JP2002318569A - Display device and driving method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device and a driving method therefor capable of suppressing picture deterioration liable to be caused when a moving picture is being displayed. SOLUTION: When a difference in brightness between consecutive frames are obtained (S103) and the difference in brightness is not less than a threshold (YES at S106), a display signal provided with a black display period is generated. Here, when the brightness in the preceding frame is higher than that in the following frame (YES at S107), a display signal having the black display period set after the video display period is generated (S108), and when the brightness in the preceding frame does not exceed that in the following frame (NO at S107), a display signal having the black display period set before the video display period is generated (S109).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying an image, and more particularly to a display device capable of suppressing image deterioration that occurs when displaying a moving image, and a driving method thereof.

[0002]

2. Description of the Related Art A display device for displaying an image is of a hold type that continuously displays the same image during one frame period,
It is divided into an impulse type in which an image is instantaneously displayed in one frame period. Examples of the hold type display device include an active matrix type liquid crystal display device and an organic electroluminescent display device. On the other hand, examples of the impulse type display device include a CRT.

FIGS. 14A and 14B are diagrams showing a change in luminance of an arbitrary pixel included in a display device during one frame period. FIG. 14A is a graph showing the change in luminance in a hold type display device, and FIG. 4) is a graph showing a change in the luminance in the impulse-type display device. FIG.
As shown in (a), in the case of a hold-type display device, a constant luminance is maintained over each frame period. On the other hand, as shown in FIG. 14B, in the case of an impulse-type display device, in each frame period, the luminance rapidly decreases with the peak at the start of the frame period.

As described above, the hold-type display device and the impulse-type display device have different display characteristics. However, for displaying moving images, the impulse-type display device is compared with the hold-type display device. Is said to be excellent. Hereinafter, this point will be described.

FIGS. 15A and 15B are explanatory diagrams showing display characteristics of a hold-type display device when a white display pattern moves on a black background, and FIG. 15A shows a state in which the display pattern moves. And (b) are diagrams showing the luminance distribution of the display pattern. In FIG. 15A, the vertical axis indicates time, the horizontal axis indicates a position in the horizontal direction on the display screen, and Pn (n: natural number) indicates each pixel. W indicates a white display pattern spread by 5 pixels in the horizontal direction of the display screen.

When such a display pattern W is moved one pixel at a time at a predetermined time in the horizontal direction of the display screen, the observer will see a straight line (dashed line V) connecting the edges of the display pattern W.
The display pattern W is followed by moving the line of sight from 1 to the broken line V4). This is the display pattern W
In the edge portion, the luminance difference between the pixels is remarkable, so that the pixel becomes a target to be watched by the observer.

In FIG. 15A, broken lines V1 and V2
Indicates the movement of the observer's line of sight when following the pixel with the smallest value of n among the pixels Pn displaying the display pattern W. More specifically, the broken line V1 indicates the movement of the observer's line of sight at the end of one frame period T for the pixel, and the broken line V2 indicates the movement of the observer's line of sight at the start of the one frame period T. Is shown.

On the other hand, broken lines V3 and V4 show the movement of the observer's line of sight when following the pixel having the largest value of n among the pixels Pn on which the display pattern W is displayed. More specifically, the dashed line V3 indicates the 1 for that pixel.
The movement of the observer's line of sight at the end of the frame period T is shown, and the broken line V4 similarly shows the movement of the observer's line of sight at the start of the one frame period T.

As described above, the line of sight of the observer who observes the display pattern W moves from the broken line V1 to the broken line V4.
However, as described above with reference to FIG. 14A, the hold-type display device has a display characteristic of maintaining a constant luminance over one frame period, so that the broken lines V1 and V2 And the broken line V3 and the broken line V
In the area between 4, the image appears to be blurred. FIG. 15 shows the reason why the image blur occurs.
This will be described in more detail with reference to FIG.

[0010] In Fig. 15B, the area on the left side of the dashed line V1 and the area on the right side of the dashed line V4 are displayed in black as a background. Therefore, as shown in FIG. 15B, the luminance is 0 on the left side of the broken line V1 and on the right side of the broken line V4.

In the region between the broken line V1 and the broken line V2 and in the region between the broken line V3 and the broken line V4, a portion that emits light and a portion that does not emit light are mixed. Since the ratio of the light-emitting portion increases from the broken line V1 to the broken line V2, the luminance increases at a constant rate until the luminance reaches the luminance B of the display pattern W. On the other hand, since the proportion of the portion that does not emit light increases from the broken line V3 to the broken line V4, the luminance decreases at a constant rate. Note that the luminance B of the display pattern W is held between the broken line V2 and the broken line V3.

As described above, the regions where the luminance changes at a constant rate (between the broken lines V1 and V2 and between the broken lines V3 and V4), that is, the region where the luminance gradient occurs, are at the edge of the display pattern W. Due to the existence, the edge portion is recognized as blurred. Also, the width L of the display pattern W
Even though 0 is for 5 pixels, the observer has the width L
The width L1 larger than 0 will be recognized.

As described above, when a moving image is displayed, image deterioration is remarkable in a hold-type display device. On the other hand, as described above with reference to FIG. 14B, the luminance of the impulse-type display device decreases rapidly with the peak at the start of the frame period. The distance between the broken line V1 and the broken line V2 and the distance between the broken line V3 and the broken line V4 in FIG. As a result, the blurred area of the edge portion becomes smaller. Therefore, it is said that the impulse-type display device is superior to the hold-type display device in displaying moving images.

By the way, attempts have been made to improve the moving image display performance by making the display characteristics of the hold type display device close to the display characteristics of the impulse type display device. As one of the attempts, a technique of providing a period for performing black display in one frame period (hereinafter, referred to as a black display period) has been proposed.

FIG. 16 is a diagram showing a change in luminance at a specific pixel when a black display period is provided during one frame period. As shown in FIG. 16, one frame period includes a video display period, which is a period for displaying a video, and a black display period. By providing the black display period in this manner, it is possible to approximate the change in luminance in the impulse-type display device shown in FIG.

FIG. 17 is an explanatory diagram showing a display characteristic of a hold type display device when a black display period is provided in each frame period and a white display pattern moves on a black background. FIG. 7A is a diagram illustrating a state in which the display pattern moves, and FIG. 7B is a diagram illustrating a luminance distribution of the display pattern.

In FIG. 17A, broken lines V1 and V2
Indicates the movement of the observer's line of sight when following the pixel with the smallest value of n among the pixels Pn on which the display pattern W is displayed. More specifically, the broken line V1 indicates the movement of the observer's line of sight at the start of the black display period Tb within one frame period T for the pixel, and the broken line V2 also focuses on the start of the video display period Ta. The movement of the observer's line of sight in each case is shown. On the other hand, broken lines V3 and V4 indicate the movement of the observer's line of sight when following the pixel having the largest n value among the pixels Pn on which the display pattern W is displayed. More specifically,
A broken line V3 indicates the movement of the observer's line of sight at the start of the black display period Tb within one frame period T for the pixel, and a broken line V4 similarly indicates the movement of the observer's line of sight at the start of the video display period Ta. Is shown.

As can be seen from a comparison between FIG. 17B and FIG. 15A, when the black display period Tb is provided during each frame period, the interval between the broken lines V1 and V2 and between the broken lines V3 and V4 Can be shortened, so that a region where a luminance gradient occurs can be reduced. Therefore,
The blur area at the edge of the display pattern W can be reduced.

Although FIGS. 16 and 17 illustrate a case where the video display period precedes the black display period within one frame period, the black display period may precede the video display period.

[0020]

However, FIG.
As shown in (b), during each frame period, the black display period T
When b is provided, the luminance of the display pattern recognized by the observer is B × (100−a) / 100. Here, a indicates the ratio of the black display period Tb in one frame period T. As is clear from this equation, when the black display period Tb is provided in each frame period in the conventional display device, there is a problem that the luminance is reduced by the proportion of the black display period Tb in each frame period.

Further, conventionally, the order of the video display period and the black display period in one frame period has been fixed.
Therefore, there is a problem that the order cannot be changed to an appropriate order according to the type of video.

The present invention has been made in view of such circumstances, and a purpose of the present invention is to provide a display capable of suppressing image deterioration that occurs when a moving image is displayed and realizing a good image display. An object of the present invention is to provide an apparatus and a driving method thereof.

[0023]

In order to solve the above-mentioned problems, a display device according to the present invention comprises a display unit having a plurality of pixels for displaying an image, and a drive unit for driving the display unit. Generating a display signal indicating a video to be displayed on the display unit in each frame period based on the video signal stored in the video signal storage unit and storing the video signal stored in the video signal storage unit; A control unit that controls a driving operation of the driving unit with respect to the display unit based on the display signal, wherein the control unit displays each of the pixels in a first frame period based on a video signal input from the outside. Calculating means for calculating the luminance of the video to be displayed and the luminance of the video to be displayed in a second frame period which is a frame period subsequent to the first frame period; and Comparing means for comparing the luminance of the image displayed in one frame period with the luminance of the image displayed in the second frame period; and performing black display during the first frame period based on a result of the comparison by the comparing means. A determination unit that determines whether or not it is necessary to provide a black display period for performing, and when the determination unit determines that it is necessary to provide the black display period, the black display period and the image display are performed. Generating means for generating the display signal in the first frame period including the video display period.

According to this structure, not all pixels perform black display, but pixels determined to need to perform black display based on a change in luminance between the first frame period and the second frame period. Only black display is performed. Therefore, it is possible to suppress blurring of an image without lowering the luminance of the entire screen.

In the display device according to the present invention,
The generating means may be configured to determine an order between the video display and the black display period based on a result of the comparison. With such a configuration, according to a change in luminance between the first frame period and the second frame period,
The video display period and the black display period can be arranged in an appropriate order. Therefore, it is possible to more effectively suppress image degradation.

The present inventors have proposed that when a pixel has a lower luminance in the first frame period than in the second frame period, that is, a higher luminance,
It has been found that image degradation can be suppressed by providing a black display period in the first frame period so that the black display period and the video display period are in order. Similarly, when the luminance in the first frame period is higher than the luminance in the second frame period, that is, when the luminance is low, the first frame period is set so as to be in the order of the video display period and the black display period. It has been found that image degradation can be suppressed by providing a black display period within the image.

[0027] Therefore, in the display device according to the present invention, the generation means may be configured such that the luminance of the image displayed in the second frame period is lower than the luminance of the image displayed in the first frame period, and When the difference between the luminance of the image displayed in one frame period and the luminance of the image displayed in the second frame period is equal to or greater than a predetermined value, the image display period is set to precede the black display period. It may be configured to generate a display signal. Also,
The generating means may be configured such that the luminance of the image displayed in the second frame period is higher than the luminance of the image displayed in the first frame period, and the luminance of the image displayed in the first frame period is different from the luminance of the image displayed in the first frame period. When the difference from the luminance of the image displayed in the two frame periods is equal to or more than a predetermined value, the display signal may be generated such that the black display period precedes the video display period. .

Further, in the display device according to the invention,
The configuration may further include a setting unit for setting the predetermined value within a range of luminance that can be displayed by the display unit. Thereby, for example, the predetermined value can be set to an appropriate value according to the user's preference or the like.

Further, in the display device according to the invention,
The video signal storage unit and the control unit may each have a storage area capable of storing the video signal for one frame. With this configuration, even when comparing the luminance of the video in the first frame period with the luminance of the video in the second frame period, that is, even when comparing the video signals of two frames, the video signal storage unit Need only have a storage area for a video signal for one frame. Therefore, an inexpensive configuration can be achieved.

In the display device according to the present invention,
It may be configured to further include a setting unit for setting the length of the black display period. Thus, for example, the length of the black display period can be set according to the user's preference or the like.

Further, in the display device according to the invention,
The video signal input from the outside indicates a gradation of a video to be displayed on the display unit, and further includes a correspondence information storage unit that stores correspondence information indicating a correspondence between the gradation and the luminance, Is based on the gradation indicated by the video signal input from the outside and the correspondence information stored in the correspondence information storage unit, and the luminance of the image displayed in the first frame period and the second frame period May be configured to calculate the luminance of the image to be displayed. Thereby, efficient digital signal processing can be performed.

In the display device according to the present invention,
The control unit further includes a correction unit that corrects the display signal generated by the generation unit such that the luminance of the image displayed in the image display period is higher than the luminance of the image displayed in the first frame period. You may have it. Thus, when a moving image is displayed, it is possible to emphasize the edge of the image displayed on the display unit and suppress blurring generated at the edge portion.

In the display device according to the invention,
The video signal input from the outside indicates a gradation of a video to be displayed on the display unit, and further includes a correspondence information storage unit for storing correspondence information indicating a correspondence between the gradation and the luminance. May be configured to convert the luminance of an image displayed during the image display period into a gradation based on the association information stored in the association information storage unit. Thereby, efficient digital signal processing can be performed.

In the display device according to the invention,
The correction means, when the brightness of the video displayed in the video display period is not shown in the corresponding information, the brightness of the video displayed in the video display period, the brightness shown in the corresponding information, It may be configured to convert to a gradation corresponding to the luminance closest to the luminance of the video to be displayed in the video display period. This makes it possible to minimize the difference between the luminance of the video displayed during the video display period determined by the correction by the correction means and the luminance of the video actually displayed on the display unit.

In the display device according to the present invention,
The correction means, when the brightness of the video displayed in the video display period is not shown in the corresponding information, the brightness of the video displayed in the video display period, the brightness shown in the corresponding information, It may be configured to convert to a gradation corresponding to the highest luminance within a range that does not exceed the luminance of the image to be displayed during the image display period.
In addition, the correction unit, when the luminance of the video displayed in the video display period is not indicated in the correspondence information, indicates the luminance of the video displayed in the video display period in the correspondence information. The luminance may be converted to a gradation corresponding to the lowest luminance within a range exceeding the luminance of the image to be displayed in the image display period among the set luminances. As a result, conversion from luminance to gradation can be performed more easily.

A method of driving a display device according to the present invention is a method of driving a display device having a display section having a plurality of pixels for displaying an image, wherein the method is based on an externally input image signal. Calculating, for each of the pixels, the luminance of an image to be displayed in a first frame period and the luminance of an image to be displayed in a second frame period that is a frame period subsequent to the first frame period; Comparing the luminance of the image displayed in the first frame period with the luminance of the image displayed in the second frame period, and a video display period and a black display for displaying an image based on the comparison result. Generating a display signal indicating an image to be displayed on the display unit including a black display period for performing the operation, and generating the display signal in the first frame period by the generated display signal. There a step of driving the display unit to display an image. This makes it possible to suppress blurring of the image without lowering the luminance of the entire screen.

In the method of driving a display device according to the present invention, the step of generating the display signal may determine the order between the video display and the black display period based on the result of the comparison. Good.

In the driving method of the display device according to the present invention, the step of generating the display signal may be such that the luminance of the image displayed in the second frame period is equal to the luminance of the image displayed in the first frame period. Is smaller than a predetermined value, and the difference between the luminance of the image displayed in the first frame period and the luminance of the image displayed in the second frame period is equal to or greater than a predetermined value. The display signal may be generated so as to precede the period.

In the driving method of the display device according to the present invention, the step of generating the display signal may be such that the luminance of the image displayed in the second frame period is equal to the luminance of the image displayed in the first frame period. If the difference between the luminance of the image displayed in the first frame period and the luminance of the image displayed in the second frame period is greater than or equal to a predetermined value, the black display period is longer than the video display period. The display signal may be generated so as to precede the period.

In the method of driving a display device according to the present invention, the image signal input from the outside indicates a gradation of a picture to be displayed on the display unit, and the step of calculating includes the Based on the correspondence information indicating the correspondence with the luminance and the gradation indicated by the video signal input from the outside,
The luminance of the image displayed in the first frame period and the second
The luminance of the video displayed during the frame period may be calculated.

Further, in the driving method of the display device according to the present invention, the generation unit generates the image so that the luminance of the image displayed in the image display period is higher than the luminance of the image displayed in the first frame period. The method may further include the step of correcting the displayed display signal.

In the method of driving a display device according to the present invention, the video signal input from the outside indicates a gray level of a video displayed on the display unit, and the step of correcting the display signal includes: The luminance of an image displayed in the image display period may be converted into a gradation based on correspondence information indicating the correspondence between the gradation and the luminance.

In the method of driving a display device according to the present invention, the step of correcting the display signal may be performed when the brightness of an image displayed in the image display period is not indicated in the correspondence information. May be converted into a gradation corresponding to the luminance closest to the luminance of the image displayed in the image display period among the luminances indicated in the correspondence information.

In the method of driving a display device according to the present invention, the step of generating the display signal may include the step of: if the luminance of an image to be displayed during the image display period is not indicated in the correspondence information, And converting the luminance of the video to be displayed into a gradation corresponding to the highest luminance within a range not exceeding the luminance of the video to be displayed in the video display period among the luminances indicated in the correspondence information. Good.

Further, in the driving method of the display device according to the present invention, the step of generating the display signal includes the step of: when the brightness of an image to be displayed in the image display period is not indicated by the correspondence information, May be converted to a gradation corresponding to the lowest luminance within a range exceeding the luminance of the image displayed during the video display period among the luminances indicated in the correspondence information. .

[0046]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a functional block diagram showing a configuration of a display device according to Embodiment 1 of the present invention. As shown in FIG. 1, the display device 1 includes a control unit 10 that generates a display signal based on a video signal as described later.
A display unit 12 for displaying an image, a drive unit 11 for controlling the drive of the display unit 12 based on a display signal generated by the control unit 10, and a storage unit 17 for storing a video signal. I have.

The display device 1 includes a video signal input terminal 13 for receiving an input of a video signal 15 from an external device, for example, a personal computer, and a threshold information 16.
And a black display period information input terminal 18 for receiving an input of black display period information 19 to be described later. Here, the threshold information 16 is data indicating a threshold for determining whether or not to provide a black display period, as described later. The black display period information 19 is data indicating the length of the black display period provided during one frame period, as described later.

The video signal input through the video signal input terminal 13 described above is temporarily stored in the storage unit 17 and then supplied to the control unit 10. The threshold information 16 and the black display period information 19 input via the threshold information input terminal 14 and the black display period information input terminal 18 are provided to the control unit 10 as they are. Then, the control unit 10 controls the video signal 15, the threshold information 16 and the black display period information 19.
Is used to execute the processing described later.

The display section 12 includes an image display section 121 for displaying an image, and a light emitting section 122 for emitting light to the image display section 121. The light emitting section 122 emits light so as to maintain a constant luminance in one frame period. Therefore, the display device 1 is classified into a so-called hold type. Therefore, if it is a hold type,
This embodiment can be applied to various display devices such as an active matrix liquid crystal display device and an organic electroluminescent display device. Hereinafter, an active matrix type liquid crystal display device will be described as an example.

FIG. 2 is a block diagram showing a configuration of a display device according to the present embodiment in the case of using an active matrix type liquid crystal display device as an example. The liquid crystal panel 121a and the backlight 122a in FIG. 2 correspond to the video display unit 121 and the light emitting unit 122 in FIG. 1, respectively. The gate driver 11a and the source driver 11b in FIG. 2 correspond to the driving unit 11 in FIG. 1, the control circuit 10a in FIG. 2 corresponds to the control unit 10 in FIG. 1, and the frame memory 17a in FIG. Each corresponds.

The above-described liquid crystal panel 121a is a well-known T
It is an FT (Thin Film Transistor) type liquid crystal display element. Therefore, the liquid crystal panel 121a has a TFT substrate (not shown) in which gate lines and source lines are arranged in a matrix, and a pixel electrode and a switching element are formed for each pixel partitioned by the gate lines and source lines. Zu). Then, the gate line and the source line of the liquid crystal panel 121a are driven by the gate driver 11a and the source driver 11b, respectively.
1a and the source driver 11b are configured to be controlled by the control circuit 10a.

The frame memory 17a is a memory for temporarily storing the video signal 15 inputted through the video signal input terminal 13, and has a storage area for storing at least one frame of the video signal 15. Have.

The control circuit 10a, like the frame memory 17a, controls the video signal 1 for at least one frame.
5 has a storage unit (not shown) capable of storing the same.

In this embodiment, the threshold information 16 and the black display period information 19 are configured to be externally input through the threshold information input terminal 14 and the black display period information input terminal 18, respectively. , Not limited to such a configuration,
For example, the configuration may be such that the control circuit 10a stores threshold information 16 and black display period information 19 given in advance.

In the display device 1 configured as described above,
The liquid crystal panel 12 is illuminated using the light emitted from the backlight 122a.
1a, the control circuit 10a controls the gate driver 11a and the source driver 11b according to the display signal generated based on the video signal 15, the threshold information 16 and the black display period information 19 as described later. Output control signals. As a result, the gate driver 11a
Applies a gate signal voltage to the gate line to sequentially turn on the switching elements of each pixel, while the source driver 11
b sequentially applies the display signal voltage to the pixel electrode of each pixel through the source line at the timing. Thereby, the liquid crystal molecules of the liquid crystal panel 121a are modulated, and the transmittance of light emitted from the backlight 122a changes. As a result, the observer who observes the display device 1
An image corresponding to the display signal is perceived.

By the way, since the human eye can perceive a luminance change at an equal ratio, a display device for displaying an image displays the relationship between the gradation and the luminance as shown in FIG. Generally, it is set to be a gamma curve). In FIG. 3, the horizontal axis represents gradation and the vertical axis represents luminance. In this figure, the gradation is 25
5 shows an example where the luminance becomes 500 cd / m ² . As described above, the display characteristic is such that the change in luminance is small when the value of the gradation is relatively small, and the change in luminance is large when the value of the gradation is relatively large. It is possible to display a proper image.

The CRT automatically displays the relationship between gradation and luminance according to the above-described gamma curve because of its display characteristics, so that a natural image for humans can be displayed without performing special signal processing. can do. On the other hand, in the case of a display device having no display characteristics such as a CRT, some correction processing is performed on the video signal so that the relationship between gradation and luminance follows the above-described gamma curve. Then, a display signal is generated. The display device 1 according to the present embodiment also performs such a correction process so that a video that is natural for humans can be displayed. Since this correction processing is generally performed by digital signal processing, a case where a digital signal is handled is also described in this specification. Therefore, description will be made assuming that the above-described video signal 15 is a digital signal. It is assumed that the value of this digital signal indicates “gradation”. It should be noted that although there is a part in this specification that describes processing based on luminance, the actual processing is naturally performed using digital signals.

Next, the operation of the display device according to the present embodiment will be described.

In this specification, the luminance at which the effect of at least reducing the afterimage is recognized is defined as the luminance of the black display. The inventors perform a subjective evaluation in order to specify the luminance at which such an effect is recognized. As a result of the subjective evaluation, when an image having a luminance of 10% or less of the luminance of the image displayed by the pixel is inserted within one frame period, a residual image can be reduced in the pixel. Do you get it. Therefore, for example, when the luminance of a certain pixel is 500 cd / m ² , the luminance of black display may be set to 50 cd / m ² or less.

FIG. 4 is a flowchart showing an operation procedure of the display device according to the present embodiment in connection with the display signal generation processing. The following processing is executed for each pixel.

When receiving an input of a video signal from an external device, the display device 1 stores the received video signal in the frame memory 17a (S101). Then, the control circuit 10a simultaneously reads out two frames of video signals at a clock frequency equal to or higher than the synchronous clock frequency of the video signals (S102).

It should be noted that the frame memory 17a has only a storage area for storing one frame of video signal,
If a video signal for a frame cannot be stored, the following processing may be performed. The control circuit 10a reads out video signals for several pixels from the frame memory 17a in advance, and stores them in the storage unit of the control circuit 10a as described above. Here, the video signal stored in the storage unit is a video signal one frame before. Next, the video signal 15 is input to the control circuit 10a in real time, and the video signal 15 is stored in an empty area of the frame memory 17a generated when the video signal of several pixels is read out as described above. I do. At the same timing, the control circuit 10a also reads out the video signal stored in the storage unit. By performing such an operation, even when the frame memory 17a has only a storage area for storing the video signal for one frame, the control circuit 10a stores the video signal for two frames as described later. A comparison process can be performed.

The write and read timings of the frame memory 17a will be described later in detail.

Next, the control circuit 10a determines in step S10
The gradations indicated by the video signals for the two frames read out in step 2 are converted into luminances using a gradation-luminance correspondence table as shown in FIG. 5 (S103). This correspondence table corresponds to the control circuit 10
It is stored in the non-volatile storage means of a. In addition,
Thus instead of using the correspondence table may be obtained brightness using the equation B = D ^G. Here, B represents luminance and D represents gradation. G is 1.5
The value is within the range from to 3.5, but it is generally considered desirable to set the value to around 2.8.

Next, the control circuit 10a determines in step S10
The luminance difference between frames is calculated using the luminance obtained in step 3 (S104). Then, a threshold indicated by the threshold information 16 input via the threshold information input terminal 14 is referred to (S1).
05), it is determined whether the luminance difference calculated in step S104 is equal to or larger than the threshold (S106). Here, if the luminance difference is not equal to or larger than the threshold (NO in S106),
A display signal indicating that the luminance corresponding to the gradation indicated by the video signal 15 is maintained over one frame period, that is, a display signal for only the video signal display period is generated (S11).
0). In this case, no black display period is provided within one frame period. As described above, when the luminance difference is smaller than the threshold, the black display period is not provided.
This is because, when the luminance difference is relatively small, the portion does not become an edge, so that when a moving image is displayed, the observer does not follow the line of sight to the portion. In order for the observer to follow the line of sight, for example, some kind of gazing target such as a contour portion of a pattern is required. for that reason,
When such a gaze target does not exist, the observer does not perceive a blurred image, and thus it is not necessary to provide a black display period.

It should be noted that this threshold is set to the threshold information input terminal 14.
Can be updated by inputting new threshold information via. Thus, the brightness can be adjusted within the range of the luminance that can be displayed by the liquid crystal panel 121a according to the characteristics of the liquid crystal panel 121a or the preference of the observer. Here, when the threshold value is set relatively small, it is determined that a black display period needs to be provided even with a slight difference in luminance, so that blurring in displaying a moving image is more effectively eliminated. There is. On the other hand, when the threshold value is set relatively large, it is not determined that the black display period needs to be provided unless there is a certain luminance difference, so that there is an advantage that a decrease in luminance can be suppressed.

If the luminance difference is equal to or larger than the threshold value in step S106 (YES in S106), the frame n
(N: natural number) the luminance B _n of the video signal is frame n + 1
It is determined whether the luminance is higher than the luminance Bn + 1 of the video signal (S107). Here, when it is determined that the luminance _Bn is higher than the luminance _{Bn + 1} (YES in S107), a display signal in which a black display period is provided so as to be in the order of the video display period and the black display period is generated. (S108). On the other hand, the brightness B
_When it is determined that _n is not greater than the brightness B _{n + 1} (S1
(NO at 07), a display signal in which a black display period is provided so as to be in the order of the black display period and the video display period is generated (S1).
09). Here, the length of the black display period provided in one frame period is the length indicated in the black display period information 19 described above. This length is changed by the observer inputting and setting black display period information 19 according to his / her preference on the display device.

The control circuit 10a outputs a control signal to the gate driver 11a and the source driver 11b based on the display signal obtained as described above. The gate driver 11a and the source driver 11b drive the liquid crystal panel 121a according to the control signal, so that an image corresponding to the display signal is displayed on the liquid crystal panel 121a.

Next, in order to facilitate understanding of the display signal thus generated, details of the display signal will be described with reference to FIG.

FIGS. 6A and 6B are explanatory diagrams for explaining a display signal generated in the display device 1 according to the present embodiment. FIG. 6A is a conceptual diagram showing the contents of a video signal, and FIG. FIG. 3C is a conceptual diagram showing the content of a display signal provided with a black display period after a display period, FIG. 4C is a conceptual diagram showing the content of a display signal provided with a black display period before a video display period, and FIG. FIG. 3 is a conceptual diagram showing the contents of a display signal without a black display period. In FIG. 6A, 101 and 102 are:
The display signals for arbitrary pixels in arbitrary consecutive frames n and n + 1 are shown. B _n and B _{n + 1} indicate luminance (more precisely, the amplitude of the video signal 15). These luminance B _n and B _{n + 1} is
This indicates the luminance in the video display period described above.

Here, referring also to the flowchart shown in FIG. 4, in the above-mentioned step S104, B _n -B
The luminance difference is calculated by executing n + 1, and if the absolute value of the luminance difference is equal to or larger than the threshold, the process proceeds to step S107. Then, in step S107, if the above-described luminance difference is a positive value, step S1 is executed.
In step 08, a display signal as shown in FIG. 6B is generated. On the other hand, when the luminance difference is a negative value, the process proceeds to step S109, and a display signal as shown in FIG. 6C is generated. If the absolute value of the luminance difference is smaller than the threshold, the process proceeds to step S110, and a display signal as shown in FIG. 6D is generated.

6B and 6C, reference numeral 103 denotes a display signal during a black display period provided within one frame period in frame n. As shown in FIG. 6B, in the above-described step S108, a display signal in which a black display period is provided so as to be in the order of the video display period and the black display period in one frame period is generated.
On the other hand, as shown in FIG.
09, a black display period in one frame period,
A display signal in which a black display period is provided so as to be in the order of the video display period is generated.

As shown in FIG. 6D, in the above-described step S110, a display signal similar to the video signal 15 is generated without providing a black display period.

FIGS. 7A and 7B are timing charts showing an example of operation timings in the display device 1 according to the present embodiment. FIG. 7A shows the timing at which the video signal 15 is input, and FIG. (C) shows the timing of reading from the frame memory, and (d) shows the timing of displaying an image on the liquid crystal panel 121a. Here, the description is made on the assumption that the frame memory 17a has a storage area for storing video signals for two frames. To facilitate understanding, a frame memory for storing a video signal for one frame out of two frames is a first frame memory, and a frame memory for storing a video signal for the remaining one frame is a second frame memory. I will call it memory.

Although the case where a frame memory capable of simultaneously performing the write operation and the read operation is used will be described, even when a frame memory which cannot perform the write operation and the read operation at the same time is used. The same processing can be performed by preventing the timings of the write operation and the read operation from overlapping.

It should be noted that in FIG. 7, one frame period is a period composed of a vertical blanking period and a video signal period in order to accurately grasp the operation timing of the display device 1. deep. Here, the video signal period is the above-described video display period or a period including the video display period and the black display period.

In FIG. 7, from D _n (n: natural number) to D
_{n + 3} indicates a video signal for an arbitrary pixel from frame n to frame n + 3.

In FIG. 7A, reference numerals 51 to 54 indicate timings at which video signals from frame n to frame n + 1 are input. In FIG. 7B, reference numerals 55 to 58 indicate timings at which the video signals from frame n to frame n + 3 are written to the first frame memory or the second frame memory, respectively. As shown in FIGS. 7A and 7B, when a video signal is input from the outside, the video signal is alternately written to the first frame memory and the second frame memory almost simultaneously with the input timing. Do.

In FIG. 7C, reference numerals 509 to 514 denote timings at which video signals are read from the first frame memory, and reference numerals 515 to 520 denote timings at which video signals are read from the second frame memory. I have. As described above, since there is a possibility that a black display period is provided when one frame period starts or ends, at least two scans are required in one frame period. Therefore, reading from the frame memory is required at least twice per one frame period.

As shown by the timings 509 and 515 and the timings 510 and 516 in FIG. 7C, the timing of reading the video signal of frame n from the first frame memory and the timing of reading the video signal of frame n + 1
The timing of reading from the frame memory is substantially the same. Therefore, it is possible to compare the luminance of the video signal between the frame n and the frame n + 1 and calculate the luminance difference between them. Then, a display signal is generated based on the luminance difference. An image corresponding to the generated display signal is displayed at timings indicated by reference numerals 521 and 522. After this, the video signal is read from the frame memory at the same timing and the display signal is generated as described above, and then the video corresponding to the display signal is displayed on the liquid crystal panel 121a.

Next, the display characteristics of the display device according to the present embodiment will be described.

FIGS. 8A and 8B are explanatory diagrams showing display characteristics of the display device according to the present embodiment when a white display pattern moves on a black background. FIG. 8A shows how the display pattern moves. And (b) is a diagram showing a luminance distribution of the display pattern. In FIG. 8A, the vertical axis indicates time, the horizontal axis indicates a position in the horizontal direction on the display screen, and Pn (n: natural number) indicates each pixel.

Further, the broken lines V1 to V4 and the broken line V
Reference numerals 5 and V8 indicate the movement of the line of sight of the observer when the observer follows the moving display pattern W. Here, broken lines V1, V2, and V5 indicate the movement of the observer's line of sight when following the pixel with the smallest n value among the pixels Pn on which the display pattern W is displayed. More specifically, broken lines V1 and V5 show the movement of the observer's line of sight at the start of the black display period Tb within one frame period T, and broken line V2 also shows the observer's line of sight at the start of the video display period Ta. This shows the movement of the line of sight.

On the other hand, broken lines V3, V4 and V8 indicate the movement of the observer's line of sight when following the pixel having the largest value of n among the pixels Pn on which the display pattern W is displayed. More specifically, the broken line V3 indicates the movement of the observer's line of sight at the start of the black display period Tb within one frame period T, and the broken lines V4 and V8 indicate the observer's line of sight at the start of the video display period Ta. This shows the movement of the line of sight.

As shown in FIG. 8 (b), the brightness is 0 in the region to the left of the broken line V1, but increases at a constant rate in the region from the broken line V1 to the broken line V2. The brightness is the brightness B × (100−a) of the display pattern W.
/ 100. Here, a indicates the ratio of the black display period Tb in one frame period T. Further, in the region from the broken line V2 to the broken line V5, the luminance increases at the same rate, and reaches the maximum luminance B on the broken line V5. Then, the brightness B is maintained in a region between the broken lines V5 and V8.

On the other hand, in the region from the dashed line V8 to the dashed line V3, the luminance decreases at a constant rate, and the luminance again becomes B × (100−a) / 100 on the dashed line V3. Then, in the region from the broken line V3 to the broken line V4, the brightness decreases at the same rate, and the brightness becomes 0 on the broken line V4.

Here, FIG. 15 and FIG. 17 showing the display characteristics of a conventional display device will be referred to as a comparative example. The blurred area shown in FIG.
The size of the region between and the broken line V5 is the same as the blur region shown in FIG. However, the width L3 of the display pattern perceived by the observer shown in FIG.
The width is smaller than the width L1 of the similar display pattern shown in FIG. Therefore, compared to the conventional display device, the display device according to the present embodiment perceives a width closer to the width of the original display pattern W. Therefore, it can be said that image degradation can be suppressed as compared with the conventional display device.

Although the black display period Tb is provided, the brightness does not decrease as shown in FIG. Therefore, bright and favorable display can be realized.

(Embodiment 2) In Embodiment 2, a black display period is provided for the pixels in the outline portion of the display pattern, and the luminance during the video display period is corrected to reduce the region where the video is blurred. 1 is an example of a display device that can be used.

The configuration of the display device according to the present embodiment is the same as that of the first embodiment, and a description thereof will be omitted. Hereinafter, the operation of the display device according to the present embodiment will be described.

FIG. 9 is a flowchart showing an operation procedure of the display device according to the present embodiment in connection with the process of generating a display signal. The same processes as those in the first embodiment are denoted by the same step numbers as those in FIG. 4 and will not be described.

When the control circuit included in the display device according to the present embodiment determines in step S106 that the luminance difference is equal to or larger than the threshold value (YES in S106), it executes a display signal generation and correction process described later. (S201).

FIG. 10 is a flowchart showing a procedure of a display signal generation and correction process executed by the display device according to the present embodiment. In the following, the ratio of the black display period in one frame period and a%, a liquid crystal panel included in the display device to a maximum luminance that can be displayed with the B _max.

The control circuit controls the video signal of frame n.
Brightness B_nIs the luminance B of the video signal of frame n + 1_{n + 1}Than
Is also determined (S301). Where shine
Degree B _nIs luminance B_{n + 1}If it is determined to be larger than (S3
01, YES), the video display period, then the black display period
A display signal provided with a black display period as described above is generated (S
302). On the other hand, the brightness B_nIs luminance B_{n + 1}Bigger than
If it is determined that the image is displayed (NO in S301), the black display period
Tables with black display periods provided in order of image display periods
An indication signal is generated (S303).

Next, the control circuit determines whether or not the following equation 1 is satisfied (S304).

_Bn > _Bmax × (100−a) / 100 Expression 1 If it is determined that Expression 1 is satisfied (YES in S304), the luminance during the video display period is set to _Bmax . The video signal generated in step S302 or S303 is corrected (S305).

On the other hand, if it is determined in step S304 that the expression 1 is not satisfied (NO in S304), the luminance during the video display period is generated in step S302 or S303 so as to be a value calculated by the following expression 2. The corrected video signal is corrected (S306).

B _n × {100 / (100−a)} Equation 2 Referring back to FIG. 9, after the control circuit executes the display signal generation and correction processing as described above, as shown in FIG. The replacement process from the luminance to the gradation is executed using the appropriate correspondence table (S202). Here, when the gradation corresponding to the luminance during the image display period after the correction as described above is shown in the correspondence table, the luminance is replaced with the gradation. For example, when the luminance is 402.64 cd / m ² , as shown in FIG. 5, 232 is shown as the corresponding gradation, and therefore, the gradation is replaced with this gradation. In this case, the luminance during the video display period after the correction is displayed as it is.

On the other hand, when the gradation corresponding to the luminance during the video display period after the first correction is not shown in the correspondence table, one of the following three replacement processes is executed. .

In the first replacement processing, a luminance closest to the luminance during the corrected image display period is searched from among the luminances shown in the correspondence table, and a gradation corresponding to the searched luminance is obtained. replace. For example, when the luminance in the video display period after being the correction is 400.00cd / m ^2, the closest luminance luminance as shown in FIG. 5 39
Since it is 8.83 cd / m ^2, it is replaced with 231 corresponding to this gradation. In the case of the first replacement processing, it is possible to minimize the difference between the luminance during the video display period after the correction and the luminance of the video actually displayed on the display screen.

In the second replacement processing, the highest luminance within a range not exceeding the luminance during the corrected video display period among the luminances shown in the correspondence table is searched.
Replace with the gradation corresponding to the searched luminance. For example, the luminance during the image display period after the correction is 40
In the case of 0.00 cd / m ² , the highest luminance within a range not exceeding this luminance is 398.83 c as shown in FIG.
d / m ² , which corresponds to a gradation of 231 corresponding to this.
Replace with In the case of the second replacement processing, it can be obtained by a simple calculation as compared with the first replacement processing.

Further, in the third replacement processing, the lowest luminance within a range exceeding the luminance during the corrected video display period among the luminances shown in the correspondence table is searched, and the searched luminance is searched. Is replaced with the gradation corresponding to. For example,
The luminance during the image display period after the correction is 400.0
In the case of 0 cd / m ² , the lowest luminance within a range exceeding this luminance is 402.64 cd / m ² as shown in FIG.
Therefore, it is replaced with 232 corresponding to this gradation. In the case of the third replacement process, similarly to the case of the second replacement process, it can be obtained by a simple calculation as compared with the first replacement process.

The control circuit outputs a control signal to the gate driver and the source driver based on the display signal obtained as described above, as in the first embodiment. When the gate driver and the source driver drive the liquid crystal panel according to the control signal, an image corresponding to the display signal is displayed on the liquid crystal panel.

Next, in order to facilitate understanding of the display signal thus generated, details of the display signal will be described with reference to FIGS.

FIG. 11 is an explanatory diagram for explaining a display signal in which a black display period is provided after a video display period generated in the display device according to the present embodiment.
(A) is a conceptual diagram showing the content of a display signal whose luminance during a video display period has been corrected to _Bn ', and (b) is a conceptual diagram showing the content of a display signal also corrected to _Bmax . FIG. 12 is an explanatory diagram for explaining a display signal in which a black display period is provided before a video display period generated in the display device according to the present embodiment, and FIG. FIG. 7B is a conceptual diagram showing the content of a display signal whose luminance during the period has been corrected to B _n ′, and FIG. 7B is a conceptual diagram showing the content of a display signal similarly corrected to B _max . Here, B _n ′ is the luminance calculated by Equation 2 described above. Note that “a” in the figure indicates the ratio of the black display period Tb in one frame period.

In these FIGS. 11 and 12, 20
Reference numeral 1 denotes a display signal during a video display period, and reference numeral 202 denotes a display signal during a black display period. Reference numeral 203 denotes a display signal during a video display period after the correction processing, and reference numeral 204 denotes a display signal during a black display period.

Here, referring also to the flowchart shown in FIG. 10, _Bn is set to B in step S302 described above.
After it is determined that the value is larger than _{n + 1} , when the process proceeds to step S306, a display signal as shown in FIG. 11A is generated, and when the process proceeds to step S305, the display signal shown in FIG.
A display signal as shown in (b) is generated. On the other hand, if it is determined in step S302 that _Bn is equal to or less than _{Bn + 1} and the process proceeds to step S305, the process proceeds to step S305 in FIG.
A display signal as shown in FIG.
When the process proceeds to 06, a display signal as shown in FIG. 12B is generated.

As described above, when the proportion of the black display period Tb in one frame period is a%, the frame n
Luminance of the image that is actually displayed on the display screen at the luminance B _n of video to be displayed in frame n {(100-
a) It is reduced by a factor of / 100 °. However, this luminance _Bn is _equal to the maximum luminance _{Bmax that} can be displayed by the display device, ie, {
0-a) / 100} times or less, the observer corrects the luminance B _n to {100 / (100-a)} times, so that the observer can display the luminance B _n over the entire frame period. It feels the same.

Next, the display characteristics of the display device according to the present embodiment will be described.

FIGS. 13A and 13B are explanatory diagrams showing display characteristics of the display device according to the present embodiment when a white display pattern moves on a black background. FIG. 13A shows how the display pattern moves. And (b) is a diagram showing a luminance distribution of the display pattern. FIG. 13 illustrates a case where display is performed on pixels at the edge of the display pattern W by the display signal corrected in step S306 described above with reference to FIG.

The broken lines V1 to V8 indicate the movement of the observer's line of sight when the observer follows the moving display pattern W. Here, the broken lines V1 and V2 and the broken lines V5 and V6 indicate the movement of the observer's line of sight when following the pixel with the smallest value of n among the pixels Pn on which the display pattern W is displayed. More specifically, broken lines V1 and V5 show the movement of the observer's line of sight at the start of the black display period Tb within one frame period T, and broken lines V2 and V6 show the observation at the start of the video display period Ta as well. The movement of the gaze of the person is shown.

On the other hand, broken lines V3 and V4 and broken lines V7 and V8 indicate the movement of the observer's line of sight when following the pixel having the largest n value among the pixels Pn on which the display pattern W is displayed. . More specifically, the broken line V3
Represents the movement of the observer's line of sight at the start of the black display period Tb within one frame period T, and includes broken lines V4 and V8.
Indicates the movement of the observer's line of sight at the start of the video display period Ta. A broken line V7 indicates the movement of the observer's line of sight at the end of the video display period Ta within one frame period T.

As shown in FIG. 13 (b), the brightness is 0 in the area to the left of the dashed line V1, but
In the region up to, the luminance increases at a constant rate, and the luminance becomes the luminance B of the display pattern W on the broken line V2. This is because in the above-described step S306, the video display period Ta
This is because the middle luminance has been corrected by the above-described equation (2).

Then, in the region from the broken line V2 to the broken line V5, the luminance further increases, and on the broken line V5, the luminance becomes B + B ×
(A / 100). Here, a is one frame period T
Shows the ratio occupied by the black display period Tb. Hereinafter, the reason why the luminance on the broken line V5 has such a value will be described.

In FIG. 13A, focusing on the pixel P1 in the nth frame, the luminance during the video display period Ta is corrected by the above equation (2). The luminance after this correction is a luminance that is perceived as equivalent to the luminance B of the display pattern W when the observer observes only the video display period Ta. Therefore, on the broken line V2, as described above,
Becomes

On the other hand, in the n-th frame, pixels P2 to P
The luminance of the pixels up to 4 is the luminance B of the display pattern W.
This is the luminance perceived when the observer keeps observing for one frame period. Therefore, when the observation is performed only during the black display period Tb in the pixel P1 as indicated by the broken line V5, the luminance perceived by the observer is B × ΔTb / (Ta + T).
b)｝, that is, B × (a / 100).

Therefore, the brightness on the broken line V5 is B + B × (a / 10) which is the sum of the brightness B when only the video display period Ta is observed and the brightness B × (a / 100).
0).

As described above, after the luminance increases in the region from the broken line V2 to the broken line V5, the broken line V5 changes to the broken line V6.
In the region up to, the luminance decreases at a constant rate, and the luminance becomes B on the broken line V6. The luminance B is maintained between the broken line V6 and the broken line V7.

Then, in the region from the dashed line V7 to the dashed line V8, the luminance increases at a constant rate, and the luminance again becomes B + B 'on the dashed line V8. Further, in the region from the broken line V8 to the broken line V3, the brightness decreases at a constant rate, and the brightness again becomes B on the broken line V3. Then, in the region from the broken line V3 to the broken line V4, the luminance further decreases, and becomes zero on the broken line V4.

Here, FIG. 8 showing the display characteristics of the display device according to the first embodiment is also referred to as a comparative example. The luminance change at the edge portion of the display pattern is steeper in the case shown in FIG. 13B than in the case shown in FIG. 8B. Therefore, blurring of an image at the edge portion can be reduced. Further, since an area having a luminance higher than the luminance of the display pattern is formed inside the edge portion, the edge is emphasized, and the effect of further reducing the blur of the image is produced. Further, similarly to the case of Embodiment 1, since the luminance is not reduced, bright and favorable display can be realized.

[0122]

As described in detail above, according to the present invention,
Since it is determined whether or not to provide a black display period for each pixel, image deterioration can be suppressed without lowering the luminance of the entire screen.

The present invention has an excellent effect such that the image degradation can be effectively suppressed by setting the black display period and the video display period in an appropriate order.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating a configuration of a display device according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a display device according to Embodiment 1 of the present invention in a case where an active matrix type liquid crystal display device is used as an example.

FIG. 3 is a graph showing a relationship between gradation and luminance.

FIG. 4 is a flowchart showing an operation procedure of the display device according to the first embodiment of the present invention in connection with a display signal generation process.

FIG. 5 is a conceptual diagram showing an example of a correspondence table between gradation and luminance stored in the display device according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram for explaining a display signal generated in the display device according to the first embodiment of the present invention;
(A) is a conceptual diagram showing the content of a video signal, (b) is a conceptual diagram showing the content of a display signal provided with a black display period after the video display period, and (c) is a black diagram before the video display period. FIG. 3D is a conceptual diagram illustrating the content of a display signal provided with a period, and FIG. 4D is a conceptual diagram illustrating the content of a display signal provided with no black display period.

FIG. 7 is a timing chart showing an example of operation timing in the display device according to Embodiment 1 of the present invention, where (a) shows a timing at which a video signal is input;
(B) shows the timing of writing to the frame memory,
(C) shows the timing of reading from the frame memory, and (d) shows the timing of displaying an image on the liquid crystal panel.

FIGS. 8A and 8B are explanatory diagrams showing display characteristics of the display device according to the first embodiment of the present invention when a white display pattern moves on a black background, and FIG. And (b) is a diagram showing a luminance distribution of the display pattern.

FIG. 9 is a flowchart showing an operation procedure of the display device according to the second embodiment of the present invention in accordance with a display signal generation process.

FIG. 10 is a flowchart showing a procedure of a display signal generation and correction process executed by the display device according to the second embodiment of the present invention.

FIG. 11 is an explanatory diagram for explaining a display signal in which a black display period is provided after a video display period generated in the display device according to the second embodiment of the present invention, and FIG. FIG. 7B is a conceptual diagram showing the content of a display signal whose luminance during the period has been corrected to B _n ′, and FIG. 7B is a conceptual diagram showing the content of a display signal similarly corrected to B _max .

FIG. 12 is an explanatory diagram for explaining a display signal in which a black display period is provided before a video display period generated in the display device according to the second embodiment of the present invention; FIG. 7B is a conceptual diagram illustrating the content of a display signal whose luminance during a display period has been corrected to B _n ′, and FIG. 7B is a conceptual diagram illustrating the content of a display signal also corrected to B _max . Here, B _n ′ is the luminance calculated by Equation 2 described above.

13A and 13B are explanatory diagrams illustrating display characteristics of the display device according to the present embodiment when a white display pattern moves on a black background, and FIG. 13A illustrates a state in which the display pattern moves. (B) is a diagram showing the luminance distribution of the display pattern.

14A and 14B are diagrams illustrating a change in luminance in an arbitrary pixel included in the display device during one frame period, in which FIG. 14A is a graph illustrating the change in luminance in a hold-type display device, and FIG. 6 is a graph showing a change in the luminance in a display device of a type.

15A and 15B are explanatory diagrams illustrating display characteristics of a hold-type display device when a white display pattern moves on a black background, and FIG. 15A illustrates a state in which the display pattern moves; () Is a diagram showing a luminance distribution of the display pattern.

FIG. 16 is a diagram illustrating a change in luminance of a specific pixel when a black display period is provided in one frame period.

FIG. 17 is an explanatory diagram showing display characteristics of a hold type display device when a black display period is provided in each frame period and a white display pattern moves on a black background; FIG. 7A is a diagram showing a state in which the display pattern moves, and FIG. 7B is a diagram showing a luminance distribution of the display pattern.

[Explanation of symbols]

 Reference Signs List 1 display device 10 control unit 10a control circuit 11 drive unit 11a gate driver 11b source driver 12 display unit 13 video signal input terminal 14 threshold information input terminal 15 video signal 16 threshold information 17 storage unit 17a frame memory 18 black display period information input terminal 19 Black display period information 121 Image display unit 121a Liquid crystal panel 122 Light emitting unit 122a Backlight

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/20 G09G 3/20 641P 642 642D 660 660V H04N 5/66 H04N 5/66 A F term (Reference) 2H093 NA16 NA51 NC29 NC34 ND09 5C006 AA01 AA14 AC21 AF45 AF46 BB16 BC12 BF14 FA54 5C058 AA09 BA01 BA05 BA07 BA13 BA33 BB03 BB10 BB11 BB23 5C080 AA10 BB05 DD30 EE29 FF11 GG12 JJ02 JJ04 JJ04 JJ04 JJ04 JJ04 JJ04JJ05

Claims (23)

[Claims] 1. A display unit having a plurality of pixels for displaying an image, a drive unit for driving the display unit, a video signal storage unit for storing an externally input video signal, and the video signal storage A control unit that generates a display signal indicating an image to be displayed on the display unit in each frame period based on the image signal stored in the unit, and controls a driving operation of the driving unit on the display unit by the generated display signal. The control unit is configured to determine, for each pixel, a luminance of an image to be displayed in a first frame period and a second frame period which is a frame period next to the first frame period, based on an externally input image signal. Calculating means for calculating the luminance of the video image to be displayed in the first step, and displaying the luminance of the image displayed in the first frame period and the second frame period calculated by the calculating means. Comparing means for comparing the brightness of an image to be read, and determining whether or not it is necessary to provide a black display period for performing black display during the first frame period based on a result of the comparison by the comparing means. Means for generating the display signal in the first frame period including the black display period and a video display period for performing video display when the determination unit determines that the black display period needs to be provided. A display device having a generation unit. 2. The display device according to claim 1, wherein the generation unit is configured to determine an order between the video display and the black display period based on a result of the comparison. 3. The image processing apparatus according to claim 1, wherein the luminance of the video displayed in the second frame period is lower than the luminance of the video displayed in the first frame period, and the video displayed in the first frame period. And when the difference between the luminance of the image and the luminance of the image displayed in the second frame period is equal to or greater than a predetermined value, the display signal is generated such that the image display period precedes the black display period. The display device according to claim 2, wherein: 4. The image generating apparatus according to claim 1, wherein the luminance of the video displayed in the second frame period is higher than the luminance of the video displayed in the first frame period, and the video displayed in the first frame period. And when the difference between the luminance of the image to be displayed in the second frame period and the luminance of the image is equal to or greater than a predetermined value, the display signal is generated such that the black display period precedes the video display period. The display device according to claim 2, wherein: 5. The display device according to claim 3, further comprising a setting unit for setting the predetermined value within a range of luminance that can be displayed by the display unit. 6. The video signal storage unit and the control unit,
The display device according to claim 1, further comprising a storage area capable of storing the video signal for one frame. 7. The display device according to claim 1, further comprising a setting unit for setting a length of the black display period. 8. A correspondence information storage section for storing correspondence information indicating a correspondence between a gradation and a luminance, wherein the video signal inputted from the outside indicates a gradation of a picture to be displayed on the display section. The calculating means is configured to determine a luminance of an image to be displayed in the first frame period based on a gradation indicated by the image signal input from the outside and the correspondence information stored in the correspondence information storage unit. The display device according to claim 1, wherein the display device is configured to calculate a luminance of an image to be displayed in a second frame period. 9. The control unit corrects a display signal generated by the generation unit such that luminance of an image displayed in the image display period is higher than luminance of an image displayed in the first frame period. The display device according to claim 1, further comprising a correction unit that performs correction. 10. A correspondence information storage unit for storing correspondence information indicating a correspondence between a gradation and a luminance, wherein the video signal input from the outside indicates a gradation of a video displayed on the display unit. The image processing apparatus according to claim 9, wherein the correction unit is configured to convert a luminance of an image displayed in the image display period into a gradation based on the correspondence information stored in the correspondence information storage unit. The display device according to the above. 11. The image processing apparatus according to claim 1, wherein, when the brightness of the video displayed in the video display period is not indicated in the correspondence information, the correction unit determines the brightness of the video displayed in the video display period in the correspondence information. 2. The image processing apparatus according to claim 1, wherein the luminance is converted into a gradation corresponding to a luminance closest to a luminance of an image to be displayed during the image display period.
The display device according to 0. 12. The image processing apparatus according to claim 1, wherein, when the brightness of the video displayed in the video display period is not indicated in the correspondence information, the correction unit determines the brightness of the video displayed in the video display period in the correspondence information. The display device according to claim 10, wherein the display device is configured to convert into a gradation corresponding to the highest luminance within a range that does not exceed the luminance of an image to be displayed in the image display period among the existing luminances. 13. The image processing apparatus according to claim 13, wherein, when the brightness of the video displayed in the video display period is not indicated in the correspondence information, the correction unit determines the brightness of the video displayed in the video display period in the correspondence information. The display device according to claim 10, wherein the display device is configured to convert into a gradation corresponding to the lowest luminance within a range exceeding the luminance of an image to be displayed in the image display period among the existing luminances. 14. A method for driving a display device including a display unit having a plurality of pixels for displaying an image, wherein each of the pixels is controlled in a first frame period based on an externally input image signal. Calculating the luminance of the video image to be displayed and the luminance of the video image to be displayed in the second frame period that is the next frame period of the first frame period; and Comparing the luminance with the luminance of the image displayed in the second frame period; and, based on the result of the comparison, whether or not it is necessary to provide a black display period for performing black display in the first frame period. Determining whether the black display period needs to be provided, and displaying the black display period on the display unit including the video display period for performing video display. Driving a display device, comprising: generating a display signal indicating an image to be displayed; and driving the display unit to display an image in the first frame period by the generated display signal. Method. 15. The step of generating the display signal,
The method according to claim 14, wherein an order between the image display and the black display period is determined based on the comparison result. 16. The step of generating the display signal comprises:
The brightness of the image displayed in the second frame period is smaller than the brightness of the image displayed in the first frame period,
In addition, when the difference between the luminance of the image displayed in the first frame period and the luminance of the image displayed in the second frame period is equal to or greater than a predetermined value, the image display period precedes the black display period. 16. The method according to claim 15, wherein the display signal is generated as described above. 17. The step of generating the display signal,
The brightness of the video displayed in the second frame period is higher than the brightness of the video displayed in the first frame period,
In addition, when the difference between the luminance of the image displayed in the first frame period and the luminance of the image displayed in the second frame period is equal to or greater than a predetermined value, the black display period precedes the video display period. 16. The method according to claim 15, wherein the display signal is generated as described above. 18. The image signal input from the outside indicates a gradation of a picture to be displayed on the display unit, and the calculating step includes the correspondence information indicating a correspondence between a gradation and a luminance and the external information. 15. The display device according to claim 14, wherein the luminance of an image displayed in the first frame period and the luminance of an image displayed in a second frame period are calculated based on a gray scale indicated by an image signal input from the CPU. Drive method. 19. The apparatus according to claim 19, further comprising the step of correcting the display signal generated by said generating means so that the luminance of the image displayed in the image display period is higher than the luminance of the image displayed in the first frame period. A method for driving a display device according to claim 14. 20. The video signal input from the outside, which indicates a gray level of an image to be displayed on the display unit, wherein the step of correcting the display signal includes correspondence information indicating a correspondence between a gray level and a luminance. 20. The method of driving a display device according to claim 19, wherein the luminance of an image displayed in the image display period is converted into a gradation based on the image. 21. The step of correcting the display signal,
When the brightness of the video displayed in the video display period is not indicated in the correspondence information, the luminance of the video displayed in the video display period is displayed in the video display period out of the brightness indicated in the correspondence information. 21. Conversion to a gradation corresponding to the luminance closest to the luminance of the video to be reproduced.
4. The method for driving a display device according to claim 1. 22. The step of generating the display signal,
When the brightness of the video displayed in the video display period is not indicated in the correspondence information, the luminance of the video displayed in the video display period is displayed in the video display period out of the brightness indicated in the correspondence information. 21. The method of driving a display device according to claim 20, wherein the gradation is converted into a gradation corresponding to the highest luminance within a range not exceeding the luminance of the image to be reproduced. 23. The step of generating the display signal,
When the brightness of the video displayed in the video display period is not indicated in the correspondence information, the luminance of the video displayed in the video display period is displayed in the video display period out of the brightness indicated in the correspondence information. 21. The method of driving a display device according to claim 20, wherein the conversion is performed to a gradation corresponding to the lowest luminance within a range exceeding the luminance of an image to be reproduced.