JP2002311381A - Picture display device and picture display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the brightness distribution of a displayed picture is not uniform because there are an area which meets a total reflection condition and an area which never meets the condition on the reflection surface of a projecting optical element. SOLUTION: In a picture display device having a picture display element 102 for displaying a picture corresponding to a supplied signal and the projecting optical element 108 reflecting picture light emitted from this picture displaying element and projecting it to the eyeballs of an observer, there are the first area 109(a) which meets the total reflection condition with respect to the picture light and the second area 109(b) which never meets the condition on the reflection surface 108(b) of the projecting optical element, and a luminance adjusting means 110 which adjusts the luminance of light beams to be reflected by the first area lower than that of light beams to be reflected by the second area among picture lights incident on the projecting optical element from the picture display element.

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 mounted on the head or face of an observer and projecting an image on the observer's eyeball.

[0002]

2. Description of the Related Art FIG. 6 shows a head mounted image display device (head mounted display, hereinafter referred to as HMD) 7.
01 is shown. The observer can wear the HMD 701 on his or her head or face and enjoy the images and sounds displayed on the built-in image display device. At this time, the wearer is shielded from the surrounding situation, and a high immersion feeling can be obtained.

[0003] The HMD 701 includes a main body 711 for displaying an image to an observer, and a crane 712 for mounting on an observer's head.

When the observer wears the HMD 701 like eyeglasses, an image displayed on an image display element such as an LCD installed in the main body 711 is passed through the left and right opening windows 716 of the main body 711. It can be observed as a large screen image by the enlargement effect of the projection optical system installed inside.

FIG. 7 shows a cross section when the HMD 701 is cut along the central optical axis. Reference numeral 702 denotes a transmission-type image display element that is driven according to input image information and displays an image by transmitting an illumination light beam. Here, a liquid crystal display element (LCD) is used.

Reference numeral 703 denotes a backlight for irradiating the LCD 702 with illumination light, and a flat fluorescent tube is used. Reference numeral 704 denotes an electric circuit board for driving the LCD 702 and the backlight 703.

Reference numeral 705 denotes a projection prism for enlarging and projecting image light (illumination light modulated by the LCD 702) emitted from the LCD 702 onto the eyeball of the observer.

[0008] The image light emitted from the LCD 702 first passes through the first surface 706 of the projection prism 705 and is reflected by the second surface 707. At this time, within the range of the effective beam diameter on the second surface 707, the condition for total reflection of light beams is satisfied, and almost all incident image light beams are reflected.

The image light reflected on the second surface 707 is reflected again on the third surface 708 of the prism 705. The third surface 708 does not satisfy the condition for total reflection of light rays, and a reflection film for reflecting light rays is formed on the third surface 708.

[0010] The image light reflected on the third surface 708 passes through the second surface 707 of the projection prism 705 and passes through the mask 70.
After unnecessary light rays are cut at 9, the light rays are projected on the eyeball of the observer.

As described above, the second surface 707 has a portion satisfying the total reflection condition and a portion not satisfying the total reflection condition depending on the incident angle of the image light. At this time, the portion that satisfies the condition of total reflection is designed to satisfy the condition of total reflection by utilizing the difference in the refractive index between the projection prism 705 and air.

[0012]

The above-mentioned conventional image display apparatus is a transmissive LCD having a relatively large screen size.
Is used. Therefore, it is possible to design the second surface 707 of the projection prism 705 so as to satisfy the condition of total reflection of light rays.

However, the HMD is strongly required to be smaller and lighter, and conversely, is required to have a higher resolution and a larger angle of view.

In recent years, in order to display more information, a reflection type image display element which displays image information by reflecting incident light has been developed.

A major feature of the reflection type image display device is that a high resolution device with a small screen size can be manufactured. Specifically, a diagonal of 0.5 inch or less (about 12 mm) and a resolution of SVGA (800 × 600 dots) can be manufactured.

In order to provide an observer with a large-screen image using the small-sized reflective image display device, a high magnification is required for the projection prism as an optical element.

However, in such a case, the first surface 706 is located above the second surface 707 of the projection prism 705.
Therefore, it is difficult to design to satisfy the condition of total reflection of the light beam transmitted through the first prism 705.
Region 709 (a) that satisfies the condition of total reflection for the light beam transmitted through the surface 706 of FIG.
09 (b) is present.

A configuration is also conceivable in which a reflection film is deposited on a region of the second surface 707 which does not satisfy the total reflection condition, thereby totally reflecting light rays. However, in this case, the edge of the vapor-deposited film exists within the effective diameter of the light beam, and as shown in FIG. 8, the edge E is observed by the observer, and the quality of the displayed image is significantly reduced.

Further, a configuration is also conceivable in which a reflective film is vapor-deposited on the entire surface within the effective diameter including the region satisfying the total reflection condition on the second surface 705.

However, the effective diameter area where the light beam transmitted through the first surface 706 is reflected on the second surface 705 and the light beam reflected on the third surface 708 is transmitted and projected to the observer's eyeball. When the reflective film is deposited over the entire effective diameter, there arises a problem that the light beam does not transmit and the observer cannot observe the image.

[0021]

According to a first aspect of the present invention, there is provided an image display element for displaying an image corresponding to a supplied signal, and an image emitted from the image display element. In an image display apparatus having a projection optical element for reflecting light and projecting the light onto an eyeball of an observer, a first area satisfying a total reflection condition for image light and a total reflection condition are formed on a reflection surface of the projection optical element. There is a second area that is not satisfied, and of the image light that enters the projection optical element from the image display element, the luminance of a light beam that is to be reflected by the first area is reflected by the second area. Brightness adjusting means for lowering the brightness of the light beam.

That is, the brightness of the image light (light ray) reflected by the first area in the projection optical element is changed by the brightness adjusting means such as an ND filter into the image reflected by the second area. By making the luminance lower than the brightness of the light (light ray), the image light reflected on the first area and projected on the observer's eyeball and the image light reflected on the second area and projected on the observer's eyeball It is possible to reduce or almost eliminate the luminance difference from the image light to be performed. For this reason, a high-quality display image without a sense of incongruity in the brightness distribution or a uniform brightness distribution is provided without performing a process for generating an edge of the vapor-deposited film in the viewing field of the projection optical element. It is possible to do.

In the second invention of the present application, the illumination light source includes:
An image display element for displaying an image corresponding to the supplied signal and modulating the illumination light from the illumination light source, and a projection optical element for reflecting the image light emitted from the image display element and projecting the image light on the eyeball of the observer In the image display device having: a first region that satisfies the total reflection condition with respect to the image light, and a second region that does not satisfy the total reflection condition with respect to the image light. Among them, the brightness of the light beam to be modulated by the image light reflected by the second region is lower than the brightness of the light beam to be modulated by the image light reflected by the first region.

That is, in the projection optical element, the first
The brightness of the illumination light (light ray) to be modulated by the image display element on the image light reflected by the area, and the illumination light to be modulated by the image display element on the image light reflected by the second area. By making the luminance lower than the (light) luminance, the image light reflected on the first area and projected on the observer's eyeball and the image light reflected on the second area and projected on the observer's eyeball This makes it possible to reduce or almost eliminate the luminance difference from the image light. For this reason, a high-quality display image without a sense of incongruity in the brightness distribution or a uniform brightness distribution is provided without performing a process for generating an edge of the vapor-deposited film in the viewing field of the projection optical element. It is possible to do.

In the second aspect of the present invention, the brightness of the illumination light, which is modulated into the image light reflected by the first area, is reduced by using a brightness adjusting means such as an ND filter. Is also good.

In the first and second aspects of the present invention, when the projection optical element is housed in the housing, light transmitted through the second area of the reflection surface of the projection optical element is transmitted to the housing. An anti-reflection means for preventing reflection on the inner surface may be provided to suppress the generation of reflected light on the inner surface of the housing, which causes factors such as stray light and flare.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows an HMD (image display device) 101 according to a first embodiment of the present invention.
The HMD 101 is cut along a cross section parallel to the observation optical axis.

In this figure, reference numeral 102 denotes an image display element which is driven in accordance with a supplied image signal and which displays an image by reflecting and modulating incident illumination light and emitting the same. Liquid crystal display (LCD)
Is used.

Reference numeral 103 denotes an illumination light source for illuminating the image display element 102. In this embodiment, an LED is used.

Reference numeral 104 denotes a reflecting member for reflecting the illumination light emitted from the LED 103 to make it substantially parallel light. L
A part of the illumination light emitted from the ED 103 is
The light is reflected at 4 and becomes substantially parallel light, and enters the polarizing plate 105. The illumination light that has entered the polarizing plate 105 is converted into linearly polarized light, and then enters the illumination prism 106.

The illumination light, which has become substantially parallel light, enters the first surface 106 (a) of the illumination prism 106 and is refracted. Next, the light reaches the second surface 106 (b) and is totally reflected. Second
Since the surface 106 (b) satisfies the condition of total reflection with respect to the illumination light, almost all the illumination light is reflected, and the third surface 1 (b) is reflected.
06 (c), and enters the reflective LCD 102.

The reflection type LCD 102 controls the polarization direction of the incident light beam according to the input image signal to display an image.

The HMD 101 includes an LCD 10
2 is supplied from an image information supply device such as a personal computer, a video, a television, or a DVD player.

Light rays (image light including image information) reflected and emitted by the reflection type LCD 102 are again emitted to the illumination prism 10.
6 is incident on the third surface 106 (c) of FIG.
The light passes through (b) and exits from the illumination prism 106. Thereafter, when the image light is transmitted through the exit polarizing plate 107, only the image information component is transmitted, and the observation prism (projection optical element)
108.

The first surface 108 of the observation prism 108
The image light incident on (a) is reflected by the upper portion of the second surface 108 (b). The image light reflected on the second surface 108 (b) is reflected again on the third surface 108 (c), and then passes through a lower portion of the second surface 108 (b) to be observed. Is guided to the eyeball (not shown) of the person.

The image light is subjected to the function of enlarging the image displayed on the reflection type LCD 102 during such repeated transmission, reflection, reflection, and transmission, so that the observer can observe the image on the large screen. Can be.

Here, the reflection type LCD 102 used in this embodiment is a high resolution LCD with a small screen size.
More specifically, the diagonal is 0.5 inch or less (about 12 mm) and has a resolution of SVGA (800 × 600 dots). In order to provide an observer with a large screen image using the reflective LCD 102 having the small screen size, the observation prism 108 of the present embodiment is required to have a high magnification.

Therefore, in the region near the upper end of the second surface 108 (b) of the observation prism 108, the first surface 108
It is difficult to design the image light that has transmitted through (a) to satisfy the condition of total reflection. Therefore, the second surface 108 (b) of the observation prism 108 of the present embodiment is provided on the first surface 108 (b).
There is a region (first region) 109 (a) that satisfies the total reflection condition for the image light transmitted through (a) and a region (second region) 109 (b) that does not satisfy the total reflection condition. I do.

FIG. 2 is a graph plotting the reflectance of the optical material used for the observation prism 108 with respect to the incident angle.

When the incident angle θ is incident at a shallow angle of about 40 ° or more, the incident light is totally reflected. When the angle of incidence is smaller than that, the light beam is partially transmitted instead of being totally reflected. However, the reflectivity does not change steeply with respect to the incident angle, but changes relatively slowly (that is, gradually).

Therefore, the observed image also has a portion formed by the image light reflected in the region satisfying the total reflection condition,
Although the brightness does not suddenly change between the portion formed by the image light reflected in the region that does not satisfy the total reflection condition, there is a luminance distribution.

For this reason, the image light itself incident on the observation prism 108 has a luminance distribution, and the second surface 108 (b)
The ND filter (brightness adjusting means) 110 is arranged between the illumination prism 106 and the observation prism 108 so that the brightness of the image to be observed becomes substantially uniform by canceling out the brightness distribution due to the reflectance distribution. .

Here, FIG. 3 (a) shows the observation prism 1
08 shows the luminance distribution of light rays reflected on a region satisfying the total reflection condition and a region not satisfying the total reflection condition on the second surface 108 (b). The left side of the one-dot chain line in the figure is the luminance distribution of light rays reflected in a region satisfying the total reflection condition, and the right side is the luminance distribution of light rays reflected in a region not satisfying the total reflection condition.

As can be seen from this figure, the light rays reflected in the area satisfying the total reflection condition have high luminance, and the light rays reflected in the area not satisfying the total reflection condition have low luminance and the incident angle of the light ray becomes smaller. The brightness of the reflected light is lower.

FIG. 3B shows a density distribution (solid line) of the ND filter 110 and a luminance distribution (dotted line) of image light passing therethrough. Regarding the ND filter 110, the left side of the one-dot chain line in the figure is the density distribution of a portion through which light rays to be reflected in a region satisfying the total reflection condition are transmitted, and the right side is reflected in a region not satisfying the total reflection condition. This is a density distribution of a portion through which a light beam passes.

As can be seen from this figure, the ND filter 1
10, the density of a portion through which light rays to be reflected in a region satisfying the total reflection condition is transmitted is high, the density of a portion through which light rays to be reflected in a region not satisfying the total reflection condition is transmitted is low, and total reflection is performed. The density becomes lower as the angle of incidence of the light beam incident on the area not satisfying the condition becomes smaller.

In accordance with the gentle change in the luminance distribution due to the reflectance distribution near the dashed line, ND
The change in the density distribution of the filter 110 from the high density area to the low density area is also gentle.

As a result, of the image light transmitted through the ND filter 110, the brightness of the light rays that will be reflected in the area that satisfies the condition of total reflection is low, and the light rays that will be reflected in the area that does not satisfy the condition of total reflection. Has a higher luminance, and the luminance becomes higher as the angle of incidence on a region where the total reflection condition of the light ray is not satisfied becomes smaller.

Therefore, as shown in FIG.
The luminance distribution of the image light that passes through the D filter 110 and enters the observation prism 108 and the luminance distribution due to the reflectance distribution of the second surface 108 (b) are canceled out, and the luminance (illuminance) of the entire image is substantially reduced. Become uniform.

The second surface 10 of the observation prism 108
In FIG. 8B, about 20 to 30% or more of the light rays are reflected in the region 109 (b) where the total reflection condition is not satisfied, depending on the incident angle of the light rays, and guided to the eyeball of the observer. However, about 70 to 80% of the remaining rays are in the region 109 which does not satisfy the total reflection condition.
(B) is transmitted and emitted, and the emitted observation prism 1
The light beam transmitted through the second surface 108 (b) of FIG. 08 reaches the inner surface of the rear cover (casing) 111.

In the present embodiment, the light-shielding line shape 1
12 are formed. Accordingly, the light beam that has reached the rear cover 111 is irregularly reflected by the light-shielding line shape 112 and does not enter the observation prism 108 again.

Therefore, the light reflected by the rear cover 111 and incident again on the observation prism 108 is reflected by the prism 10.
It becomes stray light that repeats reflection within 8 and is emitted to the observer's eyeball, thereby preventing deterioration in image quality due to being observed as a flare.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
1 illustrates a configuration of an HMD (image display device) 101 according to an embodiment, in which the HMD 101 is cut along a cross section parallel to an observation optical axis. In the present embodiment, components common to the first embodiment are denoted by the same reference numerals as those in the first embodiment.

In this embodiment, the ND filter 110 for adjusting the luminance distribution of the image light in the first embodiment is removed.
Between the LED 103 and the illumination prism 106, ie, L
N in the optical path of the illumination light from the ED 103 to the LCD 102
A D filter (luminance adjusting means) 130 is provided.

Here, FIG. 5 (a) shows the observation prism 1
08 shows the luminance distribution of light rays reflected on a region satisfying the total reflection condition and a region not satisfying the total reflection condition on the second surface 108 (b). The left side of the one-dot chain line in the figure is the luminance distribution of light rays reflected in a region satisfying the total reflection condition, and the right side is the luminance distribution of light rays reflected in a region not satisfying the total reflection condition.

As can be seen from the figure, the light rays reflected in the area satisfying the total reflection condition have high luminance, and the light rays reflected in the area not satisfying the total reflection condition have low luminance and the incident angle of the light ray decreases. The brightness of the reflected light is lower.

FIG. 5B shows a density distribution (solid line) of the ND filter 130 and a luminance distribution (dotted line) of illumination light passing therethrough. Regarding the ND filter 130, the left side of the one-dot chain line in the figure is a density distribution of a portion through which light rays to be reflected in a region satisfying the total reflection condition are transmitted, and the right side is reflected in a region not satisfying the total reflection condition. This is a density distribution of a portion through which a light beam passes.

As can be seen from this figure, the ND filter 1
The density of a portion where light rays to be reflected in a region satisfying the total reflection condition in 30 is transmitted is high, the density of a portion of a light beam to be reflected in a region not satisfying the total reflection condition is transmitted is low, and total reflection is performed. The density becomes lower as the angle of incidence of the light beam incident on the area not satisfying the condition becomes smaller.

In accordance with the gentle change in the luminance distribution due to the reflectance distribution near the dashed line, ND
The change in the density distribution of the filter 130 from the high density region to the low density region is also gentle.

As a result, of the illumination light transmitted through the ND filter 130, the brightness of the light rays that will be reflected in the area that satisfies the condition of total reflection is low, and the light rays that will be reflected in the area that does not satisfy the condition of total reflection. Has a higher luminance, and the luminance becomes higher as the angle of incidence on a region where the total reflection condition of the light ray is not satisfied becomes smaller.

Accordingly, the luminance distribution of the image light emitted from the LCD 102 is determined according to the luminance distribution of the illumination light, and the luminance distribution of the image light incident on the observation prism 108 and the reflection of the second surface 108 (b). The luminance distribution due to the rate distribution is canceled, and the luminance (illuminance) of the entire image becomes substantially uniform, as shown in FIG.

In the present embodiment, instead of forming the light-shielding line shape 112 on the rear cover 111 as in the first embodiment, a felt member 113 is adhered as antireflection means.

The felt member 112 is a material generally used as an anti-reflection member inside the photographic lens barrel, and a high anti-reflection effect can be expected.

As shown in FIG. 4, since the light beam transmitted through the observation prism 108 is absorbed by the felt member 113, the reflected light enters the prism 108 again and is observed as a flare. Can be prevented.

(Third Embodiment) In the second embodiment,
The case where the ND filter 130 is disposed in the illumination light path to cancel the luminance distribution due to the reflectance distribution of the second surface 108 (b) of the observation prism 108 has been described.
By appropriately changing the shapes of D103 and the reflecting member 104 to make the luminance distribution of the illumination light as shown in FIG. 3B, the luminance distribution due to the reflectance distribution of the second surface 108 (b) is canceled. Then, the brightness of the entire image may be made substantially uniform.

Further, by adding another lens system in the optical path of the illuminating light from the LED 103 to the LCD 102, the illuminating light has a luminance distribution, and the luminance distribution based on the reflectance distribution of the second surface 108 (b). May be canceled to make the luminance of the entire image substantially uniform.

Further, in the second embodiment, the case where the felt member is used as the anti-reflection member has been described. However, other members may be used as long as the member prevents reflection of light rays.

Further, in each of the above embodiments, the brightness and total brightness of the image light reflected on the second surface 108 (b) of the observation prism 108, which forms the image to be finally observed, which satisfies the condition of total reflection, are obtained. The case where the density of the ND filter is set so that the luminance of the image light reflected in the area that does not satisfy the reflection condition is uniform has been described. Even if there is a slight difference between the brightness of the image light reflected in the region that does not satisfy the reflection condition and the brightness of the image light, it is sufficient that the brightness does not cause any discomfort to the observer, and such ND filter density setting may be performed.

In each of the above embodiments, the case where a reflection type image display element is used has been described. However, the present invention relates to a transmission type image display element or a self-luminous type image display element which does not require an illumination system. The same can be applied when used.

[0070]

As described above, according to the first aspect of the present invention, the image light reflected by the first area satisfying the total reflection condition in the projection optical element by the brightness adjusting means such as the ND filter. Since the brightness of the (light) is set lower than the brightness of the image light (light) that is reflected in the second area that does not satisfy the condition of total reflection, the light is reflected in the first area and is reflected by the observer. The brightness difference between the image light projected on the eyeball and the image light reflected on the second region and projected on the observer's eyeball can be reduced or almost eliminated. For this reason, a high-quality display image without a sense of incongruity in the brightness distribution or a uniform brightness distribution is provided without performing a process for generating an edge of the vapor-deposited film in the viewing field of the projection optical element. can do.

Further, according to the second aspect of the present invention, the luminance of the illumination light (light ray) to be modulated by the image display element to the image light reflected in the first area satisfying the total reflection condition in the projection optical element. Is made lower than the luminance of the illumination light (light ray) that is modulated by the image display element into the image light reflected by the second area that does not satisfy the total reflection condition, so that the light is reflected by the first area. As a result, the difference in brightness between the image light projected on the observer's eye and the image light reflected on the second region and projected on the observer's eye can be reduced or almost eliminated. For this reason, a high-quality display image without a sense of incongruity in the brightness distribution or a uniform brightness distribution is provided without performing a process for generating an edge of the vapor-deposited film in the viewing field of the projection optical element. can do.

In the first and second aspects of the present invention, when the projection optical element is housed in the housing, light transmitted through the second region on the reflection surface of the projection optical element is transmitted to the housing. If anti-reflection means for preventing reflection on the inner surface is provided, it is possible to suppress the generation of reflected light on the inner surface of the housing, which causes factors such as stray light and flare, and to provide a higher quality display image. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view of an HMD according to a first embodiment of the present invention.

FIG. 2 is a graph showing a relationship between an incident angle of a light beam on an observation prism of the HMD and a reflectance.

FIG. 3 is a schematic diagram showing a luminance distribution (a) of image light reflected by an observation prism of the HMD, a density distribution (b) of an ND filter, and a luminance distribution (c) of an observation image.

FIG. 4 is a sectional view of an HMD according to a second embodiment of the present invention.

FIG. 5 is a schematic diagram showing a luminance distribution (a) of image light reflected by an observation prism of the HMD according to the second embodiment, a density distribution (b) of an ND filter, and a luminance distribution (c) of an observation image.

FIG. 6 is an external perspective view of a conventional HMD.

FIG. 7 is a sectional view of a conventional HMD.

FIG. 8 is a diagram showing edges of a deposited film seen in a visual field in a conventional HMD.

[Explanation of symbols]

101 HMD 102 Image display element (reflection type LCD) 103 LED 104 Reflecting member 105 Polarizer 106 Illumination prism 107 Emission polarizer 108 Observation prism 109a Region satisfying the total reflection condition (on the second surface of the observation prism) 109b (Observation prism) 110, 130 ND filter 111 Back cover 112 Light-shielding line shape 113 Felt member 701 HMD 702 Image display element 703 Backlight 704 Electric circuit board 705 Prism 709 Mask

Claims (13)

[Claims] 1. An image display comprising: an image display element for displaying an image corresponding to a supplied signal; and a projection optical element for reflecting image light emitted from the image display element and projecting the reflected image light onto an eyeball of an observer. An apparatus, comprising: a first area that satisfies a total reflection condition for image light and a second area that does not satisfy a total reflection condition on a reflection surface of the projection optical element; It has brightness adjustment means for lowering the brightness of the light beam reflected on the first area out of the image light incident on the optical element, than the brightness of the light beam reflected on the second area. An image display device characterized by the above-mentioned. 2. The image display device according to claim 1, wherein said brightness adjusting means is an ND filter. 3. The density of the ND filter ranges from a portion of the image light that transmits light rays reflected by the first region to a portion of the image light that transmits light beams reflected by the second region. The image display device according to claim 2, wherein the image display device changes gradually. 4. The projection optical element includes first, second, and third surfaces, and transmits image light incident from the first surface to the first and second regions on the second surface. 4. The optical element according to claim 1, wherein the optical element sequentially reflects on the third surface and transmits the image light reflected on the third surface through the second surface for emission. An image display device according to claim 1. 5. An illumination light source, an image display element for displaying an image corresponding to a supplied signal to modulate illumination light from the illumination light source, and an image light emitted from the image display element for reflecting the image light. An image display device having a projection optical element for projecting an eyeball of an observer, wherein a reflection area of the projection optical element does not satisfy a first region that satisfies a condition of total reflection of image light and a condition of a total reflection. A second region, wherein, of the illumination light emitted from the illumination light source to the image display element, the luminance of the second light is higher than the luminance of a light beam to be modulated into image light reflected by the first region. An image display device characterized in that the luminance of a light beam that is modulated into image light reflected by the region is reduced. 6. An illumination light emitted from the illumination light source to the image display device in an optical path of the illumination light from the illumination light source to the image display device, to an image light reflected by the first region. 6. A brightness adjusting means for lowering the brightness of a light beam to be modulated by the image light reflected by the second area than the brightness of a light beam to be modulated. Image display device. 7. The image display device according to claim 6, wherein said brightness adjusting means is an ND filter. 8. The density of the ND filter is changed from a portion of the illumination light, which transmits a light beam to be modulated into an image light reflected by the first region, to a portion of the image light reflected by the second region. 8. The image display device according to claim 7, wherein the light intensity is gradually changed to a portion through which a light beam to be modulated passes. 9. The projection optical element includes first, second, and third surfaces, and transmits image light incident from the first surface to the first and second regions on the second surface. 10. The optical element according to claim 5, wherein the optical element sequentially reflects the light on the third surface and transmits the image light reflected on the third surface through the second surface. An image display device according to claim 1. 10. The projection optical element is housed in a housing, and a reflection for preventing light transmitted through the second area of the reflection surface of the projection optical element from being reflected by the inner surface of the housing. The image display device according to claim 1, further comprising a prevention unit. 11. The apparatus according to claim 1, wherein the anti-reflection means has a light-shielding line shape formed on an inner surface of the housing.
0. The image display device according to 0. 12. The image display device according to claim 10, wherein the anti-reflection means is a felt attached to an inner surface of the housing. 13. An image display device according to claim 1, further comprising: an image information supply device that supplies the image display device with image information corresponding to an image to be displayed on the image display element. An image display system comprising: