JPH08184779A - Eye-ball projection type image display device - Google Patents

Abstract

PURPOSE: To provide the eye-ball projection type image display device of a head mounted image display device or the like where the occurrence of aberration is reduced even though a compact optical system is used and color slurring is not caused even though it has a large exit pupil system. CONSTITUTION: As for the eye-ball projection type picture display device having a liquid crystal display device 2 and an eyepiece 3 projecting a displayed image on the retina of an user, a first hologram element 17 and a second hologram element 18 are provided in an optical path between the eyepiece 3 and an exit pupuil 6 formed by the eyepiece 3, and the first hologram element 17 and the second hologram element 18 are constituted so that the angle of diffraction by the second hologram element 18 for respective wavelength of the image may nearly match the angle of the diffraction by the first hologram element 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eyeball projection type image display device for guiding an image as a virtual image into a user's eyeball and observing the image. In particular, the present invention relates to a head-mounted image display device that is attached to the head of an observer and is capable of projecting an image on the retina in the eyeball.

[0002]

2. Description of the Related Art Conventionally, there has been proposed an eyeball projection type image display apparatus in which an image is guided into a user's eyeball as a virtual image and the image can be observed. In particular, wear it on the user's head,
A head that displays an image using an image display device such as an LCD display device or a CRT display device and guides the image to a large screen image as a virtual image in the user's eye by using various eyepiece optical systems such as a lens system and a concave mirror. Part-mounted video display devices are known.
This head-mounted image display device can be mounted on the user's head through the mounting means, and it is not necessary to hold the device with hands, etc., and a large screen is provided by a small image display element provided inside the device body. It is a new type of image display device that allows you to see images.

Such a head-mounted image display device is generally one that magnifies and projects an image displayed on a two-dimensional display element such as a liquid crystal display element onto a user's retina by using an eyepiece optical system. Is. (For example, JP-A-4-170512). However, when the numerical aperture of the eyepiece optical system is large, aberration is likely to occur, and in order to prevent this, there is a problem that the configuration becomes complicated and the optical system becomes a large lens system. Therefore, a head-mounted image display device in which the numerical aperture is controlled on the side of the illumination system has also been proposed (Japanese Patent Laid-Open No. 3-214872).

[0004]

However, when the numerical aperture of the eyepiece lens is small, there is a problem that light rays are likely to be vignetted at the pupil of the user's eye. This problem will be described with reference to FIG. FIG. 11A shows a main part of a conventional head-mounted image display device. The back of the liquid crystal display element 2 is illuminated by the illumination system 1, and a magnified image of the image displayed by the liquid crystal display element 2 is projected onto the retina 5 of the eyeball 4 of the user by the convex lens 3 which is the eyepiece optical system. The illumination system 1 illuminates the liquid crystal display element 2 with a small numerical aperture in order to suppress the aberration of the convex lens 3 to be small. Therefore, the diameter of the exit pupil 6 of this head-mounted image display device is small as shown. If the head-mounted image display device is mounted so that the exit pupil 6 and the pupil position 7 of the user are exactly the same, as shown in the figure, at least when the user is gazing at the center of the image, Since the light rays emitted from the central image P1 and the peripheral image P2 of the liquid crystal display element 2 pass through the pupil 7, the user can observe the image projected by the liquid crystal display element 2 from the center to the periphery. In the figure, P1 'and P2' on the retina 5 are images of images P1 and P2, respectively.

However, if the exit pupil 6 and the user's pupil 7 do not exactly coincide with each other, a light ray is kicked by the pupil 7 and the image is shaded. Further, as shown in FIG. 11 (b), when the user directs his or her eyes on the peripheral image P2, the eyeball 4 rotates around the rotation point near the center of the eyeball, so that the position of the pupil 7 is changed. The rays of light that are displaced and emit the central image P1 and the peripheral image P2 are more difficult to pass through the pupil 7. Then, in an extreme case, the image becomes unobservable.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is an eyeball projection type having a large exit pupil diameter with little aberration while using a compact optical system. An object is to provide a video display device. On the other hand, in order to solve this problem, the applicant proposes that the exit pupil can be enlarged by using two diffractive means in the specification and the drawing of Japanese Patent Application No. 6-41166 which have not been published at the time of filing this application. Therefore, an example in which a diffraction grating is used as the diffraction means is shown. In this method, as shown in FIG. 12A, the first diffraction grating 11 and the second diffraction grating 12 are provided in the optical path between the eyepiece optical system 3 and the exit pupil 6 formed by the eyepiece optical system 3.
Are sequentially arranged along the optical path as shown in the figure, the incident light from the display surface is diffracted into a plurality of lights by the first diffraction grating 11, and these lights are again divided by the second diffraction grating 12. The light beam diameter b of the diffracted light is wider than the light beam diameter a of the incident light, resulting in a large exit pupil diameter.

However, as shown in FIG. 12B, the diffraction angle of the diffraction grating differs depending on the wavelength. R, G, and B represent red, green, and blue rays or luminous fluxes, respectively. Therefore, in this method, the position where the diffraction grating 12 is emitted is different for each color, and the resulting exit pupil is also displaced for each color as shown in FIG. 12C. Therefore, when the user moves the pupil, the color of the observed image changes.

The present invention is an improvement of the invention filed previously, and it is possible to obtain a large exit pupil diameter with little aberration while using a compact optical system, and it is also possible to obtain good color unevenness of the exit pupil. It is a further object to provide an eyeball projection type image display device capable of obtaining an image.

[0009]

In order to solve the above problems, in the configuration of the eyeball projection type image display apparatus of the present invention, the image display means for displaying an image and the light flux emitted from the image display means are condensed. And an eyepiece optical system for forming an exit pupil and forming an image of the image on the retina in the user's eye arranged near the exit pupil, in the eyeball projection type image display device, wherein the eyepiece optical system is In the optical path between the image display means and the exit pupil, there is provided a light beam splitting element and a hologram element, which are sequentially arranged apart from each other along the optical axis.

Further, the image display means is a full-color image display means in which the light flux emitted from the image display means includes the wavelength regions of the three primary colors, and the light beam splitting element divides the incident light beams in the wavelength regions of the three primary colors into a plurality of colors. The hologram element is configured to be split into light beams, and the hologram element suppresses the deviation amount of each plus primary light beam in the direction perpendicular to the optical axis of the split plurality of light beams to 2 mm or less and emits each minus primary light beam. The structure is characterized in that the amount of deviation in the direction perpendicular to the optical axis is suppressed to 2 mm or less, and the light is ejected with almost matching.

Furthermore, the light beam splitting element is a first hologram element. Furthermore, when the first hologram element is the second hologram element, and the primary diffraction angles of the three primary colors by the light beam splitting element are αr, αg, and αb, respectively, the three holograms of the three primary colors by the second hologram element are Each first-order diffraction angle αr ', α
g ', αb' is 0.9 αr <αr '<1.1 αr, 0.9 αg <αg'<
The feature is that 1.1 αg, 0.9 αb <αb '<1.1 αb.

Furthermore, the light beam splitting element is a first hologram element. Furthermore,
The first and second hologram elements each have a strong wavelength selectivity that exhibits the highest diffraction efficiency at different wavelengths and a diffraction efficiency that is less than half of the highest diffraction efficiency at a wavelength within 30 nm of the wavelength exhibiting the highest diffraction efficiency. It is characterized in that it is composed of a plurality of hologram elements.

Further, the plurality of hologram elements are sequentially arranged along the optical axis. Still further, the eyepiece optical system is composed of an eyepiece optical system having power in order from the image display means side, a first hologram element, a second hologram element, and a diopter correction lens. Is.

Further, the eyeball projection type image display device of the present invention is provided with an image display means for displaying an image, a light flux emitted from the image display means to form an exit pupil, and the exit pupil is arranged in the vicinity of the exit pupil. An eyepiece projection type image display device having an eyepiece optical system for forming the image of the image on the retina in the user's eyeball, wherein the eyepiece optical system is in the optical path between the image display means and the exit pupil. And a hologram element and a light flux synthesizing element, which are sequentially arranged apart from each other along the optical axis.

[0015]

According to the invention of claim 1, the image displayed by the image display means can be observed as a virtual image by the eyepiece optical system. At this time, it is necessary to position the user's pupil near the exit pupil formed by the eyepiece optical system and guide the light beam into the eyeball. In this configuration, the incident light flux emitted from the image display means is separated into a plurality of light fluxes by a light flux splitting element such as a diffraction grating or a hologram element, and further, each light flux is separated to a hologram element positioned with air or a transparent medium interposed therebetween. Are shifted in the direction perpendicular to the optical axis and made incident. Then, due to the diffracting action of the hologram element, the direction of the light flux is changed to the observer's eyeball side to form an enlarged exit pupil. At this time, by using the hologram element, it is not necessary to cause unnecessary diffraction in the wavelength range, so that the exit pupil can be efficiently enlarged.

Further, according to the invention of claim 2, the above structure enables the image display device to display three primary colors and to display full color. A light beam including each wavelength region enters a light beam splitting element and is split into a plurality of light beams.
Then, the deviation amount of the ± first-order light beams of the plurality of divided light beams that have entered the hologram element is suppressed to 2 mm or less, and the light beams are substantially matched and emitted. Therefore, the color unevenness of the exit pupil is suppressed, and the color change of the image due to the movement of the observer's pupil position can be suppressed. If the above conditions are not satisfied, color unevenness cannot be ignored. Further, the deviation amount of the ± first order light flux is 1 mm or less,
Further, if it is 0.5 mm or less, color unevenness is further eliminated, which is more preferable.

Further, according to the third aspect of the invention, by using the light beam splitting element as the first hologram element, the position for each wavelength of the light beam incident on the hologram element after the first hologram element has exited. The displacement can be suppressed, the positional restriction of the hologram element can be relaxed, and the hologram element can be miniaturized. Further, according to the invention of claim 4, by satisfying the above condition, the incident angle of the light beam splitting element and the exit angle of the second hologram element in each wavelength region can be made substantially the same. Therefore, a plurality of exit pupils can be formed in the same shape.

Further, according to the invention of claim 5, since the first hologram element and the second hologram element have substantially the same structure, the manufacturing cost can be saved. Further, according to the invention of claim 6, since light is separated for each wavelength and diffracted, light having different diffraction angles (crosstalk light) is eliminated, and observation is facilitated. Further, according to the invention of claim 7, the plurality of hologram elements can be adjusted at the front and rear positions on the optical axis according to the separated state of the light flux in each wavelength range to expand the pupil.

Furthermore, according to the invention of claim 8, a virtual image can be generated at a distance that is easy for an observer to see by inserting a diopter correction lens between the second hologram element and the exit pupil. According to the invention of claim 9, the image displayed by the image display means can be observed as a virtual image by the eyepiece optical system. At this time, it is necessary to position the observer's pupil near the exit pupil formed by the eyepiece optical system and guide the light beam into the eyeball. In this configuration, the incident light flux emitted from the image display means is separated into a plurality of light fluxes by the hologram element, and each of the light flux combining elements such as the diffraction grating and the hologram element, which are spaced apart by sandwiching air or a transparent medium, is used. The luminous flux is shifted in the direction perpendicular to the optical axis and is incident. Then, the light flux combining element combines the light fluxes toward the observer's eyeball side to form an enlarged exit pupil. At this time, by using a hologram element, it is possible to efficiently guide the beam to the beam combining element without causing diffraction in the unnecessary wavelength range, as compared to the above-mentioned one that has not been published at the time of filing and only the diffraction grating is used. Can be achieved.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The eyeball projection type image display device of the present invention will be described below based on several embodiments. FIG. 1 is an example of an eyeball projection type image display device of the present invention, which includes a support portion 13 for mounting the eyeball type projection image display device on the head, and is provided on the crown, the temporal region, and the forehead (not shown). The user's head can be clamped by the user, and the head-mounted image display device 14 is configured as a whole. A left-eye image display unit 15a and a right-eye image display unit 15b corresponding to the respective eyeballs are located in front of the left and right eyes of the user (not shown). Further, the speaker 16 is provided in the vicinity of both ears of the user so that the user can enjoy audio and video at the same time. In each of the embodiments described below, the image display units 15a and 15 at the tip of the head-mounted image display device 14 are provided.
The internal structure of either or both of b is shown. First Embodiment FIG. 2 is a diagram showing a main part of a head-mounted image display device according to a first embodiment. This eye-projection image display device has RGB pixels as image display means in a matrix display surface. The image displayed on the color liquid crystal display element 2 arranged on the screen is projected on the eyeball of the user as a magnified image by the convex lens 3 of the eyepiece optical system, and the liquid crystal display element 2 is arranged behind the illumination system 1
It is illuminated by and the display image is displayed. Then, based on the present invention, the first hologram element 1 is provided between the convex lens 3 of the eyepiece optical system and its exit pupil 6.
7 and the second hologram element 18 are sequentially arranged along the optical axis. The hologram elements here are all transmission type volume holograms. The first hologram element 17 has three hologram elements, each of which is composed of a hologram element for red light diffraction 17r, a hologram element for green light diffraction 17g, and a hologram element for blue light diffraction 17b in the order of optical axes. The second hologram element 18 unit also has three hologram elements, each of which is composed of a red light diffraction hologram element 18r, a green light diffraction hologram element 18g, and a blue light diffraction hologram element 18b in the order of the optical axes. There is. Each hologram element 17r, 17g, 17b and 18r, 18g, 18b
Has a strong wavelength selectivity with respect to R, G, and B light, and specifically, shows the maximum diffraction efficiency at the wavelengths of the R, G, and B regions, respectively, plus or minus the wavelength at which the maximum diffraction efficiency is exhibited. The hologram element has a diffraction efficiency that is less than half the maximum diffraction efficiency at the wavelength of 30 nm. FIG. 3 shows an example of a curve obtained when the wavelength selectivity of the hologram element is set, and the width is substantially centered around the wavelength where the diffraction efficiency is highest (the wavelength satisfying the Bragg condition). Only light of a certain wavelength is regenerated. Then, the refraction angles αr and αr ′ of the first-order diffracted light of red light passing through the hologram elements 17r and 18r for red light, and the refraction angle αg of the first-order diffracted light of green light passing through the hologram elements 17g and 18g for green light diffraction. , αg ′, hologram element for blue light diffraction 17
refraction angle αb of the first-order diffracted light of blue light passing through b and 18b
, αb 'are set to be almost the same (αr = αr' =
αg = αg ′ = αb = αb ′), the distance between the red light diffraction hologram elements 17r and 18r, the distance between the green light diffraction hologram elements 17g and 18g, and the blue light diffraction hologram elements 17b and 18b. The distance and the distance are almost the same. A concave lens 19 for diopter correction is arranged on the side from which the light rays are emitted.

When the first and second hologram elements 17 and 18 are arranged in this way, the parallel light (the optical axis light as a representative thereof is shown in the figure for simplification of the description) transmitted through the convex lens 3 Incident on the hologram element 17 of
Each of the hologram elements for each color diffracts red light only, green light only, and then blue light only in this order to obtain red light R,
Green light G, blue light B plus and minus primary light is αr, α
The light enters the second hologram element 18 with the diffraction angles of g and αb. The rays of light of the respective colors incident on the second hologram element 18 are diffracted at the same diffraction angle as that of the first hologram element 17 to become parallel rays again. At this time, since the light rays of the respective colors are diffracted by the hologram elements 18r and 18g18b where the distances from the optical axis are the same, there is no color shift when the second hologram element 18 is emitted. That is, the amount of pupil misalignment of each color in the direction perpendicular to the exit optical axis of the plus / minus primary light flux at the exit pupil 6 is zero. Regarding the change of the exit pupil diameter at this time, the pupil diameter without the hologram elements 17 and 18 is Φ = 4 mm, and the diffraction angles of the hologram elements 17 and 18 are φ = 3, respectively.
If the distance between the corresponding hologram elements for each color is L = tan (90 ° -φ) × Φ / 2 = 3.5 mm, the exit pupil diameter is doubled to 8 mm. Then, by further passing through the diopter correction concave lens 19, the image is guided to a position that is easy for the user to see. By placing the eyeball 4 near the exit pupil 6, a clear image is guided on the retina 5.

Therefore, even with a display device having a small numerical aperture, a head-mounted image display device having a large exit pupil and no color unevenness can be achieved. Next, a modification of the first embodiment is shown in FIG. FIG. 4 shows only the modified portions of the first hologram element 17 and the second hologram element 18 shown in FIG. 1, and the other configurations are omitted.

The diffraction angles of αr, αg and αb by the hologram elements corresponding to the respective colors in the first hologram element 17 are changed. For each of these diffraction angles αr, αg,
Corresponding to αb, the diffraction angles of the hologram elements corresponding to the respective colors in the second hologram element 18 are αr ′ = αr,
αg '= αg and αb' = αb. Then, the distance between the corresponding hologram elements is set to L = tan so that the exit pupil diameter by the emitted light flux is doubled.
It is arranged according to (90 ° −φ) × φ / 2. Therefore, the order in which the hologram elements for diffracting each color of the first embodiment are arranged is changed. Even with such a configuration, the same effect can be obtained.

FIG. 5 shows another modification of the first embodiment. This is an example in which the optical path combining diffraction grating 12 is used instead of the second hologram element 18. Similarly, only the modified portion is shown, and other configurations are omitted. The diffraction angles of αr, αg, and αb by the hologram elements corresponding to the respective colors in the first hologram element 17 are changed. Corresponding to each of these diffraction angles αr, αg, αb,
The diffraction angles corresponding to the respective colors of the diffraction grating 12 are αr '= αr
, Αg ′ = αg, αb ′ = αb (correctly, the diffraction angle and position of the hologram element 17 are set in accordance with the diffraction efficiency of the diffraction grating 12). Then, the distance between the corresponding hologram element and the diffraction grating is set so that the exit pupil diameter by the emitted light flux is doubled.
It is arranged according to tan (90 ° -φ) × Φ / 2. Therefore, the number of elements for diffracting each color of the first embodiment can be reduced. Even with such a configuration, the same effect can be obtained.

FIG. 6 shows another modification of the first embodiment. This is an example in which the diffraction grating 11 for splitting the optical path is used instead of the first hologram element 18. This also shows only the deformed portion and omits other configurations. According to the diffraction angles of αr, αg, and αb corresponding to the respective colors of the diffraction grating 11, the holograms corresponding to the respective colors in the second hologram element 18 are associated with the respective diffraction angles αr, αg, and αb. The diffraction angles of the element are αr '= αr, αg' = αg
, Αb ′ = αb. Then, the distance between the corresponding diffraction grating and hologram element is set to L = ta so that the exit pupil diameter by the emitted light beam is doubled.
It is arranged according to n (90 ° -φ) × Φ / 2. Therefore, the number of elements for diffracting each color of the first embodiment can be reduced. Even with this structure, the exit pupil can be made large while correcting color unevenness.

In the above example, the exit pupil having no color shift is shown in FIG.
As shown in (a), a method of arranging two vertically or horizontally is shown.
Of course, a plurality of exit pupils may be arranged in the vertical and horizontal directions as shown in FIGS. 7B and 7C, if necessary. A configuration for forming these exit pupils (a), (b), (c) is shown in FIG.
These are shown in (a), (b), and (c), respectively. In order to form the exit pupil as shown in FIG. 7A, as shown so far, a light flux including a hologram element that splits the incident light flux into two in the lateral direction as shown in FIG. 8A. The splitting element 20 and the light flux combining element 21 may be used.

In order to form two four exit pupils vertically and horizontally as shown in FIG. 7 (b), a light beam split including a hologram element for diffracting light into four as shown in FIG. 8 (b). The element 20 or the light flux combining element 21 may be used. Figure 7 (c)
In order to arrange two such six exit pupils vertically and horizontally three, four hologram elements or the like may be used as shown in FIG. 8C. The four are the light beam splitting element 20a and the light beam combining optics 21a that include a hologram element for vertically arranging the exit pupils vertically, and the light beam splitting that includes a hologram element for horizontally arranging the exit pupils three times. The element 20b and the light flux combining element 21b may be used.

The luminous flux combining elements 20 and 2 shown here are used.
0a, 20b and the light beam combining elements 21, 21a, 21b may be hologram elements if any one of the pairs in the optical path as described above is a hologram element for red light diffraction, It is desirable that the hologram element for green light diffraction and the hologram element for blue light diffraction are used. Second Embodiment In this embodiment, as shown in FIG. 9, a reflective color hologram is used instead of the transmission hologram of the first embodiment. Hereinafter, the same numbers are given to the same configurations and the description thereof is omitted.

Reference numerals 22 and 23 in the drawing are reflection type color holograms, and a Lippmann hologram is particularly suitable as this hologram. Here, the reflection type color hologram 22 is a first hologram element for dividing the optical path, and the reflection type color hologram 23 is a first hologram element for guiding the optical path divided by the reflection type color hologram 22 to the eyelid 4 side. The second hologram element.

The image displayed on the color liquid crystal display element 2 in which RGB pixels as image display means are arranged in a matrix on the display surface is projected as a magnified image on the eyeball of the user by the convex lens 3 of the eyepiece optical system. The liquid crystal display element 2 is illuminated by an illumination system 1 arranged behind the liquid crystal display element 2 so that its display image is projected. And based on the present invention,
Reflective color holograms 22 and 23 are sequentially arranged between the convex lens 3 of the eyepiece optical system and its exit pupil (not shown) along the reflection of the optical axis. The hologram elements here are all reflective holograms. The first hologram element 22 has three (three-layer) film-shaped hologram elements, each of which is a reflection hologram element for red light diffraction (film) and a reflection hologram element for green light diffraction (in order of optical axis). Film) and a reflection type hologram element (film) for blue light diffraction, and the second hologram element 23 also has three sheets (three layers).
And a hologram element in the form of a film, the reflection hologram element for red light diffraction (film), the reflection hologram element for green light diffraction (film), and the reflection hologram element for blue light diffraction (film). ). Each reflection hologram element (film) has a strong wavelength selectivity with respect to R, G, B light. Specifically, the maximum diffraction efficiency is obtained at the wavelengths of R, G, B regions. The hologram element has a diffraction efficiency that is half or less of the above-mentioned maximum diffraction efficiency at a wavelength of plus or minus 30 nm of the wavelength showing the maximum diffraction efficiency. Then, the reflection angle of the first-order diffracted light of red light reflected by the reflection hologram element for red light diffraction, the reflection angle of the first-order diffracted light of green light reflected by the reflection hologram element for green light diffraction, the reflection type for blue light diffraction The difference in the angle of reflection of the first-order diffracted light of blue light reflected by the hologram element with respect to each 0th-order reflection direction is set to be substantially the same, and
The surface of each reflection hologram element 22, 23 so that the distance between the reflection hologram elements for red light diffraction, the distance between the hologram elements for green light diffraction, and the distance between the hologram elements for blue light diffraction are made substantially the same. 3 layer device (film)
Is in a state of being worn. A concave lens 19 for diopter correction is arranged on the side from which the light rays are emitted.

When the first and second reflective hologram elements 22 and 23 are arranged in this way, the parallel light transmitted through the convex lens 3 (the optical axis light as a representative thereof is shown in the figure for simplification of the description) first. When it enters the reflective hologram element 22,
In each of the hologram elements for each color, only the red light, only the green light, and then only the blue light are diffracted in that order, and the plus / minus primary light of the red light, the green light, and the blue light respectively have the same diffraction angle, and the reflection hologram element 23. Incident on. The incident light at this time, the reflection positions of the respective colors are substantially the same and the diffraction angles are the same, so that the light beams of the respective colors are almost overlapped to form a light beam having no color shift. The light rays of the respective colors incident on the second reflective hologram element 23 are diffracted at the same diffraction angle as that of the first reflective hologram element 22 to become parallel light again. Therefore, no color shift occurs when the second reflective hologram element 23 is emitted. That is, the amount of pupil misalignment of each color in the direction perpendicular to the exit optical axis of the plus / minus primary light flux at the exit pupil (not shown) is almost zero. Regarding the change of the exit pupil diameter at this time, the pupil diameter when there are no reflection hologram elements 22 and 23 is Φ = 4 m
m, the diffraction angles with respect to the reflection optical axes of the reflection type hologram elements 22 and 23 are φ = 30 °, and the distance between the corresponding hologram elements for each color is L = tan (90 ° −
When φ) × Φ / 2 = 3.5 mm, the exit pupil diameter is almost doubled to 8 mm. Then, by further passing through the diopter correction concave lens 19, the image is guided to a position that is easy for the user to see. By placing the eyeball 4 near the exit pupil (not shown), a clear image is guided on the retina.

Therefore, even with a display device having a small numerical aperture, a head-mounted image display device having a large exit pupil and no color unevenness can be achieved. Further, the reflection type hologram element has an advantage over the transmission type hologram element in that the wavelength selectivity is stronger and a crosstalk image is less likely to occur. Therefore, it is more desirable to use the hologram element described in each claim as a reflection hologram element. Third Embodiment FIG. 10 shows an optical system of a head-mounted image display device using a transmission hologram. The same components as those shown above are designated by the same reference numerals and the description thereof will be omitted. A light bulb 24 as an illumination optical system, a convex lens 25 for illumination, a color liquid crystal display element 2, a concave mirror 26 as an eyepiece optical system, a first hologram element 17, a second hologram element 18 and -1 to-.
Concave lens 19 for diopter correction that can be adjusted with 5 diopters
Are arranged corresponding to the left and right eyeballs 4 of the user, respectively. Light from a miniature electric bulb 24 (point light source) as a low NA illumination system enters a convex illumination lens 25 for parallel illumination, and becomes a substantially parallel light flux and enters the color liquid crystal display element 2.
Then, the light beam is magnified and reflected by the concave mirror 26, enters the first and second hologram elements 17 and 18, and enters the concave lens 19
A light beam is guided to the eyeball 4 via the. Alternatively, the low NA illumination system may be a low NA illumination system including a surface light source and a louver film.

The left and right optical axes are directed inward as a whole, which means that the diopter distance of the concave lens 19 for diopter correction is equal to the convergence distance until the optical axis intersects, as shown in the figure. You can observe the virtual image more naturally. Even with such a configuration, it is possible to achieve a head-mounted image display device that has a large exit pupil and is easy to see without color unevenness even if the display device has a small numerical aperture.

Further, the configurations of the respective embodiments shown above can be replaced with each other as necessary. Further, various modifications may be made within the scope described in the claims.

[0035]

As is apparent from the above description, according to the present invention, it is possible to provide an eyeball projection type image display device having a large exit pupil diameter with a small amount of aberration while using a compact optical system. You can Further, according to the invention of the present application, it is possible to provide an eyeball projection type image display device capable of obtaining a good image without color unevenness of the exit pupil.

[Brief description of drawings]

FIG. 1 is a diagram in which an eyeball projection type image display device of the present invention is applied to a head mounted type image display device.

FIG. 2 is a diagram showing an outline of a first embodiment of the present invention.

FIG. 3 is a diagram showing a characteristic of strong wavelength selectivity.

FIG. 4 is a diagram showing a partially modified example of the first embodiment.

FIG. 5 is a diagram showing an example of a partial modification of the first embodiment.

FIG. 6 is a diagram showing an example of a partial modification of the first embodiment.

FIG. 7 is a diagram showing shapes of various exit pupils according to the present invention.

FIG. 8 is a diagram showing various luminous flux splitting elements and luminous flux combining elements for forming various exit pupils shown in FIG.

FIG. 9 is a diagram showing an outline of a second embodiment of the present invention.

FIG. 10 is a diagram showing an outline of a third embodiment of the present invention.

FIG. 11 is a diagram for explaining a problem when the numerical aperture of the eyepiece lens is small.

FIG. 12 is a diagram for explaining how the pupil is enlarged when two diffraction gratings are used.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Illumination system 2 Liquid crystal display element 3 Convex lens 4 Eyeball 5 Retina 6 Exit pupil 7 Pupil 11 First diffraction grating 12 Second diffraction grating 13 Support part 14 Head-mounted image display device 15a, 15b Image display unit 16 Speaker 17 First hologram element 18 Second hologram element 19 Concave lens 20 Light flux splitting element 21 Light flux combining element 22 Reflective color hologram 23 Reflective color hologram 24 Light bulb 25 Illuminating convex lens 26 Concave mirror

Claims (9)

[Claims] 1. A video display unit for displaying a video image, and a light beam emitted from the video display unit is condensed to form an exit pupil, and the video image is displayed on a retina in a user's eye arranged near the exit pupil. In an eyeball projection type image display device having an eyepiece optical system for forming an image of, the eyepiece optical system is arranged in the optical path between the image display means to the exit pupil in order along the optical axis and spaced apart from each other. An eyeball projection type image display device having a light beam splitting element and a hologram element. 2. The image display means is a full-color image display means in which a light beam emitted from the image display means includes wavelength regions of three primary colors, and the light beam splitting element divides an incident light beam in the wavelength regions of the three primary colors into a plurality of colors. The hologram element is configured to divide the light beam into a plurality of light beams, and the hologram element suppresses the deviation amount of each plus primary light beam in the direction perpendicular to the optical axis of the split plurality of light beams to 2 mm or less and emits each minus primary light beam. 2. The eyeball projection type image display device according to claim 1, wherein the deviation amount in the direction perpendicular to the optical axis is suppressed to 2 mm or less and the light is projected so as to be substantially matched. 3. The eyeball projection type image display device according to claim 1, wherein the light beam splitting element is a first hologram element. 4. When the hologram element according to claim 1 is used as a second hologram element and the primary diffraction angles of the three primary colors by the light beam splitting element are αr, αg and αb, respectively, the second hologram element is used. The first-order diffraction angles αr ′, αg ′, αb ′ of each of the three primary colors are 0.9 αr <αr ′ <1.1 αr, 0.9αg
4. The head-mounted image display device according to claim 1, wherein <αg ′ <1.1 αg, 0.9αb <αb ′ <1.1 αb. 5. The eye projection type image display device according to claim 4, wherein the light beam splitting element is a first hologram element. 6. The first hologram element and the second hologram element each have a maximum diffraction efficiency at different wavelengths, and a diffraction efficiency less than half of the maximum diffraction efficiency at a wavelength of plus or minus 30 nm of the wavelength showing the maximum diffraction efficiency. The eyeball projection type image display device according to claim 3 or 5, wherein the hologram display device comprises a plurality of hologram elements having strong wavelength selectivity. 7. The eyeball projection type image display device according to claim 6, wherein the plurality of hologram elements are sequentially provided along the optical axis. 8. The eyepiece optical system comprises an eyepiece optical system having power in order from the image display means side, a first hologram element, a second hologram element, and a diopter correction lens. The eyeball projection type image display device according to claim 5, 6, or 7. 9. An image display means for displaying an image, a light flux emitted from the image display means is condensed to form an exit pupil, and the exit pupil is formed on a retina in a user's eyeball disposed near the exit pupil. In an eyeball projection type image display device having an eyepiece optical system for forming an image of an image, the eyepiece optical system is arranged in the optical path between the image display means and the exit pupil so as to be sequentially separated along the optical axis. Eye-projection type image display device having a hologram element and a beam combining element.