JPH0974532A - Video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent such a case where an image cannot be partly observed due to the pupil astigmatism by placing an asymmetrical surface in an illumination optical system and then converting the video aspect ratio. SOLUTION: This device is provided with a display element 3, a point light source 1 which illuminates the element 3, an illumination optical system 2' which turns the light emitted from the light source 3 toward the element 3, and an eyepiece optical system 4 which projects the image shown at the element 3 onto the eyeballs of an observer. The system 4 has an asymmetrical surface to secure the different magnification in the vertical and horizontal directions respectively, and the illumination optical system 2' also has an asymmetrical surface. Then the system 4 use an anamorphic lens or a cylindrical lens to secure a long focal distance in the vertical direction compared with the horizontal direction. At the same time, the illumination optical system 2' also uses an anamorphic or cylindrical lens to secure a long focal distance in the vertical direction compared with the horizontal direction.

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, for the purpose of virtual reality or personally enjoying a large screen image,
An image display device that is held on the head or face of a helmet type or goggles type has been developed.

In such a face-mounted image display device, conventionally, the aspect ratio of the screen is 3: 4.
In the method of converting the image displayed on the normal size two-dimensional display element into the wide size image having the aspect ratio of 9:16, optical elements having different focal lengths in the vertical and horizontal directions are used. There is a method in which the magnification in the horizontal direction is made larger than that in the vertical direction, and the image is projected on the observer (Japanese Patent Laid-Open No. Hei.
97671).

When this method is applied to an eyepiece optical system of a face-mounted image display device FMD as shown in FIG. 8, a liquid crystal display element having a normal size image display range (hereinafter referred to as L
Call it CD. In order to project the image displayed in) as a horizontally long image on the eyeball of the wearer M, the horizontal focal length f _2h is f _2h <with respect to the vertical focal length f _2v of the eyepiece optical system. It is necessary to satisfy the relationship of f _2v (1). In particular, in order to project an image displayed on the LCD having an image display range of 3: 4 aspect ratio on the eyeball as an image of 9:16 aspect ratio, f _{2h ≈3} / 4/4 f _2v ... It is advisable to use a cylindrical lens or an anamorphic lens so as to satisfy (2).

At this time, when the LCD is illuminated with a surface light source,
Since the pupil diameter is not so small as to be negligible compared with the aperture diameter of the optical element, there is a drawback that astigmatism occurs and an image becomes difficult to see. In order to solve this, by using the point light source 1 and the collimator lens 2 in the illumination system, as shown in the optical path in FIG. 9,
There is a method of removing the influence of aberration.

[0006]

However, when the point light source 1 and the collimator lens 2 are used in the illumination system as shown in FIG. 9, as shown in the drawing, the horizontal direction is different from the vertical focal length of the eyepiece optical system 4. Since the focal length of is shortened, the chief ray emitted from each point in the lateral direction of the screen of the LCD 3 through the optical axis is refracted by the eyepiece optical system 4 and intersects with the optical axis (horizontal pupil position) E _h . The point (vertical pupil position) E _{v at} which the chief ray emitted from each point in the vertical direction of the screen of the LCD 3 through the axis is refracted by the eyepiece optical system 4 and intersects the optical axis is different, and the vertical pupil position E _v is horizontal. The position is closer to the eyeball than the pupil position E in the direction.

If the deviation of the pupil position is large, as shown in FIG. 10, when the pupil is aligned with the lateral pupil position E _h (FIG. (A)), the light rays outside the vertical luminous flux are the pupil. Cannot pass through (Fig. (B)). Therefore, when the image shown in FIG. 11A is observed, some of the upper and lower images cannot be observed as shown in FIG. 11B. Similarly, when the pupil is aligned with the vertical pupil position E _v , FIG.
As shown in, part of the left and right images cannot be observed.

The present invention has been made in view of the above problems of the prior art, and its object is to use an optical system having different longitudinal and lateral magnifications as an eyepiece optical system in order to convert the aspect ratio of the screen of the display device. In a video display device such as a face-mounted video display device, it is possible to prevent a part of the video from becoming unobservable due to astigmatism of the pupil, and to make it possible to observe the entire screen.

[0009]

An image display apparatus of the present invention which achieves the above object, comprises a two-dimensional display element, a light source for illuminating the two-dimensional display element, and light from the light source for the two-dimensional display element. In an image display device including an illumination optical system directed to a display element, and an eyepiece optical system for projecting an image displayed on the two-dimensional display element onto an observer's eyeball, the eyepiece optical system includes a vertical direction and a horizontal direction. In at least one surface having a rotationally asymmetric surface so that the magnification is different, the light source is a point light source, and the illumination optical system has at least one surface having a rotationally asymmetric surface.

In this case, the eyepiece optical system is composed of a lens,
It is desirable to include a rotationally asymmetric surface in at least one surface. More specifically, the rotationally asymmetric surface can be a cylindrical surface or an anamorphic surface.

In the present invention described above, since at least one rotationally asymmetric surface is arranged in the illumination optical system to convert the aspect ratio of the image, the pupil generated in the rotationally asymmetric surface arranged in the eyepiece optical system is converted. Astigmatism can be removed,
It is possible to prevent a part of the image from becoming unobservable due to this aberration, to observe the entire screen, and to prevent astigmatism from being generated in the observed image.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The principle and some embodiments of a video display device of the present invention will be described below with reference to the drawings. The image display device of the present invention uses an anamorphic lens or a cylindrical lens as the eyepiece optical system 4 as shown in the optical path in FIG. 1 so that the vertical focal length is longer than the horizontal focal length. The point light source 1 is used as the illumination light source, and the anamorphic lens or the cylindrical lens is used for the illumination optical system 2 ′ so that the focal length in the vertical direction is shorter than the focal length in the horizontal direction.

By using an anamorphic lens or a cylindrical lens as the illuminating optical system 2 ', the lateral focal length of the illuminating optical system 2'is made longer than the longitudinal focal length so that the illuminating optical system 2'is Eyepiece optical system 4
The conjugate position of the point light source 1 can be set so as to match in the horizontal direction and the vertical direction as shown by the solid line in FIG. The dotted line in FIG. 1 shows the case where the illumination optical system 2'is configured by a rotationally symmetric optical system as shown in FIG.

This will be described with reference to the explanatory view of FIG. 2. Considering the illumination optical system 2'and the eyepiece optical system 4 as thin lenses, the distance between the point light source 1 and the illumination optical system 2'is d ₁ , and the illumination is performed. The distance between the optical system 2 ′ and the eyepiece optical system 4 is d ₂ , the distance between the eyepiece optical system 4 and the pupil E is d ₃ , and the distance to the conjugate position of the point light source 1 by the illumination optical system 2 ′ and the illumination optical system 2 ′ is t, the focal length of the illumination optical system 2 ′ is f ₁ , and the focal length of the eyepiece optical system 4 is f _{2
When, d 3 = f 2 (d} 2 -t) / {f 2 + (d 2 -t)} ··· (3) t = f 1 d 1 / (f 1 + d 1) ··· (4 ) Is satisfied. (3), (4) _{than, d 3 = [f 2 {} d 2 -f 1 d 1 / (f 1 + d 1)}] ÷ [f 2 + {d 2 -f 1 d 1 / (f 1 + D ₁ )}] = (f ₁ f ₂ d ₂ + f ₂ d ₁ d ₂ −f ₁ f ₁ d ₁ ) ÷ (f ₁ f ₂ + f ₁ d ₂ + f ₂ d ₁ + d ₁ d ₂ −f ₁ d ₁ ) (5) Here, as shown in FIG. 1, when an anamorphic lens or a cylindrical lens is used as the illumination optical system 2 ′ and the eyepiece optical system 4, t, d ₃ and f ₁ , f ₂
Has different values in the vertical and horizontal directions.

In the above equation (5), if the vertical and horizontal values of f ₁ are set so that d ₃ is the same in the vertical and horizontal directions, the conjugate position of the point light source 1 is set in the horizontal and vertical directions. The position of the pupil E can be matched with the position of the pupil E, and the entire surface of the image can be observed by positioning the pupil at the position of the matched pupil E.

Next, an embodiment in which the principle of the present invention is applied to some types of optical systems of a face-mounted image display device will be described. Example 1 FIG. 3 shows an optical system of Example 1. The optical system of this image display device is an LC used as a two-dimensional display element.
D3, a point light source 1 for illuminating the LCD 3 from the back, an illumination optical system 2 ′ including a cylindrical lens or an anamorphic lens on at least one surface, and directing the light from the point light source 1 to the LCD 3, and an LCD 3 At least 1 for projecting the image displayed on the viewer's eye A
The image display device is coaxially provided with an eyepiece optical system 4 including a cylindrical lens or an anamorphic lens on its surface. In the figure, the dotted line indicates the horizontal optical path, and the solid line indicates the vertical optical path.

The eyepiece optical system 4 includes a cylindrical lens or an anamorphic lens so that the lateral focal length is shorter than the longitudinal focal length, so that the lateral magnifying power increases. To make it bigger.

Thus, it is possible to project an image having an aspect ratio of 9:16 on the eyeball A by using the LCD 3 having an aspect ratio of 3: 4.

The point light source 1 is used as a light source for illuminating the LCD 3, and the illumination optical system 2'includes a cylindrical lens or an anamorphic lens on at least one surface, so that an astigmatism is observed in the observed image. Does not occur,
Moreover, astigmatism is not generated in the pupil.

Example 2 FIG. 4 shows an optical system of Example 2. In the optical system of this image display device, the illumination optical system 2 ′ in the first embodiment is replaced with the reflecting mirror 20. And
The shape of the reflecting mirror 20 is an anamorphic surface,
The operation is similar to that of the illumination optical system 2'of the first embodiment. That is, the LCD 3 used as a two-dimensional display element
And a point light source 1 for illuminating the LCD 3 from behind.
And a reflecting mirror 20 composed of an anamorphic surface as an illumination optical system 2 ′ for directing the light from the point light source 1 to the LCD 3.
And an eyepiece optical system 4 coaxially including a cylindrical lens or an anamorphic lens on at least one surface for projecting an image displayed on the LCD 3 onto the observer's eyeball A. The operation of the optical system is similar to that of the first embodiment. In the figure, the dotted line indicates the horizontal optical path, and the solid line indicates the vertical optical path.

[Third Embodiment] FIG. 5 shows an optical system according to a third embodiment. In this example, the eyepiece optical system 4 in Example 1 is
The LCD 3 is composed of a beam splitter 41 that is inclined with respect to the central axis of the LCD 3 and an anamorphic reflection surface 42 that is arranged on the transmission or reflection side (transmission side in the case) of the light beam by the beam splitter 41. Eyepiece optical system 40
Is replaced with. The anamorphic reflection surface 42 acts to convert the aspect ratio of the image. That is, in this eyepiece optical system 40, the light from the LCD 3 is transmitted or reflected (transmitted in the case of the figure) through the beam splitter 41, and the reflected light converted into the converged light by the anamorphic reflection surface 42 is now a beam. The image that is reflected or transmitted (reflected in the case shown) by the splitter 41 and is displayed on the LCD 3 is projected on the observer's eyeball A by increasing the magnification in the horizontal direction with respect to the magnification in the vertical direction.

Also in this embodiment, as in the first embodiment,
The point light source 1 is used as a light source for illuminating the LCD 3, and the illumination optical system 2'includes a cylindrical lens or an anamorphic lens on at least one surface so that astigmatism does not occur in an observed image, and , Astigmatism is not generated in the pupil. In the figure, the dotted line indicates the horizontal optical path and the solid line indicates the vertical optical path. However, since the entire optical system is not coaxial, the vertical optical path actually passes through a cross section perpendicular to the drawing.

[Embodiment 4] FIG. 6 shows an optical system of Embodiment 4. In this embodiment, the eyepiece optical system 4 in the first embodiment is replaced with a decentered reflecting mirror 43. The eccentric reflecting mirror 43 is an anamorphic reflecting surface and has a function of converting the aspect ratio of an image. The operation of the optical system is similar to that of the first embodiment. In the figure, the dotted line indicates the horizontal optical path and the solid line indicates the vertical optical path. However, since the entire optical system is not coaxial, the vertical optical path actually passes through a cross section perpendicular to the drawing.

[Fifth Embodiment] FIG. 7 shows an optical system of a fifth embodiment. In this embodiment, the eyepiece optical system 4 in the second embodiment is replaced with a decentered reflecting mirror 43. The eccentric reflecting mirror 43 is an anamorphic reflecting surface and has a function of converting the aspect ratio of an image. The operation of the optical system is similar to that of the second embodiment. In the figure, the dotted line indicates the horizontal optical path and the solid line indicates the vertical optical path. However, since the entire optical system is not coaxial, the vertical optical path actually passes through a cross section perpendicular to the drawing.

The optical systems of Examples 1 to 5 described above are, for example, as shown in a perspective view in FIG. 8, left and right of a face-mounted image display device FMD which is attached to the face of an observer M and used for image observation. Can be used for the eyepiece optical system.

The above-described video display device of the present invention can be configured as follows, for example.

[1] Two-dimensional display element, light source for illuminating the two-dimensional display element, illumination optical system for directing light from the light source to the two-dimensional display element, and display on the two-dimensional display element In an image display device including an eyepiece optical system for projecting an image to be observed on an observer's eyeball, the eyepiece optical system has at least one rotationally asymmetric surface so that the magnification is different in the vertical direction and the horizontal direction. The image display device is characterized in that the light source is a point light source and the illumination optical system has at least one rotationally asymmetric surface.

[2] The image display device according to the above [1], wherein the eyepiece optical system is composed of a lens and at least one surface includes a rotationally asymmetric surface.

[3] The image display device according to the above [2], wherein the rotationally asymmetric surface is a cylindrical surface or an anamorphic surface.

[4] The eyepiece optical system includes a beam splitter arranged to be inclined with respect to the central axis of the two-dimensional display element, and anamorphic reflection arranged on the transmission or reflection side of the light beam by the beam splitter. The image display device according to the above [1], characterized in that

[5] The image display device according to the above [1], wherein the eyepiece optical system is composed of a magnifying reflecting mirror, and the magnifying reflecting mirror has a rotationally asymmetric surface.

[6] The image display device according to the above [1], wherein the illumination optical system is composed of a lens, and at least one surface thereof includes a rotationally asymmetric surface.

[7] The image display device according to [1], wherein the illumination optical system is composed of a reflecting mirror having a rotationally asymmetric surface.

[8] The horizontal magnification of the eyepiece optics is larger than the vertical magnification, and the vertical focal length of the illumination optical system is shorter than the horizontal focal length. 1] The image display device as described above.

[0035]

As is apparent from the above description, according to the image display device of the present invention, at least one element is provided in the illumination optical system.
By arranging the rotationally asymmetric surface to convert the aspect ratio of the image, it is possible to eliminate the astigmatism of the pupil that occurs in the rotationally asymmetric surface arranged in the eyepiece optical system. It is possible to prevent a part of the image from becoming unobservable and to observe the entire surface of the screen, and the astigmatism does not occur in the observed image.

[Brief description of drawings]

FIG. 1 is a diagram showing an optical path in a basic configuration of an image display device of the present invention.

2 is an explanatory diagram of the configuration of FIG. 1. FIG.

FIG. 3 is a diagram showing an optical system of the image display device of Example 1.

FIG. 4 is a diagram showing an optical system of an image display device of Example 2.

FIG. 5 is a diagram showing an optical system of an image display device of Example 3.

FIG. 6 is a diagram showing an optical system of an image display device of Example 4.

FIG. 7 is a diagram showing an optical system of an image display device of Example 5.

FIG. 8 is a perspective view of a face-mounted image display device to which the optical system according to the present invention is applied.

FIG. 9 is a diagram showing an optical path of a conventional image display device according to one proposal.

10 is a diagram showing that a part of an image cannot be observed in the configuration of FIG.

FIG. 11 is a diagram showing a display image and an observation image in the configuration of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Point light source 2 '... Illumination optical system 3 ... LCD 4 ... Eyepiece optical system 20 ... Reflector 40 ... Eyepiece optical system 41 ... Beam splitter 42 ... Anamorphic reflection surface 43 ... Eccentric reflector E ... Pupil A ... Eyeball M ... Observer (wearer) FMD ... Face-mounted image display device

Claims (3)

[Claims] 1. A two-dimensional display element, a light source for illuminating the two-dimensional display element, an illumination optical system for directing light from the light source to the two-dimensional display element, and a display on the two-dimensional display element. In an image display device including an eyepiece optical system for projecting an image to be observed on an observer's eyeball, the eyepiece optical system has at least one rotationally asymmetric surface so that the magnification is different in the vertical direction and the horizontal direction. The image display device, wherein the light source is a point light source, and the illumination optical system has at least one rotationally asymmetric surface. 2. The image display device according to claim 1, wherein the eyepiece optical system is composed of a lens, and at least one surface thereof includes a rotationally asymmetric surface. 3. The image display device according to claim 2, wherein the rotationally asymmetric surface is a cylindrical surface or an anamorphic surface.