WO2012132959A1

WO2012132959A1 - Visual display device

Info

Publication number: WO2012132959A1
Application number: PCT/JP2012/056846
Authority: WO
Inventors: 孝吉研野
Original assignee: オリンパス株式会社
Priority date: 2011-03-25
Filing date: 2012-03-16
Publication date: 2012-10-04

Abstract

A visual display device comprises: one image display screen which displays an observed image; and an ocular optical assembly which forms two eye points for directing the observed image to both eyes of an observer. The ocular optical assembly further comprises one reflecting surface which has a positive refraction and which is positioned facing the two eye points. In backlight tracking order from the two eye points to the image display screen, a light beam which exits the two eye points is reflected by the reflecting surface which is positioned facing the two eye points, the light beam after reflection by the reflecting surface enters the image display screen, and formula (1), following, is satisfied: -1.0 ≤ S ≤ 1.0 (1) Where S[m^-1] is the difference between a virtual image location by visibility and a virtual image location by congestion within an observation angle of field.

Description

Visual display device

The present invention relates to a visual display device capable of natural observation with both eyes.

Conventionally, there are technologies as described in Patent Documents 1 to 8 as visual display devices.

Japanese Patent No. 3155335 Japanese Patent No. 3155337 Japanese Patent No. 3155341 Japanese Patent No. 3994896 JP-A-1-290386 Japanese Patent Laid-Open No. 11-38505 JP 2010-44177 A JP 2011-85790 A Japanese Patent No. 4816605 JP 2006-103589 A JP 2003-237411 A

Patent Documents 1 to 4 are optical systems close to the present invention, but use two sets of display units each composed of a display element and an eyepiece optical system for observation with one eye. In Patent Documents 5 to 6, an intermediate image formed by a projector or the like is enlarged with a large concave mirror and observed with both eyes. Since the focal length of the concave mirror is longer than that of the eye, the occurrence of aberrations is reduced, and diopter and The problem of congestion deviation did not occur. Furthermore, Patent Document 7 has a relatively short focal length, which causes problems of diopter and convergence of virtual images. Patent Document 8 discloses a method of performing stereoscopic viewing with a lenticular lens and a convex lens. Patent Documents 9 to 10 disclose an optical system of a head-mounted display using a holographic combiner, and an optical system of a concave mirror in which a reflecting surface is formed on a windshield in order to reduce production costs. Yes.

In one aspect of the present invention, the visual display device includes: one image display surface for displaying an observation image; and an eyepiece optical system that forms two eye points for guiding the observation image to both eyes of the observer. The eyepiece optical system has one reflecting surface having a positive refractive index disposed so as to face the two eye points, and performs reverse ray tracing from the two eye points to the image display surface. In order, the light beam emitted from the two eye points is reflected by the reflecting surface disposed so as to face the two eye points, and the light beam reflected by the reflecting surface is incident on the image display surface. The following conditional expression (1) is satisfied.
-1.0 ≤ S ≤ 1.0 (1)
However, S [m ⁻¹ ] is the difference between the virtual image position due to diopter and the virtual image position due to convergence within the observation angle of view.

In one embodiment of the present invention, the central principal ray emitted from the two eye points from the center of the coordinate system is set to the center of the coordinate system of the center position of the central principal ray emitted from the two eye points. Is the positive direction of the Z-axis, the direction going to the point intersecting the object plane, the line connecting the emission positions of the central principal rays that pass through the center of the coordinate system and exit from the two eye points, and the positive direction of the Z-axis In a coordinate system having a positive direction of the Y axis and a positive direction of the X axis forming a right-handed system together with the positive direction of the Z axis and the positive direction of the Y axis. The condition (2) is satisfied.
−300 <Fy <−100 (2)
However,
Fy is the focal length of the reflecting surface in the Y-axis direction.

In one embodiment of the present invention, the following conditional expression (3) is satisfied.
0.9 <Fx / Fy <1.1 (3)
However,
Fx is the focal length of the reflecting surface in the X-axis direction,
Fy is the focal length of the reflecting surface in the Y-axis direction,
It is.

In one embodiment of the present invention, the reflecting surface has a first curvature in the X-axis direction corresponding to a positive first value on the Y-axis, on the Y-axis having the same absolute value as the first value. Is smaller than the second curvature in the X-axis direction corresponding to the negative second value.

In one embodiment of the present invention, the following conditional expression (4) is satisfied.
-0.5 ≤ S ≤ 0.5 (4)
However, S [m ⁻¹ ] is the difference between the virtual image position due to diopter and the virtual image position due to convergence within the observation angle of view.

In one embodiment of the present invention, the reflecting surface is a free-form surface.

Also, an aspect of the present invention is characterized in that an optical element having a refractive action is disposed closer to the image display surface than the reflection surface, and the transmission surface of the optical element is configured as a free-form surface.

In one embodiment of the present invention, the optical element has a first curvature in the X-axis direction corresponding to a positive first value on the Y-axis on the Y-axis having the same absolute value as the first value. The shape is smaller than the second curvature in the X-axis direction corresponding to the negative second value.

Further, according to an aspect of the present invention, the image display apparatus includes a lenticular lens that distributes the image displayed on the image display surface to the left and right eyes.

In one embodiment of the present invention, at least one of the reflecting surfaces is a semi-transmissive surface.

In one embodiment of the present invention, the transflective surface has a wavelength dependency.

It is the figure which looked at the cross section containing the optical path of two center chief rays of the visual display apparatus of Example 1 from the top. It is the figure which expanded a part of visual display apparatus of Example 1. FIG. It is the figure which looked at the positive direction of the X-axis from the YZ cross section. It is a graph which shows the curvature of the horizontal direction of a reflective surface. FIG. 4 is a diagram showing lateral aberration charts of Example 1. FIG. 4 is a diagram showing lateral aberration charts of Example 1. FIG. 3 is a diagram showing a state in which a lenticular lens 45 is disposed between the image display surface 5 and the optical path of the optical element 4. It is an enlarged view near the lenticular lens 45. It is the figure which looked at the cross section containing the optical path of two center chief rays of the visual display apparatus of Example 2 from the top. It is the figure which expanded a part of visual display apparatus of Example 2. FIG. It is the figure which looked at the positive direction of the X-axis from the YZ cross section. It is a graph which shows the curvature of the horizontal direction of a reflective surface. FIG. 6 is a diagram showing lateral aberration charts of Example 2. FIG. 6 is a diagram showing lateral aberration charts of Example 2. It is the figure which looked at the cross section containing the optical path of the two center principal rays of the visual display apparatus of Example 3 from the top. It is the figure which expanded a part of visual display apparatus of Example 3. FIG. It is the figure which looked at the positive direction of the X-axis from the YZ cross section. It is a graph which shows the curvature of the horizontal direction of a reflective surface. It is a graph which shows the curvature of the horizontal direction of a field lens. FIG. 6 is a diagram showing lateral aberration charts of Example 3. FIG. 6 is a diagram showing lateral aberration charts of Example 3. 6 is a graph showing a difference between a virtual image position due to diopter and a virtual image position due to convergence within the observation angle of view of Example 1, Example 2, and Example 3. FIG. 3 is a graph showing distortion of Example 1. 6 is a graph showing distortion in Example 2. 10 is a graph showing distortion of Example 3.

Hereinafter, the optical system will be described based on examples.

FIG. 1 is a top view of a cross section including the optical paths of two central principal rays of the visual display device 1 according to the first embodiment.

The visual display device 1 includes one image display surface 5 that displays an observation image, and an eyepiece optical system 2 that forms two eye points E for guiding the observation image to both eyes of an observer. The system 2 has one reflecting surface 4a having a positive refractive index disposed so as to face the two eye points E, and in order of back ray tracing from the two eye points E to the image display surface 2, A light beam emitted from one eye point E is reflected by the reflecting surface 4a arranged so as to face the two eye points E, and the light beam reflected by the reflecting surface 4a is incident on the image display surface 5, It is preferable that the conditional expression (1) is satisfied.
-1.0 ≤ S ≤ 1.0 (1)
However, S [m ⁻¹ ] is the difference between the virtual image position due to diopter and the virtual image position due to convergence within the observation angle of view.

Conventionally, a so-called head-mounted display: HMD (Head-Mounted-Display) is known as one that provides an observation image by arranging an eyepiece optical system and a display element for each eye. The head-mounted display is positioned with respect to the observer's head because the means for relatively positioning the two eyepiece optical systems and the display element and the diameter of the eye point (exit pupil) corresponding to both eyes are small. There is a need. Therefore, a complicated mechanism is required to give a sense of restraint to bring the device into contact with the observer's head and to maintain the positional relationship between the optical systems of both eyes.

Also, the transmission type magnifying glass system using a convex lens or a Fresnel lens has a problem that the whole becomes large.

On the other hand, if a decentered optical path using a reflecting mirror is taken, decentration aberrations occur, and there is a problem that the virtual image position due to diopter and the virtual image position due to convergence shift. For example, if the reflecting mirror is formed of a spherical surface, the angle of convergence of the image observed on the upper side of the observation angle of view (on the display element side of the visual axis) increases, and the image is observed in front. Even if the diopter (focus position of the virtual image) is 2m ahead set by the central angle of view, the convergence observed with both eyes will be closer to it, and if it is terrible, it will be observed as a double image There is a bug. This is because the display element and the left and right eyeballs of the observer are three-dimensionally eccentric.

Therefore, in the present embodiment, the convergence angle is made constant in the screen, the inclination of the virtual image plane is eliminated, and the difference between the diopter and the convergence is made ± 1 [m ⁻¹ ] or less.

By satisfying conditional expression (1), a virtual image can be observed in the distance with both eyes, and the diopter of the virtual image and the vergence when observed with both eyes are the same, the observation angle of view is wide, and the structure is compact and has a small structure. A simple visual display device can be provided.

If the upper limit of conditional expression (1) is exceeded, the virtual image plane will appear bent. If the lower limit of conditional expression (1) is not reached, the plane image will feel uncomfortable.

The midpoint of the emission position of the central principal ray emitted from the two eye points E is defined as the center O of the coordinate system, and the central principal ray Rc emitted from the center point O of the coordinate system is the object plane 3. The direction toward the intersecting point 3c is perpendicular to the positive direction of the Z axis, and is orthogonal to the line connecting the exit position Ec of the central principal ray Rc exiting from the two eye points E through the center O of the coordinate system and the positive direction of the Z axis. In the coordinate system having the positive direction of the Y-axis and the positive direction of the X-axis forming the right-handed orthogonal coordinate system together with the positive direction of the Z-axis and the positive direction of the Y-axis, the direction toward the image display surface 5 is as follows. It is preferable that the conditional expression (2) is satisfied.
−300 <Fy <−100 (2)
However,
Fy is the focal length of the reflecting surface 4a in the Y-axis direction.

If the upper limit of conditional expression (2) is exceeded, the reflecting surface 4a becomes small, but the torsion of rays incident on both eyes becomes large and the eccentricity is large, resulting in large decentration aberrations. Correction becomes difficult. If the lower limit of conditional expression (2) is not reached, the reflecting surface 4a becomes large, and it becomes difficult to realize a small device.

Moreover, it is preferable that the following conditional expression (3) is satisfied.
0.9 <Fx / Fy <1.1 (3)
However,
Fx is the focal length of the reflecting surface 4a in the X-axis direction,
Fy is the focal length of the reflecting surface 4a in the Y-axis direction,
It is.

Conditional expression (3) relates to astigmatism. Even if the upper limit of conditional expression (3) is exceeded or below the lower limit, astigmatism increases and it becomes difficult to observe a clear observation image.

In addition, the reflecting surface 4a has a first curvature in the X-axis direction corresponding to a positive first value on the Y-axis that is a negative second value on the Y-axis having the same absolute value as the first value. The shape is preferably smaller than the corresponding second curvature in the X-axis direction.

The light beam emitted from the image display surface 5 travels toward the reflection surface while spreading toward both the left and right eyes, but has an eccentric arrangement, so the optical path length to the reflection surface is different above and below the viewing angle. For this reason, the opening angles of the left and right optical axes after reflection on the reflecting surface, that is, convergence are also different. The diopter corresponding to the so-called focus position is adjusted so that the display surface is 2m ahead, but the convergence, that is, the angle formed by the left and right optical axes, does not have an intersection point 2m away, and is different at the top and bottom of the screen. Come on. In order to correct this, it is important to correct by increasing the curvature in the lateral (x) direction as going to the two-dimensional display element side.

Moreover, it is preferable that the following conditional expression (4) is satisfied.
-0.5 ≤ S ≤ 0.5 (4)
However, S [m ⁻¹ ] is the difference between the virtual image position due to diopter and the virtual image position due to convergence within the observation angle of view.

As with conditional expression (1), it becomes easier to see when the diopter and the convergence are more consistent.

Furthermore, it is preferable that the following conditional expression (5) is satisfied.
-0.1 ≤ S ≤ 0.1 (5)

Further, the reflecting surface 4a is preferably a free-form surface.

By appropriately giving the free-form surface x ² y term, the curvature in the X direction can be easily increased as it goes in the positive direction of the Y axis.

Further, it is preferable that a field lens 6 as an optical element having a refractive action is arranged near the image display surface 5 from the reflection surface 4a, and the transmission surface 6b of the field lens 6 is configured by a free-form surface.

By configuring the transmission surface 6b as a free-form surface and disposing the field lens 6 having a refractive action close to the image display surface 5, it becomes possible to correct bow-shaped image distortion.

Further, the field lens 6 has a negative second value on the Y-axis in which the first curvature in the X-axis direction corresponding to the positive first value on the Y-axis has the same absolute value as the first value. It is preferable that the shape be larger than the second curvature in the X-axis direction corresponding to.

By configuring the field lens 6 in this way, it becomes possible to successfully cancel the bow-shaped distortion and the trapezoidal distortion generated on the reflecting surface 4a with the field lens 6. Further, the field lens 6 has a first curvature in the X-axis direction corresponding to a positive first value on the Y-axis to a negative second value on the Y-axis having the same absolute value as the first value. More preferably, it is used simultaneously with the reflecting surface 4a having a shape smaller than the corresponding second curvature in the X-axis direction.

It is also preferable to have a lenticular lens that distributes the image displayed on the image display surface to the left and right eyes.

By having a lenticular lens, it is possible to observe a natural stereoscopic observation image by making each pixel correspond to the left and right eyes alternately.

Further, it is preferable that at least one of the reflective surfaces is a semi-transmissive surface. By making the reflecting surface into a concave mirror shape, it becomes possible to observe a distant virtual image in which convergence and diopter coincide with each other even at an angle of view of 30 °. Furthermore, a semi-transmissive concave mirror can be provided at low cost by forming a thin film having a semi-transmissive action on the concave mirror by vacuum deposition or the like.

Moreover, it is preferable that the transflective surface has wavelength dependency. An image can be displayed without darkening an external image by using a semi-transmission surface having a wavelength dependency.

The observed virtual image plane (object plane 3 on tracking) is assumed to be 2 m ahead, but this can be set arbitrarily.

Furthermore, when the reflecting mirror 4a is manufactured by plastic injection molding, it is preferably a surface mirror. By using a surface mirror, it is possible to avoid image degradation due to internal distortion that occurs during injection molding.

Furthermore, it is preferable that the field lens 6 has a high refractive index (MR-174, episulfide-based resin, refractive index 1.74, Abbe number 33) because aberrations are reduced.

Hereinafter, examples of the visual display device will be described. The configuration parameters of the optical system will be described later.

As shown in FIG. 1, the coordinate system is such that the midpoint of the emission position Ec of the central principal ray Rc emitted from the two eye points E is the center O of the coordinate system, and the two eye points E are defined from the center O of the coordinate system. The direction toward the point 3c where the emitted central principal ray Rc intersects the object plane 3 is the positive direction of the Z axis, and the exit position Ec of the central principal ray Rc emitted from the two eye points E through the center O of the coordinate system is connected. The right-handed orthogonal coordinate system is formed together with the positive direction of the Y-axis and the positive direction of the Z-axis and the positive direction of the Y-axis in the direction perpendicular to the elliptical line and the positive direction of the Z-axis and toward the image display surface 5. Has the positive direction of the axis.

FIG. 1 is a top view of a cross section including the optical path of the central principal ray of the visual display device 1 according to the first embodiment, FIG. 2 is an enlarged plan view of a part of the visual display device 1 according to the first embodiment, and FIG. It is the figure which looked at the positive direction of the X-axis from the YZ cross section. FIG. 4 is a graph showing the curvature of the reflecting surface in the horizontal direction. Further, lateral aberration diagrams of the entire optical system of this example are shown in FIGS. In this lateral aberration diagram, the angle shown at the center indicates (horizontal field angle, vertical field angle), and the lateral aberrations in the Y direction (meridional direction) and X direction (sagittal direction) at that field angle. Show.

The visual display device 1 includes an eyepiece optical system 2 and an image display surface 5.

The eyepiece optical system 2 includes a reflective optical element 4 and forms two eye points E for guiding the observation image to both eyes of the observer.

The reflective optical element 4 includes a reflecting mirror having a reflecting surface 4a and a transmitting surface 4b. As shown in FIG. 4, the reflecting surface 4a has a first curvature in the X-axis direction corresponding to a positive first value on the Y-axis, and a negative value on the Y-axis having the same absolute value as the first value. The shape is smaller than the second curvature in the X-axis direction corresponding to the second value.

The image display surface 5 is formed in a plane and displays an image in the plane.

In the visual display device 1, the light beam incident from the object plane 3 is reflected by the backward ray tracing, exits the eye point E as an exit pupil, that is, the observer's eyeball, enters the reflective optical element 4 from the transmission surface 4 b, and reflects the reflection surface 4 a. The reflection optical element 4 exits from the transmission surface 4 b and enters the image display surface 5.

In such a visual display device 1, when the observer puts his eyes on the two eye points E, the image displayed on the image display surface 5 is viewed as a virtual image at the position of the object surface 3 shown in FIG. 1. Can do.

7 is a view showing a state in which the lenticular lens 45 is disposed between the optical path of the image display surface 5 and the optical element 4, and FIG. 8 is an enlarged view of the vicinity of the lenticular lens 45. FIG.

As shown in FIG. 7, the lenticular lens 45 is disposed between the optical path of the image display surface 5 and the optical element 4, and distributes the image displayed on the image display surface 5 to the left and right eyes.

By having the lenticular lens 45, the image display surface 5 can alternately correspond to the left-eye pixel 5L and the right-eye pixel 5R one by one as shown in FIG. Can be observed.

FIG. 9 is a top view of a cross section including the optical paths of two central principal rays of the visual display device 1 according to the second embodiment. FIG. 10 is an enlarged plan view of a part of the visual display device 1 according to the second embodiment. 11 is a view of the positive direction of the X axis from the YZ section. FIG. 12 is a graph showing the horizontal curvature of the reflecting surface. Further, lateral aberration diagrams of the entire optical system of this example are shown in FIGS. In this lateral aberration diagram, the angle shown at the center indicates (horizontal field angle, vertical field angle), and the lateral aberrations in the Y direction (meridional direction) and X direction (sagittal direction) at that field angle. Show.

The visual display device 1 includes an eyepiece optical system 2, an image display surface 5, and a field lens 6.

The reflective optical element 4 includes a reflecting mirror having a reflecting surface 4a and a transmitting surface 4b. As shown in FIG. 10, the reflecting surface 4a has a first curvature in the X-axis direction corresponding to a positive first value on the Y-axis, and a negative value on the Y-axis having the same absolute value as the first value. The shape is smaller than the second curvature in the X-axis direction corresponding to the second value.

The field lens 6 is disposed on the reflective optical element 4 side of the image display surface 5 and closer to the image display surface 5 than the reflective optical element 4, and spreads light rays accurately.

In the visual display device 1, the light beam incident from the object plane 3 is reflected by the backward ray tracing, exits the eye point E as an exit pupil, that is, the observer's eyeball, enters the reflective optical element 4 from the transmission surface 4 b, and reflects the reflection surface 4 a. The reflection optical element 4 exits from the transmission surface 4 b, enters the second surface 6 b of the lens 6, exits from the first surface 6 a, and enters the image display surface 5.

In such a visual display device 1, when the observer puts his eyes on the two eye points E, the observer sees the image displayed on the image display surface 5 as a virtual image at the position of the object plane 3 shown in FIG. 9. Can do.

15 is a top view of a cross section including the optical paths of the two central principal rays of the visual display device 1 according to the third embodiment. FIG. 16 is an enlarged plan view of a part of the visual display device 1 according to the third embodiment. 17 is a view of the positive direction of the X axis from the YZ section. FIG. 18 is a graph showing the horizontal curvature of the reflecting surface, and FIG. 19 is a graph showing the horizontal curvature of the field lens. Further, lateral aberration diagrams of the entire optical system of this example are shown in FIGS. In this lateral aberration diagram, the angle shown at the center indicates (horizontal field angle, vertical field angle), and the lateral aberrations in the Y direction (meridional direction) and X direction (sagittal direction) at that field angle. Show.

The reflective optical element 4 includes a reflecting mirror having a reflecting surface 4a and a transmitting surface 4b. As shown in FIG. 18, the reflecting surface 4a has a first curvature in the X-axis direction corresponding to a positive first value on the Y-axis, and a negative value on the Y-axis whose absolute value is equal to the first value. The shape is smaller than the second curvature in the X-axis direction corresponding to the second value.

The field lens 6 is disposed on the reflective optical element 4 side of the image display surface 5 and closer to the image display surface 5 than the reflective optical element 4, and spreads light rays accurately. The second surface 6b, which is a transmission surface, is a free-form surface, and as shown in FIG. 19, the first curvature in the X-axis direction corresponding to the positive first value on the Y-axis is the first value. And a shape larger than the second curvature in the X-axis direction corresponding to the negative second value on the Y-axis having the same absolute value.

In the visual display device 1, the light beam incident from the object plane 3 is reflected by the backward ray tracing, exits the eye point E as an exit pupil, that is, the observer's eyeball, enters the reflective optical element 4 from the transmission surface 4 b, and reflects the reflection surface 4 a. The reflection optical element 4 exits from the transmission surface 4 b, enters the second surface 6 b that is the transmission surface of the field lens 6, exits from the first surface 6 a, and enters the image display surface 5.

In such a visual display device 1, when the observer puts his eyes on the two eye points E, the image displayed on the image display surface 5 is viewed as a virtual image at the position of the object plane 3 shown in FIG. 15. Can do.

FIG. 22 is a graph showing the difference S between the virtual image position due to diopter and the virtual image position due to convergence within the observation angle of view of Example 1, Example 2, and Example 3. The horizontal axis represents the virtual image position, and the vertical axis represents the vertical angle of view.

FIG. 22 shows that the convergence angle in the screen is constant in the first embodiment, the second embodiment, and the third embodiment. Therefore, the virtual image position 10 due to the convergence is a constant value indicated by a straight line of a two-point difference line. is there. The virtual image position 11 based on the diopter of Example 1 or the virtual image position 12 based on the diopter of Example 2 and the virtual image position 10 due to convergence have a predetermined difference S [m ⁻¹ ] according to the vertical angle of view. The difference between the virtual image position 11 due to the diopter of Example 1 and the virtual image position 10 due to convergence is S1, the difference between the virtual image position 12 due to the diopter according to Example 2 and the virtual image position 10 due to convergence is S2, and the visual difference of Example 3 The difference between the virtual image position 13 due to the degree and the virtual image position 10 due to the convergence is indicated by S3.

In Example 1, Example 2, and Example 3, the following conditional expression (4) is satisfied.
-0.5 ≤ S ≤ 0.5 (4)
However, S [m ⁻¹ ] is the difference between the virtual image position due to diopter and the virtual image position due to convergence within the observation angle of view.

The configuration parameters of Example 1 and Example 2 are shown below. In the table below, “RE” indicates a reflecting surface.

For the eccentric surface, the amount of eccentricity from the center O of the coordinate system in which the surface is defined (X, Y, and Z are X, Y, and Z, respectively) and the coordinate system defined by the center O The tilt angles (α, β, γ (°), respectively) of the coordinate system defining each surface centered on the X axis, the Y axis, and the Z axis are given. In this case, positive α and β mean counterclockwise rotation with respect to the positive direction of each axis, and positive γ means clockwise rotation with respect to the positive direction of the Z axis. Note that the α, β, and γ rotations of the central axis of the surface are performed by rotating the coordinate system defining each surface counterclockwise around the X axis of the coordinate system defined at the origin of the optical system. Then rotate it around the Y axis of the new rotated coordinate system by β and then rotate it around the Z axis of another rotated new coordinate system by γ. It is.

The eye width of the observer's eyes is indicated by the X eccentricity of the diaphragm St. In the optical path diagram in the horizontal section, the width is 60 mm.

Further, among the optical action surfaces constituting the optical system of each embodiment, when a specific surface and a subsequent surface constitute a coaxial optical system, a surface interval is given, in addition, the curvature radius of the surface, The refractive index and Abbe number of the medium are given according to conventional methods.

Also, the refractive index and the Abbe number are shown for d-line (wavelength 587.56 nm). The unit of length is mm. The eccentricity of each surface is expressed by the amount of eccentricity from the reference surface as described above.

Further, the shape of the free-form surface FFS used in the embodiment is defined by the following equation (a). Note that the Z axis of the defining equation is the axis of the free-form surface FFS. The coefficient term for which no data is described is zero.

Z = (r ² / R) / [1 + √ {1- (1 + k) (r / R) ² }]
₆₆
+ Σ C _j X ^m Y ⁿ (a)
^{j = 1}
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,
R: radius of curvature of apex k: conic constant (conical constant)
r = √ (X ² + Y ² )
It is.

The free-form surface term is
₆₆
ΣC _j X ^m Y ⁿ
^{j = 1}
= C ₁
+ C ₂ X + C ₃ Y
+ C ₄ X ² + C ₅ XY + C ₆ Y ²
+ C ₇ X ³ + C ₈ X ² Y + C ₉ XY ² + C ₁₀ Y ³
+ C ₁₁ X ⁴ + C ₁₂ X ³ Y + C ₁₃ X ² Y ² + C ₁₄ XY ³ + C ₁₅ Y ⁴
+ C ₁₆ X ⁵ + C ₁₇ X ⁴ Y + C ₁₈ X ³ Y ² + C ₁₉ X ² Y ³ + C ₂₀ XY ⁴
+ C ₂₁ Y ⁵
+ C ₂₂ X ⁶ + C ₂₃ X ⁵ Y + C ₂₄ X ⁴ Y ² + C ₂₅ X ³ Y ³ + C ₂₆ X ² Y ⁴
+ C ₂₇ XY ⁵ + C ₂₈ Y ⁶
+ C ₂₉ X ⁷ + C ₃₀ X ⁶ Y + C ₃₁ X ⁵ Y ² + C ₃₂ X ⁴ Y ³ + C ₃₃ X ³ Y ⁴
+ C ₃₄ X ² Y ⁵ + C ₃₅ XY ⁶ + C ₃₆ Y ⁷
・・・・・・
However, C _j (j is an integer of 1 or more) is a coefficient.

Example 1
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ -2000.00
s1 ∞ (diaphragm) 0.00 Eccentricity (1)
s2 FFS [1] 0.00 Eccentricity (2) 1.4918 57.4
s3 FFS [1] (RE) 0.00 Eccentricity (3) 1.4918 57.4
s4 FFS [1] 0.00 Eccentricity (2)
Image plane ∞ Eccentricity (4)

FFS [1]
C4 -1.4998e-003
C6 -1.5217e-003
C8 -6.5441e-007
C10 -3.2453e-008
C11 -7.4599e-009
C13 -1.5383e-008
C15 -1.7191e-009

Eccentric [1]
X 30.00 Y 0.00 Z 0.00
α 0.00 β 0.00 γ 0.00

Eccentric [2]
X 0.00 Y 0.00 Z 253.53
α -15.00 β 0.00 γ 0.00

Eccentric [3]
X 0.00 Y 0.00 Z 258.53
α -15.00 β 0.00 γ 0.00

Eccentric [4]
X 0.00 Y 78.23 Z 123.79
α -9.03 β 0.00 γ 0.00

Example 2
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ -2000.00
s1 ∞ (diaphragm) 0.00 Eccentricity (1)
s2 FFS [1] 0.00 Eccentricity (2) 1.4918 57.4
s3 FFS [1] (RE) 0.00 Eccentricity (3) 1.4918 57.4
s4 FFS [1] 0.00 Eccentricity (2)
s5 -100.00 -25.00 Eccentricity (4) 1.4918 57.4
s6 ∞ 0.00
Image plane ∞

FFS [1]
C4 -1.5382e-003
C6 -1.4836e-003
C8 -1.6606e-007
C10 1.2583e-007
C11 -5.5675e-009
C13 -1.0517e-008
C15 -2.9854e-009

Eccentric [1]
X 30.00 Y 0.00 Z 0.00
α 0.00 β 0.00 γ 0.00

Eccentric [2]
X 0.00 Y 0.00 Z 251.81
α -15.00 β 0.00 γ 0.00

Eccentric [3]
X 0.00 Y 0.00 Z 256.81
α -15.00 β 0.00 γ 0.00

Eccentric [4]
X 0.00 Y 74.88 Z 142.46
α -5.60 β 0.00 γ 0.00

Example 3
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface -∞ -2000.00
s1 ∞ (diaphragm) 0.00 Eccentricity (1)
s2 FFS [1] 0.00 Eccentricity (2) 1.4918 57.4
s3 FFS [1] (RE) 0.00 Eccentricity (3) 1.4918 57.4
s4 FFS [1] 0.00 Eccentricity (2)
s5 FFS [2] 0.00 Eccentricity (4) 1.5163 64.1
s6 ∞ 0.00 Eccentricity (5)
Image plane ∞ 0.00 Eccentricity (5)

FFS [1]
C4 -1.2220e-003
C6 -1.1722e-003
C8 -1.1146e-007
C10 7.6317e-008
C11 -2.8071e-009
C13 -6.9657e-009
C15 1.9899e-009
C68 1.0000e + 000

FFS [2]
C4 -2.9938e-003
C6 -5.9847e-003
C8 3.9268e-005
C10 -1.1160e-004
C11 -2.7861e-007
C13 -9.1271e-007
C15 -1.1595e-006
C17 -1.3077e-009

Eccentric [1]
X -30.00 Y 0.00 Z 0.00
α 0.00 β 0.00 γ 0.00

Eccentric [2]
X 0.00 Y 0.00 Z 295.00
α -17.00 β 0.00 γ 0.00

Eccentric [3]
X 0.00 Y 0.00 Z 300.00
α -17.00 β 0.00 γ 0.00

Eccentric [4]
X 0.00 Y 106.58 Z 145.83
α -2.74 β 0.00 γ 0.00

Eccentric [5]
X 0.00 Y 106.58 Z 130.83
α -5.12 β 0.00 γ 0.00

Next, the values of various data in each of the above examples are shown.

Various data Example 1 Example 2 Example 3
Fy -162.256 -166.476 -211.235
fx -165.655 -160.491 -202.545
fx / fy 1.015 0.964 0.959

23 is a graph showing the distortion of Example 1, FIG. 24 is a graph showing the distortion of Example 2, and FIG. 25 is a graph showing the distortion of Example 3. The thick solid line is distortion at an image height of 1.0 times in Example 1, the thin solid line is distortion at an image height of 0.7 times in Example 1, and the thick broken line is distortion at an image height of 1.0 times in Example 2. The thin broken line shows distortion at an image height of 0.7 times in Example 2, the thick dashed line shows distortion at an image height of 1.0 in Example 3, and the thin dotted line shows 0.7 times the image height in Example 3. It is a distortion of time.

Distorted by forward ray tracing. The object height is equivalent to X = 53.13, Y = 37.19, 5.8 inches 16: 9, and the unit of the graph is the angle (deg) of the observation beam at the pupil position. The convergence of both eyes is corrected to 0 (the inward angle 0.859 ° that coincides in 2 m ahead is 0).

As shown in FIG. 23 to FIG. 25, the images displayed on the visual display devices 1 of the first, second, and third embodiments are almost rectangular and the image distortion is reduced.

In the present embodiment, the image display surface is described by taking a plane as an example. However, it is preferable to make the image display surface a curved surface so that the convergence and the diopter can be further matched. Further, by making the display element compatible with 3D, naked-eye 3D display is possible. For example, even when the left and right viewpoints are separated by using a parallax barrier or a lenticular lens, the left and right viewpoints are formed by the eyepiece optical system, so that autostereoscopic viewing is possible. Furthermore, 3D display in which the liquid crystal shutter glasses and the image display surface are switched synchronously is also possible. In addition, a method of changing the polarization direction for each fine scanning line and a method of using circularly polarized light can be used as they are because the polarization plane is maintained by the eyepiece optical system.

Furthermore, in the embodiment, it is preferable that at least one reflecting surface is a semi-transmissive surface. By making the reflecting surface into a concave mirror shape, it becomes possible to observe a distant virtual image in which convergence and diopter coincide with each other even at an angle of view of 30 °. Furthermore, a semi-transmissive concave mirror can be provided at low cost by forming a thin film having a semi-transmissive action on the concave mirror by vacuum deposition or the like.

Moreover, it is preferable that the semi-transmissive surface has wavelength dependency. An image can be displayed without darkening an external image by using a semi-transmission surface having a wavelength dependency.

Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and embodiments configured by appropriately combining the configurations of the respective embodiments also fall within the scope of the present invention. Is.

Claims

One image display surface for displaying an observation image;
An eyepiece optical system for forming two eye points for guiding the observation image to both eyes of the observer;
With
The eyepiece optical system is
One reflective surface having a positive refractive index disposed to face the two eye points;
In order of back ray tracing from the two eye points to the image display surface,
The light beam emitted from the two eye points is reflected by the reflecting surface arranged so as to face the two eye points,
The light beam reflected by the reflecting surface is incident on the image display surface,
A visual display device characterized by satisfying the following conditional expression (1):
-1.0 ≤ S ≤ 1.0 (1)
However, S [m −1 ] is the difference between the virtual image position due to diopter and the virtual image position due to convergence within the observation angle of view.
The midpoint of the emission position of the central chief ray emitted from the two eye points is taken as the center of the coordinate system, and the central chief ray emitted from the two eye points goes from the center of the coordinate system to the point where it intersects the object plane. The direction is orthogonal to the positive direction of the Z axis, the line connecting the emission positions of the central principal rays that pass through the center of the coordinate system and exit from the two eye points, and the positive direction of the Z axis, and approaches the image display surface. In a coordinate system having a positive direction of the Y axis, a positive direction of the Y axis, and a positive direction of the X axis that forms a right hand system together with the positive direction of the Z axis and the positive direction of the Y axis
The visual display device according to claim 1, wherein the following conditional expression (2) is satisfied.
−300 <Fy <−100 (2)
However,
Fy is the focal length of the reflecting surface in the Y-axis direction.
The visual display device according to claim 2, wherein the following conditional expression (3) is satisfied.
0.9 <Fx / Fy <1.1 (3)
However,
Fx is the focal length of the reflecting surface in the X-axis direction,
Fy is the focal length of the reflecting surface in the Y-axis direction,
It is.
In the reflecting surface, the first curvature in the X-axis direction corresponding to the positive first value on the Y-axis corresponds to the negative second value on the Y-axis whose absolute value is equal to the first value. The visual display device according to claim 3, wherein the visual display device has a shape smaller than the second curvature in the X-axis direction.
The visual display device according to any one of claims 1 to 4, wherein the following conditional expression (4) is satisfied.
-0.5 ≤ S ≤ 0.5 (4)
However, S [m −1 ] is the difference between the virtual image position due to diopter and the virtual image position due to convergence within the observation angle of view.
The visual display device according to claim 1, wherein the reflecting surface is a free-form surface.
An optical element having a refractive action is disposed closer to the image display surface than the reflective surface,
The visual display device according to claim 1, wherein a transmission surface of the optical element is a free-form surface.
In the optical element, the first curvature in the X-axis direction corresponding to the positive first value on the Y-axis corresponds to the negative second value on the Y-axis having the same absolute value as the first value. The visual display device according to claim 7, wherein the visual display device has a shape smaller than the second curvature in the X-axis direction.
The visual display device according to any one of claims 1 to 8, further comprising a lenticular lens that distributes an image displayed on the image display surface to left and right eyes.
10. The visual display device according to claim 1, wherein the at least one reflecting surface is a semi-transmissive surface.
The visual display device according to claim 10, wherein the transflective surface has wavelength dependency.