JPH06308423A - Visual display device - Google Patents

Abstract

PURPOSE:To provide a visual display device which can present a large observation viewing angle being >=30 deg., which has the large degree of freedom as for a pupil position and which can present an observed image which is flat and clear extending over the periphery thereof. CONSTITUTION:This device is constituted of a two-dimensional display element on which the observed image is displayed, a conversion optical element converting the flat image on the two-dimensional display element to a curved- surface image 3 and a positive-lens eyepiece optical system 2 which is constituted of two groups and which enlarges and projects the curved-surface image 3 on eyeballs as a virtual image. The optical system 2 is constituted of the first lens group of a positive single lens and the second lens group obtained by joining the negative lens and the positive lens from the eyeball 1 side. Besides, at least one out of the respective surfaces thereof is a non-spherical surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual display device,
In particular, it relates to a portable head- or face-mounted visual display device that can be held on the user's head or face.

[0002]

2. Description of the Related Art In recent years, for the purpose of virtual reality or for the purpose of personally enjoying a large-screen image, a helmet-type or goggle-type visual display device held on the head or face has been developed. For example, there is one in which an image on a small display element such as a liquid crystal display element is enlarged and projected onto an eyeball by an eyepiece optical system such as a lens. An optical system of such a head-mounted visual display device is shown in FIG. In FIG. 10, it is assumed that the two-dimensional display element 5 is 2, the eyepiece lens for magnifying and projecting the two-dimensional display element 5 in the air is 2, and the observer's eyeball position is 10.

The prior art of the eyepiece optical system is a microscope,
There are eyepieces such as binoculars, telescopes and viewfinders (Japanese Patent Laid-Open Nos. 51-120231 and 60-2272).
No. 15, JP-A-61-48810, JP-A-63-31.
851, JP-A-3-87709).

[0004]

For a head- or face-mounted visual display device, it is important to reduce the size of the entire device and reduce its weight in order to improve the wearability. In addition, it is no exaggeration to say that a large angle of view is necessary to increase the sense of realism on the screen, and that the sense of realism is determined by the angle of view presented (Television Society, Vol.45, No. 45). 12, pp.1589-1596 (1991)).

In order to give the observer a sense of presence such as a stereoscopic effect and a feeling of force, it is necessary to secure a presentation angle of view of 30 ° (± 15 °) or more in the horizontal observation direction, and at the same time, 120
It is known that the effect saturates in the vicinity of ° (± 60 °). In other words, 120 ° above 30 °
It is desirable to set the observation angle of view close to.

Further, if the design pupil diameter at the eye point of the eyepiece optical system is small, the degree of freedom of the pupil is small, and even if the state where the apparatus is in close contact is slightly shifted, a dark portion is generated around the observation visual field, impairing the realism. Is not preferable. That is, it is required to reduce the F number of the eyepiece optical system.

However, if the angle of view of the eyepiece optical system is increased and the F-number is decreased, the light ray passes through the peripheral portion of the optical system, so that the occurrence of aberration becomes large, and the aberration can be corrected in a compact structure. It becomes difficult, the resolution of the peripheral image is deteriorated, and the occurrence of image distortion becomes large, which causes distortion of the observed image. Especially for field curvature, with a compact eyepiece with a small number of lenses,
A positive lens is arranged at a position where the ray height is high and a negative lens is arranged at a position where the ray height is low, and it is difficult to correct the Petzval sum due to the positive and negative power distribution.

Although the above-mentioned conventional eyepiece lens has a large angle of view, is it a large F number?
Or, even if the F number is designed to be small, the aberration correction is insufficient, and good aberration correction is achieved while simultaneously securing a large angle of view of 30 ° or more and a small F number. Was difficult. Therefore, it is not possible to simultaneously provide a large image field of view, a large degree of freedom of the pupil position, and a clear image with good flatness up to the periphery, which are important as a visual display device.

The present invention has been made in order to solve such a problem, and an object thereof is to present a large observation angle of view of 30 ° or more, a large degree of freedom of the pupil position, and even the periphery. An object of the present invention is to provide a visual display device capable of presenting a flat and clear observation image.

[0010]

In order to solve the above-mentioned problems, the visual display device of the present invention has a two-dimensional display element for displaying an observation image and a plane image on the two-dimensional display element as a curved surface image. It is characterized by comprising a conversion optical element for conversion and an eyepiece optical system of a positive lens having a two-group configuration for magnifying and projecting the curved surface image on the eyeball as a virtual image.

Further, it is preferable that the curved surface image is a curved surface with a concave surface facing the eyepiece optical system side.

Further, the eyepiece optical system, from the eyeball side,
It is preferable that it is composed of a first lens group of a positive single lens and a second lens group of a cemented lens of a negative lens and a positive lens, and at least one of each surface is an aspherical surface.

Further, in the visual display device of the present invention, the radius of curvature of the object plane converted by the conversion optical element is R,
When the focal length of the eyepiece optical system is F, it is preferable that the condition of 0.5 <| R / F | <2.5 (1) is satisfied.

[0014]

The function and operation of the above configuration will be described below. The points of the present invention are the following two points. The first point is that in order to satisfactorily correct the field curvature aberration, a conversion optical element that converts a plane image on the two-dimensional display element into a curved surface image is used. That is, the configuration is such that an enlarged plane image of a virtual image is projected on the eyeball. In this configuration, the object surface on the two-dimensional display element, which is a flat surface, is canceled by the curvature of field of the eyepiece optical system.
It is important to use a conversion optical element to make a curved object point in advance.
This eliminates the need to correct the field curvature aberration with the eyepiece system, and corrects only the astigmatism without correcting the field curvature aberration, that is, Petzval sum with the two-group lens system as in the present invention. If so, a flat aerial magnified image can be provided.

Further, the curved surface image formed by the conversion optical element is preferably a curved surface with a concave surface facing the eyepiece lens side,
For example, it may be spherical. Generally speaking, the reason for adopting the above configuration is that in a compact eyepiece lens with a small number of lenses, a positive lens is arranged at a position where the ray height is high and a negative lens is arranged at a position where the ray height is low, and the Petzval sum is obtained by positive and negative power distribution. This is because it is not possible to adopt a structure that reduces the size, and field curvature occurs. The direction of curvature corresponds to the direction of curvature of the Petzval image plane, and an eyepiece lens with excessive positive Petzval has a spherical surface with a concave surface facing the eyeball side.
Therefore, by making the curved surface image by the conversion optical element a spherical surface with the concave surface facing the eyepiece lens, the field curvature of the eyepiece lens is canceled out, and as a result, a flat aerial magnified image can be provided.

The above conversion optical element will be described below. In the absence of the conversion optical element, the two-dimensional display element has to be manufactured as a curved surface in order to correct the field curvature, but this is very difficult in manufacturing. Therefore, as described above, the conversion optical element is required to have a function of converting a two-dimensional plane image displayed on the two-dimensional display element into a curved surface image. This conversion optical element can be composed of, for example, a relay lens system in which field curvature is intentionally generated, or can be composed of an image fiber plate or the like having a curved end surface.

The second point of the present invention is that the first lens unit of the positive single lens, the negative lens, and the positive lens are configured as an eyepiece optical system for enlarging and projecting a curved object point as a plane image point in the air. And a second lens group of the cemented lens, and at least one of the surfaces is an aspherical surface.

For the sake of convenience of explanation, the following description will be made on the back ray tracing in which the eyeball pupil is on the object side and the curved surface image by the conversion optical element is the image point. The light ray emitted from the pupil has a higher height of the light ray entering the eyepiece lens system as the angle of view is larger or the F-number is smaller. Therefore, a lens having a strong positive power is arranged first. By making this lens a positive single lens, the ray height is lowered, and the occurrence of aberration is minimized in the lens system that is subsequently incident. The second lens group is a cemented lens of negative and positive lenses with different Abbe numbers in order to correct chromatic aberration. Furthermore, in order to correct the aberration generated on each lens surface due to the large angle of view, an aspherical surface is adopted for at least one of the surfaces. Due to this, with a compact configuration, various aberrations other than field curvature,
In particular, coma and astigmatism can be corrected.

Further, the aspherical surface has a horizontal angle of view of 50.
It is preferable to use at least the eyeball-side surface of the eyepiece lens having a degree of o or more. The reason for this is that when the angle of view exceeds 50 °, the height of the ray incident on the surface closest to the eyeball and the angle of incidence become large, and coma and astigmatism on this surface become extremely large. This is because the correction cannot be completed in terms of surface.

Next, a conditional expression regarding the radius of curvature of the curved object surface by the conversion optical element will be described. When the radius of curvature of the object surface curved by the conversion optical element is R and the focal length of the eyepiece optical system is F, it is important that the condition 0.5 <| R / F | <2.5 (1) is satisfied. Is. If the lower limit of 0.5 of this conditional expression is exceeded, the radius of curvature of the object plane for correcting the field curvature of the eyepiece system in the reverse tracking becomes too small, and the field curvature of the eyepiece system is corrected to this object plane. When assembling is, astigmatism becomes too large, and the resolution of the peripheral image decreases. If the upper limit of 2.5 is exceeded, the astigmatism will increase in the opposite direction, and the resolution of the peripheral image will also decrease. As described above, in order to balance the astigmatism and the field curvature, good results can be obtained if the above conditions are satisfied.

Further, it is more desirable to set the range of the above conditions to 1 <| R / F | <2 (1) '. If it is within the lower limit of this condition, the radius of curvature of the curved object surface can be relaxed to some extent (larger radius of curvature) by the conversion optical element, so that the degree of freedom in designing the conversion optical element is increased and its production is easy. And productivity can be improved. Also, if it is within the upper limit of this condition, the focal length of the eyepiece optical system can be made large to some extent, so that there is a space between the observer eyeball and the eyepiece optical system,
The usability can be improved.

It is more preferable that the focal length of the eyepiece optical system is shorter than the size of the entire apparatus, but the distance (eyepoint) between the eyepiece optical system and the observer's pupil position must be 12 mm or more. Therefore, it is important that the focal length F of the eyepiece optical system satisfies the condition of 12 <F <30 [mm] (2). When the lower limit of 12 to this conditional expression is exceeded, it becomes impossible to secure an eyepoint of 12 mm or more, and the eyelashes of the observer hit the lens, making it difficult to observe. If the upper limit of 30 is exceeded, the eyepiece lens becomes large, sticks out in front of the observer's face, and becomes heavy, which gives the observer a feeling of discomfort or fatigue when the device is worn.

[0023]

EXAMPLES Examples 1 to 5 of the eyepieces and a conversion optical system of the visual display apparatus of the present invention will be described below with reference to the drawings. 1 shows a lens cross-sectional view of Example 1 and FIG. 2 shows an eyepiece lens of Example 4;
Since the lens configuration of (1) is almost the same as that of the first embodiment, its illustration is omitted.

In FIG. 1, reference numeral 1 is the position of the entrance pupil of the eyepiece which is the pupil of the observer's eye, 2 is the eyepiece, and 3 is
Is a curved image surface, and in actual use, the image surface 3
A curved surface image formed by a conversion display element such as a relay optical system 4 (FIG. 8) and an image fiber plate 6 (FIG. 9) which will be illustrated later is arranged on the screen.

Now, the eyepiece lens 2 is used in Examples 1-3, 5 and 5.
1 includes a biconvex lens from the pupil 1 side and a cemented lens of a negative meniscus lens having a convex surface facing the pupil 1 side and a biconvex lens from the pupil 1 side, and in Example 4, FIG. As shown in FIG. 3, it is composed of, from the pupil 1 side, a positive meniscus lens having a convex surface facing the pupil 1 side, a negative meniscus lens having a convex surface facing the pupil 1 side, and a cemented doublet lens.

Regarding the aspherical surface of the eyepiece lens 2, in the first embodiment, both surfaces of the single lens are used, and in the second embodiment, there are two surfaces, that is, the surface of the single lens on the pupil 1 side and the surface of the cemented lens on the image surface 3 side. Surface, in Embodiment 3, on the surface 1 on the pupil 1 side of the single lens, and in Embodiment 4, the cemented lens image surface 3
It is used as the first surface on the side, and in Example 4 as the first surface on the pupil 1 side of the cemented lens.

In Examples 1 and 2, the observation horizontal direction angle of view was 50 °.
(± 25 °), diagonal angle of view 63 °, Examples 3 to 5 are observation horizontal direction angle of view 40 ° (± 20 °), diagonal angle of view 50 °, In all the examples, the pupil diameter is φ
It is 8 mm.

Hereinafter, the lens data of the reverse tracking of the above Examples 1 to 5 will be shown. The symbols are the above, r ₀ is the pupil 1, and
d ₀ is the eye point, r ₁ to r ₅ are the radii of curvature of the lens surfaces of the eyepiece 2, d ₁ to d ₄ are the intervals between the lens surfaces of the eyepiece 2, and n _{d1 to} n _d3 are the eyepieces. The d-line refractive index of each lens of the lens 2, v _{d1 to} v _d3 represent the Abbe number of each lens of the eyepiece lens 2, and d ₅ is between the final surface (fifth surface) of the eyepiece lens 2 and the image plane 3. , R ₆ represents the image plane 3. In addition, the aspherical shape is such that the distance from any point on the aspherical surface to the tangent plane of the aspherical surface vertex is Z, the distance from this arbitrary point to the optical axis is h, the reference radius of curvature is r, and the conic constant is When K and the aspherical surface coefficients are A, B, ... ^{Z = (h 2 / r)} / {1+ [1- (1 + K) (h / r) 2 ] ^{1/2} + Ah 4 + Bh 6} + ····.

Example 1 r ₀ = ∞ d ₀ = 15.000000 r ₁ = 19.16777 (aspherical surface) d ₁ = 17.282117 n _d1 = 1.5254 ν _d1 = 56.25 r ₂ = -17.96050 (aspherical surface) d ₂ = 0.603569 r ₃ = 74.17377 d ₃ = 2.000000 n _d2 = 1.8466 ν _d2 = 23.9 r ₄ = 13.36589 d ₄ = 14.889812 n _d3 = 1.5163 ν _d3 = 64.1 r ₅ = -28.46670 d ₅ = 4.673707 r ₆ = -27.57725 Aspheric surface 1st surface K = -2.895470 A = 0.183708 × 10 ^-4 B = -0.911517 × 10 ^-8 Second surface K = -1.518426 A = 0.294718 × 10 ^-4 B = -0.265912 × 10 ^-7
.

Example 2 r ₀ = ∞ d ₀ = 15.000000 r ₁ = 21.09188 (aspherical surface) d ₁ = 12.729671 n _d1 = 1.5254 ν _d1 = 56.25 r ₂ = -98.25692 d ₂ = 0.795885 r ₃ = 31.10831 d ₃ = 2.000000 n _d2 = 1.8466 ν _d2 = 23.9 r ₄ = 14.16702 d ₄ = 16.000000 n _d3 = 1.5254 ν _d3 = 56.25 r ₅ = -22.08546 (aspherical surface) d ₅ = 8.474444 r ₆ = -32.00736 aspherical surface 1st surface K = -0.980510 A = 0.138364 × 10 ^-5 B = 0.188699 × 10 ^-8 Fifth surface K = -14.627343 A = -0.180394 × 10 ^-4 B = 0.986111 × 10 ^-7
.

Example 3 r ₀ = ∞ d ₀ = 15.000000 r ₁ = 19.42583 (aspherical surface) d ₁ = 13.000000 n _d1 = 1.5254 ν _d1 = 56.25 r ₂ = -39.06931 d ₂ = 2.853699 r ₃ = 30.82547 d ₃ = 2.000000 n _d2 = 1.8466 ν _d2 = 23.9 r ₄ = 11.35921 d ₄ = 13.000000 n _d3 = 1.5163 ν _d3 = 64.1 r ₅ = -44.22965 d ₅ = 6.686127 r ₆ = -26.09666 Aspheric surface 1st surface K = -1.202641 A = -0.439027 x 10 ^-5 B = 0.778743 x 10 ^-8
.

Example 4 r ₀ = ∞ d ₀ = 15.000000 r ₁ = 20.33823 d ₁ = 6.050349 n _d1 = 1.6204 ν _d1 = 60.27 r ₂ = 45.00722 d ₂ = 0.200000 r ₃ = 21.95813 d ₃ = 2.000000 nd ₂ = 1.8466 ν _d2 = 23.9 r ₄ = 12.20347 d ₄ = 13.000000 n _d3 = 1.5254 ν _d3 = 56.25 r ₅ = -28.27427 (aspherical surface) d ₅ = 13.758914 r ₆ = -37.35309 Aspherical surface 5th surface K = -16.260810 A = -0.281706 × 10 ^-5 B = 0.100959 × 10 ^-6
.

Example 5 r ₀ = ∞ d ₀ = 15.000000 r ₁ = 20.68370 d ₁ = 12.837937 n _d1 = 1.6204 ν _d1 = 60.27 r ₂ = -119.37864 d ₂ = 2.123186 r ₃ = 61.75341 (aspherical surface) d ₃ = 2.000000 n _d2 = 1.8466 ν _d2 = 23.9 r ₄ = 17.08252 d ₄ = 13.000000 n _d3 = 1.5254 ν _d3 = 56.25 r ₅ = -32.09057 d ₅ = 10.038296 r ₆ = -33.95088 Aspheric surface third surface K = -82.607990 A = 0.662382 × 10 ^-5 B = -0.201298 × 10 ^-6
.

Next, FIG. 3 to FIG. 3 show aberration diagrams showing spherical aberration, astigmatism, distortion, and lateral aberration of Examples 1 to 5, respectively.
It shows in FIG. In addition, the conditional expression (1) of Examples 1 to 5,
The values corresponding to (2) are as shown in Table 1 below.

[0035]

Such a curved image plane 3 has a relay optical system 4 in which an image field curvature is intentionally generated as shown in FIG. 8 and an image fiber plate 6 as shown in FIG.
It can be obtained by converting the plane image plane of the two-dimensional display element 5 by a conversion optical element including the above. The display surface of the two-dimensional display element 5 may be curved to form the curved image plane 3.

[0037]

As described above, according to the visual display device of the present invention, a large viewing angle of view of 30 ° or more can be presented, the degree of freedom of the pupil position is large, and the periphery is flat and clear. A visual display device capable of presenting an observation image can be provided.

[Brief description of drawings]

FIG. 1 is a lens cross-sectional view of an eyepiece lens of Example 1 of a visual display device according to the present invention.

FIG. 2 is a lens cross-sectional view of an eyepiece lens of Example 4.

FIG. 3 shows the spherical aberration and astigmatism of the eyepiece of Example 1.
FIG. 4 is an aberration diagram showing distortion and lateral aberration.

FIG. 4 is an aberration diagram similar to FIG. 3 of the eyepiece lens of Example 2.

FIG. 5 is an aberration diagram for the eyepiece lens of Example 3, similar to FIG.

FIG. 6 is an aberration diagram similar to FIG. 3 of the eyepiece lens of Example 4.

FIG. 7 is an aberration diagram for the eyepiece lens of Example 5, similar to FIG.

FIG. 8 is a diagram showing an optical system of a visual display device of the present invention using a relay optical system as a conversion optical element.

FIG. 9 is a diagram showing an optical system of a visual display device of the present invention using an image fiber plate as a conversion optical element.

FIG. 10 is a diagram showing an optical system of a conventional head-mounted visual display device.

[Explanation of symbols]

 1 ... Entrance pupil position of eyepiece 2 ... Eyepiece 3 ... Curved image plane 4 ... Relay optical system 5 ... Two-dimensional display element 6 ... Image fiber plate

Claims (1)

[Claims] 1. A two-dimensional display element for displaying an observation image, a conversion optical element for converting a plane image on the two-dimensional display element into a curved surface image, and the curved surface image enlarged and projected as a virtual image on an eyeball.
A visual display device comprising a positive lens eyepiece optical system having a group configuration.