JP2013037260A - Virtual image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a virtual image display device that suppresses an occurrence of luminance unevenness and enhances utilization efficiency of illuminating light.SOLUTION: In a virtual image display device of one embodiment, an optical directivity changing section forms a non-uniform distribution with respect to directivity of image light GL emitted from an image display device. Accordingly, even when angles of light beams emitted from the image display device and effectively taken into eyes EY of an observer are greatly different from one another depending upon a position of the image display device, the image light GL that has the directivity in response to angular characteristics of such taking-in of the light beams can be formed, an occurrence of luminance unevenness can be suppressed and utilization efficiency of illuminating light can be enhanced.

Description

  The present invention relates to a virtual image display device such as a head mounted display that is used by being mounted on a head.

  2. Description of the Related Art In recent years, various types of virtual image display devices that enable formation and observation of virtual images, such as a head-mounted display, have been proposed that guide video light from a display element to an observer's pupil using a light guide plate. As a light guide plate for such a virtual image display device, a plurality of partial reflection surfaces arranged to be parallel to each other at a predetermined angle with respect to the main surface of the light guide plate while guiding image light using total reflection. It is known that image light is reflected and taken out of the light guide plate to reach the observer's retina (see Patent Documents 1 and 2).

  In the virtual image display device as described above, for example, the light beams from the upper and lower ends of the vertical cross section of the display element must be incident on the observer's pupil at a large inclination angle corresponding to the angle of view. It will be emitted at a large inclination angle. Since the light beam from the center of the display element is incident on the observer's pupil without being tilted from the front, it is also emitted from the display element in the front direction. In the above, when the display element is a combination of a lighting device and a liquid crystal panel, for example, the light distribution of the lighting device is generally uniform in the screen with the intensity peak in the direction perpendicular to the liquid crystal panel. Even if the luminance is high in the center portion of the image where the light inclination is small, the luminance is lowered at the upper and lower ends of the image where the inclination of the illumination light is large, which causes luminance unevenness of the image. In this case, illumination light is not effectively utilized at the upper and lower ends of the screen, and it can be said that the utilization efficiency of illumination light is reduced.

  On the other hand, regarding the luminous flux from the cross section of the display element, the angle direction taken into the light guide plate and used for display is largely inclined from the front direction of the display element, depending on the lateral position. For this reason, even when the luminance is high at a specific lateral position where the inclination of the illumination light is small, a phenomenon may occur in which the luminance decreases at another horizontal position where the inclination of the illumination light is large. In this case, the illumination light is not efficiently used, and strip-like luminance spots extending in the vertical direction are generated.

Special table 2003-536102 gazette JP 2004-157520 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a virtual image display device that suppresses the occurrence of luminance spots and increases the use efficiency of illumination light.

  In order to achieve the above object, a virtual image display device according to the present invention includes (a) an image display device that forms image light, and (b) a projection optical system that forms a virtual image by image light emitted from the image display device. (C) A light incident part that takes in the image light that has passed through the projection optical system, and a light guide that guides the image light taken from the light incident part by total reflection at the first and second reflection surfaces that extend opposite to each other. A light guide device having a light emitting unit for taking out image light that has passed through the light guide unit to the outside, and (d) nonuniformity by changing the directivity of the image light emitted from the image display device And an optical directivity changing unit that forms a uniform distribution. Here, the directivity of the image light means that the luminance center of the image light emitted from the image display device is biased in a specific direction (specifically, a specific tilt angle and azimuth angle).

  In the virtual image display device, since the optical directivity changing unit forms a non-uniform distribution with respect to the directivity of the image light emitted from the image display device, it is emitted from the image display device depending on the position of the image display device. Even when the angle of the light flux that is effectively captured by the eyes is greatly different, it is possible to form image light having directivity that corresponds to the angle characteristics of such light flux capture, and to generate luminance spots. It is possible to increase the use efficiency of illumination light by suppressing the above. Note that the above-described angular characteristics of the light beam capture are generated depending on the specifications of the projection optical system and the light guide device, and for example, the inclination is larger on the peripheral side than on the center side of the display area of the image display device. Or tends to be larger on the center side than on the peripheral side of the display area.

  In a specific aspect of the present invention, in the virtual image display device, the optical directivity changing unit bends light at different angles with respect to the first direction depending on the position of the image display device. In this case, the angle characteristic can be adjusted by bending the illumination light or the image light according to the position in the first direction, and the angle characteristic of the light flux capturing is locally increased in the cross section in the first direction. Even if it is a thing, it can suppress a brightness spot and can improve light utilization efficiency.

  In another aspect of the present invention, the optical directivity changing unit bends light at a different angle depending on the position of the image display device with respect to the second direction perpendicular to the first direction. In this case, the angle characteristic can be adjusted by bending the illumination light or the image light according to the position in the second direction, and the angle characteristic of the light flux capturing locally increases in the cross section in the second direction. Even if it is a thing, it can suppress a brightness spot and can improve light utilization efficiency.

  In still another aspect of the present invention, the optical directivity changing unit has different light distribution characteristics which are angular distributions of directivity with respect to the first direction and the second direction. Due to the structure of the light guide, etc., the angular characteristics of the light flux capture may be different between the first direction and the second direction (for example, the vertical direction and the horizontal direction). Can be suppressed.

  In still another aspect of the present invention, an image display device includes an illumination device and an image light forming unit that controls the light from the illumination device to form image light.

  In yet another aspect of the present invention, the illumination device includes a light emitting unit and a backlight light guide unit that spreads a light beam from the light emitting unit in a surface light source shape, and the optical directivity changing unit is a backlight light guide unit. And the image light forming unit. In this case, even if the light distribution characteristic of the illumination light emitted from the light exit surface of the backlight light guide unit is uniform, the light distribution characteristic of the illumination light incident on the image light forming unit by the optical directivity changing unit Can be adjusted to a desired state, and the directivity of the image light emitted from the image display device can be made to correspond to the angle characteristic of the above-mentioned luminous flux capture.

  In yet another aspect of the present invention, the lighting device includes a surface light source-like light emitting unit, and the optical directivity changing unit is disposed between the surface light source-like light emitting unit and the image light forming unit. In this case, even if the light distribution characteristic of the illumination light emitted from the surface light source-like light emitting unit is uniform, the light distribution characteristic of the illumination light incident on the image light forming unit by the optical directivity changing unit is in a desired state. The directivity of the image light emitted from the image display device can be adjusted to correspond to the angle characteristic of the light flux taking-in.

  In still another aspect of the present invention, the optical directivity changing unit is at least one of a prism array sheet, a Fresnel lens, a diffractive optical element, and a microlens array.

  In still another aspect of the present invention, the optical directivity changing unit is attached to the backlight light guide unit or the surface light source-like light emitting unit and integrated with the backlight light guide unit. In this case, the optical directivity changing unit can be easily assembled in the image display device.

  In yet another aspect of the present invention, the optical directivity changing unit passes illumination light from the backlight light guide unit or the surface light source light emitting unit so that the main directivity directions having the highest luminance are different from each other. A plurality of region portions to be made. In this case, the light distribution characteristic of the illumination light can be in an appropriate state for each of the plurality of region portions.

  In still another aspect of the present invention, the optical directivity changing unit has a prism array having a different shape corresponding to a plurality of region portions. In this case, the light distribution characteristic of the illumination light can be adjusted to the target by adjusting the wedge angle of the prism elements constituting the prism array in each region.

  In still another aspect of the present invention, the first direction corresponds to a folding direction perpendicular to the first and second reflection surfaces of the light guide device, and the second direction corresponds to the first and second reflection surfaces of the light guide device. A plurality of peak directions corresponding to the non-folding direction that is parallel to the first direction and perpendicular to the first direction and at which the luminance is maximized are set in at least one of the first direction and the second direction.

  In still another aspect of the present invention, a plurality of peak directions in which the luminance is maximized are set in the second direction. Regarding the second direction corresponding to the non-folding direction of the light guide device, it is not a uniform tendency that the inclination angle of the image light captured on the peripheral side is larger than the center side of the display region of the image display device, The inclination angle of the image light captured at each position in the second direction changes non-uniformly. Therefore, brightness spots can be reduced by adjusting the directivity of the image light with respect to the second direction.

  In still another aspect of the present invention, the optical directivity changing section is built in or externally attached to the image light forming section.

  In still another aspect of the present invention, the image light forming section is an EL display element, and the optical directivity changing section is disposed, for example, close to the light emission side of the pixel portion of the EL display element.

  In still another aspect of the present invention, the image light forming unit is a light transmissive liquid crystal display element, and the optical directivity changing unit is provided on at least one of the light incident side and the light emitting side of the pixel portion of the liquid crystal display element. For example, they are arranged close to each other. In this case, even if the light distribution characteristic of the illumination light emitted from the light exit surface of the backlight light guide unit is uniform, the direction of the illumination light incident on the image light forming unit by the optical directivity changing unit, The direction of the image light emitted from the image light forming unit can be adjusted. That is, the directivity of the image light emitted from the image display device can be made to correspond to the angle characteristic of the light flux capturing.

  In still another aspect of the present invention, the light guide unit has a first reflection surface and a second reflection surface that are arranged in parallel to each other and enable light guide by total reflection, and the light incident unit is the first reflection surface. A third reflective surface having a predetermined angle with respect to the surface is provided, and the light emitting portion has a fourth reflective surface having a predetermined angle with respect to the first reflective surface. In this case, the image light reflected by the third reflecting surface of the light incident portion is propagated while being totally reflected by the first and second reflecting surfaces of the light guide portion, and is reflected by the fourth reflecting surface of the light emitting portion to be a virtual image. As incident on the eyes of the observer.

  In yet another aspect of the present invention, the light emitting unit includes a plurality of reflection surfaces and an angle conversion unit that converts the angle of the image light by reflection on the plurality of reflection surfaces and can be extracted to the outside. In this case, the light beam from the thin light guide can be divided and extracted in an appropriate direction.

  In still another aspect of the present invention, the angle conversion unit has a first reflection surface and a second reflection surface that forms a predetermined angle with respect to the first reflection surface, and is arranged in a predetermined arrangement direction. A plurality of reflecting units, each reflecting unit reflecting the image light incident through the light guide unit by the first reflecting surface and the image light reflected by the first reflecting surface by the second reflecting surface; Further, by reflecting, the optical path of the image light can be bent and taken out to the outside. In this case, image light with a large reflection angle propagating through the light guide unit can be taken out at the back side of the angle conversion unit, and image light with a small reflection angle propagating through the light guide unit can be taken out at the entrance side of the angle conversion unit. In addition, it is possible to display a high-quality image that reliably suppresses luminance reduction and luminance unevenness due to the angle conversion unit.

It is a perspective view which shows the virtual image display apparatus of 1st Embodiment. (A) is a top 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. (A) is the conceptual diagram which expand | deployed the optical path regarding the vertical 1st direction, (B) is the conceptual diagram which expand | deployed the optical path regarding the horizontal 2nd direction. It is a top view explaining the optical path in the optical system of a virtual image display apparatus concretely. (A) shows the display surface of a liquid crystal display device, (B) is a figure explaining notionally the virtual image of the liquid crystal display device which an observer can see, (C) and (D) comprise a virtual image It is a figure explaining the partial image to do. (A) is a side view for explaining the emission angle in the vertical direction of image light emitted from the liquid crystal display device, and (B) is a graph for conceptually explaining the angle characteristics of light flux taking in in the vertical direction. . (A) is a side view for explaining the emission angle in the horizontal direction of image light emitted from the liquid crystal display device, and (B) is a graph for conceptually explaining the angle characteristics of light flux taking in in the horizontal direction. . It is a conceptual diagram explaining the angle characteristic of light beam taking-in as a two-dimensional distribution. FIGS. 3A to 3D are a plan view, a side view, a rear view, and a partially broken perspective view illustrating an optical directivity changing unit for adjusting directivity of image light. (A) shows the light distribution characteristic on the entrance side of the optical directivity change unit, (B) shows the vertical light distribution characteristic on the exit side of the optical directivity change unit, and (C) shows the optical directivity. The light distribution characteristic of the horizontal direction in the exit side of a property change part is shown. It is an enlarged vertical sectional view explaining the structure and function of an optical directivity change part. It is an expanded horizontal sectional view explaining the structure and function of an optical directivity change part. (A) And (B) is the longitudinal cross-section and cross-sectional view explaining the liquid crystal display device etc. which are integrated in the virtual image display apparatus concerning 2nd Embodiment. (A) And (B) is a figure explaining the modification of 2nd Embodiment. (A) And (B) is the longitudinal cross-section and cross-sectional view explaining the liquid crystal display device etc. which are integrated in the virtual image display apparatus concerning 3rd Embodiment. (A) And (B) is a figure explaining the modification of 2nd Embodiment. It is a figure explaining the principal part of the virtual image display apparatus of 4th Embodiment. It is a partially expanded sectional view explaining the virtual image display apparatus which concerns on 5th Embodiment. (A) And (B) is a figure explaining the virtual image display apparatus which concerns on 6th Embodiment. (A) is sectional drawing which shows the virtual image display apparatus which concerns on 7th Embodiment, (B) and (C) are the front views and top views of a light guide device. (A)-(C) are typical figures for demonstrating the structure of an angle conversion part, and the optical path of the image light in an angle conversion part. (A), (B) is a figure explaining a part of virtual image display apparatus of 8th Embodiment. It is a figure explaining the virtual image display apparatus of 9th Embodiment. It is a figure which illustrates one modification of a virtual image display apparatus notionally.

[First Embodiment]
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)
The virtual image display device 100 according to the first 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 recognize image light due to a virtual image. In addition, it is possible to make the observer observe the outside world image with see-through. The virtual image display device 100 includes an optical panel 110 that covers the viewer's eyes, a frame 121 that supports the optical panel 110, and first and second drive units 131 and 132 that are added to a portion of the frame 121 from the end to the temple. With. Here, the optical panel 110 has a first panel portion 111 and a second panel portion 112, and both the panel portions 111 and 112 are plate-like parts integrally connected at the center. The first display device 100A in which the first panel portion 111 on the left side and the first drive unit 131 are combined in the drawing is a portion that forms a virtual image for the left eye, and functions alone as a virtual image display device. Further, the second display device 100B in which the second panel portion 112 on the right side and the second driving unit 132 in the drawing are combined is a portion that forms a virtual image for the right eye, and functions alone as a virtual image display device. The first drive unit 131 and the second drive unit 132 are individually housed in a light shielding and protection case 141.

[B. Display device structure]
As shown in FIG. 2A and the like, the first display device 100A includes an image forming device 10 and a light guide device 20. Here, the image forming apparatus 10 corresponds to the first driving unit 131 in FIG. 1, and the light guide device 20 corresponds to the first panel portion 111 in FIG. As for the image forming apparatus 10, a main body portion excluding the case 141 in FIG. 1 is illustrated. 2A, a portion of the light guide device 20 is a cross-sectional view taken along arrow AA 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.

  The image forming apparatus 10 includes an image display device 11, a projection optical system 12, and an optical directivity changing unit 38. Among these, the image display device 11 includes an illumination device 31 that emits two-dimensional illumination light SL, a liquid crystal display device (liquid crystal display element) 32 that is a transmissive image light forming unit, and the illumination device 31 and the liquid crystal display. And a drive control unit 34 that controls the operation of the device 32.

  The illuminating device 31 includes a light source 31a that is a light emitting unit that generates light including three colors of red, green, and blue, and a back light that diffuses light from the light source 31a and has a two-dimensional spread of a rectangular cross section. And a light guide 31b. The liquid crystal display device (image light forming unit) 32 spatially modulates the illumination light SL from the illumination device 31 to form image light to be a display target such as a moving image. The drive control unit 34 includes a light source drive circuit 34a and a liquid crystal drive circuit 34b. The light source driving circuit 34a supplies electric power to the light source (light emitting unit) 31a of the illumination device 31 to emit illumination light SL having a stable luminance. The liquid crystal driving circuit 34b outputs an image signal or a driving signal to the liquid crystal display device (image light forming unit) 32, thereby forming color image light as a source of a moving image or a still image as a transmittance pattern. The liquid crystal driving circuit 34b can have an image processing function, but an external control circuit can also have an image processing function.

  The optical directivity changing unit 38 is disposed between the lighting device 31 and the liquid crystal display device 32, and considers utilization efficiency with respect to the angular distribution or light distribution characteristic of the directivity of the illumination light emitted from the lighting device 31. It is a deflection | deviation element for correcting to the appropriate thing. The optical directivity changing unit (deflection element) 38 sets the directivity of the image light emitted from the liquid crystal display device 32 so that the image light emitted from the liquid crystal display device 32 is incident on the eye EY of the observer as a result. It is adjusted so as to correspond to an effective range of effective emission angles (angle characteristics of light beam capture described later).

  In the liquid crystal display device 32, the first direction D1 is a direction in which a longitudinal section including a first optical axis AX1 passing through the projection optical system 12 and a specific line parallel to a third reflecting surface 21c of the light guide member 21 described later extends. The second direction D2 corresponds to a direction in which a transverse section including the first optical axis AX1 and the normal line of the third reflecting surface 21c extends. In other words, the first direction D1 is a direction parallel to the intersecting line of the first reflecting surface 21a and the third reflecting surface 21c of the light guide member 21 described later, and the second direction D2 is the first reflecting surface 21a. Is parallel to the plane and is perpendicular to the line of intersection of the first reflecting surface 21a and the third reflecting surface 21c. That is, at the position of the liquid crystal display device 32, the first direction D1 corresponds to the vertical Y direction, and the second direction D2 corresponds to the horizontal X direction. Here, the effective size H in the vertical first direction D1 of the liquid crystal display device 32 is smaller than the effective size W in the horizontal second direction D2 of the liquid crystal display device 32 (see FIG. 2B and the like). . That is, the image forming area AD of the liquid crystal display device 32 is horizontally long. The first direction D1 is parallel to the Y direction in both the image forming apparatus 10 and the light guide member 21 described later, and corresponds to the non-folding direction or the non-confining direction DW2 of the latter light guide member 21. It has become. The second direction D2 is parallel to the X direction in the image forming apparatus 10, but is parallel to the Z direction in the light guide member 21 described later, and corresponds to the folding direction or the confinement direction DW1. Yes.

  The projection optical system 12 is a collimating lens that converts image light emitted from each point on the liquid crystal display device 32 into light beams in a parallel state. The projection optical system 12 includes, for example, lens groups L1 to L3, and a lens barrel 12a that supports the lens groups L1 to L3 from the periphery is housed in the case 141 of FIG. The optical surfaces of the lenses constituting each of the lens groups L1 to L3 have a spherical or aspherical shape that is rotationally symmetric about the first optical axis AX1, and the condensing characteristics in the first direction D1 and the second direction. It is equal to the condensing characteristic of D2. The optical surface 12f of the lens unit L3 is exposed at the exit opening EA on the most light exit side of the lens barrel 12a that houses the lens units L1 to L3. Here, the injection opening width E1 of the injection opening EA in the first direction D1 is larger than the injection opening width E2 of the injection opening EA in the second direction D2 (see FIG. 2B). This is due to the difference between the vertical and horizontal optical paths, which will be described in detail later. In the first vertical direction D1, that is, the Y direction, the image light GL needs to be incident on the light guide device 20 as a relatively wide light beam width. This is because the second horizontal direction D2 needs to be incident on the light guide device 20 with a relatively narrow luminous flux width.

  The light guide device 20 is formed by joining a light guide member 21 and a light transmission member 23, and constitutes a flat plate-like optical member that extends parallel to the XY plane as a whole.

  In the light guide device 20, the light guide member 21 is a trapezoidal prism-like member in plan view, and includes, as side surfaces, a first reflection surface 21 a, a second reflection surface 21 b, a third reflection surface 21 c, and a fourth reflection surface. A reflective surface 21d. The light guide member 21 includes an upper surface 21e and a lower surface 21f that are adjacent to the first, second, third, and fourth reflecting surfaces 21a, 21b, 21c, and 21d and that face each other. Here, the first and second reflecting surfaces 21 a and 21 b extend along the XY plane and are separated by the thickness t of the light guide member 21. The third reflecting surface 21c is inclined at an acute angle α of 45 ° or less with respect to the XY plane, and the fourth reflecting surface 21d is inclined at an acute angle β of 45 ° or less with respect to the XY surface, for example. . The first optical axis AX1 passing through the third reflecting surface 21c and the second optical axis AX2 passing through the fourth reflecting surface 21d are arranged in parallel and separated by a distance D. An end surface 21h is provided between the first reflecting surface 21a and the third reflecting surface 21c so as to remove a ridge. Further, an end surface 21i is provided between the first reflecting surface 21a and the fourth reflecting surface 21d so as to remove a ridge. The light guide member 21 has an outer shape of an eight-sided polyhedron including these end faces 21h and 21i.

  The light guide member 21 performs light guide using total reflection by the first and second reflection surfaces 21a and 21b, and is a direction that is folded by reflection when light is guided and a direction that is not folded by reflection when light is guided. There is. When an image guided by the light guide member 21 is considered, a lateral direction that propagates while being folded back by a plurality of reflections during light guide, that is, a confinement direction DW2 is perpendicular to the first and second reflecting surfaces 21a and 21b (Z When the optical path is extended to the light source side in parallel with the axis, it corresponds to the second direction D2 of the liquid crystal display device 32. On the other hand, the longitudinal direction, that is, the non-confining direction DW1 that propagates without being folded back by reflection during light guide is parallel to the first and second reflecting surfaces 21a, 21b and the third reflecting surface 21c (parallel to the Y axis), which will be described later. Thus, when the optical path is developed to the light source side, it corresponds to the first direction D1 of the liquid crystal display device 32. In the light guide member 21, the main light direction in which the propagated light beam travels as a whole is parallel to the −X direction.

  The light guide member 21 is formed of a resin material that exhibits high light transmittance in the visible range. The light guide member 21 is a block-like member that is integrally molded by injection molding, and is formed by, for example, injecting a heat or photopolymerization type resin material into a molding die and curing or curing it. . Thus, although the light guide member 21 is an integrally formed product, it can be functionally divided into the light incident part B1, the light guide part B2, and the light emitting part B3.

  The light incident part B1 is a triangular prism-shaped part, and includes a light incident surface IS that is a part of the first reflective surface 21a and a third reflective surface 21c that faces the light incident surface IS. The light incident surface IS is a flat surface on the back side or the viewer side for taking in the image light GL from the image forming apparatus 10 and extends perpendicularly to the first optical axis AX1 facing the projection optical system 12. The third reflecting surface 21c has a rectangular outline, and has a total reflection mirror layer 25 for reflecting the image light GL that has passed through the light incident surface IS and guiding it into the light guide B2 over the entire rectangular area. . The total reflection mirror layer 25 is formed by forming a film on the slope RS of the light guide member 21 by vapor deposition of aluminum or the like. The third reflecting surface 21c is inclined with respect to the first optical axis AX1 or the XY plane of the projection optical system 12, for example, at an acute angle α = 25 ° to 27 °, and is incident from the light incident surface IS in the + Z direction as a whole. The image light GL that is directed is bent so as to be directed in the −X direction that is closer to the −Z direction as a whole, so that the image light GL is reliably coupled into the light guide portion B2.

  The light guide B2 has first and second reflecting surfaces 21a and 21b that totally reflect the image light bent by the light incident portion B1 as two planes that face each other and extend parallel to the XY plane. Yes. The distance between the first and second reflecting surfaces 21a and 21b, that is, the thickness t of the light guide member 21 is, for example, about 9 mm. Here, it is assumed that the first reflecting surface 21a is on the back side or the viewer side close to the image forming apparatus 10, and the second reflecting surface 21b is on the front side or the outside side far from the image forming apparatus 10. In this case, the first reflecting surface 21a is a surface portion common to the above-described light incident surface IS and a light emitting surface OS described later. The first and second reflection surfaces 21a and 21b are total reflection surfaces using a difference in refractive index, and the surface thereof is not provided with a reflective coating such as a mirror layer, but the surface is prevented from being damaged and the image is displayed. In order to prevent a reduction in resolution, a hard coat layer is coated. The hard coat layer is formed by depositing a coating material containing a resin or the like on the light guide member 21 by dipping or spray coating.

  The image light GL reflected by the third reflecting surface 21c of the light incident part B1 first enters the first reflecting surface 21a and is totally reflected. Next, the image light GL enters the second reflecting surface 21b and is totally reflected. Thereafter, by repeating this operation, the image light is guided to the leading light direction on the back side of the light guide device 20 as a whole, that is, to the −X side provided with the light emitting part B3. In addition, since the 1st and 2nd reflective surfaces 21a and 21b are not provided with the reflective coating, the external light or the external light incident on the second reflective surface 21b from the external side passes through the light guide B2 with high transmittance. pass. In other words, the light guide B2 is a see-through type that allows the external image to be seen through.

  The light emission part B3 is a triangular prism-shaped part, and has a light emission surface OS that is a part of the first reflection surface 21a and a fourth reflection surface 21d that faces the light emission surface OS. The light exit surface OS is a flat surface on the back side for emitting the image light GL toward the observer's eye EY. The light exit surface OS is a part of the first reflecting surface 21a like the light incident surface IS. It extends perpendicular to the optical axis AX2. The distance D between the second optical axis AX2 passing through the light emitting part B3 and the first optical axis AX1 passing through the light incident part B1 is set to, for example, 50 mm in consideration of the width of the observer's head. The fourth reflecting surface 21d is a substantially rectangular flat surface for reflecting the image light GL that has entered through the first and second reflecting surfaces 21a and 21b to be emitted outside the light emitting portion B3. A half mirror layer 28 is attached to the fourth reflecting surface 21d. The half mirror layer 28 is a light-transmissive reflective film (that is, a semi-transmissive reflective film). The half mirror layer (semi-transmissive reflective film) 28 is formed by forming a metal reflective film or a dielectric multilayer film on the slope RS of the light guide member 21. The reflectance of the half mirror layer 28 with respect to the image light GL is set to 10% to 50% in the assumed incident angle range of the image light GL from the viewpoint of facilitating observation of the external light GL ′ by see-through. The reflectance of the half mirror layer 28 of the specific embodiment with respect to the image light GL is set to 20%, for example, and the transmittance with respect to the image light GL is set to 80%, for example.

  The fourth reflecting surface 21d is inclined with respect to the second optical axis AX2 or XY plane perpendicular to the first reflecting surface 21a, for example, at an acute angle α = 25 ° to 27 °, and is guided by the half mirror layer 28. The image light GL incident through the first and second reflecting surfaces 21a and 21b of the portion B2 is partially reflected and bent so as to be directed in the −Z direction as a whole, thereby allowing the light exit surface OS to pass therethrough. Note that the image light GL transmitted through the fourth reflecting surface 21d is incident on the light transmitting member 23 and is not used to form an image.

  The light transmission member 23 has the same refractive index as that of the main body of the light guide member 21, and includes a first surface 23a, a second surface 23b, and a third surface 23c. The first and second surfaces 23a and 23b extend along the XY plane. The third surface 23 c is inclined with respect to the XY plane, and is disposed in parallel to face the fourth reflecting surface 21 d of the light guide member 21. That is, the light transmission member 23 is a member having a wedge-shaped portion 23v sandwiched between the second surface 23b and the third surface 23c. Similar to the light guide member 21, the light transmissive member 23 is formed of a resin material exhibiting high light transmittance in the visible region. The light transmitting member 23 is a block-like member that is integrally molded by injection molding, and is formed, for example, by injecting a thermopolymerization resin material into a molding die and thermosetting it.

  In the light transmission member 23, the first surface 23 a is disposed on the extended plane of the first reflecting surface 21 a provided on the light guide member 21, is on the back side close to the observer's eye EY, and the second surface 23 b is guided. It is arranged on the extended plane of the second reflecting surface 21b provided on the optical member 21, and is on the front side far from the observer's eye EY. The third surface 23c is a rectangular transmission surface joined to the fourth reflection surface 21d of the light guide member 21 by an adhesive. The angle formed by the first surface 23a and the third surface 23c is equal to the angle ε formed by the second reflective surface 21b and the fourth reflective surface 21d of the light guide member 21, and the second surface 23b and the third surface 23c are the same. The angle formed with the surface 23 c is equal to the angle β formed between the first reflecting surface 21 a and the third reflecting surface 21 c of the light guide member 21.

  The light transmission member 23 and the light guide member 21 constitute a see-through portion B4 at a joint portion between the light transmission member 23 and the vicinity thereof in a portion facing the eyes of the observer. Of the light transmitting member 23, the wedge-shaped portion 23v that is sandwiched between the second surface 23b and the third surface 23c that form an acute angle and expands in the −X direction is similarly joined to the wedge-shaped light emitting portion B3. The central portion in the X direction of the flat see-through portion B4 as a whole is configured. Since the first and second surfaces 23a and 23b are not provided with a reflective coating such as a mirror layer, the external light GL ′ is transmitted with a high transmittance similarly to the light guide portion B2 of the light guide member 21. The third surface 23c can also transmit the external light GL ′ with high transmittance, but since the fourth reflecting surface 21d of the light guide member 21 has the half mirror layer 28, the third surface 23c passes through the third surface 23c. The ambient light GL ′ to be attenuated by, for example, 20% in the half mirror layer 28. That is, the observer observes the image light GL that has been reduced to 20% and the external light GL ′ that has been reduced to 80% through the half mirror layer 28.

[C. Overview of optical path of image light)
FIG. 3A is a diagram illustrating an optical path in the first direction D1 corresponding to the longitudinal section CS1 of the liquid crystal display device (image light forming unit) 32. In the longitudinal section along the first direction D1, that is, the YZ plane (the unfolded Y′Z ′ plane), among the image light emitted from the liquid crystal display device 32, the upper end side of the display area 32b indicated by the alternate long and short dash line in FIG. The component emitted from the (+ Y side) is referred to as image light GLa, and the component emitted from the lower end side (−Y side) of the display area 32b indicated by the two-dot chain line in the drawing is referred to as image light GLb. FIG. 3A shows, for reference, image light GLc emitted from the upper inner position and image light GLd emitted from the lower inner position near the liquid crystal display device 32. ing.

The upper image light GLa is converted into a parallel light beam by the projection optical system 12 and passes through the light incident part B1, the light guide part B2, and the light emission part B3 of the light guide member 21 substantially along the developed optical axis AX ′. As shown, the light beam is incident on the observer's eye EY while being inclined from above the angle φ _{1 in} a parallel light flux state. On the other hand, the lower image light GLb is converted into a parallel light flux by the projection optical system 12 and substantially along the developed optical axis AX ′, the light incident part B1, the light guide part B2, and the light emission of the light guide member 21. The light passes through the part B3 and is incident on the observer's eye EY while being tilted from below the angle φ ₂ (| φ ₂ | = | φ ₁ |) in a parallel light flux state. The above angles φ ₁ and φ ₂ correspond to the upper and lower half angles of view, and are set to, for example, 6.5 °.

  Regarding the longitudinal direction of the first direction D1, the light guide device 20 does not substantially affect the image formation by the projection optical system 12, and the projection optical system 12 forms an infinite image of the liquid crystal display device 32, and Image light to be incident on the eye EY of the observer.

  FIG. 3B is a diagram for explaining an optical path in the second direction (confinement direction or synthesis direction) D2 corresponding to the cross section CS2 of the liquid crystal display device (image light forming unit) 32. Of the image light emitted from the liquid crystal display device 32 in the transverse section CS2 along the second direction (confinement direction or synthesis direction) D2, that is, the XZ plane (the X′Z ′ plane after development), it is indicated by a dashed line in the figure. The component emitted from the first display point P1 on the right end side (+ X side) toward the display area 32b shown is the image light GL1, and the left end side (−X side) toward the display area 32b shown by the two-dot chain line in the figure. The component emitted from the second display point P2 is image light GL2. 3B, for reference, in the vicinity of the liquid crystal display device 32, the image light GL3 emitted from the position on the inner right side toward the display area 32b and the position on the inner left side toward the display area 32b. The image light GL4 emitted from the camera is added.

The image light GL1 from the first display point P1 on the right side is converted into a parallel light beam by the projection optical system 12, and the light incident part B1 and the light guide part B2 of the light guide member 21 are substantially along the developed optical axis AX ′. , and it passes through the light emission unit B3, a parallel light beam state with respect to the observer's eye EY, incident inclined from the right direction of the angle theta _1. On the other hand, the image light GL2 from the second display point P2 on the left side is converted into a parallel light flux by the projection optical system 12, and the light incident part B1 of the light guide member 21 and the light guide are substantially along the developed optical axis AX ′. The light passes through the part B2 and the light emitting part B3, and is incident on the observer's eye EY with an angle θ ₂ (| θ ₂ | = | θ ₁ |) inclined from the left direction in a parallel light flux state. The above angles θ ₁ and θ ₂ correspond to the left and right half angles of view, and are set to 10 °, for example.

Regarding the lateral direction of the second direction D2, the light guide member 21 folds the image light GL1 and GL2 by reflection, and the number of reflections at that time also varies depending on the position, so that each image light GL1 and GL2 is guided. It is expressed discontinuously in the member 21. As a result, the screen is horizontally reversed as a whole in the horizontal direction, but the right half image of the liquid crystal display device 32 and the liquid crystal display device can be obtained by processing the light guide member 21 with high accuracy as will be described in detail later. The images on the left half of 32 are continuously joined without any gap. Incidentally, considering that the number of reflections light guide member within 21 of both the image light GL1, GL2 are different from each other, the exit angle theta ₁ of the right side of the image light GL1 _'the exit angle theta ₂ of the left side of the image light GL2' Is set to something different.

  As described above, the image lights GLa, GLb, GL1, and GL2 incident on the observer's eye EY are virtual images from infinity, and the image formed on the liquid crystal display device 32 is correct in the vertical first direction D1. The image formed on the liquid crystal display device 32 is reversed with respect to the second horizontal direction D2.

[D. (The optical path of image light in the horizontal direction)
FIG. 4 is a cross-sectional view illustrating a specific optical path in the second horizontal direction D2 in the first display device 100A.

The image lights GL11 and GL12 from the first display point P1 on the right side of the liquid crystal display device 32 are converted into parallel luminous fluxes by passing through the lens groups L1, L2, and L3 of the projection optical system 12, and light incident on the light guide member 21 Incident on the surface IS. The image lights GL11 and GL12 guided into the light guide member 21 repeat total reflection at the same angle on the first and second reflection surfaces 21a and 21b, and are finally emitted as a parallel light flux from the light exit surface OS. . Specifically, the image lights GL11 and GL12 are reflected by the third reflection surface 21c of the light guide member 21 as parallel light beams, and then enter the first reflection surface 21a of the light guide member 21 at the first reflection angle γ1. , Total reflection (first total reflection). Thereafter, the image lights GL11 and GL12 are incident on the second reflecting surface 21b and totally reflected (second total reflection) while maintaining the first reflection angle γ1, and then incident on the first reflecting surface 21a again. And is totally reflected (third total reflection). As a result, the image lights GL11 and GL12 are totally reflected three times on the first and second reflecting surfaces 21a and 21b, and enter the fourth reflecting surface 21d. The image lights GL11 and GL12 are reflected by the fourth reflection surface 21d at the same angle as the third reflection surface 21c, and are angled from the light emission surface OS to the second optical axis AX2 direction perpendicular to the light emission surface OS. It is emitted as a parallel light beam by theta ₁ slope.

The image lights GL21 and GL22 from the second display point P2 on the left side of the liquid crystal display device 32 are converted into parallel light beams by passing through the lens groups L1, L2, and L3 of the projection optical system 12, and light incident on the light guide member 21 Incident on the surface IS. The image lights GL21 and GL22 guided into the light guide member 21 repeat total reflection at equal angles on the first and second reflection surfaces 21a and 21b, and are finally emitted from the light exit surface OS as parallel light beams. . Specifically, the image lights GL21 and GL22 are reflected by the third reflecting surface 21c of the light guide member 21 as a parallel light beam, and then the first reflection of the light guide member 21 at the second reflection angle γ2 (γ2 <γ1). The light enters the surface 21a and is totally reflected (first total reflection). Thereafter, the image lights GL21 and GL22 enter the second reflection surface 21b and are totally reflected (second total reflection) while maintaining the second reflection angle γ2, and then enter the first reflection surface 21a again. Are totally reflected (third total reflection), are incident again on the second reflecting surface 21b and totally reflected (fourth total reflection), and are again incident on the first reflecting surface 21a and totally reflected. (5th total reflection). As a result, the image lights GL21 and GL22 are totally reflected five times on the first and second reflecting surfaces 21a and 21b and enter the fourth reflecting surface 21d. The image lights GL21 and GL22 are reflected by the fourth reflecting surface 21d at the same angle as the third reflecting surface 21c, and are angled from the light emitting surface OS to the second optical axis AX2 direction perpendicular to the light emitting surface OS. It is emitted as a parallel light beam by theta ₂ gradient.

  In FIG. 4, when the light guide member 21 is developed, a virtual first surface 121a corresponding to the first reflection surface 21a, and when the light guide member 21 is deployed, a virtual first surface 121b corresponding to the second reflection surface 21b. The 2nd surface 121b is drawn. By developing in this way, the image lights GL11 and GL12 from the first display point P1 pass through the first surface 121a twice after passing through the incident equivalent surface IS ′ corresponding to the light incident surface IS. It can be seen that the light passes through the surface 121b once, is emitted from the light exit surface OS, and enters the observer's eye EY, and the image lights GL21 and GL22 from the second display point P2 are incident corresponding to the light entrance surface IS. After passing through the equivalent surface IS ", it can be seen that it passes through the first surface 121a three times, passes through the second surface 121b twice, is emitted from the light exit surface OS, and enters the observer's eye EY. In other words, the observer observes the lens group L3 at the exit end of the projection optical system 12 existing in the vicinity of the incident equivalent surfaces IS ′ and IS ″ at two different positions.

The light beams emitted from other positions will be described. The image light GL3 emitted from the right side toward the liquid crystal display device 32 and closer to the center than the first display point P1 is parallel by the projection optical system 12. A light beam is incident on the light guide member 21 from the light incident surface IS, and is totally reflected three times on the first and second reflecting surfaces 21a and 21b of the light guide member 21 in the same manner as the image lights GL11 and GL12. It is emitted as a parallel light flux smaller inclination than the angle theta ₁ through the light exit plane OS.

The image light GL4 emitted from the position on the left side toward the liquid crystal display device 32 and closer to the center than the second display point P2 is converted into a parallel light flux by the projection optical system 12 and guided from the light incident surface IS to the light guide member. entered the 21, similar to the image light GL 21, GL22, first and second reflecting surfaces 21a of the light guide member 21 is totally reflected five times in 21b, smaller inclination than the angle theta ₂ through the light exit plane OS Is emitted as a parallel luminous flux.

  5A is a diagram for conceptually explaining a display surface of the liquid crystal display device (image light forming unit) 32, and FIG. 5B is a conceptual diagram of a virtual image of the liquid crystal display device 32 that can be seen by an observer. 5 (C) and 5 (D) are diagrams illustrating partial images constituting a virtual image. A rectangular image forming area AD provided in the liquid crystal display device 32 shown in FIG. 5A is observed as a virtual image display area AI shown in FIG. A first projection image IM1 corresponding to a portion from the center to the right side of the image forming area AD is formed on the left side of the virtual image display area AI (see FIG. 5C). Is a partial image lacking. On the right side of the virtual image display area AI, a projection image IM2 corresponding to a portion from the center to the left side of the image forming area AD of the liquid crystal display device 32 is formed as a virtual image (see FIG. 5D). The two projection images IM2 are partial images with the left side missing.

  The first partial region A10 that forms only the first projection image (virtual image) IM1 in the liquid crystal display device 32 illustrated in FIG. 5A includes the first display point P1 at the right end of the liquid crystal display device 32, for example. The image lights GL11 and GL12 that are totally reflected three times in total in the light guide portion B2 of the light guide member 21 are emitted. The second partial area A20 that forms only the second projection image (virtual image) IM2 in the liquid crystal display device 32 includes, for example, the second display point P2 at the left end of the liquid crystal display device 32, and the light guide member 21 guides the light. The image light GL21 and GL22 that are totally reflected five times in the portion B2 are emitted. The image light from the band SA extending vertically and sandwiched between the first and second partial areas A10 and A20 near the center of the image forming area AD of the liquid crystal display device 32 forms an overlapping image SI shown in FIG. doing. That is, the image light from the band SA of the liquid crystal display device 32 is totaled five times in the first projection image IM1 formed by the image light GL3 totally reflected three times in the light guide B2 and in the light guide B2. The second projection image IM2 formed by the reflected image lights GL0 and GL4 is superimposed on the virtual image display area AI. If the light guide member 21 is precisely processed and a light beam accurately collimated by the projection optical system 12 is formed, the overlapping image SI is prevented from being displaced or blurred due to the superimposition of the two projection images IM1 and IM2. be able to.

[E. (Direction of image light)
With reference to FIG. 6A, the relationship between the vertical position of the display region 32b of the liquid crystal display device 32 and the emission angle of the image light (angle characteristics of the light beam taken into the projection optical system 12 or the like) will be described. In the upper half of the liquid crystal display device 32, when the emission position (vertical object height) y in the first direction D1 increases gradually from the center of the liquid crystal display device 32 in the vertical direction, the display area 32b accordingly The emission angle μ of the image light FL gradually increases. As a result, although detailed description is omitted, the angle of the image light FL incident on the observer's eye EY gradually increases. A similar phenomenon occurs in the lower half of the liquid crystal display device 32.

  FIG. 6B is a graph illustrating the angular characteristics in the vertical direction when a virtual image is formed by the image light emitted from the liquid crystal display device 32, that is, the angular characteristics of the light beam capture in the virtual image display device 100. In the graph, the horizontal axis represents the emission position y in the first vertical direction D1 of the liquid crystal display device 32, and the vertical axis represents the effective emission of the image light FL incident on the eye EY out of the image light from the liquid crystal display device 32. Represents the angle μ. Here, the emission angle μ is positive with respect to the normal line of the liquid crystal display device 32 in the vertical direction upper side, that is, in the + y direction. As is apparent from the graph, the angle of the light beam emitted from the liquid crystal display device 32 and effectively taken into the observer's eye EY varies greatly depending on the position of the liquid crystal display device 32. More specifically, the angle is effectively utilized. The absolute value of the emission angle μ of the image light FL tends to be larger on the peripheral side than on the central side of the display area 32 b of the liquid crystal display device 32. That is, the larger the emission position y is, the larger the emission angle of the image light FL that is incident on the eye EY via the light guide device 20 from the liquid crystal display device 32 is inclined to the outside, and the maximum of the emission position y. The inclination of the emission angle of the image light FL is maximum at the value, that is, the upper end (peripheral portion) of the display area 32b. From the above situation, regarding vertical imaging, the image light FL emitted from the liquid crystal display device 32 should have directivity corresponding to the angle characteristic of the light beam capture as shown in FIG. Thus, it is considered that the light coupling efficiency from the liquid crystal display device 32 to the light guide device 20 and the eye EY can be increased, and the use of illumination light can be increased by suppressing the occurrence of luminance spots (brightness unevenness). . Note that the phenomenon as described above (the influence of the angle characteristics of the light beam capture) becomes more prominent as the angle of view of the virtual image increases. Therefore, in order to increase the angle of view of the virtual image, it is emitted from the liquid crystal display device 32. It is important to give the image light FL appropriate directivity.

  With reference to FIG. 7A, the relationship between the horizontal position of the display area 32b of the liquid crystal display device 32 and the emission angle of the image light (angle characteristics of the light beam taken into the projection optical system 12 or the like) will be described. In the right half (+ X side) of the liquid crystal display device 32, the emission position (horizontal object height) x in the second direction D2 is gradually increased from the center of the liquid crystal display device 32 in the lateral direction. As the direction increases, the emission angle ν of the image light FL from the display region 32b gradually decreases accordingly. On the other hand, the angle of the image light FL incident on the observer's eye EY increases conversely. In addition, in the left half (−X side) of the liquid crystal display device 32, the emission position in the second direction D2 (lateral object height in the second direction) is gradually separated from the center of the liquid crystal display device 32 in the horizontal direction. ) When x increases in the minus direction, the absolute value | ν | of the emission angle of the image light FL from the display region 32b gradually decreases accordingly. As a result, although detailed description is omitted, the angle of the image light FL incident on the observer's eye EY is also reduced.

  FIG. 7B is a graph illustrating the angular characteristics in the horizontal direction when a virtual image is formed by the image light emitted from the liquid crystal display device 32, that is, the angular characteristics of the light beam capture in the virtual image display device 100. In the graph, the horizontal axis represents the emission position x in the horizontal second direction D2 in the liquid crystal display device 32, and the vertical axis represents the effective emission of the image light FL incident on the eye EY out of the image light from the liquid crystal display device 32. Represents the angle ν. Here, the emission angle ν is positive with respect to the normal line of the liquid crystal display device 32 in the horizontal direction, that is, the inclination angle in the + x direction. As is apparent from the graph, the angle of the light beam emitted from the liquid crystal display device 32 and effectively taken into the observer's eye EY varies greatly depending on the position of the liquid crystal display device 32. More specifically, the angle is effectively utilized. The absolute value of the image light FL emission angle ν tends to be larger on the center side than on the peripheral side of the display area 32 b of the liquid crystal display device 32. That is, as the emission position x is smaller and closer to the center side, the emission angle of the image light FL incident on the eye EY via the light guide device 20 from the liquid crystal display device 32 is increased inward. From the above situation, with respect to the image formation in the horizontal direction, the image light FL emitted from the liquid crystal display device 32 should have directivity corresponding to the angle characteristic of the light beam capture as shown in FIG. Thus, it is considered that the light coupling efficiency from the liquid crystal display device 32 to the light guide device 20 and the eye EY can be increased, and the use of illumination light can be increased by suppressing the occurrence of luminance spots (brightness unevenness). . Note that the phenomenon as described above (the influence of the angle characteristics of the light beam capture) becomes more prominent as the angle of view of the virtual image increases. Therefore, in order to increase the angle of view of the virtual image, it is emitted from the liquid crystal display device 32. It is important to give the image light FL appropriate directivity.

  By the way, at the horizontal center of the liquid crystal display device 32, an image is mainly formed by the image light GL0 totally reflected five times in the light guide B2, but totally reflected three times in the light guide B2. An image is also formed to some extent by the image light GL0 ′. In this case, it is desirable that the emission angle has a peak in two directions of ν0 and ν0 ′ from the viewpoint of obtaining a high-luminance image.

  FIG. 8 is a diagram for explaining the angle characteristics of the light beam capturing shown in FIGS. 6B and 7B as a two-dimensional distribution. A virtual lattice is displayed on the liquid crystal display device 32, the horizontal axis x corresponding to the second direction D2, and the vertical axis x corresponding to the first direction D1. Further, the directions and sizes of the arrows DA1 and DA2 extending from the respective lattice points indicate the inclination direction and the inclination amount (that is, the azimuth angle and the inclination angle) corresponding to the peak of the light flux capture. The solid line arrow DA1 indicates the direction of taking in the light flux with respect to the image light GL2 and GL4 (GL0) in FIG. 7A that is totally reflected five times in the light guide B2, and the dotted line arrow DA2 indicates the light guide. FIG. 8B shows the direction of taking in the light flux with respect to the image lights GL1 and GL3 (GL0 ′) in FIG. As is apparent from the figure, the direction of taking in the light flux is non-uniform both in the vertical direction and in the horizontal direction. Note that the image light from the center band SA is taken in the directions of the two arrows DA1 and DA2. In other words, the image light that is coupled to the light guide member 21 via the projection optical system 12 and propagates through the light guide member 21 to reach the eye EY, or the illumination light that is the source thereof, has a peak direction with a maximum luminance of 2 Are set (specifically, the directions of arrows DA1 and DA2). However, if there is a peak of the emission angle of the image light in the direction of at least one of the arrows DA1 and DA2, sufficient luminance can be secured even in the overlapping image SI shown in FIG. Images can be formed.

[F. Control of directivity of image light in image display device]
Hereinafter, the directivity control of the image light using the directivity control of the illumination light in the image display device 11 will be described.

  FIGS. 9A to 9D are a plan view, a side view, a rear view, and a partially broken perspective view of the illumination device 31 and the liquid crystal display device 32 that constitute the image display device 11. In the image display device 11, the optical directivity changing unit 38 is disposed between the illumination device 31 and the liquid crystal display device 32, and is attached to the light emission side of the illumination device 31. Here, the illuminating device 31 includes a light source 31a that is a light emitting unit and a backlight light guide unit 31b.

  Among the illumination devices 31, a light source (light emitting unit) 31a extends along a light capturing surface IP that is one side surface of a rectangular plate-like backlight light guide unit 31b, and is a liquid crystal display device (image light forming unit). A sufficient amount of light to illuminate 32 is generated and emitted toward the backlight light guide 31b. As the light source 31a, for example, an elongated fluorescent tube or an array of a plurality of LED light sources can be applied.

  The backlight light guide portion 31b is a flat plate member as a whole, and is disposed close to and in parallel with the back of the liquid crystal display device 32. The backlight light guide 31b includes a flat plate member 31e, a reflection film 31f, and a diffusion film 31g, and has a structure in which the flat plate member 31e is sandwiched between the reflection film 31f and the diffusion film 31g. The backlight light guide 31b causes the illumination light SL from the light source 31a to enter the inside via the light capturing surface IP, guides the incident light to diffuse by reflection, and passes through the diffusion film 31g and the exit surface EP. By emitting the light toward the external liquid crystal display device 32, illumination light for illuminating the entire liquid crystal display device 32 from behind is formed.

  As shown in the graph of FIG. 10A, the illumination light emitted from the exit surface EP of the backlight light guide 31b in FIG. 9A is made uniform by the backlight light guide 31b. Light distribution characteristics or light distribution. In the graph, the right half of the horizontal axis represents the orientation angle E in the vertical Y direction of the illumination light emitted from the backlight light guide 31b, and the left half of the horizontal axis represents the illumination emitted from the backlight light guide 31b. The orientation angle E ′ in the horizontal X direction of the light is represented, and the vertical axis represents the luminance of the illumination light at each orientation angle. The illumination light emitted from the exit surface EP of the backlight light guide 31b has a main directivity direction with the highest luminance in the direction of the optical axis AX (Z direction) perpendicular to the exit surface EP. It has a luminance center (intensity peak) in the direction of the vertical optical axis AX (Z direction), and decreases as the tilt angle, that is, the orientation angles E and E ′ increase with respect to the optical axis AX. Regarding the illumination light emitted from the backlight light guide 31b, the direction of the optical axis AX (Z direction) perpendicular to the emission surface EP is the main directivity direction with the highest luminance.

  The sheet-like optical directivity changing unit 38 is attached to the exit surface EP of the backlight light guide unit 31 b and integrated with the optical directivity changing unit 38. The optical directivity changing unit 38 is a prism array sheet, and has a function of changing the light distribution characteristic (see FIG. 10A) of illumination light emitted from the exit surface EP of the backlight light guide 31b. The incident light is bent at different angles according to the position of the exit surface EP (that is, the pixel position of the liquid crystal display device 32). That is, the optical directivity changing unit 38 adjusts the light distribution characteristic which is the angular distribution of the directivity of the illumination light, thereby changing the directivity of the image light emitted from the liquid crystal display device 32 as shown in FIG. The virtual image display device 100 shown in FIG. Here, the light distribution characteristics of the optical directivity changing unit 38 are different with respect to the first direction D1 and the second direction D2. Specifically, as described with reference to FIG. 6 (A), the light beam that is inclined outward as the absolute value of the emission position y in the vertical first direction D1 increases in the display region 32b of the liquid crystal display device 32. Since the light passes through the projection optical system 12 and the light guide device 20 and is effectively captured by the observer's eye EY, the optical directivity is changed to match the angular characteristics of such light flux capture, as will be described in detail later. The directivity distribution of the image light emitted from the liquid crystal display device 32 is adjusted by the unit 38. Further, as described with reference to FIG. 7A, the light beam tilted inward as the absolute value of the emission position x in the horizontal second direction D2 increases in the display region 32b of the liquid crystal display device 32. 12 and the light guide device 20 and is effectively captured by the observer's eye EY. Similarly, the details will be described later. However, the optical directivity changing unit is matched to the angular characteristics of such light flux capturing. 38 adjusts the directivity distribution of the image light emitted from the liquid crystal display device 32. Thus, by using the optical directivity changing unit 38 to adjust the light distribution of illumination light, it is possible to efficiently use illumination light and image light.

  The optical directivity changing unit 38 is a prism array sheet having prism elements that are two-dimensionally arranged, and the exit side surface thereof is sawtooth-like in both vertical and horizontal sections due to the periodic arrangement of the prism elements, and is stepped. The deflection surface 38a. The prism elements constituting the prism array sheet are arranged with a period larger than that of the pixels of the liquid crystal display device 32, for example, but may be arranged with a period smaller than that of the pixels of the liquid crystal display device 32.

  As shown in the vertical cross section of FIG. 11, the optical directivity changing unit 38 has a prism array in which prism elements are non-uniformly arranged, and the main directivity direction of the illumination light IL depends on the position. The main directivity direction is inclined outward on the peripheral side. That is, in the prism element constituting the optical directivity changing unit 38, the slope is inclined downward in the upper area (+ Y side) with respect to the center position in the vertical direction, and the wedge angle of the slope is increased in the upper area. ω is gradually increasing. In addition, the prism element constituting the optical directivity changing unit 38 has a slope inclined upward in the lower region (−Y side) with respect to the center position in the vertical direction, and the wedge provided on the lower side is provided on the lower side. The angle ω gradually increases. The illumination light IL uniformly emitted from the backlight light guide unit 31b is given an inclination angle ε due to bending at the prism element when passing through the deflection surface 38a of the optical directivity changing unit 38, and the liquid crystal shown in FIG. The light enters the display device 32. This inclination angle ε corresponds to the main direction of the light distribution of the illumination light IL, and as illustrated in each of the area portions AV1, AV2, and AV3 constituting the upper half of the optical directivity changing unit 38, Gradually increases from the top toward the upper end. That is, the light distribution or light distribution characteristic after passing through the optical directivity changing unit 38 is closer to the upper side (+ Y side) away from the optical axis AX as shown by the broken line in FIG. It has directivity such that the angle in the main direction (the direction of the luminance center) increases outward as it goes toward the upper end region portion (peripheral portion) A21. On the other hand, as illustrated in each of the area portions AV4, AV5, AV6 constituting the lower half of the optical directivity changing unit 38, the inclination angle ε of the illumination light IL gradually increases from the center toward the lower end. It has become. That is, the light distribution or light distribution characteristic after passing through the optical directivity changing unit 38 is closer to the lower (−Y side) position away from the optical axis AX, as indicated by a broken line in FIG. In other words, it has directivity such that the angle in the main direction (the direction of the luminance center) increases outward as it goes toward the lower end region portion (peripheral portion) AV6.

  With respect to the above vertical direction, the bending or deflection of the illumination light IL by the optical directivity changing unit 38 is such that the illumination light IL is deflected further outward from the center toward the periphery, that is, the illumination light IL as a whole is outside. It's like letting it diverge. That is, the distribution of the inclination angle ε related to the bending of the illumination light IL in the vertical direction by the optical directivity changing unit 38 corresponds to the angle characteristic of the light beam capture as shown in FIG. As a result, the liquid crystal display device 32 is illuminated by the illumination light IL having an inclination angle ε corresponding to the emission angle μ of the image light FL that is emitted from now on and effectively used for virtual image formation. That is, the emission angle μ corresponding to the effective luminance center of the image light FL from the liquid crystal display device 32 and the inclination angle ε corresponding to the luminance center of the illumination light IL from the illumination device 31 can be substantially matched. become. In this way, by making the image light FL emitted from each position of the liquid crystal display device 32 and effectively used as a high-luminance component, the illumination light is not wasted, and the luminance spots of the virtual image can be reduced.

  As shown in the cross section of FIG. 12, the optical directivity changing unit 38 changes the main directivity direction of the illumination light IL according to the position, and inclines the main directivity direction inward at the center side. That is, in the prism elements constituting the prism array of the optical directivity changing unit 38, the slope is inclined to the right in the right region (+ X side) with respect to the center position with respect to the left and right. The wedge angle ξ gradually decreases. In addition, the prism element constituting the optical directivity changing unit 38 has a slope inclined to the left in the left side region (−X side) with respect to the center position in the vertical direction, and the wedge angle of the slope is more provided in the left side region. ξ gradually decreases. The illumination light IL uniformly emitted from the backlight light guide unit 31b is given an inclination angle η due to bending at the prism element when passing through the deflection surface 38a of the optical directivity changing unit 38, and the liquid crystal shown in FIG. The light enters the display device 32. The inclination angle η corresponds to the main direction of the light distribution of the illumination light IL, and as illustrated in each of the region portions AH1, AH2, and AH3 constituting the right half of the optical directivity changing unit 38, It gradually decreases from the end toward the right end. That is, the light distribution or the light distribution characteristic after passing through the optical directivity changing unit 38 is closer to the position on the optical axis AX side (−X side) as shown by the broken line in FIG. It has directivity such that the angle of the main direction (the direction of the luminance center) increases to the left as it goes to the area portion AH3. On the other hand, as illustrated in each of the region portions AH4, AH5, and AH6 constituting the left half of the optical directivity changing unit 38, the inclination angle η of the illumination light IL gradually decreases from the center toward the left end. ing. That is, the light distribution or the light distribution characteristic after passing through the optical directivity changing unit 38 is closer to the position on the optical axis AX side (+ X side) as shown by the broken line in FIG. Directivity is such that the angle in the main direction (the direction of the luminance center) increases outward as it goes toward the portion AH4.

  With respect to the above lateral direction, the bending or deflection of the illumination light IL by the optical directivity changing unit 38 is such that the illumination light IL is deflected more inward as it goes from the peripheral part to the center, that is, the illumination light IL is totally opposed. It looks like it faces the end or inside. That is, the distribution of the inclination angle η relating to the bending of the illumination light IL in the lateral direction by the optical directivity changing unit 38 corresponds to the angle characteristic of the light beam capture as shown in FIG. As a result, the liquid crystal display device 32 is illuminated by the illumination light IL having an inclination angle η corresponding to the emission angle θ of the image light FL that is emitted from now on and effectively used for virtual image formation. That is, the emission angle θ corresponding to the effective luminance center of the image light FL from the liquid crystal display device 32 and the inclination angle η corresponding to the luminance center of the illumination light IL from the illumination device 31 can be substantially matched. become. In this way, by making the image light FL emitted from each position of the liquid crystal display device 32 and effectively used as a high-luminance component, the illumination light is not wasted, and the luminance spots of the virtual image can be reduced.

  In the virtual image display device 100 of the embodiment, the optical directivity changing unit 38 forms a non-uniform distribution with respect to the directivity of the image light GL emitted from the image display device 11, so that the image display is performed according to the position of the image display device 11. Even when the angle of the light beam emitted from the apparatus 11 and effectively taken into the observer's eye EY is greatly different, the image light GL having directivity corresponding to the angle characteristic of such light beam taking-in is obtained. It can be formed, and the use efficiency of illumination light can be improved by suppressing the occurrence of luminance spots.

  In the virtual image display device 100 of the first embodiment described above and the embodiments described below, the adjustment of the directivity or light distribution characteristic of the illumination light IL or the image light GL by the optical directivity changing unit 38 is the first and second. It is not necessary to carry out for both the directions D1 and D2, and it can be carried out for only one of the first and second directions D1 and D2.

[Second Embodiment]
The virtual image display device according to the second embodiment will be described below. The virtual image display device according to the present embodiment is a modification of the virtual image display device 100 according to the first embodiment, and is the same as the virtual image display device 100 according to the first embodiment unless otherwise described.

  A liquid crystal display device (image light forming unit) 132 shown in FIGS. 13A and 13B includes an optical directivity changing unit 138 for forming a non-uniform distribution with respect to the directivity of image light. Yes.

  The liquid crystal display device (image light forming unit) 132 is a spatial light modulator, more specifically, a light transmissive liquid crystal display element. The liquid crystal display device 132 includes a liquid crystal panel 51 and a pair of polarizing filters 52a and 52b sandwiching the liquid crystal panel 51. In the liquid crystal display device (liquid crystal display element) 132, the incident-side first polarizing filter 52a and the emission-side second polarizing filter 52b are arranged to form a crossed Nicol with the liquid crystal panel 51 interposed therebetween. The liquid crystal panel 51 two-dimensionally changes the polarization direction of the illumination light IL incident from the first polarizing filter 52a side for each pixel according to the input signal, and uses the changed modulated light as the image light ML as the second polarizing filter. 52b is injected.

  The liquid crystal panel 51 includes a first substrate 72 on the incident side and a second substrate 73 on the emission side with the liquid crystal layer 71 interposed therebetween. The first substrate 72 on which the incident light LI is incident includes a prism array 72a extending along a YZ plane perpendicular to the optical axis AX, and a main body portion 72b disposed inside the prism array 72a. The prism array 72a functions as an optical directivity changing unit 138 that adjusts the directivity of the image light ML, and a large number of two-dimensionally arranged in a predetermined pattern corresponding to the transparent pixel electrode 77, that is, the pixel portion PP. It has a minute prism element PE.

  In the liquid crystal panel 51, a transparent common electrode 75 is provided on the surface of the first substrate 72 on the liquid crystal layer 71 side, and a light distribution film 76 is formed thereon, for example. On the other hand, on the surface of the second substrate 73 on the liquid crystal layer 71 side, a plurality of transparent pixel electrodes 77 arranged in a matrix and a thin film transistor (not shown) electrically connected to each transparent pixel electrode 77. And a light distribution film 78 is formed thereon, for example. Here, the inner portion of the first substrate 72 (that is, the main body portion 72b), the second substrate 73, the liquid crystal layer 71 sandwiched between them, and the electrodes 75 and 77 are used as optical active elements, that is, incident light LI. This is a part that functions as a liquid crystal device 80 for modulating the polarization state according to the input signal. Each pixel portion PP constituting the liquid crystal device 80 includes one transparent pixel electrode 77, a part of the common electrode 75, a part of both light distribution films 76 and 78, and a part of the liquid crystal layer 71. . Each pixel portion PP can be made incident by adjusting the inclination angle of the illumination light IL by each element of the prism array 72 a provided on the incident-side first substrate 72. A grid-like black matrix 79 is provided between the first substrate 72 and the common electrode 75 so as to partition each pixel portion PP.

  The prism array 72a which is the optical directivity changing unit 138 is incorporated in place of the optical directivity changing unit 38 of the first embodiment shown in FIG. 9A and the like, and is the same as in the case of the first embodiment. The illumination light incident from the backlight light guide 31b is bent outward with respect to the vertical direction, and the illumination light incident from the backlight light guide 31b is bent inward with respect to the horizontal direction.

  Specifically, as shown in the longitudinal section of FIG. 13A, the prism array 72a includes prism elements PE in which the wedge angle ω gradually increases toward the upper side (+ Y side) in the portion above the center. The illumination light IL that is uniformly emitted from the backlight light guide portion 31b of FIG. 2A is given an upward inclination angle ε when passing through the prism element PE, and is applied to the liquid crystal device 80. Incident. Although not shown, the prism array 72a includes a prism element PE in which the wedge angle ω gradually increases toward the lower side (−Y side) in the portion below the center, and the backlight The illumination light IL uniformly emitted from the light guide 31b is incident on the liquid crystal device 80 with a downward inclination angle ε when passing through the refractive surface or the deflection surface of the prism element PE. Similar to the case of the first embodiment, the distribution of the inclination angle ε corresponds to the angle characteristic of the light beam capture as shown in FIG. As a result, the liquid crystal display device 132 is illuminated by the illumination light IL with the inclination angle ε corresponding to the effective emission angle μ of the image light FL that is taken out from this and effectively used for virtual image formation. Light is not wasted, and brightness spots of the virtual image can be reduced.

  As shown in the cross section of FIG. 13B, the prism array 72a has a prism element PE in which the wedge angle ξ gradually increases toward the left side (−X side) in the right portion from the center. The illumination light IL emitted uniformly from the backlight light guide 31b in FIG. 2A is incident on the liquid crystal device 80 with a leftward tilt angle η when passing through the prism element PE. Although not shown, the prism array 72a includes a prism element PE in which the wedge angle ξ gradually increases toward the right side (+ X side) in the portion on the left side from the center. The illumination light IL uniformly emitted from 31b is incident on the liquid crystal device 80 with a downward inclination angle η when passing through the refracting surface or the deflecting surface of the prism element PE. Similar to the first embodiment, the distribution of the inclination angle η corresponds to the angle characteristic of the light beam capture as shown in FIG. 7B. As a result, the liquid crystal display device 132 is illuminated by the illumination light IL having an inclination angle η corresponding to the effective emission angle θ of the image light FL that is taken out from this and effectively used for virtual image formation. Light is not wasted, and brightness spots of the virtual image can be reduced.

  As described above, in the case of the present embodiment, the image display apparatus is configured by the illumination device 31 and the liquid crystal display device 132 excluding the optical directivity changing unit 138.

  14A and 14B are modifications of the liquid crystal display device 132 shown in FIGS. 13A and 13B. In this case, the prism array 73a is embedded in the second substrate 73 on the emission side. That is, the second substrate 73 includes a prism array 73a extending along the YZ plane perpendicular to the optical axis AX, and a main body portion 73b disposed inside the prism array 73a. The prism array 73a has a large number of prism elements PE arranged two-dimensionally in a predetermined pattern corresponding to the transparent pixel electrode 77, that is, the pixel portion PP. As shown in FIG. 14A, the prism array 73a has a prism element PE in which the wedge angle ω gradually increases toward the upper side (+ Y side) in the portion above the center of the longitudinal section. The image light ML emitted from the liquid crystal device 80 is emitted from the liquid crystal display device 132 with an upward inclination angle ε when passing through the refracting surface or the deflecting surface of the prism element PE. As shown in FIG. 14B, the prism array 73a has a prism element PE in which the wedge angle ξ gradually increases toward the left side (−X side) in the portion on the right side from the center of the cross section. The image light ML emitted from the liquid crystal device 80 is emitted from the liquid crystal display device 132 with an upward inclination angle η when passing through the refractive surface or the deflection surface of the prism element PE.

  In the virtual image display device 100 of the present embodiment, the emission direction of the image light ML can be adjusted in units of pixels of the liquid crystal display device 132. Thereby, even when the inclination of the effective image light FL (image light ML) emitted from the liquid crystal display device 132 and effectively taken into the observer's eye EY has a bias corresponding to the area on the screen. Therefore, it is possible to form the image light ML having directivity corresponding to this, and it is possible to suppress the occurrence of luminance spots and increase the use efficiency of the illumination light.

  The prism array 73a may be configured to be externally attached to the liquid crystal display device 132, such as being attached to the outside of the first and second substrates 72 and 73.

[Third Embodiment]
The virtual image display device according to the third embodiment will be described below. The virtual image display device according to the present embodiment is a modification of the virtual image display device 100 according to the first or second embodiment, and is the same as the virtual image display device 100 according to the first embodiment unless otherwise described. Shall.

  A liquid crystal display device (image light forming unit) 232 shown in FIGS. 15A and 15B includes an optical directivity changing unit 238 for forming a non-uniform distribution with respect to the directivity of image light. This is a light transmissive liquid crystal display element. In the case of the present embodiment, an image display device is configured by the liquid crystal display device (image light forming unit) 232 excluding the optical directivity changing unit 238 and the illumination device 31 (not shown).

  In the liquid crystal panel 51 of the liquid crystal display device 232, the first substrate 72 on the light incident side is disposed inside the microlens array 272a and the microlens array 272a extending along the YZ plane perpendicular to the optical axis AX. A main body portion 72b. The microlens array 272a functions as an optical directivity changing unit 238 that adjusts the directivity of the image light ML, and a large number of two-dimensionally arranged in a predetermined pattern corresponding to the transparent pixel electrode 77, that is, the pixel portion PP. Lens element LE. Here, as shown in FIG. 15A, the pitch Pm in the Y direction of the microlens array 272a is slightly larger than the pitch Pc in the Y direction of the pixel portion PP. For this reason, with respect to the Y direction or the vertical direction, the optical axis or center of the lens element LE is gradually decentered from the center of the pixel portion PP. That is, in this microlens array 272a, the eccentricity gradually increases toward the upper side (+ Y side) in the portion above the center, and the lower side (−Y side) also in the portion below the center. The eccentricity gradually increases toward. Further, as shown in FIG. 15B, the pitch Pm ′ in the X direction of the microlens array 272a is slightly larger than the pitch Pc ′ in the Y direction of the pixel portion PP. For this reason, the optical axis or center of the lens element LE is gradually decentered from the center of the pixel portion PP in the X direction or the horizontal direction. That is, in this microlens array 272a, the eccentricity gradually increases toward the left side (−X side) in the portion on the right side from the center, and also toward the right side (+ X side) in the portion on the left side from the center. The eccentricity gradually increases.

  The illumination light IL uniformly emitted from the backlight light guide portion 31b in FIG. 2A is not only condensed but also diverged when passing through the refractive surface or the deflection surface of the microlens array 272a. Thus, an upward or downward inclination angle ε is given, and a rightward or leftward inclination angle η is given to enter the liquid crystal device 80. Similar to the case of the first embodiment, the distributions of these inclination angles ε and η correspond to the angle characteristics of the light flux capturing as shown in FIGS. 6B and 7B. Yes. Thereby, the liquid crystal display device 232 is illuminated by the illumination light IL having the inclination angles ε and η corresponding to the emission angles μ and θ of the image light FL that is taken out from this and effectively used for virtual image formation. The illumination light is not wasted, and the brightness spots of the virtual image can be reduced. Note that when the microlens array 272a is used, the light beam shielded by the black matrix 79 can be reduced by condensing the illumination light IL, and further improvement in light utilization efficiency can be expected.

  FIGS. 16A and 16B are modification examples of the liquid crystal display device 232 illustrated in FIGS. 15A and 15B. In this case, the microlens array 273a is embedded in the second substrate 273 on the emission side. That is, the second substrate 273 includes a microlens array 273a extending along a YZ plane perpendicular to the optical axis AX, and a main body portion 73b disposed inside the microlens array 273a. The microlens array 273a has a large number of lens elements LE two-dimensionally arranged in a predetermined pattern corresponding to the transparent pixel electrode 77, that is, the pixel portion PP. As shown in the vertical cross section of FIG. 16A, the microlens array 273a has a structure in which the eccentricity gradually increases toward the upper side (+ Y side) in the portion above the center. The image light ML emitted from the liquid crystal device 80 is emitted from the liquid crystal display device 232 with an upward inclination angle ε when passing through the refracting surface or the deflecting surface of the lens element LE. Although illustration is omitted, the eccentricity gradually increases toward the lower side (−Y side) also in the portion below the center. Further, as shown in the cross section of FIG. 16B, the microlens array 273a has a structure in which the eccentricity gradually increases toward the left side (−X side) in the right portion from the center. The left part of the center also has a structure in which the eccentricity gradually increases toward the right side (+ X side).

  In the liquid crystal display device 232 shown in FIGS. 16A and 16B, the microlens array 272a as the optical directivity changing unit 238 can be embedded in the first substrate 72 on the incident side.

  In the virtual image display device 100 of the present embodiment, the emission direction of the image light ML can be adjusted for each pixel of the liquid crystal display device 232. Thereby, even when the inclination of the effective image light FL (image light ML) emitted from the liquid crystal display device 232 and effectively taken into the observer's eye EY has a bias corresponding to the area on the screen. Therefore, it is possible to form the image light ML having directivity corresponding to this, and it is possible to suppress the occurrence of luminance spots and increase the use efficiency of the illumination light.

  Note that the prism array 73 a may be configured to be externally attached to the liquid crystal display device 232, such as being attached to the outside of the first and second substrates 72 and 73.

[Fourth Embodiment]
The virtual image display device according to the fourth embodiment will be described below. The virtual image display device according to the present embodiment is a modification of the virtual image display device 100 according to the first embodiment, and is the same as the virtual image display device 100 according to the first embodiment unless otherwise described. .

  As shown in FIG. 17, the image display device 11 includes an illumination device 431 that is a surface light source-like light emitting unit instead of the light source 31 a shown in FIG. 2, and the backlight light guide unit 31 b is not necessary. That is, the surface light source-like light emitting unit is a planar light source that spreads two-dimensionally by itself. An optical directivity changing unit 38 is disposed between the illumination device 431 and the liquid crystal display device (image light forming unit) 32. More specifically, the optical directivity changing unit 38 is attached and integrated on the exit surface EP of the illumination device 431 on the liquid crystal display device (image light forming unit) 32 side. As in the case of the first embodiment, the optical directivity changing unit 38 can form a desired directivity distribution in the illumination light SL. As a result, the desired directivity distribution is also applied to the image light ML. Can be given. Note that the surface-emitting type illumination device (surface light source-like light emitting unit) 431 is formed by uniformly arranging two-dimensionally light emitting elements such as organic EL elements and LEDs.

[Fifth Embodiment]
The virtual image display device according to the fifth embodiment will be described below. The virtual image display device according to the present embodiment is a modification of the virtual image display device 100 according to the first to fourth embodiments, and is the same as the virtual image display device 100 according to the first embodiment unless otherwise described. Shall.

  FIG. 18 is a diagram illustrating the image display device 11 incorporated in the virtual image display device according to the fifth embodiment. In the case of the virtual image display device according to the fifth embodiment, in the image display device 11 of FIG. 2, instead of the light modulation type liquid crystal display devices (image light forming units) 32, 232, etc., a self-luminous organic EL display device. (EL display element) 532 is used. In this case, the illuminating device 31 becomes unnecessary, and the prism array 73a embedded in the organic EL display device (EL display element) 532 has a desired directivity in the emission direction of the image light ML.

  The illustrated organic EL display device 532 is described by a longitudinal section in which one pixel portion PP and its periphery are enlarged. The structure of the organic EL display device 532 will be briefly described. The organic EL display device 532 is formed on the Si substrate 61, and the insulating layer 62, the light emitting layer 63, the light transmissive cathode layer 65, It has a structure in which an adhesive layer 66, a sealing layer 67, and a light transmission substrate 68 are sequentially stacked. On the Si substrate 61, a drive circuit for the organic EL display device 532 and the like are formed, and an electrode region 61a extending from the drive circuit is connected to an anode 64 extending through the insulating layer 62 to the light emitting layer 63. The light emitting layer 63 has a light emitting region 63 a sandwiched between the anode 64 and the light transmissive cathode layer 65. A light transmissive substrate 68 is bonded onto the light transmissive cathode layer 65 with an adhesive layer 66 and a sealing layer 67 interposed therebetween. In the adhesive layer 66 sandwiched between the light transmissive cathode layer 65 and the sealing layer 67, a prism array 73a is embedded as an optical directivity changing portion 538.

  The image light ML from each pixel portion PP of the illustrated organic EL display device 532 is given, for example, an upward inclination angle ε when passing through the refracting surface or the deflecting surface of the prism array 73a. As in the second and third embodiments, the organic EL display device 532 as a whole forms, for example, image light ML having directivity with a two-dimensional distribution corresponding to the light flux capturing peak indicated by arrows DA1 and DA2 in FIG. can do.

  The prism array 73a as the optical directivity changing unit 538 includes a plurality of prism elements PE whose inclination angles are adjusted in order to adjust the directivity of the image light ML. In the illustrated example, the prism array 73 a is formed separately for each pixel of the organic EL display device 532, but may be formed over the entire display surface of the organic EL display device 532. In the illustrated example, a plurality of prism elements PE are provided in one pixel. However, the size of a single prism element PE can be increased to cover one pixel.

  In the virtual image display device 100 of the present embodiment, the emission direction of the image light ML can be adjusted in units of pixels of the organic EL display device 532. Thereby, when the inclination of the effective image light FL (image light ML) emitted from the organic EL display device 532 and effectively taken into the observer's eye EY has a local bias corresponding to the region on the screen. Even so, it is possible to form the image light ML having directivity corresponding to this, and it is possible to suppress the occurrence of luminance spots and increase the use efficiency of the illumination light.

  The prism array 73a can be replaced with a lens array having a function of converging the light beam. The prism array 73 a is not limited to the organic EL display device 532 but can be disposed on the light emission surface of the organic EL display device 532.

  The case where the organic EL display device 532 is used as the self-luminous display device incorporated in the image display device 11 has been described above. However, the self-luminous display device is not limited to the organic EL display device 532 and may be an organic EL display. Can be different types of self-luminous display devices.

[Sixth Embodiment]
The virtual image display device according to the sixth embodiment will be described below. The virtual image display device according to the present embodiment is a modification of the virtual image display device 100 according to the first to fifth embodiments, and is the same as the virtual image display device 100 according to the first to fifth embodiments unless otherwise described. Suppose that

  FIG. 19A is a diagram illustrating a light guide member 621 obtained by modifying the light guide member 21 illustrated in FIG. In the above description, the image light propagating through the light guide member 21 is totally reflected at only the two reflection angles γ1 and γ2 with respect to the first and second reflection surfaces 21a and 21b. As shown in the light guide member 621 of the modified example shown in FIG. 3, the three component image lights GL31, GL32, and GL33 are allowed to be totally reflected at reflection angles γ1, γ2, and γ3 (γ1> γ2> γ3), respectively. You can also. In this case, the image light GL emitted from the liquid crystal display device 32 is propagated in three modes, synthesized at the position of the observer's eye EY, and recognized as a virtual image. In this case, as shown in FIG. 19B, a total reflection total projection image IM21 is formed, for example, three times on the left side of the effective display area A0, and the total reflection projection is performed five times, for example, near the center of the effective display area A0. An image IM22 is formed, and a total reflection projected image IM23 is formed, for example, seven times in total on the right side of the effective display area A0.

[Seventh Embodiment]
The virtual image display device according to the seventh embodiment will be described below. Note that the virtual image display device according to the present embodiment is a modification of the virtual image display device 100 according to the first to sixth embodiments, and is the same as the virtual image display device 100 according to the first to sixth embodiments unless otherwise described. Suppose that

  20A to 20C includes the image forming apparatus 10 and a light guide device 720 as a set. The light guide device 720 includes a light guide member 721 as a part thereof. The light guide member 721 includes a light guide main body 20a and an angle conversion unit 723 that is an image extraction unit. 20A corresponds to the AA cross section of the light guide member 721 shown in FIG.

  The overall appearance of the light guide member 721 is formed by the light guide body 20a which is a flat plate extending in parallel with the YZ plane in the drawing. Moreover, the light guide member 721 has the 1st reflective surface 21a, the 2nd reflective surface 21b, and the 3rd reflective surface 21c as a side surface. The light guide member 721 includes an upper surface 21e and a lower surface 21f that are adjacent to the first, second, and third reflecting surfaces 21a, 21b, and 21c and that face each other. Further, the light guide member 721 has an angle conversion unit 723 configured by a number of micromirrors embedded in the light guide body 20a at one end in the longitudinal direction, and the light guide body 20a is disposed at the other end in the longitudinal direction. It has a structure having a prism portion PS formed so as to expand and a third reflecting surface 21c associated therewith. Although the light guide member 721 is an integral part, it can be divided into the light incident part B1, the light guide part B2, and the light emission part B3 as in the case of the first embodiment. The incident portion B1 is a portion having a third reflecting surface 21c and a light incident surface IS described later, and the light incident portion B1 is a portion having first and second reflecting surfaces 21a and 21b, and a light guide portion B2. Is a portion having an angle conversion section 723 and a light exit surface OS described later.

  The light guide main body 20a is formed of a light-transmitting resin material or the like, and takes in the image light from the image forming apparatus 10 on a back side or an observer side plane that is parallel to the XY plane and faces the image forming apparatus 10. It has a light incident surface IS and a light emitting surface OS that emits image light toward the observer's eye EY. The light guide body 20a has a rectangular inclined surface RS in addition to the light incident surface IS as a side surface of the prism portion PS, and a mirror layer 25 is formed on the inclined surface RS so as to cover it. . Here, the mirror layer 25 functions as the third reflection surface 21c which is an incident light bending portion arranged in an inclined state with respect to the light incident surface IS by cooperating with the inclined surface RS. The third reflecting surface 21c guides the image light by bending the image light that is incident from the light incident surface IS and travels in the + Z direction as a whole so as to be directed in the −X direction that is biased in the −Z direction as a whole. The main body 20a is securely coupled. Further, in the light guide main body portion 20a, an angle conversion portion 723 having a fine structure is formed along a plane on the back side of the light exit surface OS. The light guide main body 20a extends from the third reflecting surface 21c on the entrance side to the angle conversion unit 723 on the back side, and guides the image light incident inside through the prism unit PS to the angle conversion unit 723.

  The first and second reflecting surfaces 21a and 21b of the light guide member 721 are the main surfaces of the flat light guide main body 20a and are bent at the prism portion PS as two planes facing each other and extending in parallel to the XY plane. Each of the received image light is totally reflected. The image light reflected by the third reflecting surface 21c first enters the first reflecting surface 21a and is totally reflected. Next, the image light enters the second reflecting surface 21ba and is totally reflected. Thereafter, by repeating this operation, the image light is guided to the back side of the light guide device 720, that is, the −X side provided with the angle conversion unit 723.

  The angle conversion unit 723 arranged to face the light exit surface OS of the light guide body 20a is extended along the extension plane of the second reflection surface 21b on the back side (−X side) of the light guide member 721. It is formed close to a plane. The angle conversion unit 723 reflects the image light incident through the first and second reflection surfaces 21a and 21b of the light guide member 721 at a predetermined angle and bends it toward the light exit surface OS. That is, the angle conversion unit 723 converts the angle of the image light. Here, it is assumed that the image light that first enters the angle conversion unit 723 is an extraction target as virtual image light. The detailed structure of the angle conversion unit 723 will be described later with reference to FIG.

  In addition, the refractive index n of the transparent resin material used for the light guide main body 20a is assumed to be a high refractive index material of 1.5 or more. By using a transparent resin material having a relatively high refractive index for the light guide member 721, it becomes easier to guide the image light inside the light guide member 721, and the angle of view of the image light inside the light guide member 721 is compared. Can be made smaller.

  The image light emitted from the image forming apparatus 10 and incident on the light guide member 721 from the light incident surface IS is uniformly reflected and bent by the third reflection surface 21c, and the first and second reflection surfaces of the light guide member 721 are reflected. 21a and 21b are repeatedly totally reflected and proceed in a state of having a certain spread substantially along the optical axis AX. Further, the angle conversion unit 723 is bent at an appropriate angle so that it can be taken out. Injected outside from the exit surface OS. The image light emitted to the outside from the light exit surface OS enters the observer's eye EY as virtual image light. By forming the virtual image light on the retina of the observer, the observer can recognize image light such as video light by the virtual image.

  Hereinafter, the optical path of the image light in the light guide member 721 will be described. In addition, in the case of the light guide device 720 in 7th Embodiment, it functions similarly to the light guide device 20 of FIG. 1 (A) regarding the vertical first direction D1 (Y direction). On the other hand, the light guide device 720 guides image light in a number of propagation modes in the second horizontal direction D2 (X direction), and guides image light in two propagation modes. This is different from the light guide device 20 in FIG.

  As shown in FIG. 20A, among the image light emitted from the liquid crystal display device (image light forming unit) 32 of the image display device 11, the component indicated by the dotted line emitted from the central portion of the emission surface 32a is an image. The component indicated by the one-dot chain line emitted from the right side (+ X side) of the emission surface 32a as the light GL01 is the image light GL02, and the component indicated by the two-dot chain line emitted from the left side (−X side) of the emission surface 32a. Is image light GL03.

The main components of the image lights GL01, GL02, and GL03 that have passed through the projection optical system 12 are all incident at different angles on the first and second reflecting surfaces 21a and 21b after entering from the light incident surface IS of the light guide member 721, respectively. Repeat reflection. Specifically, among the image lights GL01, GL02, and GL03, the image light GL01 emitted from the central portion of the emission surface 32a of the liquid crystal display device (image light forming unit) 32 is incident on the light incident surface IS as a parallel light flux. After being reflected by the third reflecting surface 21c, the light is incident on the first reflecting surface 21a of the light guide member 721 at the standard reflection angle γ ₀ and is totally reflected. Thereafter, the image light GL01 is, while maintaining the standard reflection angle gamma _0, the first and second reflecting surfaces 21a, repeating total reflection at 21b. The image light GL01 is totally reflected N times (N is a natural number) on the first and second reflection surfaces 21a and 21b, and enters the central portion 23k of the angle conversion unit 723. The image light GL01 is reflected at a predetermined angle at the central portion 23k, and is emitted as a parallel light flux in the optical axis AX direction perpendicular to the XY plane including the light emission surface OS from the light emission surface OS. The image light GL02 emitted from one end side (+ X side) of the emission surface 32a of the liquid crystal display device 32 is incident on the light incident surface IS as a parallel light flux after passing through the projection optical system 12, and is reflected by the third reflecting surface 21c. Thereafter, the light enters the first reflecting surface 21a of the light guide member 721 at the maximum reflection angle γ ₊ and is totally reflected. The image light GL02 is totally reflected, for example, NM times (M is a natural number) at the first and second reflecting surfaces 21a and 21b, and is predetermined at the innermost peripheral portion 23h of the angle converting portion 723 (−X side). And is emitted from the light exit surface OS as a parallel light beam in a predetermined angle direction. The exit angle at this time is such that it is returned to the third reflecting surface 21c side, and is an acute angle with respect to the + X axis. The image light GL03 emitted from the other end side (−X side) of the emission surface 32a of the liquid crystal display device 32 is incident on the light incident surface IS as a parallel light flux after passing through the projection optical system 12, and is reflected by the third reflecting surface 21c. After that, the light enters the first reflecting surface 21a of the light guide member 721 at the minimum reflection angle γ ₋ and is totally reflected. The image light GL03 is totally reflected, for example, N + M times at the first and second reflecting surfaces 21a and 21b, and is reflected at a predetermined angle by the peripheral portion 23m closest to the entrance side (+ X side) of the angle conversion unit 723, and is emitted. The light is emitted as a parallel light flux from the surface OS in a predetermined angular direction. The exit angle at this time is such that it is away from the third reflecting surface 21c side, and becomes an obtuse angle with respect to the + X axis.

Here, as an example of the value of the refractive index n of the transparent resin material used for the light guide member 721, when n = 1.5, the value of the critical angle γc is γc≈41.8 °, and n = 1. If 6, the value of the critical angle γc is γc≈38.7 °. The light guide member 721 for the necessary image light is obtained by setting the minimum reflection angle γ ₋ of the reflection angles γ ₀ , γ ₊ , γ ₋ of each image light GL01, GL02, GL03 to a value larger than the critical angle γc. Can satisfy the total reflection condition.

  Hereinafter, the structure of the angle conversion unit 723 and the bending of the optical path of the image light by the angle conversion unit 723 will be described in detail with reference to FIG.

  First, the structure of the angle conversion unit 723 will be described. The angle conversion unit 723 includes a large number of linear reflection units 2c arranged in a stripe shape. That is, the angle conversion unit 723 is configured by arranging a large number of elongated reflection units 2c extending in the Y direction along the main light direction, that is, the −X direction in which the light guide member 721 extends at a predetermined pitch PT. Each reflection unit 2c is a first reflection surface 2a that is one reflection surface portion disposed on the back side, that is, the optical path downstream side, and another one reflection surface portion that is disposed on the entrance side, that is, the optical path upstream side. The second reflecting surface 2b is provided as a set. Among these, at least the second reflecting surface 2b is a partially reflecting surface that can transmit a part of light, and allows an observer to observe an external image in a see-through manner. Each reflection unit 2c is formed in a V shape or a wedge shape in the XZ sectional view by the adjacent first and second reflection surfaces 2a and 2b. More specifically, the first and second reflecting surfaces 2a and 2b are parallel to the second reflecting surface 21b and extend in a direction perpendicular to the ± X direction, which is an arrangement direction in which the reflecting units 2c are arranged, that is, Y. It extends linearly with the direction as the longitudinal direction. Furthermore, the first and second reflecting surfaces 2a and 2b are inclined at different angles (that is, different angles with respect to the XY plane) with respect to the second reflecting surface 21b with the longitudinal direction as an axis. As a result, the first reflective surfaces 2a are periodically arranged repeatedly and extend in parallel with each other, and the second reflective surfaces 2b are also periodically arranged repeatedly and extend in parallel with each other. In the specific example shown in FIG. 21A and the like, each first reflection surface 2a is assumed to extend along a direction (Z direction) substantially perpendicular to the second reflection surface 21b. Each second reflecting surface 2b extends in a direction that forms a predetermined angle (relative angle) δ in the clockwise direction with respect to the corresponding first reflecting surface 2a. Here, the relative angle δ is assumed to be, for example, 54.7 ° in a specific example.

  In the specific example shown in FIG. 21A and the like, the first reflecting surface 2a is assumed to be substantially perpendicular to the second reflecting surface 21b, but the direction of the first reflecting surface 2a is the light guide device. 720 is adjusted as appropriate according to the specifications of 720, and makes any inclination angle in the range of, for example, 80 ° to 100 ° counterclockwise with respect to the second reflecting surface 21b with reference to the + X direction. And can. Further, the direction of the second reflecting surface 2b can be any inclination angle in a range of, for example, 30 ° to 40 ° counterclockwise with respect to the + X direction. As a result, the second reflecting surface 2b has any relative angle within a range of 40 ° to 70 ° with respect to the first reflecting surface 2a.

  The reflection unit 2c including the pair of reflection surfaces 2a and 2b is formed, for example, by forming a film such as aluminum vapor deposition on one inclined surface of the underlying V groove, and then filling the resin in the light guide device 720 by filling with resin. Embedded in.

  Hereinafter, the bending of the optical path of the image light by the angle conversion unit 723 will be described in detail. Here, of the image light, the image light GL02 and the image light GL03 that enter the both ends of the angle conversion unit 723 are illustrated, and the other optical paths are the same as these, and thus illustration and the like are omitted.

First, as shown in FIGS. 21A and 21B, the image light GL02 guided by the reflection angle γ ₊ having the largest total reflection angle among the image light is the light incident surface IS of the angle conversion unit 723. The light is incident on one or more reflection units 2c arranged in the peripheral portion 23h on the -X side farthest from (see FIG. 20A). In the reflection unit 2c, the image light GL02 is first reflected by the first reflection surface 2a on the back side, that is, the −X side, and then reflected by the second reflection surface 2b on the entrance side, that is, the + X side. The image light GL02 that has passed through the reflection unit 2c is emitted from the light exit surface OS shown in FIG. 20A or the like without passing through the other reflection unit 2c. That is, the image light GL02 is bent to a desired angle by one pass through the angle conversion unit 723 and taken out to the viewer side.

Further, as shown in FIGS. 21A and 21C, the image light GL03 guided at the reflection angle γ ₋ having the smallest total reflection angle is included in the light incident surface IS (see FIG. The light enters one or more reflection units 2c arranged in the peripheral portion 23m on the + X side closest to (A). In the reflection unit 2c, as in the case of the image light GL02, the image light GL03 is first reflected by the first reflection surface 2a on the back side, that is, the −X side, and then the second light on the entrance side, that is, the + X side. Is reflected by the reflecting surface 2b. The image light GL03 that has passed through the reflection unit 2c is bent to a desired angle by one pass through the angle conversion unit 723 and taken out to the viewer without passing through the other reflection unit 2c.

Here, in the case of the two-stage reflection on the first and second reflecting surfaces 2a and 2b as described above, as shown in FIGS. 21 (B) and 21 (C), each image light is incident. The bending angle ψ, which is the angle between the direction and the direction at the time of injection, is ψ = 2 (R−δ) (R: right angle). That is, the bending angle ψ is constant regardless of the incident angle with respect to the angle conversion unit 723, that is, the values of the reflection angles γ ₀ , γ ₊ , γ _{− and the} like that are the total reflection angles of each image light. Thereby, as described above, a component having a relatively large total reflection angle in the image light is incident on the −X side peripheral portion 23h side of the angle conversion unit 723, and a component having a relatively small total reflection angle is converted into an angle. Even when the light is incident on the + X side peripheral portion 23m side of the portion 723, it is possible to efficiently extract the image light in an angle state in which the image light is collected on the observer's eye EY as a whole. Since the image light is extracted with such an angular relationship, the light guide member 721 can pass the image light only once without passing the image light a plurality of times in the angle conversion unit 723, and the image light can be transmitted with little loss. It can be extracted as virtual image light.

Further, in the optical design such as the shape and refractive index of the light guide member 721 and the shape of the reflection unit 2c constituting the angle conversion unit 723, by appropriately adjusting the angle etc. through which the image light GL02, GL03 and the like are guided, The image light emitted from the light exit surface OS can be incident on the observer's eye EY as virtual image light with the overall symmetry maintained around the basic image light GL01, that is, the optical axis AX. Here, the angle θ ₁₂ (θ ₁₂ ′ within the light guide device 720) with respect to the X direction or the optical axis AX of the image light GL02 at one end, and the angle θ ₁₃ (with respect to the X direction or the optical axis AX of the image light GL03 at the other end. It is assumed that θ ₁₃ ′) in the light guide device 720 is approximately equal in size and opposite to the light guide device 720. That is, the image light is emitted to the eye EY in a symmetric state about the optical axis AX. Thus, the angle θ ₁₂ and the angle θ ₁₃ are equal to each other and are symmetrical with respect to the optical axis AX, so that the angle θ ₁₂ and the angle θ ₁₃ are half the horizontal angle of view. Horizontal half angle of view.

  As already described, the first reflecting surface 2a or the second reflecting surface 2b constituting the group of reflecting units 2c have a constant pitch and are parallel to each other. Thereby, the image light which is the virtual image light incident on the eye EY of the observer can be made uniform, and the deterioration of the quality of the observed image can be suppressed. A specific numerical range of the pitch PT that is an interval between the reflection units 2c constituting the angle conversion unit 723 is 0.2 mm or more, and more preferably 0.2 mm to 1.3 mm. By being in this range, the image light to be taken out can be prevented from being affected by diffraction in the angle conversion unit 723, and the lattice fringes by the reflection unit 2c can be made inconspicuous for the observer.

  Even when the light guide member 721 described above is used, the angular characteristics of the light beam taking-in of the image light emitted from the liquid crystal display device 32 and passing through the projection optical system 12 are different in the vertical direction and the horizontal direction. Regarding the direction D1 (Y direction), as in the tendency or characteristic shown in FIG. On the other hand, with respect to the horizontal second direction D2 (X direction), for example, the inclination angle of the image light tends to increase at overlapping portions of images having different numbers of reflections on the first and second reflection surfaces 21a and 21b. That is, there is no tendency for the central image light to be taken inwardly, and it is necessary to estimate the peak direction in which the image light is taken in for each screen position by simulation or the like.

  In the case of the virtual image display device 100 according to the seventh embodiment, similarly to the virtual image display device 100 according to the first embodiment, the image forming apparatus 10 including the optical directivity changing unit 38 has desired directivity for image light. Can be made. As a result, even if the tilt of the effective image light ML emitted from the liquid crystal display device 232 and effectively taken into the observer's eye EY has a deviation corresponding to the position or area on the screen, this can be handled. By forming the image light ML having directivity, the use efficiency of the illumination light can be enhanced by suppressing the occurrence of luminance spots.

[Eighth Embodiment]
The virtual image display device according to the eighth embodiment will be described below. Note that the virtual image display device according to the present embodiment is a modification of the virtual image display device 100 according to the seventh embodiment, and unless otherwise specified, is assumed to be the same as the virtual image display device 100 according to the seventh embodiment.

  As shown in FIGS. 22A and 22B, in the case of this embodiment, the angle conversion unit 923 of the light guide member 721 has a large number of image light reflecting surfaces 2d arranged in the X direction at a predetermined pitch. It has a structure. These image light reflecting surfaces 2d extend in a strip shape with the main light direction being the direction extending perpendicularly to the −X direction in which the image light reflecting surfaces 2d are arranged, that is, the Y direction as the longitudinal direction. These image light reflecting surfaces 2d are parallel to each other and form the same angle τ with respect to the second reflecting surface 21b. The image light reflecting surface 2d is a partially reflecting surface that transmits part of the light component of the image light and reflects the rest by adjusting the reflectance. The adjacent image light reflecting surfaces 2d are connected by a boundary portion 2e that does not have a function as a reflecting surface or the like for extracting image light. As a result, the image light reflecting surfaces 2d are arranged in a separated state periodically and repeatedly along the main light direction, that is, along the Z direction, and extend parallel to each other. The image light reflecting surface 2d is formed, for example, by forming a film such as aluminum vapor deposition on one slope of the underlying V groove, and is embedded in the light guide member 721 by filling with resin thereafter.

As shown in FIG. 22A, the image light GL02 totally reflected by the first and second reflecting surfaces 21a and 21b of the light guide member 721 at the minimum reflection angle γ ₋ has passed through the angle conversion unit 923 a plurality of times. after reaching the periphery 23h of the innermost of the angle conversion unit 923 (-X side), the reflection at the peripheral portion 23h, the eye through the light exit plane OS at an angle theta ₁₂ relative to the optical axis AX of the eye EY It is emitted as a parallel light beam toward EY. On the other hand, as shown in FIG. 22B, the image light GL03 totally reflected by the first and second reflecting surfaces 21a and 21b of the light guide member 721 at the maximum reflection angle γ ₊ is the most of the angle conversion unit 923. It reaches the peripheral portion 23m of the inlet side (+ X side), the reflection at the peripheral portion 23m, and is emitted as a parallel light beam toward the eye EY from the light exit surface OS at an angle theta ₁₃ relative to the optical axis AX of the eye EY .

  In the present embodiment, instead of incorporating the optical directivity changing units 38 and 838 into the illumination device 31, the optical directivity is applied to the liquid crystal display devices (image light forming units) 132 and 232 as in the second and third embodiments. The sex changer 138, 238 can also be incorporated.

[Ninth Embodiment]
The virtual image display device according to the ninth embodiment will be described below. Note that the virtual image display device according to the present embodiment is a modification of the virtual image display device 100 according to the seventh embodiment, and unless otherwise specified, is assumed to be the same as the virtual image display device 100 according to the seventh embodiment.

  As shown in FIG. 23, the virtual image display device 100 can include a hologram element 1025 in place of the prism portion PS and the mirror layer 25 (see FIG. 2A, etc.). In this case, the image display device 11 includes the illumination device 31 that includes a light source 1031a including, for example, LEDs that generate light beams of three colors. In addition, a hologram element 1025 is affixed on the extended surface of the second reflecting surface 21 b at the incident side end of the light guide member 721. The hologram element 1025 has a three-layer hologram layer corresponding to the three colors generated by the light source 1031a. Accordingly, the hologram element 1025 has a function of reflecting each color light from the image display device 11 in a desired direction as a virtual mirror formed in the vicinity of the second reflection surface 21b at the incident side end. . That is, the hologram element 1025 can adjust the reflection direction of the image light. With this hologram element 1025, image light can be efficiently taken into the light guide member 721.

  In addition, it can replace with the angle conversion part 723 (refer FIG. 21 (A)), and a hologram element can also be used. In addition, a hologram element can be used instead of the mirror or the half mirror on the third reflection surface 21c or the fourth reflection surface 21d of the light guide member 721 of the light guide device 720.

[Others]
Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the gist thereof. Such modifications are also possible.

  In the first to third embodiments and the like, the emission angle of the image light FL or the image light GL is greatly inclined outward as the emission position increases away from the center of the liquid crystal display device 32 in the vertical direction, and from the left and right. Although it is assumed that the smaller the exit position toward the center, the greater the inward inclination, the case where the projection optical system 12 and the light guide device 20 having the angle characteristics of the light flux capturing different from such a tendency is used. Techniques can be used. For example, when the light guide device 20 guides the image light in the vertical direction instead of the horizontal direction, the emission angle of the image light FL has an inclination characteristic in which the vertical and horizontal are interchanged. In this case, the light distribution characteristics given by the optical directivity changing units 38, 138, 238 and the like are also interchanged vertically and horizontally. The same applies to the seventh embodiment. In the case where the light guide device 720 guides image light in the vertical direction instead of the horizontal direction, the light distribution characteristics provided by the optical directivity changing unit 38 are also changed in the vertical and horizontal directions. Become.

  In the above embodiment, the optical directivity changing units 38, 138, and 238 are flat members, but the optical directivity changing units 38, 138, and 238 are replaced with thick lenses, prisms, and diffractive optical elements. You can also. By forming the optical directivity changing section from a diffractive optical element, the degree of freedom in adjusting directivity increases.

  In the first embodiment and the like, the optical directivity changing unit 38 is a single prism array sheet, but can be divided into a plurality of sheet portions. For example, it can be divided into a plurality of parts with respect to the vertical Y direction, or can be divided into a plurality of parts with respect to the horizontal X direction, and different prism shapes can be set for each part.

  In the above embodiment, the prism array 72a, the microlens array 273a, and the like are used. However, a diffractive optical element or the like can be used instead.

  Although not specifically described in the second and third embodiments, the contrast can be improved by inserting a phase difference compensation plate between the liquid crystal panel 51 and at least one of the pair of polarizing filters 52a and 52b.

  In the above description, the transmissive liquid crystal display device 32 or the like is used as the image light forming unit. However, the image light forming unit is not limited to the transmissive liquid crystal display device, and various types can be used. For example, a configuration using a reflective liquid crystal display device is possible, and a digital micromirror device or the like can be used instead of the liquid crystal display device 32.

  In the above description, in the first and second reflecting surfaces 21a and 21b, image light is totally reflected and guided by the interface with air without applying a mirror, a half mirror, or the like on the surface. The total reflection includes reflection formed by forming a mirror coat or a half mirror film on the whole or a part of the first and second reflection surfaces 21a and 21b. For example, after the incident angle of the image light satisfies the total reflection condition, the first and second reflection surfaces 21a and 21b are subjected to mirror coating or the like to reflect substantially all the image light. Cases are also included. In addition, as long as image light with sufficient brightness can be obtained, the first and second reflecting surfaces 21a and 21b may be entirely or partially coated with a somewhat transmissive mirror.

  In the above description, the light incident surface IS and the light exit surface OS are arranged on the same plane. However, the present invention is not limited to this. For example, the light incident surface IS is on the same plane as the first reflecting surface 21a. The light emission surface OS may be arranged on the same plane as the second reflection surface 21b.

  In the above description, the light guide member 21 extends in the horizontal direction in which the eyes EY are arranged. However, the light guide member 21 can be extended in the vertical direction. In this case, the optical panels 110 are arranged in parallel, not in series.

  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 virtual image display device 100 according to the above-described embodiment, the display devices 100A and 100B (specifically, the image forming device 10, the light guide device 20, and the like) are provided for each of the right eye and the left eye. However, for example, the image forming apparatus 10 and the light guide device 20 may be provided only for either the right eye or the left eye so that the image is viewed with one eye.

  In the above embodiment, the first optical axis AX1 passing through the light incident surface IS and the second optical axis AX2 passing through the light incident surface IS are parallel, but these optical axes AX1 and AX2 are made non-parallel. You can also.

  In the above embodiment, the display brightness of the liquid crystal display device 32 is not particularly adjusted, but the display brightness can be adjusted according to the range and overlap of the projection images IM1 and IM2 as shown in FIG. .

  In the above embodiment, the see-through is given priority by setting the reflectance of the half mirror layer 28 provided on the fourth reflecting surface 21d of the light guide member 21 to 20%. However, the reflectance of the half mirror layer 28 is set to 50% or more. Priority can be given to light. The half mirror layer 28 does not need to be formed only in a part of the fourth reflective surface 21d, but can be formed on the entire surface of the fourth reflective surface 21d. The half mirror layer 28 can also be formed on the third surface 23 c of the light transmission member 23.

  In addition, the pitch PT of the arrangement of the reflection units 2c constituting the angle conversion unit 723 is not limited to the case where all the first reflection surfaces 2a are the same, and there is a certain difference in each pitch PT. Shall also be included.

  In the above description, the see-through type virtual image display device is described, but the angle conversion unit 723 and the like can also be applied to a virtual image display device other than the see-through type. In addition, when it is not necessary to observe an external field image, it is possible to make the light reflectivity of both the first and second reflecting surfaces 2a and 2b substantially 100%.

  In the above description, the inclination angle of the mirror layer 25 and the inclined surface RS constituting the prism part PS is not particularly mentioned. However, the present invention makes the inclination angle of the mirror layer 25 and the like in the application and other specifications with respect to the optical axis AX. Depending on the value, various values can be used.

  In the above description, the V-shaped groove formed by the reflection unit 2c is illustrated with the tip sharpened, but the shape of the V-shaped groove is not limited to this, and the tip is cut flat. It may be one that has an R (roundness) at the tip.

  In the above description, the light guide devices 20 and 720 including the light incident part B1, the light guide part B2, and the light emitting part B3 are used. However, it is necessary to use a plane mirror in the light incident part B1 and the light emitting part B3. Alternatively, a lens-like function can be provided by a spherical or aspherical curved mirror. Furthermore, as shown in FIG. 24, a prism or block-shaped relay member 1125 separated from the light guide B2 can be used as the light incident part B1, and the incident and exit surfaces and the reflective inner surface of the relay member 1125 are lens-like. It can also have a special function. The light guide body 26 constituting the light guide section B2 is provided with first and second reflection surfaces 21a and 21b for propagating the image light GL by reflection. The reflection surfaces 21a and 21b are They do not have to be parallel to each other and can be curved surfaces.

  2a, 2b ... reflective surface, 2c ... reflective unit, 2d ... image light reflective surface, 10 ... image forming device, 11 ... image display device, 12 ... projection optical system, 20,720 ... light guide device, 21, 321 ... guide 21a, 21b, 21c, 21d ... 1st-4th reflective surface, 23 ... Light transmission member, 23h, 23m ... Peripheral part, 23k ... Central part, 28 ... Half mirror layer, 31 ... Illumination device, 31a ... Light source (light emitting part), 31b ... Backlight light guide part, 31e ... Flat plate member, 32, 132, 232 ... Liquid crystal display device (image light forming part, liquid crystal display element), 34 ... Drive control part, 38, 138, 238 , 538, 838 ... optical directivity changing unit, 51 ... liquid crystal panel, 72a ... prism array, 73a ... prism array, 80 ... liquid crystal device, 100 ... virtual image display device, DESCRIPTION OF SYMBOLS 100A, 100B ... Display apparatus, 110 ... Optical panel, 272a ... Micro lens array, 431 ... Illumination device, 532 ... EL display device, 1025 ... Hologram element, 1031a ... Light source, A10, A20 ... Partial area, AH1-AH6 ... Area Part, AV1 to AV6 ... area part, AX, AX1, AX2 ... optical axis, B1 ... light incident part, B2 ... light guide part, B3 ... light emission part, B4 ... see-through part, CS1 ... longitudinal section, CS2 ... transverse section D1 ... 1st direction, D2 ... 2nd direction, EY ... Eye, FL ... Image light, GL ... Image light, IL ... Illumination light, IM1, IM2 ... Projection image, IS ... Light incident surface, LE ... Lens element, LI ... incident light, ML ... image light, OS ... light exit surface, PE ... prism element, PP ... pixel portion, SI ... overlapping image,

Claims (17)

An image display device for forming image light;
A projection optical system for forming a virtual image by the image light emitted from the image display device;
A light incident part that takes in the image light that has passed through the projection optical system and a light guide that guides the image light taken from the light incident part by total reflection at first and second reflection surfaces that extend opposite to each other. A light guide device, and a light emitting unit that extracts the image light that has passed through the light guide unit to the outside, and
An optical directivity changing unit that changes the directivity of the image light emitted from the image display device to form the non-uniform distribution;
A virtual image display device.   The virtual image display device according to claim 1, wherein the optical directivity changing unit bends light at a different angle in accordance with a position of the image display device with respect to the first direction.   The virtual image display device according to claim 2, wherein the optical directivity changing unit bends light at different angles depending on a position of the image display device with respect to a second direction perpendicular to the first direction.   The virtual image display device according to claim 3, wherein the optical directivity changing unit has different light distribution characteristics that are angular distributions of directivity with respect to the first direction and the second direction.   The virtual image display according to any one of claims 1 to 4, wherein the image display device includes an illumination device and an image light forming unit that controls the light from the illumination device to form the image light. apparatus. The illumination device includes a light emitting unit and a backlight light guide unit that spreads a light beam from the light emitting unit in a surface light source shape,
The virtual image display device according to claim 5, wherein the optical directivity changing unit is disposed between the backlight light guide unit and the image light forming unit. The illumination device has a surface light source-like light emitting unit,
The virtual image display device according to claim 5, wherein the optical directivity changing unit is disposed between the surface light source-like light emitting unit and the image light forming unit.   The virtual image display device according to claim 6, wherein the optical directivity changing unit is at least one of a prism array sheet, a Fresnel lens, a diffractive optical element, and a microlens array.   The optical directivity changing section is attached to the backlight light guide section or the surface light source-like light emitting section and integrated with the backlight light guide section. The virtual image display device described.   The optical directivity changing unit passes a plurality of region portions through which illumination light from the backlight light guide unit or the surface light source-like light emitting unit passes so that the main directivity directions having the highest luminance are different from each other. The virtual image display device according to any one of claims 6 to 8, further comprising:   The virtual image display device according to claim 10, wherein the optical directivity changing unit includes a prism array having a different shape corresponding to the plurality of region portions. The first direction corresponds to a folding direction perpendicular to the first and second reflecting surfaces of the light guide device, and the second direction is parallel to the first and second reflecting surfaces of the light guide device. Corresponding to the non-folding direction perpendicular to the first direction;
The virtual image display device according to any one of claims 1 to 11, wherein a plurality of peak directions in which luminance is maximized are set in at least one of the first direction and the second direction.   The virtual image display device according to claim 12, wherein a plurality of peak directions in which the luminance is maximized are set in the second direction.   The virtual image display device according to claim 5, wherein the optical directivity changing unit is built in or externally attached to the image light forming unit. The image light forming unit is an EL display element,
The virtual image display device according to claim 14, wherein the optical directivity changing unit is arranged on a light emission side of a pixel portion of the EL display element. The image light forming unit is a light transmissive liquid crystal display element,
The virtual image display device according to claim 14, wherein the optical directivity changing unit is disposed on at least one of a light incident side and a light emission side of a pixel portion of the liquid crystal display element. The light guide unit has a first reflection surface and a second reflection surface that are arranged in parallel to each other and enable light guide by total reflection,
The light incident portion has a third reflecting surface that forms a predetermined angle with respect to the first reflecting surface;
The virtual image display device according to any one of claims 1 to 16, wherein the light emitting unit includes a fourth reflecting surface that forms a predetermined angle with respect to the first reflecting surface.

Images