WO2006092977A1

WO2006092977A1 - Display and displaying method

Info

Publication number: WO2006092977A1
Application number: PCT/JP2006/303009
Authority: WO
Inventors: Makoto Shiomi
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2005-03-04
Filing date: 2006-02-21
Publication date: 2006-09-08

Abstract

The invention relates to a display of a hold type. One frame period which is the period during which an image of one screen is displayed is divided into a dark display period during which a relatively dark image is displayed and a bright display period during which a relatively bright image is displayed. During the dark display period, scanning signal lines (GL1, GL2, GL3,...) are continuously driven twice for a period corresponding to a third of a conventional one horizontal scanning period. During the dark display period, two of the scanning signal lines (GL1, GL2, GL3,...) are driven at a time. The gradation for creating a video signal so that an average luminance of the luminances to normally appear at two pixel forming portions disposed at the intersections of the two scanning signal lines simultaneously driven and a video signal appears at the two pixel forming portions is computed.

Description

Specification

Display device and display method

Technical field

The present invention relates to a hold-type display device, and more particularly to a hold-type display device that displays an image by dividing one frame period into a plurality of subframe periods and a display method thereof.

Background art

Conventionally, as a display device, for example, an impulse-type display device such as a CRT (Cathode Ray Tube) and a hold-type display device such as an LCD (Liquid Crystal Display) It has been known. In an impulse-type display device, focusing on individual pixels, a lighting period in which an image is displayed and a light-out period in which no image is displayed are alternately repeated. For example, even when a moving image is displayed, a light-off period is inserted when an image for one screen is rewritten, so that an afterimage of an object moving in human vision does not occur. For this reason, the background and the object can be clearly distinguished, and the video can be viewed without a sense of incongruity. On the other hand, in the hold-type display device, the luminance for each pixel is held during a frame period that is a cycle of rewriting an image for one screen. When a moving image is displayed on the hold-type display device, an afterimage of a moving object is generated in human vision. Specifically, the moving object is visually recognized with a blurred outline. Such a phenomenon is called “motion blur” and is considered to be caused by the tracking ability of human eyes. In a hold-type display device, such a motion blur occurs when displaying a moving image. Therefore, an impulse-type display device is generally used for a display such as a television that mainly displays a moving image. . However, in recent years, there has been a strong demand for lightweight displays and thin displays for displays such as televisions, and the adoption of hold-type display devices that are easy to reduce the thickness of such displays is rapidly progressing. RU

[0003] In addition, regarding the hold-type display device, image quality deterioration due to the low response speed of the display element has also been a problem. Driving to suppress this image quality degradation As a method, overshoot driving is known (for example, Japanese Unexamined Patent Publication No. 2004-233949). Overshoot drive is a drive voltage higher than the gradation voltage for the input image signal of the current frame, which is determined in advance, depending on the combination of the input image signal of the previous frame and the input image signal of the current frame. This is a driving method that supplies a liquid crystal display panel with a driving voltage lower than the gradation voltage for the input image signal of the determined current frame.

On the other hand, in order to suppress the motion blur described above, the frame period is divided into a period during which an image is displayed (hereinafter referred to as “display period”) and a period during which no image is displayed (hereinafter referred to as “non-display period”). There have been proposed display devices that perform image display using divided pseudo impulse driving (hereinafter referred to as “pseudo impulse driving”) (for example, Japanese Unexamined Patent Publication No. 2002-23707 or Japanese Unexamined Patent Publication 2003). — 22061 publication). FIG. 14 is a signal waveform diagram for explaining a method of driving such a display device. Note that the display device includes a plurality (m) of scanning signal lines GLl to GLm (hereinafter also referred to as “first to m-th scanning signal lines”). As shown in FIG. 14, when the gate clock signal GCK pulse is generated first after the gate start pulse signal GSP pulse is generated, the scanning signal supplied to the scanning signal line GL1 in the first row becomes high level. . The pulse width of the gate clock signal GCK corresponds to approximately one half of the conventional horizontal scanning period, and the scanning signal supplied to the scanning signal line GL1 in the first row is maintained at a high level only during that period. After that, according to the generation of the pulse of the gate clock signal GCK, the scanning signals supplied to the second and subsequent scanning signal lines GL2, GL3,... The level is maintained only for a period corresponding to approximately one half of the period. In this way, after the scanning signals supplied to all the scanning signal lines become high level for a period corresponding to approximately one half of the conventional horizontal scanning period, the gate start pulse signal GSP is generated again. To do. Then, in response to the generation of the pulse of the gate clock signal GCK, the scanning signals supplied to all the scanning signal lines again sequentially become high level, which corresponds to approximately one half of the conventional one horizontal scanning period. The high level is maintained only during the period. As described above, one frame period (If) is divided into two periods having the same length (If Z2). Specifically, as shown in FIG. 15, one frame period is divided into two periods called subframes, and one of the subframes is divided. Image display is performed only during the frame period (display period), and image display is not performed during the other subframe period (non-display period). As a result, when the image for one screen is rewritten, a black image is inserted between the preceding image and the succeeding image. As a result, afterimages of moving objects in human vision are not generated, and motion blur is suppressed.

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-233949

Patent Document 2: Japanese Patent Laid-Open No. 2002-23707

Patent Document 3: Japanese Patent Laid-Open No. 2003-22061

Disclosure of the invention

Problems to be solved by the invention

[0005] However, when image display is performed by the above-described pseudo-inners drive, the length of one frame period is the same as the conventional one, so the length of the display period is shorter than the conventional one. In other words, the time for charging the pixel capacitance corresponding to each pixel is shorter than before. In the example shown in FIG. 14 and FIG. 15, one frame period is divided into two subframe periods of equal length. Therefore, the time for charging the pixel capacity is about half of the conventional time, and the force is not secured. For this reason, the pixel capacitance is not sufficiently charged, and the luminance that should be displayed for each pixel may not appear. As a result, when moving images are displayed, the image quality deteriorates. In addition, overshoot driving as described above has been proposed to suppress image quality deterioration due to the low response speed of the display element, and it is not easy to determine the signal level for force driving.

[0006] Therefore, the present invention realizes a hold-type display device that can effectively suppress deterioration in image quality due to insufficient charging of a pixel capacity while suppressing motion blur when displaying a moving image. For the purpose.

Means for solving the problem

[0007] A first aspect of the present invention provides a plurality of video signal lines for transmitting a video signal based on an image to be displayed, a plurality of scanning signal lines intersecting the plurality of video signal lines, and the plurality of video signal lines. A plurality of pixel forming portions arranged in a matrix corresponding to intersections of a plurality of video signal lines and the plurality of scanning signal lines, and driving the video signals and the plurality of scanning signal lines. A display control circuit for outputting a scanning signal line driving timing signal for operating

The frame period, which is the period during which an image for one screen is displayed, is relatively low and the brightness is displayed 1 or more dark display periods and the relatively high brightness display is performed 1 or more bright display periods And displaying the luminance determined based on the gradation of the image for the one screen in each of the one or more dark display periods and the one or more bright display periods. A display device that displays an image for the one screen in the one or more dark display periods and the one or more bright display periods,

One dark display period is set to be shorter than one bright display period.

[0008] A second aspect of the present invention is the first aspect of the present invention,

The display control circuit outputs the scanning signal line driving timing signal so that the plurality of scanning signal lines are simultaneously driven by a predetermined number of 2 or more during the dark display period.

[0009] A third aspect of the present invention is the second aspect of the present invention,

The two or more predetermined number of scanning signal lines driven simultaneously are a plurality of scanning signal lines arranged continuously in the extending direction of the plurality of video signal lines,

Each scanning signal line is continuously driven a plurality of times during the dark display period.

[0010] A fourth aspect of the present invention is the second aspect of the present invention,

The two or more predetermined number of scanning signal lines driven simultaneously are a plurality of scanning signal lines selected every other one of the plurality of scanning signal lines,

Each scanning signal line is driven a plurality of times during the dark display period,

The display control circuit and the scanning signal line driving timing signal are arranged so that the polarity of the video signal applied to each video signal line is the same in all the periods in which each scanning signal line is driven a plurality of times. The video signal is output.

[0011] According to a fifth aspect of the present invention, in the second aspect,

The display control circuit is arranged corresponding to an intersection of the two or more predetermined number of scanning signal lines and each video signal line in a period in which the two or more predetermined number of scanning signal lines are simultaneously driven. The brightness of the combined pixel formation unit group that is a plurality of pixel formation units The video signal so as to have an average value of luminance to be displayed in the dark display period determined based on the gradation of the image for one screen for a plurality of pixel forming portions included in the combined pixel forming portion group. Is output.

[0012] A sixth aspect of the present invention, in the fifth aspect,

The display control circuit includes a dark display period gradation calculation circuit for calculating a gradation of the combined pixel formation unit group in the dark display period,

The dark display period gradation calculation circuit includes:

Based on the luminance to be displayed in the dark display period determined based on the gradation of the image for one screen for each pixel forming unit, a plurality of pixels included in the combined pixel forming unit group Calculate the average brightness of the formation part,

Based on the average value, the gradation of the combined pixel formation unit group in the dark display period is calculated.

[0013] A seventh aspect of the present invention, in a sixth aspect,

The dark display period gradation calculation circuit performs a predetermined correction so as to increase the charging rate of each pixel formation part when calculating the gradation of the combined pixel formation part group in the dark display period. A correction circuit is further included.

[0014] An eighth aspect of the present invention is the second aspect,

The display control circuit is arranged corresponding to an intersection of the two or more predetermined number of scanning signal lines and each video signal line in a period in which the two or more predetermined number of scanning signal lines are simultaneously driven. The one screen with respect to one predetermined pixel forming unit among the plurality of pixel forming units included in the combined pixel forming unit group in which the luminance of the combined pixel forming unit group, which is a plurality of pixel forming units, is determined. The video signal is output so that the luminance should be displayed during the dark display period determined based on the gradation of the minute image.

[0015] According to a ninth aspect of the present invention, in the first aspect,

In the frame period, the one or more dark display periods precede the one or more bright display periods in time.

[0016] A tenth aspect of the present invention provides a plurality of video signal lines for transmitting a video signal based on an image to be displayed, a plurality of scanning signal lines intersecting with the plurality of video signal lines, A display method comprising: a plurality of pixel forming portions arranged in a matrix corresponding to intersections of a plurality of video signal lines and the plurality of scanning signal lines, respectively.

The frame period, which is the period during which an image for one screen is displayed, is set to one or more dark display periods in which relatively low brightness is displayed, and each period is longer than one dark display period. It is divided into one or more bright display periods in which a relatively high luminance display is performed.

[0017] An eleventh aspect of the present invention is the tenth aspect,

A display control step of outputting the video signal and a scanning signal line driving timing signal for driving the plurality of scanning signal lines;

In the display control step, in the dark display period, the scanning signal line driving timing signal is output so that the plurality of scanning signal lines are simultaneously driven by a predetermined number of two or more. .

The invention's effect

[0018] According to the first aspect of the present invention, one frame period, which is a period during which an image for one screen is displayed, is relatively relative to one or more dark display periods during which a relatively dark image is displayed. It is composed of one or more bright display periods in which a bright image is displayed. These one or more dark display periods and one or more bright display periods are alternately repeated. For this reason, a dark image is inserted when the image for one screen is rewritten. As a result, an afterimage of an object moving in human vision is not generated, and motion blur is suppressed. The 1-light display period is set longer than the 1-dark display period. For this reason, sufficient time for charging the pixel capacitance of each pixel formation portion is ensured in the bright display period. As a result, insufficient charging in the bright display period with a high contribution to the image visually recognized by human beings is suppressed, and it is possible to suppress an uncomfortable feeling in human vision due to the displayed images.

According to the second aspect of the present invention, a plurality of scanning signal lines are driven simultaneously during the dark display period. For this reason, the time required for driving all the scanning signal lines is shortened as compared with the conventional configuration in which the scanning signal lines are driven one by one. As a result, the 1-light display period can be set longer than the 1-dark display period.

[0020] According to the third aspect of the present invention, a plurality of scanning signal lines driven simultaneously in the dark display period Are arranged consecutively. For this reason, the plurality of pixel forming portions included in the combined pixel forming portion group are arranged close to each other. When the luminance of the combined pixel forming unit group is determined based on the luminance of the plurality of pixel forming units included in the combined pixel forming unit group, since the plurality of pixel forming units are arranged close to each other, the luminance is given to the display image. The impact will be small. This effectively suppresses motion blur while suppressing image quality deterioration.

[0021] According to the fourth aspect of the present invention, the polarity of the video signal applied to each video signal line is the same in all the periods in which each scanning signal line is driven a plurality of times. For this reason, even during the dark display period, each pixel forming portion is effectively charged.

[0022] According to the fifth aspect of the present invention, the luminance of the combined pixel forming unit group in the dark display period is an average value of the luminances of the plurality of pixel forming units included in the combined pixel forming unit group. For this reason, the effect on the display image is small, and motion blur is effectively suppressed while suppressing image quality deterioration as in the third aspect.

[0023] According to the sixth aspect of the present invention, when calculating the gray level of the combined pixel forming unit group in the dark display period, the gray level of each pixel forming unit included in the combined pixel forming unit group is calculated. An average value of the determined luminance is calculated, and a gradation is calculated based on the average value. For this reason, even though the gradation and brightness are in a non-linear relationship, the gradation for generating the video signal is calculated so that the brightness of the display image does not cause a sense of incongruity in human vision. Is done.

[0024] According to the seventh aspect of the present invention, a predetermined correction is performed when calculating the gradation of the combined pixel formation unit group in the dark display period. For this reason, even if the polarity of the video signal is reversed when each scanning signal line is driven continuously, insufficient charging is suppressed.

[0025] According to the eighth aspect of the present invention, a plurality of scanning signal lines are driven simultaneously during the dark display period. Further, the luminance of the combined pixel forming unit group in the dark display period is set to a predetermined luminance of the pixel forming unit among the plurality of pixel forming units included in the combined pixel forming unit group. For this reason, the effect on the display image is small. This effectively suppresses motion blur while suppressing image quality degradation.

[0026] According to the ninth aspect of the present invention, in displaying an image for one screen, a display with a relatively high luminance is performed after a display with a relatively low luminance is performed. For this reason, the frame period When the display is switched, the change in the potential of the video signal to be supplied to each video signal line is small when the display period is switched to the bright display period. This effectively suppresses motion blur without causing insufficient charging.

[0027] According to the tenth aspect of the present invention, as in the first aspect, an afterimage of an object moving in human vision is not generated, and motion blur is suppressed. In addition, insufficient charging during a bright display period with a high contribution to an image visually recognized by human beings is suppressed, and a sense of discomfort in human vision caused by displayed images is suppressed.

Brief Description of Drawings

FIG. 1 is a block diagram showing a configuration of an active matrix liquid crystal display device according to an embodiment of the present invention.

FIG. 2A is a diagram showing a display state of a conventional display device in which a non-display period is not provided. B is a diagram illustrating a display state of a conventional display device in which pseudo impulse driving is employed. C is a diagram showing a display state in the embodiment.

FIG. 3 is a block diagram showing a detailed configuration of a display control circuit in the embodiment.

FIG. 4A is a diagram showing the dark display brightness and the bright display brightness when the brightness of the image based on the data signal DAT is 0%. B is a diagram showing the dark display brightness and the bright display brightness when the brightness of the image based on the data signal DAT is 25%. C is a diagram showing the dark display brightness and the bright display brightness when the brightness of the image based on the data signal DAT is 50%. D is a diagram showing the dark display brightness and the bright display brightness when the brightness of the image based on the data signal DAT is 75%. E is a diagram showing the dark display brightness and the bright display brightness when the brightness of the image based on the data signal DAT is 100%.

FIG. 5 is a block diagram illustrating a detailed configuration of a dark display period gradation calculation unit in the embodiment.

FIG. 6 is a flowchart showing a procedure for calculating a gradation for generating a video signal in a dark display period in the embodiment.

FIG. 7 is a signal waveform diagram in the embodiment.

FIG. 8 is a graph showing the relationship between gradation and luminance.

FIG. 9 is a signal waveform diagram in the first modified example of the embodiment. FIG. 10 is a block diagram showing a detailed configuration of a dark display period gradation calculation unit in a second modification of the embodiment.

FIG. 11A is a diagram showing one display period. B is a diagram showing a display state of an image when the two dark display periods and the one bright display period have the same length. C is a diagram showing a display state of an image when a configuration in which two scanning signal lines are simultaneously driven in the dark display period is shown.

[12] A is a diagram showing one display period. B is a diagram showing a display state of an image when the periods of the 1 dark display period and the 2 bright display period are equal in length. C is a diagram showing a display state of an image when a configuration in which two scanning signal lines are simultaneously driven in the dark display period is shown.

[13] A is a diagram showing one display period. B is a diagram showing a display state of an image in a configuration in which two scanning signal lines are simultaneously driven in the dark display period. FIG. C is a diagram showing a display state of an image when a configuration in which three scanning signal lines are simultaneously driven in the dark display period is shown.

FIG. 14 is a signal waveform diagram in a conventional example.

FIG. 15 is a diagram for explaining a luminance change in a conventional example.

Explanation of symbols

22 '' · Frame frequency converter

23 · 'Gradation generator

24 · '-喑 Tone calculation unit for display period

25 · 'Gradation selector

26 '-Bright display LUT

27 'LUT for display

60 · '' · Gamma converter

61 · '··· Average value calculator

62 · '-Tone calculator

63 · '' · Inverse gamma converter

64 '' · Line memory 200 ... Display control circuit

300 ··· Source sauce

400 ... Gate driver

500 ... Display section

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

<1. Overall configuration and operation of liquid crystal display>

FIG. 1 is a block diagram showing the overall configuration of an active matrix liquid crystal display device according to the first embodiment of the present invention. The liquid crystal display device includes a display control circuit 200, a source driver (video signal line driving circuit) 300, a gate driver (scanning signal line driving circuit) 400, and a display unit 500. The display unit 500 includes a plurality (n) of video signal lines SL1 to SLn (hereinafter also referred to as “first to nth video signal lines”) and a plurality (m) of scanning signals. Lines GLl to GLm (hereinafter also referred to as “first to m-th scanning signal lines”) and the plurality of video signal lines SL 1 to SLn and the plurality of scanning signal lines GL 1 to GLm. A plurality of (n × m) pixel forming portions provided corresponding to the intersections are included. Each pixel forming unit includes a TFT 10 which is a switching element having a gate terminal connected to a scanning signal line passing through a corresponding intersection and a source terminal connected to a video signal line passing through the intersection, and a drain of the TFT 10 It consists of a pixel electrode connected to the terminal and a liquid crystal layer provided in common to the plurality of pixel forming portions and sandwiched between the pixel electrode and the common electrode Ec. A pixel capacitor Cp is constituted by a capacitor formed by the pixel electrode and the common electrode Ec. Each pixel forming unit corresponds to one pixel in the display image, and gradation and brightness are determined for each pixel. In the following, the gradation determined for each pixel is also referred to as “the gradation of the pixel formation portion”, and the luminance determined for each pixel is also referred to as “the luminance of the pixel formation portion”. .

[0031] Display control circuit 200 receives data signal DAT and timing control signal TS sent from the outside, and receives digital video signal DV and a source start pulse signal for controlling the timing for displaying an image on display unit 500. Outputs SSP, source clock signal SCK, latch stove signal LS, gate start pulse signal GSP, and gate clock signal GCK To do. A scanning signal line driving timing signal is constituted by the gate start pulse signal GSP and the gate clock signal GCK.

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 display control circuit 200, and forms each pixel in the display unit 500. A driving video signal is applied to each of the video signal lines SL1 to SLn in order to charge the pixel capacity of the unit. At this time, the source driver 300 sequentially holds the digital video signal DV indicating the voltage to be applied to each of the video signal lines SL1 to SLn 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 at the timing when the pulse of the latch strobe signal LS is generated, and all the video signal lines SL1 to SLn are simultaneously recorded as drive video signals. The That is, in the present embodiment, the line sequential driving method is adopted as the driving method of the video signal lines SL1 to SLn. Regarding the source start pulse signal SSP and the source clock signal SCK, the period corresponding to one third of the first half of each frame period is within the period corresponding to one third of the conventional horizontal scanning period. A pulse is generated so that the voltage to be applied to all of the video signal lines SLl to SLn is applied to each of the video signal lines SL1 to SLn. Pulses are generated so that the voltages to be applied to all the video signal lines SL1 to SLn are given within a period corresponding to two-thirds of the period.

The gate driver 400 applies an active scanning signal to each of the scanning signal lines GLl to GLm based on the gate start pulse signal GSP and the gate clock signal GCK output from the display control circuit 200. Although detailed description will be given later, in the present embodiment, the gate start pulse signal GSP is generated twice over an interval corresponding to one third of the conventional one horizontal scanning period. After the first of the two pulses is generated, the gate start pulse signal GSP pulse is generated again after a period corresponding to two-thirds of one frame period. As for the gate clock signal GCK, pulses are generated at intervals corresponding to one third of the conventional horizontal scanning period in the period corresponding to one third of the first half of each frame period. In the period corresponding to two-thirds of the second half of each frame period, an interval of a period corresponding to two-thirds of the conventional one horizontal scanning period is set! / ヽ Nors is generated. Based on the gate start pulse signal GSP and the gate clock signal GCK as described above, the scanning signal is supplied to the scanning signal lines GL1 to GLm, so that one frame period is divided into two subframe periods. Has been. Conventionally, when one frame period is divided into two subframe periods as in the above-described pseudo-innox driving, image display is not performed in one of the subframe periods (a black image is inserted). The non-display period was set as the non-display period, and the other was set as the display period during which the image display was performed. In contrast, in the present embodiment, one frame period is a period during which a relatively dark image is displayed (hereinafter referred to as “dark display period”) and a period during which a relatively bright image is displayed (hereinafter referred to as “dark display period”). And “bright display period”). Specifically, the period corresponding to 1/3 of the first half of each frame period is the dark display period, and the period corresponding to 2/3 of the second half is the bright display period. Further, due to the generation of the gate start pulse signal GSP as described above, an active scanning signal is applied to each of the two scanning signal lines during the dark display period. The application of an active scanning signal to the scanning signal line is also referred to as “the scanning signal line is driven”.

As described above, the driving video signal is applied to the video signal lines SL1 to SLn, and the scanning signal is applied to the scanning signal lines GL1 to GLm, whereby an image is displayed on the display unit 500. Indicated.

Here, referring to FIG. 2, the difference between the image display state during one frame period in the present embodiment and the image display state during one frame period in the conventional display device will be described. explain. FIG. 2 is a diagram for explaining the display state of an image in one frame period (If). Figure 2 (A) shows the display state of a conventional display device that does not have a non-display period. In this display device, an image is always displayed during one frame period. Fig. 2 (B) shows the display state of a conventional display device that employs pseudo impulse drive. In this display device, image display is performed during the first half frame period of one frame period, and image display is not performed during the second half frame period. FIG. 2C shows a display state in the present embodiment. In this embodiment, a relatively dark image is displayed in the first third frame period of one frame period, and a relatively bright image is displayed in the second two third frame period of one frame period. But Is displayed.

[0036] <2. Configuration and operation of display control circuit>

FIG. 3 is a configuration diagram of the display control circuit 200 in the present embodiment. The display control circuit 200 includes a timing control unit 21, a frame frequency conversion unit 22, a gradation generation unit 23, a dark display period gradation calculation unit (dark display period gradation calculation circuit) 24, A tone selection unit 25, a bright display LUT 26, and a dark display LUT 27 are provided. The LUT is a look-up table (Look Up Table) that is referenced when data conversion processing is performed, and associates the data before conversion with the data after conversion.

[0037] The timing control unit 21 receives the timing control signal TS sent from the outside, and controls the first control signal CTL1 for controlling the operation of the frame frequency conversion unit 22 and the operation of the gradation generation unit 23. A second control signal CTL2 for controlling, a third control signal CTL3 for controlling the operation of the gradation calculation section 24 for the dark display period, and a second control signal for controlling the operation of the gradation selection section 25. 4 control signal CTL4, source start pulse signal SSP, source clock signal SCK, latch strobe signal LS, gate start pulse signal GSP, and gate clock signal GCK for controlling the timing of displaying an image on display 500 Is output.

[0038] Based on the data signal DAT sent from the outside and the first control signal CTL1 outputted from the timing control unit 21, the frame frequency conversion unit 22 increases the frequency of the data signal DAT by 1.5 times. Outputs the data signal Pb for bright display and the data signal Pd for dark display in which the frequency of the data signal DAT is tripled.

The gradation generation unit 23 receives the bright display data signal Pb and the dark display data signal Pd output from the frame frequency conversion unit 22 and the second control signal CTL2 output from the timing control unit 21. It receives and outputs a bright display gradation signal Sb and a dark display gradation signal Sd. More specifically, the gradation generation unit 23 displays the bright display while referring to the bright display LUT 26 in which the gradation of the image based on the data signal DAT is associated with the gradation of the image to be displayed in the bright display period. The data signal Pb is converted into a signal indicating the gradation of the image to be displayed in the bright display period, and the converted signal is output as the bright display gradation signal Sb. In addition, the gradation generation unit 23 refers to the dark display LUT 27 in which the gradation of the image based on the data signal DAT is associated with the gradation of the image to be displayed in the dark display period. Signal Pd is dark The signal is converted into a signal indicating the gradation of an image to be displayed in between, and the converted signal is output as a dark display gradation signal Sd. These conversions are performed based on the second control signal CTL2 output from the timing control unit 21.

[0040] In the present embodiment, the bright display LUT 26 and the dark display LUT 27 described above are equivalent to one screen of luminance based on the data signal DAT in one frame period consisting of one bright display period and one dark display period. Created to display images. This will be described with reference to FIG. Figure 4 shows the brightness of the image to be displayed during the dark display period (hereinafter referred to as “dark display brightness”) and the display period for the brightness of the image based on the data signal DAT input from the external camera. It is a figure for demonstrating conversion to the brightness | luminance (henceforth "bright display brightness | luminance") of the image which should be. In Fig. 4, the left column shows the brightness of the image based on the data signal DAT, and the right column shows the haze display brightness and the bright display brightness. Figures 4 (A), (B), (C), (D), and (E) show that the image brightness based on the data signal DAT is 0%, 25%, 50%, 75%, 100%, respectively. Shows the case. Note that the minimum luminance of the image displayed on the display unit 500 is 0%, and the maximum luminance is 100%.

First, calculation of bright display luminance will be described. When the image brightness Bdat based on the data signal DAT is 50% or less, the bright display brightness Bb is calculated by the following equation (1).

Bb = Bdat X 2 (1)

As a result, as shown in FIGS. 4A, 4B, and 4C, the luminance of the image based on the data signal DAT is converted to the bright display luminance.

On the other hand, when the luminance Bdat of the image based on the data signal DAT is larger than 50%, the bright display luminance Bb is set to 100 (%). As a result, as shown in 04 (D) and (E), the luminance of the image based on the data signal DAT is converted to the bright display luminance.

Next, calculation of dark display luminance will be described. When the image brightness Bdat based on the data signal DAT is 50% or less, the dark display brightness Bd is 0 (%). As a result, as shown in FIGS. 4A, 4B, and 4C, the luminance of the image based on the data signal DAT is converted to the dark display luminance.

On the other hand, when the image brightness Bdat based on the data signal DAT is greater than 50%, the dark display brightness Bd is calculated by the following equation (2). Bd = Bdat X 2—100 (2)

As a result, as shown in FIGS. 4D and 4E, the luminance of the image based on the data signal DAT is converted to the dark display luminance.

As described above, the bright display LUT 26 and the dark display LUT 27 are created so that the luminance based on the data signal DAT is converted into the bright display luminance and the dark display luminance. Then, by converting the signal indicating the gradation of the image based on the LUT 26 for bright display and the LUT 27 for dark display, the bright display luminance is obtained during the bright display period, and the dark display luminance is obtained during the dark display period. Each appears on the display 500. Note that Fig. 4 and numerical examples are typical and symbolic examples for explaining the display principle. Depending on actual demands such as smoothing the gradation display, it is sufficient for both 0% and 100%. It is acceptable to express darkness, brightness, brightness, and brightness, and even so, the effect of the present invention is not impaired. For example, when displaying a brightness of 50%, the bright display brightness is 90% and the dark display brightness is 10%.

The dark display period gradation calculation unit 24 receives the dark display gradation signal Sd output from the gradation generation unit 23 and the third control signal CTL3 output from the timing control unit 21. Outputs the dark display average gradation signal Sda indicating the gradation defined in common for the plurality of pixel forming portions arranged corresponding to the intersection of the two scanning signal lines and the video signal lines adjacent to each other. The The detailed configuration and operation of the dark display period gradation calculation unit 24 will be described later.

[0047] The gradation selection unit 25 is connected to the bright display gradation signal Sb output from the gradation generation unit 23, the dark display average gradation signal Sda output from the dark display period gradation calculation unit 24, and the timing. The fourth control signal CTL4 output from the control unit 21 is received, and a digital video signal DV indicating the gradation of the voltage to be applied to each video signal line SLl to SLn is output. More specifically, the gradation selection unit 25 selects either the bright display gradation signal Sb or the dark display average gradation signal Sda based on the fourth control signal CTL4, and digitally selects the selected signal. Output as video signal DV. Note that the timing at which the bright display period and the dark display period are switched by the fourth control signal CTL4 is shown. As a result, the gradation selection unit 25 selects the bright display gradation signal Sb during the bright display period, and dark display signals during the dark display period. The average gradation signal Sda is selected.

[0048] <3. Generation of video signal during dark display period>

As described above, in the present embodiment, one frame period is divided into a dark display period and a bright display period. The dark display gradation signal Sd indicating the gradation of the image to be displayed during the dark display period is converted into the dark display average gradation signal S da by the dark display period gradation calculation unit 24 as described above. The conversion will be described in detail with reference to FIG.

FIG. 5 is a block diagram showing a detailed configuration of the dark display period gradation calculation unit 24 in the present embodiment. The dark display period gradation calculation unit 24 includes an inverse gamma conversion unit 63, a line memory 64, and a gamma conversion unit 60. The gamma conversion unit 60 includes an average value calculation unit 61 and a gradation calculation unit 62.

The dark display period gradation calculation unit 24 receives the dark display gradation signal Sd and the third control signal C TL3. The inverse gamma conversion unit 63 performs inverse gamma conversion on the dark display gradation signal Sd based on the third control signal CTL3. Thus, the luminance value (hereinafter referred to as “luminance value”) L1 corresponding to the gradation indicated by the dark display gradation signal Sd is output from the inverse gamma conversion section 63. The inverse gamma conversion may be performed based on a predetermined conversion formula, or may be performed based on a pre-stored LUT!

The luminance value L1 output from the inverse gamma conversion unit 63 is provided to the average value calculation unit 61 in the gamma conversion unit 60 and also to the line memory 64. The line memory 64 can hold the luminance value L1 of the pixel formation portion for one scanning signal line. Also, the luminance value L1 held in the line memory 64 is taken out by the average value calculation unit 61 in a first-in first-out manner. Therefore, the luminance value L1 sequentially output from the inverse gamma conversion unit 63 is extracted from the line memory 64 by the average value calculation unit 61 with a delay of one horizontal scanning period. Therefore, the average value calculation unit 61 includes the luminance value L1 output from the inverse gamma conversion unit 63 and the luminance value output from the inverse gamma conversion unit 63 and extracted from the line memory 64 (hereinafter referred to as `` This is called “delayed luminance value.”) L2 is input.

The average value calculation unit 61 receives the luminance value L1 and the delayed luminance value L2, and based on the third control signal CT L3, average value thereof (hereinafter referred to as “average luminance value”) Lave. Output. The tone calculation unit 62 receives the average luminance value Lave output from the average value calculation unit 61 and receives the third luminance value Lave. The average luminance value Lave is subjected to gamma conversion based on the control signal CTL3. Thereby, the gradation corresponding to the average luminance value Lave is calculated. Then, a signal indicating the gradation is output from the gradation calculation unit 62 as the dark display average gradation signal Sda. Note that this gamma conversion may be performed based on a predetermined conversion formula as in the case of the inverse gamma conversion described above, or may be performed based on a previously stored LUT!

Next, the operation of the dark display period gradation calculation unit 24 will be described in more detail with reference to FIG. FIG. 6 is a flowchart showing a procedure for calculating a gradation for generating a video signal in the dark display period in the present embodiment. In this description, of the two scanning signal lines that are simultaneously driven during the dark display period, the scanning signal line that is driven first in each display period is referred to as a preceding line, and the other is referred to as a subsequent line. Further, a description will be given of generation of a video signal to be supplied to the video signal line by paying attention to a certain video signal line. The video signal line is called a target video signal line. In addition, the two pixel formation portions provided corresponding to the intersections of the two scanning signal lines and the video signal lines that are simultaneously driven during the dark display period are referred to as a combined pixel formation portion group.ぅ.

First, the gradation (hereinafter referred to as “preceding line gradation”) of the pixel forming portion provided corresponding to the intersection between the target video signal line and the preceding line is acquired (step S 10). ). Subsequently, the inverse gamma conversion is applied to the preceding line gradation, and the luminance value of the pixel forming portion provided corresponding to the intersection of the target video signal line and the preceding line (hereinafter referred to as “preceding line luminance”). Value ", U .;) is acquired (step S20). The preceding line luminance value corresponds to the above-described delayed luminance value L2.

Next, the process proceeds to step S 30, and the gradation of the pixel formation portion provided corresponding to the intersection of the target video signal line and the subsequent line (hereinafter referred to as “subsequent line gradation”) is acquired. Is done. Subsequently, the subsequent line gradation is subjected to inverse gamma conversion, and the luminance value of the pixel forming portion provided corresponding to the intersection of the target video signal line and the subsequent line (hereinafter referred to as “subsequent line luminance value”). Is obtained (step S40). This subsequent line luminance value corresponds to the luminance value L1 described above.

Next, the process proceeds to step S 50, and the average luminance value is calculated by dividing the sum of the preceding line luminance value and the subsequent line luminance value by 2. In other words, 2 included in the combined pixel formation unit group The average luminance (average luminance value) that should appear in each pixel forming unit is calculated. Subsequently, gamma conversion is performed on the average luminance value, and the gradation of the video signal to be supplied to the target video signal line is acquired (step S60).

As described above, the gradation for generating the video signal to be supplied to the video signal lines SL1 to SLn in the dark display period is calculated. Then, a signal indicating the calculated gradation is output from the gradation calculation unit 62 as the dark display average gradation signal Sda, and the dark display average gradation signal Sda is output as the digital video signal DV. Output from 25. Further, the gradation indicated by the digital video signal DV is converted into an analog voltage by the source driver 300 and applied to the video signal lines SL1 to SLn as drive video signals. As a result, the gray level of the combined pixel formation unit group becomes the gray level indicated by the display average gray level signal Sda, and the luminance of the above average luminance value appears in the portion corresponding to the combined pixel formation unit group of the display unit 500. become.

[0058] <4. Driving method>

Next, a method for driving the display device in the present embodiment will be described. FIG. 7 is a signal waveform diagram for one frame period in this embodiment. As shown in Fig. 7, after the pulse of the gate start pulse signal GSP (hereinafter referred to as "the first pulse of the gate start pulse signal GSP") is generated, the first pulse of the gate clock signal GCK must be generated. As a result, the scanning signal supplied to the scanning signal line GL1 in the first row becomes high level. This starts the frame period. The pulse width of the gate clock signal GCK is approximately one third of the conventional horizontal scanning period, and the scanning signal supplied to the first scanning signal line GL1 is high during the period corresponding to the pulse width. Maintained at level. After the generation of the pulse of the gate clock signal GCK, during the period until the next pulse of the gate clock signal GCK, the pulse of the gate start pulse signal GSP (hereinafter referred to as “gate start pulse signal GSP 2 This is referred to as the “second pulse”). For this reason, when the next pulse of the gate clock signal GCK is generated, the scanning signal supplied to the scanning signal line GL2 in the second row becomes high level based on the first pulse of the gate start pulse signal GSP. Based on the second pulse of the gate start pulse signal GSP, the scanning signal supplied to the scanning signal line GL1 in the first row becomes high level. That is, the first scanning signal line and the second scanning signal line are driven simultaneously. Gate clock signal GCK Again, the pulse width corresponds to approximately one third of the conventional one horizontal scanning period, so during the period corresponding to the pulse width, the first scanning signal line GL1 and the second scanning signal line GL2 And the scanning signal supplied to is maintained at a high level. Next, when the pulse of the gate clock signal GCK is generated, the scanning signal supplied to the scanning signal line GL3 in the third row becomes high level based on the first pulse of the gate start pulse signal GSP, and the gate start pulse signal Based on the second pulse of GSP, the scanning signal supplied to the scanning signal line GL2 in the second row becomes the high level. That is, the second scanning signal line and the third scanning signal line are driven simultaneously. In this way, during the period until the next pulse of the gate start pulse signal GSP is generated, the two adjacent scanning signal lines are sequentially arranged in accordance with the generation of the nose of the gate clock signal GCK. Driven simultaneously. Further, focusing on each of the scanning signal lines G L1 to GLm, the scanning signal is maintained at a high level only for a period corresponding to approximately one third of one horizontal scanning period, and is repeated twice. That is, the scanning signals supplied to the scanning signal lines GLl to GLm are at a high level for a period corresponding to approximately two thirds of one horizontal scanning period.

When all the scanning signal lines GLl to GLm are driven in this way, a pulse of the gate start pulse signal GSP (hereinafter referred to as “the third pulse of the gate start pulse signal GSP”) is generated again. To do. Thereafter, when the pulse of the gate clock signal GCK is generated for the first time, the scanning signal supplied to the scanning signal line GL1 in the first row becomes high level. That is, the scanning signal line in the first row is driven. Here, after the generation of the third pulse of the gate start pulse signal GSP, the pulse width of the gate clock signal GCK corresponds to approximately two-thirds of the conventional one horizontal scanning period. Therefore, the scanning signal supplied to the scanning signal line GL1 in the first row is maintained at a high level during a period corresponding to approximately two-thirds of the conventional one horizontal scanning period. After that, when a pulse of the gate clock signal GCK is generated, the scanning signal supplied to the scanning signal line GL2 in the second row becomes high level. That is, the second scanning signal line is driven. Again, the pulse width of the gate clock signal GCK corresponds to approximately two-thirds of the conventional one horizontal scanning period. Therefore, during the period corresponding to the pulse width, the scanning signal line GL2 supplied to the second row is scanned. The signal level becomes high. Note that after the generation of the third pulse of the gate start pulse signal GSP, the scanning signal line Are driven one by one.

[0060] After all the scanning signal lines GLl to GLm have been driven in this manner, when the pulse of the gate start pulse signal GSP and the pulse of the gate clock signal GCK are generated again, the next frame period is switched.

As described above, in the present embodiment, the first and second scanning signal lines are driven simultaneously during a period corresponding to one third of the first half of each frame period, and then 2 The first and third scanning signal lines are driven simultaneously, and so on. Two scanning signal lines are driven simultaneously. Focusing on each scanning signal line, it is driven twice in a period corresponding to one-third of the conventional one horizontal scanning period within a period corresponding to two-thirds of the conventional one horizontal scanning period.

Here, a video signal supplied to the video signal lines SL 1 to SLn during a period in which a certain scanning signal line is driven twice as described above will be described. Here, with reference to FIG. 7, the description will focus on the scanning signal line GL3 in the third row and the video signal line SL2 in the second column. Of the two driving operations described above, the first driving is referred to as the “first driving”, and the second driving is referred to as the “second driving”. As shown in FIG. 7, for the scanning signal line in the third row, the first drive is performed during the period indicated by the symbol T1, and the second drive is performed during the period indicated by the symbol T2. Among the periods indicated by the symbols T1 and T2, the second drive is performed for the scanning signal line in the second row during the period indicated by the symbol T1. On the other hand, during the period indicated by the symbol T2, the first drive is performed for the fourth scanning signal line. In other words, the scanning signal line for the second row and the scanning signal line for the third row are driven simultaneously during the period indicated by the symbol T1, and the scanning signal line for the third row and the fourth row scanning are scanned during the period indicated by the symbol T2. The signal line is driven at the same time!

The dark display gradation signal Sd indicating the gradation of the image to be displayed in the dark display period is converted into the dark display average gradation signal Sda by the dark display period gradation calculation unit 24. At that time, an average luminance value is calculated based on the luminance value L1 and the delayed luminance value L2. These are described above.

[0064] Here, regarding the generation of the video signal supplied to the video signal line SL2 in the second column during the period indicated by the symbol T1, the scanning signal line GL2 in the second row and the video signal line SL2 in the second column are used. Dark display period in the pixel formation section (corresponding to one of the combined pixel formation section group) provided corresponding to the intersection The pixel value provided corresponding to the intersection of the scanning signal line GL3 in the third row and the video signal line SL2 in the second column corresponds to the delayed luminance value L2 described above. The brightness value that should appear in the dark display period in the part (corresponding to the other of the combined pixel forming part group) corresponds to the brightness value L1 described above. Therefore, during the period indicated by T1, the luminance that should appear in the pixel formation portion provided corresponding to the intersection of the scanning signal line GL2 in the second row and the video signal line SL2 in the second column is 3 rows. The average brightness of the brightness that should appear in the pixel forming portion provided corresponding to the intersection of the second scanning signal line GL3 and the second row video signal line SL2 The video signal is supplied to the video signal line SL2 in the second column so as to appear in a portion corresponding to the forming portion (a combined pixel forming portion group).

[0065] On the other hand, regarding the generation of the video signal supplied to the video signal line SL2 in the second column during the period indicated by the symbol T2, the scanning signal line GL3 in the third row and the video signal line SL2 in the second column The luminance value that should appear in the dark display period in the pixel formation portion (corresponding to one of the combined pixel formation portion groups) provided corresponding to the intersection corresponds to the above-described delayed luminance value L2, and the fourth row The luminance that should originally appear in the dark display period in the pixel formation part (corresponding to the other of the combined pixel formation part group) provided corresponding to the intersection of the scanning signal line GL4 and the video signal line SL2 in the second column The value corresponds to the luminance value L1 described above. Therefore, during the period indicated by the reference symbol T2, the luminance that should appear in the pixel formation portion provided corresponding to the intersection of the scanning signal line GL3 in the third row and the video signal line SL2 in the second column is 4 The average luminance with the luminance that should appear in the pixel forming portion provided corresponding to the intersection of the scanning signal line GL4 in the row and the video signal line SL2 in the second column is the value of these in the display unit 500. The video signal is supplied to the video signal line SL2 in the second column so as to appear in a portion corresponding to the pixel forming portion (combined pixel forming portion group).

[0066] By supplying a video signal to each of the video signal lines SL1 to SLn as described above, during the dark display period, each pixel forming unit is reduced to one third of the conventional one horizontal scanning period. The average luminance that should appear in the dark display period appears in the pixel formation portion and the pixel formation portion arranged one row above the pixel formation portion for a corresponding period. The average luminance of the luminance that should originally appear in the dark display period appears in the pixel forming portion and the pixel forming portion arranged below one row for a period corresponding to one-half. Furthermore, during the bright display period, each pixel formation portion has a period corresponding to two-thirds of the conventional one horizontal scanning period. Therefore, the luminance that should originally appear in the bright display period appears in the pixel formation portion.

[0067] <5. Effects of generating video signal based on average luminance value>

In the present embodiment, during the dark display period, a video signal based on the above-described average luminance value Lave is supplied to the video signal lines SLl to SLn. For this reason, brightness slightly different from the brightness of the image that should be displayed during the dark display period appears on the display unit 500, but the effect on the image quality of the displayed image is minimal, and the human vision is uncomfortable. It is considered that there is almost no occurrence of this. The reason for this will be described below.

[0068] When the display of a dark image and the display of a bright image are repeated as in the present embodiment, human vision focuses on a brighter image than a dark image. In addition, changes in brightness during the bright display period have a greater effect on human vision than changes in brightness during the dark display period. Furthermore, since gradation and luminance generally have a non-linear relationship as shown in Fig. 8, the change in luminance with respect to the change in gradation increases as the brightness increases. From the above, considering the degree of contribution of the dark display period image and the bright display period image to the image viewed by humans, the dark display period image is considered to be lower.

Therefore, in the present embodiment, two scanning signal lines are simultaneously driven during the dark display period, and the average luminance of the two pixel forming units included in the combined pixel forming unit group is determined. It is assumed that the luminance appears in a portion corresponding to the combined pixel formation portion group in the display portion 500. By the way, when a dark image is displayed as a whole, if a bright part is mixed in a part of the image, the bright part is conspicuous, and the human vision is uncomfortable. Therefore, it can be said that human vision has a high demand for fineness (fineness) for dark images. In the present embodiment, when a dark image is displayed as a whole, the luminance of the image to be displayed during the dark display period is often 0% as described above. Even if the average luminance appears on the display unit 500, it is considered that there is almost no effect on the displayed image. On the other hand, when a bright image as a whole is displayed, the luminance of the image to be displayed during the bright display period is often 100% as described above. In this case, the luminance of the image for one screen is determined based on the luminance of the image displayed during the dark display period. However, since the demand for the fineness of human vision for a bright image is low, 2 Even if the average luminance of the individual pixel forming portions appears on the display unit 500, it is different from human vision. There is no sense of harm. From the above, it is considered that even if the brightness that should appear in the dark display period appears on the display unit 500 regardless of the brightness of the image to be displayed, it is almost impossible to cause a sense of discomfort in human vision. It is done.

[0070] From the above, even if the video signal based on the above average luminance value Lave is supplied to each of the video signal lines SL1 to SLn during the dark display period, there is almost no influence on the displayed image, and the human vision is uncomfortable. It is thought that it rarely occurs.

[0071] <6.Effect>

As described above, according to the present embodiment, one frame period, which is a period during which an image for one screen is displayed, is displayed as a relatively bright image compared to a dark display period in which a relatively dark image is displayed. The dark display period and the bright display period are alternately repeated. For this reason, a dark image is inserted when an image for one screen is rewritten. As a result, an afterimage of an object moving in human vision is not generated, and motion blur is suppressed. During the dark display period, each scanning signal line is continuously driven twice for a period corresponding to one third of the conventional horizontal scanning period, and two scanning signal lines are simultaneously driven. Is done. For this reason, each scanning signal line is driven in the 喑 display period for a period corresponding to two-thirds of the conventional one horizontal scanning period, but the length of the dark display period is three-thirds of one frame period. A period corresponding to 1 is sufficient. As a result, a period corresponding to two-thirds of one frame period can be set as the bright display period. As a result, a sufficient time for charging the pixel capacity of each pixel formation portion is ensured in the bright display period, and image quality deterioration due to insufficient charging can be suppressed.

[0072] <Modification 1>

Next, a modification of the above embodiment will be described. FIG. 9 is a signal waveform diagram in the first modification of the above embodiment. In this modified example, unlike the above-described embodiment shown in FIG. 7, among the plurality of scanning signal lines GLl to GLm, “first line GL1 and third line GL3”, “second line GL2 and fourth line GL4”. , “3rd line GL3 and 5th line GL5”, etc. As shown in the following figure, two scanning signal lines with one scanning signal line in between are driven simultaneously. In the dark display period, each scanning signal line is driven twice, but after the first driving (first driving), a period corresponding to approximately one third of the conventional one horizontal scanning period elapses. After that, the second drive (second drive) is performed It has been broken. Here, paying attention to the scanning signal line GL3 in the third row, the first drive is performed in the period indicated by the symbol T3, and the second drive is performed in the period indicated by the symbol T4. During the period indicated by the symbol T3 and the period indicated by the symbol T4, the video signals applied to the first column video signal line SL1 are both in positive polarity and are applied to the second column video signal line SL2. Both video signals have a negative polarity. Thus, the polarity of the video signal applied to each video signal line is the same in the two periods in which each scanning signal line is driven. Thereby, even during the dark display period, each pixel forming portion is effectively charged.

[0073] <8.Modification 2>

Next, another modification of the above embodiment will be described. FIG. 10 is a block diagram showing a detailed configuration of the dark display period gradation calculation unit 24 in the second modification of the embodiment. As shown in FIG. 10, unlike the above embodiment, a charging correction unit 65 is included in the gamma conversion unit 60. The charge correction unit 65 receives the average luminance value Lave output from the average value calculation unit 61, and corrects the average luminance value Lave based on a predetermined conversion formula. Then, the charging correction unit 65 outputs the corrected average luminance value Lave as the corrected average luminance value Lave2. The gradation calculation unit 62 receives the corrected average luminance value Lave2 output from the charging correction unit 65, and performs gamma conversion on the corrected average luminance value Lave2 based on the third control signal CTL3. As a result, the gradation corresponding to the corrected average luminance value Lave2 is calculated. Then, a signal indicating the gradation is output from the gradation calculation unit 62 as the dark display average gradation signal Sda.

As shown in FIG. 7, in the above-described embodiment, the polarity of the video signal is inverted between the period in which the first drive is performed and the period in which the second drive is performed for each scanning signal line. Therefore, the pixel capacitance may not be sufficiently charged within a period corresponding to one third of the conventional one horizontal scanning period. However, according to the present modification, the average luminance value Lave for calculating the gradation is corrected based on a predetermined conversion formula. Then, the gradation is calculated based on the corrected average luminance value Lave2, which is the corrected average luminance value Lave. Therefore, a conversion formula is set so that the pixel capacitance is charged in a shorter time. As a result, a gradation voltage is applied to each of the video signal lines SLl to SLn so that the charging rate of the pixel capacitance is higher than before correction. Is done. For this reason, the occurrence of insufficient charge rate of the pixel capacity due to the above-described inversion of the polarity of the video signal is suppressed. As a result, the luminance that actually appears in the dark display period is close to the luminance that should appear in the dark display period, and deterioration of the image quality of the entire image is also suppressed.

[0075] <9.Others>

In the above embodiment, the case where one frame period is composed of one bright display period and one dark display period has been described as an example, but the present invention is not limited to this. The number of bright display periods and dark display periods included in one frame period is not limited as long as a sufficiently dark image is inserted that does not cause an afterimage in human vision when a movie is displayed. .

FIG. 11 is a diagram for explaining an image display state when one frame period includes two dark display periods and one bright display period. If the two dark display periods and the one bright display period are equal in length, each period is equivalent to one-third of one frame period as shown in FIG. 11 (B). However, if the configuration is such that two scanning signal lines are simultaneously driven in the dark display period as in the above embodiment, one dark display period may be a length corresponding to one-half of one bright display period. One frame period is as shown in Fig. 11 (C).

FIG. 12 is a diagram for explaining an image display state when one frame period is composed of one dark display period and two bright display periods. If the periods of 1 dark display period and 2 light display period are made equal, each period is equivalent to 1/3 of one frame period as shown in FIG. 12 (B). However, if the configuration is such that two scanning signal lines are simultaneously driven in the dark display period as in the above embodiment, one dark display period may be a length corresponding to one-half of one bright display period. One frame period is as shown in Fig. 12 (C).

In the above embodiment, two scanning signal lines are simultaneously driven in the dark display period. However, the present invention is limited to two scanning signal lines driven simultaneously. It is not a thing. Depending on the screen size of the display device and the size of the dots, three or more scanning signal lines may be driven simultaneously as long as the luminance is averaged and no significant deterioration in image quality occurs. For example, a normal television signal has the power of 480 vertical resolutions. When this video is displayed on a 1080p vertical resolution display device that is compatible with i-vision, it will be magnified more than twice, so the image quality will deteriorate. Even if you do not allow It is possible. In this case, if it is limited to the dark display brightness, the effect on the image quality that can be seen even if it is displayed together is considered to be small.

FIG. 13 is a diagram for explaining a display state of an image when a configuration is adopted in which three scanning signal lines are simultaneously driven in the dark display period. Note that a configuration in which one frame period is composed of one dark display period and one bright display period is shown. As shown in the above embodiment, when two scanning signal lines are simultaneously driven during the dark display period, as shown in FIG. 13B, the dark display period is the 2nd bright display period. The length is equivalent to 1 / minute. However, if the configuration is such that three scanning signal lines are simultaneously driven during the dark display period, the dark display period may have a length corresponding to one-third of the bright display period. ) As shown.

Furthermore, in the above embodiment, the luminance in the dark display period of the two pixel forming units included in the combined pixel forming unit group is the average luminance that should originally appear in the two pixel forming units. However, the present invention is not limited to this. The brightness in the dark display period of the two pixel formation parts included in the combined pixel formation part group is the preceding line of the two scanning signal lines that are driven simultaneously (the driving signal driven first in each dark display period). Line) and each video signal line may be driven so as to have the luminance of the pixel formation portion provided corresponding to the intersection. Thereby, for each pixel formation portion, the luminance that should appear originally appears during the period from the end of charging in the dark display period to the start of charging in the bright display period. For this reason, moving image blur is suppressed while suppressing deterioration of image quality more effectively. In addition, since it is not necessary to calculate the average value of the luminance values of the pixel forming portions included in the combined pixel forming portion group, a circuit therefor is unnecessary, and the display device according to the present invention can be realized with a simpler configuration. Is possible.

[0081] Further, in consideration of the influence of the luminance error in the dark display period on the display, even if the average gradation is used instead of the average luminance, the influence on the display is relatively small and the calculation is simplified. Further, instead of obtaining the average gradation, it is also possible to use the gradation that is not larger among the target gradations.

Claims

The scope of the claims

[1] A plurality of video signal lines for transmitting a video signal based on an image to be displayed, a plurality of scanning signal lines intersecting with the plurality of video signal lines, the plurality of video signal lines, and the plurality of video signals A plurality of pixel forming portions arranged in a matrix corresponding to the intersections of the scanning signal lines, a scanning signal line driving timing signal for driving the video signal and the plurality of scanning signal lines, and Display control circuit that outputs relatively low luminance during the frame period during which an image for one screen is displayed One or more dark display periods and a relatively high luminance display Divided into one or more bright display periods, and the luminance determined based on the gradation of the image for one screen in each of the one or more dark display periods and the one or more bright display periods. By displaying the above, A Viewing device in dark display period and the one or more bright display period for displaying an image of the one screen,

The display device, wherein one dark display period is set to a period shorter than one bright display period.

[2] The display control circuit outputs the scanning signal line driving timing signal so that the plurality of scanning signal lines are simultaneously driven by a predetermined number of 2 or more during the dark display period. The display device according to claim 1.

[3] The two or more predetermined number of scanning signal lines that are driven simultaneously are a plurality of scanning signal lines arranged continuously in a direction in which the plurality of video signal lines extend,

3. The display device according to claim 2, wherein each scanning signal line is continuously driven a plurality of times during the dark display period.

[4] The two or more predetermined number of scanning signal lines that are driven simultaneously are a plurality of scanning signal lines selected every other one of the plurality of scanning signal lines,

The display control circuit and the scanning signal line driving timing signal are arranged so that the polarity of the video signal applied to each video signal line is the same in all the periods in which each scanning signal line is driven a plurality of times. The display device according to claim 2, wherein the video signal is output.

[5] The display control circuit corresponds to an intersection between the two or more predetermined number of scanning signal lines and each video signal line in a period in which the two or more predetermined number of scanning signal lines are simultaneously driven. The luminance of the combined pixel forming unit group, which is a plurality of arranged pixel forming units, is determined based on the gradation of the image for the one screen for the plurality of pixel forming units included in the combined pixel forming unit group. 3. The display device according to claim 2, wherein the video signal is output so as to have an average value of luminance to be displayed during the dark display period.

[6] The display control circuit includes a dark display period gradation calculation circuit for calculating a gradation of the combined pixel formation unit group in the dark display period,

The dark display period gradation calculation circuit includes:

6. The display device according to claim 5, wherein the gradation of the combined pixel formation unit group in the dark display period is calculated based on the average value.

[7] The gradation calculation circuit for the dark display period is corrected in advance so that the charging rate of each pixel formation unit is increased when calculating the gradation of the combined pixel formation unit group in the dark display period. The display device according to claim 6, further comprising a charge correction circuit that performs the operation.

[8] The display control circuit corresponds to an intersection between the two or more predetermined number of scanning signal lines and each video signal line in a period in which the two or more predetermined number of scanning signal lines are simultaneously driven. The luminance of the combined pixel forming unit group, which is a plurality of arranged pixel forming units, is determined for one predetermined pixel forming unit among the plurality of pixel forming units included in the combined pixel forming unit group. 3. The display device according to claim 2, wherein the video signal is output so as to have a luminance to be displayed in the dark display period determined based on the gradation of the image for one screen.

9. The display device according to claim 1, wherein, in the frame period, the one or more dark display periods precede the one or more bright display periods in time.

[10] A plurality of video signal lines for transmitting a video signal based on an image to be displayed, a plurality of scanning signal lines intersecting with the plurality of video signal lines, the plurality of video signal lines, and the plurality of video signals. A display device comprising: a plurality of pixel forming portions arranged in a matrix corresponding to intersections with a plurality of scanning signal lines,

The frame period during which an image for one screen is displayed is set to one or more dark display periods in which display of relatively low luminance is performed, and each period is longer than one dark display period The display method is divided into one or more bright display periods in which display with relatively high luminance is performed.

In the display control step, in the dark display period, the scanning signal line driving timing signal is output so that the plurality of scanning signal lines are simultaneously driven by a predetermined number of two or more. The display method according to claim 10.