JP2001296851A - Device and method for displaying picture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for setting frequency conditions under which the color slurring which occurs when an observer is turning his/her eyes to follow a moving picture is not disturbing to the observer, to provide a setting method for reducing blurring of motion and a multiple image, and to provide a method and device for displaying a picture capable of displaying a high quality dynamic image using those methods. SOLUTION: In the device and method for displaying a picture for periodically and sequentially displaying colors in a time-division manner, when a field frequency is expressed as F [Hz], a visual angle speed of the moving picture as ω [deg./s], the eyesight of the observer watching the moving picture by S, and an inverse number of a ratio of one cycle color display in one field period as m (m is a positive real number), the color display frequency Fcolor [Hz] of one cycle by the number of display colors C is set so as to satisfy the following expression (1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display apparatus and an image display method for displaying a field-sequential image, and more particularly, a viewer follows a motion image displayed on a video display apparatus for performing a time-division color display. The present invention relates to an image display apparatus and an image display method using a method for improving the disturbance of moving image quality due to color misregistration, multiple images, and motion blur that occur when performing image display.

[0002]

2. Description of the Related Art Conventionally, a so-called CRT (Cathode-Ray Tube) display using a cathode ray tube has been generally used as an image display device. As a projector-type optical image projection display device that displays an image in a display format different from that of a CRT display, there are a liquid crystal projector using a liquid crystal element in an optical shutter portion and a projector using a finely processed optical reflection element. .

In the method of using light of the projector, a so-called three-plate method in which three primary colors of light are separated in a spatial direction, input to an optical shutter element assigned to each color, and output light is synthesized and projected, A so-called field-sequential (field-sequential) in which three primary colors of light are separated in the time direction, input to a single-plate optical shutter element, and output light is sequentially projected.
quential) method. It is used for applications such as simplification of the structure by each display method and applications such as increasing the resolution.

[0004]

By the way, research on time-division color display (field sequential) has been studied.
999 Annual Meeting of the Institute of Image Information and Television Engineers (ITE '99: Ann
ual Convention) As shown in Proceedings 12-2 and 12-3, a field-sequential LCD is simulated using a CRT display device capable of displaying at 8 × speed, and the mechanism of color misregistration is examined. Studies have been conducted on the conditions under which color misregistration occurs by synchronizing the color display output with a portable projector by time.

[0005] When colors are displayed in a time-division manner, the visibility of the color misregistration is determined by the moving speed of the moving image to be visually recognized and the one of RGB colors.
It has been clarified in the previous studies that it depends on the length of the periodic display period, but it has not been sufficiently clarified how far the actual device should be. In addition, it is foreseeable that a multiplex image or motion blur will occur at the time of display by the above setting, but a method of improvement or the like has not been clarified so far.

The present invention has been made in view of such a problem, and occurs in an image display system that performs time-division color display when a viewer moves his / her eyes following a moving image. Provided are a method for setting a frequency condition in which color shift is not a concern, a setting method for reducing motion blur and multiple images, and an image display device and an image display method capable of displaying a high-quality moving image using those methods. It is an object.

[0007]

According to the present invention, there is provided an image display apparatus and method for displaying display colors periodically in a time-division manner.
z], visual angle velocity ω [deg./
s], the visual acuity S of the observer watching the moving image, and when the reciprocal of the ratio of one cycle of color display in one field period is m (m is a positive real number), one cycle of the display color number C By setting the color display frequency Fcolor [Hz] so as to satisfy the following expression, it is possible to perform a moving image display in which a color shift due to a visual line following a moving image does not matter.

[0008]

(Equation 7)

Further, the image display apparatus and method according to the present invention
When the color display frequency Fcolor of one cycle based on the display color number C exceeds 150 Hz, the color display frequency Fcolor is set to a frequency that satisfies the following equation. It becomes possible to set so that it does not become.

[0010]

(Equation 8)

Further, the image display apparatus and method according to the present invention
When the color display frequency of one cycle is Fcolor, the field frequency is F, and the number k of repeated color display in the field is k (k is a natural number), the color display period Tdisp in the field is expressed by the following equation. Is satisfied, it is possible to reduce the occurrence of multiple images and motion blur due to repeated display of the color cycle.

[0012]

(Equation 9)

Further, the image display method of the present invention provides a visual angle velocity ω and a visual acuity S of a viewer when a moving image is tracked by a line of sight.
By using the parameters in the respective ranges as input values and calculating the color display frequency Fcolor of one cycle based on the number of display colors C and the number k of repetitive displays of periodic color display in a field, various small-sized displays are realized. It is possible to set the driving conditions required for display devices and large-screen image display devices,
This facilitates design when displaying images with moving image quality in which color shift, motion blur, and multiple images are not bothersome.

Since the display device designed with the driving parameters obtained by the above configuration can be appropriately set according to the screen size and application, it is possible to provide an image display device capable of displaying a high-quality moving image. In addition, it is possible to perform arbitrary display according to the set value for the visual angular velocity ω of the motion image that can be imagined and the visual acuity S of the observer, and the parameters in each range, so that it is set in advance. It is possible to compare and evaluate the displayed images.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an image display device and an image display method according to the present invention will be described below in detail with reference to the accompanying drawings. First, the basic principle of the present invention will be described. A description will be given of a calculation method for setting a color shift (color break) generated when a line of sight follows a moving image when one field period is color-displayed in a time-division manner.

FIG. 1 is a view showing a visual angular velocity when a moving image is followed by a line of sight with respect to a distance from a video display surface. As shown in FIG. 1, when a moving image is line-of-sight following a distance n times the screen height H from the display device, the average visual angular velocity ω [deg./s] is expressed by the following equation (1) or the following equation: (1 ').

[0017]

(Equation 10)

Here, F is the field frequency [Hz], H
Is the number of pixels in the height direction of the display screen [pixel], n is a number representing the viewing distance, a multiple based on the screen height, π is the pi,
v is the number of motion pixels [pixel] per field.
In many conventional reference papers and the like, the motion visual angular velocity ω [deg./s] is expressed by Expression (1 ′). In this case, when the screen of the display device is a 360-degree panorama and the viewer is in the center, it can be said that the expression is correct,
In a general flat display device, the viewing angle speed is less than 180 [deg./s], no matter how fast the display moves, and no matter how the viewer takes the distance to the screen.

For this reason, since the expression (1 ') is not appropriate in terms of expression, the case of the expression (1) is applied in the subsequent calculations. However, as shown in FIG. 9, the deviation of the value of the expression (1) from the expression (1 ′) is sufficiently small since it is 2.5% or less if the visual angular velocity is within 30 [deg./s]. Within this range, there is no problem in citing the data of the conventional literature as it is.

FIG. 2 is a motion model diagram for explaining a visible luminance distribution that can be visually recognized when a line of sight follows a moving image in a display device that performs color display in a time-division manner. FIG. 3 is a motion model diagram for explaining a visible luminance distribution that can be visually recognized when a line of sight follows a motion image in a display device having a normal stripe pixel structure. It is a schematic diagram of an image which can be visually recognized when following a line of sight to a motion image. 2 and 3, the display state of each pixel per unit time is shown in the time axis direction, and the spatial arrangement of pixels on one horizontal line on the display surface is shown in the pixel axis direction.

Here, the locus when the observer follows the line of sight from left to right with respect to the display image represents the axis of the line of sight in the drawing. According to the visual luminance space distribution diagram that the viewer may perceive, as the line of sight follows the moving image, the color shift is more conspicuous than the motion blur in FIG. 2 and the motion blur in FIG. It is suggested that is more noticeable than the color shift. In the arrangement shown in FIG. 1, consider a color shift as shown in FIG.
Assuming that the average color shift (color break) viewing angle is CB [min.], The color shift viewing angle CB is expressed by the following equation (2).

[0022]

[Equation 11]

Here, v 'is an image fogging amount [pixel] due to a line of sight following a moving image in a field,
Assuming that the reciprocal of the one-period ratio of the RGB display in the field is m, v ′ has a relationship with v and m according to the following equation (3).
In other words, if the RGB display is performed repeatedly, it is equivalent to performing the RGB display m times within one field period, in other words, it can be considered as a double speed number. v ′ = v / m (3) Therefore, the expression (2) becomes the following expression (4).

[0024]

(Equation 12)

From equation (1), the number of motion pixels v is represented by the following equation (5). Using equations (4) and (5), the color break viewing angle CB [min. ]
It is represented by the following equation (6).

[0026]

(Equation 13)

On the other hand, from the equation (6), the RGB display frequency Fcolor [Hz] of one cycle is given by the following equation (7).

[0028]

[Equation 14]

According to the Science Dictionary compiled by the Japan Science Foundation, the definition of static visual acuity S is given by the following equation (8). S = 1 / θ (8) Here, the above θ [min.] Represents the minimum visual angle that can be resolved by the visual acuity of the viewer. For example, if θ ≦ 1.43 [min.], The static visual acuity S ≧ 0.7 (the visual acuity for driving a car).

FIG. 4 is a model diagram for explaining a viewing angle at which colors can be viewed separately and independently. The visual angle at which the color misregistration cannot be visually recognized independently at the time of the RGB display is the color break visual angle equation (6), where the visual angle of each of the separated RGB colors is equal to or less than the decomposition visual angle θ in the visual acuity of the viewer.
That is, in the arrangement shown in FIG. 4, the following expression (9) may be satisfied.

Θ ≧ CB / 3 (9) If this condition is satisfied, it becomes difficult to distinguish each of the RGB color shifts on the display independently, and subjectively, the color shifts are mixed. Will be visible. Here, in equation (9), the display color is RGB 3 in the time axis direction.
Since the colors are colors, the average color shift viewing angle per color is divided into three equal parts in terms of the number of colors. If there are C types of display colors in the time axis direction per cycle, equation (9) becomes , (9 ').

Θ ≧ CB / C (9 ′) In fact, the matter shown by the equations (9) and (9 ′) is “two distances apart” as shown in the model diagram shown in FIG. A thing that does not know that there are two (conditions when it is an inequality sign), or barely appears to have two things (when it is an equal sign) Is not a distinction.

FIG. 5 is a model diagram for explaining a viewing angle at which mixed colors can be visually recognized separately. However, if the above equations (9) and (9 ′) are satisfied, as shown in the model diagram of FIG. 5, the color shift reaches the eyes of the viewer according to the respective light emission distributions, so that the colors are mixed. It is suggested to be visible in the state.

The visual color at this time is "whether or not to be worried".
The present inventor made an evaluation from the viewpoint that, at a relatively low color display frequency Fcolor [Hz], the result is that the viewing angle is half of the viewing angle at which the shape can be resolved by the visual acuity of the viewer is near the boundary. was gotten. This corresponds to the limit value of the viewing angle in which each color of the mixed color shift in FIG. The evaluation process for this is described in detail in the first embodiment.

From the above, if the following equation (10) is used for the generalized equation (9 '), it is possible to obtain a condition in which the color shift is reduced to a level that does not matter. θ ≧ CB / 2C (10) Expressions (8), (7), and (10) corresponding to visual acuity and visual angle
Thus, the color display frequency Fcolor is such that the viewer of visual acuity S does not care about the color shift with respect to the moving image at the visual angular velocity ω.
[Hz] is given by the following equation (11) if the number of colors C = 3.

[0036]

(Equation 15)

When the display with the number of colors C is generalized, the following equation (12) is obtained.

[0038]

(Equation 16)

Alternatively, for equation (9 '), the following equation (13) is obtained.

[0040]

[Equation 17]

FIG. 6 is a diagram showing the lower limit of the display frequency at which the color misregistration cannot be visually recognized for each visual acuity, according to the moving speed of the image. FIG. 7 is a diagram showing the lower limit of the moving speed of each image. FIG. 7 is a diagram illustrating a lower limit value of a display frequency at which a color shift cannot be visually recognized according to a visual acuity of a viewer.

Graphs corresponding to the above equation (11) are shown in FIGS. The figure shows a case where the visual acuity S is fixed and the visual angular velocity ω is changed, and a case where the visual acuity S is fixed and the visual acuity S is changed. From these figures, it can be seen that the higher the visual acuity and the higher the visual angular velocity ω, the higher the minimum frequency at which color shift is not a concern.

Here, according to the dynamic visual acuity characteristics described on page 44 of the Television Image Information Engineering Handbook (1990 edition) issued by Ohm Publishing Co., it is known that the dynamic visual acuity changes as shown in FIG. 10 depending on the moving speed. . FIG.
It is a figure which shows the relative visual acuity of a moving-body visual acuity. If a function of the relative visual acuity α (ω) is defined with respect to the visual angular velocity ω, Expression (12) becomes the following Expression (14) when the visual acuity at rest is S.

[0044]

(Equation 18)

At this time, the range of the relative visual acuity function is 0 <α.
(Ω) ≦ 1. The following equation (15) is obtained for the equation (9 ′).

[0046]

[Equation 19]

Using the equations (12) to (15), the designer of the display device determines the multiple speed m of the color display period per field and the field frequency F, the movement speed ω of the display image, and the visual acuity S of the viewer. Can be set to a value that does not bother the color misregistration according to the range of. Since this calculation method does not depend on the resolution or screen size of the display device, it can be applied to a field sequential image display device of various resolutions and screen sizes.

Further, the designer of the display device designates the viewer to view the viewing distance from a certain distance or more, and an appropriate setting is made so as not to cause a color shift according to the appearance frequency of the moving speed of the output video. The display device can be designed with various setting values.

In this calculation method, the case where the display colors of the time-division color display are performed with the three primary colors RGB (red, green, and blue) of the emission color is exemplified. However, the primary colors are not limited to only RGB. For example, in order to clearly display a memory color such as a flesh color, orange (Orange) is added as a primary color, and ROG is added.
In the case of displaying B4 color in one unit in a time-division manner, it is possible to cope by setting C = 4 in each formula, or time-division display of three primary colors of absorption color YMC (yellow, magenta, cyan) and the like. In such a case, the same method can be applied. In this case, since there are three colors, it is sufficient to set C = 3.

Further, according to the equations (12) to (15), it can be seen that the frequency at which color shift does not matter becomes lower when more primary colors are displayed. Thus, if high-frequency output display of each color becomes possible, it is possible to design a display device that does not care about color shift even if the color display frequency Fcolor of one cycle is low.

On the other hand, with the set value of the color display frequency Fcolor at which the color misregistration obtained by applying the above-described method is not noticeable, the contour of a fast moving image is obtained when color display is repeated k times in one field. The part may be perceived as k multiplex images and felt as strong image degradation.

Here, if a set value is set such that the value of k becomes larger, the above-mentioned multiple images are more multiplexed and visually perceived as motion blur instead of multiple images. In order for the multiplexed image to appear connected at a value such as ω = 24.0 deg./s where the motion speed is large, k needs to be a large value exceeding 10 at a field frequency F = 60 Hz. The above can be easily derived from the following equation (17) by solving the following equation (16) for the visual acuity of the observer in equation (7) and solving for S = 1 / CB... (16) m. .

[0053]

(Equation 20)

Here, the reciprocal (or double speed value) m of the color display period ratio of one cycle is a real value, and corresponds to the maximum value of the number k of repeated displays. Therefore, k must always be set to be equal to or less than m. In practice, m is set to a relatively small value of about 10 or less due to the configuration of the driving circuit. However, with respect to the outline of a moving image, multiple images are connected at a portion where motion is slow, resulting in motion blur. It is perceived, and it is foreseen that it will be perceived as a multiple image in a fast-moving part. Therefore, as compared with FIGS. 2 and 3, the problem of motion blur of a motion image also becomes a problem again.

Since the motion blur becomes more remarkable as the display period in the field becomes longer, it is necessary to set the motion blur as short as possible. However, the display period is the color display frequency Fcolor
It cannot be shorter than the period set in [Hz]. For this reason, it is necessary that the set value for measures against motion blur and multiple images be at most shorter than one field period and longer than at least the display period determined by the color display frequency Fcolor [Hz]. That is, if the field frequency is F and the display period is Tdisp, the following equation (18) is obtained.
It is necessary to set as follows.

[0056]

(Equation 21)

Here, k is a natural number, which corresponds to actually performing color display k times in a field. For example, a field frequency F = 60 Hz (16.67 ms)
On the other hand, when Fcolor = 150 Hz, the conditions at k = 1 and k = 2 can be set according to Expression (18). The meaning of Fcolor = 150 Hz will be described later with reference to the first embodiment.

From this, Tdisp is 6.67 m, respectively.
s (display rate of 40%) and 13.33 ms (display rate of 80%) can be set, but when k = 1, the brightness of the entire display is reduced, and when k = 2, it is fast. There is a possibility that a double image is perceived in the contour portion at the time of the movement speed. If the brightness of the display screen can be sufficiently ensured even if the display period is shortened, a set value in a period as short as possible may be adopted.

Further, if the visual angular velocity ω can be set to a sufficiently small range, and the multiple images do not visually disturb, even if multiple images occur, the brightness is further ensured. Therefore, the display period may be set to be as long as possible. By using such a setting method, it is possible to reduce motion blur of a motion image and interference with a multiplex image in field sequential driving.
Hereinafter, embodiments of the present invention will be described in detail according to the above basic principle.

First Embodiment A display device that sequentially performs RGB display in a time division manner is used to
The display frequency of the B1 cycle is 53.3 Hz, 80.0 Hz,
At 160 Hz and 160 Hz, the measurement of the distance at which the user was not bothered by the color shift when moving and displaying the geometric figure at a constant speed, and the measurement of the static visual acuity at that distance were performed on 10 subjects.

The geometric figure is a rectangular scroll bar whose inside becomes the brightest or darkest, and its long axis is positioned vertically with respect to the screen, and reciprocates horizontally and periodically.
As the background, an image was used in which the luminance was changed stepwise in the vertical direction of the screen at the gradation value scaled to 11 gradations. By using such a figure, it is possible to indirectly know the level of the luminance difference when it is assumed that the color misregistration is not a problem, and to increase the reliability of the evaluation result.

In the measurement, in the case of a subject with low visual acuity, a color shift may be perceived even if the shape of the moving object is blurred from a distant distance so that the shape cannot be recognized. Has instructed that the viewing distance be specified as "a color shift can be seen in the range in which the shape of the moving object can be understood, but the image can be considered uninteresting." In the evaluation experiment, the parameters that can be set are the display frequency Fcolor of one cycle of color, the number of colors C, and the moving speed V per field of the geometric figure used as the image.

The measurement data is a distance L at which the user is not bothered by color misregistration and a static visual acuity S at the position, and the visual angular velocity ω of the moving image at the distance L is calculated. When the data is edited, the moving average value is obtained and displayed in a graph because there is variation in each measurement point. Here, in order to associate the measurement result with Expression (13), Expression (13) is modified, and this modified expression is defined as Expression (a).

[0064]

(Equation 22)

That is, according to the expression (a), the range of the static visual acuity in which the color shift with respect to the visual angular velocity ω does not matter in the display at the color display frequency Fcolor is shown. If the measurement result satisfies the relationship of Expression (a), Expression (13) can be used in designing the driving frequency of the display device.

FIGS. 10 to 12 show the case where the number of colors C = 3,
It is a figure which shows each measurement result by 10 test subjects in each color display frequency Fcolor, FIG.
FIG. 11 is a diagram showing the relationship between the visual angular velocity and the visual acuity of the observer who do not care about the color shift at 3.3 Hz. FIG. 11 shows Fcolor = 80.0 Hz.
FIG. 12 is a diagram showing the relationship between the visual angular speed and the visual acuity of the viewer at Fcolor = 160 Hz where the color misregistration at Fcolor = 160 Hz is not bothersome. . In order to make the distribution of data clearer, a plot on the right side by equation (a) and a plot on the right side by equation (b) below using equation (15) are shown.

[0067]

(Equation 23)

According to FIGS. 10 to 12, when the color display frequency is relatively low, the measurement points are determined by the above equations (a) and (b).
Is located between the plots. This means that “the condition of equation (a) needs to be satisfied, but the condition of equation (b) does not have to be satisfied”. In FIG. 12, which is a result of a higher frequency, the positions of the measurement plots are scattered near the plot for the equation (b).

This result means that "at least the condition of equation (a) must be satisfied and the condition of equation (b) is better satisfied". This means that it is necessary to satisfy Expressions (14) to (15) in a higher frequency range.

From the above evaluation results, in the field sequential drive type display device, when determining the color display drive frequency of one cycle under the condition that the color shift caused by the visual line following the moving image is not bothersome, 150
Equations (12) to (13) are set when the color display frequency is set to be as low as about Hz, and Equations (14) to (15) are set when the color display frequency is set to be as high as about 150 Hz or more. By setting satisfying conditions, a high-quality display device can be provided.

Here, the color display frequency Fcolor is 150H
The meaning of exceeding z will be described. The color display frequency Fcolor = 150 Hz was found by the present inventor from measurement results using the display frequency, the visual angular velocity, and the visual acuity of the observer as parameters. 10 to FIG. 12. That is, in the measurement results of FIGS. 10 to 12, the actual measurement points when the equation (a) is applied are indicated by broken lines, and the actual measurement points when the equation (b) is applied are indicated by solid lines.
For example, in the measurement result of Fcolor = 53.3 Hz in FIG. 10, the actual measurement point (see a circle) is almost located between the line of Expression (a) and the line of Expression (b). The actual measurement point shifts toward the line of equation (b) as the display frequency Fcolor increases, and Fcolor = 160 Hz in FIG.
In the measurement result of (1), the actual measurement point is located near the line of the equation (b).

The condition that “color shift is not a problem” is
It has been obtained that at least equation (a) must be satisfied, and under stricter conditions, it is sufficient to satisfy equation (b). Comparing the strictness of “Is it worried about color misregistration?”, Equation (b) is more severe than equation (a). For example, if the visual angular velocity is 6 deg./s in the measurement result of Fcolor = 53.3 Hz in FIG. If it's low, you can be bothered. However, if a person with a visual acuity of 1.5 sees the above image, the image is plotted on the upper side of the equation (a), so that the color shift is anxious. It is necessary to increase the color display frequency so that a person with this visual acuity 1.5 does not feel a color shift in the image of the moving speed. Such a situation is the case shown in FIG. In FIG. 12, it can be seen that the result of "I do not mind color misregistration" obtained from the experiment satisfies the condition of Expression (b) from the condition of Expression (a). Since a general motion image frequently occurs at about 10 deg./s or less, the higher the frequency is displayed, the more satisfactorily the expression (b) is satisfied.

The experimental results (53.3 Hz, 8
0.0 Hz, 160 Hz) and the display frequency of a general image (about 60 Hz), the color display frequency (120 Hz) which is twice the display frequency of the general image does not reach the expression (b), and the color display frequency is three times. It can be seen that the color display frequency (180 Hz) is too much. From this viewpoint, the color display frequency Fcolor
Is set to 150 Hz which is 2.5 times the display frequency of a general image. Therefore, the color display frequency Fcolor is set to, for example, 14
Although it is possible to set the frequency to 5 Hz, if the frequency of the color display frequency is made smaller, the condition becomes weaker.
= 150 Hz or more, the color misregistration that most people did not feel may be felt as soon as Fcolor = 145 Hz. Therefore, the color display frequency Fcolor is 1
00 Hz to 200 Hz (more preferably, Fcolor =
Color display frequency Fcolo
The frequency is set so that r satisfies Expression (13). The image display device that satisfies the expression (13) is, for example, a case where there is a situation where a large screen is viewed in close proximity (a screen of a movie theater or a game screen) or a very fast moving image (such as a sports competition) that can be tracked by eyes For example, the present invention can be universally applied to a display device in which the viewing angle speed of a motion image becomes relatively large.

Second Embodiment When color display is performed in a time-division manner, the color display frequency of one cycle within a range in which color shift is not a problem can be easily obtained from equations (12) to (15). . Here, the Journal of the Institute of Television Engineers of Japan, Vol. 40, No. 1 (1986), p. 46-53 or the same magazine, Vol. 40, No.
4 (1986), from P266-273, the visual angular velocity that can follow the motion velocity is 0 ≦ ω ≦ 24 deg./s, and the visual acuity of a general viewer is 1.0 ≦ S ≦ 1.5. Then, the one-cycle color display frequency Fcolor that does not cause color misregistration according to the above equations (12) to (15) displays three primary colors of RGB, so that the number of colors C = 3, and from equation (12), Fcolor ≧ 244 to 365 [Hz] From equation (13), Fcolor ≧ 487 to 731 [Hz].

Referring to the first embodiment, the result of equation (13) is adopted because the result of equation (12) is at least 150 Hz or more. From this, if the RGB display is performed at a display speed of at least 487 Hz, that is, at least about 8 times the field frequency of the general display device,
It is possible to provide a display device in which a color shift does not matter in a moving image having a moving speed of up to 24 deg./s.

Third Embodiment On the other hand, it is known that the dynamic visual acuity is lower than the static visual acuity depending on the moving speed, and the above is extracted from the dynamic visual acuity characteristics described in P44 of the Television Image Information Engineering Handbook (1990 version). As shown in FIG. 8, at 24 deg./s, which is the maximum movement speed that can be followed, the relative visual acuity is about 65%. In such a case, if the general visual acuity of the observer at rest is 1.0 ≦ S ≦ 1.5, the dynamic visual acuity is 0.65 ≦ S ′ ≦ 0.975 at the maximum speed of 24 deg./s. Becomes The color display frequency Fcolor of one cycle of RGB that does not cause color shift in the visual acuity in this range is Fcolor ≧ 158 to 238 [Hz] from the equation (14) and Fcolor ≧ 317 to 474 [Hz]. Referring to the first embodiment, the above equation (1)
Since the result of 4) is at least 150 Hz or more, the result of Expression (15) is adopted.

From the above, if the RGB display is performed at a display speed of at least 317 Hz or more, that is, about 5 times or more of the field frequency of the general display device, the movement speed becomes 24 deg./s.
It is possible to provide a display device in which color shift is not bothersome in moving images up to the above. Fourth Embodiment In general, the moving speed of a standard moving image is HDTV.
3 to 15 deg./s at the standard viewing distance 3H of the display device
It is about. In such a case, it is assumed that the dynamic visual acuity of the viewer does not decrease due to the movement speed, and the general visual acuity is 1.0 ≦
When S ≦ 1.5, and when the movement speed is set so as not to cause color shift up to 15 deg./s, RGB1
From the equation (12), the color display frequency Fcolor of the cycle is Fcolor ≧ 151 to 226 [Hz]. From the equation (13), Fcolor ≧ 302 to 452 [Hz].

Referring to the first embodiment, the result of the above equation (12) is at least 150 Hz or more, so the result of the equation (13) is adopted. Therefore, if RGB is displayed at a display speed of at least 302 Hz or more, that is, at least about 5 times the field frequency of a general display device, a display device that does not care about color shift in a moving image having a motion speed of up to 15 deg./s. Can be provided.

Fifth Embodiment With respect to the fourth embodiment, in consideration of a decrease in the dynamic visual acuity, the relative visual acuity is about 75% at a moving speed of 15 deg./s. In such a case, assuming that the general static visual acuity of the observer at rest is 1.0 ≦ S ≦ 1.5, the dynamic visual acuity is 0.75 ≦ S ′ ≦ at a motion speed of 15 deg./s.
1.125. The color display frequency Fcolor of one cycle of RGB that does not cause color shift in visual acuity in this range is Fcolor ≧ 113 to 170 [Hz] from Expression (14) and Fcolor ≧ Fcolor from Expression (14), assuming that the number of colors is C = 3. 226 to 339 [Hz].

Referring to the first embodiment, since the result of the above equation (14) is about 150 Hz, the setting becomes delicate. However, at least a frequency higher than the maximum value of the result of the equation (14) is selected. If there is no problem. Therefore, if RGB is displayed at a display speed of at least 170 Hz, that is, at least about three times the field frequency of a general display device, a display device that does not care about color shift in a moving image having a motion speed of up to 15 deg./s. Can be provided. Sixth Embodiment In this embodiment, a set value of a color display frequency of one cycle of RGB is obtained in a case where a relatively small display device is driven in a field sequential manner.

Generally, a portable display device having a screen of about several inches in diagonal width often sees the display screen within a reachable range, and thus the viewing distance is 30 cm regardless of the screen size.
From about 100 cm. At this time, when a motion image in which a motion generally occurring at a distance three times the screen height becomes 15 deg./s is viewed at another distance, the visual angular velocity changes as shown in [Table 1]. . Table 1 shows that the visual angular velocity is 1 at the 3H distance.
It is a table | surface which shows the visual angular velocity in each distance at the time of 5.0 deg./s.

[0082]

[Table 1]

This suggests that when viewing the screen from a farther position, the viewing angle becomes a relatively small value, so that color misregistration may be less likely to be perceived. In consideration of the situation at the time of use and the result of the first embodiment, the color display frequency Fcolor of one cycle of RGB such that the color shift is not bothersome is shown with respect to the screen vertical size and the viewing distance. Table 2] can be set. Table 2 shows the RG at each distance when the visual angular velocity was 15.0 deg./s at the 3H distance.
It is a table | surface which shows the minimum value of the color display frequency of B1 period.

[0084]

[Table 2]

Here, since the set value of the visual acuity is a close distance, it is assumed that the visual acuity does not change with the movement speed, and S = 1.0
And the field frequency F at which the image is updated is 60H
z. In the calculation of [Table 2], the expression (1)
If the result of 2) exceeds 150 Hz, equation (13)
The result by was adopted.

From the results shown in Table 2, it can be seen that the RGB color display frequency is substantially 150 Hz or less at a distance exceeding three times the screen height. Assuming that the distance to the hand is about 60 cm, a display device having an aspect ratio of 4: 3 has a screen of about 4 inches diagonally (about 6 inches in screen height).
cm) and a color display frequency of 60 Hz is sufficient,
It can be seen that a display device having a smaller screen size can display an image at a color display frequency lower than the video rate to a degree that does not cause color shift.

This is effective when an image cannot be captured at the video rate due to a problem in the apparatus, or when the field frequency is reduced and displayed by image thinning. For example, in the case where the display device having a screen vertical size of 2 cm in Table 2 can capture an image only at 10 Hz, it is sufficient to output the image at an RGB color display frequency of 15 Hz or more at the time of display. This avoids the need to output at 60 Hz and simplifies the circuit configuration.

In Table 2 above, on a screen having a screen height of about 12 cm or more, the viewer should be observed at a distance of 60 cm or more, and according to the value shown in Table 2, at least 80 Hz to 130 Hz. If the color display frequency Fcolor is set in between, a moving image can be visually recognized within a range in which a color shift is not bothersome. In the second to sixth embodiments, the motion visual angular velocity ω of the motion image is set to an appropriate value. However, these set values are arbitrarily set as is clear in the process of deriving the above equation. The same color display mechanism is effective for display devices of various standards.

Seventh Embodiment In the setting of the color display frequency described in the first to sixth embodiments, if the setting is such that the color misregistration is not a problem, it is repeated m times in one field. When color display is performed, the contour portion of the fast moving image is perceived as m multiple images, and may be felt as strong image deterioration. When the movement is relatively slow, the multiple images are connected and perceived as motion blur, so that a sense of obstruction was felt.

Here, the color display frequency Fco of one cycle of RGB is used.
lor = 160 Hz, field frequency F = 53.3 Hz
In the case of the above, using the following display sequence, the effects of the motion blur and the improvement of the interference by the multiple images were compared for a motion image having a visual angular velocity ω = 12 deg./s at a distance three times the screen height. Note that the following settings are conditions that satisfy Expression (18).

In one field period, the color display is changed from RGB | RGB | RGB to RGB = 3.
When the color is displayed twice, the color display is changed to RGB 2 as RGB | RGB | DDD.
When the color is displayed twice, the color display is set to 1 for RGB | DDD | DDD.
Here, D is a period in which no color is displayed.

In the above sequence, when comparing the motion blur caused by the visual line following of the motion image, the following relationship was obtained. The multiple images were observed as triple images, double images, and no multiple images in each sequence.

In each of the drive sequences, the color shift was not bothersome, but the multiple images in the and sequences were bothersome. I was worried about motion blur most, but not so much.
Accordingly, by using the setting method based on Expression (18), a high-quality image with less motion blur caused by the observer's line of sight following the moving image in field sequential driving and image quality disturbance due to multiple images is provided. can do.

[0094]

As described above in detail, according to the present invention, in an image display apparatus which performs color display in a time-division manner, a drive frequency condition which does not cause a color shift seen when a line of sight follows a moving image. Can provide a method for determining
It is possible to provide a high-quality display device without color shift due to such visual characteristics. In addition, it is possible to provide a method for reducing image blur due to motion blur and multiple images based on the same visual principle, and a high-quality display device in which the blur is reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a visual angular velocity when a motion image follows a line of sight with respect to a distance from a video display surface.

FIG. 2 is a motion model diagram for explaining a visible luminance distribution that can be visually recognized when a line of sight follows a moving image in a display device that performs color display in a time-division manner.

FIG. 3 is a motion model diagram for explaining a visible luminance distribution that can be visually recognized when a line of sight follows a motion image in a display device having a normal stripe pixel structure.

FIG. 4 is a model diagram illustrating a viewing angle at which colors can be independently separated and visually recognized.

FIG. 5 is a model diagram illustrating a viewing angle at which mixed colors can be visually recognized separately.

FIG. 6 is a diagram illustrating a lower limit value of a display frequency at which a color shift cannot be visually recognized for each visual acuity, according to a moving speed of an image.

FIG. 7 is a diagram showing a lower limit value of a display frequency at which a color shift cannot be visually recognized according to a visual acuity of a viewer with respect to a moving speed of each image.

FIG. 8 is a diagram showing relative visual acuity of moving object visual acuity;

FIG. 9 is a diagram for evaluating an error between Expression (1) and Expression (1 ′).

FIG. 10 is a diagram illustrating a relationship between a visual angular velocity and a visual acuity of a viewer who do not care about a color shift at a color display frequency Fcolor = 53.3 Hz.

FIG. 11 is a diagram illustrating a relationship between a visual angular velocity and a visual acuity of a viewer who do not care about a color shift at a color display frequency Fcolor = 80.0 Hz.

FIG. 12 is a diagram illustrating a relationship between a visual angle speed at which a color shift at a color display frequency Fcolor = 160 Hz is not a concern and a visual acuity of a viewer.

[Explanation of symbols]

 F Field frequency [Hz] ω Viewing speed of moving image [deg./s] S Visual power of observer watching moving image m Reciprocal of ratio of one cycle of color display in one field period C Number of display colors Fcolor One cycle Color display frequency Tdisp display period

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 5/36 510 G09G 5/36 510M H04N 9/30 H04N 9/30 9/31 9/31 B

Claims (7)

[Claims] 1. An image display apparatus that sequentially and sequentially displays display colors in a time-division manner. The reciprocal of the ratio of one cycle of the color display in one field period is m (m is a positive real number)
, The color display frequency F of one cycle based on the number of display colors C
color [Hz] is a frequency that satisfies the following equation. An image display device characterized by the above-mentioned. 2. When the color display frequency Fcolor of one cycle based on the display color number C exceeds 150 Hz, the color display frequency Fcolor is a frequency satisfying the following expression. The image display device according to claim 1, wherein: 3. A color display period in a field, where one color display frequency is Fcolor, a field frequency is F, and the number of repeated color display cycles in a field is k (k is a natural number). Tdisp is a period satisfying the following equation. The image display device according to claim 1, wherein: 4. An image display method in which display colors are sequentially and sequentially displayed in a time-division manner. The reciprocal of the ratio of one cycle of color display in one field period is m (m is a positive real number)
, The color display frequency F of one cycle based on the number of display colors C
Let color [Hz] be the frequency shown by the following equation. An image display method comprising: 5. When the color display frequency Fcolor [Hz] of one cycle based on the display color number C exceeds 150 Hz, the frequency is represented by the following equation. 5. The image display method according to claim 4, wherein: 6. A color display period in a field when a color display frequency of one cycle is Fcolor, a field frequency is F, and the number k of repeated color display in a field is k (k is a natural number). Let Tdisp be the period shown by the following equation: The image display method according to claim 4 or 5, wherein: 7. A one-period color display frequency Fcolor and a field within a field based on the visual angle velocity ω and the visual acuity S of the observer when the moving image is tracked by the user, The image display method according to any one of claims 4 to 6, wherein the number k of repeated display of periodic color display is calculated.