JPH05303056A - Vision display device - Google Patents

Abstract

PURPOSE:To obtain the portable type vision display device which can observe an image in which an image distortion scarcely exists. CONSTITUTION:In the vision display device provided with a two-dimensional display element 7 for displaying an observation image, and an eyepiece optical system 6 for enlarging and projecting the two-dimensional display element 7 or its real image into the air, and also, bending an optical axis, the eyepiece optical system 6 is constituted of an aspherical concave mirror, and the concave mirror 6 is constituted so that a curvature of the surface in the direction (X direction) being orthogonal to the surface (Y-Z surface) for bending the optical axis becomes gradually higher as it goes toward the direction (-Y direction) for bending the optical axis, in the case it is looked at from an eyeball 1 of an observer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable visual display device, and more particularly to a head- or face-mounted visual display device that can be held on the head or face of an observer.

[0002]

2. Description of the Related Art Conventionally, as a face-mounted visual display device,
A device having a plan view shown in FIG. 10 is known (US Pat. No. 4,026,641). This is because the image of the image display device 46 such as a CRT is displayed on the object plane 12 by the image transfer device 25.
To the toric reflecting surface 10
It is designed to be projected in the air by.

[0003]

By the way, in such a face-mounted type visual display device, it is important to reduce the size of the entire device in order to prevent the wearability. In order to reduce the size of the entire device, it is necessary to arrange the two-dimensional image display element above the observer's head or beside the head. For that purpose, it is important to use an eccentric reflecting surface that reflects the optical axis of an observer who observes the front and bends (angle-deflects) the reflected optical axis to the side of the observer's eyeball position. However, the optical axis referred to here is a so-called on-axis ray that is a ray that passes through the center of the iris of the eyeball of the observer or the center of rotation of the eyeball and that exits the display center of the two-dimensional image display element.

If the reflecting surface is not concave, it is difficult to secure a wide angle of view unless the size of the image display element is large, and the entire device becomes large. Further, since it is necessary to secure a wide angle of view in order to increase the realism at the time of observing an image, it is necessary to dispose a large reflecting surface.

From the above two points, in the optical arrangement of the face-mounted visual display device, it is necessary to arrange a relatively large concave mirror in front of the eyes of the observer.

However, if the above-mentioned structure is adopted and the concave mirror is made large in order to secure a wide observation angle of view, trapezoidal image distortion occurs. The cause of the trapezoidal image distortion will be described below with reference to FIG.

FIG. 1 is a bird's-eye view of the state of a light beam from the observer's iris position in the figure to the two-dimensional image display element or the projection position of the two-dimensional image display element. FIG. 1 shows the optical arrangement of the visual display device of the present invention for the right eye of the observer. In this figure, the Y axis is the direction in which the concave mirror 6 bends the optical axis and is horizontal for the observer. The positive direction of the Y-axis corresponds to the center direction of the observer's head, that is, the left direction. The X-axis corresponds to the vertical direction for the observer, and the positive direction of the X-axis corresponds to the lower part of the observer's head.

In FIG. 1, reference numeral 1 is the observer's iris position or eyeball rotation position. Reference numeral 2 denotes a light beam having an observation angle of view of 15 ° to the left in the horizontal direction for the observer, and reference numeral 3 similarly denotes downward 1 ° of 15 ° to the left.
The luminous flux is 0 °. 4 is the right horizontal direction 1 for the observer
A luminous flux having an observation angle of view of 5 °, and 5 is a luminous flux of 10 ° below the right 15 °. Reference numeral 6 denotes a concave mirror which is the eyepiece optical system, and 7 denotes a focal plane of the concave mirror 6 on which a two-dimensional image display element or a projected image of the two-dimensional image display element is arranged.

Here, in FIG. 1, for the sake of explanation, in order to show how an ideal light beam observed by an observer in a rectangular shape is imaged by the concave mirror 6, the concave mirror focus is changed from the eyeball position 1 of the observer. It traces back rays up to 7.

In the concave mirror focal plane 7 of FIG. 1, conventional spherical or aspherical surfaces (toric surface, anamorphic hook surface, parabolic surface,
(Ellipsoidal surface), etc.
Trapezoidal image distortion occurs in which the height of the image in the axial direction differs. This is because from the exit pupil of the eyepiece optical system 6 arranged near the center of eyeball rotation of the observer 1 in FIG.
This is because the optical distance up to is significantly different depending on the angle of view in the Y-axis direction, which is the observation direction of the observer. That is, since the optical axis of the concave reflecting mirror 6 and its pupil 1 are decentered, the light fluxes 4 and 5 observed in the negative direction of the Y-axis direction from 1 in FIG. 1 are also in the positive direction of the Y-axis direction. As compared with the observed light fluxes 2 and 3, the optical distance to the concave reflection mirror 6 until the light flux hits and is reflected is long, so the light flux is sufficiently spread before being reflected. That is, when the light flux strikes the concave mirror 6, the distance between the light fluxes 4 and 5 is wider than the distance between the light fluxes 2 and 3.

For the above reason, in the decentered optical system in which the optical axis is bent by the concave mirror 6 which is the eyepiece optical system in which the optical axis is inclined, the direction orthogonal to the direction in which the optical axis is bent (in FIG. 1, , X-axis direction) varies depending on the direction in which the optical axis is bent (positive and negative on the Y-axis). Therefore, it is observed as a trapezoidal image distortion by the observer.

In the conventional example in which a toric surface is used as a reflecting mirror, image distortion as shown in FIG. 11 occurs. Further, the image distortion when an elliptical surface is used as the reflecting surface is as shown in FIG. 12, and even if a spherical surface is used, the trapezoidal image distortion similarly occurs. Therefore, in the conventional technique, only a distorted image can be observed, resulting in an unnatural observation image. In addition,
In FIGS. 11 and 12, the size of a rectangular ideal image of 15 ° left and right and 10 ° downward is indicated by a broken line, and the image due to the generated image distortion is indicated by a solid line. The method of obtaining the coordinates is the same as in FIG.

When observing the same image with both eyes at the same time, when trying to observe images in the same direction with the right eye and the left eye,
The size of the image is different, and it is difficult to fuse the images, or the images cannot be fused at all and are observed as double images.

Further, when an image having parallax on the left and right is observed and stereoscopic vision is to be performed, the stereoscopic effect cannot be obtained unless the left and right images are fused.

The present invention has been made to solve such a problem, and an object thereof is to provide a portable visual display device capable of observing an image with little image distortion.

[0016]

A visual display device of the present invention which achieves the above object comprises a two-dimensional display element for displaying an observation image, an enlarged projection of the two-dimensional display element or its real image in the air, and an optical axis. In the visual display device having an eyepiece optical system for bending, the eyepiece optical system is composed of an aspherical concave mirror, and the curvature of the surface of the concave mirror in a direction orthogonal to the surface for bending the optical axis is an observer. When viewed from the eyeball, it is configured such that it gradually increases as it goes in the direction of bending the optical axis.

[0017]

The function and operation of adopting the above configuration will be described below. In the present invention, the partial curvature in the direction of the surface orthogonal to the surface that bends the optical axis of the concave reflecting mirror that is the eyepiece optical system,
By using an aspherical concave mirror that is gradually tight along the direction in which the optical axis is bent, the trapezoidal image distortion is successfully corrected.

The operation of the present invention will be described with reference to FIG. In the light fluxes 2 and 3 of the Y-axis positive direction (on the side opposite to the light flux bending direction) in which the image height in the X-axis direction becomes small, the light fluxes 2 and 3 hit the reflecting mirror 6 and reach the focal plane 7 of the reflecting mirror. With respect to the inter-optical axis interval, it is possible to correct the decrease in the image height in the X-axis direction by making the curvature in the X-axis direction of the portion where the light fluxes 2 and 3 are reflected relatively small.

On the other hand, in the Y-axis negative light beams 4 and 5 in which the image height in the X-axis direction becomes large, the light beams 4 and 5 reach the focal plane 7 of the reflection mirror 6 after hitting the reflection mirror 6. The distance between the optical axes of the light beams 4 and 5 can be corrected by making the curvature in the X-axis direction relatively tight so that the image height in the X-axis direction becomes large.

Therefore, the trapezoidal image distortion due to the eccentric arrangement of the concave reflecting mirror 6 can be corrected.

[0021]

EXAMPLES Examples 1 to 3 of the visual display device of the present invention will be described below.
Will be described. Example 1 This example will be described with reference to FIG. FIG. 2 is a cross section in the Y-axis direction of FIG. 1, and how the concave mirror 6 is decentered with respect to the observer's iris position or the eyeball rotation center position 1 depends on the coordinate system of FIG. In the figure, 7 is a two-dimensional image display device or a projected image of the two-dimensional image display device, 6 is a concave anamorphic aspherical reflecting mirror, and 1 is an observer iris position or an eyeball rotation center position (hereinafter referred to as an exit pupil). It is). The axis of the concave reflecting mirror 6 is 6a, the distance from the center of the exit pupil 1 to the axis 6a of the reflecting mirror 6 (the amount of eccentricity) is Y ₁ , and the distance from the center of the two-dimensional image display element 7 to the axis 6a (the amount of eccentricity) is and Y _2.
In the case of the coordinate system of FIG. 2, the eccentricity amounts Y ₁ and Y ₂ are both given negatively. Further, the inclination angle of the surface perpendicular to the axis 6a with respect to the surface in contact with the center of the two-dimensional image display element 7 is α. In the figure, α is positive.

The constituent parameters of this optical system will be shown below. The surface numbers are from the position of the exit pupil 1 to the two-dimensional image display element 7.
It is shown as a backtracking face number towards. For the aspherical shape, the coordinate system is set as shown, and the paraxial radius of curvature of the concave reflecting mirror 6 and the two-dimensional image display element 7 is set in the vertical direction (X-
When the Z plane) is R _x and the left-right direction (YZ plane) is R _y ,
It is expressed by the following formula. ^{Z = [(X 2 / R} x) + (Y 2 / R y)] / [1+ {1- (1 + K x) (X 2 / R x 2) - (1 + K y) (Y 2 / R _y ² )} ^1/2 ] + AR [(1-AP) X ² + (1 + AP) Y ² ] ² + BR [(1-BP) X ² + (1 + BP) Y ² ] ³ + CR [ (1-CP) X ² + (1 + CP) Y ² ] ⁴ where K _x is the conical coefficient in the X direction, K _y is the conical coefficient in the Y direction, and AR, BR, and CR are rotationally symmetric fourth-order , 6
Next-order and eighth-order aspherical coefficients, AP, BP, and CP are asymmetrical fourth-order, sixth-order, and eighth-order aspherical coefficients, respectively.

Surface number Radius of curvature Surface spacing Eccentricity ₁ Exit pupil (1) 50.0 Y ₁ -28.285 2 R _y 59.071 (6) 22.39 Y ₂ -6.0247 R _x 43.981 (aspherical) 3 R _y 36.164 (image plane 7) R _x 10.699 (aspherical surface) aspherical surface coefficient second surface (concave mirror 6) K _y = 0 K _x = 0 AR = -0.127331 × 10 ^-5 AP = -0.585287 BR = 0 BP = 0 CR = 0 CP = 0 Three planes (image plane 7) K _y = 0 K _x = 0 AR = 0 AP = 0 BR = 0 BP = 0 CR = 0 CP = 0 α = 15.8529 ° The image distortion of this example is shown in FIG. In FIG. 4, the dotted line shows the ideal image position and the solid line shows the actual image forming position of this optical system. A lateral aberration diagram for this example is shown in FIG. In the figure, (a) is the aberration in the left-right direction and the vertical direction when an image at the left side (+ Y direction) 15.0 ° is seen from a straight line passing through the center of the pupil 1 and parallel to the axis 6a, and (b) is this straight line. The horizontal and vertical aberrations when viewing an image in a certain direction, and (c) is the horizontal and vertical aberrations when viewing an image at 15.0 ° to the right (-Y direction) from this straight line. is there.

Example 2 This example is basically the same as Example 1. The difference is that the concave mirror 6 is a rotationally symmetric aspherical reflecting mirror. Hereinafter, the parameters of the optical system will be shown using the same symbols as in Example 1. The aspherical shape is expressed by the following equation when the coordinate system is as shown in FIG. 2 and R is the paraxial radius of curvature. Z = (h ² / R) / [1+ {1- (1 + K) (h ² / R ² )} ^1/2 ] +
Ah ⁴ + Bh ⁶ + Ch ⁸ (h ² = X ² + Y ² ), where K is the conical coefficient, A, B, and C are fourth-order and 6 respectively.
Next is the aspherical coefficient of the 8th order.

Surface number Radius of curvature Surface spacing Eccentricity ₁ Exit pupil (1) 50.0 Y ₁ -28.285 2 52.0154 (6) 22.398 Y ₂ -6.025 (aspherical surface) 3 29.8172 (image surface 7) aspherical coefficient second surface ( Concave mirror 6) K = 0 A = -0.124395 × 10 ^-5 B = 0 C = 0 α = 12.318 ° The image distortion of this example is shown in FIG. 8 is a lateral aberration diagram for this example. The notation method is the same as that in FIGS. 4 and 7, respectively.

Example 3 In this example, as shown in FIG. 3, the image of the two-dimensional image display element 7 is converted into an aerial image on the object plane (focal plane) 9 of the concave mirror 6 by using the relay optical system 8. It is an image.
The concave mirror 6 is an anamorphic aspherical reflecting mirror. The optical axis of the relay optical system 8 is 8a, the eccentric amount of the axis 6a of the reflecting mirror 6 with respect to the center of the exit pupil 1 is Y ₁ , the eccentric amount of the axis 6a with respect to the center of the first surface of the relay optical system Y _{2 is} two-dimensional. The eccentric amount of the optical axis 8a of the relay optical system 8 in the Y-axis direction from the center of the display element 7 is Y ₃ , the tilt angle of the axis 6a of the concave mirror 6 with respect to the optical axis 8a of the relay optical system 8 is α ₁ , and the two-dimensional display element 7 The inclination angle of the surface perpendicular to the optical axis 8a of the relay optical system 8 with respect to the display surface is defined as α ₂ . Therefore, in the case of FIG. 3, Y ₁ is negative, Y ₂ is positive, Y ₃ is negative, α ₁ is positive, and α ₂ is positive.

The constituent parameters of this optical system are shown below. The surface numbers are from the position of the exit pupil 1 to the two-dimensional image display element 7.
It is shown as a backtracking face number towards. As for the surface distance, the distance between the exit pupil 1 and the concave mirror 6 in the Z-axis direction between the center of the exit pupil 1 and the center of the concave mirror 6, the relay optical system 8
The distance from the first surface to the image surface (two-dimensional image display element 7) is indicated by the distance along the optical axis 8a. For the relay optical system 8, the lens surfaces from the first surface to the seventh surface are r ₁ to
In r _7, showing a surface interval d ₁ to d _7. Surface number Curvature radius Spacing Eccentricity Tilt angle Refractive index 1 (1) Exit pupil 50.0 Y ₁ -28.285 2 (6) R _y 65.909 Y ₂ 28.2546 α ₁ 53.1889 ° R _x 39.151 (aspherical) 3 (r ₁ ) -17.439 4.0 (d ₁ ) 1.72916 4 (r ₂ ) -16.374 1.0 (d ₂ ) 5 (r ₃ ) 40.383 4.0 (d ₃ ) 1.72916 6 (r ₄ ) -43.930 1.0 (d ₄ ) 7 (r ₅ ) 10.688 6.0 ( d ₅ ) 1.51633 8 (r ₆ ) -16.881 2.0 (d ₆ ) 1.80518 9 (r ₇ ) -188.062 10.0 (d ₇ ) 10 (7) Image plane Y ₃ -0.19518 α ₂ 12.94946 ° Aspherical surface 2nd surface ( Concave mirror 6) K _y = 0 K _x = 0 AR = -0.109807 × 10 ^-5 AP = -0.640989 BR = 0.281845 × 10 ^-13 BP = 0.203281 × 10 ² CR = 0 CP = 0 The image distortion of this example is illustrated. 6 shows. A lateral aberration diagram for this example is shown in FIG. The notation method is the same as in FIGS. 4 and 7, respectively.

In this embodiment, the two-dimensional display element 7
Can be enlarged and projected by the relay optical system 8, so that a small-sized display element 7 can be used, and there is an advantage that the entire apparatus can be downsized.

In each of the above-mentioned embodiments, the concave reflecting mirror 6 may be a semi-transmissive mirror as well as a total reflecting mirror. It is a well known fact that a semi-transmissive mirror can be combined with an external image.

Although the visual display device of the present invention has been described with reference to some embodiments, the present invention is not limited to these embodiments and various modifications can be made.

[0031]

As is clear from the above description, according to the visual display device of the present invention, there is little distortion.
It is possible to provide a head- or face-mounted visual display device that is clear and has a wide angle of view.

[Brief description of drawings]

FIG. 1 is a bird's-eye view showing a state of light flux in a visual display device of the present invention.

FIG. 2 is a diagram showing an optical arrangement of the visual display device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an optical arrangement of Example 3;

FIG. 4 is a diagram showing image distortion of Example 1.

FIG. 5 is a diagram showing image distortion in Example 2;

FIG. 6 is a diagram showing image distortion in Example 3;

7 is a lateral aberration diagram for Example 1. FIG.

8 is a lateral aberration diagram for Example 2. FIG.

9 is a lateral aberration diagram for Example 3. FIG.

FIG. 10 is a plan view of a conventional face-mounted visual display device.

FIG. 11 is a diagram showing image distortion due to a conventional toric surface.

FIG. 12 is a diagram showing conventional image distortion due to an ellipsoid.

[Explanation of symbols]

1 ... Observer iris position or eyeball rotation position 2 ... Luminous flux with an observation angle of view of 15 ° on the left side 3 ... 15 ° left side, luminous flux with an angle of view of 10 ° below 4 ... Light flux 5 ... Light flux with observation angle of view of 15 ° on right side and 10 ° below 6 ... Eyepiece optical system (concave mirror) 7 ... Projected image of 2D image display element or 2D image display element 8 ... Relay optical system 9 ... Object of concave mirror Surface (focal plane) 6a ... Axis of concave mirror 8a ... Optical axis of relay optical system

Claims (1)

[Claims] 1. A visual display device comprising a two-dimensional display element for displaying an observation image, and an eyepiece optical system for enlarging and projecting the two-dimensional display element or a real image thereof in the air and bending the optical axis, wherein the eyepiece The optical system consists of an aspherical concave mirror,
It is characterized in that the concave mirror is configured such that the curvature of the surface in the direction orthogonal to the surface for bending the optical axis gradually increases in the direction for bending the optical axis when viewed from the eyeball of the observer. Visual display device.