JP2003177719A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device in which occurrence of both shaking image degradation and moving image degradation can be suppressed. <P>SOLUTION: The device is provided with a display section which is used to conduct image display and a light emitting means which is used to emit light beams toward the display section. In the device, image display corresponding to the image signals being inputted from the outside is conducted at the display section for every frame interval by utilizing the light emission by the light emitting means. When the frame frequency is high, the image display is conducted so that the percentage of occupancy of the light emission utilization interval in the frame interval is set low. On the other hand, when the frame frequency is low, the percentage of occupancy of the light emission utilization interval in the frame interval is set high. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device for intermittent display, and more particularly to an image display device capable of reducing image deterioration caused by vibration.

[0002]

2. Description of the Related Art An image display device having a light emitting means for displaying an image by utilizing the light emitted by the light emitting means maintains the light emission used for the image display at a substantially constant luminance for one frame period. Hold type and impulse type in which the light emission is impulse type. Examples of the hold type image display device include a TFT drive type liquid crystal display device and the like. On the other hand, examples of the impulse type image display device include a CRT and the like.

Although these hold-type image display devices and pulse-type image display devices have different display characteristics, the pulse-type image display device is the hold-type image display device for displaying moving images, for example. It is said that it is more suitable than. Hereinafter, this point will be described.

When observing an image on an image display device, an observer perceives as if the image is continuous by a sensation called apparent movement. Here, apparent motion is defined as when two or more frames are replaced at very short time intervals.
It is the sense that the objects drawn in those frames are perceived as if they were actually moving.

As described above, in the hold type image display device, the light emission used for image display is kept at a substantially constant brightness for one frame period, so that the image is always displayed. . Therefore, each image is perceived more clearly than in the case of the impulse type. As a result, the apparent movement described above is disturbed, and as a result, it is perceived that the moving image display is significantly deteriorated. Hereinafter, such image deterioration is referred to as moving image deterioration.

On the other hand, in the case of an impulse type image display device, since the light emission used for image display is impulse-like as described above, the image is displayed intermittently. Therefore, since a smooth moving image display can be obtained without disturbing the apparent motion, the moving image deterioration is hardly felt.

As described above, since the impulse type image display device is more suitable for displaying moving images than the hold type image display device, it is desirable to use the impulse type image display device when moving image display is often performed. . Therefore, even a hold-type TFT drive type liquid crystal display device, which is close to an impulse type such as a field sequential color system or a blinking backlight system, which realizes intermittent display by blinking the backlight, is used. It is expected to spread in the future.

[0008]

By the way, in recent years, image display devices have been used in various fields, and their use environments are also diverse. For example, although liquid crystal display devices are used in mobile phones, car navigation systems, etc., these liquid crystal display devices are used in environments subject to various vibrations such as camera shake and shaking of vehicles.

FIG. 12 is a view showing a state of image display observed on the image display device when such image vibration is received. FIG. 12A is a hold type image display device. Conceptual diagram showing a state of the image display in FIG.
FIG. 3 is a conceptual diagram showing a state of image display on an impulse type image display device. FIG. 12 exemplifies a case where the character “A” is displayed on the display screen of the image display device. The arrow X in the figure indicates the direction of shaking when the display screen of the liquid crystal display device shakes due to vibration, and the arrow Y indicates the moving direction of the character "a" observed in that case. ing.

As shown in FIG. 12A, in the case of the hold type image display device, the shaking direction X and the moving direction Y of the observed character "A" are substantially the same. That is, it is observed that the character "A" moves in the same direction as the shaking direction X. This is similar to the movement observed when the paper on which the character “A” is written is shaken in the same direction as the direction A. In this way, the shaking direction A and the moving direction B of the observed character "A" correspond to each other, so that the observer feels little discomfort.

On the other hand, as shown in FIG. 12 (b), in the case of the impulse type image display device, the character "a" is displayed intermittently, so the direction X of shaking and the movement of the observed character "a". The direction Y is very different. That is, it is observed that the character "A" moves in a direction different from the shaking direction X. As described above, since the shaking direction X does not correspond to the moving direction B of the observed character "A", the observer perceives that the image is significantly deteriorated. Hereinafter, such image deterioration is referred to as shake image deterioration.

As described above, since the shaking image deterioration occurs,
It is preferable that the image display device used in an environment where it is subjected to vibration be of the hold type rather than the impulse type. However, as described above, in the case of the hold type image display device, there is a problem that moving image deterioration occurs.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an image display device capable of reducing both moving image deterioration and shaking image deterioration.

[0014]

Means for Solving the Problems As a result of experiments conducted by the inventors of the present invention, an image display device for displaying by dividing one frame period into several sub-frames such as the field sequential color system is shown. , It was found that the shaking image deterioration is reduced by increasing the number of subframes. From this, it was considered that the shake image deterioration can be reduced by setting the frame frequency high. Then, based on this consideration, the following experiment was conducted. Note that, hereinafter, a period in which light emission is used to display an image will be referred to as a light emission use period.

First, a swaying state is generated by periodically moving the display section of the image display device to the left and right, and the frame frequency and the ratio of the light emission utilization period in each frame period (hereinafter referred to as the light emission rate) are calculated. 100 subjects were made to observe a plurality of still images while changing. Then, the double deterioration stimulus scale method (do
uble stimulus continuous quality scale)
We asked these subjects to make subjective evaluations of the shaking image deterioration. Here, the shaking speed at which characters can be confirmed when the display is shaken is set to 25 deg / sec or more and 28 deg / sec or less.

The boundary value of the light emission rate was calculated from the result of the above-mentioned subjective evaluation. Note that, here, the boundary value when 50% of the viewers perceive that the shake image deterioration is slightly perceived but within a sufficiently permissible range is defined as an allowable limit.
The limit value was set as the limit value when 0% of the observers perceive deterioration of the shake image, but evaluated that there was no great obstacle in observing the image.

FIG. 13 is a graph showing the allowable limit and the patience limit calculated from the result of the subjective evaluation. The horizontal axis of this graph shows the frame frequency and the vertical axis shows the light emission rate. As shown in FIG. 13, paying attention to each boundary value, it can be seen that the frame frequency and the light emission rate have a negative proportional relationship. Therefore, these boundary values have the linear form y = x
It can be represented by xa + b. Here, x is the frame frequency f, y is the light emission rate w1, and a is a negative constant,
When b is a positive constant, the above-mentioned boundary value is w1 = f × a
It can be represented as + b. When the tolerance limit and the patience limit shown in FIG. 13 are applied to w1 = f × a + b, they are expressed as follows.

Endurance limit w1 = −1.13 × 10 ⁻² × f + 1.46 Allowable limit w1 = −4.5 × 10 ⁻³ × f + 1.19 Therefore, w1> −1.13 × 10 ⁻² × f + 1.19 46
In the case of, it is possible to obtain an image above the patience limit, and in the case of w1> −4.5 × 10 ⁻³ × f + 1.19, an image above the tolerance limit can be obtained.

Based on the above experimental results, the present inventors invented the following image display device.

An image display device according to the present invention comprises a display section for displaying an image and a light emitting means for emitting light to the display section, and displays an image corresponding to an image signal input from the outside. In the image display device which performs light emission by the light emitting means on the display unit for each frame period,
The display unit and / or the light emitting means are controlled so that the light emission utilization period in which the light emission is used in the display unit occupies low and high in each frame period according to the high and low frame frequencies. It is characterized by comprising a control means for controlling (claim 1).

As described above, it was found from the result of subjective evaluation that the frame frequency and the light emission rate have a negative proportional relationship. Therefore, by lowering the light emission rate when the frame frequency is high and increasing the light emission rate when the frame frequency is low, it is possible to suppress the shake image deterioration.

Further, in the image display device according to the present invention, the control means may control the display portion and / or the light emitting means so as to satisfy the expression w1> f × a + b (claim). 2). This allows the frame frequency and the light emission rate to maintain a negative proportional relationship,
It is possible to suppress shake image deterioration.

In the image display device according to the present invention, the a is in the range of -1.13 × 10 ^-2 ± 0.5 × 10 ^-2 , and the b is in the range of 1.46 ± 0.05. It may be inside (Claim 3). As a result, it is possible to obtain an image that exceeds the patience limit described above.

In the image display device according to the present invention, the a is in the range of −4.5 × 10 ⁻³ ± 0.2 × 10 ⁻³ , and the b is in the range of 1.19 ± 0.05. It may be inside (Claim 4). As a result, it is possible to obtain an image that exceeds the above-mentioned allowable limit.

In the image display device according to the present invention, the f may be set to 130 Hz or less (claim 5), and the f may be set to 270 Hz or less (claim 6).

By the way, the inventors of the present invention conducted the following experiment in order to obtain a subjective evaluation regarding deterioration of a moving image.

First, the image displayed on the display section of the image display device was moved left and right at a constant speed, and 100 subjects were observed while changing the light emission rate and the moving speed. Then, based on the double deterioration stimulus scale method, which is a well-known subjective evaluation method, these subjects were made to make a subjective evaluation of the moving image deterioration. Here, the frame frequency of the moving image display is 5
It was performed at 5 Hz or more and 80 Hz or less.

The boundary value of the luminescence rate was calculated from the result of the above-mentioned subjective evaluation. It should be noted that, here, the boundary value when 50% of the observers do not perceive the moving image deterioration at all is set as a detection limit, and 50% of the observers perceive the moving image deterioration slightly, but within a sufficiently permissible range. The boundary value in the case of being evaluated as is set as the allowable limit, and the boundary value in the case of being evaluated that 50% of observers perceive the deterioration of the moving image but not a big obstacle in observing the image is set as the permissible limit.

As a result of such a subjective evaluation, it was found that the lower the light emission rate, the less perceptible the deterioration of the moving image. The detection limit, the allowable limit, and the patience limit are 0.
It was 5 ± 0.05, 0.7 ± 0.05, 0.9 ± 0.05.

Therefore, in the image display device according to the present invention, the w1 may be 0.9 or less (claim 7) and the w1 may be 0.7 or less (claim 8). Further, the w1 may be 0.5 or less (claim 9). This makes it possible to suppress not only the shaking image deterioration but also the moving image deterioration.

In the image display device according to the present invention, the light emission utilization period may include a plurality of light emission pulse periods (claim 10). Then, in this case, each frame period is divided into a plurality of subframe periods, each of the subframe periods is configured to include one of the light emission pulse period, the control means,
The proportion of the light emitting pulse period in each subframe period is w2, the frame frequency is f, the negative constant is a, the positive constant is b, and the number of the subframe periods in each frame period is n. Then, the equation w2> f × n ×
You may make it control the said display part and / or said light emission means so that a + b may be satisfied (Claim 11). Accordingly, it is possible to realize an image display device capable of suppressing shake image deterioration by, for example, a blinking backlight method in which a display is performed by generating a light emission pulse in each subframe period.

Further, in the image display device according to the present invention, the display section may be configured by using a liquid crystal display element (claim 12). As a result, it is possible to realize a liquid crystal display device capable of suppressing shake image deterioration.

Further, in the image display device according to the present invention, the liquid crystal display element may include liquid crystal molecules that are in bend alignment when the image is displayed (claim). 13). As a result, OCB (Opt
It is possible to realize a liquid crystal display device of a ically compensated birefringence mode that can suppress shake image deterioration.

In the image display device according to the present invention, the light emitting means may be a backlight provided below the display section (claim 14). This allows
A liquid crystal display device that emits light with a backlight,
It is possible to realize a device capable of suppressing shake image deterioration.

In the image display device according to the present invention, the light emitting means has a light source for emitting red, green, and blue light, respectively, and the control means has the light source within one frame period. The light emitting means may be controlled so that each color light is emitted in a time division manner (claim 15). Accordingly, it is possible to realize a liquid crystal display device capable of suppressing shake image deterioration by the field sequential color system.

Further, as described above, the lower the light emission rate is, the less perceptible the moving image deterioration is. Therefore, it is desirable to reduce the light emission rate in order to suppress the moving image deterioration. Therefore, the image display apparatus according to the present invention includes a display unit for displaying an image and a light emitting unit for emitting light to the display unit, and the image display corresponding to an image signal input from the outside emits light. In the image display device that performs light emission by the means on the display unit for each frame period,
A first light emission pattern in which the light emission utilization period of utilizing the light emission in the display section occupies low or high in each frame period according to the high or low frame frequency; or
A control means for controlling the display unit and / or the light emitting means based on a second light emitting pattern that reduces the ratio as compared with the light emitting pattern is provided.
6).

With such a structure, light emission can be performed according to either the first pattern or the second pattern. Therefore, when the influence of the shake image deterioration is large, light is emitted by the first light emission pattern, and when the influence of the moving image deterioration is large, light is emitted by the second light emission pattern. This makes it possible to maintain good image display.

Further, the image display device according to the present invention further comprises pattern switching instruction means for instructing the control means to switch the light emission pattern, and the control means responds to the instruction from the pattern switching instruction means. The display unit and / or the light emitting means may be controlled based on one light emission pattern or the second light emission pattern (claim 17). By thus providing the pattern switching instruction means, it becomes possible to easily switch between the first pattern and the second pattern.

In the image display device according to the present invention, the pattern switching instructing means may instruct the switching according to the image signal (claim 1).
8). Thereby, for example, when the image signal input from the outside is to display a still image, the first light emission pattern is instructed to emit light, and when it is to display a moving image, the second image is displayed. By instructing to emit light according to the light emission pattern, it is possible to maintain good image display.

Further, when characters are displayed on the display unit, the influence of shake image deterioration is significant. Therefore, in the image display device according to the present invention, when the pattern switching instructing means displays an image in which the image signal includes characters, the display unit and / or the display unit based on the first light emission pattern. The control means may be instructed to control the light emitting means (claim 19). This makes it possible to suppress shake image deterioration when an image including characters is displayed.

Further, in the image display device according to the present invention, when the pattern switching instruction means is for displaying a moving image, the display unit and / or the display unit based on the second light emission pattern. The control means may be instructed to control the light emitting means (claim 20). Accordingly, when a moving image is displayed on the display unit, it is possible to emit light according to the second light emission pattern that can suppress deterioration of the moving image.

Further, in the image display device according to the present invention, the ratio of the light emission utilization period in each frame period in the second light emission pattern may be 0.9 or less (claim 21), and 0.7 or less. (Claim 2
2). The ratio may be 0.5 or less (claim 23).

Further, the image display device according to the present invention further comprises vibration sensing means for sensing the vibration, and the pattern switching instructing means directs the switching based on the result of the sensing by the vibration sensing means. (Claim 24). Accordingly, for example, when the vibration sensing unit senses a predetermined degree of vibration, it is possible to perform light emission according to the first light emission pattern that suppresses shake image deterioration.

Further, in the image display device according to the present invention, when the pattern switching instructing means senses a shake of 20 deg / sec or more in one direction, the pattern switching instructing means is operated based on the first light emission pattern. The control means may be instructed to control the light emitting means (claim 25). As a result, it is possible to perform light emission according to the first light emission pattern that can suppress deterioration of the shake image when a relatively strong shake occurs.

Further, in the image display device according to the present invention, when the pattern switching instructing means senses a shake of 20 deg / sec or less in one direction, the pattern switching instructing means is operated based on the second light emission pattern. The control means may be instructed to control the light emitting means (claim 26). As a result, it is possible to perform light emission according to the second light emission pattern that can suppress deterioration of a moving image when a relatively weak shake occurs.

[0046]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following, a case where the image display device of the present invention is a liquid crystal display device that displays an image using a liquid crystal display element will be exemplified.

(Embodiment 1) FIG. 1 is a sectional view schematically showing an image display device according to Embodiment 1 of the present invention. In the drawings, the X direction is defined as the upward direction of the image display device 1 for convenience of description.

As shown in FIG. 1, the image display device 1 is provided with a liquid crystal display element 10, and the liquid crystal display element 10 is constructed by laminating polarizing plates 11 on both sides of a liquid crystal cell 12. As shown in FIG. 2, the liquid crystal display element 10 includes two substrates, that is, an upper substrate 27 and a lower substrate 2.
8 and these upper substrate 27 and lower substrate 2
8 are arranged to face each other through a spacer (not shown). Further, a liquid crystal layer 29 is arranged in a gap formed between the upper substrate 27 and the lower substrate 28, and liquid crystal molecules 26 are injected into the liquid crystal layer 29.

The liquid crystal display element 10 thus constructed
Is applied to change the alignment state of the liquid crystal molecules 26 from splay alignment (state shown in FIG. 2A) to bend alignment (FIG. 2).
The state shown in (b) is changed to an image by this bend orientation. That is, the liquid crystal display element 10 is called an OCB mode. However, it goes without saying that the present invention is not limited to the OCB mode and can be applied to other modes such as a TN (Twisted-Nematic) mode.

A backlight 20 is arranged below the liquid crystal display element 10 described above. Such a backlight 20
Is a light guide plate 23 made of a transparent rectangular synthetic resin plate, and an arc tube 21 which is a light emitter arranged near one end face 23a of the light guide plate 23 along the end face 23a and substantially parallel to the end face 23a. And a reflector 22 that covers the arc tube 21 over substantially the entire length thereof, and a reflector plate 2 disposed below the light guide plate 23.
4 and a diffusion sheet 25 provided on the upper surface of the light guide plate 23.

The backlight 20 constructed as described above
Then, the light emitted from the light emitting tube 21 enters the light guide plate 23 through the end face 23a. The incident light is multiple-scattered inside the light guide plate 23 and emitted from the entire upper surface thereof. At this time, light that leaks below the light guide plate 23 and enters the reflection plate 24 is reflected by the reflection plate 24 and returned to the inside of the light guide plate 23.
The light emitted from the light guide plate 23 is diffused by the diffusion sheet 25, and the diffused light enters the liquid crystal display element 10. As a result, the entire liquid crystal display element 10 is uniformly irradiated with light.

FIG. 3 is a block diagram showing the configuration of the image display device 1 according to the first embodiment of the present invention. Referring also to FIGS. 1 and 2, the liquid crystal display element 10 is of a well-known TFT (Thin Film Transistor) type,
A counter substrate (not shown) having a common electrode (not shown) formed on its inner surface and a TFT substrate (not shown) having pixel electrodes 39, scanning lines 31, signal lines 32 and switching elements 33 formed on its inner surface. And are arranged so as to face each other with the liquid crystal layer 29 interposed therebetween. In this TFT substrate, scanning lines 31 and signal lines 32 are arranged in a matrix, and a pixel electrode 39 and a switching element 33 are formed for each pixel partitioned by the scanning lines 31 and signal lines 32. . The scanning line 31 and the signal line 32 of the liquid crystal display element 10 are driven by the gate driver 34 and the source driver 35, respectively, and the gate driver 34 and the source driver 35 are controlled by the control circuit 36. The operation of the backlight 20 is controlled by the backlight control circuit 37.

In the image display device 1 configured as described above, the control circuit 36 responds to the image signal 38 input from the outside in order to realize the image display with the light emission rate determined as described later. Then, control signals are output to the gate driver 34, the source driver 35, and the backlight control circuit 37, respectively. As a result, the gate driver 34 applies the scanning signal voltage to the scanning line 31 to sequentially turn on the switching element 33 of each pixel, while the source driver 35 applies the pixel signal voltage to each pixel through the signal line 32 at the timing. The pixel electrodes 39 are sequentially applied. Here, the pixel signal voltage is a voltage corresponding to the pixel signal written to each pixel according to the image signal 38. As a result, the liquid crystal molecules are modulated and the transmittance of the light emitted from the backlight 20 changes. As a result, the image corresponding to the image signal 38 is displayed with the above-described light emission rate.

Next, the operation of the image display device 1 of this embodiment will be described.

FIG. 4 is a timing chart showing an example of display control of the image display device according to the first embodiment of the present invention. FIG. 4A shows a change in luminance in the liquid crystal display element 10, and FIG. The change in the signal level of the pixel signal in the element 10 is shown. In FIG. 4, T1
Indicates one frame period, and each one frame period T1
Is composed of a light emission utilization period T2 and a black display period T3. Here, the black display period T3 refers to a period during which black display is performed by writing a pixel signal whose signal level is the black display signal level SB to the pixel.

Since black display is performed during the black display period T3, the luminance is low as shown in FIG.
On the other hand, in the light emission use period T2, the brightness changes according to the signal level of the pixel signal.

By providing the black display period T3 in this way, there is an advantage that the image is cut off well. Therefore, it has been conventionally proposed to provide such a black display period T3. However, in the present embodiment,
In addition to improving the sharpness of the image, a black display period T3 is provided to set the light emission rate to a predetermined value. That is, the length of the light emission use period T2 is changed by adjusting the length of the black display period T3. Then, as a result, the light emission rate, which is the ratio occupied by the light emission use period T2 in one frame period T1, is set to a value that satisfies the above-described w1> f × a + b (Equation 1). Note that w1 in this equation is the above-described light emission rate, that is, the ratio occupied by the light emission utilization period T2 in each frame period T1, f is a frame frequency, a is a negative constant, and b is a positive constant. There is.

FIG. 5 shows an image according to the first embodiment of the present invention.
One of the relationships between the frame frequency and the light emission rate in a display device
It is a graph which shows an example. In FIG. 5, A is the above
Permission obtained from the result of subjective evaluation of shake image degradation
Expression w1 = −4.5 × 10^-3Xf + 1.19
Shows. Here, w1 is the above-mentioned light emission rate, and f is the flux.
The ram frequencies are shown respectively. As mentioned above,
w1> -4.5 × 10 ^-3If xf + 1.19,
Images exceeding the allowable limit can be obtained.

From the result of the subjective evaluation of the above-mentioned moving image deterioration, the case where the light emission rate is 0.5 or less is the most preferable, and the case where the light emission rate is 0.7 or less and 0.9 or less is next. It turns out to be preferable.

Therefore, in the present embodiment, in order to suppress both the shake image deterioration and the moving image deterioration, both range a1, range a1 + a2, or range a1 + a2 + a shown in FIG.
The light emission rate is determined so as to fall within any of the ranges of 3. Here, in consideration of the suppression of the deterioration of the moving image, the range a1, the range a1 + a2, and the range a1 + a2 + a3 are preferable in this order. However, since the light emission rate decreases in this order, the brightness decreases accordingly. Therefore, when importance is attached to the screen brightness, the range a1 + a2 + a3, the range a1
+ A2 and range a1 are preferred in this order. Therefore, the range in which the light emission rate is determined depends on the performance, application, use environment, etc. of the image display device. It should be noted that an observer may be provided with a means capable of selecting these ranges so that the observer can set them according to his or her preference.

Here, a in Expression 1 is -4.5.
Although a × 10 ^-3, a possible value is not limited ^{thereto, -4.5 × 10 -3 ± 0.2 ×} 10 -3
Within the range of. Similarly, b is set to 1.19, but the value that b can take is not limited to this, and may be within the range of 1.19 ± 0.05.

FIG. 6 is a graph showing another example of the relationship between the frame frequency and the light emission rate in the image display device according to the first embodiment of the present invention. In FIG. 6, B is an expression w1 = −1.13 × 10 ⁻² × f + 1.4 representing a patience limit obtained from the result of the subjective evaluation of the above-described shake image deterioration.
6 is shown.

From the result of subjective evaluation of moving image deterioration, the light emission rate w1 is 0.5 or less, 0.7 or less, 0.9 or less.
It is as described above that the following order is preferable.

Therefore, in the present embodiment, in order to suppress both the shaking image deterioration and the moving image deterioration, FIG.
Range b1, range b1 + b2, or range b1 + b2 shown in
The light emission rate may be set so as to fall within any of + b3.

The range a1 and range a1 + shown in FIG.
a2, range a1 + a2 + a3, or range b shown in FIG.
Which of the range 1, the range b1 + b2, and the range b1 + b2 + b3 is adopted depends on the performance of the image display device and the like as in the case described above. For example, when the frame frequency is relatively high (eg, higher than 130 Hz and lower than 270 Hz), range a1, range a1 + a2, or range a1 + a.
If either of 2 + a3 has a relatively low frame frequency (for example, 130 Hz or less), range b1 and range b
Either 1 + b2 or the range b1 + b2 + b3 can be adopted.

Here, a in Expression 1 is -1.1.
Although it is set to 3 × 10 ⁻² , the value that a can take is not limited to this, and −1.13 × 10 ⁻² ± 0.5 × 1
It may be in the range of 0 ^-2 . Similarly, b is set to 1.46, but the value that b can take is not limited to this, and may be within the range of 1.46 ± 0.05.

(Second Embodiment) In the image display device according to the first embodiment, light emission is continued during the light emission utilization period T2 as shown in FIG. On the other hand, in the image display device according to the second embodiment, the light emission use period is configured to include a plurality of light emission pulse periods, and light emission is performed intermittently.

As an image display device which emits light intermittently in this way, there are, for example, a blinking backlight system and a field sequential color system. Therefore, the image display device according to the present embodiment is based on these methods.

Since the configuration of the blinking backlight type image display device is the same as that of the first embodiment, the description thereof is omitted. The field-sequential color type image display device has a light source such as a light emitting diode and an electroluminescent light emitting element whose backlight emits light of each of the three primary colors of light of red, green and blue. The other configuration is similar to that of the first embodiment, and therefore its explanation is omitted.

The operation of the image display device according to this embodiment will be described below.

FIG. 7 is a conceptual diagram showing an example of the light emission utilization period in the image display device according to the second embodiment of the present invention. In FIG. 7, P1 indicates a light emission pulse period in which light is emitted instantaneously, and this light emission pulse period P1 coincides with the light emission use period T2. Ie 1
The light emission utilization period T2 in the sub-frame period T1 is composed of a plurality of light emission pulse periods P1.

Further, T4 indicates a subframe period obtained by dividing one subframe period T1 at equal intervals, and each subframe period T4 is configured to include one light emission pulse period P1. Note that here, one frame period T1 is 3
Although it is composed of one sub-frame period T4, it goes without saying that the number of sub-frame periods T4 is not limited to this.

The frame frequency of each sub-frame period T4 described above is 3 of the frame frequency of one frame period T1.
Doubled. That is, when the number of subframe periods T4 is n, the frame frequency of each subframe period T4 is n times the frame frequency of one frame period T1. Therefore, when the above-described Equation 1 is applied to the present embodiment, the ratio of the light emission pulse period in each subframe period T4 is the light emission rate w2, the frame frequency is f, the negative constant is a, and the positive constant is. Where b is and the number of subframe periods T4 is n, w2> f × n × a + b (Equation 2) can be obtained. Therefore, in the present embodiment, the light emission rate w2 is set to a value that satisfies the expression 2. This makes it possible to suppress the shake image deterioration.

Further, similarly to the case of the first embodiment, by suppressing the light emission rate w2 to be 0.5 or less, 0.7 or less, or 0.9 or less, the suppression of the deterioration of the moving image is also realized. be able to.

FIG. 8 is a conceptual diagram showing another example of the light emission utilization period in the image display device according to the second embodiment of the present invention. In FIG. 8, P2 indicates the light emission pulse interval which is the interval between the respective light emission pulse periods P1.

In the example described above with reference to FIG. 7, it is assumed that each light emission pulse period P1 and the light emission use period T2 coincide with each other. However, since the light emission pulse is instantaneous, it is possible to regard the light emission use period T2 from the first light emission pulse to the last light emission pulse among the plurality of light emission pulses in each frame period T1. Therefore, in FIG. 8, the light emission use period T2 is from the start of the first light emission pulse period P1 to the end of the last light emission pulse period P1 in each frame period T1.

The present inventors have found that these light emission pulse periods P
In order to confirm the influence of 1 and the light emission pulse interval P2 on the shake image deterioration, the following subjective evaluation was performed. First, a shaking state is generated by periodically moving the display unit included in the image display device to the left and right, and a plurality of still images are observed by 100 subjects while changing the light emission pulse period P1 and the light emission pulse interval P2. It was Then, based on the above-mentioned double deterioration stimulus scale method, these subjects were made to make a subjective evaluation of shaking image deterioration.

As a result of such subjective evaluation, the light emission pulse period P
It was found that when 1 is set to a constant length, the subjective value becomes high by making the light emission pulse interval P2 long, that is, it becomes difficult to perceive the shake image deterioration. For example, when the frame frequency is 60 Hz, the number of light emission pulse periods P1 is 3, and each light emission pulse period P1 is 1 millisecond,
The subjective value was higher when the light emission pulse interval P2 was 3 milliseconds than when it was 1 millisecond. Therefore, by making the light emission pulse interval P2 relatively long, it is possible to realize an image display device with less shaking image deterioration.

(Third Embodiment) The image display device according to the third embodiment can switch a plurality of light emission patterns.

FIG. 9 is a block diagram showing the structure of the image display device according to the third embodiment of the present invention. As shown in FIG. 9, the image display device according to the present embodiment includes a switching instruction unit 50 for instructing switching between a first light emission pattern and a second light emission pattern, which will be described later. The switching instruction section 50 is connected to the control circuit 36.

When the control circuit 36 receives the switching instruction signal 51 output from the switching instruction section 50, it changes from the first light emitting pattern to the second light emitting pattern or from the second light emitting pattern to the first light emitting pattern. In order to perform switching, control signals are output to the gate driver 34, the source driver 35, and the backlight control circuit 37, respectively. The other configurations of the image display device according to the present embodiment are the same as those in the first embodiment, and therefore, the same reference numerals are given and the description thereof is omitted.

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

FIG. 10 is a timing chart showing an example of the light emission pattern in the image display device according to the third embodiment of the present invention, where (a) shows the first light emission pattern.
(B) has each shown the 2nd light emission pattern. The light emission rates of these first and second light emission patterns are set in the same manner as in the case of the first embodiment. That is, it is determined so as to be within each range shown in FIGS. Therefore, it is possible to suppress the shake image deterioration and the moving image deterioration regardless of which light emission pattern is used to display the image.

As shown in FIG. 10, the length of one frame period T1 is the same in the first light emitting pattern and the second light emitting pattern. On the other hand, the light emission use period T2 in the first light emission pattern is equal to the light emission use period T2 in the second light emission pattern.
Is longer than. Therefore, each frame period T
The light emission rate which is the ratio of the light emission utilization period T2 in 1 is
The second light emission pattern is lower than the first light emission pattern.

As described above, the lower the light emission rate, the more difficult it is for the observer to perceive the deterioration of the moving image. Therefore, the fact that the light emission rate of the second light emission pattern is lower than the light emission rate of the first light emission pattern in this way means that the second light emission pattern has an effect of suppressing deterioration of moving images more than the first light emission pattern. It will be expensive.

On the other hand, the higher the light emission rate, the closer to the hold type image display device, so that it becomes difficult to perceive the deterioration of the shake image. Therefore, the first light emission pattern is more effective than the second light emission pattern in suppressing fluctuation image deterioration.

As described above, it is preferable to display the image by the first light emission pattern when the image is greatly affected by the shake image deterioration, that is, when the hand shake is frequently generated. Further, when the influence of the moving image deterioration is large, that is, when the moving image is displayed a lot, it is preferable to display the image by the second light emission pattern.

Therefore, in the image display device according to the present embodiment, when the image display is performed by the first light emission pattern, the influence of the moving image deterioration becomes large,
Alternatively, when an image is being displayed by the second light emission pattern and the influence of the shake image deterioration is large, the observer uses the switching instruction section 50 to instruct the control circuit 36 to switch the light emission pattern. . This makes it possible to maintain good image display.

Further, in order to further enhance the effect of suppressing the deterioration of the moving image, the light emission rate may be set to 0.5 or less, 0.7 or less, or 0.9 or less in the second light emission pattern. .

As described above, the observer selects the switching instruction section 50.
It is also possible to automatically give this instruction instead of giving an instruction to the control circuit 36 by using. For example, such a structure that the image signal 38 input from the outside is not directly input to the control circuit 36 but is input via the switching instructing unit 50, such an automatic switching instruction can be performed. Like That is, the switching instruction unit 50 determines whether the image signal 38 is for displaying a still image or a moving image, and the switching instruction unit 50 displays a still image as a result of the determination. The control circuit 36 is instructed to perform image display by the first light emission pattern in some cases, or by the second light emission pattern in the case of displaying moving images. This makes it possible to automatically maintain good image display.

As described above, when an image including characters is displayed, the influence of the shake image deterioration is significant. Therefore, the switching instruction unit 50 may instruct the control circuit 36 to display an image by the first light emission pattern when it is determined that the image signal 38 is for displaying an image including characters. .

(Embodiment 4) The image display apparatus according to Embodiment 4 is capable of automatically detecting occurrence of shake image deterioration by means of vibration sensing means for sensing vibration.

FIG. 11 is a block diagram showing the structure of the image display device according to the fourth embodiment of the present invention. As shown in FIG. 11, the image display device according to the present embodiment includes a vibration sensor 60 such as an angle sensor that functions as a vibration sensing unit. The vibration sensor 60 is connected to the switching instruction unit 50 described above. ing.

The vibration sensor 60 is provided in the image display device main body or the liquid crystal display element 10 when external vibration is applied.
If there is sway, measure the amount of sway. Then, it is determined whether or not the measured shake amount is a value equal to or more than a predetermined threshold value, and if it is determined to be a value equal to or more than the threshold value, the image is displayed by the above-described first light emission pattern. To the switching instruction unit 50. On the other hand, when it is determined that the value is smaller than the threshold value, the switching instructing unit 50 causes the image display by the second light emission pattern described above.
Instruct.

Upon receiving the instruction from the vibration sensor 60, the switching instruction section 50 outputs the switching instruction signal 51 to the control circuit 36 as in the case of the third embodiment. As a result, when the shake amount is relatively large, the image is displayed by the first light emission pattern, and when the shake amount is relatively small, the second light emission pattern is displayed.
An image is displayed by the light emission pattern. Therefore, it is possible to maintain good image display.

By the way, the present inventors conducted the following subjective evaluation in order to confirm the influence of the above-mentioned shake amount on the shake image deterioration. First, a shaking state was generated by periodically moving the image display device main body to the left and right, and a plurality of still images were observed by 100 subjects while changing the shaking amount. Then, based on the above-mentioned double deterioration stimulus scale method, these subjects were made to make a subjective evaluation of shaking image deterioration.

As a result of such subjective evaluation, the shaking amount is 20 deg /
It was found that perturbation image deterioration is perceived when it is more than sec. Therefore, by setting this 20 deg / sec to the above-mentioned threshold value, when the shake amount is 20 deg / sec or more, the image display by the first light emission pattern is performed, and when it is less than 20 deg / sec, the second display is performed. It is preferable to display an image by a light emission pattern. As a result, it is possible to suppress the shake image deterioration when the influence of the shake image deterioration is large.

In the above-described embodiments, the case where the liquid crystal display device is used as the image display device of the present invention is illustrated, but the present invention is not limited to the liquid crystal display device, and for example, a CRT or It is also applicable to other image display devices such as plasma displays. Further, the image display device of the present invention is suitable for a viewfinder or the like of a mobile phone, a video camera, a digital camera, or the like, which is easily affected by shake image deterioration. In addition, cars, trains, ships,
It is also suitable for a television receiver or monitor installed in a vehicle such as an aircraft.

[0099]

As described in detail above, according to the present invention,
Even when the shake image is deteriorated by external vibration or the moving image is deteriorated by displaying the moving image, both the shake image deterioration and the moving image deterioration can be suppressed.

Further, the present invention has excellent effects such that good image display can be maintained by appropriately switching a plurality of light emission patterns.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an image display device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing an alignment state of liquid crystal molecules.

FIG. 3 is a block diagram showing a configuration of an image display device 1 according to the first embodiment of the present invention.

FIG. 4 is a timing chart showing an example of display control of the image display device according to the first embodiment of the present invention, (a)
Shows a change in luminance in a liquid crystal display element included in the image display device, and (b) similarly shows a change in signal level of a pixel signal in the liquid crystal display element.

FIG. 5 is a graph showing an example of a relationship between a frame frequency and a light emission rate in the image display device according to the first embodiment of the present invention.

FIG. 6 is a graph showing another example of the relationship between the frame frequency and the light emission rate in the image display device according to the first embodiment of the present invention.

FIG. 7 is a conceptual diagram showing an example of a light emission utilization period in the image display device according to the second embodiment of the present invention.

FIG. 8 is a conceptual diagram showing another example of a light emission utilization period in the image display device according to the second embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of an image display device according to a third embodiment of the present invention.

FIG. 10 is a timing chart showing an example of a light emission pattern in the image display device according to the third embodiment of the present invention, where (a) shows a first light emission pattern and (b) shows a second light emission pattern. There is.

FIG. 11 is a block diagram showing a configuration of an image display device according to a fourth embodiment of the present invention.

FIG. 12 is a diagram showing a state of image display observed on the image display device subjected to vibration, and (a) is a conceptual diagram showing a state of the image display on the hold type image display device;
(B) is a conceptual diagram showing a state of the image display in an impulse type image display device.

FIG. 13 is a graph showing an allowable limit and a patience limit calculated from the results of subjective evaluation.

[Explanation of symbols]

1 Image display device 10 Liquid crystal display element 11 Polarizer 12 Liquid crystal cell 20 backlight 21 arc tube 22 reflector 23 Light guide plate 24 Reflector 25 diffusion sheet 26 Liquid crystal molecules 27 Upper substrate 28 Lower substrate 29 Liquid crystal layer 31 scan lines 32 signal lines 33 switching elements 34 Gate driver 35 Source Driver 36 Control circuit 37 Backlight control circuit 38 image signal 39 pixel electrodes 50 Switching instruction section 60 Vibration sensor 51 Switching instruction signal P1 light emission pulse period P2 light emission pulse interval T1 frame period T2 light emission usage period T3 Black display period

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 641 G09G 3/20 641E 641R 642 642Z 660 660V 3/34 3/34 J (72) Inventor Hirofumi Yamakita 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 2H090 KA07 MA00 2H091 FA44Z FA45Z GA06 GA11 LA02 2H093 NA65 NC43 NC44 ND10 5C006 AA14 AA22 AF44 AF45 AF54 BB16 BB29 GA10 BF38 GA02 BF38 GA02 BF38 CC03 DD30 FF11 JJ02 JJ04 JJ05 JJ06 KK23 KK47

Claims (26)

[Claims] 1. A display unit for displaying an image and a light emitting unit for emitting light to the display unit, wherein an image display corresponding to an image signal input from the outside is made by using the light emission by the light emitting unit. In the image display device that performs the display unit for each frame period, the proportion of the light emission utilization period in which the light emission is used in the display unit is reduced in each frame period according to the high and low frame frequencies. An image display device comprising a control means for controlling the display section and / or the light emitting means so as to be high. 2. The control means sets the ratio to w1,
The display unit and / or the light emitting means are controlled so as to satisfy the following equation when the frame frequency is f, the negative constant is a, and the positive constant is b.
The image display device according to. w1> f × a + b 3. The value a is −1.13 × 10 ⁻² ± 0.5 ×
The image display device according to claim 2, wherein the image display device is in the range of 10 ⁻² , and b is in the range of 1.46 ± 0.05. 4. The value a is −4.5 × 10 ⁻³ ± 0.2 × 1.
The image display device according to claim 2, wherein the image display device is in the range of 0 ⁻³ , and b is in the range of 1.19 ± 0.05. 5. The f is 130 Hz or less.
The image display device according to. 6. The f is 270 Hz or less.
The image display device according to. 7. The image display device according to claim 2, wherein the w1 is 0.9 or less. 8. The image display device according to claim 2, wherein the w1 is 0.7 or less. 9. The image display device according to claim 2, wherein the w1 is 0.5 or less. 10. The image display device according to claim 1, wherein the light emission use period includes a plurality of light emission pulse periods. 11. Each frame period is divided into a plurality of sub-frame periods, each of the sub-frame periods is configured to include one light emission pulse period, and the control means is arranged within each sub-frame period. When the ratio of the light emission pulse period is w2, the frame frequency is f, the negative constant is a, the positive constant is b, and the number of the subframe periods in each frame period is n, 11. The image display device according to claim 10, wherein the display unit and / or the light emitting unit is controlled so as to satisfy the expression of. w2> f × n × a + b 12. The image display device according to claim 1, wherein the display section is configured by using a liquid crystal display element. 13. The image display device according to claim 12, wherein the liquid crystal display element has liquid crystal molecules that are in a bend orientation when the image is displayed. 14. The display device according to claim 12, wherein the light emitting unit is a backlight provided below the display unit. 15. The light emitting means includes a light source that emits red, green, and blue color lights, respectively, and the control means causes the light source to time-division each color light within one frame period. The image display device according to claim 14, wherein the light emitting means is controlled so as to emit light. 16. A display section for displaying an image and a light emitting means for emitting light to the display section are provided, and image display corresponding to an image signal inputted from the outside is performed by utilizing the light emission by the light emitting means. In the image display device that performs the light emission on the display unit for each frame period, the proportion of the light emission use period that uses the light emission on the display unit in each frame period decreases according to the high and low frame frequencies. , High first
An image display device, comprising: a control unit that controls the display unit and / or the light emitting unit based on a light emitting pattern or a second light emitting pattern that reduces the ratio in comparison with the first light emitting pattern. 17. A pattern switching instructing means for instructing the control means to switch the light emitting pattern, wherein the control means is responsive to the instruction from the pattern switching instructing means for the first light emitting pattern or the second light emitting pattern. The image display device according to claim 16, wherein the image display device and / or the light emitting means are controlled based on the above. 18. The image display device according to claim 17, wherein the pattern switching instructing means instructs the switching in response to the image signal. 19. The pattern switching instruction means, when the image signal is for displaying an image including characters, based on the first light emission pattern, the display unit and / or
The image display device according to claim 18, which instructs the control means to control the light emitting means. 20. The pattern switching instruction means, when the image signal is for displaying a moving image, the second
The image display device according to claim 18, which instructs the control unit to control the display unit and / or the light emitting unit based on a light emitting pattern. 21. The image display device according to claim 16, wherein a ratio occupied by the light emission utilization period in each frame period in the second light emission pattern is 0.9 or less. 22. The image display device according to claim 16, wherein a ratio occupied by the light emission utilization period in each frame period in the second light emission pattern is 0.7 or less. 23. The image display device according to claim 16, wherein a ratio occupied by the light emission utilization period within each frame period in the second light emission pattern is 0.5 or less. 24. The image display according to claim 16, further comprising vibration sensing means for sensing vibration, wherein the pattern switching instructing means directs the switching based on a result of sensing by the vibration sensing means. apparatus. 25. The pattern switching instructing means, based on the first light emission pattern, of the display unit and / or the light emitting means when the vibration sensing means senses a shake of 20 deg / sec or more in one direction. The image display device according to claim 23, which instructs the control means to perform control. 26. The pattern switching instructing means of the display unit and / or the light emitting means based on the second light emitting pattern when the vibration sensing means senses a shake of 20 deg / sec or less in one direction. The image display device according to claim 23, which instructs the control means to perform control.