JP2001013446A - Observation optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To view the external environment or the like similarly to a case that it is viewed with naked eyes when it is viewed in a see-through state through an eyepiece optical system such as a prism optical system forming a display picture. SOLUTION: This observation optical system is provided with a picture display element 3, the eyepiece optical system 10 guiding the display image of the element 3 to the eyeballs of an observer and a see-through optical element 20 arranged at the more external environment side than the optical system 10 so as to guide an external-environment picture being different from the display picture to the eyeballs of the observer. Then, the optical system 10 is provided with a curved reflection surface 12 reflecting luminous flux from the display picture to the observer side and the reflection surface 12 is provided with such as action that the luminous flux from the external-environment picture transmitted through the element 20 is transmitted. Besides, the element 20 is arranged at interval from the reflection surface 12. Then, when the luminous flux from the external-environment picture is transmitted through the element 20 and the optical system 10, synthetic optical power P becomes almost zero and angular magnification β becomes almost 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an observation optical system, and more particularly to, for example, a see-through observation optical system in an optical system of a head-mounted image display apparatus, which is viewed through an external environment or the like.

[0002]

2. Description of the Related Art Conventionally, with respect to an optical system such as a head-mounted image display device, U.S. Pat. No. 4,969,724 and European Patent No. 5,831,116-A2 both use eyepiece optics. The surface of a prism optical system constituting a system is constituted by a plane, and in Japanese Patent Application Laid-Open No. 7-333551, the surface of a prism optical system constituting an eyepiece optical system is constituted by a rotationally asymmetric anamorphic surface. ing.

[0003]

In order to form a sheath optical system for seeing through the outside world or the like with a thick prism optical system constituting such a conventional eyepiece optical system, the surface on the eye side and the surface on the outside world must be arranged. In general, the power of the see-through optical path is set to 0 with the same shape.

However, when the surface of the prism optical system on the eye side is not flat, even if the power of the see-through optical path is 0, the angular magnification is not 1 and one prism optical system is set to the other eye with the naked eye. In the case of a head-mounted image display device of a one-eye mounting type, which is observed with a single eye, there is a problem that when viewed with both eyes, two images cannot be fused with the left and right eyes.

The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a see-through through an eyepiece optical system such as a prism optical system for forming a display image from an image display device. An object of the present invention is to provide an observation optical system in which the outside world and the like can be seen when the outside world and the like are seen with the naked eye.

[0006]

According to an aspect of the present invention, there is provided an observation optical system comprising: an image forming member for forming a first image to be observed by an observer; and an image formed by the image forming member. An eyepiece optical system configured to guide the second image different from the first image to an observer's eyeball; and a see-through optical element disposed closer to the second image than the eyepiece optical system. In the observation optical system provided with, the eyepiece optical system has at least a curved reflection surface so as to reflect the light flux from the first image and guide it toward the observer's eyeball, and the reflection surface is It is configured to have a function of transmitting a light flux from the second image transmitted through the see-through optical element, and the see-through optical element is disposed closer to the second image than the reflective surface and spaced apart from the reflective surface. And the light flux from the second image is transmitted through the sheath -When transmitted through the optical element and the eyepiece optical system, the combined optical power P of the see-through optical element and the eyepiece optical system is substantially zero, and the angular magnification β is substantially one. It is characterized by having.

Hereinafter, the reason and operation of the above-mentioned configuration in the present invention will be described. FIG. 1 is an optical path diagram of an observation optical system of Example 1 described later. Referring to this drawing, the eyepiece optical system of this observation optical system is configured to include a prism optical system 10. The prism optical system 10 is counted from the exit pupil 1 side by backward ray tracing, and Display light from the image display element arranged on the image plane 3 includes a first surface 11 also serving as a total reflection surface, a second surface 12 as a semi-transmissive reflection surface, and a third surface 13 as a transmission surface. The light enters the prism optical system 10 from the surface 13, and the incident light is reflected by the first surface 11, further reflected by the second surface 12, exits the prism from the first surface 11, and is located at the position of the exit pupil 1. Is incident on the observer's eyeball at which is located, and the display image on the image plane 3 can be magnified and observed.

[0008] In front of the second surface 12 of the prism optical system 10, there is an interval (including one having an axial interval of 0).
See-through optical element 20 made of another transmission prism member
Are disposed, counted from the exit pupil 1 side by backward ray tracing, and are constituted by a first surface 21 and a second surface 22 which are transmission surfaces. Light from the outside is transmitted from the second surface 22 of the see-through optical element 20 to the second surface 22. One surface 21, second surface 12 of prism optical system 10, first surface 1
1 and is incident on the observer's eyeball where the pupil is located at the position of the exit pupil 1 to form an external image. The external image and the display image of the image display element on the image plane 3 are observed selectively or superimposed. In FIG. 1, reference numeral 2 indicates an axial principal ray.

As described above, in the present invention, an image forming member (an image display element on the image plane 3) for forming a first image to be observed by an observer, and the image formed by the image forming member is placed on an observer's eyeball. An eyepiece optical system configured to guide the light (in this case, a prism optical system 10 and a diffractive optical element 4);
An observation optical system including a see-through optical element 20 disposed closer to the second image than the eyepiece optical system so as to guide a second image (in this case, an external image) different from the first image to the observer's eyeball. , The eyepiece optical system reflects at least a curved reflecting surface 1 so as to reflect the light flux from the first image and guide it toward the observer's eyeball.
2, the reflection surface 12 is configured to have a function of transmitting a light beam from the second image transmitted through the see-through optical element 20, and the see-through optical element 20 is closer to the second image than the reflection surface 12, It is arranged at a distance from the reflection surface 12.

In the present invention, the light flux from the outside world is
When the light passes through the see-through optical element 20 and the prism optical system 10, the combined optical power P of the see-through optical element 20 and the prism optical system 10 becomes approximately 0, and the angular magnification β becomes approximately 1. It is characterized by having. Here, both the optical power and the angular magnification are the optical power and the angular magnification at the position where the axial principal ray 2 passes.

As described above, by setting the optical power P of the see-through optical system to approximately 0 and the angular magnification β to approximately 1, the image viewed through the see-through optical system becomes the same as the image viewed with the naked eye, An image viewed with the naked eye and an image viewed through the see-through optical system are easily fused, and for example, an external image can be easily observed with both eyes in a one-eye mounted head-mounted image display device.

Here, the optical power P being substantially 0 means that the optical power P is in the range of -0.002 <P <0.002 (1 / mm) (1). If the upper and lower limits of this condition are exceeded, the image formed through the see-through optical system and the image formed by the naked eye have too different image formation positions, making observation with both eyes difficult.

The angular magnification β of about 1 means 0.95 <β <1.05 (2). If the upper and lower limits of this condition are exceeded, the image viewed through the see-through optical system and the image viewed with the naked eye will not be formed to the same size, and it will be difficult for the left and right images to be fused with both eyes.

Separating the distance between the eyepiece optical system and the see-through optical element means that the optical member and the optical member are joined by an adhesive having substantially the same refractive index, and the generation of optical power at the joint surface can be ignored. The optical power (for example, air lens) generated between the eyepiece optical system and the see-through optical element also means an effect that contributes to the optical performance of the see-through optical system, and is separated by air. Not only that, but also those bonded with an adhesive having a difference in refractive index, and those in which a liquid, gas, or fluid is sealed. In addition, a liquid crystal shutter may be arranged between them.

Here, it is preferable from the viewpoint of aberration correction that the reflecting surface of the eyepiece optical system has a rotationally asymmetric curved surface shape for correcting eccentric aberration.

The reason will be described in detail below: First, a coordinate system to be used and a rotationally asymmetric surface will be described. The optical axis defined by a straight line until the on-axis principal ray intersects the first surface of the eyepiece optical system in the reverse ray tracing is defined as the Z axis, and each axis is orthogonal to the Z axis and constitutes the eyepiece optical system. An axis in an eccentric plane of the surface is defined as a Y axis, and an axis orthogonal to the optical axis and orthogonal to the Y axis is defined as an X axis. The ray tracing direction will be described in the case of reverse ray tracing from the exit pupil to the image display surface.

In general, in a spherical lens system composed only of spherical lenses, spherical aberration caused by a spherical surface, aberration such as coma, and field curvature are mutually corrected on several surfaces, so that the aberration is reduced as a whole. Configuration.

On the other hand, in order to favorably correct aberrations with a small number of surfaces, a rotationally symmetric aspherical surface or the like is used. This is to reduce various aberrations generated on the spherical surface.

However, in a decentered optical system, it is impossible to correct rotationally asymmetric aberrations caused by decentering by a rotationally symmetric optical system. The rotationally asymmetric aberrations caused by this eccentricity include distortion, field curvature, astigmatism and coma which also occur on the axis.

First, the rotationally asymmetric field curvature will be described. For example, light rays incident on a concave mirror decentered from an object point at infinity are reflected and imaged on the concave mirror, but after the light rays hit the concave mirror, the rear focal length to the image plane is
When the image field side is air, the radius of curvature becomes half of the radius of curvature of the portion hit by the light beam. Then, as shown in FIG. 21, an image plane inclined with respect to the axial principal ray is formed. As described above, it is impossible to correct rotationally asymmetric curvature of field with a rotationally symmetric optical system.

In order to correct the tilted curvature of field by the concave mirror M itself, which is the source, the concave mirror M is constituted by a rotationally asymmetric surface. In this example, the curvature is strong in the positive Y-axis direction ( If the refractive power is increased) and the curvature is decreased (the refractive power is decreased) in the negative direction of the Y axis, the correction can be made. In addition, by arranging a rotationally asymmetric surface having the same effect as the above configuration in the optical system separately from the concave mirror M, a flat image surface can be obtained with a small number of components.

The rotationally asymmetric surface preferably has a rotationally asymmetric surface shape having no rotationally symmetric axis both inside and outside the surface, which is preferable for increasing the degree of freedom and correcting aberrations.

Next, rotationally asymmetric astigmatism will be described. As described above, the eccentrically arranged concave mirror M
In this case, astigmatism as shown in FIG. 22 also occurs for axial rays. Astigmatism can be corrected by appropriately changing the curvature in the X-axis direction and the curvature in the Y-axis direction of the rotationally asymmetric surface, as described above.

Further, rotationally asymmetric coma will be described. Similarly to the above description, in the concave mirror M arranged eccentrically, coma as shown in FIG. To correct the coma aberration, the inclination of the surface can be changed as the distance from the origin of the X axis of the rotationally asymmetric surface increases, and the inclination of the surface can be appropriately changed depending on the sign of the Y axis.

Further, in the eyepiece optical system of the present invention, it is also possible to adopt a configuration in which at least one surface having the above-mentioned reflecting action is decentered with respect to the axial principal ray, and has a rotationally asymmetric surface shape having power. With such a configuration, it becomes possible to correct the eccentric aberration caused by giving power to the reflecting surface by the surface itself, and by relaxing the power of the refracting surface of the prism, the occurrence of chromatic aberration itself can be reduced. Can be smaller.

The rotationally asymmetric surface used in the present invention is preferably an anamorphic surface or a plane-symmetric free-form surface having only one plane of symmetry. Here, the free-form surface used in the present invention is defined by the following equation (a). Note that the Z axis of the definition formula is the axis of the free-form surface.

[0027] Here, the first term of the equation (a) is a spherical term, and the second term is a free-form surface term.

In the spherical term, c: curvature of the vertex k: conic constant (conical constant) r = √ (X ² + Y ² ).

The free-form surface term is Here, C _j (j is an integer of 2 or more) is a coefficient.

The free-form surface is generally an XZ surface,
Although neither YZ plane has a plane of symmetry, in the present invention, X
By setting all the odd-order terms of 0 to 0, the YZ plane and the flat
The free-form surface has only one line of symmetry plane. example
For example, in the above definition formula (a), C_Two, C_Five, C₇,
C₉, C₁₂, C₁₄, C₁₆, C₁₈, C₂₀, C_{twenty three}, C_{twenty five}, C
₂₇, C₂₉, C₃₁, C₃₃, C₃₅Set the coefficient of each term of ... to 0
It is possible by doing.

By setting all odd-numbered terms of Y to 0, a free-form surface having only one symmetry plane parallel to the XZ plane is obtained. For example, in the above definition formula, C ₃ ,
_{C 5, C 8, C 10} , C 12, C 14, C 17, C 19, C 21, C
₂₃ , C ₂₅ , C ₂₇ , C ₃₀ , C ₃₂ , C ₃₄ , C ₃₆ ...

One of the directions of the symmetry plane is a symmetry plane, and the eccentricity of the corresponding direction, for example, the eccentric direction of the optical system with respect to the symmetry plane parallel to the YZ plane is in the Y-axis direction. By making the eccentric direction of the optical system the X-axis direction with respect to the symmetric plane parallel to the XZ plane, it is possible to effectively correct rotationally asymmetric aberrations caused by the eccentricity while improving the productivity. Becomes possible.

Further, the above-mentioned definition expression (a) is shown as one example as described above, and the present invention uses a rotationally asymmetric surface having only one plane of symmetry to produce rotation caused by eccentricity. It is characterized by correcting asymmetric aberrations and at the same time improving productivity, and it goes without saying that the same effect can be obtained for any other definitional expressions.

Then, the see-through optical system is adjusted so that the combined optical power and angular magnification given when the light flux from the second image passes through the see-through optical element and the eyepiece optical system satisfy the following conditions. It is desirable that the optical power generated by the optical system be offset from the angular magnification.

-0.002 <Px <0.002 (1 / mm) (3) -0.002 <Py <0.002 (1 / mm) (4) 0.97 <βx <1.03 (5) 0.95 <βy <1.05 (6) However, the eccentric direction of all optical systems is the Y-axis direction, and the plane parallel to the axial principal ray is defined as Y− When the Z-plane is set and the direction orthogonal to the YZ-plane is set as the X-direction, the power of the whole system in the X-direction is Px,
The power in the Y direction is Py, the angular magnification of the whole system in the X direction is βx,
The angular magnification of the entire system in the Y direction is βx. However, when the human vertical direction is the Y-axis direction. When the human vertical direction is the X-axis direction, the conditions (5) and (6) are as follows.

0.95 <βx <1.05 (5) ′ 0.97 <βy <1.03 (6) ′ Here, the difference in angular magnification between the vertical direction and the horizontal direction is found. The reason is that the human eye can see the horizontal X more finely than the vertical Y, so that βy in the Y direction can be somewhat loose, so that there is a difference between the conditions (5) and (6). With.

The meanings of the upper and lower limits of the conditions (3) to (6) are the same as the meanings of the upper and lower limits of the conditions (1) and (2).

The power Px in the X direction and the power Py in the Y direction of the entire system are more preferably -0.001 <Px <0.001 (1 / mm) (3-1) -0.001 <Py <0.001 (1 / mm) (4-1) It is important to satisfy the following condition. -0.0005 <Px <0.0005 (1 / mm) (3-2) -0.0005 <Py <0.0005 (1 / mm) (4-2) It is desirable to satisfy at least one of the following.

The angular magnification βx of the whole system in the X direction and the angular magnification βx of the whole system in the Y direction are more preferably 0.99 <βx <1.01 (5-1) 0.99 <βy <1.01 (6-1) It is important to satisfy the following conditional expression.

More preferably, it is important to satisfy the following conditional expression: 0.995 <βx <1.005 (5-2) 0.995 <βy <1.005 (6-2) It is.

Next, the curvatures in the X and Y directions at the intersection of the incident surface and the visual axis (on-axis principal ray) in the reverse ray tracing of the first prism (the prism optical system 10 in FIG. 1) on the eye side are calculated. C
x1, Cy1, the curvatures in the X and Y directions at the intersection of the exit surface of the first prism with the visual axis are Cx2, Cy2, and at the intersection with the visual axis of the incident surface of the see-through optical element arranged on the object side. The curvature in the X and Y directions is Cx3,
Cy3, and the curvature of the exit surface of the see-through optical element is Cx
4, Cy4, when the first prism and the second prism are arranged close to each other, Cx3 / Cx2 and Cy3 / Cy
2 preferably satisfies the following condition.

0.3 <Cx3 / Cx2 <1.2 (7) 0.3 <Cy3 / Cy2 <1.2 (8) If the lower limit of 0.3 of the above conditional expression is exceeded, 0.3 If this portion has too much positive power due to the air layer sandwiched between the two surfaces, and the optical power of the entire system is set to 0, the exit surface of the second prism must be changed to cancel the power of this portion. It is inevitable to have a strong negative optical power, and the angular magnification is greatly reduced to 1 or less. On the other hand, when the angular magnification is set to approximately 1, similarly, the exit surface of the second prism is forced to have a strong negative optical power, and the entire optical power has a strong positive power, so that the user can observe a distant place. You will not be able to do it.

If the upper limit of 1.2 of the above conditional expression is exceeded, this portion will have too much negative power due to the air layer sandwiched between the above two surfaces. However, in order to cancel the power of this portion, the exit surface of the second prism must have a strong positive optical power, and the angular magnification becomes large and becomes 1 or more. On the other hand, when the angular magnification is set to 1, similarly, the exit surface of the second prism has to have a strong positive optical power, and the entire optical power has a strong negative power. Can not be done.

More preferably, it is necessary to satisfy the following condition: 0.4 <Cx3 / Cx2 <1 (7-1) 0.4 <Cy3 / Cy2 <1 (8-1) is there.

By the way, as shown in FIG. 1, the eyepiece optical system has a prism member sandwiching at least a medium having a refractive index larger than 1, and the prism member is at least one of a transmissive and a reflective optical member. Three or more optically active surfaces having an effect, the three surfaces being opposed to the third surface on which the light flux from the first image enters the prism and the see-through optical element at a distance from the third surface; A second surface configured to have a function of transmitting the light flux from the transmitted second image into the prism and a function of reflecting the light flux from the first image within the brhythm, and to have at least a curved reflecting surface; It is desirable that the first surface emits a light beam from the first image to the outside of the prism.

In this case, at least one of the first surface and the third surface has a rotationally asymmetric curved surface shape for correcting eccentric aberration, and the curved surface shape corresponds to an anamorphic surface or a symmetric surface. It is desirable to be configured as a plane-symmetric free-form surface having only one surface.

It is desirable that the first surface is configured to have both the function of reflecting and transmitting the light beam in the prism.

In this case, the surface for both reflection and transmission of the first surface is constituted by a total reflection surface such that a reflected light beam enters the first surface at an angle exceeding the critical angle for total reflection. Then, it is desirable that the reflected light flux reflected by the reflecting surface is made incident at an angle not exceeding the total reflection critical angle and emitted from the prism.

In the observation optical system of the present invention, the first
The first image observation visual field range determined by the light beam from the image emitted from the eyepiece optical system is determined, and the second image observation visual field is determined by the light beam from the second image transmitted through the see-through optical element and part of the eyepiece optical system. The eyepiece optical system and the see-through optical element may be configured to be formed within the range.

Also, a see-through optical element such that a light-beam transmitting area transmitted from the see-through optical element shifts toward the image forming member side with respect to a light-beam reflecting area of the reflecting surface arranged opposite to the see-through optical element of the eyepiece optical system. Optical diameter is smaller than the reflecting surface of the eyepiece optical system, and the see-through optical element is disposed so as to face a region of the reflecting surface close to the image forming member, and faces the see-through optical element of the reflecting surface. The portion not to be provided may be provided with a light-shielding coat for preventing the incidence of flare rays from the outside.

A light-shielding member capable of transmitting and blocking a light beam from an external image or switching between transmission and dimming is disposed at least in front of or behind the see-through optical element so that the second image is an external image. Can be configured.

Further, the display element is arranged on the side opposite to the eyepiece optical system of the see-through optical element so that the second image is formed by a display element forming an image different from the first image. You can also.

Further, a light-blocking member capable of transmitting and blocking a light beam from the external image or switching between transmission and dimming is disposed at least in front of or behind the see-through optical element so that the second image is an external image. And a display element for displaying the third image can be arranged between the external image and the see-through optical element.

In the observation optical system of the present invention, the first
An optical path in the eyepiece optical system that guides the light flux from the image and an optical path in the see-through optical element that guides the light flux from the second image are a light source for pupil irradiation arranged at a different position and an image of the pupil. A light receiving element for receiving light may be provided to detect the line of sight of the observer.

In this case, the means for detecting the line of sight is configured such that at least the image of the pupil passes through the optical path of the eyepiece optical system, is separated from the optical path between the first image, and is guided to the light receiving element. can do. In this way, by using the optical path of the line-of-sight detecting means also as the observation optical path, it is possible to eliminate the influence of external light that may enter from the optical path of the line-of-sight detecting means, stray light from the pupil irradiation light source, and the like. The system can be largely reduced, and the cost and size can be reduced.

Also, the optical axis of the light beam from the first image emitted from the eyepiece optical system is defined as the visual axis, and the eyepiece optical system is oriented around the exit pupil from the visual axis to the opposite side to the image forming member. Assuming that the angle is θ, it is desirable that the eyepiece optical system, the see-through optical element, and the exit pupil be arranged in a relationship satisfying the following condition.

Θ ≦ 60 ° If the arrangement satisfies this condition, besides the see-through optical path,
For example, it is possible to directly see the lower keyboard or the like without passing through the observation optical system.

The present invention is provided with any of the above-described observation optical systems, and the eyepiece optical system, the see-through optical element, and the image forming member for forming the first image are held by holding means for holding an interval. The head-mounted observation optical device includes a main body part provided and support means for supporting the main body part on the observer's head.

[0059]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments 1 and 2 of the observation optical system according to the present invention will be described below. These embodiments will be described with reference to the reverse ray tracing. However, as shown in FIG.
By arranging an image display element at the exit pupil 1 and arranging the pupil of the observer's eyeball at the position of the exit pupil 1, the image display element functions as a display image observation optical apparatus, and the prism optical system 10 of the eyepiece optical system and the see-through optical element 20 By observing the outside world from the exit pupil 1 through the camera, the outside world can be seen through. The configuration parameters of these embodiments will be described later.

In each embodiment, as shown in FIG. 1, the on-axis principal ray 2 exits the center of the object, passes through the center of the exit pupil 1, and
It is defined by a ray reaching the center of the image plane 3 or the center of the external world. Then, with the center of the pupil 1 as the origin of the optical surface constituting the observation optical system, the axial chief ray 2 incident on the first surface 11 of the observation optical system
Is defined as a positive direction of the Z axis, a plane including the Z axis and the center of the image plane is defined as a YZ plane, and a direction passing from the origin and orthogonal to the YZ plane and extending from the near side of the paper toward the back side is the X axis. An axis forming the right-handed orthogonal coordinate system with the X axis and the Z axis is defined as a Y axis. FIG. 1 shows a coordinate system defined for the origin.

In the first and second embodiments, the prism members 10 and 2 are positioned within the YZ plane of the coordinate system defined for the center of the pupil 1.
0 is decentered, and the only symmetrical plane of each rotationally asymmetric free-form surface is the YZ plane.

The eccentric surfaces of the prism members 10 and 20 are determined from the origin of the coordinate system defined with respect to the center of the pupil 1.
The amount of eccentricity at the top of the surface (X, Y, and Z in the X-, Y-, and Z-axis directions, respectively) and the central axis of the surface (for a free-form surface, the Z-axis For the aspherical surface, the inclination angles (α, β, γ (°), respectively) about the X axis, Y axis, and Z axis of the later-described formula (b) are given. In this case, the positive α and β mean counterclockwise with respect to the positive direction of each axis, and the positive γ means clockwise with respect to the positive direction of the Z axis.

In a case where a specific surface and a surface subsequent thereto constitute a coaxial optical system among the optical working surfaces constituting the optical system of each embodiment, a surface interval is given, and other media are provided. Are given according to the conventional method.

The shape of the surface of the free-form surface used in the present invention is defined by the above equation (a), and the Z axis of the definition expression is the axis of the free-form surface.

The aspherical surface is a rotationally symmetric aspherical surface given by the following definitional expression.

Z = (Y ² / R) / [1+ ｛1− (1 + K) Y ² / R ² ｝ ^1/2 ] + AY ⁴ + BY ⁶ + CY ⁸ + DY ¹⁰ +... (B) Is the optical axis (on-axis principal ray) where the traveling direction of light is positive, and Y is a direction perpendicular to the optical axis. Here, R is a paraxial radius of curvature, K is a conic constant, and A, B, C, D,... Are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively.
The Z axis of this definition expression is the axis of the rotationally symmetric aspherical surface.

Note that terms relating to free-form surfaces and aspheric surfaces for which no data is described are zero. Regarding the refractive index,
The values for the d-line (wavelength 587.56 nm) are shown. The unit of the length is mm.

As another definition of the free-form surface, there is a Zernike polynomial given by the following expression (c).
The shape of this surface is defined by the following equation. The Z axis of the defining equation is the axis of the Zernike polynomial. The definition of the rotationally asymmetric surface is defined by polar coordinates of the height of the Z axis with respect to the XY plane, A is the distance from the Z axis in the XY plane, R is the azimuth around the Z axis, and the Z axis It can be expressed by the rotation angle measured from.

[0069] x = R × cos (A) y = R × sin (A) Z = D 2 + D 3 Rcos (A) + D 4 Rsin (A) + D 5 R 2 cos (2A) + D 6 (R 2 -1 ^{_{) + D 7 R 2 sin (}} 2A) + D 8 R 3 cos (3A) + D 9 (3R 3 -2R) cos (A) + D 10 (3R 3 -2R) sin (A) + D 11 R 3 sin (3A) + D ^{_{12 R 4 cos (4A) +}} D 13 (4R 4 -3R 2) cos (2A) + D 14 (6R 4 -6R 2 +1) + D 15 (4R 4 -3R 2) sin (2A) + D 16 R 4 sin (4A ^{_{) + D 17 R 5 cos (}} 5A) + D 18 (5R 5 -4R 3) cos (3A) + D 19 (10R 5 -12R 3 + 3R) cos (A) + D 20 (10R 5 -12R 3 + 3R) sin (A) _{^{+ D 21 (5R 5 -4R 3}} ) sin (3A) + D 22 R 5 sin (5A) + D 23 R 6 cos (6A) + D 24 (6R 6 -5R 4) cos (4A) + D 25 (15R 6 -20R 4 ^{+ 6R 2) cos (2A)} + D 26 (20R 6 -30R 4 + 12R 2 -1) + D 27 (15R 6 -20R 4 + 6R 2) sin (2A) _{^{D 28 (6R 6 -5R 4)}} sin (4A) + D 29 R 6 sin (6A) ····· ··· (c) In addition, to design an optical system symmetric with respect to the X-axis direction, D
_{4, D 5, D 6,} D 10 0, D 11, D 12, D 13, D 14, D
_20, D _21, D ₂₂ ... to use.

As another example, the following definition formula (d)
Is raised.

Z = ΣΣC _nm XY As an example, if k = 7 (seventh-order term) is considered, when expanded, it can be expressed by the following equation.

Z = C ₂ + C ₃ Y + C ₄ | X | + C ₅ Y ² + C ₆ Y | X | + C ₇ X ² + C ₈ Y ³ + C ₉ Y ² | X | + C ₁₀ YX ² + C ₁₁ | X ³ | + C ₁₂ Y ⁴ + C ₁₃ Y ³ | X | + C ₁₄ Y ² X ² + C ₁₅ Y | X ³ | + C ₁₆ X ⁴ + C ₁₇ Y ⁵ + C ₁₈ Y ⁴ | X | + C ₁₉ Y ³ X ² + C ₂₀ Y ² | X ^{_{3 | + C 21 YX 4 +}} C 22 | X 5 | + C 23 Y 6 + C 24 Y 5 | X | + C 25 Y 4 X 2 + C 26 Y 3 | X 3 | + C 27 Y 2 X 4 + C 28 Y | X 5 | ^{_{+ C 29 X 6 + C 30}} Y 7 + C 31 Y 6 | X | + C 32 Y 5 X 2 + C 33 Y 4 | X 3 | + C 34 Y 3 X 4 + C 35 Y 2 | X 5 | + C 36 YX 6 + C 37 | X ⁷ | (d) In the embodiment of the present invention, the surface shape is represented by a free-form surface using the above equation (a).
It goes without saying that the same operation and effect can be obtained by using the equation (d).

As for the diffractive optical element, for example, “Small Optical Elements for Optical System Designers”, Chapters 6 and 7 (published by Optronics) and “SPIE” Chapter 12
6, p. 46-53 (1977), etc., where the Abbe number ν in the visible region is −3.453 and the partial dispersion ratio θ _{g, F is} 0.03, and the interval between the diffraction gratings can be freely changed. Therefore, it can be treated equivalent to an arbitrary aspheric lens surface. In the following, “SPIE” Vol. 126, p. 4
6-53 (1977).
"high index method" is used.

FIG. 1 is a YZ sectional view including the optical axis of the observation optical apparatus having the see-through optical system according to the first embodiment of the present invention. The observation optical device including the see-through optical system according to the second embodiment has the same configuration. The horizontal angle of view when observing the display image on the image plane of the observation optical device of these examples is 22 °, the size of the image display element is 9.6 × 7.2 mm, and the pupil diameter is 4 mm.

When observing the display image of the image display element, the observation optical apparatus uses an exit pupil 1, a prism optical system 10, a diffractive optical element 4, a parallel plane plate 6. It consists of the image plane 3, and when sheathing the external world, in the order of light passing from the object side by reverse ray tracing,
Exit pupil 1, prism optical system 10, see-through optical element 2
Consists of zero.

The prism optical system 10 is composed of a first surface 11 to a third surface 13 for back ray tracing. The first surface 11 allows a light beam from the object side to enter the prism 10 and a second surface 12. The second surface 12 serves as both a transmission surface for totally reflecting the reflected light flux in the prism and a total reflection surface.
Is a semi-transmissive reflection surface that reflects the light beam incident from the first surface 11 in the prism and partially transmits the light beam to the see-through optical element 20 side. The third surface 13 is a light beam reflected by the first surface 11. Is transmitted out of the prism.

The surface on the image plane 3 side of the diffractive optical element 4 is a diffractive surface 5. The parallel plane plate 6 constitutes an optical system or filters for illuminating the image plane 3.

The display light from the display surface of the image display device arranged on the image plane 3 is diffracted by the diffraction surface 5 of the diffractive optical element 4 via the plane-parallel plate 6 and the third surface 13 of the prism optical system 10.
Enters the prism from the first surface 11, is totally reflected by the first surface 11,
The light is reflected by the surface 12 and then refracted by the first surface 11 and exits the prism. The light enters the observer's eyeball where the pupil is located at the exit pupil 1, and an enlarged image of the display image of the image display element is displayed. Form.

The see-through optical element 20 is disposed at an interval in front of the third surface 13 of the prism optical system 10, and is formed of a first prism 21 and a second prism 22 by back ray tracing. The light from the outside passes through the second surface 22, the first surface 21, the second surface 12, and the first surface 11 of the see-through optical element 20 in this order, and passes through the pupil at the position of the exit pupil 1. Is incident on the observer's eyeball at which is located, and forms an external image. The external image and the display image on the image plane 3 are observed selectively or superimposed.

FIG. 2 is a YZ sectional view including the optical axis of the see-through optical system according to the first embodiment, and FIG. 3 is a YZ sectional view including the optical axis of the see-through optical system according to the second embodiment. The prism optical system 10 of both embodiments is common, and the surface shape of the see-through optical element 20 is different.
It is disposed in front of the surface 13 and comprises a transmission prism member composed of a first surface 21 and a second surface 22 for back ray tracing.

Hereinafter, the structural parameters of the see-through optical system in each of the above embodiments and the structural parameters of the observation optical system of the image display device arranged on the image plane 3 common to both embodiments will be described.
In the following table, "FFS" is a free-form surface, "ASS" is an aspheric surface, "DOE" is a diffraction surface, "LCD" is a display surface of an image display element, "RS" is a reflection surface, and "HRP" is a virtual surface. Are respectively shown.

(Example 1) Surface number Curvature radius Surface distance Eccentricity Refractive index Abbe number Object plane ∞ ∞ 1 ∞ (pupil) 2 ASS Eccentricity (1) 1.5254 56.2 3 FFS Eccentricity (2) 4 FFS Eccentricity (3) 1.5254 56.2 5 ASS Eccentricity (4) ASS R -176.22 K -3.7387 × 10 ⁺¹ A -1.6692 × 10 ^-6 B 2.9814 × 10 ^-9 C -2.0018 × 10 ^-12 ASS R -1062.55 K 5.4556 × 10 ⁺² A 3.6429 × 10 ^-6 B 5.0 316 × 10 ^-9 C -1.1192 × 10 ^-12 FFS C ₄ -6.8800 × 10 ^-3 C ₆ -6.3619 × 10 ^-3 C ₈ 4.1553 × 10 ^-5 C ₁₀ 6.8837 × 10 ^-5 C ₁₁ 1.2241 × 10 ^-6 C ₁₃ 3.3302 × 10 ^-6 C ₁₅ 2.5098 × 10 ^-6 C ₁₇ 3.8987 × 10 ^-8 C ₁₉ 1.2588 × 10 ^-7 C ₂₁ 5.2527 × 10 ^-8 FFS C ₄ -4.4 160 × 10 ^-3 C ₆ -2.4845 × 10 ^-3 C ₈ 2.2623 × 10 ^-4 C ₁₀ 2.3442 × 10 ^-4 C ₁₁ 8.6043 × 10 ^-6 C ₁₃ 1.7297 × 10 ^-5 C ₁₅ 9.4774 × 10 ^-6 C ₁₇ 8.8 375 × 10 ^-8 C ₁₉ 2.5550 × 10 ^-7 C ₂₁ 1.6464 × 10 ^-7 Eccentricity (1) X 0.00 Y -2.61 Z 32.27 α 5.50 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 3.08 Z 42.45 α -14.95 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y 3.08 Z 42.95 α -14.95 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y -6.46 Z 48.00 α 7.60 β 0.00 γ 0.00.

(Example 2) Surface number Curvature radius Surface distance Eccentricity Refractive index Abbe number Object plane ∞ ∞ 1 ∞ (pupil) Eccentricity (1) 2 ASS Eccentricity (2) 1.5254 56.2 3 FFS Eccentricity (3) 4 FFS Eccentricity ( 4) 1.5254 56.2 5 FFS Eccentricity (5) ASS R -176.22 K -3.7387 × 10 ⁺¹ A -1.6692 × 10 ^-6 B 2.9814 × 10 ^-9 C -2.0018 × 10 ^-12 FFS C ₄ -6.8800 × 10 ^-3 C ₆ -6.3619 × 10 ^-3 C ₈ 4.1553 × 10 ^-5 C ₁₀ 6.8837 × 10 ^-5 C ₁₁ 1.2241 × 10 ^-6 C ₁₃ 3.3302 × 10 ^-6 C ₁₅ 2.5098 × 10 ^-6 C ₁₇ 3.8987 × 10 ^-8 C ₁₉ 1.2588 × 10 ^-7 C ₂₁ 5.2527 × 10 ^-8 FFS C ₄ -5.3827 × 10 ^-3 C ₆ -3.9 107 × 10 ^-3 C ₈ 2.0464 × 10 ^-5 C ₁₀ 2.0013 × 10 ^-4 C ₁₁ -3.0583 × 10 ^-6 C ₁₃ 2.9474 × 10 ^-6 C ₁₅ 5.4444 × 10 ^-6 C ₁₇ -1.1451 × 10 ^-7 C ₁₉ 1.3958 × 10 ^-7 C ₂₁ 3.3195 × 10 ^-7 FFS C ₄ -3.9314 × 10 ^-4 C _{6 ^{4.9360 × 10 -4 C 8 -9.7487 ×}} 10 -6 C 10 1.6818 × 10 -4 C 11 -5.3888 × 10 -6 C 13 -2.1876 × 10 -6 C 15 5.8586 × 10 -6 C 17 -7.0891 × 10 - ⁸ C ₁₉ -4.0581 × 10 ^-8 C ₂₁ 3.4163 × 10 ^-7 Eccentricity (1) X 0.00 Y -2.61 Z 32.27 α 5.50 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 3.08 Z 42.45 α -14.95 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y 1.38 Z 42.12 α -14.16 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y 1.25 Z 47.68 α 9.11 β 0.00 γ 0.00.

(Observation optical system of image display element) Surface number Radius of curvature Surface spacing Eccentricity Refractive index Abbe number Object plane -100-1000.00 1 ∞ (pupil) 2 ASS Eccentricity (1) 1.5254 56.2 3 FFS (RS) Eccentricity (2) 1.5254 56.2 4 ASS (RS) Eccentricity (1) 1.5254 56.2 5 FFS Eccentricity (3) 6 ∞ (HRP) 1.50 Eccentricity (4) 7 ∞ 1.40 1.5254 56.2 8 ∞ 0.00 1001.0682 -3.5 9 -209 750.722 (DOE) 0.50 10 ∞ 7.13 1.5163 64.1 11 ∞ 1.56 12 ∞ 0.16 1.5860 34.5 13 ∞ 1.10 1.5230 59.4 Image plane ∞ (LCD) ASS R -176.22 K -3.7387 × 10 ⁺¹ A -1.6692 × 10 ^-6 B 2.9814 × 10 ^-9 C -2.0018 × 10 ^-12 FFS C ₄ -6.8800 × 10 ^-3 C ₆ -6.3619 × 10 ^-3 C ₈ 4.1553 × 10 ^-5 C ₁₀ 6.8837 × 10 ^-5 C ₁₁ 1.2241 × 10 ^-6 C ₁₃ 3.3302 × 10 ^-6 C ₁₅ 2.5098 × 10 ^-6 C ₁₇ 3.8987 × 10 ^-8 C ₁₉ 1.2588 × 10 ^-7 C ₂₁ 5.2527 × 10 ^-8 FFS C ₄ -2.3155 × 10 ^-2 C ₆ -3.0035 × 10 ^-2 C ₈ 4.7893 × 10 ^-4 C ₁₀ 5.9 168 × 10 ^-4 C ₁₁ 7.4 760 × 10 ^-6 C ₁₃ 4.6 108 × 10 ^-5 C ₁₅ 1.6986 × 10 ^-5 C ₁₇ -7.6840 × 10 ^-7 C ₁₉ -3.8926 × 10 ^-6 C ₂₁ -2.0872 × 10 ^-6 Eccentricity (1) X 0.00 Y -2.61 Z 32.27 α 5.50 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 3.08 Z 42.45 α -14.95 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y 18.35 Z 39.28 α 60.78 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y 18.86 Z 38.29 α 49.61 β 0.00 γ 0.00.

FIGS. 4 and 5 are diagrams in which the grid image viewed through the see-through optical system of the first and second embodiments and the grid image viewed with the naked eye are superimposed, respectively. When the observation optical system of each embodiment is used in a head-mounted observation optical device of a one-eye type, observing the external world with both eyes reveals that the external image can be easily fused with the left and right eyes. It is.

The conditions (3) to (5) of the first and second embodiments were used.
Px, Py, βx, βy, Cx3 / Cx for (8)
2, the values of Cy3 / Cy2 are as follows.

Px Py βx βy Cx3 / Cx2 Cy3 / Cy2 Example 1 0.00050 0.00000 0.99920 0.99850 0.69950 0.56645 Example 2 0.00060 -0.00010 0.99691 1.00130 0.83012 0.62687

Next, FIG. 6 shows the configuration of an observation optical system according to another embodiment of the present invention. Reflective LCD (Liquid Crystal Display) 10
0, illumination light source 101, illumination optical elements 102, 10
And an eyepiece optical system 10 for guiding the first image displayed on the reflective LCD 100 to the observer's eyeball E.
And an eyepiece optical system 104 for guiding an external image (second image)
A see-through optical element 105 disposed on the second image side of
Further, the observation optical system of the present embodiment is formed by a configuration including the light shielding member 106 disposed on the second image side and capable of switching between transmission and blocking of light beams or switching between transmission and light reduction. Further, for sight line detection, the pupil illumination light source 107
And a light receiving element 108 for receiving the pupil image, and a CPU 109 for analyzing the pupil image of the light receiving element 108 and controlling other members based on the information.

The illumination light source 101 is an LED, a lamp or the like, and may be a white light source or an R, G, B set light source. The illumination optical element 102 has a convex surface 110 having a positive power on the light source 101 side, and has a function of a field lens. In addition, from the viewpoint of harmony between the demand for correcting the generated aberration and the demand for cost reduction by improving productivity, the convex surface 110 is changed from a spherical surface to a rotationally symmetric aspherical surface and an analogy. It is desirable to change to a morphic surface or a free-form surface in order to increase the degree of freedom of design, and conversely, if the demand for cost reduction increases, it is desirable to change to a spherical surface or a rotationally symmetric aspheric surface with high productivity. Illumination optical elements 102 and 1
A half mirror coat, a beam split coat, and the like are formed on the surface 111 between the first and third surfaces so as to have both a light transmission function and a light reflection function. Also, in the case where the pupil illumination light source 107 for field of view detection is light having a narrow wavelength band even in the infrared light or visible light region, even if the light is reflected, L
Since the influence on the observation of the first image from the CD 100 can be ignored, the surface 111 during this time may be a surface having wavelength selectivity that reflects the light of the light source 107 with high reflectance.

The eyepiece optical system 104 includes a first surface 112, a second surface
It is composed of a prism having three optically active surfaces, a surface 113 and a third surface 114, and light incident from the third surface 114 is
Totally reflected on the first surface 112 and reflected on the second surface 113,
This time, an exit pupil is formed through the first surface 112, and when the observer places the pupil of the eyeball there, the display image of the LCD 100 can be observed. These three faces 112
Since 〜114 are eccentrically arranged, it is desirable to configure them with an anamorphic surface or a free-form surface capable of correcting eccentric aberration (especially, a free-form surface whose cross section in FIG. 6 is the only symmetrical surface). However, in order to achieve harmony from the viewpoint of productivity, it is desirable that at least one of the first to third surfaces 112 to 114 is formed of a rotationally symmetric aspherical surface or a spherical surface. At this time, if attention is paid to the accuracy of the surface, the surface area is the widest, and the first surface 112, which acts twice on the light beam by transmission and reflection, can be formed into a spherical surface or a rotationally symmetric aspheric surface capable of ensuring high production accuracy. Is desirable. Further, the eyepiece optical system 10
If attention is paid to aberration performance, power, and the like due to an air lens between the second surface 113 and the see-through optical element 105, the second surface 113
Is preferably a spherical surface or a rotationally symmetric aspheric surface.

The light-blocking member 106 capable of switching between transmission and blocking of light flux or switching between transmission and dimming includes a shutter (mechanical aperture shutter, liquid crystal shutter, blind shutter) or a lid capable of switching between transmission and blocking of light. In addition to a simple door mechanism that only opens and closes, a liquid crystal plate or the like configured so that the transmittance changes stepwise or continuously may be used. The light shielding member 106 measures the size of the pupil from the pupil image received by the light receiving element 108, for example.
The CPU 109 controls so as to adjust the brightness when the opening is larger than a certain value, and to adjust the brightness when the opening is smaller than a certain value. In addition, external image and LCD1
The difference in illuminance from the display image of 00 may be measured by a measuring device (not shown), and the transmittance of the light blocking member 106 may be controlled by the CPU 109 according to the measured value.

Further, using the information detected by the line of sight, L
The image displayed on the CD 100 can be scrolled or can have the same effect as a cursor displayed on a computer screen.

Also, the second surface 113 of the eyepiece optical hand system 104
If the size of the see-through optical system element 105 is the same as that of the see-through optical system element 105, assembly becomes easy. Conversely, when the see-through optical element 105 is reduced in size for weight reduction, it is desirable to provide a light-shielding coat 115 such as a light-shielding paint or coating on the optical surface or side surface to prevent flare.

FIG. 7 shows a modification of the embodiment shown in FIG. This is because, for example, when an image of a computer screen is displayed on the LCD 100 (a transmissive LCD or a reflective LCD can be used), the see-through optical element 1 can be used such that the user can easily look down the keyboard with his / her eyes down.
This shows a configuration in which an external image below can be directly viewed in addition to the external image through the external device 05. In order to secure the lower visual field in this way, the eyepiece optical system 104 and the see-through optical element 105 are housed within 60 ° (θ ≦ 60 °) around the pupil center with respect to the visual axis. As described above, it is preferable that the distance between the pupil and the eyepiece optical system 104 is increased or the length below the pupil is shortened. However, in the case where the angle is limited due to a vertical angle of view or a requirement in optical design, the angle may be set to 45 ° or less (θ ≦ 45 °) from the viewpoint of harmonization between the two.

As another form, as shown in FIG. 8, a third image different from the external image is displayed on the see-through optical element 1.
05 and the eyepiece optical system 104 to guide to the pupil E. A display element 11 for displaying small characters, such as an LCD, an LED, or a symbol display using external light.
6 is disposed outside the see-through optical element 105. When displaying the image of the display element 116 on the external visual field, the display element 116 is arranged between the light shielding member 106 and the see-through optical element 105. The external image and the display element 11
When the images 6 are arranged side by side, as shown in FIG.
06 is shortened, and the display element 116 is provided at that position. In this case, in order to prevent the incidence of flare light or the like while making the boundary portion clear, a light shielding coat 11
5 is desirably provided. This display element 116 includes
It can be used for warning display, display of measurement values of an outside temperature / humidity sensor, an ultraviolet ray amount measurement sensor, and the like (not shown), and display of support information such as display of use time and time.

Further, when the field of view of the external image may be narrow, or when there is a strong demand for making the entire device compact and lightweight, as shown in FIGS. You may comprise. In the case of FIG. 9, the see-through optical element 105 is disposed below and the LCD 100
Since the visual axis for observing the image from the outside and the visual axis for observing the image from the outside world substantially match, the observer can observe both images without turning the eyeball.

Further, in the case of FIG. 10, the see-through optical element 105 is disposed above and the image from the LCD 100 and the external image can partially overlap or be completely arranged side by side. Therefore, the image of the LCD 100 and the external image can be simultaneously observed.

In FIGS. 9 and 10, the see-through optical element 105 is arranged in the vertical direction, but may be arranged in the horizontal direction. 6 to 10 are longitudinal sectional views showing the LCD 1
00 are all arranged on the upper side, but the LCD 100 may be arranged on the lower side by rotating by 180 °.
Further, the observation optical system may be configured such that it is further rotated by 90 ° to form an optical path that is turned back from the lateral direction.

Although the eyepiece optical system 104 uses a prism with three optical action surfaces and a double reflection type, a prism of the type shown in FIGS. 11 to 17 may be used. . Further, the see-through optical element 105 is not limited to a single optical element, but may also be a bonded optical element or GRIN.
(Refractive index distribution) An optical element may be used.

The eyepiece optical system 1 shown in FIGS.
04 will be described briefly.

In the case of FIG. 11, the eyepiece optical system 104 is
The light which has the surface 11, the second surface 12, the third surface 13, and the fourth surface 14, and which has entered through the exit pupil position E in the reverse ray tracing,
The light is refracted on the first surface 11 and enters the prism, and the second surface 12
, Is internally reflected by the third surface 13, is incident on the fourth surface 14, is refracted, and forms an image at the position of the LCD 100.
In the case of the eyepiece optical system 104, the see-through optical element 105 is disposed on the second surface 12 on the side of the external image, away from the second surface 12.

In the case of FIG. 12, the eyepiece optical system 104 is the first
The light which has the surface 11, the second surface 12, the third surface 13, and the fourth surface 14, and which has entered through the exit pupil position E in the reverse ray tracing,
The light is refracted on the first surface 11 and enters the prism, and the second surface 12
Internally reflected, incident on the third surface 14 and totally reflected, incident on the fourth surface 14 and internally reflected, again incident on the third surface 13 and then refracted to form an image at the position of the LCD 100 I do. In the case of the eyepiece optical system 104, the see-through optical element 105 is disposed on the second surface 12 on the side of the external image, away from the second surface 12.

In the case of FIG. 13, the eyepiece optical system 104 is
The light which has the surface 11, the second surface 12, the third surface 13, and the fourth surface 14, and which has entered through the exit pupil position E in the reverse ray tracing,
The light is refracted on the first surface 11 and enters the prism, and the second surface 12
Internally reflected at the third surface 13 and internally reflected,
The light enters the surface 12 again, is internally reflected, is incident on the fourth surface 14, is refracted, and forms an image at the position of the LCD 100. In the case of the eyepiece optical system 104, the see-through optical element 105 is disposed on the second surface 12 on the side of the external image, away from the second surface 12.

In the case of FIG. 14, the eyepiece optical system 104 is the first
The light which has the surface 11, the second surface 12, the third surface 13, and the fourth surface 14, and which has entered through the exit pupil position E in the reverse ray tracing,
The light is refracted on the first surface 11 and enters the prism, and the second surface 12
Internally reflected at the third surface 13 and internally reflected,
The light is again incident on the surface 12 and is internally reflected, is incident on the fourth surface 15 and is internally reflected, is again incident on the second surface 12 and is refracted, and forms an image at the position of the LCD 100. In the case of the eyepiece optical system 104, the see-through optical element 105 is disposed on the second surface 12 on the side of the external image, away from the second surface 12.

In the case of FIG. 15, the eyepiece optical system 104 is the first
The surface 11, the second surface 12, and the third surface 13, and the light incident through the exit pupil position E in the reverse ray tracing is refracted on the first surface 11 and enters the prism, and the light is internally reflected on the second surface 12. Reflected
The light again enters the first surface 11 and is totally reflected this time, and the third surface 13
Internally reflected, incident on the first surface 11 three times and totally reflected,
The light enters the third surface 13 again and is refracted this time.
An image is formed at the position of 00. In the case of the eyepiece optical system 104, the see-through optical element 105 is provided on the external image side of the second surface 12.
Are spaced apart. Or alternatively, or
In addition, another see-through optical element 105 ′ may be arranged on the third surface 13 on the external image side.

In the case of FIG. 16, the eyepiece optical system 104 is
The surface 11, the second surface 12, and the third surface 13, and the light incident through the exit pupil position E in the reverse ray tracing is refracted on the first surface 11 and enters the prism, and the light is internally reflected on the second surface 12. Reflected
The light again enters the first surface 11 and is totally reflected this time, and the third surface 13
Internally reflected, incident on the first surface 11 three times and totally reflected,
The light enters the third surface 13 again, is internally reflected, and once again becomes the first surface 1
1 and is refracted to form an image at the position of the LCD 100. In the case of the eyepiece optical system 104, the second surface 1
The see-through optical element 105 is disposed on the side of the outside world image 2 at a distance. Alternatively, in addition to or in addition to this, another see-through optical element 1 is provided on the external image side of the third surface 13.
05 ′ may be placed apart.

In the case of FIG. 17, the eyepiece optical system 104 is the first
The light which has the surface 11, the second surface 12, the third surface 13, and the fourth surface 14, and which has entered through the exit pupil position E in the reverse ray tracing,
The light is refracted on the first surface 11 and enters the prism, and the second surface 12
Internally reflected at the third surface 14 and reflected by the fourth surface 1
4, is refracted and forms an image at the position of the LCD 100. In the case of the eyepiece optical system 104, the see-through optical element 105 is disposed on the second surface 12 on the side of the external image, away from the second surface 12.

The observation optical system according to the present invention as described above,
For example, it can be used as an optical system of a head mounted image display device. An example is shown below.

First, FIG. 18 shows a state in which the head-mounted image display device for one eye mounting is mounted on the observer's head, and FIG. 19 is a sectional view of the image display device. In this configuration, for example, an observation optical system as shown in FIG. 6 is used, and a display device main body 122 composed of one set including the observation optical system and the reflection type image display element 100 is connected to a corresponding eye of the front frame 128. (In this case, the left eye), it is mounted as a portable image display device such as a stationary or head mounted image display device that can be observed with one eye.

That is, the display device main body 122 uses the above-described observation optical system, and the reflection type image display device 100 composed of a reflection type liquid crystal display device is arranged on the image plane. As shown in FIG. 18, a temporal frame 123 is continuously provided on the left and right sides of the front frame 128 to which the display device main body 122 is attached so that the display device main body 122 can be held in front of the observer. Has become. In order to protect the first surface 112 of the eyepiece optical system 104 of the observation optical system of the image display device 122, a cover member is provided between the exit pupil of the eyepiece optical system 104 and the first surface 112 as shown in FIG. 121 are arranged. As the cover member 121, any of a parallel plane plate, a positive lens, and a negative lens may be used.

The speaker 1 is provided on the temporal frame 123.
24 is provided so that stereoscopic sound can be heard together with image observation. Thus, the speaker 1
Since the playback device 126 such as a portable video cassette is connected to the display device main body 122 having the display device 24 via the video / audio transmission cord 125, the viewer can attach the playback device 126 to an arbitrary portion such as a belt as shown in the drawing. , So that the user can enjoy video and audio. Reference numeral 127 in FIG.
This is an adjustment unit for adjusting the volume and the like. The display device body 12
2, electronic components such as a video processing circuit and an audio processing circuit are incorporated.

The cord 125 may have a jack at the tip so that it can be attached to an existing video deck or the like. 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.

Further, the observation optical system according to the present invention may be used in a head-mounted image display device for binocular mounting. FIG.
0 shows a state where the image display device for binocular mounting is mounted on the observer's head. In this configuration, a pair of left and right image display devices 122 including an observation optical system and the reflection type image display device 100 as shown in FIG. 19 are prepared, and they are supported at a distance from each other, so that observation can be performed with both eyes. It is configured as a portable image display device such as a stationary or head mounted image display device. Other configurations are shown in FIG.
8 and the description is omitted.

The observation optical system of the present invention and the observation optical device using the same can be configured as follows.

[1] An image forming member for forming a first image to be observed by an observer, an eyepiece optical system configured to guide an image formed by the image forming member to an observer's eyeball,
In an observation optical system including a see-through optical element arranged closer to the second image than the eyepiece optical system so as to guide a second image different from the image to the observer's eyeball, the eyepiece optical system includes:
In order to reflect the light beam from the first image and guide the light beam to the observer's eyeball side, the device has at least a curved reflecting surface, and the reflecting surface transmits the light beam from the second image transmitted through the see-through optical element. The see-through optical element is configured to have a function of transmitting light, and the see-through optical element is closer to the second image side than the reflection surface.
The optical power of the combination of the see-through optical element and the eyepiece optical system when the light flux from the second image passes through the see-through optical element and the eyepiece optical system and is spaced apart from the reflection surface. An observation optical system, wherein P is substantially 0 and the angular magnification β is substantially 1.

[2] The reflecting surface of the eyepiece optical system is configured to have a rotationally asymmetric curved surface shape for correcting eccentric aberration, and the light flux from the second image passes through the see-through optical element and the eyepiece optical system. The see-through optical system is configured to cancel out the optical power and the angular magnification generated in the eyepiece optical system so that the combined optical power and angular magnification given when the light passes therethrough satisfy the following conditions. 2. The observation optical system according to 1 above, wherein:

-0.002 <Px <0.002 (3) -0.002 <Py <0.002 (4) 0.97 <βx <1.03 (5) 0.95 <βy <1.05 (6) However, the eccentric direction of the entire optical system is the Y-axis direction, and a plane parallel to the axial principal ray is a YZ plane, and the YZ plane is Assuming that the orthogonal direction is the X direction, the power of the whole system in the X direction is Px,
The power in the Y direction is Py, the angular magnification of the whole system in the X direction is βx,
The angular magnification of the entire system in the Y direction is βx.

[3] The reflecting surface of the eyepiece optical system has a rotationally asymmetric curved surface shape for correcting eccentric aberration, and the curved surface shape has only one anamorphic surface or symmetric surface. 3. The observation optical system according to the above 1 or 2, wherein the observation optical system is constituted by a plane-symmetric free-form surface.

[4] The eyepiece optical system has a prism member sandwiching at least a medium having a refractive index greater than 1 and the prism member has at least one of an optical function of transmission or reflection. And three or more
The three surfaces face the light flux from the first image into the prism and the light flux from the second image transmitted through the see-through optical element while being opposed to the see-through optical element at an interval. And a function of reflecting the luminous flux from the first image within the brhythm, and a second surface having at least a curved reflecting surface, and a luminous flux from the first image. First out of the prism
4. The observation optical system according to any one of the above items 1 to 3, wherein the observation optical system is constituted by a surface.

[5] The third surface has a rotationally asymmetric curved surface shape for correcting eccentric aberration, and the curved surface shape is an anamorphic surface or a plane symmetric free surface having only one symmetric surface. The observation optical system according to any one of the above items 1 to 4, wherein the observation optical system is configured by a curved surface.

[6] The first surface has a rotationally asymmetric curved surface shape for correcting eccentric aberration, and the curved surface shape has an anamorphic surface or a plane symmetric free surface having only one symmetric surface. 6. The observation optical system according to any one of 1 to 5, wherein the observation optical system is configured by a curved surface.

[7] The observation optical system according to the above item 6, wherein the first surface is configured to have both a reflection function and a transmission function of a light beam in the prism.

[8] The surface of the first surface which is used for both the reflection function and the transmission function is a total reflection surface such that the reflected light beam enters the first surface at an angle exceeding the critical angle for total reflection. 8. The observation optical system according to claim 7, wherein the reflected light flux reflected by the reflecting surface is made incident at an angle not exceeding the critical angle for total reflection and emitted from the prism.

[0124]

[9] The first image observation visual field range determined by the light beam from the first image being emitted from the eyepiece optical system is such that the light beam from the second image passes through the see-through optical element and a part of the eyepiece optical system. 9. The eyepiece optical system and the see-through optical element are formed so as to be formed within a second image observation visual field range determined by transmission. Observation optical system.

[10] With respect to the light beam reflection area of the reflection surface of the eyepiece optical system facing the see-through optical element, the light beam transmission area transmitted from the see-through optical element shifts toward the image forming member. The optical diameter of the see-through optical element is configured to be smaller than the reflection surface of the eyepiece optical system, and the see-through optical element is arranged to face a region of the reflection surface closer to the image forming member, 9. The observation optics according to any one of the above items 1 to 8, wherein a portion of the reflection surface that does not face the see-through optical element is provided with a light-shielding coat for preventing the incidence of flare rays from the outside. system.

[11] A light-shielding member capable of transmitting and blocking a light beam from an external image or switching between transmission and dimming on at least one of the front and rear sides of the see-through optical element so that the second image is an external image. 11. The observation optical system according to any one of the above items 1 to 10, wherein the observation optical system is configured by disposing.

[12] The second image is formed by a display element forming an image different from the first image.
11. The observation optical system according to any one of the above items 1 to 10, wherein a display element is arranged on a side of the see-through optical element opposite to the eyepiece optical system.

[13] A light-shielding member capable of transmitting and blocking a light beam from an external image or switching between transmission and dimming at least one of the front and rear of the see-through optical element so that the second image is an external image. 11. The observation according to any one of the above items 1 to 10, wherein a display element for displaying a third image is disposed between the external image and the see-through optical element. Optical system.

[14] The optical path in the eyepiece optical system for guiding the light beam from the first image and the optical path in the see-through optical element for guiding the light beam from the second image are arranged at different positions. The observation optical system according to any one of the above items 1 to 13, comprising a light source for pupil irradiation, and a light receiving element for receiving an image of the pupil, and configured to detect a line of sight of an observer. system.

[15] The means for detecting the line of sight is such that at least the image of the pupil passes through the optical path of the eyepiece optical system, is separated from the optical path between the first image, and is guided to the light receiving element. 15. The observation optical system according to the above 14, wherein the observation optical system is configured to be moved.

[16] The optical axis of the light beam from the first image emitted from the eyepiece optical system is set as the visual axis, and the direction of the direction from the visual axis to the opposite side to the image forming member from the visual axis with the exit pupil as the center is described. Assuming that the angle defined by the eyepiece optical system is θ, the eyepiece optical system, the see-through optical element, and the exit pupil are arranged in a relationship satisfying the following condition. The observation optical system according to claim 1.

Θ ≦ 60 ° [17] The observation optical system according to any one of 1 to 15 above, wherein the eyepiece optical system, the see-through optical element, and the image forming member that forms the first image are spaced from each other. A head-mounted observation optical device, comprising: a main body held by holding means for holding the main body; and support means for supporting the main body on an observer's head.

[0133]

As is apparent from the above description, according to the present invention, the optical power P of the see-through optical system consisting of the see-through optical element and the eyepiece optical system constituting the observation optical system.
To approximately 0 and the angular magnification β to approximately 1, the image seen through the see-through optical system becomes the same as the image seen with the naked eye, and the image seen with the naked eye and the image seen through the see-through optical system Is easily fused, and for example, an external image can be easily observed with both eyes in a head mounted image display device of a single eye type.

[Brief description of the drawings]

FIG. 1 is an optical path diagram of an observation optical system according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a see-through optical system portion of the observation optical system according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a see-through optical system portion of an observation optical system according to a second embodiment of the present invention.

FIG. 4 is a diagram in which a grid image viewed through the see-through optical system of Example 1 and a grid image viewed with the naked eye are superimposed.

FIG. 5 is a diagram in which a grid image viewed through the see-through optical system of Example 2 and a grid image viewed with the naked eye are superimposed.

FIG. 6 is a diagram illustrating a configuration of an observation optical system according to another embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a modification of the embodiment of FIG. 6;

FIG. 8 is a diagram illustrating a configuration of an observation optical system according to another embodiment.

FIG. 9 is a diagram showing a configuration of an observation optical system of another embodiment.

FIG. 10 is a diagram illustrating a configuration of an observation optical system according to still another embodiment.

FIG. 11 is a diagram showing an example of an eccentric prism applicable to the eyepiece optical system of the observation optical system according to the present invention.

FIG. 12 is a diagram showing another example of an eccentric prism applicable to the eyepiece optical system of the observation optical system of the present invention.

FIG. 13 is a diagram showing another example of an eccentric prism applicable to the eyepiece optical system of the observation optical system of the present invention.

FIG. 14 is a diagram showing another example of an eccentric prism applicable to the eyepiece optical system of the observation optical system of the present invention.

FIG. 15 is a diagram showing another example of an eccentric prism applicable to the eyepiece optical system of the observation optical system of the present invention.

FIG. 16 is a diagram showing another example of the decentered prism applicable to the eyepiece optical system of the observation optical system of the present invention.

FIG. 17 is a diagram showing another example of an eccentric prism applicable to the eyepiece optical system of the observation optical system of the present invention.

FIG. 18 is a diagram showing a state in which a head-mounted image display device for one eye mounting using the observation optical system of the present invention is mounted on the observer's head.

19 is a sectional view of the image display device of FIG.

FIG. 20 is a diagram showing a state in which a head-mounted binocular image display device using the observation optical system of the present invention is mounted on the observer's head.

FIG. 21 is a conceptual diagram for explaining field curvature generated by an eccentric reflecting surface.

FIG. 22 is a conceptual diagram for explaining astigmatism generated by a decentered reflecting surface.

FIG. 23 is a conceptual diagram for explaining coma generated by a decentered reflecting surface.

[Explanation of symbols]

 E: observer's eyeball M: concave mirror 1: exit pupil 2: axial chief ray (optical axis) 3: image plane 4: diffractive optical element 5: diffractive surface 6: parallel plane plate 10: prism optical system 11: first surface DESCRIPTION OF SYMBOLS 12 ... 2nd surface 13 ... 3rd surface 14 ... 4th surface 20 ... See-through optical element 21 ... 1st surface 22 ... 2nd surface 100 ... LCD (liquid crystal display element) 101 ... Illumination light source 102, 103 ... Illumination optical element 104 eyepiece optical system 105 see-through optical element 106 light blocking member 107 pupil illumination light source 108 light receiving element 109 CPU 110 convex surface 111 surface between illumination optical elements 112 first surface of eyepiece optical system 113 eyepiece Second surface of optical system 114 Third surface of eyepiece optical system 115 Light shielding coat 116 Display element 121 Cover member 122 Display body 123 Temporal frame 124 Speaker 125 Image Voice transmission code 126 ... playback device 127 ... modulating portion 128 ... front frame

Claims (3)

[Claims] An image forming member for forming a first image to be observed by an observer; an eyepiece optical system configured to guide an image formed by the image forming member to an observer's eyeball; A see-through optical element disposed closer to the second image side than the eyepiece optical system so as to guide another second image to the observer's eyeball, wherein the eyepiece optical system comprises the first eyepiece. Reflects the light flux from the image,
It has at least a curved reflecting surface so as to be guided to the observer's eyeball side, and the reflecting surface is configured to have a function of transmitting a light beam from the second image transmitted through the see-through optical element; The optical element is more second than the reflection surface.
On the image side, arranged at an interval from the reflection surface, when the light flux from the second image passes through the see-through optical element and the eyepiece optical system, the light flux from the see-through optical element and the eyepiece optical system The combined optical power P is approximately 0
And an angle magnification β is substantially equal to 1. 2. A reflecting surface of the eyepiece optical system is configured to have a rotationally asymmetric curved surface shape that corrects decentering aberration, and a light flux from the second image is used for the see-through optical element and the eyepiece optical system. The see-through optical system is configured to cancel out the optical power and the angular magnification generated in the eyepiece optical system so that the combined optical power and angular magnification given when transmitting through the lens satisfy the following conditions. The observation optical system according to claim 1, wherein: -0.002 <Px <0.002 (3) -0.002 <Py <0.002 (4) 0.97 <βx <1.03 (5) 0.95 <Βy <1.05 (6) where the eccentric direction of the entire optical system is the Y-axis direction, a plane parallel to the axial principal ray is a YZ plane, and a direction orthogonal to the YZ plane. Is the X direction, the power of the whole system in the X direction is Px,
The power in the Y direction is Py, the angular magnification of the whole system in the X direction is βx,
The angular magnification of the entire system in the Y direction is βx. 3. The reflecting surface of the eyepiece optical system is formed in a rotationally asymmetric curved surface shape for correcting eccentric aberration, and the curved surface shape has only one anamorphic surface or a symmetric surface. 3. The observation optical system according to claim 1, wherein the observation optical system is configured by a symmetric free-form surface.