JP2003284088A - Color sequential display method, display device and driving method thereof - Google Patents

Abstract

(57) [Problem] In a display device of a color sequential display method, reduction of color breakup and reduction of power consumption cannot be achieved at the same time. SOLUTION: A set of points in which color information of a video signal of one screen is plotted in a three-dimensional color stimulus space includes a predetermined percentage of plot points, and an origin in the three-dimensional color stimulus space is set to one. Find a parallelepiped at two vertices, and create a three-color image corresponding to three sides extending from the origin of this parallelepiped,
It is displayed in each of the three subfields of the color sequential display method. According to this display method, since the subfields do not display the primary colors, the effect of reducing color breakup is high, and a color image can be displayed in the minimum required three subfields, so that power consumption can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color display device. In particular, the present invention relates to a technology suitable for reducing power consumption and reducing color rainbow that occurs when a line of sight is greatly distorted and color breakage that occurs when displaying a moving image in a color display device using a color sequential display method.

[0002]

2. Description of the Related Art A red (R), green (G) or blue (B) image is displayed, and in conjunction with it, a light source corresponding to each color is illuminated from the back in an arbitrary order to perform color display. The method is called the color sequential display method. This method, which is also called a field sequential color method, has recently attracted attention as a display method that does not require a color filter and that facilitates high definition. However, as a problem peculiar to the color-sequential display method, an image in which two or more colors of R, G, and B are mixed is expressed by a combination of R, G, and B primary color subfields. When the observer's eyes follow it, there is a problem of color breakup in that the time lag of the R, G, B emission timing is perceived as a spatial lag. Also, regardless of whether it is a still image or a moving image, when the line of sight is diverted from the screen, a so-called color rainbow phenomenon occurs in which colors are recognized over the entire screen, which gives viewers an unpleasant feeling. With respect to these problems, JP-A-8
In Japanese Patent Laid-Open No. 101672, an achromatic color signal calculated from RGB signals is generated, and four of red, green, blue, and white (W) are converted into four.
A measure for preventing color breakup displayed in the subfield is disclosed (FIG. 16). Here, the subfield is one frame period which is the minimum unit required to display one image,
The individual time widths divided into R, G, B and R, G, B, W are shown. In this specification, the color break in a narrow sense that occurs when displaying a moving image and the color rainbow phenomenon are collectively referred to as color break.

[0003]

[Problems to be Solved by the Invention]
The method of Japanese Patent No. 2 has a remarkable effect on a completely achromatic portion. In this method, when the luminance ratio of the achromatic color component is set to be high, the color breakup prevention effect is also enhanced. However, if the luminance ratio of the achromatic component is increased, the amount of light actually extracted in the RGB subfields becomes small, even though the RGB backlight is on. That is, the transmittance of the liquid crystal cell becomes low. Therefore, the luminance component that is not effectively used increases. As a result, power consumption increases, environmental load increases, and it is difficult to apply to a display device driven by a built-in battery.

[0004]

As a method for solving the above problems, in the first color sequential display method of the present invention, one frame period is divided into three subfields, and each of these three subfields is divided. In a color sequential display method for displaying an image of an arbitrary color to obtain a color image, color information of an image signal for one screen is plotted at a predetermined ratio from a set of points plotted in a three-dimensional color stimulus space. A parallelepiped that contains points and has the origin at one vertex in the three-dimensional color stimulus space is obtained, and three color images corresponding to the three sides extending from the origin of this parallelepiped are displayed in three subfields, respectively. . Here, the three-dimensional color stimulus space is an RGB utilizing the fact that in a color mixture system, all color lights can be expressed by an additive color mixture of three appropriately selected original stimuli.
It is a three-dimensional coordinate system in which the three primary colors are taken on three orthogonal axes. According to the display method of the present invention, since the subfield does not display the primary color, the effect of improving color breakup is very high depending on the type of image. In the most extreme example, in a black and white image, the three subfields can be exactly the same and no color breakup occurs.

Although the setting of the parallelepiped is arbitrary, it is preferable that the volume of the parallelepiped in the three-dimensional color stimulus space is minimized for each frame period because low power consumption driving is possible. Further, if the predetermined ratio is 100%, no color change or brightness change from the input video signal occurs.

The second color sequential display method of the present invention can also be used in combination with the method disclosed in Japanese Patent Application Laid-Open No. 8-101672 as a conventional example.
That is, the achromatic component is extracted from the video signal for one screen, the image of the achromatic component is displayed in the white subfield, and the color information of the video signal excluding the achromatic component assigned to the white subfield is 3 From the set of points plotted in the three-dimensional color stimulus space, a parallelepiped that contains a predetermined proportion of plotted points and has the origin in one point in the three-dimensional color stimulus space is obtained, and the remaining three subfields are set. 3 corresponding to the three sides extending from the origin of this parallelepiped
It is to display each color image. In this method, the introduction of the white subfield consumes more power than the first method, but is preferable because the effect of preventing color breakup is high even in an image having many colors in one screen.

As in the first method, the second method is preferable because the volume in the three-dimensional color stimulus space of the parallelepiped is minimized for each frame period because low power consumption driving is possible. Further, by setting an upper limit on the luminance ratio of the achromatic color component, the effect of preventing color breakup can be controlled and the power consumption can be reduced. According to a subjective evaluation by the inventors, it has been found that even if the upper limit of the luminance ratio of the achromatic component is 70%, the deterioration of the image due to the color break is within the allowable limit.

Further, it is possible to enhance the effect of preventing color breakage by setting the above-mentioned predetermined ratio, that is, the ratio of the parallelepiped containing the plot points to less than 100%. At this time, it is preferable to substitute the plot point not included in the plot point with the plot point in the parallelepiped closest to the plot point because the color change and the brightness change are small.

Further, the predetermined ratio may be appropriately changed depending on the image to be displayed. For example, in the case of video display,
It is extremely impossible to check the details of the image, and it is considered that it is not necessary to set the predetermined ratio to 100%.

If the predetermined ratio is not 100%, priority should be given to pixels with high brightness that are easily visible to the user. Therefore, it is preferable to set a parallelepiped after performing a predetermined weighting for giving priority to a pixel having high brightness from the set of plot points. As the predetermined weighting, a method of making the plot point proportional to the x-th power of the distance from the origin in the three-dimensional color stimulation space can be considered. Here, x may be set appropriately such as a real number of 0 or more and 3 or less.

The color sequential display method described above can be applied to a method of driving a liquid crystal display device. In particular, the volume of the parallelepiped in the three-dimensional color stimulus space is minimized, and further, the three primary colors are set so that the brightness of the three primary color light sources becomes the minimum in accordance with the three-dimensional color stimulus space value of the color corresponding to the three sides of the parallelepiped. It is preferable to control the luminance of the light source and the transmittance of the pixel formed of the liquid crystal cell in synchronization with each other because the power consumption can be reduced. This is also the case when an achromatic subfield is provided. However, in that case, even in the white subfield, the brightness of the three primary color light sources is set to the minimum value in consideration of the brightness thereof.
It is preferable to control the luminance of the primary color light source and the transmittance of the pixel formed of the liquid crystal cell in synchronization.

Further, the display device of the present invention has a plurality of light sources of at least three primary colors of red, green, and blue, and a plurality of light sources having means for controlling light transmissivity independently of other pixels arranged in a matrix. Of pixels, a means for inputting a video signal, a storage means capable of storing a video signal for one screen, and a set of a predetermined proportion of a set of points where the stored video signal is plotted in the three-dimensional color stimulation space. A calculation means for obtaining a parallelepiped which includes a plot point and has an origin at one vertex in the three-dimensional color stimulus space, and the brightness of the light source in red green blue 3
A display device comprising light source control means for independently controlling each color and for making three colors corresponding to three sides extending from the origin of the parallelepiped emit light in three subfields in which one frame period is divided into three. is there. The light sources of the three primary colors of red, green, and blue are light emitting diodes, and the means for controlling the light transmittance independently of other pixels are a thin film transistor and a gate driver and source driver for controlling it, and a liquid crystal cell for a pixel, etc. Can be used.

Further, for the reason already described, it is preferable to add a minimizing means for giving the calculating means a function of minimizing the volume of the parallelepiped in the three-dimensional color stimulus space for each frame period, Further, there is provided a synchronization control means for synchronously controlling the luminance of the three primary color light sources and the pixel transmittance so that the luminance of the three primary color light sources becomes the minimum in accordance with the three-dimensional color stimulus space values of the colors corresponding to the three sides of the parallelepiped. It is preferably added.

Further, as a display device using an achromatic component as one sub-field, a front surface of a light source having a light source of at least three primary colors of red, green and blue, and a means for controlling the light transmittance independently of other pixels. A plurality of pixels arranged in a matrix, a means for inputting a video signal, a storage means for storing a video signal for one screen, an achromatic color component extracted from the stored video signal, and the achromatic color component is extracted. A parallelepiped that includes a predetermined proportion of plot points in a set of points in which the color information of the excluded video signal is plotted in the three-dimensional color stimulus space and has the origin in the three-dimensional color stimulus space at one vertex. The calculation means for obtaining the achromatic component, the achromatic component, and the three colors corresponding to the three sides extending from the origin of the parallelepiped
A display device provided with a light source control means for causing each of the divided four sub-fields to emit light is preferable.

Also in this case, for the reason described above, it is preferable to add means for giving the arithmetic means a function of minimizing the volume in the three-dimensional color stimulus space of the parallelepiped for each frame period. Further, according to the luminance of the achromatic component and the three-dimensional color stimulus space value of the color corresponding to the three sides of the parallelepiped, the luminance of the three primary color light sources and the pixel transmittance are synchronized so that the luminance of the three primary color light sources becomes the lowest. Therefore, it is preferable that a means for controlling is added.

Further, it is preferable that a means for setting an upper limit on the luminance ratio of the achromatic color component is added because the power consumption can be reduced. Furthermore, it is more preferable that the user can add a means for switching the upper limit of the luminance ratio of the achromatic color component, because the user can select the video display that is in use in consideration of color breakup and power consumption.

Further, if a switching means for switching the inclusion ratio of plot points relating to the setting of the parallelepiped by the user is added, the user arbitrarily sets the color reproducibility and the brightness reproducibility of the image to some extent according to the displayed image. It is preferable because it is possible. For example, when displaying a still image, the inclusion rate of the plot points is set to near 100%, and when displaying a moving image,
A usage method such as 90% is conceivable.

Further, it is more preferable to add a means for automatically changing the inclusion ratio of the plot points, which automatically changes the inclusion ratio of the plot points according to the display image.

When the inclusion rate of the plot points is less than 100%, the non-inclusive plot points that substitute the non-enclosed plot points with the plot points in the parallelepiped closest to the unincluded plot points. The addition of the alternative means is preferable because no remarkable color change or brightness change occurs.

Further, the liquid crystal is in a nematic phase, and OCB (optically
Compensated bend) mode liquid crystals are preferred.
In the liquid crystal display device of the color sequential method, at least about 3 times as much as usual.
Although a double response speed is required, a high-speed response is relatively easy to realize in a display utilizing bend alignment. For example,
It is preferable that the liquid crystal cell is a normally white type and that the response time from black display to white display is 5.0 ms or less.
As a result, the response of the liquid crystal is almost completed within one subfield even when so-called black insertion driving is performed.

Further, the response of the liquid crystal can be speeded up by narrowing the cell gap. However, in the OCB mode liquid crystal, the modulation factor is determined by the Δnd product, so Δnd is preferably 0.5 μm or more and 1.0 μm or less.
However, Δn is the refractive index anisotropy of the liquid crystal at room temperature at 589 nm, and d is the cell gap. According to the study by the inventors, the liquid crystal used at this time has a bulk viscosity of 60 mPa · s at room temperature from the viewpoint of high-speed response.
The following is particularly preferable. Further, if the voltage applied to the liquid crystal cell during black display is too high, the load applied to the driving circuit is large, and if it is too low, the reverse transition is likely to occur from the bend alignment to the splay alignment. Therefore, it may be 4.5 V or more and 7.5 V or less. preferable. Further, it is preferable to use a cyano-containing liquid crystal as the liquid crystal having a bulk viscosity of 60 mPa · s or less even if Δn is high. From the viewpoint of achieving both reliability and low viscosity, the cyano content is 5% or more and 20% or less. The following are particularly preferred.

In the case of a direct type liquid crystal display device in which the backlight is divided into blocks, an independent backlight (light source) is provided in each area. Therefore, the present invention can be applied to each area if the area division processing means for independently processing the video signal to each area is provided similarly to the video signal for one screen described above. The color breakage reduction effect is easily obtained, which is preferable.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) Hereinafter, a first color sequential display method of the present invention will be described in detail as a first embodiment with reference to the drawings. A specific part will be described as a driving method of the liquid crystal display device.

FIG. 1 shows a method for setting a parallelepiped in a three-dimensional color stimulus space in the color sequential display method according to the present invention and a color sequential display method for colors 1, 2, and 3 obtained thereby. Here, the three-dimensional color stimulus space is an RGB3 based on the fact that in a color mixture system, all color lights can be expressed by an additive color mixture of three appropriately selected original stimuli.
The primary colors are three orthogonal axes (B, R, G) = (1,0,0),
It is a three-dimensional coordinate system based on (0,1,0) and (0,0,1). First, the color information of all the input video signals for one screen is plotted in the three-dimensional color stimulus space by the calculating means. The set of plotted points is included in the cube of FIG. Therefore, it is possible to display any color light in the color sequential display of the RGB three primary colors. However, (B, R, G) = (1,
0,0) or (B, R, G) = (0,1,0), (B,
R, G) = (0,0,1) is not included. In this case, it is not necessary to use the three primary colors in the subfield. Further, the brightness does not have to be the highest (= 1). That is, when a parallelepiped including all plot points (shown by a broken line in FIG. 1B) is set as shown in FIG. 1B, by using color 1, color 2 and color 3 in 3 subfields, All colored light inside the parallelepiped is represented.
Therefore, it is possible to display a video signal for one screen. Here, the method of setting the parallelepiped has arbitrariness. In the case of a liquid crystal display device, an image is displayed by a backlight of three primary colors (for example, a light emitting diode) and a liquid crystal cell that controls the transmittance of the light. Therefore, the power consumption can be reduced by reducing the volume of the parallelepiped as much as possible and adjusting the luminance of the three primary color backlights to color 1, color 2 and color 3 in each subfield as shown in FIG. . At this time, the transmittance of the liquid crystal is relatively highest (= 1). Most preferably, the calculation is repeated every one frame period so that the volume of the parallelepiped is minimized, and according to the calculation result,
The synchronization control means controls the brightness of the backlight and the transmittance of the liquid crystal cell in synchronization with each other.

By the above method, the reduction of color breakage and the reduction of power consumption, which were difficult in the past, can be achieved to some extent. For example, consider an image in which an almost white object passes through an almost black background. In this case, the plot points of the color information of the video signal are (B, R,
G) = (1,1,1) and two points near the origin. Therefore, color 1, color 2 and color 3 are all (B, G,
R) = (1/3, 1/3, 1/3), and the three subfields are almost the same. In conclusion, in an image in which a white object passes through a black background, the application of the present invention does not cause color breakup. Also, the brightness of the backlight is reduced to 1/3 and the power consumption is reduced. This is always true when the image is achromatic.

Further, the effect is high even in an image in which one of RGB is hardly used. For example, consider an image in which an almost yellow (Y) object passes through an almost red background. Y is (B, R, G) = (0,1,1),
Since it does not have the B component, the plot of the color information of the video signal in the three-dimensional color stimulus space is almost a set of points on the RG plane. Therefore, a subfield whose main component is B,
That is, the color 1 in FIG. 1C is rarely used. Then, as color 2 and color 3, color 2 (B, G, R)
= (0,0,1) and color 3 (B, G, R) = (0,
1, 1) is set. Then, no color breakup occurs even in an image in which a yellow (Y) object passes through on a red background. Moreover, since the B backlight hardly emits light, power consumption is also reduced.

In the first embodiment, the case of setting a parallelepiped including all the plotted points is described. However, the present invention is not limited to this. That is, a method of setting a parallelepiped that includes a predetermined proportion of the plotted points is set. For example, in the case of a display device having about 1 million pixels, (B, G, R) =
Assume a case where (0,0, r) exists in only a few pixels. Here, r is a real number of 0 or more and 1 or less. When a parallelepiped including all points is set as in the first embodiment, one subfield is composed of only R. Therefore, it is difficult to obtain the effect of reducing color breakage.
However, even if the pure R of a few pixels is ignored, it cannot be recognized by the user. That is, the R is ignored and the effect of reducing the color breakup is obtained only by setting the predetermined ratio to about 99.999%. Points not included in the parallelepiped are replaced by points in the parallelepiped, but may be replaced by points having the shortest distance in the three-dimensional color stimulus space.

Further, it is considered that the optimum value of the predetermined ratio varies depending on the type of image, for example, still image or moving image. In the case of video display, even if you keep the prescribed ratio low,
It is considered unlikely that the user will recognize the difference.

Further, it is effective to weight the plotted points appropriately and set a parallelepiped. For example, if weighting is performed so as to be proportional to the distance from the origin, a point having high brightness and easily visible to the user is likely to be included in the parallelepiped. More specifically, the weighting may be performed in proportion to the xth power of the distance from the origin. Here, x is a real number of 0 or more and 3 or less. x = 0
Corresponds to a case where weighting is made uniform, and x = 3 corresponds to a case where a point having high luminance is evaluated with a very high weighting.

This method in which the predetermined ratio is less than 100% can be positioned as a technique for achieving both reduction of color breakup and reduction of power consumption while sacrificing color reproducibility to some extent. For example, if the predetermined ratio is set as low as about 50%, it is considered that the probability of occurrence of the primary color subfield is extremely low when the present invention is applied to the display of normal TV images. Therefore, the effect of reducing color breakage can be obtained. Further, since one frame is divided into the minimum required three subfields, there are few luminance components that are not used for emitting light, and power consumption is reduced. Therefore, when it is important to reduce power consumption such as mobile applications,
It is particularly effective and preferable to keep the predetermined ratio low. Further, in an image including only two primary colors among the three primary colors of RGB, it is possible to reduce the power consumption and perform arithmetic processing so as not to deteriorate the color reproducibility.

Note that one frame is divided into 6 subfields instead of 3 subfields, and (color 1, color 2, color 3,
Color 1, Color 2, Color 3). ． ． Alternatively, JP-A-8-248
By applying the display method disclosed in No. 381 (Color 1, Color 2, Color 3, Color 3, Color 2, Color 1). ． ． There is also a way to display.

(Second Embodiment) Next, a second color sequential display method of the present invention will be described in detail as a second embodiment with reference to the drawings. A specific part will be described as a driving method of the liquid crystal display device.

The color-sequential display method of the first embodiment is very effective for an image close to achromatic color, but as the image becomes rich in color that always uses the three primary colors, color reproducibility is improved. If the sacrifice is not made to some extent, the effect of reducing the color breakup is likely to decrease, so the method of using the white subfield and the color sequential display method of the first embodiment are used in combination. That is, as shown in FIG. 3A, the achromatic component is extracted from the video signal in all pixels. In the example of FIG. 3A, a method of subtracting the luminance equivalent of B having the minimum value in RGB from RG and assigning it to the achromatic component is adopted. After that, the same calculation as in FIG. 1 is performed to obtain color 1, color 2 and color 3, and color sequential display is performed as shown in FIG. The maximum luminance of all pixels is assigned to the achromatic component. In the color-sequential display of the second embodiment, as shown in FIG. 3B, the color 1, the color 2, and the color 3 are three.
Any two of the primary colors are mixed. As in the case of Embodiment 1, as shown in FIG. 4, the power consumption can be reduced by adjusting the brightness of the three primary color backlights to color 1, color 2 and color 3 in each subfield. At this time, the transmittance of the liquid crystal is relatively 1. Most preferably, the calculation should be repeated so that the volume of the parallelepiped is minimized for each frame period, and the backlight brightness and the transmittance of the liquid crystal cell should be controlled according to the calculation result.
This is similar to the case of the first embodiment.

By the method described above, it is possible to reduce color breakup and reduce power consumption to some extent even in a colorful image.
However, in the method of the second embodiment, 4 subfields are used.
In addition, since the achromatic color component is specially processed, the power consumption increases as compared with the method of the first embodiment.
This increase in power consumption is improved to some extent by setting an upper limit on the luminance ratio of the achromatic color component. It is shown in FIG.
As an example, the case where the upper limit of the ratio of the achromatic component is set to 70% is shown. The inventors have confirmed by subjective evaluation that even if the upper limit of the ratio of the achromatic color component is set to 70%, the deterioration of the image quality due to color breakage falls within an allowable limit.

Also in the second embodiment, as in the first embodiment, when a parallelepiped that includes all of the plotted points is set, the color information of the input video signal is accurately represented. It Of the set of plotted points,
By setting a parallelepiped that includes plot points at a predetermined ratio, the color breakage reduction effect can be enhanced.

In the first and second embodiments, the gamma correction process is not particularly described, but it is preferable to perform an appropriate gamma correction process according to the color light assigned to the subfield. Further, OCB mode liquid crystal is the most effective as a structure capable of realizing high-speed response capable of color sequential driving, but since OCB mode liquid crystal displays black in combination with a film, it is possible to achieve black level by color light assigned to subfields. The voltage fluctuates. Therefore, it is preferable to reset the black level voltage accordingly.

In conclusion, when the parallelepiped is reset for each frame, it is preferable to perform an appropriate gamma correction process and reset the black level voltage for each frame.

(Embodiment 3) Next, an embodiment of the display device of the present invention will be described in detail with reference to the drawings. This display device realizes the color sequential display method of the first embodiment. In addition, a specific part is described as a liquid crystal display device.

FIG. 6 shows a schematic view of the display device according to the third embodiment. The video signal input from the video input terminal 61 is temporarily stored in the video signal storage means 62 capable of storing one screen. Then, the calculation means 63 reads out the video signal of each pixel from the video signal storage means 62, and 3
Plot in the three-dimensional color stimulus space. Further, the calculating means 63
Sets a parallelepiped in the three-dimensional color stimulus space so that all plotted points are included according to a preset algorithm.
To decide. For the reason described in the first embodiment, it is preferable that the arithmetic means 63 reset the setting of the parallelepiped every frame period. Next, the determined color 1, color 2, and color 3 information and the color information of the plotted points are passed to the controller 64. The controller 64 responds to the received video signal by the source driver 6
6. Output a control signal to the gate driver 67. The control of the pixel 68 by the source driver 66 and the gate driver 67 is the same as that of the conventional liquid crystal display device.

The controller 64 also outputs a backlight control signal to the backlight control means 65. The backlight control unit 65 controls the backlight 69 based on the backlight control signal received from the controller, and the backlight 69 emits color 1, color 2 and color 3 in each subfield. As described in the first embodiment, it is more preferable that the controller 64 and the backlight control means 65 are provided with a means for operating them in synchronization with each other so that the brightness of the backlight is minimized. preferable.

Further, as described in the second embodiment, in the case of adopting the color sequential display method in which the achromatic color components are extracted in advance and then the plot is performed in the three-dimensional color stimulus space, the arithmetic means 63 is used. , Achromatic component extraction function must be added. In this case, the controller 64 and the backlight control means 65 need to have a function of displaying an achromatic component as a white subfield. Also in this case, the brightness of the backlight should be the minimum necessary,
It is more preferable that the controller 64 and the backlight control means 65 are provided with means for operating both in synchronization.

After extracting the achromatic component in advance, 3
When adopting the color sequential display method for plotting in the three-dimensional color stimulus space, the upper limit of the luminance of the achromatic component causes
It is possible to achieve a balance between the effect of reducing color breakup and power consumption. Therefore, as shown in FIG. 7, a luminance upper limit setting means 71 for an achromatic color component is added, which is opened to the user,
A configuration in which switching is possible according to the type of video is more preferable. Further, as shown in FIG. 8, the brightness upper limit automatic setting means 81 for automatically setting the upper limit of the brightness of the achromatic component by the video stored in the video signal storage means 62 according to a preset algorithm. The added structure is more preferable.

For mobile use, a built-in battery 9
When the remaining capacity of 1 is reduced, it is required to reduce power consumption even if the effect of reducing color breakage is sacrificed to some extent. Therefore, as shown in FIG. 9, the remaining capacity measuring means 92 of the built-in battery and the brightness upper limit automatic switching means 93 for switching the upper limit of the brightness of the achromatic component according to the measured remaining capacity.
Is preferably added. In addition, it has been clarified that the subjective value of color breakage changes depending on the ambient brightness. In bright places, color breakup tends not to be a concern. Therefore, as shown in FIG. 10, brightness measuring means 101 for measuring the brightness of the surroundings is added, and the upper limit of the brightness of the achromatic component is automatically switched according to the measured surrounding brightness. Means 102 are preferably added.

In the third embodiment, the case of setting a parallelepiped including all the points plotted in the three-dimensional color stimulus space has been described, but as described in the first embodiment, A display device capable of setting a predetermined ratio in advance and setting a parallelepiped that satisfies the predetermined ratio is preferable. As a configuration for realizing this, as shown in FIG.
It is preferable that the inclusion rate switching means 111 for the plot points is added and is open to the user. For example,
For users who are strict about color breakup, lower the inclusion rate of plot points and select settings that emphasize color breakup reduction. For users who are strict about color reproducibility, the inclusion ratio of plot points is improved to improve color reproducibility.
Such usage is assumed.

Further, as shown in FIG. 12, in accordance with a preset algorithm, the inclusion ratio of the plot points is automatically switched by the image stored in the image signal storage unit 62 so that the inclusion ratio automatically switches. 12
A configuration in which 1 is added is preferable.

For mobile use, the built-in battery 1
When the remaining amount of 31 decreases, it is conceivable to reduce the power consumption by sacrificing the color reproducibility to some extent. Therefore, as shown in FIG. 13, it is preferable that the remaining capacity measuring unit 132 and the inclusion ratio automatic switching unit 133 for switching the inclusion ratio of the plot points according to the measured battery remaining capacity are added. Extremely, an achromatic color or a single color display can be used.

Further, since the subjective evaluation of color breakage fluctuates according to the ambient brightness, the brightness measuring means 141 for measuring the ambient brightness and the inclusion of the plot points depending on the measured ambient brightness. It is preferable that the automatic inclusion ratio switching means 142 for plot points for automatically switching the ratio is added.

In the third embodiment, the weighting of each plot point when setting a parallelepiped is not particularly described, but when the predetermined ratio (inclusive ratio of plot points) is not 100%. As described in the first embodiment, the image quality can be improved by appropriately weighting each plot point. Therefore, as shown in FIG. 15, it is preferable that the weighting switching means 151 is added and is open to the user.

At least one is required for the color sequential display method.
It is necessary to divide the frame into three, and it is desirable to have a high-speed response in which the response is complete even in 1/3 of one frame period of 60 Hz. Therefore, the OCB mode liquid crystal using the nematic phase liquid crystal in the bend alignment is suitable. For example, it is preferable to use a normally white type liquid crystal cell and to use an OCB mode liquid crystal, an alignment film, a cell gap, and the like, in which the response from black display to white display at room temperature is 5.0 ms or less.
In OCB mode liquid crystal, the modulation factor is determined by the Δnd product and the phase compensation plate, so Δnd is 0.5 μm or more and 1.0 μm or more.
It is preferable to set the following. However, Δn is the refractive index anisotropy of the liquid crystal at room temperature at 589 nm, and d is the cell gap. According to the study by the inventors, it is particularly preferable that the liquid crystal used at this time has a bulk viscosity of 60 mPa · s or less at room temperature from the viewpoint of high-speed response. Further, if the voltage applied to the liquid crystal cell during black display is too low, the transition to the splay alignment state is likely to occur, and if it is too high, the load applied to the drive circuit increases, so it is preferably 4.5 V or more and 7.5 V or less. Furthermore, it is preferable to use a cyano-containing liquid crystal as a liquid crystal having a bulk viscosity of 60 mPa · s or less even if Δn is high. In order to achieve both low viscosity and reliability, the cyano content is 5% or more and 20% or more. % Or less is particularly preferable.

[0051]

As described above, according to the present invention, a remarkable reduction in color breakup can be expected depending on the image even in the three subfields, and the luminance component that is not effectively utilized can be reduced as much as possible. Therefore, the power consumption is reduced and the environmental load is small. Further, it can be applied to a display device driven by a built-in battery. further,
It is also possible to use it in combination with a conventional method of displaying in four subfields including an achromatic color component.

In conclusion, according to the present invention, it is possible to obtain a display device with less color breakup even by the color sequential display method and to spread the display device of the color sequential display method which can reduce the power consumption as compared with the conventional one. And contribute to the global environment and space environment.

[Brief description of drawings]

FIG. 1 is a conceptual diagram for explaining a first color sequential display method of the present invention.

FIG. 2 is a conceptual diagram showing backlight luminance and pixel transmittance in the first color sequential display method of the present invention.

FIG. 3 is a conceptual diagram for explaining a second color sequential display method of the present invention.

FIG. 4 is a conceptual diagram showing backlight luminance and pixel transmittance in the second color sequential display method of the present invention.

FIG. 5 is a conceptual diagram for explaining a case where an upper limit is set for the luminance of an achromatic component in the second color sequential display method of the present invention.

FIG. 6 is a conceptual diagram showing a configuration of a display device of the present invention.

7 is a conceptual diagram showing a configuration of a display device in which a luminance upper limit setting unit for an achromatic color component is added to the display device of FIG.

FIG. 8 is a conceptual diagram showing a configuration of a display device in which a luminance upper limit automatic setting unit for an achromatic color component is added to the display device of FIG.

9 is a conceptual diagram showing a configuration of a display device in which a built-in battery remaining capacity measuring means and an achromatic color component brightness upper limit automatic switching means are added to the display device of FIG.

FIG. 10 is a conceptual diagram showing a configuration of a display device in which a brightness measuring unit and a luminance upper limit automatic switching unit for an achromatic color component are added to the display unit of FIG.

11 is a conceptual diagram showing the configuration of a display device in which plotting point inclusion rate switching means is added to the display device of FIG.

12 is a conceptual diagram showing the configuration of a display device in which automatic inclusion ratio switching means for plot points is added to the display device of FIG.

13 is a conceptual diagram showing a configuration of a display device in which a built-in battery remaining capacity measuring means and a plot point inclusion rate automatic switching means are added to the display device of FIG.

FIG. 14 is a conceptual diagram showing a configuration of a display device in which a brightness measuring unit and a plot point inclusion rate automatic switching unit are added to the display unit of FIG.

15 is a conceptual diagram showing a configuration of a display device in which weighting switching means is added to the display device of FIG.

FIG. 16 is a schematic diagram showing a configuration of a display device of a conventional example.

[Explanation of symbols]

61 Video input terminal 62 video signal storage means 63 computing means 64 controller 65 Backlight control means 66 Source Driver 67 Gate driver 68 pixels 69 Backlight 71 Luminance upper limit setting means 81 Brightness upper limit automatic setting means 91 Built-in battery 92 Remaining capacity measuring means 93 Brightness upper limit automatic switching means 101 Brightness measuring means 102 Brightness upper limit automatic switching means 111 Inclusion ratio switching means 121 Automatic inclusion ratio switching means 131 Built-in battery 132 Remaining capacity measuring means 133 Automatic inclusion ratio switching means 141 Brightness measuring means 142 Automatic inclusion ratio switching means 151 Weighting switching means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 641 G09G 3/20 641E 641R 642 642F 642P 3/34 3/34 J 3/36 3/36 H04N 9/64 H04N 9/64 F (72) Inventor Shigeki Hirohata 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 2H093 NA16 NA65 NC41 NC71 ND17 ND24 ND39 5C006 AF63 AF64 BA19 BB29 BF01 BF39 EA01 FA29 FA47 GA03 GA04 5C060 AA07 BA04 BC01 DB13 JA30 5C066 AA03 CA08 DC00 GA01 KE01 KP02 5C080 AA10 BB05 CC03 DD01 DD12 DD26 EE19 EE29 GG08 JJ02

Claims (48)

[Claims] 1. A video signal for one screen in a color-sequential display method in which one frame period is divided into three subfields, and video of an arbitrary color is displayed in each of the three subfields to obtain a color video. A parallelepiped that includes a predetermined proportion of plotted points in the set of points in which the color information is plotted in the three-dimensional color stimulation space and that has the origin in the three-dimensional color stimulation space as one vertex, A color-sequential display method in which images of three colors corresponding to three sides extending from the origin of the parallelepiped are displayed in each of the three subfields. 2. The color sequential display method according to claim 1, wherein the volume of the parallelepiped in the three-dimensional color stimulus space is minimized for each frame period. 3. One frame period is divided into four subfields, one of the four subfields is a white subfield, and three other than the white subfield.
In the color-sequential display method for displaying an image of an arbitrary color in each subfield to obtain a color image, an achromatic component is extracted from an image signal for one screen, and an image of the achromatic component is extracted in the white subfield. Of the set of points in which the color information of the video signal obtained by removing the achromatic color component from the video signal is plotted in the three-dimensional color stimulus space, a plot point of a predetermined ratio is included, and A parallelepiped having an origin at one apex in a three-dimensional color stimulus space is obtained, and three color images corresponding to three sides extending from the origin of the parallelepiped are displayed in the three subfields, respectively. Display method. 4. The color sequential display method according to claim 3, wherein the volume of the parallelepiped in the three-dimensional color stimulus space is minimized for each frame period. 5. The color sequential display method according to claim 3, wherein an upper limit is set for the luminance ratio of the achromatic color component. 6. The color sequential display method according to claim 5, wherein the upper limit of the luminance ratio is 70%. 7. The predetermined ratio is less than 100%,
7. The color sequential display method according to claim 1, wherein the plot point that is not included is replaced with a point in the parallelepiped that is closest to the plot point that is not included. 8. The color sequential display method according to claim 7, wherein the parallelepiped is set by giving a predetermined weight to the plot points. 9. The color sequential display method according to claim 8, wherein the predetermined weighting is proportional to the x-th power of the distance from the origin of the plot point in the three-dimensional color stimulus space. However, x is a real number between 0 and 3 inclusive. 10. A light source of at least three primary colors of red, green and blue,
In a display device having a plurality of pixels arranged in a matrix on the front surface of the light source having means for independently controlling light transmittance, and means for inputting a video signal,
A frame period is divided into three subfields, and a driving method of a display device that obtains a color image by displaying an image of an arbitrary color in each of the three subfields. From the set of points plotted in the three-dimensional color stimulus space, a parallelepiped that includes a predetermined proportion of plotted points and has the origin in the three-dimensional color stimulus space as one vertex is obtained, and the three subfields are obtained. 3. A method of driving a display device, wherein images of three colors corresponding to three sides extending from the origin of the parallelepiped are displayed. 11. The method for driving a display device according to claim 10, wherein the volume of the parallelepiped in the three-dimensional color stimulus space is minimized every frame period. 12. The brightness of the three-primary-color light source and the transmittance of the pixel are controlled in synchronization so that the brightness of the three-primary-color light source becomes minimum according to the three-dimensional color stimulus space value of the color corresponding to the three sides. The method for driving a display device according to claim 10 or 11, characterized in that. 13. A light source of at least three primary colors of red, green and blue,
A method for driving a display device, comprising: a plurality of pixels arranged in a matrix on the front surface of the light source having means for independently controlling light transmittance; and means for inputting a video signal to the pixels, One frame period is divided into 4 subfields, one of the 4 subfields is a white subfield, and an image of any color is displayed in each of the 3 subfields other than the white subfield to display a color. A method of driving a display device for obtaining an image, comprising extracting an achromatic component from a video signal for one screen, displaying an image of the achromatic component in the white subfield, and extracting the achromatic component from the image signal. Of the set of points in which the color information of the removed video signal is plotted in the three-dimensional color stimulus space, a predetermined proportion of plotted points is included, and the original in the three-dimensional color stimulus space is included. The seek parallelepiped with the one vertex, a method of driving the display and displaying each of three colors of the image corresponding to the three sides extending from the origin of the parallelepiped at the 3 sub-fields. 14. The method of driving a display device according to claim 13, wherein the volume of the parallelepiped in the three-dimensional color stimulus space is minimized every frame period. 15. The luminance of the three primary color light sources and the pixel are set so that the luminance of the three primary color light sources becomes minimum according to the luminance of the achromatic color component and the three-dimensional color stimulus space value of the color corresponding to the three sides. 15. The method for driving a display device according to claim 13 or 14, wherein the transmittances are controlled in synchronization with each other. 16. The method for driving a display device according to claim 13, wherein an upper limit is set for the luminance ratio of the achromatic color component. 17. The method for driving a display device according to claim 16, wherein the upper limit of the luminance ratio is 70%. 18. The non-enclosed plot point is replaced by a point in the parallelepiped closest to the non-enclosed plot point, wherein the predetermined ratio is less than 100%. 18. The method for driving a display device according to any one of 1 to 17. 19. The parallelepiped is set by weighting the plot points with a predetermined weight.
8. A method for driving a display device according to item 8. 20. The method for driving a display device according to claim 19, wherein the predetermined weighting is proportional to the x-th power of the distance from the origin of the plot point in the three-dimensional color stimulus space. However, x is a real number between 0 and 3 inclusive. 21. A light source of at least three primary colors of red, green and blue,
A plurality of pixels arranged in a matrix on the front surface of the light source having means for controlling light transmittance independently of other pixels, means for inputting a video signal, and storing the video signal for one screen And a three-dimensional color stimulus that includes a predetermined proportion of the plot points in a set of points in which the video signal stored in the storage means is plotted in a three-dimensional color stimulus space. A calculation means for obtaining a parallelepiped having an origin in one space and a brightness of the light source are controlled independently for each of the three colors of red, green and blue, and one frame period is divided into three subfields. A display device, comprising: a light source control unit for emitting three colors corresponding to three sides extending from the origin. 22. The display device according to claim 21, wherein a minimization unit that minimizes a volume of the parallelepiped in the three-dimensional color stimulus space is added for each frame period. 23. The brightness of the three primary color light sources and the transmittance of the pixel are controlled synchronously so that the brightness of the three primary color light sources is the lowest according to the three-dimensional color stimulus space value of the color corresponding to the three sides. 23. The display device according to claim 21, further comprising a synchronization control unit. 24. A light source of at least three primary colors of red, green and blue,
A plurality of pixels arranged in a matrix on the front surface of the light source having means for controlling light transmittance independently of other pixels, means for inputting a video signal, and storing the video signal for one screen And a color information of the video signal obtained by removing the achromatic color component from the video signal stored in the storage means, and extracting the achromatic color component from the video signal stored in the storage means.
Calculating means for obtaining a parallelepiped having a predetermined proportion of plotted points in the set of points plotted in the three-dimensional color stimulus space and having the origin at one vertex in the three-dimensional color stimulus space; A display device comprising: a coloring component; and a light source control means for causing three colors corresponding to three sides extending from the origin of the parallelepiped to emit light in four subfields obtained by dividing one frame period into four. . 25. The display device according to claim 24, wherein a minimization unit that minimizes the volume of the parallelepiped in the three-dimensional color stimulation space is added for each frame period. 26. According to the luminance of the achromatic color component and the three-dimensional color stimulus space value of the color corresponding to the three sides, the luminance of the three primary color light sources and the pixel are adjusted so that the luminance of the three primary color light sources becomes minimum. 26. The display device according to claim 24 or 25, further comprising synchronization control means for controlling the transmittance in synchronization. 27. An upper limit setting means for setting an upper limit to the luminance ratio of the achromatic color component is added.
The display device according to any one of 1. 28. The display device according to claim 27, wherein the upper limit of the luminance ratio is 70%. 29. The display device according to claim 27, further comprising an upper limit switching unit for switching an upper limit of the luminance ratio by a user. 30. The measuring means for measuring the remaining capacity of the built-in battery, and the upper limit automatic switching means for automatically switching the upper limit of the luminance ratio according to the remaining capacity of the battery are added. The display device according to any one of claims. 31. A means for measuring the brightness of a use environment,
31. The display device according to claim 27, claim 29, or claim 30, further comprising an automatic switching unit that automatically switches the upper limit of the luminance ratio according to the brightness. 32. Plot point substitution means for substituting the plot point not included at a point in the parallelepiped closest to the plot point not included is provided. The display device according to any one of claims 21 to 31. 33. The display device according to claim 32, further comprising weighting means for setting the parallelepiped after performing predetermined weighting on the plot points. 34. The display device according to claim 33, further comprising switching means for switching the predetermined weighting by a user. 35. The method according to claim 33, wherein the predetermined weighting is proportional to the x-th power of the distance from the origin of the plot point in the three-dimensional color stimulus space.
4. The display device according to any one of 4. However, x is 0 or more 3
The following real numbers. 36. The display device according to claim 21, further comprising a plotting point inclusion rate switching means for switching the predetermined rate by the user. 37. The display device according to claim 21, further comprising automatic plotting point inclusion rate automatic switching means for automatically switching the predetermined rate depending on a display image. 38. A measuring means for measuring the remaining capacity of the built-in battery, and a plot point inclusion rate automatic switching means for automatically switching the inclusion rate of the plot point according to the battery remaining capacity. 35. The display device according to any one of 35 to 35. 39. A means for measuring the brightness of a use environment,
The display device according to any one of claims 21 to 35, further comprising automatic plotting point inclusion rate automatic switching means for automatically switching the inclusion rate of the plot point according to the brightness. 40. The display device according to claim 21, wherein the display device is a display device using liquid crystal cells for pixels.
9. The display device according to any one of 9. 41. The display device according to claim 40, wherein the liquid crystal is a nematic phase and is an OCB mode liquid crystal that is bend-aligned during image display. 42. The liquid crystal cell is a normally white type, and the response time from black display to white display at room temperature is 5.
The display device according to claim 41, wherein the display device has a duration of 0 ms or less. 43. The product of the refractive index anisotropy Δn at room temperature of the liquid crystal at 589 nm and the cell gap d Δn · d is 0.5 μm or more and 1.0 μm or less. 42. The display device according to any one of 42. 44. The bulk viscosity of the liquid crystal at room temperature is 60.
44. The display device according to claim 41, wherein the display device has a mPa · s or less. 45. The display device according to claim 42, wherein an applied voltage during black display of the liquid crystal cell is 4.5 V or more and 7.5 V or less. 46. The display device according to claim 41, wherein the liquid crystal is a cyano-containing liquid crystal. 47. The display device according to claim 46, wherein the cyano content is 5% or more and 20% or less. 48. The screen is divided into a plurality of areas,
22. A display device in which the light source is installed in each of the areas, comprising a surface division processing means for independently processing the video signals for the respective areas as the video signals for the one screen. 48. The display device according to any one of 47 to 47.