JP2021128289A - Liquid crystal display device - Google Patents

Abstract

To solve a problem that, when the write polarity to the data signal line changes, large ripple occurs in a potential of a common electrode or the like, and the display quality deteriorates.SOLUTION: A control part of a liquid crystal display device performs a step (S1) of converting the input gradation of the target line into the linear conversion gradation in which a gradation voltage characteristic becomes linear, and a second step (S2-S6) of, in comparison between the target line and the preceding line, correcting at least one of linear conversion gradations of the target line when the sum of the difference of the linear conversion gradation between two pixels adjacent to each other in the column direction exceeds a threshold value, and generating the output gradation of the target line based on the corrected result.SELECTED DRAWING: Figure 4

Description

The present invention relates to a liquid crystal display device.

Patent Document 1 discloses a liquid crystal display device in which a plurality of pixels are arranged in a matrix, in which the polarity of a voltage applied to the plurality of pixels is inverted for each of the plurality of pixel rows.

JP-A-2007-279765 (published on October 25, 2007)

In the configuration of Patent Document 1 (conventional configuration), the potentials of a plurality of data signal lines arranged over the entire display unit change from negative to positive or positive to negative at the same time, so that the potential (Vcom) of the common electrode and the auxiliary There is a problem that a large ripple occurs in the potential of the capacitive wiring and the display quality deteriorates.

The display device according to one aspect of the present invention is a liquid crystal display including a display unit including a plurality of data signal lines, a plurality of scanning signal lines, and a plurality of pixels, a drive unit for driving the display unit, and a control unit. In the device, the display unit includes a plurality of lines each consisting of a plurality of pixels, and the control unit sets the input gradation of the target line to a linear conversion gradation in which the gradation voltage characteristic is linear. In the first step of converting to The second step of correcting at least one of the conversion gradations and generating the output gradation of the target line based on the correction result is performed, and the drive unit performs the target line based on the output gradation of the target line. Supply voltage to multiple pixels of.

According to one aspect of the present invention, ripples generated in the potential of the common electrode and the like can be suppressed, and the display quality can be improved as compared with the conventional configuration.

It is a block diagram which shows the structure of the liquid crystal display device which concerns on this embodiment. FIG. 2A is a schematic diagram showing the configuration of the display unit, and FIG. 2B is a circuit diagram showing the configuration of pixels. It is a flowchart which shows the operation of a control part. It is a graph which shows the input gradation-voltage characteristic (curve) and the linear transformation gradation-voltage characteristic (straight line). It is a table which shows the correction method of the linear transformation gradation in Example 1. It is a schematic diagram which shows the effect of Example 1. FIG. It is a table which shows another correction method of the linear transformation gradation in Example 1. FIG. It is a table which shows still another correction method of the linear transformation gradation in Example 1. FIG. 9 (a) is a table showing a correction method of the linear conversion gradation in the second embodiment, and FIG. 9 (b) is a table showing another correction method of the linear conversion gradation in the second embodiment. (C) is a table showing still another correction method of the linear transformation gradation in the second embodiment.

FIG. 1 is a plan view showing a configuration of a liquid crystal display device according to the present embodiment. As shown in FIG. 1, the liquid crystal display device 3 according to the present embodiment includes a display unit 20 that includes a plurality of pixels and displays an image, a drive unit 30 that drives the display unit 20, a processor 42, and a memory 44. It includes a control unit 40 that receives video data and controls the drive unit 30.

FIG. 2A is a schematic diagram showing the configuration of the display unit, and FIG. 2B is a circuit diagram showing the configuration of pixels. The display unit 20 includes a plurality of data signal lines S0 to S10, a plurality of scanning signal lines G1 to G4, and a plurality of pixel PXs. Each of the pixel rows H1 to H3 is composed of a plurality of pixels PX arranged in the row direction.

For example, as shown in FIG. 2B, one pixel PX of the pixel row H1 includes the pixel electrode PE, and the pixel electrode PE is connected to the scanning signal line G1 and the data signal line S0 via the transistor Tr. , Auxiliary capacitance wiring CS1 and capacitance Ccs are formed, and common electrode COM and capacitance Clc are formed. A plurality of pixels in the same pixel line are connected to the same scanning signal line and are connected to different data signal lines.

FIG. 3 is a flowchart showing the operation of the control unit. FIG. 4 is a graph showing an input gradation-voltage characteristic (curve) and a linear conversion gradation-voltage characteristic (straight line). As shown in FIG. 3, the control unit 40 of FIG. 1 converts the input gradation of the target pixel row (hereinafter referred to as the target row) into a linear conversion gradation having a linear gradation voltage characteristic. In one step (step St1) and the comparison between the target row and its previous row, if the sum of the linear conversion gradation differences between two adjacent pixels in the column direction exceeds the threshold value, the linear conversion of the target row The second step (steps St2 to St6) of correcting at least one of the gradations and generating the output gradation of the target line based on the correction result is performed, and the output gradation is output to the drive unit 30 (step). St7).

In step St1, the linear conversion gradation (with positive or negative polarity) is calculated from the input gradation of the target line based on the video data input from the outside and the linear conversion gradation-voltage characteristic Yc in FIG. For example, a linear conversion gradation 0 is calculated for an input gradation 0, a linear conversion gradation +255 or -255 is calculated for an input gradation 255, and a linear conversion scale is calculated for an input gradation 200. Calculate key +128 or -128. In step St1, an input gradation that has undergone pretreatment such as overshoot may be used.

In step St2, the target row and the previous row are compared, and the total sum of the differences in the linear transformation gradations (differences in the linear transformation gradations between two adjacent pixels in the column direction) is calculated.

In step St3, it is determined whether or not the sum of the differences exceeds the threshold value. If NO in step St3, the process proceeds to step St4, and the linear conversion gradation of the target line is output by re-conversion using the input gradation / output gradation-voltage characteristic Ya in FIG. 4 without correction. Generate gradation.

If YES in step St3 (when the threshold is exceeded), the process proceeds to step St5, and at least one of the linear transformation gradations of the target row is corrected so that the sum of the differences is reduced. Here, only the polarity may be changed without changing the absolute gradation value (magnitude of gradation), only the absolute gradation value may be changed without changing the polarity, and the polarity and the absolute gradation value may be changed. May be changed (described later).

In step St6 following step St5, the output gradation is generated by reconverting the linear conversion gradation of the corrected target line using the input gradation / output gradation-voltage characteristic Ya of FIG.

In step St7, the output gradation generated in step St4 or step St6 is output to the drive unit 30 (source driver for driving the data signal line).

The drive unit 30 supplies a voltage to a plurality of pixels PX of the target row based on the output gradation of the target row. Specifically, an analog signal voltage is written to the pixel electrode PE of the pixel PX via the corresponding data signal line (S0 to S10) and the transistor Tr.

[Example 1]
FIG. 5 is a table showing a method for correcting linear transformation gradation in the first embodiment. In the first embodiment, the horizontal line inversion drive (drive that inverts the polarity for each line) is used as a base. Therefore, the linear transformation gradations of the target rows (H2 / H3) obtained in step St1 of FIG. 4 have the same polarity.
For the target line H2, the linear conversion gradation of the pixels connected to the data signal lines S0 to S3 and S10 is −128, and the linear conversion gradation of the pixels connected to the data signal lines S4 to S9 is -255. For the previous row H1 of the target row H2, the linear conversion gradation of the pixels connected to the data signal lines S0 to S10 is +128.

In this case, in the comparison between the target row H2 and the previous row H1, the total sum of the differences in the linear transformation gradations between the two pixels adjacent to each other in the column direction is -256 × 5-383 × 6 = −3578. It should be noted that a ripple having a magnitude corresponding to this sum is generated in the potential (Vcom) of the common electrode COM and the potential of the auxiliary capacitance wiring CS2.

Here, since the sum of the differences (-3578) exceeds the threshold value (-3000), one or more of the linear transformation gradations of the target row H2 are corrected. Here, the linear conversion gradations (6) of the pixels connected to the data signal lines S4 to S9 are corrected from -255 to +255 (that is, only the polarity is changed without changing the absolute gradation value). After the correction, for the target row H2 and the previous row H1, the total sum of the differences in the linear conversion gradations between the two adjacent pixels in the column direction is -518, which is within the threshold value (-3000). It is possible to effectively suppress the occurrence of ripples in the horizontal scanning period (writing period) corresponding to.

For the target line H3, the linear conversion gradation of the pixels connected to the data signal lines S0 to S3 and S10 is +128, and the linear conversion gradation of the pixels connected to the data signal lines S4 to S9 is +255. Regarding the previous line H2 (linear conversion gradation before correction) of the target line H3, the linear conversion gradation of the pixels connected to the data signal lines S0 to S3 and S10 is -128, and the data signal lines S4 to S9 are connected. The linear conversion gradation of the pixels to be processed is -255.

In this case, in the comparison between the target row H3 and the previous row H2, the total sum of the differences in the linear transformation gradations between the two pixels adjacent to each other in the column direction is +256 × 5 + 510 × 6 = + 4340. In this comparison, the linear conversion gradation before the correction of the previous line H2 is used in order to suppress the increase in memory and prevent the drive from being largely deviated from the base horizontal line inversion (polarity inversion for each line) drive. be. However, the present invention is not limited to this, and the corrected linear conversion gradation of the previous row H2 may be used in the comparison between the target row H3 and its preceding row H2.

Here, since the total difference (+4340) exceeds the threshold value (−3000 to +3000), one or more of the linear transformation gradations of the target row H3 are corrected. Here, the linear conversion gradations (6 pieces) of the pixels connected to the data signal lines S4 to S9 are corrected from +255 to -255 (that is, only the polarity is changed without changing the absolute gradation value). After the correction, for the target row H3 and the previous row H2, the total sum of the differences in the linear transformation gradations between the two adjacent pixels in the column direction is -1780, which is within the threshold value (-3000). It is possible to effectively suppress the occurrence of ripples in the horizontal scanning period (writing period) corresponding to.

FIG. 6 is a schematic view showing the effect of the first embodiment. Before the correction, the gray zones on both sides of the high-luminance region (for example, the white region) become dark as shown in FIG. 6A due to the large ripple generated in the potential Vcom of the common electrode. Later, by suppressing the ripple, the phenomenon that the gray zones on both sides of the high-luminance region become dark as shown in FIG. 6B is almost eliminated.

FIG. 7 is a table showing another correction method of the linear transformation gradation in the first embodiment. In FIG. 7, in the comparison between the target row H2 and the previous row H1, the total sum of the differences in the linear transformation gradations between the two pixels adjacent to each other in the column direction is -256 × 5-383 × 6 = −3578. .. Here, since the sum of the differences (-3578) exceeds the threshold value (-3000), one or more of the linear transformation gradations of the target row H2 are corrected. Specifically, the linear conversion gradation (6 pieces) of the pixels connected to the data signal lines S4 to S9 is corrected from -255 to -230 (that is, only the absolute gradation value is changed without changing the polarity). , The linear conversion gradation (five) of the pixels connected to the data signal lines S0 to S3 and S10 is corrected from -128 to -118 (that is, only the absolute gradation value is changed without changing the polarity).

After the correction, for the target row H2 and the previous row H1, the total sum of the differences in the linear transformation gradations between the two adjacent pixels in the column direction is -3378, which is smaller than that before the correction, and therefore corresponds to the target row H2. It is possible to suppress the occurrence of ripples during the horizontal scanning period (writing period).

Further, in the comparison between the target row H3 and the previous row H2, the total sum of the differences in the linear transformation gradations between the two pixels adjacent to each other in the column direction is +256 × 5 + 510 × 6 = + 4340. Here, since the total difference (+4340) exceeds the threshold value (−3000 to +3000), one or more of the linear transformation gradations of the target row H3 are corrected. Specifically, the linear conversion gradation (6 pieces) of the pixels connected to the data signal lines S4 to S9 is corrected from +255 to +230 (that is, only the absolute gradation value is changed without changing the polarity), and the data. The linear conversion gradation (five) of the pixels connected to the signal lines S0 to S3 and S10 is corrected from +128 to +118 (that is, only the absolute gradation value is changed without changing the polarity).

After the correction, the sum of the differences in the linear transformation gradations between the two adjacent pixels in the column direction is +3940 for the target row H3 and the previous row H2, which is smaller than that before the correction, and therefore corresponds to the target row H3. It is possible to suppress the occurrence of ripple during the horizontal scanning period (writing period).

FIG. 8 is a table showing still another correction method of the linear transformation gradation in the first embodiment. In FIG. 7, in the comparison between the target row H2 and the previous row H1, the total sum of the differences in the linear transformation gradations between the two pixels adjacent to each other in the column direction is -256 × 5-383 × 6 = −3578. .. Here, since the sum of the differences (-3578) exceeds the threshold value (-3000), one or more of the linear transformation gradations of the target row H2 are corrected. Specifically, the linear conversion gradation (6 pieces) of the pixels connected to the data signal lines S4 to S9 is corrected from -255 to +255 (that is, only the polarity is changed without changing the absolute gradation value). The linear conversion gradation (five) of the pixels connected to the data signal lines S0 to S3 and S10 is corrected from -128 to -118 (that is, only the absolute gradation value is changed without changing the polarity).

After the correction, for the target row H2 and the previous row H1, the total sum of the differences in the linear conversion gradations between the two adjacent pixels in the column direction is -468, which is within the threshold value. The occurrence of ripple during the scanning period (writing period) can be effectively suppressed.

Further, in the comparison between the target row H3 and the previous row H2, the total sum of the differences in the linear transformation gradations between the two pixels adjacent to each other in the column direction is +256 × 5 + 510 × 6 = + 4340. Here, since the total difference (+4340) exceeds the threshold value (−3000 to +3000), one or more of the linear transformation gradations of the target row H3 are corrected. Specifically, the linear conversion gradation (6 pieces) of the pixels connected to the data signal lines S4 to S9 is corrected from +255 to -246 (that is, the polarity and the absolute gradation value are changed), and the data signal line S0 The linear conversion gradations (5) of the pixels connected to ~ S3 and S10 are corrected from +128 to +138 (that is, only the absolute gradation value is changed without changing the polarity).

After the correction, for the target row H3 and the previous row H2, the total sum of the differences in the linear transformation gradations between the two adjacent pixels in the column direction is -1672, which is within the threshold value. The occurrence of ripple during the scanning period (writing period) can be effectively suppressed.

[Example 2]
FIG. 9A is a table showing a correction method of the linear conversion gradation in the second embodiment, and FIG. 9B is a table showing another correction method of the linear conversion gradation in the second embodiment. (C) is a table showing still another correction method of the linear transformation gradation in the second embodiment. In the second embodiment, the vertical line inversion drive (drive that inverts the polarity for each row) is used as a base. Therefore, the linear transformation gradation of the target row (H2) obtained in step St1 of FIG. 4 has two polarities.

For the target line H2, the linear conversion gradation of the pixels connected to the data signal lines S0, S2, S4, S6, S8, and S10 is -128, and the data signal lines S1, S3, S5, S7, and S9 are connected. The linear conversion gradation of the pixels is +255. For the previous line H1 of the target line H2, the linear conversion gradation of the pixels connected to the data signal lines S0, S2, S4, S6, S8, S10 is -128, and the data signal lines S1, S3, S5, S7, and so on. The linear conversion gradation of the pixels connected to S9 is +128.

In FIG. 9A, in the comparison between the target row H2 and the previous row H1, the total sum of the differences in the linear transformation gradations between the two pixels adjacent to each other in the column direction is 127 × 5 = + 635. Here, since the sum of the differences (+635) exceeds the threshold value (+500), one or more of the linear transformation gradations of the target row H2 are corrected. Specifically, the linear conversion gradation of the pixel connected to the data signal line S1 is corrected from +255 to -255 (that is, only the polarity is changed without changing the absolute gradation value).

After the correction, for the target row H2 and the previous row H1, the total sum of the differences in the linear transformation gradations between the two adjacent pixels in the column direction is +125, which is within the threshold value. The occurrence of ripples during the period can be effectively suppressed.

In FIG. 9B, in the comparison between the target row H2 and the previous row H1, the total sum of the differences in the linear transformation gradations between the two pixels adjacent to each other in the column direction is 127 × 5 = + 635. Here, since the sum of the differences (+635) exceeds the threshold value (+500), one or more of the linear transformation gradations of the target row H2 are corrected. Specifically, the linear conversion gradation of the pixels connected to the data signal lines S1, S3, S5, S7, and S9 is corrected from +255 to +230 (that is, only the absolute gradation value is changed without changing the polarity). ..

After the correction, for the target row H2 and the previous row H1, the total sum of the differences in the linear transformation gradations between the two adjacent pixels in the column direction is +510, which is smaller than that before the correction, and therefore corresponds to the target row H2. The occurrence of ripple during the horizontal scanning period can be suppressed.

In FIG. 9C, in the comparison between the target row H2 and the previous row H1, the total sum of the differences in the linear transformation gradations between the two pixels adjacent to each other in the column direction is 127 × 5 = + 635. Here, since the sum of the differences (+635) exceeds the threshold value (+500), one or more of the linear transformation gradations of the target row H2 are corrected. Specifically, the linear conversion gradation of the pixel connected to the data signal line S1 is corrected from +255 to -255 (that is, only the polarity is changed without changing the absolute gradation value), and the data signal lines S3 and S5. -Correct the linear conversion gradation of the pixels connected to S7 and S9 from +255 to +240 (that is, change only the absolute gradation value without changing the polarity).

After the correction, for the target row H2 and the previous row H1, the total sum of the differences in the linear transformation gradations between the two adjacent pixels in the column direction is +65, which is within the threshold value. The occurrence of ripples during the period can be effectively suppressed.

Each of the above embodiments is for purposes of illustration and description, not for limitation. Based on these examples and explanations, it will be apparent to those skilled in the art that many variants are possible. A television receiver including the liquid crystal display device 3 is also included in the present embodiment.

〔summary〕
[Aspect 1]
A liquid crystal display device including a display unit including a plurality of data signal lines, a plurality of scanning signal lines, and a plurality of pixels, a drive unit for driving the display unit, and a control unit.
The display unit includes a plurality of lines, each of which is composed of a plurality of pixels.
The control unit is adjacent to each other in the column direction in the first step of converting the input gradation of the target row into a linear conversion gradation in which the gradation voltage characteristic is linear, and in the comparison between the target row and the previous row. When the sum of the differences between the linear transformation gradations between the two pixels exceeds the threshold value, at least one of the linear transformation gradations of the target row is corrected, and the output gradation of the target row is generated based on the correction result. Perform the second step and
The drive unit is a liquid crystal display device that supplies a voltage to a plurality of pixels of the target line based on the output gradation of the target line.

[Aspect 2]
The liquid crystal display device according to, for example, the first aspect, wherein the linear transformation gradation of the target line obtained in the first step has a positive or negative polarity.

[Aspect 3]
The liquid crystal display device according to, for example, Aspect 1 or 2, wherein the sum of the differences in the linear conversion gradations of the target line does not exceed the threshold value after the correction of the linear conversion gradations of the target line.

[Aspect 4]
Multiple pixels in the target line are connected to the same scanning signal line,
The liquid crystal display device according to any one of aspects 1 to 3, for example, wherein a plurality of pixels of the target line are connected to different data signal lines.

[Aspect 5]
The liquid crystal display device according to, for example, the second aspect, wherein the control unit changes at least one polarity of the linear conversion gradation of the target line in the second step, but does not change the absolute value of the gradation.

[Aspect 6]
The liquid crystal display device according to, for example, the second aspect, wherein the control unit changes at least one gradation absolute value of the linear transformation gradation of the target line in the second step, but does not change its polarity.

[Aspect 7]
The liquid crystal display device according to, for example, the second aspect, wherein the control unit changes at least one polarity and an absolute gradation value of the linear transformation gradation of the target line in the second step.

[Aspect 8]
The liquid crystal display device according to, for example, the second aspect, wherein the linear transformation gradation of the target line obtained in the first step has the same polarity.

[Aspect 9]
The liquid crystal display device according to, for example, any one of aspects 1 to 7, wherein the display unit includes a common electrode common to the plurality of rows.

[Aspect 10]
The liquid crystal display device according to, for example, any one of aspects 1 to 7, wherein the display unit includes auxiliary capacitance wiring common to the plurality of rows.

3 Liquid crystal display 20 Display unit 30 Drive unit 40 Control unit G1 to G4 Scanning signal line CS1 to CS4 Auxiliary capacitance wiring S0 to S10 Data signal line H2 / H3 Target line

Claims (10)

A liquid crystal display device including a display unit including a plurality of data signal lines, a plurality of scanning signal lines, and a plurality of pixels, a drive unit for driving the display unit, and a control unit.
The display unit includes a plurality of lines, each of which is composed of a plurality of pixels.
The control unit is adjacent to each other in the column direction in the first step of converting the input gradation of the target row into a linear conversion gradation in which the gradation voltage characteristic is linear, and in the comparison between the target row and the previous row. When the sum of the differences between the linear transformation gradations between the two pixels exceeds the threshold value, at least one of the linear transformation gradations of the target row is corrected, and the output gradation of the target row is generated based on the correction result. Perform the second step and
The drive unit is a liquid crystal display device that supplies a voltage to a plurality of pixels of the target line based on the output gradation of the target line. The liquid crystal display device according to claim 1, wherein the linear transformation gradation of the target line obtained in the first step has positive or negative polarity. The liquid crystal display device according to claim 1 or 2, wherein the sum of the differences in the linear conversion gradations of the target line does not exceed the threshold value after the correction of the linear conversion gradations of the target line. Multiple pixels in the target line are connected to the same scanning signal line,
The liquid crystal display device according to any one of claims 1 to 3, wherein a plurality of pixels of the target line are connected to different data signal lines. The liquid crystal display device according to claim 2, wherein the control unit changes at least one polarity of the linear conversion gradation of the target line in the second step, but does not change the absolute value of the gradation. The liquid crystal display device according to claim 2, wherein the control unit changes at least one gradation absolute value of the linear conversion gradation of the target line in the second step, but does not change the polarity. The liquid crystal display device according to claim 2, wherein the control unit changes at least one polarity and an absolute gradation value of the linear conversion gradation of the target line in the second step. The liquid crystal display device according to claim 2, wherein the linear conversion gradation of the target line obtained in the first step has the same polarity. The liquid crystal display device according to any one of claims 1 to 7, wherein the display unit includes a common electrode common to the plurality of rows. The liquid crystal display device according to any one of claims 1 to 7, wherein the display unit includes auxiliary capacitance wiring common to the plurality of lines.

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