JPH09171151A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device capable of clearly observing the image with a wide view angle and being very small in size and light in weight. SOLUTION: This image display device is composed of an image display element 8 and an eyepiece optical system 9 for projecting the image and introducing it to an observer's eye. The eyepiece optical system 9 has four optical surfaces 12, 6, 5, 11 and is composed, in order of the path of a light ray according to reversely tracing the ray from the observer to the image display element 8, of a first transparent surface 11 close to the observer, a second translucent surface 5 having a definite curvature inclined to the visual axis of observer 2, a third reflection surface 6 opposite to the second surface 5 and a fourth transparent surface 12 close to the image display element 8. A space formed with the first surface 11, the third surface 6 and the fourth surface 12 is filled with a medium having a refractive index larger than 1.

Description

Detailed Description of the Invention

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image display device, and more particularly to a head or face-mounted image display device capable of being held on the head or face of an observer.

[0002]

2. Description of the Related Art In recent years, a helmet-type or goggle-type head- or face-mounted image display device has been developed for the purpose of enjoying a large-screen image for virtual reality or personally. This type of image display device needs to be mounted on the head for observation. Therefore, in order to minimize the physical burden on the observer, it is important to be small and lightweight. On the other hand, the larger the viewing angle of view, the larger the screen to be observed, and the observer can be given a strong sense of presence and immersion. Therefore,
It is an important condition of the image display device that the presented view angle is wide.

As a conventional well-known image display device for realizing a wide angle of view, as shown in cross-sections of FIGS. 31 and 32, JP-A-3-191389 and US Pat.
There is a 69,476 issue. In the case of FIG. 31, the light of the electronic image of the image display element passes through the half mirror, is magnified and reflected by the magnifying glass, and is reflected again by the half mirror.
The virtual image of the image of the image display element is enlarged and projected to the observer by entering the observer's eyeball.

In the case of FIG. 32, the space formed by the magnifying glass, the incident surface of the electronic image, the transmission surface on the observer pupil side and the surface on the opposite side is formed as a prism. The observation is performed by the same ray path as in FIG. 31, and the external light can be observed by passing through the half mirror and entering the observer's eyeball.

[0005]

In the optical system of the conventional image display apparatus as described above, when an attempt is made to widen the observation angle of view, the optical system becomes large or the distance between the optical system and the observer's eyeball. Tends to be shorter. FIG. 28 shows a process in which a ray emitted from the observer's pupil is reflected by a half mirror and reaches a concave mirror by the backward ray tracing from the pupil to the image display element. The following description will also be made by back ray tracing.

In FIG. 28, 1 is the observer's pupil position, 2 is the observer's visual axis, 3 is the optical axis of the image display element, 4 is the eyepiece optical system, 5 is a half mirror, 6 is a magnifying glass, and 8 is an image display. The angle between the element, the half mirror 5 and the optical axis 3 of the image display element is γ ₁ , the distance from the observer pupil 1 to the optical axis 3 of the image display element is g, and the observer's visual axis 2 and the half mirror 5 are The distance from the intersection P to the magnifying glass 6 is h.

The angle α ₁ formed by the light reflected by the half mirror 5 and the optical axis 3 when entering the eye at the angle of view θ is represented by α ₁ = π / 2-2γ ₁ + θ. Since γ ₁ is practically in the range of about 30 ° to 50 ° and is preset, α ₁ is considered to depend only on θ. If the intersection of the ray and the half mirror is Q ₁ , the distance s from Q ₁ to the optical axis 3
_{1, s 1 = g × tanθ /} {tanθ + tan (90-γ 1)} is (1). Here, since g and γ ₁ are setting conditions, they are considered to be constants. Fig. 2 shows a graph in which s ₁ is a function of θ.
9 shows. As is clear from the graph of FIG. 29, s ₁ monotonically increases with respect to θ. Further, t ₁ the distance from point Q ₁ to observer's visual axis _{2, t 1 = s 1 · tan} (90-γ 1) = g × tanθ × tan (90-γ 1) / {tanθ + tan (90 −γ ₁ )} is represented by (2). If tan (90-γ ₁ ) is a constant as described above, t ₁ has the same tendency as s ₁ .

The distance s _{2 in} the direction of the observer's visual axis 2 from the point Q ₁ to the reflection point of the magnifying glass 6 is s ₂ = (h + t ₁ ) tan α ₁ . Therefore, the distance w ₁ from the optical axis 3 of the image display element to the reflection point of the magnifying glass 6 is: w ₁ = s ₁ + s ₂ = s ₁ + (h + t ₁ ) tan α ₁ = s ₁ + {h + s ₁ · tan ( _{90-γ 1)} tanα 1} = g × tanθ / {tanθ + tan (90-γ 1)} + [h + g × tanθ × tan (90-γ 1) ÷ {tanθ + tan (90-γ 1)}] tanα 1 ... (3).

Here, γ _{1 is set} to 45 degrees for simplicity. α ₁ = θ, and w ₁ = s ₁ + (h + s ₁ ) tan θ = g × tan θ / (tan θ + 1) + {h + g × tan θ / (tan θ + 1)} tan θ (4). A graph in which w ₁ is a function of θ is shown in FIG.
It is clear from the graph of FIG. 30 that w ₁ monotonically increases with respect to θ.

Therefore, according to this structure, the larger the angle of view, the size of the magnifying glass 6 becomes dramatically larger, and accordingly, the entire optical system becomes larger. Since these image display devices are devices to be mounted on the observer's head, the larger the optical system, the larger the entire device and the weight, and the physical burden on the observer increases. It will be.

Further, if the distance between the optical system and the observer's eyeball becomes short, the observer cannot wear glasses to observe, and it becomes necessary for the observer to adjust the diopter of the optical system. Alternatively, a problem such as interference between the device and the observer's face occurs.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide a very small and lightweight image display device which allows clear observation in a wide angle of view. Is.

[0013]

An image display apparatus according to the present invention that achieves the above object has an image display element for displaying an image,
In an image display device comprising an eyepiece optical system that projects an image formed by the image display element and guides it to an observer's eyeball, the eyepiece optical system has at least four optical surfaces, and the image from the observer. A first surface that is a transmission surface that is close to the observer in the order in which the light rays pass according to the reverse ray tracing that reaches the display element, and a second surface that is a semi-transmission surface that has a finite curvature inclined with respect to the observer's visual axis. It is composed of a third surface which is a reflection surface facing the second surface and a fourth surface which is a transmission surface close to the image display element, and is formed by the first surface, the third surface and the fourth surface. The space is filled with a medium having a refractive index larger than 1.

In this case, the second surface is preferably a semi-transmissive surface with a concave surface facing the observer. Further, it is desirable that the first surface is a transmission surface having a positive power.

The operation of the image display device of the present invention will be described below. For convenience of design of the optical system, the description will be given by the backward ray tracing that traces a ray from the observer's pupil position toward the image display element.

In the present invention, the eyepiece optical system has at least four optical surfaces and is a transmission surface which is close to the observer in the order in which the light rays pass according to the backward ray tracing from the observer to the image display element. The first surface, the second surface which is a semi-transmissive surface having a finite curvature inclined with respect to the observer's visual axis, the third surface which is a reflective surface facing the second surface, and the transmissive surface which is close to the image display element. It is composed of a certain fourth surface, the first surface, the third surface,
Since the space formed by the fourth surface is filled with a medium having a refractive index larger than 1, the optical system does not become large and the distance between the optical system and the observer's eyeball is large even if the observation angle is wide. The present invention succeeds in providing an image display device that is not shortened.

In FIG. 26, in the image display device of the present invention, the ray from the observer's pupil is reflected by the half mirror and reaches the concave mirror by the backward ray tracing from the pupil to the image display element. In FIG. 26, 1 is the observer's pupil position, 2 is the observer's visual axis, 3 is the optical axis of the image display element, 9 is the eyepiece optical system, 8 is the image display element, 5 is a half mirror, 6 is a magnifying glass, and half. The angle formed by the mirror 5 and the optical axis 3 of the image display element is γ ₂ , the distance from the observer pupil 1 to the optical axis 3 of the image display element is g, and the intersection point P between the observer visual axis 2 and the half mirror 5 is P.
The distance from to the magnifying glass 6 is h.

Similar to FIG. 28, the case where the light enters the eye at the angle of view θ is shown, and the conditions of the optical system other than the half mirror 5 are the same. In addition, the half mirror and the light rays when the half mirror 5 is a plane are shown by dotted lines. Position of reflection point Q ₂ of the half mirror 5 is moved to the observer's pupil 1 side from Q _1.

The inclination of the tangent line on the spherical surface differs depending on the position. Assuming that the spherical surface is y ² + x ² = r ² (5), the tangent slope k is obtained by differentiating equation (5) by x.
^{Next, k = -x / (r 2} -x 2) represented by ^1/2 (6). This change in k in the range of x from 0 to 1 is shown in FIG. For example, γ ₁ in FIG. 26 is 45 °
In the case of, the point P on the axis is k = −1, and from there, it approaches x = 0 in the graph in the direction of Q ₂ . That is, the absolute value of the slope k of the tangent line 10 becomes small.

Therefore, the angle γ formed by the tangent line 10 and the optical axis 3
₂ increases, and the reflection angle β ₂ of the second surface increases accordingly, and the angle α ₂ formed by the light beam reflected by the half mirror 5 and the optical axis 3 decreases. Therefore, s ₃ shown in FIG.
Since the distance w ₂ between the optical axis 3 and the intersection of the magnifying glass 6 becomes short, the size of the magnifying glass 6 can be reduced, and the entire optical system can be made compact and lightweight.

Further, since the half mirror 5 has a curvature, the absolute value of k becomes smaller as the angle of view becomes larger, and accordingly β ₂ and γ ₂ become larger and w ₂ becomes smaller. The effect of reducing the area of the magnifying glass 6 is increased. That is, the effect of miniaturization by the half mirror 5 becomes great.

Further, according to the eyepiece optical system of the present invention, the reflection point of the light beam on the magnifying mirror 6 is located at a position farther from the observer due to the above-described effects, so that the observer's face and the eyepiece optical system are It becomes easy to secure the distance between the systems.

Further, by filling the space formed by the first surface, the third surface and the fourth surface with a medium having a refractive index larger than 1, the ray from the pupil is refracted on the first surface, so that it is off-axis. It is possible to obtain the effect of suppressing the heights of the chief ray and the dependent rays of the ray incident on the second surface to be low. Since the height of the chief ray is low, the second surface does not become large, and the eyepiece optical system can be downsized. Also, because the height of the dependent rays is low,
It is possible to suppress coma aberration, especially high-order coma aberration, which occurs on the second surface having a curvature.

Further, it is effective for obtaining the above-mentioned effect that the second surface is a semi-transmissive surface having a concave surface facing the observer.

Further, the off-axis ray strongly reduces its ray height only when the first surface is a transmitting surface having a positive power. It also has the effect of suppressing the heights of the dependent rays of the ray bundle at all angles of view. Therefore, the off-axis ray height incident on the second surface can be suppressed to a lower value, and the eyepiece optical system can be made small. Further, since the dependent rays on the second surface are narrowed, it has an effect of strongly suppressing the occurrence of coma aberration including aberration due to decentering.

Further, the third surface is a reflecting surface having a concave surface facing the second surface, so that a reflecting surface having a main positive power is arranged at a substantially intermediate position between the pupil and the object in the optical path. Therefore, the distance from the pupil to the first surface and the distance from the image display element to the fourth surface can be secured. Therefore, avoiding interference between the device and the observer, it becomes easy to adjust the position of the image display element,
The structure allows the diopter adjustment during assembly and mounting.

The eyepiece optical system has at least two components.
It is easy to make the power of the optical system asymmetrical on both sides of the optical axis by constructing the prism with two optical surfaces having power and inclined or decentered with respect to the observer's visual axis. On the other hand, it is effective when a coma aberration that is asymmetrically generated between the image on the image display element side and the image on the opposite side is corrected and a clearer and wider angle of view is secured.

Now, the smaller the image display device having a wider angle of view, the larger the inclination angle of the second surface, which is the first reflecting surface, and the more high-order coma aberrations occur. Further, astigmatism generated by the inclination of the surface also increases, so that the space formed by the first surface, the second surface, and the third surface has a refractive index of 1
It may be difficult to sufficiently correct these aberrations only by being filled with a larger medium.

Therefore, the refractive index of the medium which fills the space formed by the first surface, the second surface and the third surface is different from the refractive index of the medium which fills the space formed by the second surface and the fourth surface. By doing so, it becomes possible to more effectively correct the aberration generated in the eyepiece optical system.

Since the internal reflection of the second surface and the subsequent third surface is a reflecting surface, chromatic aberration does not occur on those surfaces. Further, since the chief ray on the fourth surface close to the image display element is substantially parallel to the optical axis, chromatic aberration is less likely to occur. Therefore, the chromatic aberration of the eyepiece optical system is dominated by the occurrence of chromatic aberration on the first surface which is the refracting surface. Further, in an optical system having a wide angle of view as in the present invention, lateral chromatic aberration is more prominent than axial chromatic aberration. In other words, it is important to correct the chromatic aberration of the medium generated on the first surface, which makes it possible to display a clearer and higher-resolution image. Therefore, as a configuration of the eyepiece optical system, it is possible to arrange optical elements having different media between the observer's eyeball and the image display element, and correct the chromatic aberration of magnification due to the difference in Abbe number of those media. .

It is effective for aberration correction that at least one of the first surface, the second surface, the third surface and the fourth surface is a decentered aspherical surface. As will be described later, the observer's visual axis is positive in the direction from the origin to the eyepiece optical system, the Z axis is orthogonal to the observer's visual axis, and is positive in the vertical direction from the bottom to the top when viewed from the observer's eyeball. If defined as the Y axis, which is orthogonal to the visual axis of the observer and is positive from right to left in the left-right direction when viewed from the observer's eye, at least one surface should be an eccentric aspherical surface as described above. Is an important condition for correcting coma aberration, particularly high-order coma aberration and coma flare, which occur on the second surface eccentric or inclined in the Y direction.

As in the present invention, in an image display apparatus using an eyepiece optical system of a type having a reflecting surface eccentrically or tilted in front of the observer's eyeball, the light rays incident on the reflecting surface are axially aligned. Since it is oblique, complicated coma aberration occurs. This complicated coma aberration increases as the inclination angle of the reflection surface increases. However, in order to realize a small-sized image display device having a wide angle of view, the image display element and the optical path interfere unless the eccentricity amount or the tilt angle is increased to some extent. Therefore, the smaller the image display device having a wide angle of view, the larger the inclination angle of the reflecting surface becomes, and an important problem is how to correct the occurrence of high-order coma aberration.

In order to correct such complicated coma aberration, at least one of the surfaces forming the eyepiece optical system is made an eccentric aspherical surface so that the power of the optical system is asymmetric with respect to the visual axis. Since the configuration can be adopted and the effect of the aspherical surface can be utilized off-axis, it becomes possible to effectively correct coma aberration including on-axis.

It is effective for aberration correction that at least one of the first surface, the second surface, the third surface and the fourth surface is an anamorphic surface. That is, it means that the radius of curvature in the YZ plane is different from the radius of curvature in the XZ plane orthogonal to this plane.

This condition is a condition for correcting an aberration caused by the eccentricity or inclination of the second surface with respect to the visual axis. In general, when the spherical surface is decentered, the light ray incident on the surface has different curvatures with respect to the light ray in the incident surface and in the surface orthogonal to the incident surface. Therefore, in the eyepiece optical system in which the reflecting surface is arranged in front of the observer's eyeball in a decentered or inclined manner with respect to the visual axis as in the present invention, the observation image on the visual axis, which is the center of the observation image, is not Point aberration occurs. In order to correct the astigmatism on this axis, the first surface, the second
By correcting the radius of curvature of at least one of the surface, the third surface, and the fourth surface in the plane of incidence and the plane orthogonal to this plane, astigmatism including the axis can be corrected. It is possible to provide a clear observation image.

It is desirable that any one of the first surface and the third surface of the eyepiece optical system is tilted or decentered with respect to the visual axis. By tilting or decentering any one of the first surface and the third surface, correction of coma aberration that occurs asymmetrically between the image on the image display element side and the image on the opposite side with respect to the visual axis, and the image is corrected. The surface on which the display element is arranged can be arranged substantially perpendicular to the optical axis after being reflected by the second surface. This is effective when an image display device such as a liquid crystal display device having poor viewing angle characteristics is used.

If at least one of the first surface, the second surface, the third surface and the fourth surface is a free-form surface, the above-mentioned effect of the aspherical surface or the anamorphic surface can be satisfied. Therefore, it is possible to effectively correct the aberration generated in the eyepiece optical system.

Here, the free curved surface is a curved surface expressed by the following equation (7). Here, x, y, and z represent orthogonal coordinates, C _nm is an arbitrary coefficient, and k and k ′ are also arbitrary.

When the angle between the normal to the second surface of the eyepiece optical system and the observer's visual axis (axial chief ray) is u, then 35 ° <u <60 ° (8) Is desirable.

This is a condition for disposing the eyepiece optical system and the image display element of the image display device of the present invention at appropriate positions. When the value exceeds the upper limit of 60 ° in the equation (8) and becomes large,
The coma generated on the second surface becomes so large that it cannot be corrected by the other surfaces. Further, the reflection points on the second surface and the third surface are too far apart, and the eyepiece optical system becomes very large. When the value becomes smaller than the lower limit of 35 °, the reflection angle on the second surface becomes small, and the light ray reflected by the second surface returns to the face direction.

When the curvature at the vertex of the second surface of the eyepiece optical system is C _HM , -0.03 <C _HM <-0.002 (mm ^-1 ) (9) is satisfied. It is desirable to do. The curvature C _HM of the second surface is (9)
When the ^value exceeds the upper limit of -0.002 mm ^{-1 in the} formula,
The effect of lowering the ray height of the marginal ray due to the curved second surface cannot be sufficiently obtained. When the ^value is smaller than the lower limit of −0.03 mm ⁻¹ , the power on the second surface becomes too strong, so that aberrations, especially coma, occur to the extent that they cannot be corrected on other surfaces.

Further, it is effective that the display surface of the image display element is arranged so as to be inclined with respect to the visual axis. When the refracting surface or the reflecting surface that constitutes the eyepiece optical system is decentered or inclined, the ray from the pupil has a different refraction angle or reflection angle at the refraction surface or the reflection surface depending on the image height, and the image surface is relative to the visual axis. May tilt. In that case, it is possible to correct the tilt of the image plane by disposing the image display element surface so as to be tilted with respect to the visual axis.

In the above image display device, by providing a means for positioning the image display element and the eyepiece optical system with respect to the observer's head, the observer can observe a stable image.

Further, by providing means for positioning the image display element and the eyepiece optical system with respect to the observer's head so that they can be mounted on the observer's head, the observer can freely observe the observing posture and the observing direction. The image can be observed with.

Further, by having the supporting means for supporting at least two sets of such image display devices at a constant interval, the observer can easily observe with both the left and right eyes. Further, it is possible to enjoy a stereoscopic image by displaying images with parallax on the image display surfaces of the left and right image display devices and observing them with both eyes.

[0046]

Embodiments 1 to 6 of an image display device of the present invention will be described below with reference to the drawings. The constituent parameters of each example will be described later, but in the following description, the surface number is shown as the surface number of the backward tracking from the observer's pupil position 1 to the eyepiece optical system 9. As shown in FIG. 1, the coordinates are taken from the iris position 1 of the observer as the origin, and the observer's visual axis 2 is the Z-axis with the direction from the origin toward the eyepiece optical system 9 being positive. A Y-axis that is orthogonal to the axis 2 and that is positive from the bottom to the top in the vertical direction when viewed from the observer's eye, and a axis that is orthogonal to the observer's visual axis 2 and that is positive from the right to the left in the left-right direction when viewed from the observer's eye. Define as an axis. That is, the inside of the plane of FIG. 1 described later is the YZ plane, and the plane perpendicular to the plane is the XZ plane. It is assumed that the optical axis is bent in the YZ plane of the drawing.

In the constituent parameters to be described later, regarding the surface on which the eccentricity amounts Y and Z and the tilt angle θ are described, the Y of the surface apex from one surface (pupil position 1) which is the reference surface. It means the amount of eccentricity in the axial direction, the Z-axis direction, and the angle of inclination of the central axis of the surface from the Z-axis, and in this case, θ means counterclockwise. It should be noted that the distance between the surfaces has no meaning.

In each surface, an aspherical shape which is a rotationally asymmetrical shape has coordinates R _y and R _{x which} are paraxial curvature radii in the YZ plane (paper surface) and X- Paraxial radii of curvature in the Z plane, K _x and K _y are the X-Z plane and Y-, respectively.
The conic coefficients AR and BR in the Z plane are the fourth-order and sixth-order aspherical coefficients rotationally symmetric with respect to the Z axis, respectively, and AP and BP are the fourth-order and sixth-order non-spherical coefficients rotationally asymmetric with respect to the Z axis, respectively. Assuming a spherical coefficient, the aspherical expression is as shown below.

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 + B
R [(1-BP) X 2 + (1 + BP) Y 2] 3 The refractive index of the medium between the surfaces is expressed by the refractive index of the d-line. The unit of the length is mm.

1 to 6 are sectional views of the monocular image display devices of Examples 1 to 6, respectively. In each cross-sectional view, 1 is the pupil position of the observer, 2 is the observer's visual axis,
Reference numeral 9 is an eyepiece optical system, 11 is a first surface of the eyepiece optical system 9, 5 is a half mirror which is the second surface of the eyepiece optical system 9, 6 is a magnifying glass (concave mirror) which is the third surface of the eyepiece optical system 9, Reference numeral 12 is a fourth surface of the eyepiece optical system 9, and 8 is an image display element.

The actual ray path in these examples is that the ray bundle emitted from the image display element 8 is the eyepiece optical system 9.
Is refracted by the fourth surface 12 of the optical system and enters the eyepiece optical system 9, passes through the half mirror 5, is reflected by the magnifying glass 6 and returns to the half mirror 5, and this time is reflected by the half mirror 5 and is made by the eyepiece optical system 9. The light is incident on the first surface 11 and is refracted, and is projected into the eyeball of the observer as the exit pupil 1 using the iris position of the observer's pupil or the center of rotation of the eyeball.

The values of the angle of view and the like in each example are defined by the horizontal angle of view of 40 °, the vertical angle of view of 30.6 °, the pupil diameter of 4 mm, the normal line of the half mirror 5 and the observer's visual axis 2 in the first embodiment. Angle 37.42
°, curvature at the top of half mirror -0.0056mm
It is ^-1 .

Horizontal angle of view 30 ° and vertical angle of view 2 in Example 2
It is 2.8 °, the pupil diameter is 8 mm, the angle between the normal line of the half mirror 5 and the observer's visual axis 2 is 39.9 °, and the curvature at the top of the half mirror 5 is −0.0046 mm ⁻¹ .

Horizontal angle of view 45 ° and vertical angle of view 3 in Example 3
The angle is 4.6 °, the pupil diameter is 4 mm, the angle between the normal line of the half mirror 5 and the observer's visual axis 2 is 43.45 °, and the curvature at the top of the half mirror 5 is −0.01 mm ⁻¹ .

Horizontal angle of view 45 ° and vertical angle of view 3 in Example 4
The angle is 4.6 °, the pupil diameter is 4 mm, the angle formed by the normal line of the half mirror 5 and the observer's visual axis 2 is 38.59 °, and the curvature at the top of the half mirror 5 is −0.005 mm ⁻¹ .

Horizontal angle of view 45 ° and vertical angle of view 3 in Example 5
The angle is 4.6 °, the pupil diameter is 4 mm, the angle formed by the normal line of the half mirror 5 and the observer's visual axis 2 is 41.8 °, and the curvature at the top of the half mirror 5 is −0.0055 mm ⁻¹ .

Horizontal angle of view 40 ° and vertical angle of view 3 in Example 6
The angle is 0.6 °, the pupil diameter is 8 mm, the angle between the normal line of the half mirror 5 and the observer's visual axis 2 is 42.39 °, and the curvature at the apex of the half mirror 5 is −0.0038 mm ⁻¹ . The values of the constituent parameters of Examples 1 to 6 are shown below.

Example 1 Surface number Curvature radius Spacing Refractive index Abbe number (Eccentricity) (Tilt angle) 1 ∞ (pupil) 2 ∞ 1.5254 56.25 Y 0.0000 θ -3.72 ° Z 20.355 3 R _y -179.211 1.5254 56.25 R _x- 165.411 Y -2.194 θ 37.42 ° K _y 0 Z 35.355 K _x 0 AR 0.127284 × 10 ^-5 BR -0.565396 × 10 ^-13 AP -0.107951 BP -0.119600 × 10 ² 4 R _y 180.917 1.5254 56.25 R _x 99.112 Y -12.807 θ _{84.69 ° K y 0 Z 48.355 K} x 0 AR 0.108134 × 10 -5 BR 0.211006 × 10 -10 AP -0.199934 BP 0.108930 × 10 1 5 R y -30.858 Y 11.666 θ 107.71 ° R x -37.728 Z 10.085 K y -0.648366 K _x -4.488275 AR 0.283824 × 10 ^-4 BR -0.406175 × 10 ^-7 AP -0.117155 × 10 ¹ BP -0.974334 6 (image display device) Y 15.451 θ 88.11 ° Z 33.857.

Example 2 Surface number Curvature radius Spacing Refractive index Abbe number (Eccentricity) (Tilt angle) 1 ∞ (pupil) 2 ∞ 1.5254 56.25 Y 0.0000 θ -9.32 ° Z 20.000 3 R _y -218.075 1.5254 56.25 R _x- 153.445 Y 4.969 θ 39.90 ° K _y -3.368535 Z 31.862 K _x -10.000000 AR 0.571943 × 10 ^-6 BR -0.917414 × 10 ^-12 AP -0.368789 BP -0.587966 × 10 ¹ 4 R _y 224.186 1.5254 56.25 R _x 162.490 Y -13.161 _{θ 83.54 ° K y 0 Z 41.138} K x 0 AR 0.948197 × 10 -6 BR 0.156382 × 10 -12 AP -0.122671 BP 0.753978 × 10 1 5 R y -1413.225 Y 12.660 θ 68.09 ° R x -87.184 Z 25.000 K y - 8.000000 K _x 10.000000 AR 0.270191 × 10 ^-5 BR -0.776615 × 10 ^-9 AP -0.595865 BP 0.479127 6 (image display device) Y 19.617 θ 97.26 ° Z 28.387.

Example 3 Surface number Curvature radius Spacing Refractive index Abbe number (Eccentricity) (Inclination angle) 1 ∞ (Pupil) 2 R _y -173.329 1.5254 56.25 R _x 41.324 Y -3.353 θ -2.43 ° K _y 0 Z 20.147 K _x 0 AR -0.329652 × 10 ^-6 BR 0.523728 × 10 ^-11 AP 0.876156 × 10 ¹ BP -0.202358 × 10 ² 3 R _y -100.000 1.5254 56.25 R _x 952.298 Y -0.313 θ 43.45 ° K _y 0 Z 31.542 K _x 0 AR -0.789469 × 10 ^-10 BR 0.314882 × 10 ^-10 AP -0.126990 × 10 ³ BP 0.239103 × 10 ¹⁴ R _y 699.924 1.5254 56.25 R _x 60.372 Y -13.353 θ 79.33 ° K _y 0 Z 43.377 K _x 0 AR 0.472554 ^{× 10 -10 BR 0.423116 × 10 -12} AP 0.935918 × 10 2 BP 0.139150 × 10 2 5 R -11.757 Y 11.484 θ 89.25 ° R x -4.496 Z 24.253 K y -1.774022 K x -3.509119 AR 0.822394 × 10 -4 BR -0.179411 x 10 ^-6 AP -0.127684 x 10 ¹ BP -0.114684 x 10 ¹
6 (Image display element) Y 10.037 θ 73.55 ° Z 37.142.

Example 4 Surface number Curvature radius Spacing Refractive index Abbe number (Eccentricity) (Tilt angle) 1 ∞ (Pupil) 2 R _y -288.420 1.5254 56.25 R _x -613.123 Y 0.671 θ 0.03 ° K _y 0 Z 20.040 K _x 0 AR 0.115829 × 10 ^-4 BR 0.204909 × 10 ^-14 AP 0.203677 BP 0.171442 × 10 ³ 3 R _y -200.000 1.5254 56.25 R _x -261.675 Y -1.792 θ 38.59 ° K _y 0 Z 35.040 K _x 0 AR 0.163562 × 10 ^{-5 BR -0.301809 × 10 -15 AP -0.564787} × 10 -1 BP -0.123717 × 10 3 4 R y 102.370 1.5254 56.25 R x 68.331 Y -13.876 θ 87.47 ° K y 0 Z 48.040 K x 0 AR 0.992790 × 10 - ^{6 BR 0.605520 × 10 -12 AP -0.238580} BP 0.610124 × 10 1 5 R y -40.454 Y 6.671 θ 113.70 ° R x -38.017 Z 3.099 K y -0.232146 K x -5.408361 AR 0.921621 × 10 -4 BR -0.107135 × 10 ^-6 AP -0.108753 × 10 ¹ BP -0.957482 6 (image display device) Y 11.393 θ 81.18 ° Z 36.812.

Example 5 Surface Number Curvature Radius Spacing Refractive Index Abbe Number (Eccentricity) (Tilt Angle) 1 ∞ (Pupil) 2 ∞ 1.5254 56.25 Y -15.000 θ 0.00 ° Z 20.000 3 R _y -183.184 1.5254 56.25 R _x- 172.198 Y 18.348 θ 41.80 ° K _y 0 Z 21.000 K _x 0 AR 0.388012 × 10 ^-6 BR -0.933882 × 10 ^-10 AP -0.173951 × 10 ^-1 BP -0.223255 4 72.254 1.5254 56.25 Y -11.323 θ 73.43 ° Z 28.472 5 _{R y -92.917 Y 12.110 θ 79.60 °} R x -42.127 Z 20.000 K y 0 K x 0 AR 0.128407 × 10 -4 BR -0.307966 × 10 -10 AP -0.161439 BP 0.517646 × 10 1 6 ( image display device) Y 12.512 θ 86.16 ° Z 35.183.

Example 6 Surface number Curvature radius Spacing Refractive index Abbe number (Eccentricity) (Inclination angle) 1 ∞ (Pupil) 2 256.499 1.4870 70.40 Y 76.098 θ -9.60 ° Z 26.430 3 R _y -261.011 1.4870 70.40 R _x- 604.816 Y 30.709 θ 42.39 ° K _y -10.000000 Z 25.177 K _x 0 AR -0.100334 × 10 ^-8 BR -0.137823 × 10 ^-10 AP -0.679774 × 10 ¹ BP -0.312747 4 R _y 166.156 1.4870 70.40 R _x 106.217 Y -21.391 θ 72.57 ° K _y 0 Z 51.676 K _x 0 AR -0.171410 × 10 ^-9 BR 0.106042 × 10 ^-10 AP 0.286805 × 10 ² BP 0.948785 5 R _y -261.011 1.54787 47.40 R _x -604.816 Y 30.709 θ 42.39 ° K _y- 10.000000 Z 25.177 K _x 0 AR -0.100334 × 10 ^-8 BR -0.137823 × 10 ^-10 AP -0.679774 × 10 ¹ BP -0.312747 6 R _y 74.598 Y 8.126 θ 112.83 ° R _x 111.513 Z 81.238 K _y 0 K _x 0 AR ^{0.942722 × 10 -6 BR -0.412902 × 10} -11 AP 0.261913 × 10 1 BP 0.378035 × 10 1 7 ( image display device) Y 19.346 θ 71.17 ° Z 78.835.

Next, FIGS. 7 to 9 are transverse aberration diagrams of the first embodiment, and FIG. 10 is a transverse aberration diagram of the second to sixth embodiments.
-FIG. 12, FIG. 13-FIG. 15, FIG. 16-FIG. 18, FIG.
It is shown in FIGS. 21 and 22 to 24. In these lateral aberration diagrams, the numbers in parentheses are (horizontal angle of view, vertical angle of view)
Represents the lateral aberration at that angle of view.

The image display apparatus of the present invention has been described above based on the embodiments, but the present invention is not limited to these embodiments and various modifications can be made. To configure the image display device of the present invention as a head-mounted image display device (HMD) 21, as shown in a sectional view of FIG. 25 (a) and a perspective view of FIG. Attach it to the observer's head and use it. In the case of this usage example, the semi-transmissive mirror (half mirror) 5 on the second surface of the eyepiece optical system 9 is used.
A liquid crystal shutter 13 is provided in front of the image display device so that the external image can be observed selectively or by superimposing the image on the image display device 8.

The above-described image display device of the present invention can be configured as follows, for example. [1] In an image display device including an image display element that displays an image and an eyepiece optical system that projects an image formed by the image display element and guides it to an observer's eye, the eyepiece optical system has at least four surfaces. A first surface having an optical surface, which is a transmissive surface close to the observer in the order in which the light rays pass in accordance with the backward ray tracing from the observer to the image display element,
A second surface, which is a semi-transmissive surface having a finite curvature inclined with respect to the observer's visual axis, and a third surface, which is a reflecting surface facing the second surface,
It is composed of a fourth surface, which is a transmission surface close to the image display element, and the space formed by the first surface, the third surface, and the fourth surface is filled with a medium having a refractive index larger than 1. An image display device characterized by being.

[2] The image display device according to [1], wherein the second surface is a semi-transmissive surface having a concave surface facing an observer.

[3] The image display device according to the above [1], wherein the first surface is a transmissive surface having a positive power.

[4] The above-mentioned [1], wherein the third surface is a reflecting surface having a concave surface facing the second surface.
The image display device as described in the above.

[5] The image display according to the above [1], wherein at least two of the at least four surfaces have power and are inclined or eccentric with respect to the observer's visual axis. apparatus.

[6] The refractive index of the medium that fills the space formed by the first surface, the second surface, and the third surface, and the second refractive index of the medium.
The image display device according to the above [1], wherein the image display device has a refractive index different from that of a medium that fills the space formed by the surface and the fourth surface.

[7] The image display device according to [1], wherein at least one of the first surface, the second surface, the third surface and the fourth surface is an eccentric aspherical surface.

[8] The image display device according to the above [7], wherein at least one of the first surface, the second surface, the third surface and the fourth surface is an anamorphic surface.

[0074]

[9] The image display device according to [7], wherein at least one of the first surface, the second surface, the third surface, and the fourth surface is a free-form surface.

[10] When the angle formed by the normal line to the second surface and the observer's visual axis is u, then 35 ° <u <60 ° (8) is satisfied. 1] The image display device according to item 1).

[11] The curvature at the top of the second surface is C
_{When HM} , −0.03 <C _HM <−0.002 (mm ⁻¹ ) ... (9) is satisfied, The image display device according to the above [1].

[12] The image display according to any one of the above [1] to [11], wherein the display surface of the image display element is arranged so as to be inclined with respect to the observer's visual axis. apparatus.

[13] The image according to any one of [1] to [12], which has a positioning means for positioning the image display element and the eyepiece optical system with respect to the observer's head. Display device.

[14] The above [1] to [1] characterized in that the image display device and the eyepiece optical system have a supporting means for supporting the head of the observer and can be mounted on the head of the observer. 12] The image display device according to any one of [12].

[15] The image display device according to any one of the above [1] to [14], which has a supporting means for supporting at least two sets of the image display device at a constant interval.

[0081]

As is apparent from the above description, according to the image display device of the present invention, it is possible to provide an image display device which is very small and lightweight with a wide observation angle of view.

[Brief description of the drawings]

FIG. 1 is a sectional view of an image display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an image display device according to a second embodiment of the present invention.

FIG. 3 is a sectional view of an image display device according to a third embodiment of the present invention.

FIG. 4 is a sectional view of an image display device according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of an image display device according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view of an image display device according to a sixth embodiment of the present invention.

FIG. 7 is a part of a lateral aberration diagram of Example 1 of the present invention.

FIG. 8 is a part of the remaining lateral aberration diagram of Example 1 of the present invention.

FIG. 9 is the remaining portion of the lateral aberration diagram for Example 1 of the present invention.

FIG. 10 is a part of a transverse aberration diagram for Example 2 of the present invention.

FIG. 11 is a part of the remaining lateral aberration diagram of Example 2 of the present invention.

FIG. 12 is the remaining portion of the lateral aberration diagram for Example 2 of the present invention.

FIG. 13 is a part of a lateral aberration diagram of Example 3 of the present invention.

FIG. 14 is a remaining part of the lateral aberration diagram of Example 3 of the present invention.

FIG. 15 is the remaining portion of the lateral aberration diagram for Example 3 of the present invention.

FIG. 16 is a part of a lateral aberration diagram of Example 4 of the present invention.

FIG. 17 is the remaining part of the lateral aberration diagram of Example 4 of the present invention.

FIG. 18 is the remaining portion of the lateral aberration diagram for Example 4 of the present invention.

FIG. 19 is a part of a transverse aberration diagram for Example 5 of the present invention.

FIG. 20 is a part of the remaining lateral aberration diagrams of Example 5 of the present invention.

FIG. 21 is the remaining portion of the lateral aberration diagram for Example 5 of the present invention.

FIG. 22 is a part of a lateral aberration diagram according to Example 6 of the present invention.

FIG. 23 is a part of the remaining lateral aberration diagram of Example 6 of the present invention.

FIG. 24 is the remaining portion of the lateral aberration diagram for Example 6 of the present invention.

FIG. 25 is a sectional view and a perspective view of a head-mounted image display device according to the present invention.

FIG. 26 is an explanatory diagram related to the eyepiece optical system of the image display device of the present invention.

FIG. 27 is a graph showing changes in the inclination of the tangent line of the half mirror of the eyepiece optical system according to the present invention.

FIG. 28 is an explanatory diagram of an eyepiece optical system of a conventional image display device.

FIG. 29 is a graph showing a change in the position of a reflection point on a half mirror of a conventional eyepiece optical system.

FIG. 30 is a graph showing changes in the positions of reflection points in the magnifying glass of the conventional eyepiece optical system.

FIG. 31 is a diagram showing an optical system of one conventional image display device.

FIG. 32 is a diagram showing an optical system of another conventional image display device.

[Explanation of symbols]

 1 ... Observer pupil position 2 ... Observer visual axis 3 ... Optical axis of image display element 5 ... Second surface of eyepiece optical system (half mirror) 6 ... Third surface of eyepiece optical system (magnifying glass) 8 ... Image display Element 9 ... Eyepiece optical system 10 ... Half mirror tangent line 11 ... Eyepiece optical system first surface 12 ... Eyepiece optical system fourth surface 13 ... Liquid crystal shutter 20 ... Headband 21 ... Head mounted image display device (HMD)

Claims (3)

[Claims] 1. An image display device comprising an image display element for displaying an image and an eyepiece optical system for projecting the image formed by the image display element to guide it to an observer's eye, wherein the eyepiece optical system is at least 4 The first surface, which is a transmission surface close to the observer, is inclined with respect to the observer's visual axis in the order in which the light rays pass according to the backward ray tracing from the observer to the image display element The second surface is a semi-transmissive surface having a finite curvature, the third surface is a reflective surface facing the second surface, and the fourth surface is a transmissive surface close to the image display element. An image display device, wherein the space formed by the surface, the third surface, and the fourth surface is filled with a medium having a refractive index larger than 1. 2. The image display device according to claim 1, wherein the second surface is a semi-transmissive surface having a concave surface facing an observer. 3. The image display device according to claim 1, wherein the first surface is a transmissive surface having a positive power.