of higher-order bits of image data of the current frame and post-drive state data of the previous frame;
The compensation data or compensation display drive data read from the conversion table is interpolated according to the lower-order bits of the current frame image data and the post-drive state data of the previous frame, and the interpolation compensation data or the interpolation compensation display drive data. An interpolation calculation unit for generating
The interpolation calculation unit includes a singular point interpolation calculation unit when the post-drive state data of the previous frame is the first data, and a normal point interpolation calculation unit for the post-drive state data of the previous frame other than the first data. Have
Further, the display drive data generation unit selects the singular point interpolation calculation unit or the normal point interpolation calculation unit according to whether or not the post-drive state data of the previous frame is the first data. Display device control circuit. In claim 3,
The conversion table includes a singular point conversion table when the post-drive state data of the previous frame is the second data, and a normal point conversion table for the post-drive state data of the previous frame other than the second data. ,
Further, the display drive data generation unit selects the singular point conversion table or the normal point conversion table according to whether or not the post-drive state data of the previous frame is the second data. Control circuit. In the control circuit of the liquid crystal display device,
A display drive data generation unit that generates display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame;
The display drive data generation unit
Having a conversion table for storing compensation data or compensation display drive data corresponding to a combination of image data of the current frame and post-drive state data of the previous frame;
The conversion table includes a first conversion table corresponding to the first frame frequency and a second conversion table corresponding to the second frame frequency,
The display drive data generation unit interpolates the compensation data or the compensation display drive data read from the first and second conversion tables by performing an interpolation operation (including an extrapolation operation) according to a current frame frequency. A control circuit for a liquid crystal display device, comprising an interpolation calculation unit for generating compensation data or interpolation compensation display drive data.

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