JPH06102484A - Meothod and device for displaying image using spatial optical modulation element - Google Patents

Abstract

PURPOSE:To provide a method and a device for displaying an image displaying the bright and high quality image with a wide dynamic range and with an excellent gradation display characteristic even in the case of a dark image by using a spatial optical modulation element. CONSTITUTION:A peak level Vp is detected at every fixed period of a video signal Vin supplied from the outside. A gain Gs=Vp/Vo is calculated from the detected peak level Vp. However, a reference peak level Vo is defined as the standard peak level of the supplied video signal. After the gain Gs is calculated, the video signal level is modulated as Vc=Vin/Gs. The modulated video signal Vc is converted to a drive signal, and the spatial optical modulation element is driven by it. Simultaneously, a light output level Lout in a light emission part is made Lout=GsXLo by using the gain Gs. Where, Lo is a reference light output level in the light emission part. By repeating mentioned processing at every fixed period, the bright image with an excellent gradation characteristic and a black display characteristic than usual is displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates mainly to a method and apparatus for displaying an image using a spatial light modulator such as a liquid crystal panel.

[0002]

2. Description of the Related Art Conventional image display devices can be roughly classified into a self-luminous type and a light-receiving type. The self-luminous type is typified by using a CRT, and the light receiving type is typified by using a spatial light modulator such as a liquid crystal panel.

In general, the former self-luminous type can obtain a display having a wide dynamic range. Taking a CRT as an example, when displaying a black level, the output of the electron gun can be made as close to zero as possible, and the amount of light emitted from the phosphor can be made extremely small. On the contrary, when displaying the white level, the output of the electron gun is increased as the display area becomes smaller, so that the peak brightness with a feeling of brightness can be obtained.

On the other hand, a configuration example of a direct-view display device using, for example, a liquid crystal panel as a spatial light modulator (FIG. 9).
Shown in. Broadly speaking, the light emitting unit 101, the liquid crystal panel 102,
It is composed of a drive circuit 103. For the light emitting unit 101, for example, a cold cathode ray tube is used, and the liquid crystal panel 102 is illuminated from the back side. The drive circuit 103 forms an optical image on the liquid crystal panel 102 according to a video signal supplied from the outside,
The illumination light 104 is modulated.

Further, as a method for displaying a large screen image, a projection display device using a spatial light modulator is known.
In particular, recently, a projection display device using a liquid crystal panel has been developed, and FIG. 10 shows an example of the configuration of such a projection display device. Light emitting unit 110, liquid crystal panel 11
1, drive circuit 112, projection lens 113, screen 1
It is composed of 14. The light emitting unit 110 uses, for example, a light source in which a metal halide lamp 115 and a concave mirror 116 are combined. The illumination light 117 output from the light emitting unit illuminates the liquid crystal panel 111, is modulated by the optical image formed by the drive circuit 112, and the projection lens 113 enlarges and displays a large-screen image on the screen 114.

[0006]

The image display device using the spatial light modulator has a problem that the dynamic range of an image that can be displayed is relatively small.

The maximum white level obtained is determined by the product of the maximum efficiency of the spatial light modulator and the brightness of the illumination light. However, since the maximum efficiency of the spatial light modulator is determined by the characteristics of each element, a brighter light emitting portion must be used to make it brighter. In this case, it is necessary to brighten the entire area of the display screen, and the efficiency is lower than that in the case of brightening a part of the area. Therefore, the light emitting unit is large and the power consumption is large.

Further, as the brightness of the light emitting portion is increased in order to increase the brightness of the white level, the black display level is also increased, and the quality of the image is remarkably deteriorated.

That is, the displayable dynamic range is limited by the contrast of the spatial light modulator. For example,
In the case of an active matrix type twisted nematic liquid crystal panel, even a high one has a contrast ratio of about 500: 1, and it cannot be said that the characteristics are sufficient, especially when used in a projection display device.

At the same time, there is a problem in that the peak brightness cannot be made too bright due to the balance with the quality of black display and the size of the light emitting portion.

On the other hand, in the case of a display device using a liquid crystal panel, for example, the uniformity of black display is not so high. Display unevenness occurs due to variations in characteristics of each pixel due to gap unevenness of the liquid crystal panel, and the unevenness becomes remarkable particularly in a black display state. As a result, when an image in which a dark signal occupies a large area is displayed, display unevenness is generated and the quality is greatly degraded.

[0012]

In order to solve the above problems, a video display method of the present invention is a light emitting section capable of changing a light output level, and spatial light modulation for modulating output light of the light emitting section. Unit, a drive unit that drives the spatial light modulation unit according to a video signal, and a video signal processing unit that pre-processes a video signal input to the drive unit, and the video signal processing unit Peak level V of the video signal
_{When p} is detected and the peak level V _P is higher than a preset reference peak level V ₀ , the light emitting unit increases the light output level and the video signal processing unit decreases the amplitude of the video signal. When the peak level V _P is smaller than the reference peak level V ₀ , the light emitting unit reduces the light output level and the video signal processing unit increases the amplitude of the video signal. Input to the drive unit.

The video signal processing unit calculates the dark level period S _b for each frame period, and when the magnitude of S _b is larger than a preset threshold value S ₀ , the light emitting unit is Try to reduce the light output level.

[0014]

According to the above method, since the peak level of the video signal to be displayed is detected and the brightness of the light illuminating the spatial light modulator is changed in proportion to the peak level, the brightest one display screen is displayed. The spatial light modulator can be driven with the maximum efficiency with respect to the display unit. As a result, the dynamic range of the spatial light modulator can be always utilized to the maximum extent for driving, and a video display method with excellent gradation display characteristics can be provided. In addition, since the efficiency of the illumination light transmitted through the spatial light modulator is improved, a brighter display image can be realized, and an extremely large effect can be obtained.

Further, the period of the dark level of the video signal to be displayed is calculated, and when the area for displaying the dark video is large to some extent, the light output of the light emitting portion is reduced to make the display unevenness in the dark portion less noticeable. be able to.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the image display method of the present invention will be described below with reference to FIG. The image display method of the present invention can be applied to the direct-view type and projection type display devices using the spatial light modulator as shown in (FIG. 9) and (FIG. 10).

The standard of the video signal supplied to the display device
Peak level is the reference peak level V ₀And For example N
Considering various video signals of TSC, 100 IRE
Video signals with higher peak levels often appear
It On the contrary, if the image is dark, the peak level is 100.
Below IRE. Therefore, in this case, the reference peak level
V₀For example, you can select a signal level of 100IRE
It

Further, it is assumed that a light source capable of changing the light output is used for the light emitting section, and the reference light output level is L ₀ . Specifically, the light output level represents the brightness of light that illuminates the spatial light modulator.

First, the peak level V _p is detected at regular intervals of the video signal V _in supplied from the outside. The fixed cycle is a period corresponding to one screen display, and is one frame period for a TV signal.

Next, the gain G _s = V _p / V ₀ is calculated from the detected peak level V _p . The variable range of the gain G _s is set in advance, and the maximum gain G _max and the minimum gain G _{min are set.}
In the case of expressing by using, when a gain of G _max or more or G _min or less is calculated, these are limited to the value.

After calculating the gain G _s , the video signal level is modulated as V _c = V _in / G _s . However, V _in is the input video signal level. Modulated video signal V
_c is converted into a drive signal by an appropriate method to drive the spatial light modulator.

At the same time, the light output level L _out of the light emitting section is
Using the gain G _s , L _out = G _s × L ₀ . However, the light source used for the light emitting unit is one that can change the light output level L _out within the range of the minimum gain G _min to the maximum gain G _max with respect to the reference light output level L ₀ .

Therefore, maximum and minimum gains G _max and G
_min may be determined from the variable range of the light output level of the light source, for example. Further, it may be set so as to suppress, for example, a steep change in gain that causes an observer to perceive an uncomfortable feeling within the restricted range of the light source.

By repeating the above-described processing at regular intervals, it is possible to display a bright image having excellent gradation display characteristics and black display characteristics as compared with the conventional art.

The reason for this will be supplementarily described below. (Fig. 2)
Consider three types of video signal patterns having different peak levels as shown in FIG. One cycle T _{0 on the} horizontal axis corresponds to, for example, one frame cycle, and V ₀ is a reference peak level.

The video signal pattern 11 shown in FIG.
V _p1 peak level, V _p2 peak level of the video signal pattern 12 shown in FIG. (B), represents the peak level of the video signal pattern 13 shown in FIG. (C) as V _p3, V _p1 is It is assumed that V _p is larger than V ₀ , V _{p 2} matches V _0, and V _p3 is smaller than V ₀ .

Using FIG. 3, each video signal pattern 1
A method for driving the spatial light modulator when 1, 12, and 13 are given will be described. (FIG. 3) is the video signal level V
The correlation between _c and the transmittance T of the spatial light modulator is shown, (a) shows the case of the conventional method, and (b) shows the case of applying the image display method of the present invention. In the case of the conventional method of (a), the input video signal levels V _in and V _c match.
In any case, the maximum transmittance when the image signal level V _cmax, and to obtain a minimum transmittance when the image signal level V _cmin.

In the conventional method (a), the peak level V _p1
Is the maximum peak level in the input video signal, it is necessary to associate the peak level V _p1 with the video signal level V _cmax . Therefore, the peak levels V _p2 and V _p3 are
It is associated with signal levels below V _cmax . For example,
When a peak level lower than V _p1 is associated with V _cmax ,
When a signal having a high peak level such as V _p1 is input, there is a problem in that white crushing occurs.

As a result, the video signal patterns 11, 12,
The display corresponding to 13 is the range indicated by D1, D2, and D3.
Is displayed as the dynamic range and the peak level
Is V _p3The lower the value, the finer the gradation characteristics
And become difficult. Also, the peak level of the average video signal
Le V_p2, The characteristics around the maximum transmittance are
It is not used much and the efficiency of the displayed image is poor.
It will be a drive.

In the case of the video display method of the present invention of (b), the video signal level V _cmax and the reference peak level V ₀ are associated with each other. As a result, whether the peak level is V _P1 , V _P2 , or V _P3 , the gain G _s normalizes it, and associates each peak level with V _cmax . Therefore, when considering the display per screen, D'is always displayed regardless of the peak level.
The spatial light modulator can be driven by utilizing the dynamic range indicated by.

By the way, at the same time, the light output level L of the light emitting unit is
_{Since out} is changed as L _out = L ₀ × G _s using the gain G _s , the brightness corresponding to each peak level is correctly proportional to the signal level, and the image is displayed without any problem. It

From the above operation, the image display method of the present invention provides a method for fully utilizing the dynamic range of the spatial light modulator regardless of the peak level of the image signal,
Even with a video pattern having a low peak level, finer gradation display is possible.

The brightness corresponding to the peak level is
Since the maximum transmittance of the spatial light modulator is always used for display, there is an advantage in realizing brighter display. That is, in order to obtain the same brightness, it is possible to reduce the power consumption of the light source, and it is possible to realize a brighter display when comparing light sources having the same power consumption.

Next, the first embodiment of the display device to which the first embodiment of the image display method of the present invention is applied will be described with reference to FIG. This shows a configuration example of a direct-view type display device using a transmissive liquid crystal panel.

The liquid crystal panel 24 is illuminated from the back by the light emitting portion 23 which is a combination of the halogen lamp 21 and the condenser reflecting mirror 22. The drive circuit 25 forms an optical image on the liquid crystal panel 24 according to the video signal V _c , spatially modulates the illumination light 27, and displays an image.

The halogen lamp 21 is turned on by a lighting circuit 28 composed of a DC power source, and a light output control circuit 29 changes the output voltage of the lighting circuit 28 to change the light output level L _out.
Can be changed.

The video signal processing circuit 30 functions according to the above-mentioned video display method. The peak level detection circuit 31 detects the peak level V _p of the input video signal V _in . The gain calculation circuit 32 calculates the gain G _s from V _p . The amplitude modulation circuit 33 modulates the video signal V _in using G _s and outputs the video signal V _c to the drive circuit 25. The drive circuit 25 drives the liquid crystal panel 24 along the video signal V _c .

The gain calculation circuit 32 also outputs the gain G _s to the light output control circuit 29 at the same time. Light output control circuit 2
9 changes the light output level L _out of the light emitting unit 23 according to the gain G _s .

As described above, since the video signal processing circuit functions according to the video display method described above, the display device having the configuration shown in FIG. 4 has a wide dynamic range and excellent gradation characteristics in a dark portion. , It is possible to display bright high quality images.

Next, a second embodiment of the display device to which the first embodiment of the image display method of the present invention is applied will be described with reference to FIG. This shows a configuration example of a projection display device using a transmissive liquid crystal panel.

The liquid crystal panel 54 is illuminated from the back side by the light emitting portion 53 which is a combination of the halogen lamp 51 and the condenser reflecting mirror 52. The drive circuit 55 forms an optical image on the liquid crystal panel 54 according to the video signal V _c , and spatially modulates the illumination light 57. The optical image on the liquid crystal panel 54 is projected by the projection lens 58.
Is enlarged and projected, and a large-screen image is displayed on the screen 59. The video signal processing circuit 60, the lighting circuit 61, and the light output control circuit 62 are the same as those described in (FIG. 4).

The projection type display device having the structure shown in FIG.
Due to the effect based on the image display method of the present invention, it is possible to display a bright high-quality image having a wide dynamic range and excellent gradation characteristics in a dark portion.

In particular, the projection type display device as shown in FIG. 5 has a problem that the peak brightness is insufficient, and when displaying a dark image, a sufficient display quality is not obtained particularly in the gradation characteristic. There is a problem. In the case of using the conventional light emitting section having a constant light output level, it is difficult to solve these two problems at the same time.

However, the image display method of the present invention makes it possible to display a brighter image by increasing the light output of the light emitting unit from the steady state with respect to a bright image at the peak level. In addition, the light output of the light emitting unit is reduced with respect to an image with a dark peak level, and it is possible to drive by fully utilizing the dynamic range of the spatial light modulator. Therefore, the display quality of a dark image can be greatly improved, and a bright projected image can be efficiently obtained by using a light source of low power consumption, and an extremely large effect can be obtained.

The second embodiment of the video display method of the present invention will be described below. When a liquid crystal panel having a low contrast is used as the spatial light modulator, for example, when the dark display area covers a large area, the image quality is significantly deteriorated due to the effect of black floating. In particular, during black raster display, display unevenness occurs due to the influence of in-plane variations of various characteristics. The image display method described below is effective for such a problem.

The procedure will be described with reference to FIG. However, (FIG. 6) shows a processing procedure per frame. Let Vin _(t) be the input video signal level. However,
The time t is considered for each frame, t = 0 is set as the start time of the video signal of one frame, and at t = t _f ,
It is assumed that one frame of video signal ends. In order to simplify the explanation, consider discrete data obtained by sampling a video signal at a specific clock.

First, the dark level period S _b from one screen
To detect. The dark level period refers to an area in which a dark image is displayed on one screen. For example, it is possible to calculate the period in which the signal level is darker than a set dark signal level V _b within one frame. Therefore, t = the period of one frame 0 to t _f, compares the V _b input video signal level V _{in (t),} the time period by adding the S _b If V _{in (t)} is darker than V _b To calculate.

Next, the threshold value S ₀ is set in advance for the dark level period, and the calculated dark level period S _b is S.
Determine if it is greater than ₀ . When S _b is larger than S _{0, a} value G ₀ smaller than 1 is given to the gain G _b . In other cases, the gain G _b = 1. Using this gain G _b , the video signal level V _c is V _c = V _in
/ G _b as well as the light output level L of the light emitting unit
_{Let out} be L _out = G _b × L ₀ . However, V _in is the input video signal level and L ₀ is the reference light output level. The modulated video signal _Vc is converted into a drive signal by an appropriate method to drive the spatial light modulator.

That is, when the dark level period S _b exceeds the threshold value S ₀ , it is determined that black floating or display unevenness is conspicuous, and the brightness of the light emitting portion is instantly set to a gain G _b smaller than 1.
To lower it. At the same time, the drive signal level is gain G
Modulate with the reciprocal of _b . As a result, it is possible to make black floating and display unevenness in the dark level display section less noticeable without affecting the display of the light level.

Particularly, when considering the black raster display, it is not necessary to modulate the video signal with the gain G _b . At the moment when it is detected that a black raster image signal is input, only the light output level of the light emitting unit may be reduced to a predetermined brightness.

Next, the first embodiment of the display device to which the second embodiment of the image display method of the present invention is applied will be described with reference to FIG. This is except for the video signal processing circuit 71.
It has the same configuration as the direct-view display device using the transmissive liquid crystal panel shown in FIG.

In particular, the function of the video signal processing circuit 71 will be described. The video signal processing circuit functions according to the above-mentioned video display method. Dark level period calculation circuit 72 is supplied with a dark signal level V _b, by comparing the input video signal V _in and V _b for outputting a dark level period S _b for each frame. The dark level period comparison circuit 73 is provided with the dark level period threshold value S ₀ , and if S _b is smaller than S ₀ , the gain G _s = 1 is set,
If S _b is larger than S _{0, a} gain G _s smaller than 1 is output. Upon receiving this gain G _s , the amplitude modulation circuit 74 modulates the input video signal V _in and outputs the video signal V _c , and the drive circuit 25 drives the liquid crystal panel 24 appropriately. At the same time, the gain G _s is also output to the light output control circuit 29, and the light output level L _out of the light emitting unit 23 is changed according to the gain G _s .

As described above, the video signal processing circuit 71 functions according to the video display method described above (FIG. 7).
When a dark image or a black raster is displayed, the display device having the configuration shown in (3) can display a high-quality image without making black floating and display unevenness noticeable.

Next, a second embodiment of the display device to which the second embodiment of the image display method of the present invention is applied will be described with reference to FIG. This is except for the video signal processing circuit 81.
It has the same configuration as the projection type display device using the transmissive liquid crystal panel shown in FIG.

The video signal processing circuit 81 has the same function as that used in the direct-view display device described in (FIG. 7). Therefore, the projection type display device having the configuration shown in (FIG. 7) has the effect based on the image display method of the present invention that, when a dark image or a black raster is displayed, black floating and display unevenness are conspicuous. It is possible to display a high-quality image without any trouble. This can obtain a greater effect when applied to a projection display device that illuminates a liquid crystal panel with particularly strong light.

By the way, the video display method of the present invention described with reference to (FIG. 1) and (FIG. 6) always considers the continuity of the video signal and always detects the information about the video signal per frame. Then, it was explained that the video signal is modulated and the output light of the light source is controlled. Therefore, there is a strict time lag between the series of video signal processing steps and the control of the light output level of the light emitting unit.

Therefore, if this time delay becomes a problem, a frame memory can be adopted to eliminate the time delay. That is, while detecting the peak level of the video signal or calculating the dark level period, the video signal is stored in the frame memory, the gain is calculated, and then the modulation of the video signal stored in the frame memory and the optical output of the light emitting unit are performed. It is sufficient to simultaneously control the above and display the image.

In the first embodiment of the image display method of the present invention described with reference to FIG. 1, the gain G _s does not have to be continuously changed. By controlling so that the value of G _s can be discretely taken, G _s does not always fluctuate, and a more stable high-quality image can be displayed in accordance with the peak level range.

Further, (FIG. 4), (FIG. 5), (FIG. 7),
In each of the embodiments of the image display device shown in (FIG. 8), the example in which the halogen lamp is used for the light emitting portion has been described, but the light source is not particularly limited thereto. Any light source that can relatively easily and instantly adjust light may be used. In particular, a metal halide lamp is superior in efficiency and color reproducibility as compared with other lamps, and therefore may be used. In this case, by using a lighting circuit that can control the lamp power,
The light output level can be changed.

Further, although the embodiment using the liquid crystal panel has been described for the spatial light modulator, the same effect can be obtained even when another spatial light modulator is used.

[0061]

As described above, according to the present invention, the dynamics of the spatial light modulator are controlled by controlling the video signal and the light output of the light emitting unit in accordance with the peak level of the input video signal. It is possible to realize high-quality display that makes full use of the range. Further, by performing the same control in accordance with the dark level period of the input video signal, it is possible to reduce black floating and display unevenness when a dark video is displayed, and to provide a video with high display quality.

Further, by applying the image display method of the present invention to a direct-view type or projection type display device using a spatial light modulator, a bright and high-quality image excellent in gradation characteristics and dark level display quality is obtained. A display device can be provided.

[Brief description of drawings]

FIG. 1 is a flow chart for explaining an embodiment of a video display method of the present invention.

FIG. 2 is a schematic diagram showing time-amplitude distributions of three types of video signals having different peak levels.

FIG. 3 is a schematic diagram showing a video signal level-transmittance characteristic of a spatial light modulator.

FIG. 4 is a schematic configuration diagram showing an embodiment of a video display device of the present invention.

FIG. 5 is a schematic configuration diagram showing another embodiment of the video display device of the present invention.

FIG. 6 is a flowchart for explaining another embodiment of the image display method of the present invention.

FIG. 7 is a schematic configuration diagram showing another embodiment of the video display device of the present invention.

FIG. 8 is a schematic configuration diagram showing another embodiment of the video display device of the present invention.

FIG. 9 is a schematic configuration diagram showing an embodiment of a conventional video display device.

FIG. 10 is a schematic configuration diagram showing another embodiment of a conventional image display device.

[Explanation of symbols]

 21 Halogen Lamp 22 Condensing Reflector 23 Light Emitting Section 24 Liquid Crystal Panel 25 Drive Circuit 28 Lighting Circuit 29 Light Output Control Circuit 30 Video Signal Processing Circuit 31 Peak Level Detection Circuit 32 Gain Calculation Circuit 33 Amplitude Modulation Circuit 58 Projection Lens 59 Screen

Claims (16)

[Claims] 1. A light emitting section capable of changing a light output level, a spatial light modulating section for modulating output light of the light emitting section, and a driving section for driving the spatial light modulating section according to a video signal. A video signal processing unit for pre-processing a video signal input to the driving unit, the video signal processing unit detecting a peak level V _p of the video signal in a predetermined period, and the peak level V _P is preset. Reference peak level V ₀
If it is larger, the light emitting unit increases the optical output level, and the video signal processing unit reduces the amplitude of the video signal and inputs the video signal to the driving unit, and the peak level V _P
Is smaller than the reference peak level V ₀ , the light emitting unit lowers the light output level, and the video signal processing unit increases the amplitude of the video signal and inputs it to the driving unit. Display method. 2. When the reference light output level of the light emitting section is L ₀ , a gain G _s of approximately G _s = V _p / V _{0 is} obtained using the detected peak level V _p and reference peak level V _0. Seeking,
The video signal processing unit outputs a video signal of approximately V _c = V _in / G _s to the drive unit, and the light emitting unit outputs the optical output level L _out to approximately L _out = L.
The image display method according to claim 1, wherein the image display method is changed so as to be ₀ × G _s . 3. When the reference light output level of the light emitting section is L ₀ , the gain G _s which is discretely determined according to the magnitude of the detected peak level V _p is selected, and the video signal processing section is set to approximately V. _c
= A V _in / G _s becomes a video signal and outputs to the drive unit, the light emitting unit is a video display method according to claim 1, wherein the changing so that the optical output level L _{ou t} substantially _{L out = L 0 × G s} . 4. A video signal for a predetermined period of time is held while detecting a peak level V _P, and after detecting the peak level V _p , control of an optical output level of a light emitting section, amplitude modulation of the held video signal, and The video display method according to claim 1, wherein the spatial light modulator is driven by a video signal. 5. A light emitting means capable of changing a light output level, a spatial light modulating means for modulating output light of the light emitting means, and a driving means for driving the spatial light modulating means according to a video signal. A video signal processing means for pre-processing a video signal input to the driving means, wherein the video signal processing means has a peak level V of the video signal in a predetermined period.
_{When p} is detected and the peak level V _P is higher than a preset reference peak level V ₀ , the light emitting means increases the light output level and the video signal processing means decreases the amplitude of the video signal. Input to the drive means,
When the peak level V _P is lower than the reference peak level V ₀ , the light emitting means lowers the light output level, and the video signal processing means increases the amplitude of the video signal and inputs it to the driving means. Video display device characterized by. 6. The peak level V detected by the video signal processing means when the reference light output level of the light emitting means is L _{0.
Using p} and the reference peak level V ₀ , a gain G _s of approximately G _s = V _p / V ₀ is obtained, the gain G _s is output to the light emitting means, and approximately V _c = V _in / G _s . outputs the image signal to the drive means, said light emitting means is a video display apparatus according to claim 5, wherein the changing so that the optical output level L _out substantially _{L out = L 0 × G s} . 7. The video signal processing means detects the peak level V when the reference light output level of the light emitting means is L _0.
Select a gain G _s that is discretely determined according to the magnitude of _p ,
Outputs the gain G _s to the light emitting means, a substantially V _c
6. The image display device according to claim 5, wherein a video signal of = V _in / G _s is output to the driving means, and the light emitting means changes the light output level L _out to approximately L _out = L ₀ × G _s . 8. The video signal processing means includes a video signal holding means, stores an input video signal in the video signal holding means while detecting a peak level, and after detecting the peak level, changes the optical output level of the light emitting means. The image display device according to claim 5, wherein the control, the amplitude modulation of the image signal stored in the image signal holding means, and the driving of the spatial light modulator by the image signal are performed. 9. The image display device according to claim 5, further comprising image enlarging means for enlarging and projecting a display image of the spatial light modulating means on a screen. 10. A light emitting section capable of changing a light output level, a spatial light modulating section for modulating output light of the light emitting section, and a driving section for driving the spatial light modulating section according to a video signal. And a video signal processing unit for pre-processing a video signal input to the driving unit, wherein the video signal processing unit calculates a dark level period S _b for each frame period, and the magnitude of S _b is The image display method, wherein the light emitting unit reduces the light output level when the threshold value is larger than a preset threshold value S ₀ . 11. When a reference light output level of the light emitting section is L ₀ , a gain G _b smaller than 1 is set in advance, and a dark level period S _b is larger than a preset threshold value S ₀ , The video signal processing unit outputs a video signal of substantially V _c = V _in / G _s to the drive unit, and the light emitting unit changes the light output level L _out to substantially L _out = L ₀ × G _s. 10. The image display method described in 10. 12. A dark level period S _b is calculated while holding a video signal for a predetermined period, and the dark level period S _b is held.
The image display method according to claim 10, wherein after the calculation of _b , the control of the light output level of the light emitting unit and the driving of the spatial light modulator by the held image signal are performed. 13. A light emitting means capable of changing a light output level, a spatial light modulating means for modulating an output light of the light emitting means, and a driving means for driving the spatial light modulating means according to a video signal. A video signal processing means for pre-processing a video signal input to the driving means, wherein the video signal processing means calculates a dark level period S _b for each frame period, and the magnitude of S _b is The image display device, wherein the light emitting means reduces the light output level when the threshold value is larger than a preset threshold value S ₀ . 14. When a reference light output level of the light emitting means is L ₀ , a gain G _b smaller than 1 is set in advance, and a dark level period S _b is larger than a preset threshold value S ₀ , The video signal processing means outputs the gain G _s to the light emitting means and also outputs a video signal of approximately V _c = V _in / G _s to the driving means, and the light emitting means outputs the light output level L _out to approximately L _out. = L ₀ × G _s and so as an image display apparatus according to claim 13, wherein changing. 15. The video signal processing means includes a video signal holding means, and stores the input video signal to the video signal holding unit while calculating the period S _b of dark level, after the calculation of the period S _b of the dark level 14. The image display device according to claim 13, wherein the optical output level of the light emitting means is controlled and the spatial light modulator is driven by the image signal stored in the image signal holding means. 16. The image display device according to claim 13, further comprising image enlarging means for enlarging and projecting a display image of the spatial light modulating means on a screen.