JP2004078241A - Display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make picture quality of a display excellent and to attain miniaturization and weight reduction in a head-up display by which video picture can be observed after attaching to a head in a goggle form or a headgear form. <P>SOLUTION: In an apparatus which has a catoptric system for guiding an original picture displayed on an indicator 12 to eye-balls and which makes the original picture observable, the catoptric system has a reflecting surface R4 having different power according to an azimuth direction and a refraction surface R3 which adjoins the original picture without via another member and which has different power according to the azimuth direction. Both the reflecting surface R4 and the refraction surface R3 are made to have shapes having aspherical action in a plane crossing the original picture, the reflecting surface, the refraction surface and eye-balls. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a head-up display and a display device suitable for a helmet display, a glasses-type display, and a virtual reality display, and particularly to a compact reflective optical system.

Conventional head-up displays include many patent documents, many of which relate to helmets for aircraft. First, as in Patent Document 1, a primary imaging type in which an image on a CRT or the like is formed once through a lens system. The second is a virtual image type in which light is guided from an image to an eyeball to form a virtual image without forming light from an image as in Patent Literature 2. This patent also makes the power of the reflecting mirror of the reflecting optical system slightly stronger, removes the convex lens that magnifies the image, which is generally placed just before the eyeball, and furthermore, reflects the CRT screen so that it tilts toward the human head. The mirror and CRT are set for compactness. The third type is a prism type using a prism to make the reflection optical system compact, as in Patent Document 3. Patent Document 4 discloses a primary image forming type using a prism, and Patent Document 5 describes a virtual image type using a prism.

When a small and light structure such as a goggle-type display is required, the above-mentioned primary imaging type has good optical performance, but requires a large number of lenses and is large, and the prism type is compact. It becomes heavy but becomes heavy. Therefore, the virtual image type is preferable in terms of small size and light weight, but the optical performance is not so good. In this regard, Patent Document 2 described above obtains good optical performance by using the reflecting surface of the reflecting optical system as a toric surface and using the original image surface itself as a toric surface. However, a flat image surface such as a CRT must be converted to a toric surface by glass fiber or the like, which is technically difficult and costly. Further, in the embodiment, the distance IP from the final surface to the eye point is 60 mm or more, which is one of the causes of preventing compactness.

In the present application, as shown in FIG. 2 described later, the eye point is defined as the point at which the center light beam intersects the optical axis of the eye among the maximum image height light beams in the long side direction of the image. The distance from the final effective plane to the eye point on the optical axis of the eye is defined as IP. The final effective surface does not include the glass of the dustproof window.
U.S. Pat. No. 3,940,204 U.S. Pat. No. 4,026,641 U.S. Pat. No. 4,969,724 U.S. Pat. No. 4,589,030 U.S. Pat. No. 4,081,209

An object of the present invention is to provide a display device which is small and light enough to be mounted on the head and has good image performance.

In order to solve the above-mentioned problem, the present invention has a reflection optical system for guiding an original image to an eyeball, and in a device that enables the observation of the original image, the power of the reflection optical system varies depending on the direction of azimuth. Reflecting surface, adjacent to the original image without intervening other members, having a refracting surface having different power depending on the direction of the azimuth, the reflecting surface and the refracting surface together, the original image, the reflecting surface, the refracting surface, and The shape has an aspherical action in the plane intersecting the eyeball.

It should be noted that this apparatus generally converts an original image as a flat reference plane into a virtual image via a reflection optical system, and the reflection plane in the apparatus has power and corrects the image immediately before the eyes. It is not necessary to provide a lens. On the other hand, from another viewpoint, in an apparatus that guides an original image to an eyeball through a reflective optical system and enables observation, one or more members having different power depending on the azimuth direction are provided in the reflective optical system, and An original image is formed such that an image obtained through the reflection optical system does not cause distortion. Further, it is desirable to consider the following configuration.

That is, in the image center luminous flux guided to the eye, the angle θ between the incident central ray of the reflecting member immediately before the eyeball and the exit ray is desirably set to 10 ° or more and 80 ° or less, thereby providing a cathode ray for providing an original image. This is effective for bringing a tube (CRT) or a liquid crystal display (LCD) closer to the human head and making it compact.
10 ° ≦ θ ≦ 80 ° (1)

At this time, since the reflecting mirror has power, as θ becomes larger, eccentric aberration (especially eccentric astigmatism and eccentric field curvature) occurs. In order to reduce this eccentric aberration, a member having a different power depending on the azimuth direction, such as a toric surface, is used for the reflection surface. FIG. 1 is an explanatory diagram of the toric surface, and the radius of curvature differs depending on the azimuth angle ω (0 ≦ ω ≦ 180 °).

Also, in the case of a compact goggle type display, even for a person wearing glasses, the above-mentioned IP distance of 50 mm is sufficient. Therefore, if the IP is set to 50 mm or less, not only the size can be reduced, but also the off-axis light beam is reflected near the periphery of the reflector as compared with the center light beam as in Patent Document 2, whereas the off-axis light beam is considerably reflected by the reflector. Is reflected in the vicinity of the center, the occurrence of the eccentric aberration described above can be reduced.
5 mm ≦ IP ≦ 50 mm (2)
Is preferably satisfied.

If the original image is corrected to the shape shown in FIG. 7 so that the eccentric distortion generated in the reflective optical system is canceled on the image, the eccentric distortion can be free in the reflective optical system. For this reason, the number of lenses in the reflection optical system can be reduced, the size can be reduced, and even if a virtual image is created by enlarging and projecting a plane image, distortion and various aberrations can be reduced. Further, by providing the reflecting mirror with an aspheric surface effect in at least one cross section in the azimuth direction, the above-described eccentric aberration can be reduced. FIG. 8 shows the shape of the screen to be observed. The shape shown in FIG. 7 may be produced by arranging each pixel so that the display surface itself of the liquid crystal display reflects this shape, or may be subjected to electrical processing to a video signal to give distortion. Can be adopted.

As described above, the distance IP from the final optical surface of the optical system to the eye point is set short, and a toric aspherical surface (a surface that has been made aspherical with the toric surface as the basic surface) is used for image correction from the original image. As a result, good performance could be obtained even when a flat original image was projected without using a conversion element such as glass fiber.

As for the lower limit of the conditional expression (1), if the value of the conditional expression (1) is smaller than 10 °, the portion of the original image (LCD, CRT) must be set to a considerably large value of IP unless the value of IP is set to a considerably large value. It hits a human face and becomes larger. On the other hand, if the upper limit exceeds this value, eccentric aberrations will occur too much, and if this is to be corrected, the size will also increase.

If the lower limit of conditional expression (2) is below this value, the image will not be visible at all when the eye is placed at a general observation position (IP 20 mm). The upper limit is as described above. On the other hand, when the original image, the reflecting member, and the eyeball are optically in the same plane with respect to the reflecting member immediately before the eyeball, the power in the azimuth direction is ψ0, and the power in the azimuth direction in a plane perpendicular to the plane is ψ90.
0.3 <$ 0 / $ 90 <1.2 (3)
It is desirable to satisfy the following condition. Here, the power is the reciprocal of the focal length. If the lower limit of conditional expression (3) is exceeded, Δ90 increases, the ray in the azimuth direction of Δ90 becomes under, and the negative diopter becomes too strong. Conversely, when the value exceeds the upper limit, ψ0 increases, and the occurrence of eccentric coma increases in the rays in the azimuth direction of ψ0.

Furthermore, it is preferable to provide a field lens between the original image and the reflection member, which helps to reduce the size of the image. In particular, adopting a toric aspherical surface as the refracting surface of the field lens is effective for improving the optical performance, and can particularly reduce the astigmatic difference.

は In this example described later, an independent reflection optical system is mainly used for the left eye and the right eye. U.S. Pat. No. 5,060,072, U.S. Pat. No. 5,500,544, and the like, have a left / right shared reflective optical system that defines a common reflective surface for the left and right eyes and forms an image. The common reflecting surface has only one surface vertex of the reflecting surface. As is well known, when light is transmitted or reflected at a portion distant from the vertex of the surface, a high-order aberration is largely generated. Therefore, when the left-eye optical path and the right-eye optical path use one reflection vertex with a single surface vertex, both optical paths must be reflected at portions that are far away from the surface vertex, and high-order aberrations are greatly generated. Therefore, the angle of view of the image is reduced. Or, disadvantages such as an increase in size are likely to occur.

Therefore, in this embodiment, the reflection optical system for the left eye and the right eye is independent, and the members in the reflection optical system have mutually independent surface vertices for the left eye and the right eye. By doing so, the portion near the vertex of the surface is used as an optical path, and a high-order aberration is suppressed and a compact image with a high angle of view can be achieved. In addition, the members for the left eye and the right eye are connected, and even if it is one member, it always has an independent surface vertex for the left eye and the right eye. The same applies to the case of using a monocular.

According to the present invention, a remarkably small and lightweight device can be realized, and there is an effect that an image of good image quality can be observed. In addition, since the device is small and lightweight, the feeling of oppression is reduced even when the device is mounted on the head or the like, and the effect of not impairing the freedom of gesture is derived.

First, the toric reflection surface related to the embodiment will be described with reference to FIG.

The symbol # 10 is a toric convex reflecting surface, with the X axis as the optical axis, a sagittal line on the XZ plane and a ψ0 direction, and a generatrix on the XY plane with a ψ90 direction. When the sagittal line is an aspherical surface, the defining equation of the sagittal aspherical surface is

And
As an example of the aspheric coefficients B and C,
−1.0 <B <1.0 (a)
−1.0 <C <1.0 (b)
That is, neither B nor C becomes O. If the lower limit of the expressions (a) and (b) is exceeded, the aspheric action of the negative lens will be too strong, and if the upper limit is exceeded, the aspheric action of the positive lens will be too strong. Further, with respect to the aspherical shape near the surface vertex, the decentering coma generated in the reflection optical system can be improved by forming the aspherical shape in a direction in which the power at the surface vertex is further increased as the distance from the surface vertex increases.

FIG. 2 schematically illustrates the goggle type display device for the right eye from above. However, members for mounting the device on the head are not shown, but a band type, a vine for glasses, a headgear type, or the like can be used. The left eye has a substantially symmetric configuration. In this example, a 1-inch original image is projected 1 m ahead (-1 diopter) to view as a large screen image (virtual image) of about 29 inches, and the angle of view is equivalent to a lens with a focal length of about 50 mm. is there.

In FIG. 2, reference numeral 11 denotes an illumination unit, which comprises a light source 11a, a parabolic mirror 11b, and a condenser lens 11b. Reference numeral 12 denotes a liquid crystal display for providing an original image, which is illuminated from the back by an illumination unit 11. However, when 12 is a small cathode ray tube, an illumination unit is unnecessary.

# 13 is a reflecting member which will be described in detail later, and has a toric convex reflecting surface inside. P is the eye point of the observer, and IP is the distance between the final surface of the reflecting member and the eye point on the optical axis of the eyeball looking at infinity.

Although the reflecting surface of the reflecting member 13 uses a toric aspherical surface, it is preferable to provide the above-mentioned aspherical surface in the azimuth direction cross section when the original surface image and the reflecting member and the eyeball are on the same plane. The reason is that the azimuth direction (the direction of ψ0) generates more aberrations, especially eccentric aberration, than the azimuth direction (the ψ90 direction) orthogonal to this direction.

実 施 Hereinafter, examples in which numerical data are described in a table will be described.

These embodiments use various methods to control eccentric aberration. 3 corresponds to Table 1, FIG. 4 corresponds to Table 2, FIG. 5 corresponds to Table 3, and FIG. FIGS. 3, 4, and 6 show a type in which an original image is arranged on the side of the cheek, and a type in which the original image is arranged in front of the forehead in FIG.

In FIG. 3, a reflecting member 13 having a toric reflecting surface or a toric reflecting aspherical surface and a field lens 14 having a toric lens surface or a toric aspherical surface adjacent to the display 12 are deflected parallel to the cross-sectional view (ψ0 direction). It is cored. X13 is the optical axis of the reflection member 13, and X14 is the optical axis of the field lens 14. Further, the eccentric aberration can be reduced by tilting (tilting) the field lens 14 and the original image plane 12. The reflection surface is formed of a half mirror or the like, and both reflection and transmission are performed.

FIG. 5 also shows an example in which a field lens 14 that is decentered in parallel is provided. The reflection member 13 is a plane parallel plate, which is inclined by 35 degrees with respect to the optical axis of the eyeball, and the intermediate surface R5 is a toric reflection surface or a toric reflection aspheric surface, and is sandwiched between two glasses.

In FIG. 6, (A) is a form viewed from the side, (B) is a form viewed from above, and (C) is an enlarged perspective view of a part of the reflecting member, and a fine reflecting surface is shown. It is a three-dimensionally set angle, and it becomes a holographic plate at the limit. The reflecting member 13 can be placed perpendicular to the optical axis of the eyeball. At this time, if the reflection member 13 is a female type, if the transparent member corresponding to the male type is joined to form a parallel flat plate, there is an advantage that the transmitted light does not cause any distortion at the time of transmission use.

The reflection member 13 shown in FIGS. 3 and 4 described above has the same toric surface or toric aspheric surface as the transmission surface on the back side of the reflection surface on the eyeball side. The aberration of the optical system is good, and the weight can be reduced.

FIGS. 3, 4 and 6 show a type in which a light beam is bent in a horizontal direction by a reflection member. FIG. 5 shows a type in which a light beam is bent in a vertical direction by a reflection member. The image formed by the reflection optical system of the embodiment is longer in the horizontal direction than in the vertical direction. That is, since the image is a rectangular image having a long side in the left-right direction and a short side in the up-down direction, the type in which the light beam is bent in the vertical direction as in the example of FIG. The optical system itself can be made thinner than a horizontal bending type (FIGS. 3, 4, and 6).

Also, the ψ0 direction tends to generate more aberration than the ψ90 direction. The horizontal bending type shown in FIGS. 3, 4, and 6 is a light ray in the long side direction having a large angle of view in the ψ0 direction, whereas the vertical bending type in FIG. 5 is a short side direction having a small angle of view in the ψ0 direction. In the case of the vertical bending type, which is a ray of light, less aberration occurs and better performance can be obtained.

The present invention can be applied to a primary imaging type of a head-up display.

FIG. 3 is a perspective view for explaining a toric reflection surface. FIG. 2 is a plan view showing the arrangement of the embodiment of the present invention. The top view which shows another Example of this invention. The top view which shows another Example of this invention. FIG. 6 is an elevation view showing another embodiment of the present invention. FIG. 11 is a plan view showing still another embodiment of the present invention. The figure which shows an original image. The figure which shows an observation image.

Explanation of reference numerals

12 Display of original image 13 Reflective member 14 Field lens P Eye point

Claims (5)

In a device having a reflection optical system for guiding an original image to an eyeball and enabling observation of the original image, the reflection optical system includes a reflection surface having different power depending on the azimuth direction and the original surface without passing through another member. A refracting surface adjacent to the image, the power of which varies depending on the direction of the azimuth, wherein the reflecting surface and the refracting surface are both aspheric in a plane intersecting the original image, the reflecting surface, the refracting surface, and the eyeball; A display device having a shape having an action. When the angle between the incident central ray on the reflecting surface and the reflected exit ray is θ,
10 ° ≦ θ ≦ 80 °
The display device according to claim 1, wherein the following condition is satisfied. When the power in the azimuth direction in the plane intersecting the original image, the reflection surface, the refraction surface, and the eyeball in the reflection surface is ψ0, and the power in the azimuth direction in a plane perpendicular to the plane is ψ90,
0.3 <$ 0 / $ 90 <1.2
The display device according to claim 1, wherein the display device satisfies the following. 4. The display device according to claim 1, wherein the reflection surface and the refraction surface have different radii of curvature depending on the azimuth direction. 5. The display device according to claim 4, wherein the reflection surface has a surface vertex, and the surface vertex exists independently of each other in the right-eye reflection optical system and the left-eye reflection optical system.

Images