WO2013051490A1

WO2013051490A1 - Display control circuit, liquid crystal display device comprising display control circuit, and display control method

Info

Publication number: WO2013051490A1
Application number: PCT/JP2012/075311
Authority: WO
Inventors: 衛大橋
Original assignee: シャープ株式会社
Priority date: 2011-10-06
Filing date: 2012-10-01
Publication date: 2013-04-11

Abstract

Provided is a display control circuit with which it is possible to display high image quality motion video inexpensively. An overdrive drive unit (122) comprises a write gradation selection unit (21) and a write gradation interpolation processing unit (22). The write gradation selection unit (21) acquires a first write gradation value and outputs first write gradation data (RDa) from SDRAM (160) when a combination of a prior frame gradation value and a current frame gradation value is present in an OS table (LUT1) and supplies the prior frame gradation value and/or the current frame gradation value which is/are nearest to the combination and the first write gradation value to the write gradation interpolation processing unit (22) when the combination is not present in the OS table (LUT1). The write gradation interpolation processing unit (22) converts the received gradation value to a voltage value, carries out a linear interpolation process using the voltage value, converts the obtained voltage value to a second write gradation value, and outputs second write gradation data (RDb).

Description

Display control circuit, liquid crystal display device including the same, and display control method

The present invention relates to a display control circuit for controlling display on a liquid crystal display panel based on an image signal given from the outside, a liquid crystal display device including the display control circuit, and a display control method. The present invention relates to a display control circuit for performing overdrive driving that emphasizes a temporal change of a signal, a liquid crystal display device including the display control circuit, and a display control method.

In recent years, there has been a strong demand for weight reduction and thinning of displays such as personal computers and televisions, and therefore liquid crystal display devices that are easy to be lightened and thinned are rapidly being adopted for such displays. However, since the response speed of the liquid crystal is slow, sufficient image quality may not be obtained when displaying a moving image on the liquid crystal display device. Therefore, in order to suppress the deterioration of the image quality at the time of moving image display due to the low response speed of the liquid crystal, a driving method called overdrive driving (or overshoot driving) has been conventionally employed. The overdrive drive is a gradation voltage higher than the gradation voltage corresponding to the input image signal of the current frame or the input of the current frame according to the combination of the input image signal of the previous frame and the input image signal of the current frame. In this driving method, a gradation voltage lower than the gradation voltage corresponding to the image signal is supplied to the liquid crystal display panel. By adopting such overdrive driving, the time required to reach the luminance corresponding to the gradation voltage in the liquid crystal display panel is shortened, so that the deterioration in image quality when displaying a moving image is suppressed.

In a liquid crystal display device adopting overdrive driving, a gradation value corresponding to an input image signal one frame before (hereinafter referred to as “previous frame gradation value”) and a gradation value corresponding to an input image signal of the current frame (hereinafter referred to as “following frame gradation value”) Lookup for overdrive drive so that the gradation voltage to be supplied to the liquid crystal display panel (hereinafter referred to as “write gradation voltage”) is determined based on the combination with “current frame gradation value”) A table (hereinafter referred to as “OS table”) is held. FIG. 15 is a diagram schematically showing an example of an OS table held in a conventional liquid crystal display device. Here, 256 gradation display is performed. In FIG. 15, the numerical value indicated in the leftmost column indicates the previous frame gradation value, and the numerical value indicated in the uppermost line indicates the current frame gradation value. The numerical value written at the position where each row intersects with each column corresponds to the writing gradation voltage determined based on the combination of each previous frame gradation value and each current frame gradation value. A gradation value (hereinafter referred to as “writing gradation value”) is shown. For example, when the previous frame gradation value is “64” and the current frame gradation value is “128”, the writing gradation value is “166”. For example, when the previous frame gradation value is “160” and the current frame gradation value is “64”, the writing gradation value is “4”. As described above, based on the data stored in the OS table, the writing gradation voltage higher than the gradation voltage corresponding to the current frame gradation value or the gradation voltage corresponding to the current frame gradation value. A low writing gradation voltage is applied to the liquid crystal.

Incidentally, in recent years, development of a liquid crystal display device capable of displaying an image in two display modes of two-dimensional display (hereinafter referred to as “2D display”) and three-dimensional display (hereinafter referred to as “3D display”) is remarkable. In 3D display on such a liquid crystal display device, even if the display image is a still image, the liquid crystal is driven in the same way as when displaying a moving image so that parallax occurs between the viewer's left eye and right eye. Is done. For this reason, during 3D display, overdrive driving is performed even if the display image is a still image. As described above, overdrive driving plays an important role particularly in a liquid crystal display device capable of displaying an image in two display modes of 2D display and 3D display. The following “moving image display” in this specification includes still image display during 3D display.

Regarding the liquid crystal display device that employs overdrive driving, the invention disclosed in Patent Document 1 prepares a plurality of types of OS tables and responds to the difference in gradation value between two consecutive frames in 3D display. The OS table to be used is selected, and the writing gradation value is determined based on the selected OS table. Thereby, the image quality in 3D display can be improved.

By the way, generally, in order to reduce the memory capacity and reduce the cost, the OS table includes the number of gradations × the number of gradations (for example, 256 gradations × 256 gradations in the case of 256 gradation display). Minute data is not stored, and data smaller than this, for example, data of 16 gradations × 16 gradations is stored. For this reason, the combination of the previous frame gradation value and the current frame gradation value may not exist in the OS table. In such a case, conventionally, by using a combination of the previous frame gradation value and the current frame gradation value existing in the OS table, interpolation based on the gradation value (typically linear interpolation) is performed. The writing gradation value was determined.

Japanese Unexamined Patent Publication No. 2011-90079

However, from the VT (Voltage-Transmittance) characteristic of the liquid crystal, the gradation value and the gradation voltage are not in a linear relationship. Furthermore, the response speed of the liquid crystal depends on the gradation voltage (writing gradation voltage). For this reason, even if the writing gradation value is determined by interpolation based on the gradation value as described above when the combination of the previous frame gradation value and the current frame gradation value does not exist in the OS table, this writing A desired writing gradation voltage cannot be obtained from the embedded gradation value, and as a result, an appropriate liquid crystal response speed cannot be obtained. Therefore, it is not possible to sufficiently suppress image quality degradation when displaying moving images. The same applies to the invention disclosed in Patent Document 1.

Therefore, an object of the present invention is to provide a display control circuit that enables high-quality moving image display at low cost, a liquid crystal display device including the display control circuit, and a display control method.

A first aspect of the present invention is a display control circuit for controlling display on a liquid crystal display panel based on an image signal given from the outside,
A writing gradation value used for correction for emphasizing a temporal change of the signal with respect to the image signal is given in the previous frame gradation value which is a gradation value in a frame immediately before the current frame, and in the current frame. A storage unit storing a first look-up table for determination based on a combination of current frame gradation values which are gradation values of the image signal;
The first look-up table is referred to, and when the combination exists in the first look-up table, the writing gradation value determined based on the combination is output, and the combination is the first look-up table. If not present in one lookup table, the previous frame tone value and / or the current frame tone value corresponding to the combination closest to the combination and present in the first lookup table And a first gradation selection unit that outputs at least the write gradation value;
When the combination does not exist in the first lookup table, the previous frame gradation value and / or the current frame gradation value and the writing gradation value output from the first gradation selection unit Are converted into voltage values, and interpolation processing for obtaining the writing gradation values corresponding to the combinations not existing in the first look-up table is performed using the voltage values. And an interpolation unit.

According to a second aspect of the present invention, in the first aspect of the present invention,
The interpolation process performed by the first interpolation unit is a linear interpolation process.

According to a third aspect of the present invention, in the second aspect of the present invention,
The first gradation selection unit is closest to the previous frame gradation value when only the previous frame gradation value is not present in the first lookup table in the combination, and The previous frame gradation value existing in the first look-up table and the writing gradation value determined based on a combination of the previous frame gradation value and the current frame gradation value are output. It is characterized by that.

According to a fourth aspect of the present invention, in the second aspect of the present invention,
When only the current frame gradation value does not exist in the first lookup table, the first gradation selection unit is closest to the current frame gradation value, and And outputting the current frame gradation value existing in the first look-up table and the writing gradation value determined based on a combination of the current frame gradation value and the previous frame gradation value. It is characterized by that.

According to a fifth aspect of the present invention, in the second aspect of the present invention,
When the previous frame gradation value and the current frame gradation value constituting the combination do not exist in the first lookup table, the first gradation selection unit The previous frame tone value, the current frame tone value, the previous frame tone value, and the current frame that are closest to the current frame tone value and exist in the first lookup table. The writing gradation value determined based on a combination of gradation values is output.

According to a sixth aspect of the present invention, in the first aspect of the present invention,
The previous frame gradation value is the current frame gradation value in a frame immediately before the current frame.

According to a seventh aspect of the present invention, in the first aspect of the present invention,
The storage unit further includes a second lookup table for determining a reached gradation value, which is a gradation value predicted to be reached in the display on the liquid crystal display panel, based on the combination,
When the second lookup table is referred to and the combination exists in the second lookup table, the reached gradation value is set as the previous frame gradation value in the frame immediately after the current frame. , If the combination does not exist in the second lookup table, the previous frame tone value that is closest to the combination and that corresponds to the combination present in the second lookup table and / or A second gradation selection unit that outputs at least the current frame gradation value and the reached gradation value;
When the combination does not exist in the second look-up table, based on the previous frame gradation value and / or the current frame gradation value and the reached gradation value output from the second selection unit. Then, the reached gradation value obtained by performing interpolation processing in a predetermined format for acquiring the reached gradation value corresponding to the combination that does not exist in the second lookup table is immediately after the current frame. And a second interpolating unit for setting the previous frame gradation value in the previous frame.

According to an eighth aspect of the present invention, in the seventh aspect of the present invention,
The second interpolation unit converts each of the previous frame tone value and / or the current frame tone value and the reached tone value output from the second selection unit into a voltage value, and The interpolation process for acquiring the reached gradation value corresponding to the combination that does not exist in the second look-up table is performed using a voltage value.

A ninth aspect of the present invention is the eighth aspect of the present invention,
The interpolation process performed by the second interpolation unit is a linear interpolation process.

According to a tenth aspect of the present invention, in a ninth aspect of the present invention,
When only the previous frame gradation value does not exist in the second lookup table in the combination, the second gradation selection unit is closest to the previous frame gradation value, and Outputting the previous frame gradation value existing in the second look-up table and the reached gradation value determined based on a combination of the previous frame gradation value and the current frame gradation value. It is characterized by.

An eleventh aspect of the present invention is the ninth aspect of the present invention,
When only the current frame tone value does not exist in the second look-up table in the combination, the second tone selecting unit is closest to the current frame tone value, and Outputting the current frame gradation value existing in the second look-up table and the reached gradation value determined based on a combination of the current frame gradation value and the previous frame gradation value. It is characterized by.

A twelfth aspect of the present invention is the ninth aspect of the present invention,
The second gradation selection unit, when the previous frame gradation value and the current frame gradation value constituting the combination do not exist in the second lookup table, The previous frame gradation value, the current frame gradation value, the previous frame gradation value, and the current frame that are closest to the current frame gradation value and exist in the second lookup table. The reached gradation value determined based on a combination of gradation values is output.

A thirteenth aspect of the present invention is a liquid crystal display device,
A display control circuit according to any of the first to twelfth aspects of the present invention;
And a liquid crystal display panel for performing display based on the writing gradation value obtained by the display control circuit.

A fourteenth aspect of the present invention is a display control method for controlling display on a liquid crystal display panel based on an image signal given from the outside,
A writing gradation value used for correction for emphasizing a temporal change of the signal with respect to the image signal is given in the previous frame gradation value which is a gradation value in a frame immediately before the current frame, and in the current frame. Referring to a first lookup table for determining based on a combination of current frame tone values that are tone values of the image signal;
Outputting the writing gradation value determined based on the first combination when the combination exists in the first lookup table;
If the combination does not exist in the first lookup table, the previous frame tone value and / or the current value that is closest to the combination and that corresponds to the combination that exists in the first lookup table. Outputting at least a frame gradation value and the writing gradation value;
Converting each of the previous frame gradation value and / or the current frame gradation value and the writing gradation value output when the combination does not exist in the first lookup table into a voltage value; Performing interpolation processing for obtaining the writing gradation value corresponding to the combination that does not exist in the first lookup table using the voltage value.

According to the first aspect of the present invention, when there is no combination in the first look-up table, the first interpolation unit performs the writing gradation value, the previous frame gradation value, and the current frame gradation value. Are converted into voltage values, and interpolation processing is performed to acquire writing gradation values corresponding to combinations that do not exist in the first lookup table using the voltage values. Since the response speed of the liquid crystal depends on the voltage value (that is, the gradation voltage), the interpolation process using the gradation voltage is performed according to the VT characteristic of the liquid crystal when no combination exists in the first lookup table. Overdrive driving (driving for correcting the temporal change of the signal with respect to the image signal) can be performed using the gradation voltage. Therefore, a more appropriate liquid crystal response speed can be obtained as compared with the conventional technique in which overdrive driving is performed using the first look-up table having a relatively small memory capacity. Thereby, high-quality moving image display can be performed at low cost.

According to the second aspect of the present invention, the linear interpolation process is used as the interpolation process in the first interpolation unit, so that the same effect as that of the first aspect of the present invention can be achieved with a simple process.

According to the third aspect of the present invention, when only the previous frame gradation value does not exist in the first look-up table among the combinations, the first frame closest to the previous frame gradation value and the first By using the previous frame gradation value existing in the look-up table and the writing gradation value determined based on the combination of the previous frame gradation value and the current frame gradation value, The same effects as in the above aspect can be obtained.

According to the fourth aspect of the present invention, when only the current frame gradation value does not exist in the first lookup table among the combinations, the value is closest to the current frame gradation value, and the first By using the current frame gradation value existing in the lookup table and the writing gradation value determined based on the combination of the current frame gradation value and the previous frame gradation value, The same effects as in the above aspect can be obtained.

According to the fifth aspect of the present invention, when the previous frame gradation value and the current frame gradation value forming the combination are not present in the first lookup table, the previous frame gradation value and the current frame gradation value are determined. Based on the combination of the previous frame tone value and the current frame tone value, and the previous frame tone value and the current frame tone value that are closest to the tone value and exist in the first lookup table. By using the writing gradation value determined in this manner, the same effect as in the second aspect of the present invention can be obtained.

According to the sixth aspect of the present invention, the same effect as in the first aspect of the present invention can be obtained by using the current frame gradation value in the frame immediately before the current frame as the previous frame gradation value. it can.

According to the seventh aspect of the present invention, the reached gradation value obtained by using the second lookup table in the previous frame is referred to as the previous frame gradation value in the current frame. Used. For this reason, it is possible to perform overdrive driving using a more accurate previous frame gradation value. As a result, the response speed of the liquid crystal is corrected more appropriately, so that the image quality of moving image display can be further improved.

According to the eighth aspect of the present invention, the interpolation process when the combination does not exist in the second lookup table is performed by using the voltage value (that is, the gradation voltage). For this reason, the interpolation process is performed in consideration of the VT characteristics of the liquid crystal, so that a more accurate reached gradation value can be obtained. Since the reached gradation value obtained in this way is used for overdrive driving as the previous frame gradation value, the response speed of the liquid crystal is corrected more appropriately. Thereby, the image quality of moving image display can be further improved.

According to the ninth aspect of the present invention, the linear interpolation process is used as the interpolation process in the second interpolation processing unit, so that the same effects as those of the eighth aspect of the present invention can be achieved with a simple process.

According to the tenth aspect of the present invention, when only the previous frame gradation value does not exist in the second lookup table among the combinations, the value is closest to the previous frame gradation value, and the second By using the input tone value existing in the look-up table and the reached tone value determined based on the combination of the previous frame tone value and the current frame tone value, The same effects as in the above aspect can be obtained.

According to the eleventh aspect of the present invention, when only the current frame gradation value does not exist in the second lookup table among the combinations, the value is closest to the current frame gradation value, and the second By using the current frame tone value existing in the look-up table and the reached tone value determined based on the combination of the current frame tone value and the previous frame tone value, The same effect as the aspect can be achieved.

According to the twelfth aspect of the present invention, when the previous frame gradation value and the current frame gradation value constituting the combination do not exist in the second lookup table, the previous frame gradation value and the current frame A combination of the previous frame gradation value and the current frame gradation value, and the combination of the previous frame gradation value and the current frame gradation value that is closest to the gradation value and exists in the second lookup table. By using the reached gradation value determined based on this, the same effect as that of the ninth aspect of the present invention can be obtained.

According to the thirteenth aspect of the present invention, the liquid crystal display device can achieve the same effects as any of the first to twelfth aspects of the present invention.

According to the fourteenth aspect of the present invention, the display control method can achieve the same effects as those of the first aspect of the present invention.

1 is a block diagram illustrating an overall configuration of a liquid crystal display device according to a first embodiment of the present invention. It is a block diagram for demonstrating the function structure of the timing controller IC in the said 1st Embodiment. It is a block diagram for demonstrating the detailed functional structure of the overdrive drive part in the said 1st Embodiment. It is the figure which showed typically an example of the OS table in the said 1st Embodiment. It is the figure which showed typically a part of OS table (or prediction table) in order to demonstrate the interpolation process in the 1st case in the 1st or 2nd embodiment of this invention. FIG. 6 is a diagram schematically showing gradation value-gradation voltage characteristics in order to explain how the error voltage is eliminated in the first case in the first embodiment. It is the figure which showed typically a part of OS table (or prediction table), in order to demonstrate the interpolation process in the 2nd case in the said 1st or 2nd embodiment. FIG. 6 is a diagram schematically showing gradation value-gradation voltage characteristics in order to explain how the error voltage is eliminated in the second case in the first embodiment. It is the figure which showed typically a part of OS table (or prediction table), in order to demonstrate the interpolation process in the 3rd case in the said 1st or 2nd embodiment. FIG. 10 is a diagram schematically showing gradation value-gradation voltage characteristics in order to explain how the error voltage is eliminated in the third case in the first embodiment. It is a block diagram for demonstrating the detailed functional structure of the overdrive drive part in the said 2nd Embodiment. It is the figure which showed typically an example of the prediction table in the said 2nd Embodiment. It is the figure which showed typically an example of the OS table in the said 2nd Embodiment. It is a block diagram for demonstrating the detailed functional structure of the overdrive drive part in the said 3rd Embodiment. It is the figure which showed typically an example of the OS table currently hold | maintained at the conventional liquid crystal display device. FIG. 6 is a diagram schematically illustrating an example of an OS table in order to explain a case where a combination of a previous frame gradation value and a current frame gradation value does not exist in the OS table in the basic study of the present invention. FIG. 6 is a diagram schematically showing gradation value-gradation voltage characteristics in order to explain a case where the combination of the previous frame gradation value and the current frame gradation value does not exist in the OS table in the basic study.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an embodiment of the present invention, a basic study made by the present inventor to solve the above problems will be described. In the basic examination of the present invention and the liquid crystal display device in each embodiment described later, display with 256 gradations is performed. Further, in this specification, “the combination of the previous frame gradation value and the current frame gradation value does not exist in the lookup table (OS table and prediction table)” means that the previous frame gradation value is in the lookup table. This means that only the current frame gradation value does not exist in the lookup table, or that both the previous frame gradation value and the previous frame gradation value do not exist in the lookup table. Also, “close to the combination of the previous frame gradation value and the current frame gradation value” means that the value is close to the previous frame gradation value related to the combination, and the current frame gradation value related to the combination has a value. It means that the value is close or the value is close to the writing gradation value (or the reached gradation value) related to the combination.

<0. Basic study>
In the basic study of the present invention, the case where the combination of the previous frame gradation value and the current frame gradation value does not exist in the OS table in the conventional liquid crystal display device will be considered. FIG. 16 is a diagram schematically showing an example of the OS table in order to explain a case where the combination of the previous frame gradation value and the current frame gradation value does not exist in the OS table in this basic study. Here, it is assumed that the previous frame gradation value and the current frame gradation value used for referring to the OS table are Gxc and Gya, respectively, and the previous frame gradation value Gxc does not exist in the OS table. In this case, in the conventional liquid crystal display device, the writing gradation value (Gca) corresponding to the combination of the previous frame gradation value Gxc and the current frame gradation value Gya is obtained by interpolation (typically linear interpolation). Desired. Specifically, the previous frame gradation value Gxa and Gxb in the vicinity of the previous frame gradation value Gxc, the writing gradation value Gaa corresponding to the combination of the previous frame gradation value Gxa and the current frame gradation value Gya, By performing linear interpolation on the write tone values Gaa and Gba using the write tone value Gba corresponding to the combination of the previous frame tone value Gxb and the current frame tone value Gya, the write tone value Gca Is required. The writing gradation value Gca thus obtained is converted into a writing gradation voltage and applied to the liquid crystal.

FIG. 17 schematically shows the gradation value-gradation voltage characteristics in order to explain the case where the combination of the previous frame gradation value and the current frame gradation value does not exist in the OS table in this basic study. FIG. This gradation value-gradation voltage characteristic is determined based on the VT characteristic of the liquid crystal as described above. As shown in FIG. 17, the gradation value and the gradation voltage are not in a linear relationship. More specifically, the change in the gradation voltage with respect to the change in the gradation value is large near the low gradation value and the vicinity of the high gradation value, and the change in the gradation voltage with respect to the change in the gradation value is extremely small near the middle gradation value.

The writing gradation value Gca obtained by linear interpolation is the center value of the writing gradation values Gaa and Gba. However, since the gradation value and the gradation voltage are not in a linear relationship as described above, the writing gradation voltage Vca corresponding to the writing gradation value Gca is equal to the writing gradation as shown in FIG. This is not the median value of the write gradation voltage Vaa corresponding to the value Gaa and the write gradation voltage Vba corresponding to the write gradation value Gba. In this example, the gradation voltage Vba is higher than the intermediate value. The value is close to. As described above, the response speed of the liquid crystal depends on the gradation voltage. Therefore, when the combination does not exist in the OS table in overdrive driving, the writing gradation voltage Vaa corresponding to the writing gradation value Gaa and the writing are written. It is desirable to apply to the liquid crystal a writing gradation voltage (hereinafter referred to as “ideal writing voltage”, which is represented by the symbol Vid) corresponding to the center value of the writing gradation voltage Vba corresponding to the gradation value Gba. . Since the writing gradation voltage Vca shown in FIG. 17 is higher than the ideal writing voltage Vid, if the liquid crystal display panel is in the normally black mode, the writing gradation voltage Vca is applied to the liquid crystal. When applied, the display becomes brighter than expected. Thus, the error voltage (“the writing gradation voltage corresponding to the writing gradation value obtained by linear interpolation based on the gradation value and the ideal writing voltage Vid” is applied to the writing gradation voltage to be applied to the liquid crystal. If a difference between the liquid crystal and the liquid crystal is generated, an appropriate liquid crystal response speed cannot be obtained. As a result, the conventional liquid crystal display device cannot sufficiently suppress deterioration in image quality when displaying moving images.

The first to third embodiments of the present invention made by the inventors of the present application based on the above basic examination will be described below with reference to the accompanying drawings.

<1. First Embodiment>
The first embodiment of the present invention relates to a liquid crystal display device that performs overdrive driving using an OS table.

<1.1 Overall configuration and operation overview>
FIG. 1 is a block diagram showing the overall configuration of the liquid crystal display device according to the present embodiment. This liquid crystal display device includes a liquid crystal display panel 5 including a display unit 500, a control substrate 10, a source driver 300, and a gate driver 400. On the control board 10, a timing controller IC 100 as a display control circuit and a flash memory 200 as a nonvolatile memory are mounted. Note that both or one of the source driver 300 and the gate driver 400 may be included in the liquid crystal display panel 5. That is, both or one of the source driver 300 and the gate driver 400 may be monolithically formed on the glass substrate that constitutes the liquid crystal display panel 5.

In the liquid crystal display device according to the present embodiment, two display modes of 2D display and 3D display are prepared, and the display unit 500 of the liquid crystal display panel 5 displays an image in 2D display or 3D display depending on the display mode. It is possible. Hereinafter, a display mode in which 2D display is to be performed is referred to as “2D mode”, and a display mode in which 3D display is to be performed is referred to as “3D mode”. Note that it is not essential for the present invention to prepare two display modes of the 2D mode and the 3D mode, and only the 2D mode or only the 3D mode may be prepared.

In the display unit 500, a plurality of source lines SL, a plurality of gate lines GL, and pixel forming portions provided corresponding to the intersections of the source lines SL and the gate lines GL are formed. That is, the display unit 500 includes a plurality of pixel formation units. The plurality of pixel forming portions are arranged in a matrix to form a pixel array. Each pixel forming portion includes a thin film transistor 50 which is a switching element having a gate terminal connected to a gate line passing through a corresponding intersection and a source terminal connected to a source line passing through the intersection, and a drain terminal of the thin film transistor 50 A pixel electrode 51 connected to the common electrode 52, a common electrode 52 which is a common electrode provided in the plurality of pixel formation portions, and a common electrode 52 provided in the plurality of pixel formation portions. The liquid crystal layer is sandwiched between the common electrode 52. A pixel capacitor Cp is constituted by a liquid crystal capacitor formed by the pixel electrode 51 and the common electrode 52. Normally, an auxiliary capacitor is provided in parallel with the liquid crystal capacitor in order to reliably hold the voltage in the pixel capacitor Cp. However, since the auxiliary capacitor is not directly related to the present invention, its description and illustration are omitted. Note that only the components corresponding to one pixel formation portion are shown in the display portion 500 of FIG.

The timing controller IC 100 receives an image signal DAT, a timing signal TS such as a horizontal synchronization signal and a vertical synchronization signal, and a mode signal MD indicating a display mode from the outside, and performs a predetermined correction process on the image signal DAT. The digital video signal DV, the source start pulse signal SSP for controlling the operation of the source driver 300, the source clock signal SCK, and the latch strobe signal LS, the gate start pulse signal GSP for controlling the operation of the gate driver 400, and A gate clock signal GCK is output. Note that immediately after the power is turned on or when the display mode is switched, the timing controller IC 100 reads data necessary for the correction processing from the flash memory 200 and writes the read data to the internal volatile memory.

The source driver 300 receives the digital video signal DV, the source start pulse signal SSP, the source clock signal SCK, and the latch strobe signal LS output from the timing controller IC 100, and applies a driving video signal to each source line SL. At this time, the source driver 300 sequentially holds the digital video signal DV indicating the voltage (write gradation value) to be applied to each source line SL at the timing when the pulse of the source clock signal SCK is generated. The held digital video signal DV is converted into an analog voltage (write gradation voltage) at the timing when the pulse of the latch strobe signal LS is generated. The converted analog voltage is simultaneously applied to all the source lines SL as a driving video signal.

The gate driver 400 repeats the application of the active scanning signal to each gate line GL with one frame period as a cycle based on the gate start pulse GSP and the gate clock signal GCK output from the timing controller IC100.

As described above, when the driving video signal is applied to each source line SL and the active scanning signal is applied to each gate line GL, an image based on the image signal DAT transmitted from the outside is displayed on the liquid crystal display panel. 5 on the display unit 500.

<1.2 Configuration of timing controller IC>
FIG. 2 is a block diagram for explaining a functional configuration of the timing controller IC 100 in the present embodiment. The timing controller IC 100 includes a data reception unit 110, a data processing unit 120, a line buffer 130, a data transmission unit 140, a timing control unit 150, an SDRAM 160 as a storage unit, and an SDRAM interface unit 170. The data processing unit 120 includes a gamma correction unit 121 and an overdrive drive unit 122.

The data receiving unit 110 receives an image signal DAT transmitted from the outside and gives it to the data processing unit 120.

The gamma correction unit 121 in the data processing unit 120 performs gamma correction according to the characteristics of the liquid crystal display panel 5 used. Since this gamma correction is well known to those skilled in the art, description thereof is omitted. Various known gamma corrections can be used as the gamma correction in the present embodiment.

The overdrive drive unit 122 in the data processing unit 120 performs correction for emphasizing the temporal change of the signal with respect to the image signal DAT on which gamma correction has been performed, and displays the writing gradation value in each pixel forming unit. The gray level data WD is generated and output to the line buffer 130. The overdrive drive unit 122 is given a mode signal MD indicating whether the display mode is the 2D mode or the 3D mode, and the overdrive drive unit 122 performs processing according to the display mode.

FIG. 3 is a block diagram for explaining a detailed configuration of the overdrive driving unit 122 in the present embodiment. As shown in FIG. 3, the overdrive driving unit 122 includes a writing tone selection unit 21 and a writing tone interpolation processing unit 22 as a first interpolation unit. The writing gradation interpolation processing unit 22 includes a gradation value-voltage conversion unit 23, an interpolation calculation unit 24, and a voltage-gradation value conversion unit 25. The writing gradation selection unit 21 inputs the current frame gradation value indicated by the input data (hereinafter referred to as “current frame data”) CD of the current frame to the writing gradation selection unit 21 and one frame before the current frame data. 4, based on the previous frame gradation value indicated by PD (hereinafter referred to as “previous frame data”) PD, for example, the writing gradation value is determined by referring to the OS table LUT1 shown in FIG. The gray scale data WD is output. The OS table LUT1 corresponds to a first lookup table. Here, in order to reduce the memory capacity, data for 16 gradations × 16 gradations is prepared in the OS table LUT1. In FIG. 4 (the same applies to FIG. 12 to be described later), the numerical value indicated in the leftmost column indicates the previous frame gradation value, and the numerical value indicated in the uppermost line indicates the current frame gradation value. Show. A numerical value written at a position where each row and each column intersect indicates a writing gradation value determined based on a combination of each previous frame gradation value and each current frame gradation value. . However, when the combination of the previous frame gradation value and the current frame gradation value does not exist in the OS table LUT1, the writing gradation selection unit 21 is at least the previous frame gradation value and / or the closest to the combination. Alternatively, the current frame gradation value and the written gradation value are given to the gradation value-voltage conversion unit 23. The gradation value-voltage conversion unit 23 converts each received gradation value into a voltage value and outputs it. The interpolation calculation unit 24 uses the converted voltage value output from the gradation value-voltage conversion unit 23 to obtain a linear interpolation process for acquiring a writing gradation value corresponding to a combination that does not exist in the OS table LUT1. The voltage value obtained by the interpolation process is output. The voltage-gradation value conversion unit 25 converts the voltage value output from the interpolation calculation unit 24 into a gradation value (writing gradation value), and outputs writing gradation data WD indicating the converted gradation value. Hereinafter, the writing gradation data WD output from the writing gradation selection unit 21 is referred to as “first writing gradation data”, and is represented by a symbol WDa. The writing gradation data WD output from the voltage-gradation value conversion unit 25 is referred to as “second writing gradation data” and is denoted by reference numeral WDb. Further, the writing gradation value indicated by the first writing gradation data WDa is referred to as “first writing gradation value”, and the writing gradation value indicated by the second writing gradation data WDb. This is called “second writing gradation value”.

In the line buffer 130, the writing gradation data WD for one line output from the overdrive driving unit 122 is held.

The data transmission unit 140 takes out the write gradation data WD from the line buffer 130 and outputs it as a digital video signal DV.

The timing control unit 150 controls operations of the data reception unit 110, the data processing unit 120, and the data transmission unit 140 based on a timing signal TS transmitted from the outside, and also includes a source start pulse signal SSP, a source clock signal SCK, A latch strobe signal LS, a gate start pulse GSP, and a gate clock signal GCK are output.

SDRAM 160 is a volatile memory. The SDRAM 160 stores data used for processing by the overdrive drive unit 122 (hereinafter referred to as “overdrive drive data”). The overdrive driving data is composed of the previous frame data PD and the OS table LUT1.

The SDRAM interface unit 170 functions as an interface between the data processing unit 120 and the SDRAM 160 when writing data to the SDRAM 160 and reading data from the SDRAM 160.

The flash memory 200 is also mounted on the control board 10 on which the timing controller IC 100 is mounted. The flash memory 200 stores at least an OS table LUT1 which is a part of overdrive driving data. Since the flash memory 200 is non-volatile, the contents of the OS table LUT1 will not be lost even when the power of the apparatus is turned off. The timing controller IC 100 reads the OS table LUT1 from the flash memory 200 and writes it to the internal SDRAM 160 immediately after the device is turned on. Thus, by adopting a configuration in which the OS table LUT1 is written in the flash memory 200 instead of the timing controller IC 100, the contents of the OS table LUT1 can be rewritten from the outside relatively easily.

<1.3 Operation>
Next, the operation of the overdrive drive unit 122 in this embodiment will be described. Note that the overdrive drive unit 122 actually performs an operation according to the display mode, such as changing an OS table to be referred to according to the display mode, but the operation unique to the present invention is performed in the 2D mode and the 3D mode. It is common. For this reason, the operation described below is performed in, for example, the 3D mode, and the operation description for each display mode is omitted. The writing gradation selection unit 21 receives the current frame data CD, and further reads the previous frame data PD stored in the SDRAM 160. At this time, the current frame data CD received by the writing gradation selection unit 21 is stored in the SDRAM 160 as the previous frame data PD in the frame next to the current frame. Then, the writing gradation selection unit 21 refers to the OS table LUT1 stored in the SDRAM 160 based on the previous frame gradation value indicated by the previous frame data PD and the current frame gradation value indicated by the current frame data CD. Thereafter, in the present embodiment, the combination of the previous frame gradation value and the current frame gradation value exists in the OS table LUT1 (hereinafter sometimes simply referred to as “there is a combination”) and does not exist (hereinafter referred to as “there is a combination”). The operations are different from each other simply by “when there is no combination”.

<1.3.1 Operation when a combination exists>
The operation when a combination exists is performed as follows. The write tone selection unit 21 acquires from the SDRAM 160 first write tone data WDa indicating the first write tone value corresponding to the combination of the previous frame tone value and the current frame tone value. . Then, the write gradation selection unit 21 gives the first write gradation data WDa to the line buffer 130. As described above, when the combination exists, the above-described linear interpolation processing is not performed.

<1.3.2 Operation when no combination exists>
The operation when there is no combination is specifically divided into three types of operations. That is, the operation when the previous frame gradation value does not exist and the current frame gradation value exists in the OS table LUT1 (prediction table LUT2 in the third embodiment described later) (hereinafter referred to as “first case”). The operation when the previous frame gradation value exists in the OS table LUT1 and the current frame gradation value does not exist (hereinafter referred to as “second case”), the previous frame gradation value, and the current frame gradation value. There are three types when both of them are not present (hereinafter referred to as “third case”). In the following, the operation when there is no combination will be described separately for the operation of the first case, the operation of the second case, and the operation of the third case.

<1.3.2.1 Operation in First Case>
FIG. 5 is a diagram schematically showing a part of the OS table LUT1 in order to explain the operation of the first case in the present embodiment. Here, a gradation value is indicated by a code whose initial is “G”, and a gradation voltage is indicated by a code whose initial is “V”. The gradation voltage indicated in parentheses on the right side or the lower side of the gradation value is a gradation voltage obtained by converting the gradation value into a voltage value for convenience of explanation. The voltage does not exist in the OS table LUT1 (the same applies to FIGS. 7 and 9 described later). As shown in FIG. 5, in the OS table LUT1, there are written in correspondence with the previous frame gradation values Gxa and Gxb, the current frame gradation value Gya, and the combination of the previous frame gradation value Gxa and the current frame gradation value Gya. There is a built-in gradation value Gaa and a writing gradation value Gba corresponding to a combination of the previous frame gradation value Gxb and the current frame gradation value Gya. It is assumed that the previous frame gradation value Gxa is smaller than Gxb and the writing gradation value Gaa is smaller than Gba. Under such a premise, the first frame gradation value used for referring to the OS table LUT1 is Gxc that does not exist in the OS table LUT1, and the current frame gradation value is Gya that exists in the OS table LUT1. The operation will be described. The previous frame gradation value Gxc is larger than the previous frame gradation value Gxa and smaller than Gxb.

Since the writing gradation value corresponding to the combination of the previous frame gradation value Gxc and the current frame gradation value Gya does not exist in the OS table LUT1, the writing gradation selection unit 21 exists in the OS table LUT1, and Of the two previous frame gradation values closest to the previous frame gradation value Gxc, the previous frame gradation value Gxa having a value smaller than the previous frame gradation value Gxc and the current frame level existing in the OS table LUT1 The write tone value Gaa corresponding to the combination with the tone value Gya is acquired from the SDRAM 160. Similarly, the write tone selection unit 21 is present in the OS table LUT1 and is more than the previous frame tone value Gxc of the two previous frame tone values closest to the previous frame tone value Gxc. The write gradation value Gba corresponding to the combination of the previous frame gradation value Gxb having a large value and the current frame gradation value Gya existing in the OS table LUT1 is acquired from the SDRAM 160.

The writing gradation selection unit 21 acquires the previous frame gradation values Gxa and Gxb from the SDRAM 160 in addition to the writing gradation values Gaa and Gba acquired as described above. Then, the write tone selection unit 21 writes the write tone values Gaa and Gba and the previous frame tone values Gxa and Gxb acquired from the SDRAM 160, and the previous frame tone value Gxc that does not exist in the OS table LUT1. This is given to the gradation value-voltage conversion unit 23 in the gradation interpolation processing unit 22.

The gradation value-voltage conversion unit 23 converts the writing gradation values Gaa, Gba and the previous frame gradation values Gxa, Gxb, Gxc received from the writing gradation selection unit 21 into voltage values and outputs them. . In FIG. 5, the gradation voltages obtained by converting the writing gradation values Gaa and Gba and the previous frame gradation values Gxa, Gxb, and Gxc received from the writing gradation selection unit 21 into voltage values are Vaa. , Vba, Vxa, Vxb, and Vxc. Hereinafter, the gradation voltage obtained by converting the previous frame gradation value into the voltage value is referred to as “previous frame gradation voltage”.

The interpolation calculation unit 24 receives the writing gradation voltages Vaa and Vba and the previous frame gradation voltages Vxa, Vxb, and Vxc from the gradation value-voltage conversion unit 23, and performs the writing step by linear interpolation processing using them. A regulated voltage Vvca is generated and output. Here, the linear interpolation processing in the first case is performed based on the following equation (1).
Vvca = Vaa + (Vba−Vaa) × (Vxc−Vxa) / (Vxb−Vxa)
... (1)

The voltage-gradation value conversion unit 25 receives the write gradation voltage Vvca from the interpolation calculation unit 24, converts it into a gradation value (second writing gradation value), and outputs the second writing step. Second write gradation data WDb indicating a tone value is applied to the line buffer 130. As described above, the operation of the first case in the overdrive drive unit 122 is performed.

FIG. 6 is a diagram schematically showing gradation value-gradation voltage characteristics in order to explain the operation of the first case in the present embodiment. As shown in FIG. 6, in the first case, the conventional liquid crystal display device performs linear interpolation processing using the writing gradation values Gaa and Gba and the previous frame gradation values Gxa, Gxb, and Gxc, and performs the linear interpolation. The writing gradation value Gca obtained by the interpolation processing is converted into the writing gradation voltage Vgca by the source driver 300 and applied to the liquid crystal. Since the response speed of the liquid crystal depends on the gradation voltage, the writing gradation voltage Vgca obtained by the linear interpolation processing based on the gradation value in the conventional liquid crystal display device does not become the above-described ideal writing voltage Vid. For this reason, in the conventional liquid crystal display device, an error voltage is generated in the first case. On the other hand, in the first case, the liquid crystal display device according to the present embodiment has a writing scale obtained by converting the writing gradation values Gaa and Gba and the previous frame gradation values Gxa, Gxb and Gxc into voltage values, respectively. The linear interpolation processing based on the above equation (1) is performed using the adjustment voltages Vaa, Vba and the previous frame gradation voltages Vxa, Vxb, Vxc, and the writing gradation voltage Vvca obtained by the linear interpolation processing is gradation The gradation value is converted again into the writing gradation voltage Vvca in the source driver 300 and applied to the liquid crystal. In this way, since the linear interpolation process in the present embodiment is performed based on the voltage value, the write gradation voltage Vvca obtained by the linear interpolation process is a value corresponding to the ideal write voltage Vid described above.

<1.3.2.2 Operation of Second Case>
FIG. 7 is a diagram schematically showing a part of the OS table LUT1 in order to explain the operation of the second case in the present embodiment. As shown in FIG. 7, in the OS table LUT1, there are written data corresponding to combinations of the previous frame gradation value Gxa, the current frame gradation values Gya and Gyb, and the previous frame gradation value Gxa and the current frame gradation value Gya. There is a gray level value Gaa and a gray level value Gab corresponding to a combination of the previous frame gray level value Gxa and the current frame gray level value Gyb. It is assumed that the current frame gradation value Gya is smaller than Gyb and the writing gradation value Gaa is smaller than Gab. Under such a premise, in the first case, the previous frame gradation value used for referring to the OS table LUT1 is Gxa existing in the OS table LUT1, and the current frame gradation value is Gyc not existing in the OS table LUT1. The operation will be described. The current frame gradation value Gyc is larger than the current frame gradation value Gya and smaller than Gyb.

Since the writing gradation value corresponding to the combination of the previous frame gradation value Gxa and the current frame gradation value Gyc does not exist in the OS table LUT1, the writing gradation selection unit 21 performs the previous frame existing in the OS table LUT1. The current frame whose value is smaller than the current frame tone value Gyc among the two current frame tone values that are present in the OS table LUT1 and closest to the current frame tone value Gyc. The write gradation value Gaa corresponding to the combination with the gradation value Gya is acquired from the SDRAM 160. Similarly, the write tone selection unit 21 and the two previous frame tone values Gxa existing in the OS table LUT1 and two current frame steps present in the OS table LUT1 and closest to the current frame tone value Gyc. A write tone value Gab corresponding to a combination with the current frame tone value Gyb having a value larger than the current frame tone value Gyc among the tone values is acquired from the SDRAM 160.

The writing gradation selection unit 21 acquires the current frame gradation values Gya and Gyb corresponding to them from the SDRAM 160 in addition to the writing gradation values Gaa and Gab acquired as described above. Then, the writing gradation selection unit 21 writes the writing gradation values Gaa and Gab and the current frame gradation values Gya and Gyb acquired from the SDRAM 160 and the current frame gradation value Gyc that does not exist in the OS table LUT1. This is given to the gradation value-voltage conversion unit 23 in the gradation interpolation processing unit 22.

The gradation value-voltage conversion unit 23 converts the writing gradation values Gaa, Gab and the current frame gradation values Gya, Gyb, Gyc received from the writing gradation selection unit 21 into voltage values and outputs them. . In FIG. 7, the gradation voltages obtained by converting the writing gradation values Gaa, Gab and the current frame gradation values Gya, Gyb, Gyc received from the writing gradation selection unit 21 into voltage values are Vaa. , Vab, Vya, Vyb, and Vyc. Hereinafter, a gradation voltage obtained by converting a current frame gradation value into a voltage value is referred to as a “current frame gradation voltage”.

The interpolation calculation unit 24 receives the write gradation voltages Vaa and Vab and the current frame gradation voltages Vya, Vyb, and Vyc from the gradation value-voltage conversion unit 23, and performs a write step by linear interpolation processing using them. A regulated voltage Vvac is generated and output. Here, the linear interpolation processing in the first case is performed based on the following equation (2).
Vvac = Vaa + (Vab−Vaa) × (Vyc−Vya) / (Vyb−Vya)
... (2)

The voltage-gradation value conversion unit 25 receives the writing gradation voltage Vvac from the interpolation calculation unit 24, converts it into a gradation value (second writing gradation value), and outputs the second writing step. Second write gradation data WDb indicating a tone value is applied to the line buffer 130. As described above, the operation of the second case in the overdrive drive unit 122 is performed.

FIG. 8 is a diagram schematically showing the gradation value-gradation voltage characteristics for explaining the operation of the second case in the present embodiment. As shown in FIG. 8, in the second case, the conventional liquid crystal display device performs linear interpolation processing using the write tone values Gaa, Gab and the current frame tone values Gya, Gyb, Gyc, The writing gradation value Gac obtained by the interpolation processing is converted into the writing gradation voltage Vgac by the source driver 300 and applied to the liquid crystal. Since the response speed of the liquid crystal depends on the gradation voltage, the writing gradation voltage Vgac obtained by the linear interpolation processing based on the gradation value in the conventional liquid crystal display device does not become the above-described ideal writing voltage Vid. For this reason, in the conventional liquid crystal display device, an error voltage is generated in the first case. On the other hand, in the first case, the liquid crystal display device according to the present embodiment has a writing scale obtained by converting the writing gradation values Gaa, Gab and the current frame gradation values Gya, Gyb, Gyc into voltage values. The linear interpolation processing based on the above equation (2) is performed using the adjustment voltages Vaa, Vab and the current frame gradation voltages Vya, Vyb, Vyc, and the writing gradation voltage Vvac obtained by the linear interpolation processing is converted into gradation. The tone value is converted again into the writing tone voltage Vvac in the source driver 300 and applied to the liquid crystal. In this way, since the linear interpolation process in the present embodiment is performed based on the voltage value, the write gradation voltage Vvac obtained by the linear interpolation process becomes a value corresponding to the ideal write voltage Vid described above.

<1.3.2.3 Operation in the third case>
FIG. 9 is a diagram schematically showing a part of the OS table LUT1 in order to explain the operation of the third case in the present embodiment. As shown in FIG. 9, the OS table LUT1 corresponds to combinations of previous frame gradation values Gxa and Gxb, current frame gradation values Gya and Gyb, previous frame gradation values Gxa, and current frame gradation values Gya. Corresponding to the combination of the writing gradation value Gaa to be performed, the gradation value Gab corresponding to the combination of the previous frame gradation value Gxa and the current frame gradation value Gyb, and the previous frame gradation value Gxb and the current frame gradation value Gya There exists a writing gradation value Gba to be performed and a writing gradation value Gbb corresponding to a combination of the previous frame gradation value Gxb and the current frame gradation value Gyb. The previous frame gradation value Gxa is smaller than Gxb, the current frame gradation value Gya is smaller than Gyb, the writing gradation value Gaa is smaller than Gab and Gba, and the writing gradation value Gbb is smaller than Gab and Gba. Let it be big. Under such a premise, in the third case, the previous frame gradation value used for referring to the OS table LUT1 is Gxc that does not exist in the OS table LUT1, and the current frame gradation value is Gyc that does not exist in the OS table LUT1. The operation will be described. The previous frame gradation value Gxc is larger than the previous frame gradation value Gxa and smaller than Gxb. The current frame gradation value Gyc is larger than the current frame gradation value Gya and smaller than Gyb.

Since the writing gradation value corresponding to the combination of the previous frame gradation value Gxc and the current frame gradation value Gyc does not exist in the OS table LUT1, the writing gradation selection unit 21 exists in the OS table LUT1, and The previous frame gradation value Gxa, which is smaller than the previous frame gradation value Gxc, of the two previous frame gradation values closest to the previous frame gradation value Gxc, and exists in the OS table LUT1, and The writing gradation corresponding to the combination with the current frame gradation value Gya that is smaller than the current frame gradation value Gyc, out of the two current frame gradation values closest to the current frame gradation value Gyc The value Gaa is obtained from the SDRAM 160. Similarly, the write tone selection unit 21 is present in the OS table LUT1 and is more than the previous frame tone value Gxc of the two previous frame tone values closest to the previous frame tone value Gxc. The previous frame tone value Gxa having a smaller value and the current frame tone value Gyc of the two current frame tone values closest to the current frame tone value Gyc that are present in the OS table LUT1 The write gradation value Gab corresponding to the combination with the current frame gradation value Gyb having a large value is acquired from the SDRAM 160. Similarly, the write tone selection unit 21 is present in the OS table LUT1 and is more than the previous frame tone value Gxc of the two previous frame tone values closest to the previous frame tone value Gxc. The previous frame tone value Gxb having a large value and the current frame tone value Gyc of the two current frame tone values closest to the current frame tone value Gyc that are present in the OS table LUT1 The write gradation value Gba corresponding to the combination with the current frame gradation value Gya having a small value is acquired from the SDRAM 160. Similarly, the write tone selection unit 21 is present in the OS table LUT1 and is more than the previous frame tone value Gxc of the two previous frame tone values closest to the previous frame tone value Gxc. The previous frame tone value Gxb having a large value and the current frame tone value Gyc of the two current frame tone values closest to the current frame tone value Gyc that are present in the OS table LUT1 The write gradation value Gbb corresponding to the combination with the current frame gradation value Gyb having a large value is acquired from the SDRAM 160.

In addition to the writing tone values Gaa, Gab, Gba, and Gbb acquired as described above, the writing tone selection unit 21 adds the previous frame tone values Gxa, Gxb, and the current frame tone values corresponding thereto. Gya and Gyb are acquired from the SDRAM 160. Then, the writing gradation selection unit 21 writes the writing gradation values Gaa, Gab, Gba, Gbb, the previous frame gradation values Gxa, Gxb, the current frame gradation values Gya, Gyb acquired from the SDRAM 160, and the OS table. The previous frame gradation value Gxc and the current frame gradation value Gyc that do not exist in the LUT 1 are supplied to the gradation value-voltage conversion unit 23 in the writing gradation interpolation processing unit 22.

The gradation value-voltage conversion unit 23 receives the writing gradation values Gaa, Gab, Gba, Gbb, the previous frame gradation values Gxa, Gxb, Gxc, and the current frame gradation value received from the writing gradation selection unit 21. Each of Gya, Gyb, and Gyc is converted into a voltage value and output. In FIG. 9, the write tone values Gaa, Gab, Gba, Gbb, the previous frame tone values Gxa, Gxb, Gxc, and the current frame tone values Gya, Gyb, Gyc received from the write tone selecting unit 21 are obtained. The gradation voltages obtained by converting into voltage values are indicated by Vaa, Vab, Vba, Vbb, Vxa, Vxb, Vxc, Vya, Vyb, and Vyc, respectively.

The interpolation calculation unit 24 receives the write gradation voltages Vaa, Vab, Vba, Vbb, the previous frame gradation voltages Vxa, Vxb, Vxc, and the current frame gradation voltages Vya, Vyb, Vyc from the gradation value-voltage conversion unit 23. , And generates and outputs a write gradation voltage Vvc by linear interpolation processing using them. Here, in the linear interpolation process in the operation of the third case, a pattern for generating a write gradation voltage Vvc using a write gradation voltage Vvca and a write gradation voltage Vvcb described later, and a write gradation There are two patterns: a pattern for generating a write gradation voltage Vvc using a voltage Vvac and a write gradation voltage Vvbc described later.

First, in the pattern in which the write gradation voltage Vvc is generated using the write gradation voltages Vvca and Vvcb, the interpolation calculation unit 24 generates the write gradation voltage Vvca based on the above equation (1), and The write gradation voltage Vvcb is generated based on the following equation (3).
Vvcb = Vab + (Vbb−Vab) × (Vxc−Vxa) / (Vxb−Vxa)
... (3)

Then, the interpolation calculation unit 24 uses the writing gradation voltages Vvca and Vvcb generated based on the expressions (1) and (3), respectively, to write the writing gradation based on the following expression (4). Generate and output voltage Vvc.
Vvc = Vvca + (Vvcb−Vvca)
× (Vyc−Vya) / (Vyb−Vya) (4)

On the other hand, in the pattern in which the write gradation voltage Vvc is generated using the write gradation voltages Vvac and Vvbc, the interpolation calculation unit 24 generates the write gradation voltage Vvac based on the above equation (2). The write gradation voltage Vvbc is generated based on the following equation (5).
Vvbc = Vba + (Vbb−Vba) × (Vyc−Vya) / (Vyb−Vya)
... (5)

Then, the interpolation calculation unit 24 uses the writing gradation voltages Vvac and Vvbc generated based on the expressions (2) and (5), respectively, to write the writing gradation based on the following expression (6). Generate and output voltage Vvc.
Vvc = Vvac + (Vvbc−Vvac)
× (Vxc−Vxa) / (Vxb−Vxa) (6)

It should be noted that the above-described equations (1) are respectively used for a pattern for generating the write gradation voltage Vvc using the write gradation voltages Vvca and Vvcb and a pattern for generating the write gradation voltage Vvc using the write gradation voltages Vvac and Vvbc. The writing gradation voltage Vvc obtained based on 4) and Equation (6) has the same value.

The voltage-gradation value conversion unit 25 receives the writing gradation voltage writing gradation voltage Vvc from the interpolation operation unit 24, converts it into a gradation value (second writing gradation value), Second write gradation data WDb indicating a write gradation value of 2 is applied to the line buffer 130. As described above, the operation of the third case in the overdrive drive unit 122 is performed.

FIG. 10 is a diagram schematically showing the gradation value-gradation voltage characteristics in order to explain the operation of the third case in the present embodiment. Here, description will be made assuming that the write gradation voltage Vvc is obtained by a pattern for generating the write gradation voltage Vvc using the write gradation voltages Vvca and Vvcb. The same explanation holds true for a pattern in which the write gradation voltage Vvc is generated using Vvbc. As shown in FIG. 10, in the third case, the conventional liquid crystal display device has the write tone values Gaa, Gab, Gba, Gbb, the previous frame tone values Gxa, Gxb, Gxc, and the current frame tone value Gya. , Gyb, and Gyc are used to perform linear interpolation processing, and the writing gradation value Gc obtained by the linear interpolation processing is converted into writing gradation voltage Vgc by the source driver 300 and applied to the liquid crystal. Since the response speed of the liquid crystal depends on the gradation voltage, the writing gradation voltage Vgc obtained by the linear interpolation processing based on the gradation value in the conventional liquid crystal display device does not become the above-described ideal writing voltage Vid. For this reason, an error voltage is generated in the third case in the conventional liquid crystal display device. On the other hand, in the third case, the liquid crystal display device according to the present embodiment has the write tone values Gaa, Gab, Gba, Gbb, the previous frame tone values Gxa, Gxb, Gxc, and the current frame tone value. Write gradation voltages Vaa, Vab, Vba, Vbb, previous frame gradation voltages Vxa, Vxb, Vxc, which are obtained by converting gradation voltages obtained by converting Gya, Gyb, Gyc to voltage values, respectively, and Using the current frame gradation voltages Vya, Vyb, and Vyc, the linear interpolation processing based on the above equations (1), (3), and (4) is performed, and the writing gradation voltages obtained by the linear interpolation processing Vvc is converted into a gradation value, and the gradation value is converted again into the writing gradation voltage Vvc in the source driver 300 and applied to the liquid crystal. In this way, since the linear interpolation process in the present embodiment is performed based on the voltage value, the writing gradation voltage Vvc obtained by the linear interpolation process becomes a value corresponding to the above-described ideal writing voltage Vid.

<1.4 Effect>
According to the present embodiment, when there is no combination in the OS table LUT1, the overdrive driving unit 122 sets the first write gradation value, the previous frame gradation value, and the current frame gradation value to voltage values. Linear interpolation processing is performed using the converted gradation voltage, previous frame gradation voltage, and current frame gradation voltage. Then, the overdrive driving unit 122 converts the writing gradation voltage obtained by the linear interpolation processing into the second writing gradation value, and performs the second writing indicating the second writing gradation value. The gradation data WDb is output. Since the response speed of the liquid crystal depends on the gradation voltage, an ideal writing gradation voltage corresponding to the VT characteristic of the liquid crystal is obtained by performing linear interpolation processing using the gradation voltage as in this embodiment. be able to. Therefore, a more appropriate liquid crystal response speed can be obtained as compared with a conventional liquid crystal display device that performs overdrive driving using an OS table that requires a relatively small memory capacity. Thereby, high-quality moving image display can be performed at low cost.

Further, according to the present embodiment, since the linear interpolation process is used as the interpolation process, the above-described effects can be achieved with a simple process.

In the first to third cases in the present embodiment, the gradation value closest to the previous frame gradation value and / or the current frame gradation value and the first writing gradation corresponding to them. Although the value is used for the interpolation process, the gradation value other than the closest gradation value and the first written gradation value corresponding thereto may also be used for the interpolation process.

<2. Second Embodiment>
The second embodiment of the present invention predicts the arrival gradation of the previous frame gradation value in the first embodiment. Since the present embodiment has the same configuration and the like as those of the first embodiment except for the configuration and operation of the overdrive drive unit, the description of the common part is omitted. In addition, among the constituent elements of the present embodiment, the same elements as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

<2.1 Configuration of Overdrive Drive Unit>
FIG. 11 is a block diagram for explaining a detailed configuration of the overdrive driving unit 122 in the present embodiment. As shown in FIG. 11, the overdrive drive unit 122 in the present embodiment is the same as the configuration in the first embodiment described above, as the reached gradation selection unit 31 as the second gradation selection unit and the second interpolation unit. The arrival gradation interpolation processing unit 32 is added. The reached gradation interpolation processing unit 32 includes an interpolation calculation unit 24. The interpolation calculation unit 24 in the reached gradation interpolation processing unit 32 and the interpolation calculation unit 24 in the writing gradation interpolation processing unit 22 have the same functions. However, hereinafter, the interpolation calculation unit 24 in the reached gradation interpolation processing unit 32 is referred to as a “prediction interpolation calculation unit” for convenience.

By the way, in order to determine the reached gradation value that is predicted to reach the SDRAM 160 in the display on the liquid crystal display panel 5 based on the combination of the previous frame gradation value and the current frame gradation value. LUT2 of a lookup table (hereinafter referred to as “prediction table”) is stored. The prediction table LUT2 corresponds to a second lookup table. FIG. 12 is a diagram schematically illustrating an example of the prediction table LUT2 in the present embodiment. Here, in order to reduce the memory capacity, data for 16 gradations × 16 gradations are prepared in the prediction table LUT2. In FIG. 12, the numerical value indicated in the leftmost column indicates the previous frame gradation value, and the numerical value indicated in the uppermost line indicates the current frame gradation value. The numerical value written at the position where each row and each column intersect indicates the reached gradation value determined based on the combination of each previous frame gradation value and each current frame gradation value. For example, when the previous frame gradation value is “64” and the current frame gradation value is “128”, the reached gradation value is “128”. For example, when the previous frame gradation value is “128” and the current frame gradation value is “8”, the reached gradation value is “17”. Thus, the reached gradation value stored in the prediction table is the same as or larger than the current frame gradation value. Note that the prediction table LUT2 is stored in, for example, the flash memory 200, and the timing controller IC 100 reads the prediction table LUT2 from the flash memory 200 immediately after the apparatus is turned on, and writes it into the internal SDRAM 160.

The arrival gradation selection unit 31 refers to the prediction table LUT2 shown in FIG. 12 on the basis of the previous frame gradation value indicated by the previous frame data PD and the current frame gradation value indicated by the current frame data CD. The gradation value is determined, and the reached gradation data RD indicating the gradation value is written in the SDRAM 160 as the previous frame data PD in the next frame. However, when the combination of the previous frame gradation value and the current frame gradation value does not exist in the prediction table LUT2, the reached gradation selection unit 31 closes the previous frame gradation value and / or the current frame gradation value closest to the combination. The frame gradation value and the reached gradation value are given to the prediction interpolation calculation unit 24 in the reached gradation interpolation processing unit 32. The prediction interpolation calculation unit 24 uses the previous frame gradation value and / or the current frame gradation value and the arrival gradation value received from the arrival gradation selection unit 31 to correspond to combinations that do not exist in the prediction table LUT2. A linear interpolation process for obtaining the reached gradation value is performed, and the reached gradation data RD indicating the reached gradation value obtained by the interpolation process is written in the SDRAM 160 as the previous frame data PD in the next frame. Hereinafter, the reaching gradation data RD written from the reaching gradation selecting unit 31 to the SDRAM 160 is referred to as “first reaching gradation data”, and is represented by a symbol RDa. Further, the reached gradation data RD written to the SDRAM 160 from the reached gradation interpolation processing unit 32 (prediction interpolation calculation unit 24) is referred to as “second reached gradation data”, and is represented by the symbol RDb. Furthermore, the arrival gradation value indicated by the first arrival gradation data RDa is referred to as “first arrival gradation value”, and the arrival gradation value indicated by the second arrival gradation data RDb is referred to as “first arrival gradation value”. This is referred to as “2 reached gradation value”.

In the present embodiment, by using the prediction table LUT2, the previous frame gradation value indicated by the previous frame data PD received by the writing gradation selection unit 21 is the reached gradation value obtained in the previous frame. That is, the previous frame gradation value used when the writing gradation selection unit 21 refers to the OS table LUT1 is the current frame gradation value in the previous frame in the first embodiment, but in the present embodiment, The obtained gradation value is obtained. In accordance with this, the contents shown in FIG. 13 are used as the OS table LUT1 in the present embodiment, for example. This content is different from the OS table LUT1 shown in FIG. 4 in the first embodiment. Also in this embodiment, data for 16 gradations × 16 gradations are prepared in the OS table LUT1.

<2.2 Operation>
Next, the operation of the overdrive drive unit 122 in this embodiment will be described. However, since the operations of the writing gradation selection unit 21 and the writing gradation interpolation processing unit 22 are the same as those in the first embodiment, description thereof will be omitted. The reached gradation selection unit 31 receives the current frame data CD, and further reads the previous frame data PD stored in the SDRAM 160. Then, the reached gradation selection unit 31 refers to the prediction table LUT2 stored in the SDRAM 160 based on the previous frame gradation value indicated by the previous frame data PD and the current frame gradation value indicated by the current frame data CD. Thereafter, in the present embodiment, the combination of the previous frame gradation value and the current frame gradation value exists in the prediction table LUT2 (hereinafter, sometimes simply referred to as “there is a combination”) and does not exist (hereinafter referred to as “there is a combination”). The operations are different from each other simply by “when there is no combination”.

<2.2.1 Operation when a combination exists>
The operation when a combination exists is performed as follows. The reached tone selection unit 31 acquires from the SDRAM 160 first reached tone data RDa indicating the first reached tone value corresponding to the combination of the previous frame tone value and the current frame tone value. Then, the reached gradation selection unit 31 writes the first reached gradation data RDa in the SDRAM 160 as the previous frame data PD in the next frame.

<2.2.2 Operation when no combination exists>
The operation when there is no combination in the present embodiment is divided into the operation of the first case, the operation of the second case, and the operation of the third case, as in the first embodiment. In the operation of the first case, the operation of the second case, and the operation of the third case in the present embodiment, it is assumed that the OS table LUT1 shown in FIGS. 5, 7, and 9 is the prediction table LUT2. These FIGS. 5, 7, and 9 will be referred to as appropriate. Note that the same reference numerals as those in the first embodiment are used for the gradation values and gradation voltages.

<2.2.2.1 Operation in First Case>
In the operation of the first case, as shown in FIG. 5, since the arrival gradation value corresponding to the combination of the previous frame gradation value Gxc and the current frame gradation value Gya does not exist in the prediction table LUT2, the arrival gradation The selection unit 31 includes a previous frame level that is present in the prediction table LUT2 and has a value smaller than the previous frame gradation value Gxc among the two previous frame gradation values closest to the previous frame gradation value Gxc. A predicted gradation value Gaa corresponding to a combination of the key value Gxa and the current frame gradation value Gya existing in the prediction table LUT2 is acquired from the SDRAM 160. Similarly, the reached gradation selection unit 31 is present in the prediction table LUT2 and has a value greater than the previous frame gradation value Gxc of the two previous frame gradation values closest to the previous frame gradation value Gxc. The reached gradation value Gba corresponding to the combination of the previous frame gradation value Gxb having a large value and the current frame gradation value Gya existing in the prediction table LUT2 is acquired from the SDRAM 160.

The reached gradation selection unit 31 acquires the previous frame gradation values Gxa and Gxb from the SDRAM 160 in addition to the reached gradation values Gaa and Gba acquired as described above. Then, the reached gradation selection unit 31 uses the prediction gradation values Gaa and Gba and the previous frame gradation values Gxa and Gxb acquired from the SDRAM 160, and the previous frame gradation value Gxc that does not exist in the prediction table LUT2, as a prediction interpolation calculation. Part 24 is given.

The prediction interpolation calculation unit 24 performs a known linear interpolation process on the reached gradation value using the reached gradation values Gaa and Gba and the previous frame gradation values Gxa, Gxb, and Gxc, thereby performing the second arrival. Generate tone values. Thereafter, the prediction interpolation calculation unit 24 writes the second arrival gradation data RD indicating the second arrival gradation value into the SDRAM 160 as the previous frame data PD in the next frame.

<2.2.2.2 Second Case Operation>
In the operation of the second case, as shown in FIG. 7, since the arrival gradation value corresponding to the combination of the previous frame gradation value Gxa and the current frame gradation value Gyc does not exist in the prediction table LUT2, the arrival gradation The selection unit 31 selects the previous frame gradation value Gxa that exists in the prediction table LUT2 and the current frame gradation value that is present in the prediction table LUT2 and has the closest value to the current frame gradation value Gyc. The reached gradation value Gaa corresponding to the combination with the current frame gradation value Gya that is smaller than the current frame gradation value Gyc is acquired from the SDRAM 160. Similarly, the reached gradation selection unit 31 also includes two previous frame gradation values Gxa existing in the prediction table LUT2 and two current frame gradations present in the prediction table LUT2 and closest to the current frame gradation value Gyc. The reached gradation value Gab corresponding to the combination with the current frame gradation value Gyb having a value larger than the current frame gradation value Gyc is acquired from the SDRAM 160.

The reached gradation selection unit 31 acquires the current frame gradation values Gya and Gyb from the SDRAM 160 in addition to the reached gradation values Gaa and Gab acquired as described above. Then, the reached gradation selection unit 31 uses the write gradation values Gaa and Gab and the current frame gradation values Gya and Gyb acquired from the SDRAM 160 and the current frame gradation value Gyc that does not exist in the prediction table LUT2 for prediction interpolation. It gives to the calculating part 24.

The prediction interpolation calculation unit 24 performs a known linear interpolation process on the reached gradation value using the reached gradation values Gaa, Gab and the current frame gradation values Gya, Gyb, Gyc, thereby obtaining the second arrival value. Generate tone values. The subsequent operation is the same as in the first case.

<2.2.2.3 Operation in the third case>
In the operation of the third case, as shown in FIG. 9, since the arrival gradation value corresponding to the combination of the previous frame gradation value Gxc and the current frame gradation value Gyc does not exist in the prediction table LUT2, the arrival gradation The selection unit 31 includes a previous frame level that is present in the prediction table LUT2 and has a value smaller than the previous frame gradation value Gxc among the two previous frame gradation values closest to the previous frame gradation value Gxc. The current frame level having a value smaller than the current frame tone value Gyc, out of the two current frame tone values present in the prediction table LUT2 and closest to the current frame tone value Gyc. The reached gradation value Gaa corresponding to the combination with the tone value Gya is acquired from the SDRAM 160. Similarly, the reached gradation selection unit 31 is present in the prediction table LUT2 and has a value greater than the previous frame gradation value Gxc of the two previous frame gradation values closest to the previous frame gradation value Gxc. Is smaller than the current frame tone value Gyc of two current frame tone values that are present in the prediction table LUT2 and are closest to the current frame tone value Gyc. The reached gradation value Gab corresponding to the combination with the current frame gradation value Gyb having a large value is acquired from the SDRAM 160. Similarly, the reached gradation selection unit 31 is present in the prediction table LUT2 and has a value greater than the previous frame gradation value Gxc of the two previous frame gradation values closest to the previous frame gradation value Gxc. Is greater than the current frame tone value Gyc of the two current frame tone values that are present in the prediction table LUT2 and are closest to the current frame tone value Gyc. The reached gradation value Gba corresponding to the combination with the current frame gradation value Gya having a small value is acquired from the SDRAM 160. Similarly, the reached gradation selection unit 31 is present in the prediction table LUT2 and has a value greater than the previous frame gradation value Gxc of the two previous frame gradation values closest to the previous frame gradation value Gxc. Is greater than the current frame tone value Gyc of the two current frame tone values that are present in the prediction table LUT2 and are closest to the current frame tone value Gyc. The reached gradation value Gbb corresponding to the combination with the current frame gradation value Gyb having a large value is acquired from the SDRAM 160.

In addition to the reached gradation values Gaa, Gab, Gba, and Gbb acquired as described above, the reached gradation selection unit 31 includes the previous frame gradation values Gxa, Gxb and the current frame gradation values Gya, Gyb is acquired from the SDRAM 160. Then, the reached gradation selection unit 31 stores the reached gradation values Gaa, Gab, Gba, Gbb, the previous frame gradation values Gxa, Gxb, the current frame gradation values Gya, Gyb acquired from the SDRAM 160, and the prediction table LUT2. The pre-existing previous frame gradation value Gxc and the current frame gradation value Gyc are supplied to the prediction interpolation calculation unit 24.

The prediction interpolation calculation unit 24 uses the reached gradation values Gaa, Gab, Gba, Gbb, the previous frame gradation values Gxa, Gxb, Gxc, and the current frame gradation values Gya, Gyb, Gyc to achieve the reached gradation values. The second reached gradation value is generated by performing a known linear interpolation process for the above. The subsequent operation is the same as in the first case.

As described above, the reached gradation data RD indicating the reached gradation value is written in the SDRAM 160 as the previous frame data PD in the next frame.

<2.3 Effects>
According to the present embodiment, the reached gradation value obtained by using the prediction table LUT2 in the previous frame is used for referring to the OS table LUT1 as the previous frame gradation value in the current frame. Therefore, overdrive driving can be performed using the previous frame gradation value with higher accuracy than in the first embodiment. As a result, the response speed of the liquid crystal is corrected more appropriately, so that the image quality of the moving image display can be further improved.

In the first to third cases in the present embodiment, the tone value closest to the previous frame tone value and / or the current frame tone value, and the first reached tone value corresponding to them. Are used for the interpolation process, but a gradation value other than the closest gradation value and the first reached gradation value corresponding to the gradation value may also be used for the interpolation process (a third value described later). The same applies to the embodiment).

<3. Third Embodiment>
The third embodiment of the present invention performs linear interpolation processing using voltage values when there is no combination in the prediction table LUT2 in the second embodiment. Since the present embodiment has the same configuration and the like as the second embodiment except for the configuration and operation of the reached gradation interpolation processing unit 32, the description of the common portion is omitted. In addition, among the components of the present embodiment, the same elements as those in the second embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

<3.1 Configuration of Reaching Tone Interpolation Processing Unit>
FIG. 14 is a block diagram for explaining a detailed configuration of the reached gradation interpolation processing unit 32 in the overdrive driving unit 122 in the present embodiment. As shown in FIG. 14, the reached gradation interpolation processing unit 32 in the overdrive drive unit 122 in this embodiment includes a gradation value-voltage conversion unit 23 and a voltage in the preceding stage and the subsequent stage of the prediction interpolation calculation unit 24, respectively. A tone value conversion unit 25 is added. The gradation value-voltage conversion unit 23 and the voltage-gradation value conversion unit 25 in the reached gradation interpolation processing unit 32 are respectively the gradation value-voltage conversion unit 23 and the voltage- in the writing gradation interpolation processing unit 22. It has the same function as the gradation value conversion unit 25. However, in the following, the gradation value-voltage conversion unit 23 and the voltage-gradation value conversion unit 25 in the reached gradation interpolation processing unit 32 will be referred to as “prediction gradation value-voltage conversion unit” and “prediction This is called a “voltage-gradation value converter”.

<3.2 Operation>
Next, the operation of the first case, the operation of the second case, among the operations of the overdrive driving unit 122 in the present embodiment, particularly the operations in the reached gradation interpolation processing unit 32 when there is no combination, The operation of the third case will be described. The operation when there is a combination is the same as that in the second embodiment, and a description thereof will be omitted. Also, with regard to the operation of the first case, the operation of the second case, and the operation of the third case, description of portions common to the second embodiment will be omitted as appropriate.

<3.2.1 Operation in the first case>
The prediction gradation value-voltage conversion unit 23 receives the arrival gradation values Gaa and Gba and the previous frame gradation values Gxa, Gxb, and Gxc from the arrival gradation selection unit 31, and supplies them to the first embodiment. Similarly to the gradation value-voltage conversion unit 23 in FIG. Thereby, the reached gradation voltages Vaa, Vba and the previous frame gradation voltages Vxa, Vxb, Vxc are obtained. Here, “reached gradation voltage” refers to a gradation voltage obtained by converting the reached gradation value into a voltage value.

Unlike the second embodiment, the prediction interpolation calculation unit 24 receives the reached gradation voltages Vaa and Vba and the previous frame gradation voltages Vxa, Vxb, and Vxc from the prediction gradation value-voltage conversion unit 23, and The reached gradation voltage Vvca is generated and output based on the above equation (1).

The prediction voltage-gradation value conversion unit 25 receives the reached gradation voltage Vvca from the prediction interpolation calculation unit 24, and converts it to the gradation in the same manner as the voltage-gradation value conversion unit 25 in the first embodiment. Value (second reached gradation value). Then, the prediction voltage-gradation value conversion unit 25 writes the second arrival gradation data RD indicating the second arrival gradation value into the SDRAM 160 as the previous frame data PD in the next frame.

<3.2.2 Operation in the second case>
The prediction gradation value-voltage conversion unit 23 receives the arrival gradation values Gaa and Gab and the current frame gradation values Gya, Gyb, and Gyc from the arrival gradation selection unit 31, and supplies them to the first embodiment. Similarly to the gradation value-voltage conversion unit 23 in FIG. Thereby, the reached gradation voltages Vaa, Vab and the current frame gradation voltages Vya, Vyb, Vyc are obtained.

Unlike the second embodiment, the prediction interpolation calculation unit 24 receives the reached gradation voltages Vaa and Vab and the current frame gradation voltages Vya, Vyb, and Vyc from the prediction gradation value-voltage conversion unit 23, and Based on the above equation (2), the reached gradation voltage Vvac is generated and output.

The prediction voltage-gradation value conversion unit 25 receives the reached gradation voltage Vvac from the prediction interpolation calculation unit 24, and converts it to the gradation in the same manner as the voltage-gradation value conversion unit 25 in the first embodiment. Value (second reached gradation value). The subsequent operation is the same as in the first case.

<3.2.3 Operation in the third case>
The prediction gradation value-voltage conversion unit 23 receives the arrival gradation values Gaa, Gab, Gba, Gbb, the previous frame gradation values Gxa, Gxb, Gxc, and the current frame gradation value Gya, from the arrival gradation selection unit 31. Gyb and Gyc are received and converted into voltage values in the same manner as the gradation value-voltage conversion unit 23 in the first embodiment. Thus, the reached gradation voltages Vaa, Vab, Vba, Vbb, the previous frame gradation voltages Vxa, Vxb, Vxc, and the current frame gradation voltages Vya, Vyb, Vyc are obtained.

Unlike the second embodiment, the prediction interpolation calculation unit 24 receives the reached gradation voltages Vaa, Vab, Vba, Vbb and the previous frame gradation voltages Vxa, Vxb, Vxc from the prediction gradation value-voltage conversion unit 23. , And current frame gray scale voltages Vya, Vyb, Vyc. Then, the prediction interpolation calculation unit 24 generates the write gradation voltage Vvc based on the above (4) using the reached gradation voltages Vvca and Vvcb obtained based on the above (1) and the expression (3), respectively. Or, using the reached gradation voltages Vvac and Vvbc obtained respectively based on the above equations (2) and (5), the write gradation voltage Vvc is generated based on the above equation (6). Output.

The prediction voltage-gradation value conversion unit 25 receives the reached gradation voltage Vvc from the prediction interpolation calculation unit 24, and converts it to the gradation in the same manner as the voltage-gradation value conversion unit 25 in the first embodiment. Value (second reached gradation value). The subsequent operation is the same as in the first case.

In the operation of the first to third cases in the present embodiment, the above error voltage does not occur for the same reason as the operation of the first to third cases in the first embodiment. However, the details are omitted because the writing gradation value and the writing gradation voltage are respectively replaced with the reaching gradation value and the reaching gradation voltage in the description of the first embodiment.

<3.3 Effects>
According to the present embodiment, the linear interpolation process when the combination does not exist in the prediction table LUT2 is performed by using the gradation voltage. For this reason, since the linear interpolation process is performed in consideration of the VT characteristics of the liquid crystal, an accurate reached gradation value can be obtained as compared with the second embodiment. Since the reached gradation value obtained in this manner is used for overdrive driving as the previous frame gradation value, the response speed of the liquid crystal is corrected more appropriately than in the second embodiment. Thereby, the image quality of moving image display can be further improved.

<4. Other>
The contents of the lookup tables shown in FIGS. 4, 12, and 13 are merely examples, and the lookup tables used in the present invention are not limited to the contents. In the second and third embodiments, the writing gradation interpolation processing unit 22 and the reached gradation interpolation processing unit 24 are separate components, but may be realized as a single component. good. In each of the above embodiments, linear interpolation processing is used as interpolation processing, but other interpolation processing may be used. In addition, the above-described embodiments can be variously modified and implemented without departing from the spirit of the present invention.

As described above, according to the present invention, it is possible to provide a display control circuit that enables high-quality moving image display at low cost, a liquid crystal display device including the display control circuit, and a display control method.

The present invention can be applied to a display control circuit for performing overdrive driving that emphasizes a temporal change of a signal with respect to an image signal, a liquid crystal display device including the display control circuit, and a display control method.

5. Liquid crystal display panel 21. Writing gradation selection section (first gradation selection section)
22... Write gradation interpolation processing unit (first interpolation unit)
23 ... gradation value-voltage conversion unit 24 ... interpolation calculation unit 25 ... voltage-gradation value conversion unit 31 ... reached gradation selection unit (second gradation selection unit)
32 .. reached gradation interpolation processing unit (second interpolation unit)
100 ... Timing controller IC (display control circuit)
122: Overdrive drive unit 160: SDRAM (storage unit)
LUT1 ... OS table (first lookup table)
LUT2 ... Prediction table (second lookup table)
CD ... current frame data PD ... previous frame data WDa ... first writing gradation data WDb ... second writing gradation data RDa ... first reaching gradation data RDb ... second reaching gradation data Gxa, Gxb, Gxc: previous frame gradation values Gya, Gyb, Gyc: current frame gradation values Gaa, Gab, Gba, Gbb, Gca, Gac, Gcb, Gc: write gradation values, reached gradation values Vxa, Vxb, Vxc: previous frame gradation voltage Vya, Vyb, Vyc: current frame gradation voltage Vaa, Vab, Vba, Vbb, Vca, Vgca, Vgac, Vgc, Vvca, Vvac, Vvcb, Vvbc, Vvc, Vid ... writing gradation Voltage, ultimate gradation voltage

Claims

A display control circuit for controlling display on a liquid crystal display panel based on an image signal given from the outside,
A writing gradation value used for correction for emphasizing a temporal change of the signal with respect to the image signal is given in the previous frame gradation value which is a gradation value in a frame immediately before the current frame, and in the current frame. A storage unit storing a first look-up table for determination based on a combination of current frame gradation values which are gradation values of the image signal;
The first look-up table is referred to, and when the combination exists in the first look-up table, the writing gradation value determined based on the combination is output, and the combination is the first look-up table. If not present in one lookup table, the previous frame tone value and / or the current frame tone value corresponding to the combination closest to the combination and present in the first lookup table And a first gradation selection unit that outputs at least the write gradation value;
When the combination does not exist in the first lookup table, the previous frame gradation value and / or the current frame gradation value and the writing gradation value output from the first gradation selection unit Are converted into voltage values, and interpolation processing for obtaining the writing gradation values corresponding to the combinations not existing in the first look-up table is performed using the voltage values. A display control circuit comprising an interpolation unit.
The display control circuit according to claim 1, wherein the interpolation process performed by the first interpolation unit is a linear interpolation process.
The first gradation selection unit is closest to the previous frame gradation value when only the previous frame gradation value is not present in the first lookup table in the combination, and The previous frame gradation value existing in the first look-up table and the writing gradation value determined based on a combination of the previous frame gradation value and the current frame gradation value are output. The display control circuit according to claim 2, wherein:
When only the current frame gradation value does not exist in the first lookup table, the first gradation selection unit is closest to the current frame gradation value, and And outputting the current frame gradation value existing in the first look-up table and the writing gradation value determined based on a combination of the current frame gradation value and the previous frame gradation value. The display control circuit according to claim 2, wherein:
When the previous frame gradation value and the current frame gradation value constituting the combination do not exist in the first lookup table, the first gradation selection unit The previous frame tone value, the current frame tone value, the previous frame tone value, and the current frame that are closest to the current frame tone value and exist in the first lookup table. The display control circuit according to claim 2, wherein the writing gradation value determined based on a combination of gradation values is output.
The display control circuit according to claim 1, wherein the previous frame gradation value is the current frame gradation value in a frame immediately before the current frame.
The storage unit further includes a second lookup table for determining a reached gradation value, which is a gradation value predicted to be reached in the display on the liquid crystal display panel, based on the combination,
When the second lookup table is referred to and the combination exists in the second lookup table, the reached gradation value is set as the previous frame gradation value in the frame immediately after the current frame. , If the combination does not exist in the second lookup table, the previous frame tone value that is closest to the combination and that corresponds to the combination present in the second lookup table and / or A second gradation selection unit that outputs at least the current frame gradation value and the reached gradation value;
When the combination does not exist in the second look-up table, based on the previous frame gradation value and / or the current frame gradation value and the reached gradation value output from the second selection unit. Thus, the reached gradation value obtained by performing interpolation processing in a predetermined format for acquiring the reached gradation value corresponding to the combination that does not exist in the second lookup table is determined as the current frame. The display control circuit according to claim 1, further comprising: a second interpolation unit that sets the previous frame gradation value in the immediately following frame.
The second interpolation unit converts each of the previous frame tone value and / or the current frame tone value and the reached tone value output from the second selection unit into a voltage value, and 8. The display control according to claim 7, wherein the interpolation processing for acquiring the reached gradation value corresponding to the combination that does not exist in the second look-up table is performed using a voltage value. 9. circuit.
The display control circuit according to claim 8, wherein the interpolation processing performed by the second interpolation unit is linear interpolation processing.
When only the previous frame gradation value does not exist in the second lookup table in the combination, the second gradation selection unit is closest to the previous frame gradation value, and Outputting the previous frame gradation value existing in the second look-up table and the reached gradation value determined based on a combination of the previous frame gradation value and the current frame gradation value. The display control circuit according to claim 9, wherein:
When only the current frame tone value does not exist in the second look-up table in the combination, the second tone selecting unit is closest to the current frame tone value, and Outputting the current frame gradation value existing in the second look-up table and the reached gradation value determined based on a combination of the current frame gradation value and the previous frame gradation value. The display control circuit according to claim 9, wherein:
The second gradation selection unit, when the previous frame gradation value and the current frame gradation value constituting the combination do not exist in the second lookup table, The previous frame gradation value, the current frame gradation value, the previous frame gradation value, and the current frame that are closest to the current frame gradation value and exist in the second lookup table. The display control circuit according to claim 9, wherein the reached gradation value determined based on a combination of gradation values is output.
A display control circuit according to any one of claims 1 to 12,
A liquid crystal display device comprising: the liquid crystal display panel for performing display based on the writing gradation value obtained by the display control circuit.
A display control method for controlling display on a liquid crystal display panel based on an image signal given from outside,
A writing gradation value used for correction for emphasizing a temporal change of the signal with respect to the image signal is given in the previous frame gradation value which is a gradation value in a frame immediately before the current frame, and in the current frame. Referring to a first lookup table for determining based on a combination of current frame tone values that are tone values of the image signal;
Outputting the writing gradation value determined based on the first combination when the combination exists in the first lookup table;
If the combination does not exist in the first lookup table, the previous frame tone value and / or the current value that is closest to the combination and that corresponds to the combination that exists in the first lookup table. Outputting at least a frame gradation value and the writing gradation value;
Converting each of the previous frame gradation value and / or the current frame gradation value and the writing gradation value output when the combination does not exist in the first lookup table into a voltage value; And a step of performing an interpolation process for obtaining the writing gradation value corresponding to the combination that does not exist in the first look-up table using the voltage value. .