JPH0965247A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head mounted image display device in which interference between the image display device and face is prevented without making an optical system large in size or complicated. SOLUTION: The device is provided with a two-dimension video display element 1, a relay optical system 2 projecting a real image of the two-dimension video display element 1 into air, an eyepiece optical system 3 projecting the real image into air with magnification and bending an optical axis I1 and a support means supporting the eyepiece optical system 3 so as to be placed just before the eyeball 4 of the user. In this case, the relay optical system 2 and the eyepiece optical system 3 are arranged so that the optical axis I1 is directed toward the eyeball from the inside of the left and right eyeballs of the viewer (toward nose).

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, and more particularly, to a small head- or face-mounted image display device which is held on a user's head or face and projects an image on an eyeball. .

[0002]

2. Description of the Related Art In recent years, a helmet-type or goggle-type image display device held on the head or face has been developed for virtual reality or for the purpose of personally enjoying a large-screen image.

FIG. 7 shows the configuration of the optical system of Japanese Patent Laid-Open No. 5-134208. In this optical system, an image displayed on a two-dimensional image display device 1 such as a liquid crystal display device is projected into the air by a relay optical system 2, and this aerial image (intermediate image) is enlarged by an eyepiece optical system 3 composed of a concave mirror. At the same time, the optical axis is bent and is made incident on the eyeball 4 of the observer.

In this optical system, the concave mirror 3 having a positive power is used.
Is tilted with respect to the optical axis, so that decentering aberration occurs.
Since this decentering aberration cannot be corrected by the coaxial optical system, it is corrected by decentering the relay optical system 2 as shown in the figure.

[0005]

FIG. 5 schematically shows an optical system of such a head-mounted image display device. In the figure, 1 is a two-dimensional image display device, 2 is a relay optical system, 3 is an eyepiece optical system, and 4 is a right eyeball. To avoid interference between the optical system of the head-mounted image display device and the face,
The eyepiece optical system 3 moves away from the front of the face, and the relay optical system 2
Therefore, the two-dimensional image display element 1 needs to be arranged separately on the right side or right side of the face. Hereinafter, the eyepiece optical system 3
As a case where a plane mirror, a concave mirror, and an elliptical concave mirror are used, their problems will be described.

When a flat mirror (for example, a reflection hologram) is used as the eyepiece optical system 3, in order to separate the relay optical system 2 and the two-dimensional image display element 1 from the face, as shown by the solid line in FIG. It is necessary to increase the inclination of 3 to increase the reflection angle α of the eyepiece optical system 3. However, if the inclination of the eyepiece optical system 3 is increased in order to reduce the aberration generated in the eyepiece optical system 3, the inside of the eyepiece optical system 3 (nose side) and the face are likely to interfere with each other.

When a concave mirror is used as the eyepiece optical system In order to avoid interference between the image display element 1 and the relay optical system 2 and the face, an incident optical axis and an outgoing optical axis (concave mirror) to the eyepiece optical system 3 which is a concave mirror are used. Angle α with the optical axis of the reflected ray at
Or it is necessary to increase the distance between the eyeball 4 and the image display element 1. However, each of the above two methods has the following problems.

If the inclination of the ocular concave mirror is increased, the following problems occur. (1) The inside of the concave mirror (nose side) and the face are likely to interfere with each other. (2) The aberration (eccentric aberration) generated by the concave mirror becomes large, and the relay optical system becomes complicated to correct the eccentric aberration. -If the distance between the eyeball and the image display element is increased, the following problems occur. (1) The optical system becomes large. That is, the configuration of the concave mirror
It is impossible to construct an eyepiece optical system that prevents interference between the optical system and the face without increasing the size and complexity of the optical system simply by changing the arrangement.

When an elliptic concave mirror is used as the eyepiece optical system In this case, there are the following two methods for avoiding interference between the image display element 1 and the relay optical system 2 and the face. (1) Increase the distance between the two focal points of the elliptical concave mirror. (2) Increase the tilt angle of the elliptic concave mirror (remove the other focus Q ₂ described below from the face).

However, each of the above two methods has the following problems. Although the case where an elliptical mirror is used as the concave mirror will be described below, the same can be said for the concave mirror in general, such as an approximate ellipse, as well as the following description.

· Increasing the distance between the two focal points of the elliptical concave mirror
Problem in the case of²/ A²+ Y²/ B²= 1 and a> b> 0, the eccentricity e is e = (a²-B²)^1/2/ A. At this time, the coordinates of the two focal points of the ellipse are Q₁(-A
e, 0), Q₂(Ae, 0), focus Q₁Pass through and flat on the Y axis
The coordinates of the intersection P of the straight line and the ellipse are (-ae, b ²/
a). PQ₂And Q₁Q₂Let θ be the angle formed by tan θ = b²/ {2a (a²-B²)^1/2｝

The distance between the two focal points Q ₁ and Q _{2 of the} ellipse (= 2a
To increase e = 2 (a ² −b ² )), either increase a or decrease b. However, in both cases, the point P is brought close to the point Q ₁ and the concave mirror interferes with the face, or the spectacles cannot be used.
Further, if a is increased or b is decreased, the eccentricity of the optical system becomes large (θ becomes small = the angle α becomes large), so that the eccentric aberration of the optical system becomes large.

Further, in order to increase the distance between the two focal points of the ellipse, the radius of curvature of the ellipse may be multiplied by a coefficient (the size of the elliptical mirror is multiplied by a coefficient). The optical system also becomes large.

Problems in Increasing the Inclination Angle of the Elliptical Concave Mirror If the inclination angle of the concave mirror is increased, the position of point Q ₂ moves in the + Y direction. Then, the aberration (eccentric aberration) generated in the eyepiece optical system also becomes large. The eccentric aberration correction complicates the optical system.

That is, it is impossible to construct an eyepiece optical system which prevents interference between the optical system and the face without increasing the size and complexity of the optical system, only by changing the configuration and arrangement of the elliptical concave mirror as in the conventional case. Is.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and its object is a head which prevents interference between the image display device and the face without increasing the size and complexity of the optical system. An object is to provide an optical system for a wearable image display device.

[0017]

An image display apparatus of the present invention which achieves the above object, includes a secondary image display element, a relay optical system for projecting a real image of the two-dimensional image display element in the air.
An image display device comprising an eyepiece optical system for enlarging and projecting the real image in the air and bending the optical axis, and a supporting means for supporting the eyepiece optical system so as to be positioned immediately in front of the eyeball of the user, Is arranged such that the relay optical system and the eyepiece optical system are arranged so as to face the eyes from the inside (nose side) direction of the left and right eyes of the observer.

In this case, the eyepiece optical system may be either a concave reflecting surface or a concave semi-transmissive reflecting surface. Furthermore, it is desirable that the eyepiece optical system satisfy the following condition (1). 15 (mm) <f <40 (mm) (1) where f is the focal length of the eyepiece optical system.

It is more preferable that the eyepiece optical system satisfies the following condition (2). 20 ° <α <80 ° (2) where α is the angle formed by the incident optical axis to the eyepiece optical system and the outgoing optical axis (reflected light beam).

The reason why the above structure is adopted and its function will be described below. FIG. 1 is a diagram for explaining an optical system of a head-mounted image display device according to the present invention. In FIG. 1, 1 is a two-dimensional image display element, 2 is a relay optical system, 3 is an eyepiece optical system, Reference numeral 4 denotes the right eye, and l ₀ : visual axis when observing infinity, l ₁ : principal ray (optical axis) emitted from the display center of the two-dimensional image display element 1, l ₂ : two-dimensional image A principal ray (inner view angle θ ₂ ) emitted from the outside of the display area of the display element 1, and l ₃ : a principal ray (inner view angle θ ₃ ) emitted from the inside of the display area of the two-dimensional image display element 1. .

A light beam emitted from the outside of the two-dimensional image display element 1 (the side far from the face) passes through a portion of the relay optical system 2 far from the face, and once at the eyepiece optical system 3 having a converging / reflecting action. After the reflection, it is directed toward the eyeball 4 from the inner side (nose side) of the eyeball of the observer.

Therefore, the optical axis l ₁ reflected by the eyepiece optical system 3 is seen from the inner side (nose side) of the eyeball 4 of the observer.
Since the relay optical system 2 and the two-dimensional image display element 1 are moved away from the face when facing toward, the interference between the head-mounted image display device and the observer's face does not become a problem, and The flexibility of the layout of the video display device is increased. In this case, the total angle of view (θ ₂ + θ
₃ ) can be immutable.

In an optical system using a concave mirror as the eyepiece optical system 3, the following effects are obtained when the optical axis l ₁ is directed from the inside of the eyeball 4 of the observer toward the eyeball. The eccentric aberration generated in the eyepiece optical system 3 is reduced. Therefore, the eccentric aberration to be corrected by the relay optical system 2 is reduced, so that the eccentric amount of the relay optical system 2 is reduced and the configuration is simplified. Further, since the decrease of the eccentricity of the relay optical system 2 is in the direction in which the relay optical system 2 moves away from the face, the possibility that the relay optical system 2 interferes with the face is further reduced, and the head-mounted image display device The degree of freedom in layout will increase. The concave mirror that constitutes the eyepiece optical system 3 has both a magnifying action of the real image and a bending action of the optical axis, so that the optical system is simplified,
No chromatic aberration occurs.

The focal length f of the eyepiece optical system 3 preferably satisfies the following condition (1). 15 (mm) <f <40 (mm) (1) If the focal length f of the eyepiece optical system is shorter than 15 mm, interference between the eyepiece optical system 3 and the face becomes a problem. Also, the focal length f
Is larger than 40 mm, the eyepiece optical system 3 becomes large and the amount of protrusion from the face also becomes large.

Further, it is desirable that the angle α formed by the incident optical axis to the eyepiece optical system and the outgoing optical axis (reflected light beam) satisfies the following condition (2). 20 ° <α <80 ° (2) The angle α formed by the incident optical axis and the outgoing optical axis in the eyepiece optical system 3 is 8
If it is larger than 0 °, the projection amount of the relay optical system 2 and the two-dimensional image display element 1 becomes large, which is not preferable as a head-mounted image display device. If the angle α is smaller than 20 °, the position where the light beam with the inner angle of view is reflected in the eyepiece optical system 3 is too close to the face, so that interference between the eyepiece optical system 3 and the face becomes a problem.

Further, the visual axes l ₀ and 2 when observing infinity are used.
When the angle formed by the principal ray (optical axis) l ₁ emitted from the display center of the three-dimensional image display element 1 is defined as δ, it is desirable that the angle δ satisfies the following condition (3). 0 ° <δ <40 ° (3) If this angle δ exceeds 40 °, the binocular visible region becomes too narrow, which is not preferable. Further, the virtual image position is too close to the eyeball, which makes it difficult to see the image, which is not preferable. Also,
If δ is smaller than 0 °, observation at infinity cannot be performed, which is not preferable.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments 1 and 2 of an optical system of a head-mounted image display device of the present invention will be described below with reference to the drawings. Example 1 FIG. 2 is a horizontal sectional view of the optical system of Example 1. In FIG. 2, reference numeral 1 is a two-dimensional image display element, 2 is a relay optical system, 10 is a reflection hologram having a concave mirror function which constitutes an eyepiece optical system, and 4 is a right eyeball. In this embodiment, the reflection hologram 10 having the concave mirror action is used as the eyepiece optical system, and the optical axis l ₁ which exits the display center of the two-dimensional image display element ₁ is the eyeball of the observer. Since the relay optical system 2 and the two-dimensional image display element 1 are arranged away from the face, the degree of freedom in layout of the head-mounted image display device is increased. The numerical data of this embodiment is obtained by replacing the elliptic concave mirror 20 of the second embodiment with the reflection hologram 10 having the same function, and the other data is the same, and therefore will be omitted.

[Embodiment 2] A horizontal sectional view of an optical system of Embodiment 2 is shown in FIG. In FIG. 3, 1 is a two-dimensional image display element, 2 is a relay optical system, 20 is an elliptical concave mirror which constitutes an eyepiece optical system, and 4 is a right eyeball. In this example,
The oval concave mirror 20 is used as the eyepiece optical system as described above, and the coaxial system is used as the relay optical system 2. The elliptic concave mirror 20 itself is decentered, and the eccentric aberration due to the decentering is coaxial. The relay optical system 2 is used for correction. Also in this embodiment, as shown in the drawing, the optical axis l ₁ that emits the display center of the two-dimensional image display element 1 is arranged so that the optical axis l ₁ is directed from the inner side of the eyeball 4 of the observer toward the eyeball 4, and the relay optical The system 2 and the two-dimensional image display element 1 can be further separated.

When the XY coordinate system as shown in the figure is taken, the first focus Q ₁ of the elliptic concave mirror 20 is the eyeball 4 on the X axis.
The second focus Q ₂ is located at the center position of the aperture stop located on the X axis between the relay optical system 2 and the eyepiece optical system. In addition, the position (X, Y) of the top of the elliptical concave mirror 20.
Is the position (0, 40.0000) and its elliptic concave mirror 2
The rotationally symmetric aspherical shape of 0 is R is a paraxial radius of curvature, K is a conic coefficient, and h is h ² = X ² + Z ² , the aspherical expression is as follows, and Y = (h ² / R) / K in [1+ {1- (1 + K ) (h 2 / R 2)} 1/2] elliptical concave mirror 20 is K = 0.500000. And T
Is the intersection of the elliptic concave mirror 20 and the X axis on the side of the first focus Q ₁ , the positions (X, Y) of these Q ₁ , Q ₂ and T are as follows.

[0030] Further, the aperture stop, the relay optical system 2, and the two-dimensional image display element 1 constitute a coaxial system, the central axis of which passes through the second focal point Q ₂ and is 29.000000 ° counterclockwise with respect to the Y axis. It makes an angle. The table below shows lens data of the relay optical system 2. In this table, r _i is each surface S _{1 to} S
_The radius of curvature is ₇ , d _i is the surface spacing, and n _i is the refractive index at the d line. Note that d ₀ is the distance between the aperture stop and the first surface S ₁ of the relay optical system 2, and d ₇ is the seventh surface S of the relay optical system 2.
The distance between ₇ and the 2D image display element 1.

[0031]

The angles θ ₂ , θ ₃ , α and δ are
Each is as follows. θ ₂ = 6 °, θ ₃ = 6 °, α = 57.94 °, δ = 4 ° Further, the focal length of the eyepiece optical system 20 + the relay optical system 2 is 5
0.83 mm, the focal length of the relay optical system 2 is 1
The focal length f of the eyepiece optical system 20 is 5.45 mm.
f = 23.01 mm.

By the way, a pair of left and right optical systems according to any one of the above-mentioned embodiments are prepared, and they are supported by being separated by an eye radiation distance, so that a stationary or head-mounted image display device capable of observing with both eyes is provided. It can be configured as such a portable video display device. FIG. 4 shows the overall configuration of an example of such a portable video display device. The display device main body 50 is provided with a pair of left and right display devices according to any one of the above-described embodiments, and a secondary image display element composed of a liquid crystal display element is arranged on the image plane corresponding to these. Body 5
A temporal frame 51 as shown in the figure is provided continuously to the left and right at 0, the temporal frames 51 on both sides are connected by a parietal frame 52, and a leaf spring 53 is provided between the temporal frames 51 on both sides. A rear frame 54 is provided via the rear frame 54, and the rear frame 54 is applied to the rear part of both ears of the observer like a temple of eyeglasses, and the crown frame 52 is placed on the crown of the observer, so that the display device main body 50 is It can be held in front of the observer's eyes. A top pad 55 made of an elastic body such as a sponge is attached inside the top frame 52, and a similar pad is attached inside the rear frame 54 in the same manner. It does not feel uncomfortable when attached to the camera.

The rear frame 54 has a speaker 56.
Is attached, so that you can listen to stereophonic sound while observing images. As described above, the display device main body 50 having the speaker 56 has a video / audio transmission code 57.
The viewer 58 holds the playback device 58 at an arbitrary position such as a belt position as shown in FIG.
You can enjoy the sound. 5 shown
Reference numeral 9 denotes an adjustment unit such as a switch and a volume of the playback device 58. Note that electronic components such as a video processing / audio processing circuit are built in the top frame 52.

The cord 57 may be attached to an existing video deck or the like by using the tip of the cord 57 as a jack. Furthermore, it is connected to a tuner for TV radio wave reception,
It may be used for viewing, or may be connected to a computer to receive computer graphics images, message images from the computer, and the like. Also, in order to reject an obstructive code, an antenna may be connected to receive an external signal by radio waves.

[0036]

As is apparent from the above description, according to the image display device of the present invention, the relay optical system is provided so that the optical axis is directed from the inner (nose side) direction of the left and right eyeballs of the observer to the eyeballs. Since the eyepiece optical system is provided, when used as a head-mounted image display device, the possibility of interference with the face is reduced, and the degree of freedom in the layout of the head-mounted image display device is increased. is there.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an optical system of a head-mounted image display device according to the present invention.

2 is a horizontal sectional view of the optical system of Example 1. FIG.

FIG. 3 is a horizontal sectional view of an optical system of Example 2.

FIG. 4 is a diagram showing the overall configuration of an example of a portable head-mounted image display device according to the present invention.

FIG. 5 is an explanatory diagram of a problem of the conventional head-mounted image display device.

FIG. 6 is an explanatory diagram of a problem when the eyepiece optical system is an elliptical concave mirror.

FIG. 7 is a diagram showing a configuration of an optical system of a conventional head-mounted image display device as an example.

[Explanation of symbols]

l ₀ ... visual axis when observing infinity, l ₁ ... chief ray (optical axis) that exits the display center of the two-dimensional image display element, l ₂ ... exits outside the display area of the two-dimensional image display element Principal ray l ₃ ... Principal ray emitted inside the display area of the two-dimensional image display device θ ₂ ... Inner field angle θ ₃ ... Inner field angle α ... Incident optical axis and exit optical axis to eyepiece optical system (reflected ray)
An angle δ between the visual axis when observing infinity and the principal ray (optical axis) emitted from the display center of the two-dimensional image display element Q ₁ ... First focus Q ₂ ... Second focus S _i ... i-th surface of relay optical system 1 ... two-dimensional image display element 2 ... relay optical system 3 ... eyepiece optical system 4 ... right eye 10 ... reflection hologram (eyepiece optical system) 20 ... elliptical concave mirror (eyepiece optical system) 50 ... Display device main body 51 ... Temporal frame 52 ... Top frame 53 ... Leaf spring 54 ... Rear frame 55 ... Top pad 56 ... Speaker 57 ... Video / audio transmission code 58 ... Playback device 59 ... Control parts for switches, volume, etc.

Claims (3)

[Claims] 1. A secondary image display device, a relay optical system for projecting a real image of the two-dimensional image display device in the air, and an eyepiece optical system for magnifying and projecting the real image in the air and bending an optical axis thereof. In an image display device comprising a supporting means for supporting the eyepiece optical system so as to be positioned immediately in front of the eyeball of the user, the optical axis is directed toward the eyeball from the inside (nose side) direction of the left and right eyeballs of the observer. An image display device comprising the relay optical system and the eyepiece optical system. 2. The image display device according to claim 1, wherein the eyepiece optical system is a concave reflecting surface or a concave semi-transmissive reflecting surface. 3. The image display device according to claim 1, wherein the eyepiece optical system satisfies the following condition (1). 15 (mm) <f <40 (mm) (1) where f is the focal length of the eyepiece optical system.