JP6020113B2 - Virtual image display device - Google Patents

Description

  The present invention relates to a virtual image display device that presents an image formed by an image display element or the like to an observer, and more particularly to a virtual image display device suitable for a head-mounted display that is mounted on the observer's head.

  Various optical systems have been proposed as an optical system incorporated in a virtual image display device such as a head-mounted display (hereinafter also referred to as an HMD) that is worn on the observer's head (see Patent Documents 1 to 4).

  For virtual image display devices such as HMDs, it is desired to increase the angle of view of image light and reduce the weight of the device. In particular, reducing the thickness of the observer in the visual axis direction and bringing the center of gravity closer to the observer is important for improving the wearing feeling.

  Further, if the entire field of view of the observer is covered and only the image light can be seen, the state of the outside world is not known to the observer, which causes anxiety. In addition, new applications such as virtual reality are created by displaying images with the outside world. For this reason, there is a demand for a display that displays video light in an overlapping manner without obstructing the visual field of the outside world.

  Furthermore, in order to improve the wearing feeling of the observer and improve the appearance, it is generally desirable to approach the glasses, and the video display device can be placed beside the face without being placed above the eyes. Become desirable.

  In order to reduce the size of the optical system and not to disturb the field of view, the image display device is separated from the position of the observer's eye by forming the display image light once in the optical system to form an intermediate image, It is preferable to use a relay optical system that enlarges the intermediate image.

In Patent Documents 1 to 4, display optics having a small and simple configuration is obtained by using two prisms having an asymmetric curved surface (free curved surface) to correct a decentration aberration and form a relay optical system that forms an intermediate image. I have a system.
However, since this type of conventional optical system is not designed to show the external light to the observer, the prism in front of the eye is small and a sufficient external visual field cannot be obtained. Further, since the curved surface shape through which the external light is transmitted is not appropriate, the diopter for the external environment does not become zero, and blurring and distortion occur.

JP 2000-66106 A JP 2000-131614 A JP 2000-299853 A JP 2004-341411 A

  It is an object of the present invention to provide a small and lightweight virtual image display device having a see-through function for displaying external light and video light in a superimposed manner and having a wide angle of view and high performance.

  A virtual image display device according to the present invention is for visually recognizing image light and external light, and includes an image element that generates image light, a first prism including two or more non-axisymmetric curved surfaces, and 2 And an optical system including at least the second prism is a relay optical system that forms an intermediate image on an optical path from the first prism to the second prism, When the outside is visually recognized through the first surface and the third surface among the plurality of surfaces constituting the first prism, the diopter is substantially 0, and the first surface and the third surface are observed. The image light from the image element is totally reflected by the third surface, totally reflected by the first surface, reflected by the second surface, and then transmitted through the first surface. To reach the observation side.

  In the virtual image display device, an intermediate image is formed on the optical path from the first prism to the second prism, and in the first prism, the third surface, the first surface, and the second surface are all in order of two or more surfaces. The reflected image light passes through the first surface and reaches the viewer. Therefore, the first prism in front of the eye is thin, making the entire optical system small and lightweight, and with a wide angle of view and high performance. Display can be realized. Furthermore, the external light can be observed through the first surface and the third surface, and the diopter at that time is substantially 0. Focus and distortion can be reduced, and a wide field of view can be secured. In addition, the shape of the first prism in front of the observer's eyes is a shape that follows the face of the observer, and the center of gravity is close to the face, so that the design is excellent.

In a specific aspect of the present invention, in the virtual image display device, the expression of the surface shape is polynomially expanded with respect to the orthogonal coordinates x and y extending in the tangential direction from the origin, with the origin of each surface constituting the optical system as a reference. ^If the coefficient of the term x ^m · yn of the polynomial representing the k-th surface is Ak _{m, n} , the following conditions (1) to (3) are satisfied.
−5 × 10 ⁻² <A1 _2,0 + A1 _0,2 <−1 × 10 ⁻³ and −5 × 10 ⁻² <A3 _2,0 + A3 _0,2 <−1 × 10 ⁻³ (1)
| A3 _2,0 −A3 _0,2 | <1 × 10 ⁻² (2)
| A1 _2,0 −A3 _2,0 | <5 × 10 ⁻³ and | A1 _0,2 −A3 _0,2 | <5 × 10 ⁻³ (3)
In the above, the local coordinates (x, y, z) including the orthogonal coordinates x and y of each surface have a certain point on the curved surface as the origin, the z-axis in the normal direction of the surface, and the tangential direction of the surface The x axis and the y axis are taken. The origin of the curved surface is, for example, a position where the center of the light beam passes.

In the present invention, the first surface and the third surface related to observation of not only image light but also external light are free curved surfaces, and both surfaces are concave, thereby effectively using the degree of freedom of these curved surface shapes. And succeeded in obtaining a high-quality optical system. Characterizing the functions of the first and third surfaces is the curvature of the curved surface, and the curvature near the origin is mainly determined by the values of the coefficients Ak _2,0 and Ak _0,2 (k = 1, 3). It is important to set the values of the coefficients Ak _2,0 and Ak _0,2 appropriately.

Condition (1) defines the magnitude of the curvature of the first surface and the curvature of the third surface in the vicinity of the origin. The fact that these values A1 _2,0 , A1 _0,2 , A3 _2,0 , A3 _0,2 are negative means that the first surface or the third surface is concave with respect to the observer. Represents. If the upper limit of condition (1) is exceeded, the shape becomes nearly flat, and it will not work effectively for correcting aberrations of image light even if there is no problem in observing external light. If the lower limit of the condition (1) is exceeded, the curvature becomes too strong and aberration correction becomes difficult, and the position of the prism of the relay optical system becomes close to the face, which impairs wearing comfort.

  Condition (2) defines the difference between the curvature of the third surface in the x-axis direction and the curvature in the y-axis direction. If the upper limit of condition (2) is exceeded, astigmatism that occurs on the third surface becomes too large, and aberration correction becomes difficult.

Condition (3) defines a difference between the curvature of the first surface and the curvature of the third surface in the x-axis direction and the y-axis direction, and affects the diopter of the prism with respect to external light. The diopter Dx in the x-axis direction and the diopter Dy in the y-axis direction on the optical axis of the prism are expressed as follows:
Dx = 2000 (N−1) (A1 _2,0 −A3 _2,0 + (2T (N−1) / N) × A1 _2,0 × A3 _2,0 )
_{Dy = 2000 (N-1)} (A1 0,2 -A3 0,2 + (2T (N-1) / N) × A1 0,2 × A3 0,2)
Given in.
In general, since the distance diopter error feels unpleasant when it exceeds ± 1D, it is desirable to suppress the diopter of the prism to ± 1D. Since the diopter on the optical axis is related to the thickness of the prism and the refractive index as described above, it cannot be determined only by the value of the aspheric coefficient, but the coefficient satisfies the condition (3). If so, the diopter on the optical axis can be suppressed to a range of ± 1D.

  By making the first surface and the third surface satisfy the above conditions (1) to (3), the aberration correction of both the external light and the image light is favorably performed, and excellent image quality can be obtained. it can.

  In still another aspect of the present invention, the first prism and the second prism having a plurality of surfaces are formed separately.

  In another aspect of the present invention, a half mirror is formed on the second surface, the image light is presented to the observer, a light transmitting member is integrally disposed outside the second surface, and the diopter for external light is increased. It is set to substantially 0, and external light and video light are superimposed and presented to the observer. In this case, it is possible to reduce the defocus and distortion of the external light visually recognized through the second surface.

  In still another aspect of the present invention, the light transmission member has a first transmission surface and a second transmission surface on the observer side, a third transmission surface on the outside side, and a second surface of the first prism. The second transmission surface of the light transmission member has substantially the same curved surface shape, and the second surface and the second transmission surface are integrated. In this case, the surfaces can be joined and integrated, and a continuous surface can be formed on each of the first surface and the third surface.

  In still another aspect of the present invention, the first surface, the second surface, and the third surface have symmetrical shapes with a reference surface including an optical path passing through the first surface, the second surface, and the third surface interposed therebetween.

  In still another aspect of the present invention, the distance between the first surface and the third surface is 5 mm or more and 15 mm or less. In this case, the size of the first prism covering the front of the eye can be sufficiently increased by being 5 mm or more, and an increase in weight can be suppressed by being 15 mm or less.

  In still another aspect of the present invention, the inclination angle of the second surface with respect to the first surface is 20 ° or more and 40 ° or less. In this case, when the tilt angle is in the above range, it becomes easy to guide the image light to the eye with an appropriate number of reflections and reflection angles.

  In still another aspect of the present invention, the video device is integrally fixed to the second prism so as to face the image light incident surface of the second prism. In this case, the video device can be assembled in a space-saving manner, and the virtual image display device can be reduced in size.

  In still another aspect of the present invention, the second prism has a plurality of surfaces, and an intermediate image is formed by the video device, the plurality of surfaces of the second prism, and the fourth surface that is the light incident surface of the first prism. .

  In still another aspect of the present invention, the optical system including the first prism covers a portion of the front of the viewer's eyes when worn and a portion where the front of the eyes is not covered exists.

  In still another aspect of the present invention, the video element emits signal light that emits signal light modulated in accordance with an image, and emits scanning light by scanning the signal light incident from the signal light forming part. A scanning optical system.

It is a perspective view explaining the virtual image display device of an embodiment. It is a perspective view explaining the main body structure of a virtual image display apparatus. (A) is sectional drawing of the planar view of the main-body part of the 1st display apparatus which comprises a virtual image display apparatus, (B) is a front view of a main-body part. It is sectional drawing explaining the optical surface and optical path in the prism in a 1st display apparatus. 1 is a diagram illustrating an optical system according to Example 1. FIG. (A)-(F) is a figure explaining the aberration of the optical system of Example 1. FIG. (A)-(F) is a figure explaining the aberration of the optical system of Example 1. FIG. FIG. 6 is a diagram illustrating an optical system of Example 2. (A)-(F) is a figure explaining the aberration of the optical system of Example 2. FIG. (A)-(F) is a figure explaining the aberration of the optical system of Example 2. FIG. FIG. 6 is a diagram illustrating an optical system of Example 3. (A)-(F) is a figure explaining the aberration of the optical system of Example 3. FIG. (A)-(F) is a figure explaining the aberration of the optical system of Example 3. FIG. FIG. 6 is a diagram illustrating an optical system of Example 4. (A)-(F) is a figure explaining the aberration of the optical system of Example 4. FIG. (A)-(F) is a figure explaining the aberration of the optical system of Example 4. FIG. It is a figure explaining the virtual image display apparatus of a modification. It is a figure explaining the virtual image display apparatus of another modification. (A) is a perspective view explaining another example of a light guide device and a virtual image display device using the same, and (B) is a front view.

  Hereinafter, a virtual image display device according to an embodiment of the present invention will be described in detail with reference to the drawings.

[A. Appearance of virtual image display device)
A virtual image display device 100 according to the embodiment shown in FIG. 1 is a head-mounted display having an appearance like glasses, and allows an observer wearing the virtual image display device 100 to visually recognize image light corresponding to a virtual image. In addition, it is possible for the observer to visually recognize or observe the external image with see-through. The virtual image display device 100 is added to a transparent member 101 that covers the front of the observer's eyes, a frame 102 that supports the transparent member 101, and a portion extending from a cover portion on both the left and right sides of the frame 102 to a rear vine portion (temple). First and second built-in device sections 105a and 105b are provided. Here, the see-through member 101 is a thick and curved optical member (transparent eye cover) that covers the front of the observer's eyes, and is divided into a first optical portion 103a and a second optical portion 103b. The first display device 100A, which is a combination of the left first optical portion 103a and the first built-in device portion 105a in the drawing, is a portion that forms a virtual image for the right eye, and functions alone as a virtual image display device. Further, the second display device 100B in which the second optical portion 103b on the right side in the drawing and the second built-in device portion 105b are combined is a portion that forms a virtual image for the left eye, and functions alone as a virtual image display device. .

[B. Display device structure]
As shown in FIGS. 2, 3 (A), 3 (B), and the like, the first display device 100 </ b> A includes a projection see-through device 70 and an image display device 80. Among these, the projection see-through device 70 includes a first prism 10 that is a light guide member, a second prism 20, and a light transmitting member 50. The first prism 10 and the light transmission member 50 are joined and integrated, and for example, are firmly fixed to the lower side of the frame 61 so that the upper surface 10e of the first prism 10 and the lower surface of the frame 61 are in contact with each other. The second prism 20 is fixed to the first prism 10 via a support member (not shown) in a state of being separated from the first prism 10. The first prism 10 and the light transmitting member 50 in the projection fluoroscopic device 70 correspond to the first optical portion 103a in FIG. 1, and the second prism 20 of the projection fluoroscopic device 70 and the image display device 80 are as shown in FIG. This corresponds to the first built-in device unit 105a in FIG. Note that the second display device 100B shown in FIG. 1 has the same structure as the first display device 100A and is simply flipped left and right, and thus detailed description of the second display device 100B is omitted.

  In the projection see-through device 70, the first prism 10 is an arc-shaped member that is curved along the face in plan view. The first prism 10 has a first surface S11, a second surface S12, a third surface S13, and a fourth surface S14 as side surfaces having an optical function. Among these, the second surface S12 is disposed between the first surface S11 and the third surface S13 and on the front side of the eye EY, and between the first surface S11 and the third surface S13, the second prism. The fourth surface S14 is disposed on the 20 side. The first prism 10 has a first side surface 10e and a second side surface 10f that are adjacent to the first to fourth surfaces S11 to S14 and face each other.

  In the first prism 10, the first surface S11 is a free-form surface having the emission side optical axis AXO parallel to the Z axis as a central axis or a reference axis, and the second surface S12 is a reference surface SR parallel to the XZ plane. The third curved surface S13 is a free curved surface with the optical axis AX1 included and inclined with respect to the Z axis as the central axis or the reference axis, and the third surface S13 is a free curved surface with the emission side optical axis AXO as the central axis or the reference axis. The fourth surface S14 is a free-form surface having the optical axis AX3 included in the reference surface SR parallel to the XZ plane and inclined with respect to the Z axis as a central axis or a reference axis. The first to fourth surfaces S11 to S14 described above extend in the horizontal (or horizontal) direction, are parallel to the XZ plane, and sandwich the reference plane SR through which the optical axes AX1 to AX3 and the like pass, and the vertical (or vertical) Y axis. It has a symmetrical shape with respect to the direction.

  The first prism 10 is formed of a resin material that exhibits high light transmittance in the visible range. The first prism 10 has a block-like member integrally formed by, for example, injection molding as the main body portion 10s, and can guide and emit the image light GL and can see through the external light HL. To. The main body portion 10s is formed, for example, by injecting a thermoplastic resin material into a molding die and curing it.

  In the first prism 10, the first surface S11 functions as a refracting surface that emits the image light GL to the outside of the first prism 10, and also functions as a total reflection surface that totally reflects the image light GL on the inner surface side. The first surface S11 is arranged in front of the eye EY and has a concave shape with respect to the observer. The first surface S11 can also cover the main body portion 10s with a hard coat layer for the purpose of preventing damage to the surface and preventing a reduction in the resolution of the image. This hard coat layer is formed by forming a coating agent made of resin or the like on the lower ground of the main body portion 10s by dipping or spray coating.

  The second surface S12 has a half mirror layer 15. The half mirror layer 15 is a light-transmissive reflective film (that is, a semi-transmissive reflective film). The half mirror layer (semi-transmissive reflective film) 15 is formed not on the entire second surface S12 but on the partial area PA. That is, the half mirror layer 15 is formed on the partial area PA in which the entire area QA where the second surface S12 extends is narrowed mainly in the vertical direction. More specifically, the partial area PA is arranged on the center side in the vertical Y-axis direction, and is arranged almost entirely in the direction along the horizontal reference plane SR. The half mirror layer 15 is formed by forming a metal reflective film or a dielectric multilayer film on the partial area PA in the lower ground of the main body portion 10s. The reflectance of the half mirror layer 15 with respect to the video light GL is set to be 10% or more and 50% or less in the assumed incident angle range of the video light GL from the viewpoint of facilitating observation of the external light HL by see-through. The reflectance of the half mirror layer 15 of the specific embodiment with respect to the video light GL is set to 20%, for example, and the transmittance with respect to the video light GL is set to 80%, for example.

  The third surface S13 functions as a total reflection surface that totally reflects the video light GL on the inner surface side. The third surface S13 can also cover the main body portion 10s with a hard coat layer for the purpose of preventing damage to the surface and preventing a reduction in the resolution of the image. The third surface S13 is arranged in front of the eye EY, and has a concave shape with respect to the observer, like the first surface S11, and allows the first surface S11 and the third surface S13 to pass therethrough. When the external light HL is viewed, the diopter is substantially zero.

  The fourth surface S14 functions as a refracting surface (light incident surface) for allowing the image light GL to enter the first prism 10. The fourth surface S14 can also cover the main body portion 10s with a hard coat layer for the purpose of preventing damage to the surface and preventing a reduction in the resolution of the image. Furthermore, the main body portion 10s can be covered with a multilayer film for the purpose of suppressing ghosts by preventing reflection.

  Of the projection fluoroscope 70, the second prism 20 is a member that bends the optical path. The second prism 20 has a fifth surface S21, a sixth surface S22, a seventh surface S23, and an eighth surface S24 as side surfaces having an optical function. Among these, the fifth surface S21 and the sixth surface S22 are substantially opposed, and the seventh surface S23 and the eighth surface S24 are substantially opposed. The second prism 20 has a first side surface 20e and a second side surface 20f that are adjacent to the fifth to eighth surfaces S21 to S24 and face each other. Among the above, the fifth surface S <b> 21 faces the fourth surface S <b> 14 of the adjacent first prism 10.

  In the second prism 20, the fifth surface S21 is a free-form surface having an optical axis AX4 that is included in the reference surface SR parallel to the XZ plane and is inclined with respect to the Z axis as a central axis or a reference axis. The sixth surface S22 is a free-form surface having a bisector of two optical axes AX4 and AX5 included in the reference surface SR parallel to the XZ plane and inclined with respect to the Z axis as a central axis or a reference axis. The seventh surface S23 is a free-form surface having a bisector of two optical axes AX5 and AX6 included in the reference surface SR parallel to the XZ plane and inclined with respect to the Z axis as a central axis or a reference axis. The surface S24 is a free-form surface having the optical axis AX6 included in the reference surface SR parallel to the XZ plane and inclined with respect to the Z axis as a central axis or a reference axis. Here, the optical axis AX4 coincides with the optical axis AX3 of the first prism 10, and the optical axis AX6 coincides with the incident side optical axis AXI from the image display device 80. The fifth to eighth surfaces S21 to S24 described above extend in the horizontal (or lateral) direction, are parallel to the XZ plane, and sandwich the reference plane SR through which the optical axes AX4 to AX6 and the like pass, and the vertical (or vertical) Y axis. It has a symmetrical shape with respect to the direction.

  Similar to the first prism 10, the second prism 20 is formed of a resin material exhibiting high light transmittance in the visible range. The second prism 20 has a block-shaped member integrally formed by, for example, injection molding as the main body portion 20 s, and allows the image light GL to be incident and guided and transmitted to the first prism 10. The main body portion 20s is formed by, for example, injecting a thermoplastic resin material into a molding die and curing it.

  In the second prism 20, the fifth surface S 21 functions as a refracting surface that emits the image light GL to the outside of the second prism 20. The fifth surface S21 can also cover the main body portion 20s with a hard coat layer for the purpose of preventing damage to the surface and preventing a reduction in the resolution of the image. Furthermore, the main body portion 20s can be covered with a multilayer film for the purpose of suppressing ghosts by preventing reflection.

  The sixth surface S22 and the seventh surface S23 are covered with a mirror layer 27, which is a non-transmissive reflective coat, and are used as reflective surfaces (broadly defined total reflection surfaces) that substantially reflect the image light GL on the inner surface side. Function. In addition, by adjusting the refractive index of the main body portion 20s or the reflection angle at the sixth or seventh surface S22, S23, a total reflection surface that totally reflects the image light GL on the inner surface side of these surfaces S22, S23. It can also function as a (totally reflecting surface in a narrow sense).

  The eighth surface S24 functions as a refracting surface on which the image light GL enters the second prism 20. The eighth surface S24 can be formed by coating the main body portion 20s with a multilayer film for the purpose of suppressing ghosts by preventing reflection.

  Since the second prism 20 re-images the video light GL emitted from the image display device 80 along the incident side optical axis AXI, the video light GL from the image display device 80 is appropriately converged in the second prism 20. Then, the light is incident on the first prism 10 through the fourth surface S14 of the first prism 10. That is, the second prism 20 is a relay optical system for re-imaging the image light or the image light emitted from each point on the image plane (display position) OI of the image display element 82 into the first prism 10. is there. In this case, the fourth surface S14 of the first prism 10 also functions as a part of the relay optical system by cooperating with the second prism 20.

  The light transmitting member 50 has high light transmittance in the visible range, is formed of a resin material having substantially the same refractive index as the first prism 10, and is fixed integrally with the first prism 10 as an auxiliary prism. Yes. The light transmitting member (auxiliary prism) 50 is a member that assists the see-through function of the first prism 10, and includes a first transmitting surface S51, a second transmitting surface S52, and a third transmitting surface as side surfaces having an optical function. Surface S53. Here, the second transmission surface S52 is disposed between the first transmission surface S51 and the third transmission surface S53. The first transmission surface S51 is on a curved surface obtained by extending the first surface S11 of the first prism 10, and the second transmission surface S52 is bonded to the second surface S12 of the first prism 10 by the adhesive CC and integrated. The third transmission surface S53 is on a curved surface obtained by extending the third surface S13 of the first prism 10.

  The first prism 10 is connected to a second prism 20 described later, and supports the second prism 20. The second prism 20 is connected to an image display device 80 described later and supports the image display device 80. The light incident side of the first prism 10 is covered with a light shielding member 63 together with the second prism 20 and the like. The upper and lower ends of the first prism 10 are also covered with the light shielding member 63. In the vicinity of the first and second prisms 10 and 20, an additional light shielding unit for preventing external light from entering can be provided. The light shielding part can be composed of, for example, a light shielding coating or a light scattering layer.

  The image display device 80 includes a video display element 82 that is a self-luminous display device, and a drive control unit 84 that controls the operation of the video display element 82.

  The video display element 82 is a video element formed by, for example, an organic EL (Organic Electro-Luminescence) or OLED (Organic light-emitting diode), and forms image light to be displayed such as a moving image. The drive control unit 84 outputs an image signal or a drive signal to the video display element 82, thereby forming color image light as a source of a moving image or a still image as a transmittance pattern. Note that the video display element (video element) 82 of the image display device 80 is integrally fixed to the second prism 20 so as to face the eighth surface S24 that is the image light incident surface of the second prism 20. .

[C. (Optical path for image light, etc.)
Hereinafter, an optical path of the image light GL and the like in the virtual image display device 100 will be described.

  The image light GL emitted from the image display element (image element) 82 changes its direction while being converged by the second prism 20, and is provided on the first prism 10 and has a fourth surface S 14 having a relatively strong negative refractive power. Is incident on.

  The image light GL that has passed through the fourth surface S14 of the first prism 10 advances while converging, is incident on the third surface S13 having a relatively weak positive refractive power, is totally reflected, and has a relatively weak negative refractive power. Is incident on the first surface S11 having total reflection. The image light GL forms an intermediate image in the prism 10 before and after passing through the third surface S13 by the relay optical systems 20 and S14 including the second prism 20 and the fourth surface S14 of the first prism 10. Form. The image plane II of the intermediate image corresponds to the image plane (display position) OI of the video display element 82, but is folded back on the third surface S13.

  The image light GL totally reflected by the first surface S11 is incident on the second surface S12. In particular, the image light GL incident on the half mirror layer 15 is partially transmitted through the half mirror layer 15 while partially transmitting. And is incident again on the first surface S11 and passes therethrough. The half mirror layer 15 acts as a layer having a relatively strong positive refractive power with respect to the image light GL reflected here. Further, the first surface S11 acts as having negative refractive power with respect to the video light GL passing through the first surface S11.

  The video light GL that has passed through the first surface S11 enters the pupil of the observer's eye EY as a substantially parallel light beam. That is, the observer observes the image formed on the video display element 82 with the video light GL as a virtual image.

  On the other hand, of the external light HL, the light incident on the + X side from the second surface S12 of the first prism 10 passes through the third surface S13 and the first surface S11. It cancels out and aberrations are corrected. That is, the observer observes an external image with little distortion through the first prism 10. Similarly, of the external light HL, the light incident on the −X side with respect to the second surface S12 of the first prism 10, that is, the light incident on the light transmission member 50, is connected to the third transmission surface S53 provided thereon. When passing through the first transmission surface S51, the positive and negative refractive powers are canceled and aberration is corrected. That is, the observer observes an external image with little distortion through the light transmission member 50. Further, among the external light HL, light incident on the light transmission member 50 corresponding to the second surface S12 of the first prism 10 has positive and negative refraction when passing through the third transmission surface S53 and the first surface S11. The force is canceled and the aberration is corrected. That is, the observer observes an external image with little distortion through the light transmission member 50. The second surface S12 of the first prism 10 and the second transmission surface S52 of the light transmission member 50 both have substantially the same curved surface shape, have substantially the same refractive index, and the gap between them is substantially the same. It is filled with an adhesive layer (adhesive) CC having the same refractive index. That is, the second surface S12 of the first prism 10 and the second transmission surface S52 of the light transmission member 50 do not act as a refracting surface with respect to the external light HL.

  However, since the external light HL incident on the half mirror layer 15 is partially reflected while partially transmitting through the half mirror layer 15, the transmittance decreases. Since the video light GL is incident from the video display element 82 side, the observer observes the external image together with the image formed on the video display element 82 in the direction of the half mirror layer 15.

  Of the image light GL propagated in the first prism 10 and incident on the second surface S <b> 12, the image light GL not reflected by the half mirror layer 15 is incident on the light transmitting member 50, but is provided on the light transmitting member 50. Returning to the first prism 10 is prevented by an antireflection portion (not shown). That is, the image light GL that has passed through the second surface S12 is prevented from returning to the optical path and becoming stray light. In addition, the external light HL incident from the light transmitting member 50 side and reflected by the half mirror layer 15 is returned to the light transmitting member 50, but the first antireflection portion (not shown) provided in the light transmitting member 50 performs the first processing. A single prism 10 is prevented from being emitted. That is, it is possible to prevent the external light HL reflected by the half mirror layer 15 from returning to the optical path and becoming stray light.

[D. (Specifying method of optical surface and optical path)
FIG. 4 is a diagram illustrating the optical axes AX1 to AX3 and local coordinates in the first prism 10. In the following description, in consideration of convenience of evaluation and expression of the optical system, an optical surface and an optical path are defined in the backward direction from the observer's eye EY toward the image display device 80. In an actual optical system, light emitted from the image display element 82 sequentially passes through the second prism 20 and the first prism 20 and reaches the eye EY. However, in this state, it is difficult to evaluate the optical system. Therefore, evaluation and design are performed on the assumption that light from an infinitely distant light source enters the first prism 10 through the diaphragm at the position of the eye EY and forms an image on the image display element 82 through the second prism 20. The optical system data described in detail below are also displayed in that order. In addition, about the light transmission member 50 joined to the prism 10 and used integrally, the shape of the 1st prism 10 is extended and description is abbreviate | omitted.

  In the illustrated prism 10, the optical axis of the first surface S11 coincides with the exit-side optical axis AXO, and the local coordinates (x, y, z) of the first surface S11 are the global coordinates (X, Y, Z). ), And has an origin on the first surface S11. That is, the z direction of the local coordinates is on the emission side optical axis AXO and is the traveling direction (the backward direction of the light beam), and the y direction of the local coordinates is parallel to the Y direction of the entire coordinates. . Also in each subsequent surface, the y direction of the local coordinates is parallel to the Y direction of the global coordinates.

  The optical axis of the second surface S12 is appropriately tilted with respect to the emission-side optical axis AXO, and the local coordinates of the second surface S12 are appropriately rotated around the Y axis with respect to the overall coordinates. It has been translated and has an origin on the second surface S12. The z direction of the local coordinates of the second surface S12 is an intermediate direction between the emission side optical axis AXO and the optical axis AX1 at the center of the light beam from the second surface S12 toward the first surface S11.

  The optical axis of the third surface S13 coincides with the emission side optical axis AXO, and the local coordinates of the third surface S13 are in a translational relationship with the overall coordinates, and are an extended surface of the third surface S13, that is, a third transmission surface. It has an origin on S53.

  As described above, the intermediate direction between the optical axis AX1 at the light beam center from the second surface S12 toward the first surface S11 and the optical axis AX2 at the light beam center from the first surface S11 toward the third surface S13 is This coincides with the normal direction of the first surface S11 at the center of the light beam on the first surface S11 (intersection of the optical axes AX1 and AX2). The intermediate direction between the optical axis AX2 at the center of the light beam from the first surface S11 toward the third surface S13 and the optical axis AX3 at the center of the light beam from the third surface S13 toward the fourth surface S14 is the third direction. This coincides with the normal direction of the third surface S13 at the center of the light beam on the surface S13 (intersection of the optical axes AX2 and AX3).

  In the optical path from the third surface S13 to the next fourth surface S14, the local coordinates correspond to the traveling direction (the backward direction of the light beam). That is, the z direction of the local coordinates from the third surface S13 to the fourth surface S14 coincides with the optical axis AX3 at the center of the light beam, and the y direction of the local coordinates is parallel to the Y direction of the overall coordinates. Yes.

  The origin of the local coordinates of the fourth surface S14 is on the fourth surface S14, although not shown. Further, the z direction of the local coordinates of the fourth surface S14, that is, the optical axis of the fourth surface S14 coincides with the optical axis AX3.

  Although detailed illustration is omitted in the second prism 20, the origin of the local coordinates of the fifth surface S21 is on the fifth surface S21, and the z direction of the local coordinates is the optical axis AX4 of the fifth surface S15. It is parallel to. The origin of the local coordinates of the sixth surface S22 is at the intersection of the optical axes AX4 and AX5, and the z direction is a bisector of AX4 and AX5. Similarly, the origin of the local coordinates of the seventh surface S23 is at the intersection of the optical axes AX5 and AX6, and the z direction is a bisector of AX5 and AX6.

[E. Desirable characteristics of optical surface)
The shape of the first surface S11 of the prism 10 is z = Σ {A1 _{m, n} · (x ^m · y ⁿ )} using the local coordinates (x, y, z) of the first surface S11 (4).
Here, A1 _{m, n} is the coefficient m, n of the m · n-th term expanded in polynomial expression, and is represented by an integer of 0 or more.

The shape of the second surface S12 of the prism 10 is obtained by using the local coordinates (x, y, z) of the second surface S12, z = Σ {A2 _{m, n} · (x ^m · y ⁿ )} (5)
Here, A2 _{m, n} is represented by a coefficient of the m · n-th term that has been polynomial-expanded.

The shape of the third surface S13 of the prism 10 is z = Σ {A3 _{m, n} · (x ^m · y ⁿ )} using the local coordinates (x, y, z) of the third surface S13 (6).
Here, A3 _{m, n} is expressed by a coefficient of the m · n-th term expanded in polynomial form.

In the present embodiment, the first to third surfaces S11 to S13 of the prism 10 are
−5 × 10 ⁻² <A1 _2,0 + A1 _0,2 <−1 × 10 ⁻³ and −5 × 10 ⁻² <A3 _2,0 + A3 _0,2 <−1 × 10 ⁻³ (1)
| A3 _2,0 −A3 _0,2 | <1 × 10 ⁻² (2)
| A1 _2,0 −A3 _2,0 | <5 × 10 ⁻³ and | A1 _0,2 −A3 _0,2 | <5 × 10 ⁻³ (3)
The following three conditions are satisfied. By setting the shapes of the first to third surfaces S11 to S13 so as to satisfy these three conditions, the aberration correction of both the external light HL and the video light GL is favorably performed, and excellent image quality is brought about. Can do.

  The distance between the first surface S11 and the third surface S13 of the prism 10 is not less than 5 mm and not more than 15 mm. Further, the inclination angle of the second surface S12 with respect to the first surface S11 is 20 ° or more and 40 ° or less.

  The fifth surface S21 to the eighth surface S28 of the second prism 20 are provided for adjusting the optical path and correcting aberrations more precisely.

  In the virtual image display device 100 of the present embodiment, an intermediate image is formed on the optical path from the first prism 10 to the second prism 20, and in the first prism 10, the third surface S <b> 13, the first surface S <b> 11, Since the image light GL totally reflected by two or more surfaces in the order of the two surfaces S12 passes through the first surface S11 and reaches the eyes EY of the observer, the first prism 10 and the like are thinned to make the entire optical system small. It is possible to realize a high-performance display with a wide angle of view while making it light and lightweight. Further, the external light HL can be observed, for example, through the first surface S11 and the third surface S13, and the diopter at that time is set to approximately 0. Therefore, when the external light HL is observed with see-through, The defocus and distortion of the external light HL can be reduced, and a wide field of view can be secured. In addition, the shape of the first prism 10 in front of the eyes is a shape along the face of the observer, the center of gravity is close to the face, and the design is excellent.

〔Example〕
Embodiments of a projection fluoroscopic apparatus incorporated in a virtual image display apparatus according to the present invention will be described below. The symbols used in each example are summarized below.
SPH: Pupil FFSk: Free curved surface (k in prism = surface number)
SPH: spherical surface or flat surface (protective glass surface)
R: radius of curvature T: spacing between top surfaces of axis Nd: refractive index with respect to d-line of optical material Vd: Abbe number TLY with respect to d-line of optical material: tilt angle (°) of optical axis in transverse plane (XZ section) of specific surface
(TLY may change before and after a specific surface)
DCX: Deviation amount of the optical axis in the X-axis direction in the cross section (XZ cross section) of the specific surface

Example 1
Table 1 below shows data of optical surfaces constituting the first and second prisms of the projection fluoroscopic apparatus of Example 1. For example, FFS1 means the first surface S11, FFS2 means the second surface S12, and FFS3 means the third surface S13.
[Table 1]
No Type RT Nd Vd
1 SPH ∞ 20.00
2 FFS1 -93.539 5.50 1.525 55.95
3 FFS2 -52.343 -5.50 1.525 55.95
4 FFS1 -93.539 9.00 1.525 55.95
5 FFS3 -93.539 -12.00 1.525 55.95
6 FFS4 -7.126 -2.00
7 FFS5 -25.191 -12.00 1.525 55.95
8 FFS6 48.793 10.00 1.525 55.95
9 FFS7 -19.626 -11.00 1.525 55.95
10 FFS8 955.532 -3.00
11 SPH ∞ -1.60 1.458 67.82
12 Image plane

Table 2 below shows the optical axis tilt angle (tilt) TLY and the optical axis shift amount (decenter) DCX in the cross section of the optical surface in the prism constituting the first embodiment.
[Table 2]
No Type TLY (front) DCX (back) TLY (back)
2 FFS1 0 0 0
3 FFS2 -28 0 28
4 FFS1 0 0 0
5 FFS3 0 20.367 -42.19
6 FFS4 0 0 0
7 FFS5 0 0 0
8 FFS6 -21 0 -21
9 FFS7 -22 0 -22
10 FFS8 0 0 0

Table 3 below shows coefficients Akm _{, n} obtained by polynomial expansion of a free-form surface for each optical surface in the prism constituting the first embodiment. In Table 3, the symbols m and n mean variables or orders in the coefficient Akm _{, n} . The symbol FFSk (k = 1 to 8) means the k-th surface among the first to eighth surfaces S11 to S14 and S21 to S24 which are free-form surfaces. The coefficient _{Ak m, n} denotes the coefficient of each term ^x m · ^{y n} constituting a polynomial representative of the k-th surface of interest.
[Table 3]
mn FFS1 FFS2 FFS3 FFS4
2 0 -6.783E-03 -9.098E-03 -6.783E-03 1.269E-02
0 2 -5.345E-03 -9.552E-03 -5.345E-03 -7.017E-02
3 0 4.276E-05 -2.399E-05 4.276E-05 7.330E-03
1 2 -9.264E-05 -8.110E-05 -9.264E-05 3.860E-03
4 0 -1.783E-06 1.365E-06 -1.783E-06 1.279E-03
2 2 -2.447E-06 -3.951E-05 -2.447E-06 3.043E-03
0 4 -1.120E-06 -1.496E-06 -1.120E-06 1.010E-03

mn FFS5 FFS6 FFS7 FFS8
2 0 -2.737E-02 1.107E-02 -1.520E-02 -1.011E-03
0 2 -1.985E-02 1.025E-02 -2.548E-02 5.233E-04
3 0 7.723E-03 7.736E-05 -2.485E-04 5.481E-04
1 2 1.182E-03 3.478E-04 -4.576E-04 -7.339E-04
4 0 8.934E-04 -3.599E-05 -1.461E-05 -2.227E-03
2 2 3.557E-03 1.386E-05 7.156E-06 -6.654E-04
0 4 -7.538E-03 -1.098E-04 -8.726E-06 -2.124E-03
In the above Table 3 and the following tables, the numerical value after E means a decimal exponent part, for example, “−6.511E-03” means −6.511 × 10 ⁻⁰³ .

  FIG. 5 is a sectional view of the projection see-through device 70 of the first embodiment. However, the light flux is shown not only on the reference surface SR but also out of the reference surface SR in the Y direction. The first prism 10 of the projection fluoroscopic device 70 includes a first surface S11 having a weak negative refractive power, a second surface S12 having a relatively strong positive refractive power, and a first surface having a relatively weak positive refractive power. 3 surface S13 and 4th surface S14 which has comparatively strong positive refractive power. The second prism 20 includes a fifth surface S21 having a relatively strong positive refractive power, a sixth surface S22 having a relatively weak positive refractive power, and a seventh surface S23 having a relatively strong positive refractive power. And an eighth surface S24 having a relatively strong negative refractive power. The specific specifications of the optical system of Example 1 will be described. The horizontal field angle is 20.1 °, the vertical field angle is 11.4 °, and the size of the display area of the video display element is 9.22 × 5. 18 mm, pupil diameter 5 mm, focal length about 26 mm.

  6A to 6F and FIGS. 7A to 7F show the aberrations of Example 1. FIG. In each aberration diagram, the horizontal axis indicates the position in the pupil, and the vertical axis indicates the amount of aberration. Specifically, FIGS. 6 (A) and 6 (B) show aberrations in the X and Y directions in micron units at an orientation of 10 ° in the X direction and 5.7 ° in the Y direction, and FIG. 6 (C). And 6 (D) show aberrations in the X and Y directions at an orientation of 0.0 ° in the X direction and 5.7 ° in the Y direction, and FIGS. 6 (E) and 6 (F) show − The aberrations in the X and Y directions are shown at an orientation of 5.7 ° in the Y direction at 10 °. 7 (A) and 7 (B) show the aberrations in the X and Y directions at an orientation of 10 ° in the X direction and 0.0 ° in the Y direction. FIGS. 7 (C) and 7 (D) 7 shows aberrations in the X and Y directions at an orientation of 0.0 ° in the direction and 0.0 ° in the Y direction, and FIGS. 7E and 7F show −10 ° in the X direction and 0. 0 in the Y direction. The aberrations in the X and Y directions at 0 ° azimuth are shown. The amount of aberration shown is the amount of aberration on the image plane of the image display element when the light beam is reversed for convenience.

(Example 2)
Table 4 below shows data of optical surfaces constituting the first and second prisms in the projection fluoroscopic apparatus of Example 2.
[Table 4]
No Type RT Nd Vd
1 SPH ∞ 20.00
2 FFS1 -72.491 5.30 1.525 55.95
3 FFS2 -52.343 -5.30 1.525 55.95
4 FFS1 -72.491 9.00 1.525 55.95
5 FFS3 -72.491 -8.00 1.525 55.95
6 FFS4 18.837 -2.00
7 FFS5 50.830 -19.00 1.525 55.95
8 FFS6 48.055 11.00 1.525 55.95
9 FFS7 -25.309 -13.00 1.525 55.95
10 FFS8 -7.981 -3.00
11 SPH ∞ -1.60 1.458 67.82
12 Image plane

Table 5 below shows the optical axis tilt angle (tilt) TLY and the optical axis shift amount (decenter) DCX in the cross section of the optical surface in the prism constituting the second embodiment.
[Table 5]
Face tilt and decenter
No Type TLY (front) DCX (back) TLY (back)
2 FFS1 0 0 0
3 FFS2 -27 0 27
4 FFS1 0 0 0
5 FFS3 0 19.294 -32.41
6 FFS4 0 0 0
7 FFS5 0 0 0
8 FFS6 23 0 23
9 FFS7 24 0 24
10 FFS8 0 0 0

Table 6 below shows coefficients obtained by polynomial expansion of a free-form surface for each optical surface in the prism constituting the second embodiment. In Table 6, symbols m and n mean variables or orders in the coefficient Akm _{, n} . The symbol FFSk (k = 1 to 8) means the k-th surface among the first to eighth surfaces S11 to S14 and S21 to S24 which are free-form surfaces.
[Table 6]
mn FFS1 FFS2 FFS3 FFS4
2 0 -4.253E-03 -9.662E-03 -4.253E-03 -2.219E-01
0 2 -6.897E-03 -9.552E-03 -6.897E-03 2.654E-02
3 0 -6.364E-06 -1.942E-05 -6.364E-06 -2.484E-02
1 2 2.116E-04 1.687E-04 2.116E-04 1.164E-03
4 0 -1.874E-06 -2.888E-06 -1.874E-06 -1.491E-03
2 2 6.279E-06 -2.247E-06 6.279E-06 1.417E-04
0 4 -1.403E-06 -4.500E-07 -1.403E-06 -9.344E-04

mn FFS5 FFS6 FFS7 FFS8
2 0 -2.619E-01 9.807E-03 -1.147E-02 1.912E-02
0 2 9.837E-03 1.040E-02 -1.976E-02 -6.265E-02
3 0 -2.355E-03 -1.162E-04 4.586E-05 -2.253E-03
1 2 -5.089E-03 -9.910E-05 6.582E-04 1.063E-03
4 0 4.022E-03 1.674E-05 2.477E-05 -4.367E-06
2 2 -1.214E-04 -3.752E-05 -4.655E-05 -5.860E-04
0 4 2.236E-03 -1.657E-05 1.447E-06 -4.977E-03

  FIG. 8 is a sectional view of the projection see-through device 70 of the second embodiment. The first prism 10 of the projection fluoroscopic device 70 includes a first surface S11 having a weak negative refractive power, a second surface S12 having a relatively strong positive refractive power, and a first surface having a relatively weak positive refractive power. 3 surface S13 and 4th surface S14 which has comparatively strong negative refractive power. The second prism 20 includes a fifth surface S21 having a relatively strong positive refractive power, a sixth surface S22 having a relatively weak positive refractive power, and a seventh surface S23 having a relatively weak positive refractive power. And an eighth surface S24 having a relatively weak positive refractive power. The specific specifications of the optical system of Example 2 will be described. The horizontal field angle is 20.1 °, the vertical field angle is 11.4 °, and the size of the display area of the video display element is 9.22 × 5. 18 mm, pupil diameter 5 mm, focal length about 26 mm.

  9 (A) to 9 (F) and FIGS. 10 (A) to 10 (F) show the aberrations of Example 2. FIG. Specifically, FIGS. 9A and 9B show aberrations in the X and Y directions at an orientation of 10 ° in the X direction and 5.7 ° in the Y direction, and FIGS. D) shows aberrations in the X and Y directions at an orientation of 0.0 ° in the X direction and 5.7 ° in the Y direction, and FIGS. 9 (E) and 9 (F) are −10 ° in the X direction. Aberrations in the X and Y directions at an orientation of 5.7 ° in the Y direction are shown. 10 (A) and 10 (B) show aberrations in the X and Y directions at an orientation of 10 ° in the X direction and 0.0 ° in the Y direction. FIGS. 10 (C) and 10 (D) 10A and 10F show aberrations in the X and Y directions at an orientation of 0.0 ° in the direction and 0.0 ° in the Y direction, and FIGS. 10E and 10F show −10 ° in the X direction and 0. 0 in the Y direction. The aberrations in the X and Y directions at 0 ° azimuth are shown.

(Example 3)
Table 7 below shows data of the optical surfaces constituting the first and second prisms of the projection fluoroscopic apparatus of Example 3.
[Table 7]
No Type RT Nd Vd
1 SPH ∞ 20.00
2 FFS1 -465.716 5.20 1.525 55.95
3 FFS2 -70.636 -5.20 1.525 55.95
4 FFS1 -465.716 9.00 1.525 55.95
5 FFS3 -465.716 -11.00 1.525 55.95
6 FFS4 -10.727 -2.00
7 FFS5 -15.211 -19.00 1.525 55.95
8 FFS6 53.194 21.00 1.525 55.95
9 FFS7 -28.725 -17.00 1.525 55.95
10 FFS8 -8.322 -3.00
11 SPH ∞ -1.60 1.458 67.82
12 Image plane

Table 8 below shows the optical axis tilt angle (tilt) TLY and the optical axis shift amount (decenter) DCX in the cross section of the optical surface in the prism constituting the third embodiment.
[Table 8]
No Type TLY (front) DCX (back) TLY (back)
2 FFS1 0 0 0
3 FFS2 -28 0 28
4 FFS1 0 0 0
5 FFS3 0 20.667 -48.12
6 FFS4 0 0 0
7 FFS5 0 0 0
8 FFS6 24 0 24
9 FFS7 20 0 20
10 FFS8 0 0 0

Table 9 below shows coefficients obtained by polynomial expansion of a free-form surface for each optical surface in the prism constituting the third embodiment. In Table 9, symbols m and n mean variables or orders in the coefficient Akm _{, n} . The symbol FFSk (k = 1 to 8) means the k-th surface among the first to eighth surfaces S11 to S14 and S21 to S24 which are free-form surfaces.
[Table 9]
mn FFS1 FFS2 FFS3 FFS4
2 0 -2.566E-03 -9.029E-03 -2.566E-03 5.809E-02
0 2 -1.074E-03 -7.079E-03 -1.074E-03 -4.661E-02
3 0 -2.231E-05 6.366E-06 -2.231E-05 3.317E-03
1 2 -2.822E-04 -2.354E-04 -2.822E-04 1.206E-02
4 0 7.767E-07 -1.640E-06 7.767E-07 -8.201E-04
2 2 -8.936E-06 -3.016E-06 -8.936E-06 -1.365E-03
0 4 -1.519E-06 -7.711E-06 -1.519E-06 -2.892E-04

mn FFS5 FFS6 FFS7 FFS8
2 0 -9.543E-02 7.508E-03 -1.130E-02 -1.163E-02
0 2 -3.287E-02 9.400E-03 -1.741E-02 -6.008E-02
3 0 2.698E-03 2.591E-05 2.707E-05 1.250E-03
1 2 -6.920E-03 1.397E-04 -9.938E-05 1.037E-02
4 0 1.158E-03 -4.820E-06 4.950E-06 9.670E-05
2 2 9.401E-04 -2.318E-05 6.743E-06 2.353E-03
0 4 -2.456E-03 -2.373E-05 4.273E-06 -1.620E-03

  FIG. 11 is a sectional view of the projection see-through device 70 of the third embodiment. The first prism 10 of the projection fluoroscopic device 70 includes a first surface S11 having a weak negative refractive power, a second surface S12 having a relatively strong positive refractive power, and a first surface having a relatively weak positive refractive power. 3 surface S13 and 4th surface S14 which has comparatively strong positive refractive power. The second prism 20 includes a fifth surface S21 having a relatively strong positive refractive power, a sixth surface S22 having a relatively weak positive refractive power, and a seventh surface S23 having a relatively weak positive refractive power. And an eighth surface S24 having a relatively weak negative refractive power. The specific specifications of the optical system of Example 3 will be described. The horizontal field angle is 20.1 °, the vertical field angle is 11.4 °, and the size of the display area of the video display element is 9.22 × 5. 18 mm, pupil diameter 5 mm, focal length about 26 mm.

  12 (A) to 12 (F) and FIGS. 13 (A) to 13 (F) show the aberrations of Example 3. FIG. Specifically, FIGS. 12A and 12B show aberrations in the X and Y directions at an orientation of 10 ° in the X direction and 5.7 ° in the Y direction, and FIGS. D) shows aberrations in the X and Y directions at an orientation of 0.0 ° in the X direction and 5.7 ° in the Y direction, and FIGS. 12 (E) and 12 (F) are −10 ° in the X direction. Aberrations in the X and Y directions at an orientation of 5.7 ° in the Y direction are shown. FIGS. 13A and 13B show aberrations in the X and Y directions at an orientation of 10 ° in the X direction and 0.0 ° in the Y direction. FIGS. 13C and 13D show the X and Y aberrations, respectively. The aberrations in the X and Y directions in the direction of 0.0 ° in the direction and 0.0 ° in the Y direction are shown. FIGS. 13 (E) and 12 (F) show −10 ° in the X direction and 0. 0 in the Y direction. The aberrations in the X and Y directions at 0 ° azimuth are shown.

Example 4
Table 10 below shows data on the optical surfaces constituting the first and second prisms of the projection fluoroscopic apparatus of Example 4.
[Table 10]
No Type RT Nd Vd
1 SPH ∞ 20.00
2 FFS1 -298.218 5.20 1.525 55.95
3 FFS2 -57.402 -5.20 1.525 55.95
4 FFS1 -298.218 9.00 1.525 55.95
5 FFS3 -298.218 -9.00 1.525 55.95
6 FFS4 -9.347 -2.00
7 FFS5 -13.667 -17.00 1.525 55.95
8 FFS6 41.835 18.00 1.525 55.95
9 FFS7 -25.971 -12.00 1.525 55.95
10 FFS8 -8.383 -3.00
11 SPH ∞ -1.60 1.458 67.82
12 Image plane

Table 11 below shows the optical axis tilt angle (tilt) TLY and the optical axis shift amount (decenter) DCX in the cross section of the optical surface in the prism constituting the fourth embodiment.
[Table 11]
No Type TLY (front) DCX (back) TLY (back)
2 FFS1 0 0 0
3 FFS2 -28 0 28
4 FFS1 0 0 0
5 FFS3 0 16.874 -51.1
6 FFS4 0 0 0
7 FFS5 0 0 0
8 FFS6 -26 0 -26
9 FFS7 22 0 22
10 FFS8 0 0 0

Table 12 below shows coefficients obtained by polynomial expansion of a free-form surface for each optical surface in the prism constituting the fourth embodiment. In Table 12, the symbols m and n mean variables or orders in the coefficient Akm _{, n} . The symbol FFSk (k = 1 to 8) means the k-th surface among the first to eighth surfaces S11 to S14 and S21 to S24 which are free-form surfaces.
[Table 12]
mn FFS1 FFS2 FFS3 FFS4
2 0 -2.644E-03 -9.209E-03 -2.644E-03 -1.852E-02
0 2 -1.677E-03 -8.710E-03 -1.677E-03 -5.349E-02
3 0 3.920E-06 -1.807E-05 3.920E-06 -5.324E-04
1 2 -2.192E-04 2.973E-05 -2.192E-04 -9.065E-03
4 0 3.150E-07 -2.251E-05 3.150E-07 2.407E-03
2 2 -5.820E-06 -1.361E-06 -5.820E-06 1.200E-03
0 4 -1.937E-05 -9.253E-06 -1.937E-05 -7.585E-04

mn FFS5 FFS6 FFS7 FFS8
2 0 -1.179E-01 8.088E-03 -1.254E-02 -3.407E-02
0 2 -3.658E-02 1.195E-02 -1.925E-02 -5.964E-02
3 0 7.169E-04 -1.035E-05 -2.363E-04 -3.925E-03
1 2 -8.876E-04 1.791E-04 1.218E-03 -9.235E-03
4 0 2.212E-03 -6.824E-07 1.407E-05 4.103E-04
2 2 1.131E-03 -2.936E-05 -9.347E-06 2.240E-03
0 4 -2.920E-04 -5.652E-06 1.454E-05 -3.056E-03

  FIG. 14 is a cross-sectional view of the projection see-through device 70 of the fourth embodiment. The first prism 10 of the projection fluoroscopic device 70 includes a first surface S11 having a weak negative refractive power, a second surface S12 having a relatively strong positive refractive power, and a first surface having a relatively weak positive refractive power. 3 surface S13 and 4th surface S14 which has comparatively weak negative refractive power. The second prism 20 includes a fifth surface S21 having a relatively strong positive refractive power, a sixth surface S22 having a relatively weak positive refractive power, and a seventh surface S23 having a relatively weak positive refractive power. And an eighth surface S24 having a relatively weak negative refractive power. The specific specifications of the optical system of Example 4 will be described. The horizontal field angle is 20.1 °, the vertical field angle is 11.4 °, and the size of the display area of the video display element is 9.22 × 5. 18 mm, pupil diameter 5 mm, focal length about 26 mm.

  15 (A) to 15 (F) and FIGS. 16 (A) to 16 (F) show the aberrations of Example 4. FIG. Specifically, FIGS. 15A and 15B show aberrations in the X and Y directions at an orientation of 10 ° in the X direction and 5.7 ° in the Y direction, and FIGS. D) shows aberrations in the X and Y directions at an orientation of 0.0 ° in the X direction and 5.7 ° in the Y direction, and FIGS. 15 (E) and 15 (F) show −10 ° in the X direction. Aberrations in the X and Y directions at an orientation of 5.7 ° in the Y direction are shown. 16 (A) and 16 (B) show aberrations in the X and Y directions at an orientation of 10 ° in the X direction and 0.0 ° in the Y direction. FIGS. 16 (C) and 16 (D) Aberrations in the X and Y directions in an orientation of 0.0 ° in the direction and 0.0 ° in the Y direction are shown. FIGS. 16 (E) and 16 (F) show −10 ° in the X direction and 0. 0 in the Y direction. The aberrations in the X and Y directions at 0 ° azimuth are shown.

Table 13 below summarizes numerical data related to conditional expressions (1) to (3) for each of Examples 1 to 4.

Table 14 below summarizes numerical data regarding the distance between the first surface S11 and the third surface S13 and the inclination angle of the second surface S12 with respect to the first surface S11 for each of Examples 1 to 4.

Conditional expression (3) affects the diopter of the prism with respect to external light, and the diopter Dx in the x-axis direction and the diopter Dy in the y-axis direction on the optical axis of the prism are the thickness of the prism. Is T and the refractive index is N,
Dx = 2000 (N−1) (A1 _2,0 −A3 _2,0 + (2T (N−1) / N) × A1 _2,0 × A3 _2,0 )
_{Dy = 2000 (N-1)} (A1 0,2 -A3 0,2 + (2T (N-1) / N) × A1 0,2 × A3 0,2)
Given in. Based on the above formula, the following Table 15 summarizes numerical data relating to the diopter for each of Examples 1 to 4.

[Others]
Although the present invention has been described with reference to each embodiment, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the spirit of the present invention. The following modifications are possible.

  In the above description, the half mirror layer (semi-transmissive reflective film) 15 is formed in a horizontally long rectangular region. However, the outline of the half mirror layer 15 can be changed as appropriate according to the purpose and other uses. Further, the transmittance and reflectance of the half mirror layer 15 can be changed according to the application and the like.

  In the above description, the display luminance distribution in the video display element 82 is not particularly adjusted. However, in the case where a luminance difference occurs depending on the position, the display luminance distribution can be adjusted unevenly.

  In the above description, the image display device 82 is a self-luminous display device, such as an organic EL or OLED, as the image display device 80. However, the image display device 80 is not limited to an organic EL and is an LED array. Can be used. Further, not only the video display element 82 formed of a self-luminous display device but also various ones can be used. For example, a configuration using a transmissive liquid crystal display device or a reflective liquid crystal display device is possible, and a digital micromirror device or the like can be used instead of the video display element 82 formed of a liquid crystal display device or the like.

  In the above embodiment, the image display device 80 including a self-luminous display device or the like is used, but a scanning image display device may be used instead.

  Specifically, as illustrated in FIG. 17, the first display device 100 </ b> A as a virtual image display device includes a light guide unit 330 corresponding to the projection fluoroscopic device 70 and an image display device 380. The image display device 380 is a device that forms intensity-modulated signal light and emits the signal light as scanning light TL, and includes a signal light forming unit 381 and a scanning optical system 382.

  The signal light forming unit 381 includes a light source, and emits signal light LL formed by modulation based on a control signal from a control circuit (not shown). The scanning optical system 382 emits the signal light LL that has passed through the signal light forming unit 381 while scanning. Here, the scanning optical system 382 is configured by a MEMS mirror or the like, and adjusts the optical path of the signal light LL by changing the posture in synchronization with the modulation of the signal light LL by the signal light forming unit 381. Two-dimensional scanning is performed to change the injection angle of (TL) vertically and horizontally. As described above, the image display device 380 causes the scanning light TL to be the video light GL to be incident on the light guide unit 330 and to scan the entire partial region of the second surface S12 where the half mirror layer 15 is formed. .

  The operation of the illustrated first display device 100A will be described. The image display device 380 emits the signal light LL as the scanning light TL toward the eighth surface S24 of the light guide 330 as described above. The light guide unit 330 guides the scanning light TL that has passed through the eighth surface S <b> 24 by total reflection or the like to reach the half mirror layer 15. At this time, by scanning the scanning light TL on the surface of the half mirror layer 15, a virtual image is formed by the image light GL as a locus of the scanning light TL, and the wearer grasps this virtual image with the eye EY. The image is recognized. In the illustrated case, the eighth surface S24 that is the light incident surface of the light guide 330 is a plane perpendicular to the optical axis of the scanning light TL.

  Further, as illustrated in FIG. 18, a correction lens CL may be further provided between the second prism 20 and the image display device 80. The correction lens CL is a lens having substantially no power, and can be used, for example, for suppressing aberrations.

  In the above-described embodiment, the first prism 10 serving as the light guide member and the light transmitting member 50 serving as the auxiliary prism are configured to cover the entire front of the wearer's eye EY. For example, as shown in FIGS. 19A and 19B, the portion including the second surface S12 having the curved surface shape having the half mirror layer 15 covers only a part of the eye EY. It is good also as a small structure which covers a part and also has the part which is not covered. Further, in this case, even if the first prism 10 and the light transmitting member 50 are made sufficiently small so that the see-through is not used and a mirror that performs total reflection instead of the half mirror layer 15 is disposed, The outside can be observed from the periphery of the prism 10 and the light transmitting member 50. In the illustrated case, the half mirror layer 15 is formed on the entire or substantially entire second surface S12. However, the half mirror layer 15 may be formed only on a part of the second surface S12. In the example of FIG. 19B, the half mirror layer 15 is disposed substantially in front of the eye EY. However, the image is obtained by moving the line of sight by shifting the half mirror layer 15 from the front. May be made visible. For example, the position of the eye EY may be slightly lowered (the positions of the first prism 10 and the light transmission member 50 are slightly raised). In this case, for example, the lower half of the eye EY can be seen from below the first prism 10 and the first light transmission member 50.

  In the above description, the virtual image display device 100 including the pair of display devices 100A and 100B is described. However, a single display device can be used. That is, the projection fluoroscopic device 70 and the image display device 80 are not provided for each of the right eye and the left eye, but only for either the right eye or the left eye. An image display device 80 may be provided so that the image is viewed with one eye.

  In the above description, the distance between the pair of display devices 100A and 100B in the X direction is not described, but the distance between the display devices 100A and 100B is not limited to being fixed, and the distance can be adjusted by a mechanical mechanism or the like. That is, the distance between both display devices 100A and 100B in the X direction can be adjusted according to the eye width of the wearer and the like.

  In the above description, the half mirror layer 15 is simply a semi-transmissive film (for example, a metal reflective film or a dielectric multilayer film). However, the half mirror layer 15 can be replaced with a planar or curved hologram element. .

  In the above description, the virtual image display device 100 has been specifically described as being a head-mounted display, but the virtual image display device 100 can be modified to a head-up display.

  In the above description, on the first surface S11 and the third surface S13 of the prism 10, the image light is totally reflected and guided by the interface with the air without applying a mirror or a half mirror on the surface. The total reflection in the virtual image display device 100 of the invention includes reflection that is formed by forming a mirror coat or a half mirror film on the whole or a part of the first surface S11 or the third surface S13. For example, after the incident angle of the image light satisfies the total reflection condition, the whole or a part of the first surface S11 or the third surface S13 is subjected to mirror coating or the like, and substantially all the image light is reflected. Cases are also included. In addition, as long as image light with sufficient brightness can be obtained, the first surface S11 or the third surface S13 may be entirely or partially coated with a somewhat transmissive mirror.

  In the above description, the prism 10 and the like extend in the horizontal direction in which the eyes EY are arranged, but the prism 10 may be arranged to extend in the vertical direction. In this case, the optical member 110 has a structure arranged in parallel, not in series.

  AX1-AX4 ... Optical axis, AXI ... Incident side optical axis, AXO ... Emission side optical axis, EY ... Eye, GL ... Video light, HL ... External light, II ... Image plane of intermediate image, PA ... Partial area, S11- S14-1st-4th surface, S21-S24-5th-8th surface, S51-S53-1st-3rd transmission surface, SL-illumination light, SR-reference plane, 10-1st prism, 20- 2nd prism, 10s, 20s ... main body part, 15 ... half mirror layer, 50 ... light transmission member, 70 ... projection see-through device, 80 ... image display device, 82 ... video display element (video element), 84 ... drive control part 100 ... Virtual image display device, 100A, 100B ... Display device, 103a, 103b ... Optical part, 101 ... Transparent member, 102 ... Frame, 15 ... Mirror surface, CC ... Adhesive

Claims (12)

A virtual image table display device for simultaneously visualizing image light and external light,
An image element for generating image light;
A first prism including two or more non-axisymmetric curved surfaces;
A second prism including two or more non-axisymmetric curved surfaces,
The optical system including at least the second prism is a relay optical system that forms an intermediate image on an optical path from the first prism to the second prism,
When the outside is visually recognized through the first surface and the third surface among the plurality of surfaces constituting the first prism, the diopter is substantially 0,
The first surface and the third surface have a concave shape with respect to the observation side,
The image light from the image element is totally reflected by the third surface, totally reflected by the first surface, reflected by the second surface, and then passes through the first surface to reach the observation side. Virtual image display device. A polynomial term x representing the k-th surface when a surface shape expression is polynomial-expanded with respect to orthogonal coordinates x and y extending in the tangential direction from the origin with reference to the origin of each surface constituting the optical system. ^2. The virtual image display device according to claim 1, wherein the following conditions (1) to (3) are satisfied _{, where} ^m · y ^{n is} a coefficient of Ak _{m, n} .
−5 × 10 ⁻² <A1 _2,0 + A1 _0,2 <−1 × 10 ⁻³ and −5 × 10 ⁻² <A3 _2,0 + A3 _0,2 <−1 × 10 ⁻³ (1)
| A3 _2,0 −A3 _0,2 | <1 × 10 ⁻² (2)
| A1 _2,0 −A3 _2,0 | <5 × 10 ⁻³ and | A1 _0,2 −A3 _0,2 | <5 × 10 ⁻³ (3)   The virtual image display device according to claim 1, wherein the first prism and the second prism having a plurality of surfaces are formed separately.   A half mirror is formed on the second surface to present image light to an observer, and a light transmitting member is integrally disposed on the outside of the second surface so that the diopter for external light is substantially zero, The virtual image display device according to any one of claims 1 and 2, wherein light and video light are superimposed and presented to an observer.   The light transmission member has a first transmission surface and a second transmission surface on the observer side and a third transmission surface on the outside, and the second surface of the first prism and the second surface of the light transmission member. The virtual image display device according to claim 4, wherein the transmission surface has substantially the same curved surface shape, and the second surface and the second transmission surface are integrated.   The virtual image display according to any one of claims 1 to 3, wherein the first surface, the second surface, and the third surface have a symmetrical shape with a reference surface including an optical path passing through the first surface, the second surface, and the third surface interposed therebetween. apparatus.   The virtual image display device according to any one of claims 1 to 6, wherein an interval between the first surface and the third surface is 5 mm or more and 15 mm or less.   The virtual image display device according to any one of claims 1 to 7, wherein an inclination angle of the second surface with respect to the first surface is 20 ° or greater and 40 ° or less.   The virtual image display device according to any one of claims 1 to 8, wherein the video element is fixed integrally to the second prism so as to face an image light incident surface of the second prism. .   The second prism has a plurality of surfaces, and an intermediate image is formed by the image element, the plurality of surfaces of the second prism, and a fourth surface which is a light incident surface of the first prism. 10. The virtual image display device according to any one of items 9 to 9.   The virtual image according to any one of claims 1 to 10, wherein the optical system including the first prism covers a part of the front of the observer's eyes and a part that is not covered by the eyes at the time of wearing. Display device.   The video device includes a signal light forming unit that emits signal light modulated in accordance with an image, and a scanning optical system that emits scanning light by scanning the signal light incident from the signal light forming unit. The virtual image display device according to any one of claims 1 to 11, further comprising:

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