JP7420451B2 - Display device and display device driving method - Google Patents

Description

The present technology relates to a display device and a method of driving the display device.

In a display device such as a projection type liquid crystal display device, pixels are arranged two-dimensionally in a matrix, and a gate line is wired for each pixel row and a signal line is wired for each pixel column for this matrix-like pixel arrangement. A pixel array section, a vertical drive circuit that selects each pixel of this pixel array section row by row, and a horizontal drive circuit that writes a video signal to each pixel of the row selected by this vertical drive circuit via a signal line. The drive system is configured to adopt, for example, an active matrix system as a drive system.

In such a display device, prior to supplying a video signal to the signal line, a precharge signal (hereinafter referred to as "PsigG") of a halftone level (for example, gray level) of the signal line is supplied. A charging method is known. By supplying the precharge signal, the charging/discharging current due to the supply of the video signal can be suppressed, the occurrence of vertical stripes caused by the charging/discharging current can be eliminated, and the image quality can be improved.

However, if the precharge signal is set to a halftone level, vertical crosstalk may occur depending on the video pattern to be displayed, resulting in a loss of image quality. In order to reduce this vertical crosstalk, the level of the precharge signal may be set to a low potential (eg, black level).

In order to achieve both this vertical crosstalk reduction function and the vertical streak reduction function mentioned above, and to improve image quality, precharge signals of both low potential level and halftone level are used during the horizontal blanking period. A two-step precharge method has also been proposed in which the voltage is supplied to the signal line in two steps.

Furthermore, Patent Document 1 listed below describes a first period (supply of video signals to signal lines) in which a first voltage of a magnitude corresponding to the gradation to be displayed is supplied in order to respond to the recent trend toward higher resolution. A first pattern in which a low potential second voltage and a high potential second voltage are sequentially output during a second period (corresponding to a precharge period) before the second period (corresponding to a precharge period), and a second pattern in which only a high potential second voltage is output. A precharge method is disclosed in which a pattern can be selected according to the selection of a scanning line. As a result, one horizontal scanning period is shortened compared to the case of using only the first pattern, so that driving efficiency can be improved.

JP2017-187567A

However, for example, when the precharge method proposed in Patent Document 1 mentioned above is applied to a display device using a batch precharge method in which signal lines are precharged line by line, depending on the video pattern to be displayed, , a problem occurs in the displayed image.

Furthermore, in order to cope with the recent increase in the number of pixels and high-speed driving, it is desired to free up time by further improving driving efficiency.

Therefore, an object of the present technology is to provide a display device and a method for driving the display device that can perform high-quality and highly efficient display.

The first technique includes a vertical drive unit that sequentially selects pixels in a pixel array unit row by row;
It has a horizontal drive unit that supplies video signals to pixels selected in row units by the vertical drive unit,
A display device that performs precharging before supplying a video signal to each pixel by a horizontal drive unit,
During the horizontal blanking period, instead of the first horizontal line to which precharge signals of low potential level and halftone level are sequentially supplied, a precharge signal of both low potential level and halftone level is supplied intermittently during the horizontal blanking period. the second horizontal line drawn is inserted in a predetermined insertion pattern;
This is a display device in which a predetermined insertion pattern can be arbitrarily selected or set.

The second technique is to sequentially select pixels in a pixel array section in which a plurality of pixels are arranged in rows and columns by a vertical drive section,
A horizontal drive unit supplies a video signal to pixels selected row by row by a vertical drive unit,
A method for driving a display device that performs precharging before supplying a video signal to each pixel by a horizontal drive unit, the method comprising:
During the horizontal blanking period, instead of the first horizontal line to which precharge signals of low potential level and halftone level are sequentially supplied, a precharge signal of both low potential level and halftone level is supplied intermittently during the horizontal blanking period. the second horizontal line drawn is inserted in a predetermined insertion pattern;
This is a method of driving a display device that allows a predetermined insertion pattern to be arbitrarily selected or set.

According to the present technology, high-quality and highly efficient display can be performed.

FIG. 1 is a diagram showing an example of the configuration of a display device. FIG. 2 is a diagram showing a specific example of a configuration for supplying a precharge signal. FIG. 3 is a timing chart of an example of drive pulses without thinning out. FIG. 4 is a timing chart of an example of drive pulses with thinning. FIG. 5 is a diagram showing a specific example of a thinning insertion pattern. FIG. 6 is a diagram showing a specific example of a thinning insertion pattern. FIG. 7 is a diagram showing an example of how the extra time is used. FIG. 8 is a diagram showing an example of how the extra time is used. FIG. 9 is a diagram showing a specific example of a thinning distribution pattern. FIG. 10 is a diagram showing a specific example of a thinning distribution pattern. FIG. 11 is a diagram showing a specific example of a thinning distribution pattern. FIG. 12 is a diagram for explaining the relationship between the amount of change in potential and the amount of time. FIG. 13 is a diagram showing a specific example of a thinning insertion pattern. FIG. 14 is a diagram showing a modification of the configuration for supplying the precharge signal. FIG. 15 is a diagram showing a modification of the configuration for supplying the precharge signal. FIG. 16 is a diagram showing a specific example of a change pattern for changing the potential. FIG. 17 is a timing chart showing an example of the precharge period. FIG. 18 is a diagram for explaining a problem with a display image. FIG. 19 is a diagram for explaining the two-step precharge method. FIG. 20 is a diagram for explaining a problem with a displayed image.

Embodiments of the present technology will be described below with reference to the drawings. The explanation will be given in the following order.
<1. Problems with conventional display devices>
<2. First embodiment>
<3. Second embodiment>
<4. Modified example>
The embodiments and modified examples described below are preferred specific examples of the present technology, and the content of the present technology is not limited to these embodiments and modified examples.

<1. Problems with conventional display devices>
Problems of a conventional display device will be explained with reference to the drawings.
FIG. 17 is a timing chart showing an example of a precharge signal supply period (referred to as a "precharge period"). In a display device that uses a precharge method, as shown in FIG. 17, a precharge signal is supplied to the signal line in advance (the signal line is charging) is performed. By supplying the precharge signal in this manner, the charging/discharging current due to the supply of the video signal can be suppressed, the occurrence of vertical stripes due to the charging/discharging current can be eliminated, and the image quality can be improved.

However, when the precharge signal is set to a halftone level, the following problem occurs. FIG. 18 is a diagram for explaining a problem with a displayed image. In the display device described above, a TFT (Thin Film Transistor) is generally used as a pixel transistor. Therefore, for example, when displaying a black window pattern as shown in FIG. 18(A), as shown in FIG. 18(B), the signal line potential of the display area of the window pattern (A2 in FIG. ) is different from the signal line potential in the other gray areas (B2 or C2 in FIG. 18). This is because the pixel potential at the center A2 of the screen is not affected by the black potential, but the pixel potential at the top B2 of the screen changes toward the black potential due to the influence of the black potential, and the pixel potential at the bottom C2 of the screen is This is due to the fact that the held potential changes toward the white potential due to the influence of the black potential. As a result, the source-drain potential of the pixel transistor in both regions differs, resulting in a difference in the amount of current leakage in both regions. This symptom causes vertical crosstalk (hereinafter referred to as "vertical crosstalk"), which impairs image quality.

In order to reduce this vertical crosstalk, the level of the precharge signal may be set to a low potential (eg, black level). By writing a low potential level precharge signal (hereinafter referred to as "PsigB") to the signal line in advance in this way, the potential between the source and drain of the pixel transistor can be made constant over the entire pixel region. As a result, the amount of light leakage becomes uniform in all pixel regions, and, for example, vertical crosstalk when displaying the black window pattern described above can be reduced.

In order to achieve both this vertical crosstalk reduction function and the vertical streak reduction function described above, and to improve image quality, low potential levels and halftones are set during the horizontal blanking period as shown in Figure 19. A two-step precharge method has also been proposed in which both levels of precharge signals are supplied to the signal line in two steps.

Furthermore, in order to cope with the recent trend toward higher resolution, Patent Document 1 mentioned above describes a first period (supply of video signals to signal lines) in which a first voltage of a magnitude corresponding to the gray level to be displayed is supplied. A low potential second voltage (corresponding to the precharge signal PsigB) and a high potential second voltage (corresponding to the precharge signal PsigG) are sequentially output during the second period (corresponding to the precharge period) before the precharge period (corresponding to the precharge period). A precharge method is disclosed in which a first pattern and a second pattern that outputs only a high potential second voltage can be selected depending on the selection of a scanning line. As a result, one horizontal scanning period is shortened compared to the case of using only the first pattern, so that driving efficiency can be improved.

However, for example, when the precharge method proposed in Patent Document 1 mentioned above is applied to a display device using a batch precharge method in which signal lines are precharged line by line, depending on the video pattern to be displayed, , a problem occurs in the displayed image. FIG. 20 is a diagram for explaining a problem with a displayed image. As shown in the figure, depending on the video pattern to be displayed, the precharge period may be insufficient, resulting in a difference in the potential reached by precharge for each horizontal line. As a result, there is a concern that lateral (horizontal) crosstalk (hereinafter referred to as "lateral crosstalk") may occur, as shown in FIG. 20(A).

In other words, it is ideal that the precharge period is a period during which the precharge signal reaches a desired potential, but as shown in FIG. When the period is shortened, depending on the video pattern to be displayed, when the precharge signal PsigB is thinned out, a difference occurs in the potential of the precharge signal PsigG between the window display line and the window non-display line, and the video signal A difference also occurs in the potential reached. This is because if the precharge signal PsigB is simply thinned out, the precharge period will be insufficient in the thinned out portion, and the precharge signal PsigG cannot be charged to the desired potential, making it impossible for the video signal to reach the desired potential. do. As a result, depending on the pattern to be displayed, there is a concern that this unbalance in the reached potentials may be visually recognized as lateral crosstalk. Furthermore, there is a concern about insufficient charging of the signal line due to insufficient charging of the precharge signal PsigG.
The present technology solves the above-mentioned problems.

<2. First embodiment>
[Example of configuration of display device]
FIG. 1 is a diagram illustrating a configuration example of a display device (display device 1) according to a first embodiment of the present technology. As shown in the figure, the display device 1 is an active matrix liquid crystal display device, and includes a pixel array section 2 in which pixels PX are arranged in row and column directions, and a peripheral area for driving each pixel PX of this pixel array section 2. A circuit. The peripheral circuits include vertical drive circuits 3A and 3B as vertical drive sections, and a horizontal drive circuit 4 and precharge control circuit 5 as horizontal drive sections.

For example, as shown in the figure, these peripheral circuits are formed on a substrate (hereinafter referred to as a "liquid crystal panel") P, and an image is transmitted from the outside of the liquid crystal panel P via a connection terminal T. The signal Vsig (1 to n) is supplied to the horizontal drive circuit 4, and the precharge signal Psig is further supplied to the precharge control circuit 5. Various driving pulses (control signals for driving) are also supplied from the outside of the liquid crystal panel P. Note that these signals may be generated inside the liquid crystal panel P.

The pixel array section 2 has a structure in which pixels PX including liquid crystal cells, which are electro-optical elements, are two-dimensionally arranged in a matrix (m rows, n columns). For this pixel array of m rows and n columns, gate lines 6 (6(1), 6(2), ..., 6(m)) are wired for each pixel row, and signal lines 7 (7) are wired for each pixel column. (1), 7(2),..., 7(n)) are wired (m and n are natural numbers). Both ends of the gate line 6 are connected to the output ends of the corresponding rows of the vertical drive circuit 3A and the vertical drive circuit 3B. One end of the signal line 7 is connected to the output end of the corresponding column of the horizontal drive circuit 4. The other end of the signal line 7 is connected to the output end of the corresponding column of the precharge control circuit 5.

The vertical drive circuits 3A and 3B sequentially select each pixel PX of the pixel array section 2 on a row-by-row basis. Note that in this embodiment, a double-sided drive configuration in which the pixel array section 2 is arranged so as to be sandwiched between the vertical drive circuit 3A and the vertical drive circuit 3B is illustrated, but a one-sided drive structure in which the pixel array section 2 is arranged only on one side of the pixel array section 2 is illustrated. It may also be a drive configuration.

The horizontal drive circuit 4 is for supplying a video signal to each pixel PX selected on a row-by-row basis by the vertical drive circuits 3A and 3B. The precharge control circuit 5 is for supplying a precharge signal Psig before the horizontal drive circuit 4 supplies a video signal to each pixel PX.

FIG. 2 is a diagram showing a specific example of a configuration for supplying the precharge signal Psig. As shown in FIG. 2, the pixel (pixel circuit) PX includes, for example, a pixel transistor Tr formed of a TFT (Thin Film Transistor), a storage capacitor 9, and a liquid crystal cell. Note that the liquid crystal cell is omitted here to simplify the drawing.

The pixel transistor Tr has a gate electrode connected to the gate line 6 of the corresponding pixel row, and a source electrode connected to the signal line 7 of the corresponding pixel column. Furthermore, one electrode of the storage capacitor 9 and a pixel electrode (not shown) of the liquid crystal cell are connected to the drain electrode of the pixel transistor Tr. The holding capacitor 9 holds the pixel potential written by the pixel transistor Tr. Note that the other electrode of the storage capacitor 9 and the counter electrode (not shown) of the liquid crystal cell are, for example, commonly connected to the CS line 10 between each pixel. A predetermined voltage is applied as a common voltage Vcom to the other electrode of the storage capacitor 9 and the opposing electrode of the liquid crystal cell via this CS line 10. Note that the connection between the other electrode of the storage capacitor 9 and the counter electrode of the liquid crystal cell is not limited to such a common connection, but may be through independent supply lines.

On the other hand, the horizontal drive circuit 4 described above includes an analog switch HSW that controls charging and discharging of the video signal Vsig to each signal line 7. As the analog switch HSW, for example, a switch element such as an NMOS switch using an N-channel MOS transistor can be used. One end of the analog switch HSW is connected to a supply line for the video signal Vsig, and the other end is connected to one end of the signal line 7. Furthermore, a control HSW gate pulse is supplied to the analog switch HSW. Then, the analog switch HSW controls the conduction state (conduction/non-conduction) between the supply line of the video signal Vsig and the signal line 7 according to this HSW gate pulse. By being controlled to be conductive, the video signal Vsig is supplied to the signal line 7.

On the other hand, the precharge control circuit 5 described above includes an analog switch PSW that controls charging and discharging of the precharge signal Psig to each signal line 7. As the analog switch PSW, for example, a switch element such as an NMOS switch using an N-channel MOS transistor can be used. One end of the analog switch PSW is connected to the supply line of the precharge signal Psig, and the other end is connected to the other end of the signal line 7. Further, a PCG pulse for control is supplied to the analog switch PSW. This PCG pulse is a signal that determines the period during which the precharge signal Psig is supplied to the signal line 7. The analog switch PSW controls the conduction state (conduction/non-conduction) between the supply line of the precharge signal Psig and the signal line 7 according to this PCG pulse. By being controlled to be conductive, a precharge signal Psig is supplied to the signal line 7. Note that the analog switch PSW is specifically controlled so that the precharge signal Psig is supplied to the signal line 7 during the horizontal blanking period.

Specifically, the analog switch PSW responds to a PCG pulse externally applied, for example, every horizontal period (1H), before the horizontal drive circuit 4 supplies the video signal Vsig to each signal line 7. By turning on all at once, the precharge signal Psig supplied from the outside is supplied to each signal line 7 at once. Note that although a batch precharge method in which each signal line 7 is precharged at once is exemplified here, a point-sequential precharge method in which the signal lines 7 are precharged in order may be used.

This precharge signal Psig corresponds to a two-step precharge method, and includes a precharge signal PsigB at a low potential level (for example, below the black level) and a halftone level (for example, gray level) of the video signal Vsig. It has a precharge signal PsigG of (level). When the precharge signal Psig is supplied to the signal line 7, the precharge signal PsigB and the precharge signal PsigG are sequentially supplied. By adopting the two-step precharge method in this way, as described above, by supplying the precharge signal PsigG at the halftone level, it is possible to reduce vertical streaks and improve the image quality by improving the image quality. By supplying the precharge signal PsigB at a low potential level, vertical crosstalk can be reduced and image quality can be improved.

The present embodiment is characterized in that the precharge signal Psig is not supplied to all horizontal lines, but is thinned out according to a predetermined thinning insertion pattern (details will be described later).

FIG. 3 is a timing chart of an example of drive pulses without thinning out. FIG. 4 is a timing chart of an example of drive pulses with thinning. Regarding the horizontal line to which the precharge signal Psig is supplied to the signal line 7, as shown in FIG. 3, the PRG pulse is at a high level in the first half of the precharge period and at a low level in the second half. This PRG pulse is a signal that determines the supply period of the precharge signal PsigB. The PRG pulse switches between the precharge signal PsigB at a low potential level and the precharge signal PsigG at an intermediate level. When the PRG pulse is at a high level, a precharge signal PsigB at a low potential level is selected, and when the PRG pulse is at a low level, a precharge signal PsigG at a halftone level is selected. The aforementioned precharge control circuit 5 (see FIG. 1) supplies the final precharge signal Psig to the signal line 7 at a predetermined timing during the horizontal blanking period via the analog switch PSW.

In the illustrated example, after the end of the supply of the video signal Vsig synchronized with the horizontal clock signal HCK, the enable signal ENB is switched after a period A has elapsed, and the clock signal VCK is switched after a period B has elapsed from the switching of the enable signal ENB. The PCG pulse and PRG pulse are switched from low level to high level in synchronization with this clock signal VCK. The PRG pulse is switched to a low level after a period C has elapsed since this switching, and the PCG pulse has been switched to a low level after a period D has elapsed since this switching. Then, the next video signal Vsig is supplied after a period of E has elapsed since the switching. In other words, the horizontal blanking period requires the sum of all periods A to E.

On the other hand, for horizontal lines where the precharge signal Psig is not supplied to the signal line 7 due to thinning, the PRG pulse and the PCG pulse are not output, as shown in FIG. Therefore, in the illustrated example, the enable signal ENB is switched after a period F has elapsed since the switching of the clock signal VCK, and the next video signal Vsig is supplied after a period G has elapsed since the switching. In other words, the horizontal blanking period requires the sum of all the periods A, B, F, and G. Note that F+G<C+D+E.

In this way, the horizontal line where the supply of the precharge signal Psig has been thinned out can shorten the horizontal blanking period compared to the horizontal line where the supply of the precharge signal Psig has not been thinned out.

[Thinning insertion pattern]
Here, the insertion pattern for thinning out the supply of the precharge signal Psig mentioned above will be explained. 5 and 6 are diagrams showing specific examples of thinning insertion patterns. Although FIG. 5 schematically shows the lengths of the horizontal video period and the horizontal blanking period, FIG. 6 only shows the arrangement of the horizontal blanking periods in each horizontal line. Further, in each figure, a horizontal B period (a) indicates a horizontal blanking period in which thinning is not inserted, and a horizontal B period (b) indicates a horizontal blanking period in which thinning is inserted. Note that for ease of illustration, the number of horizontal lines is 12.

In the example shown in FIG. 5, thinning is inserted regularly. That is, one horizontal line out of two horizontal lines is thinned out periodically. As mentioned above, the horizontal blanking period (horizontal B period (b)) in which thinning of the precharge signal Psig is inserted is different from the horizontal blanking period (horizontal B period (a)) in which thinning is not inserted. The length of the period is shortened. In other words, the horizontal blanking period can be shortened by inserting thinning.

Note that the thinning insertion pattern is not limited to thinning out every line as described above, and may be, for example, as shown in FIG. 6. In the example shown in FIG. 6A, two of the three horizontal lines are periodically thinned out. In this way, the thinning ratio is not particularly limited, and is appropriately set in advance depending on the display state and the like. Note that this ratio may be configured to be settable to an arbitrary value.

Further, the thinning insertion pattern is not limited to periodic thinning, and may be the one illustrated in FIG. 6(B) and FIG. 6(C). In the example shown in FIG. 6(B), groups of horizontal lines (the latter 8 horizontal lines in the example shown in the figure) other than the four consecutive horizontal lines (the first four horizontal lines in the example shown in the figure) among the total 12 horizontal lines are shown. We are doing thinning out. Further, in the example shown in FIG. 6(C), thinning is irregularly scattered. In the examples shown in FIGS. 6A to 6C, the overall thinning ratio is 8/12.

Note that although the insertion pattern of thinning out in units of horizontal lines is illustrated here, the present invention is not limited to this, and a plurality of consecutive horizontal lines may be made into one group, and the above-described insertion pattern of thinning out may be applied in units of groups. Furthermore, these insertion patterns may be combined.

As described above, the thinning insertion pattern is set as appropriate depending on the display state and the like. Note that this insertion pattern may be arbitrarily selectable or may be configured to be arbitrarily set. In any case, by thinning out the supply of the precharge signal Psig, the horizontal blanking period can be shortened, making it possible to cope with an increase in the number of pixels and high-speed driving. Furthermore, the time saved by the shortening can be effectively utilized. For example, in order to make effective use of this extra time, the horizontal drive circuit 4 and the precharge control circuit 5 vary the length of the horizontal line so that the vertical period after thinning is the same as the vertical period when no thinning is performed. do. In this way, by keeping the vertical period unchanged (possible even without reduction) even after thinning, it is possible to use the system configuration when thinning is not performed.

FIG. 7 and FIG. 8 are diagrams showing examples of how the extra time is used. Note that FIGS. 7 and 8 are for the case where one horizontal line out of the two horizontal lines described with reference to FIG. 5 is thinned out periodically. For example, as shown in FIG. 7A, by allocating the time saved by reducing the horizontal blanking period to the horizontal video period (a) and making it a longer horizontal video period (b), the supply period of the video signal Vsig is can be made long enough to provide good image quality. As mentioned above, the allocation of this extra time is, for example, as shown in FIG. a)) and the vertical period when thinning out, that is, horizontal line L2 (horizontal video period (b) + horizontal B period (a)) and horizontal line L3 (horizontal video period (b) )+horizontal B period (b)) is performed so that the vertical period is the same. In addition, as shown in FIG. 8(A), by allocating the extra time to the horizontal B period (a) and making it a longer horizontal blanking period (horizontal B period (c)), even high-speed multi-pixel driving is possible. A precharge period can be secured. Regarding the allocation of this spare time, for example, as shown in FIG. 8(B), there is a vertical period when no thinning is performed, that is, a vertical period consisting of only the horizontal line L1, and a vertical period when thinning is performed. , that is, a vertical period consisting of two horizontal lines L4 (horizontal video period (a) + horizontal B period (c)) and horizontal line L5 (horizontal video period (a) + horizontal B period (b)). are done so that they are the same.

In addition, by thinning out the supply of the precharge signal Psig, there is no need to charge and discharge the signal line group, which is arranged as many times as the horizontal resolution and have a relatively large capacity, in a short time, and the frequency of charging and discharging is also reduced. , the total system current consumption and heat generation of the display device 1 can be reduced compared to the case where thinning is not performed. Furthermore, since the required current is reduced, there is no need to add new parts, contributing to a reduction in the number of set parts. In addition, in this method, the clock period is distributed, and a radiation reduction effect is expected. Furthermore, since the precharge signal PsigB at a low potential level intentionally causes SD leakage (leakage of charge in the source direction to the drain) of the pixel transistor Tr, supplying the precharge signal PsigB at a low potential level causes the SD leakage of the pixel transistor Tr to be maintained. However, in this embodiment, by thinning out the supply of the precharge signal PsigB and the precharge signal PsigG, it is possible to prevent the holding potential from decreasing, thereby preventing deterioration of optical properties such as brightness and contrast. You can choose not to invite them. Furthermore, by thinning out the supply of the precharge signal Psig, the number of potential fluctuations of the signal line 7 is reduced, so the occurrence of noise caused by the precharge signal Psig can be reduced, and the image quality can be improved. . Furthermore, since both the precharge signal PsigB and the precharge signal PsigG are thinned out, as mentioned above, it is possible to prevent the occurrence of horizontal crosstalk that would occur by thinning out only the precharge signal PsigB, and to improve the image quality. I can do it.

[Thinning distribution pattern]
Note that in this embodiment, the precharge signal thinning/insertion period is distributed for each vertical period (for example, field). 9 to 11 are diagrams showing specific examples of thinning distribution patterns. Note that in FIG. 9, FIG. 9A shows a case where thinning is not distributed, and FIG. 9B is a case where thinning is distributed. In the example shown in FIG. 9, two horizontal lines out of three horizontal lines are periodically thinned out in each of vertical periods (N), vertical periods (N+1), vertical periods (N+2), . . . . In the case where thinning is not distributed as shown in FIG. 9A, thinning is performed in the same pattern in any vertical period. On the other hand, in the example shown in FIG. 9B, horizontal lines that are not thinned out are not continuous in adjacent vertical periods. As a result, the thinning insertion period is distributed.

In addition, in the example shown in FIG. 10, in each of the vertical period (N), vertical period (N+1), vertical period (N+2), etc., horizontal lines other than consecutive 4 horizontal lines among the total 12 horizontal lines are grouped. are being thinned out. Then, the horizontal lines in which no thinning is inserted are discontinued in adjacent vertical periods, so that the thinning insertion periods are dispersed. Furthermore, in the example shown in FIG. 11, thinning is performed irregularly in each of the vertical periods (N), vertical periods (N+1), vertical periods (N+2), etc., and the horizontal line without thinning is inserted. , the thinning insertion periods are distributed so that they are not consecutive in adjacent vertical periods.

Note that if the number of horizontal lines on which thinning is not inserted is greater than the number of horizontal lines on which thinning is inserted, the horizontal lines on which thinning is inserted are not consecutive in adjacent vertical periods. Good too. Further, it may be configured such that it is possible to arbitrarily select whether or not to perform the dispersion for each vertical period. Further, the thinning is not limited to being distributed every vertical period, but the thinning may be distributed every several vertical periods, or the thinning insertion pattern may be changed every vertical period. In any case, by distributing the thinning of the supply of the precharge signal Psig for each vertical period, thinning can be inserted evenly and in a well-balanced manner. In this way, by eliminating non-uniformity between thinned lines and non-thinned lines, it is possible to provide uniform and high quality image quality.

[Creating time due to differences in potential change]
Furthermore, in this embodiment, for horizontal lines in which the supply of precharge signal Psig is not thinned out, a precharge signal PsigB of a low potential level is replaced with a precharge signal PsigB of a low potential level, and the low potential level is the amount of potential change. Further time is saved by supplying a precharge signal (hereinafter referred to as "PsigB2") with a different potential level.

FIG. 12 is a diagram for explaining the relationship between the amount of change in potential and the amount of time. FIG. 12(A) shows a case where a normal precharge signal PsigB is supplied, and FIG. 12(B) shows a case where a precharge signal PsigB2 whose potential change is smaller than the normal precharge signal PsigB is supplied. represents. As shown in the figure, the supply period of the precharge signal B2, which has a small amount of potential change, is shorter than the supply period of the precharge signal PsigB. As a result, the entire precharge period can also be shortened (precharge signal PsigB+PsigG>precharge signal PsigB2+PsigG), and further time can be saved. Note that the predetermined change pattern can be similar to the thinning insertion pattern described above. In this way, by making the amount of potential change of the precharge signal Psig shallow for a certain period of time, the horizontal blanking period can be shortened, and it is possible to cope with a further increase in the number of pixels and high-speed driving.

<3. Second embodiment>
Next, a second embodiment of the present technology will be described. This embodiment is different from the first embodiment described above in the thinning insertion pattern. Note that the configuration of the display device in this embodiment is similar to the display device 1 described in the above-described first embodiment, and the description thereof will be omitted here.

[Thinning insertion pattern]
Incidentally, in a liquid crystal display device, for example, an AC driving method is used in which the polarity of a signal voltage applied to a pixel electrode of a liquid crystal cell with respect to a potential of a counter electrode of the liquid crystal cell is reversed at a predetermined period (for example, every field). It has been adopted. In this embodiment, when displaying the video signal Vsig whose polarity is inverted at a predetermined period, the precharge signal PsigG is supplied to the first horizontal line in the vertical period after the polarity inversion. The supply of the precharge signal Psig is thinned out.

FIG. 13 is a diagram showing a specific example of the thinning insertion pattern in this embodiment. As shown in the figure, specifically, the precharge signal Psig is supplied only to the first horizontal line in the vertical period, and the supply of the precharge signal Psig to other horizontal lines is thinned out. There is. As a result, extreme signal line potential fluctuations at the time of polarity reversal can be alleviated, and even if the supply of the precharge signal Psig is thinned out on other horizontal lines, the horizontal period (less period) during which the precharge signal Psig is thinned out Good image quality can also be provided.

<4. Modified example>
Although the embodiments of the present technology have been specifically described above, the content of the present technology is not limited to the embodiments described above, and various modifications are possible.

[Modified example of configuration of display device]
In the first embodiment described above (the second embodiment is similar), the analog switch PSW and the analog switch HSW are provided independently, and the analog switch PSW is arranged on the opposite side from the analog switch HSW. (See Figure 2). In other words, the precharge signal Psig was supplied from the side opposite to the analog switch HSW. However, the analog switch PSW is not limited to being provided in this manner.

14 and 15 are diagrams showing modified examples of the configuration for supplying the precharge signal Psig. For example, as shown in FIG. 14, an analog switch PSW may be placed on the analog switch HSW side. In other words, the configuration may be such that the precharge signal Psig is supplied from the analog switch HSW side. Alternatively, as shown in FIG. 15, the analog switch PSW may be used in common with the analog switch HSW, and the precharge signal Psig may be supplied from the analog switch HSW side.

[Modified example of making time]
Furthermore, in the first and second embodiments described above, the horizontal blanking period is shortened and time is saved by thinning out the supply of the precharge signal Psig. Alternatively, as explained with reference to FIG. 12, the time may be saved by reducing the amount of change in the potential of the precharge signal Psig.

FIG. 16 is a diagram showing a specific example of a change pattern for changing the potential. In FIG. 16, the length of the horizontal blanking period in which the precharge signal PsigB and the precharge signal PsigG are sequentially supplied is expressed as "PsigB normal", and the length of the horizontal blanking period in which the precharge signal PsigB2 and the precharge signal PsigG are sequentially supplied is expressed as "PsigB normal". The length of the blanking period is expressed as "shallow PsigB".

In the example shown in FIG. 16, the precharge signal PsigB is regularly replaced with the precharge signal PsigB2, which has a smaller amount of change in potential (has a shallower waveform) than the precharge signal PsigB. In other words, one of the two horizontal lines is changed periodically. As mentioned above, the horizontal blanking period (Shallow PsigB) in which PsigB2 is supplied instead of the precharge signal PsigB is shorter than the horizontal blanking period (PsigB normal) in which the precharge signal PsigB is normally supplied. The length is shortened. In other words, the horizontal blanking period can be shortened by making the amount of potential change of the precharge signal Psig shallower for a certain period of time.

Note that the change pattern to the precharge signal PsigB2 is not limited to changing for each row as described above, and may be set as appropriate, as in the case of thinning described above, and the pattern described as thinning described above is not limited to the change pattern for each line. It can be applied to all parts.

DESCRIPTION OF SYMBOLS 1... Display device, 2... Pixel array part, 3A, 3B... Vertical drive circuit, 4... Horizontal drive circuit, 5... Precharge control circuit, 6... Gate line, 7 ...Signal line, HSW...analog switch, PSW...analog switch, PX...pixel

Claims (7)

a pixel array section in which a plurality of pixels are arranged in a matrix;
a vertical drive unit that sequentially selects pixels of the pixel array unit row by row;
a horizontal drive unit that supplies a video signal to the pixels selected by the vertical drive unit in units of rows;
A display device that performs precharging prior to supplying a video signal to each pixel by the horizontal drive unit,
In place of the first horizontal line to which precharge signals of low potential level and halftone level are sequentially supplied during the horizontal blanking period, a precharge signal of both the low potential level and halftone level is supplied during the horizontal blanking period. inserting a second horizontal line to be thinned out in a predetermined insertion pattern;
A display device in which the predetermined insertion pattern can be arbitrarily selected or set. The display device according to claim 1, wherein the insertion pattern thins out the supply of the precharge signal at a predetermined cycle or irregularly based on a predetermined setting. The display device according to claim 1 , wherein the insertion pattern disperses the second horizontal line every vertical period. 4. In the first horizontal line, instead of the precharge signal at the low potential level, a precharge signal at a potential level with a smaller amount of change in potential than the low potential level is supplied. display device. In the insertion pattern, when displaying a video signal whose polarity is inverted at a predetermined period, the second horizontal line is selected as a horizontal line other than the first horizontal line in the vertical period after the polarity inversion. The display device according to claim 1. The display device according to any one of claims 1 to 5, wherein the length of the horizontal line is varied, and the vertical period after the thinning is made the same as the vertical period when the thinning is not performed. A vertical drive section sequentially selects pixels in a pixel array section in which multiple pixels are arranged in rows and columns, row by row,
supplying a video signal by a horizontal drive unit to the pixels selected in row units by the vertical drive unit;
A method for driving a display device that performs precharging before the horizontal driving section supplies a video signal to each pixel , the method comprising:
In place of the first horizontal line to which precharge signals of low potential level and halftone level are sequentially supplied during the horizontal blanking period, a precharge signal of both the low potential level and halftone level is supplied during the horizontal blanking period. inserting a second horizontal line to be thinned out in a predetermined insertion pattern;
A method for driving a display device that allows the predetermined insertion pattern to be arbitrarily selected or set.

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