A thickness of a tapered part provided at the deeper side (−X side) in a light guide direction of a light transmission member is smaller toward the deeper side, and thus, a reflection angle of ghost light that has passed through a fourth reflection surface provided with a half mirror layer and reached the light transmission member gradually becomes smaller within the tapered part and no longer satisfies a total reflection condition, and the light is ejected to the outside in the position diverging from an eye of an observer. That is, the tapered part may prevent the ghost light from reaching the eye and good see-through observation can be realized.
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1. A virtual image display system comprising:
an image display device that forms image light;
a projection system that allows the image light output from the image display device to enter;
a light guide member having an integrated block shape that has a light guide part, a light-incident part allowing the image light from the projection system to enter the light guide part, and a light-exiting part that outputs the image light guided by the light guide part to the outside, and enables observation of the image light via the light-exiting part; and
a light transmission member that enables observation of external light by being combined with the light guide member,
wherein the light guide part has a first reflection surface and a second reflection surface that are provided in parallel to each other and enable light guide by total reflection,
the light-incident part has a third reflection surface at a predetermined angle with respect to the first reflection surface,
the light-exiting part has a fourth reflection surface at a predetermined angle with respect to the first reflection surface,
a half mirror is provided on the fourth reflection surface, and
the light transmission member includes a see-through aiding part at least having a first surface provided in parallel to a transmission surface opposed to the fourth reflection surface and the second reflection surface, and a light blocking part that is provided nearer a light guide direction side of the light guide member than the see-through aiding part and prevents visible light from the light transmission member from being guided to the light guide member once the visible light passes through the fourth reflection surface.
2. The virtual image display system according to
3. The virtual image display system according to
the tapered part includes a first tapered surface at an obtuse angle with respect to the first surface and a second tapered surface at an obtuse angle with respect to the second surface.
4. The virtual image display system according to
5. The virtual image display system according to
6. The virtual image display system according to
7. The virtual image display system according to
8. The virtual image display system according to
9. The virtual image display system according to
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1. Technical Field
The present invention relates to a virtual image display system such as a head-mounted display mounted on a head.
2. Related Art
Recently, as virtual image display systems that enable formation and observation of virtual images like head-mounted displays, various systems of a type of guiding image light from a display device to an eye of an observer using a light guide plate have been proposed.
In the virtual image display systems, for superimposition of image light and external light, see-through optical systems have been proposed (see Patent Document 1 (JP-A-2006-3879) and Patent Document 2 (JP-A-2010-224473)).
However, in the system described in Patent Document 1 and the like, seeing through is realized by an eye division method using a light guide optical system having a smaller output aperture than the eye size, and it is difficult to make the display size of the virtual image larger. Further, since the light guide optical system smaller than the eye size is used, it is difficult to make the effective pupil diameter (lighting diameter that enables introduction of virtual images, also referred to as “eye ring diameter”) for matching with the individual pupil distances of humans. Furthermore, since the output aperture and the casing of the light guide optical system is placed physically near the eye, a blind spot is produced and seeing through is not complete.
Note that, as an optical system for head-mounted display, there is one having a light guide pipe that may advance plural light modes having different light guide angles (see Patent Document 3 (JP-A-2008-535001)). It is conceivable that a see-through display system is formed by using a half mirror as the third optical surface at the output side and making the transmitted light through the third optical surface travel straight (for example, adding a prism) in the optical system.
However, in the optical system in Patent Document 3, on the assumption that images by plural light modes are misaligned with one another, a liquid crystal panel is illuminated by collimated lights set at different incident angles with respect to each light mode. Further, by changing the display contents in the respective light modes and sequentially executing displays of the respective light modes, the images of the respective light modes are joined and a whole image is obtained. In this case, one liquid crystal panel should display the center image and the right and left images forming the whole image while changing them with time differences, and the virtual image display system becomes complicated and the images for observation become darker.
Besides, a virtual image display system that enables observation of virtual images by superimposition on external light using a light guide member having a light-exiting part covering the view without necessity to join the images with time differences is conceivable, however, it is not easy to display a large image, and, when a member such as a prism for seeing through is connected to the light guide member, ghost light is generated by the member and the ghost light becomes easier to reach.
An advantage of some aspects of the invention is to provide a virtual image display system that can realize see-through observation and suppress observation of ghost light.
A virtual image display system according to an aspect of the invention includes (a) an image display device that forms image light, (b) a projection system that allows the image light output from the image display device to enter, (c) a light guide member having an integrated block shape that has a light guide part, a light-incident part allowing the image light from the projection system to enter the light guide part and a light-exiting part that outputs the image light guided by the light guide part to the outside, and enables observation of the image light via the light-exiting part, and (d) a light transmission member that enables observation of external light by being combined with the light guide member, wherein (e) the light guide part has a first reflection surface and a second reflection surface that are provided in parallel to each other and enable light guide by total reflection, the light-incident part has a third reflection surface at a predetermined angle with respect to the first reflection surface, the light-exiting part has a fourth reflection surface at a predetermined angle with respect to the first reflection surface, (f) a half mirror such as a half mirror layer is provided on the fourth reflection surface, and (g) the light transmission member includes (g1) a see-through aiding part at least having a first surface provided nearly in parallel to a transmission surface opposed to the fourth reflection surface and the second reflection surface, and (g2) a light blocking part that is provided nearer a light guide direction side of the light guide member than the see-through aiding part and prevents light from the light transmission member from being guided to the light guide member.
In the virtual image display system, the image light reflected by the third reflection surface of the light-incident part is propagated while being totally reflected by the first and second reflection surfaces of the light guide part, and reflected by the fourth reflection surface of the light-exiting part and enters an eye of an observer as a virtual image. In this regard, the light guide member can be integrally fabricated with high accuracy to have a polygonal outer shape, and the virtual image can be observed with high accuracy via the light guide member. Further, by combining the light guide member and the light transmission member, see-through observation can be realized via the see-through aiding part and superimposition of an external image on the virtual image may be observed. Furthermore, the light blocking part provided at the light guide direction side, i.e., the deeper side in the light guide direction of the light transmission member prevents the light from the light transmission member from being guided to the light guide member, and thus, luminous flux that has passed through the half mirror such as a half mirror layer, for example, and reached inside of the light transmission member is processed not to be ghost light by the light transmission member, and the ghost light may be prevented from being returned to the light guide member.
In a specific aspect of the invention, in the virtual image display system, the light blocking part is a tapered part having a thickness smaller toward the light guide direction side. In this case, the reflection angle of the ghost light that has passed through the half mirror and reached the light transmission member gradually becomes smaller within the tapered part and no longer satisfies a total reflection condition, and the light is ejected to the outside in the position diverging from the eye of the observer. That is, the ghost light may be suppressed from reaching the eye by the tapered part.
In another aspect of the invention, the light transmission member has a second surface provided nearly in parallel to the first reflection surface and a first surface provided nearly in parallel to the second reflection surface, and the tapered part includes a first tapered surface at an obtuse angle with respect to the first surface and a second tapered surface at an obtuse angle with respect to the second surface. In this case, also the part sandwiched between the first surface and the second surface functions as the see-through aiding part and the ghost light maybe ejected to the outside by the tapered part outside of the see-through aiding part.
In still another aspect of the invention, the light blocking part is a part having a roughened surface. In this case, unwanted light that has reached the light transmission member is diffused by the light blocking part and becomes hard to be returned to the light guide member as ghost light.
In yet another aspect of the invention, the light blocking part is a part having a surface to which light-absorbing paint is applied. In this case, the unwanted light that has reached the light transmission member is absorbed by the light blocking part and becomes hard to be returned to the light guide member as ghost light.
In still yet another aspect of the invention, a number of reflections in the light guide part of first image light output from a first partial area in the image display device is different from a number of reflections in the light guide part of second image light output from a second partial area different from the first partial area with respect to a confinement direction in which an optical path is folded by reflection when the light is guided are different from each other. In this case, using image lights at different numbers of reflections, the angular width of the output angle of the image lights output from the light-exiting part may be taken wider. That is, the image lights from different partial areas or display areas in the image display device may be taken in at relatively wider angles of view, and the display size of the virtual image observed through the light-exiting part may be secured larger. As described above, according to the structure of extracting image lights at different numbers of reflection, the light-exiting part maybe made larger to cover the eye without making the light guide part so much thicker, and good see-through observation may be realized.
In further another aspect of the invention, the confinement direction is a direction in parallel to a section containing a first optical axis passing through the projection system and a normal line of the third reflection surface. Regarding the image lights from different positions with respect to the confinement direction, the numbers of reflections in the light guide part may be made different by making the output angles, i.e., the incident angles to the light-incident part different from one another.
In still further another aspect of the invention, the light guide member and the light transmission member are independently integrally molded by injection molding. In this case, the light guide member and the light transmission member may be mass-produced using the injection molding technology.
In still yet further another aspect of the invention, the light guide member and the light transmission member are respectively molded using a heat polymerization resin material. In this case, lightweight and safety may be improved by the resin and stable and accurate molding can be performed by thermosetting.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
As below, a virtual image display system according to one embodiment of the invention will be explained with reference to the drawings.
A. Appearance of Virtual Image Display System
A virtual image display system 100 of the embodiment shown in
B. Structure of Display
As shown in
The image forming unit 10 has an image display unit 11 and a projection system 12. Of them, the image display unit 11 has an illumination device 31 that outputs two-dimensional illumination light SL, a liquid crystal display device 32 as a transmissive spatial light modulation device, and a drive control part 34 that controls the operation of the illumination device 31 and the liquid crystal display device 32.
The illumination device 31 has a light source 31a that generates light containing three colors of red, green, blue, and a backlight light guide part 31b that diffuses the light from the light source 31a into luminous flux having a rectangular section. The liquid crystal display device 32 spatially modulates the illumination light SL from the illumination device 31 and forms image light to be displayed as a moving image or the like. The drive control part 34 includes a light source drive circuit 34a and a liquid crystal drive circuit 34b. The light source drive circuit 34a supplies electric power to the light source 31a of the illumination device 31 and outputs the illumination light SL with stable illuminance. The liquid crystal drive circuit 34b outputs an image signal or a drive signal to the liquid crystal display device 32, and thereby, forms color image light as an original of a moving image or a still image as a transmittance pattern. Note that the liquid crystal drive circuit 34b may be provided with an image processing function, or an external control circuit may be provided with the image processing function. The projection system 12 is a collimator lens that brings the image lights output from the respective points on the liquid crystal display device 32 into parallel luminous fluxes.
In the liquid crystal display device 32, a first direction D1 corresponds to a direction in which a longitudinal section containing a first optical axis AX1 passing through the projection system 12 and a specific line in parallel to a third reflection surface 21c of a light guide member 21, which will be described later, extends and a second direction D2 corresponds to a direction in which a cross section containing the first optical axis AX1 and the normal line of the third reflection surface 21c extends. In other words, the first direction D1 is a direction in parallel to a line of intersection CL between a first reflection surface 21a, and the third reflection surface 21c of the light guide member 21, which will be described later, and the second direction D2 is a direction in parallel to the plane of the first reflection surface 21a and orthogonal to the line of intersection CL between the first reflection surface 21a and the third reflection surface 21c. That is, in the position of the liquid crystal display device 32, the first direction D1 corresponds to the longitudinal Y direction and the second direction D2 corresponds to the lateral X direction.
The light guide unit 20 is formed by bonding the light guide member 21 and a light transmission member 23, and forms an optical member having a flat plate shape extending in parallel to the XY plane as a whole.
Of the light guide unit 20, the light guide member 21 is a trapezoidal prism-like member in the plan view, and has the first reflection surface 21a, a second reflection surface 21b, the third reflection surface 21c, and a fourth reflection surface 21d as side surfaces. Further, the light guide member 21 has an upper surface 21e and a lower surface 21f adjacent to the first, second, third, and fourth reflection surfaces 21a, 21b, 21c, 21d and opposed to each other. Here, the first and second reflection surfaces 21a, 21b extend along the XY plane and are separated by a thickness t of the light guide member 21. Further, the third reflection surface 21c is tilted at an acute angle α equal to or less than 45° with respect to the XY plane, and the fourth reflection surface 21d is tilted at an acute angle β equal to or less than 45° with respect to the XY plane, for example. The first optical axis AX1 passing through the third reflection surface 21c and a second optical axis AX2 passing through the fourth reflection surface 21d are provided in parallel and separated at a distance D. Note that, as will be described in details, an end surface 21h is provided between the first reflection surface 21a and the third reflection surface 21c to remove an edge. The light guide member 21 has a polyhedral outer shape with seven surfaces including the end surface 21h.
The light guide member 21 guides light using total reflection by the first and second surfaces 21a, 21b. As directions perpendicular to the light guide direction, there are a direction in which the light is folded by reflection when guided and a direction in which the light is not folded by reflection when guided. In consideration of the image guided by the light guide member 21, the lateral direction in which the light is folded by plural times of reflection when guided, i.e., the confinement direction is perpendicular to the first and second reflection surfaces 21a, 21b (in parallel to the Z-axis) and corresponds to the second direction D2 of the liquid crystal display device 32 when the optical path is developed to the light source side as described below, and the longitudinal direction in which the light is not folded by reflection when guided, i.e., the free propagation direction is in parallel to the first and second reflection surfaces 21a, 21b and the third reflection surface 21c (in parallel to the Y-axis) and corresponds to the first direction D1 of the liquid crystal display device 32 when the optical path is developed to the light source side as described below.
The light guide member 21 is formed from a resin material exhibiting high light-transmissivity in the visible range. The light guide member 21 is a block-like member integrally molded by injection molding, and formed by injecting a heat polymerization resin material into a mold and thermally curing it, for example. As described above, the light guide member 21 is an integrally-molded member, but functionally, may be divided into a light-incident part 31, a light guide part 32, and a light-exiting part B3.
The light-incident part 31 is a triangular prism-like part, and has a light-incident surface IS as a part of the first reflection surface 21a and the third surface 21c opposed to the light-incident surface IS. The light-incident surface IS is a surface at the rear side or the observer's side for taking in the image light GL from the image forming unit 10, and extends to face the projection system 12 perpendicularly to its first optical axis AX1. The third reflection surface 21c is a rectangular total reflection mirror for reflecting the image light GL that has passed through the light-incident surface IS and guiding it into the light guide part B2.
Returning to
The light guide part B2 has the first reflection surface 21a and the second reflection surface 21b that respectively totally reflect the image lights that have been folded in the light-incident part B1 as two surfaces opposed to each other and extending in parallel to the XY plane. The distance between the first and second reflection surfaces 21a, 21b, i.e., the thickness t of the light guide member 21 is set to about 9 mm, for example. Here, the first reflection surface 21a is located at the rear side or the observer's side near the image forming unit 10, and the second reflection surface 21b is located at the front side or the external side far from the image forming unit 10. In this case, the first reflection surface 21a is a surface part in common with the light-incident surface IS and a light-exiting surface OS, which will be described later. The first and second reflection surfaces 21a, 21b are total reflection surfaces using refractive index differences, and provided with no reflection coatings such as mirror layers.
The total reflection in the first and second reflection surfaces 21a, 21b depends on the settings of the refractive indices of the hard coating layers 27 and may typically be caused inside of the surfaces SS of the hard coating layers 27, however, it may be caused inside of the flat surface FS.
Returning to
Returning to
The light transmission member 23 is a polygonal column member having the same refractive index as that of the main body of the light guide member 21, and has a first surface 23a, a second surface 23b, the transmission surface 23c, a first tapered surface 23f, a second tapered surface 23g, and an end surface 23j as side surfaces. The first and second surfaces 23a, 23b extend along the XY plane. Further, the transmission surface 23c is tilted with respect to the XY plane and provided to be opposed and in parallel to the fourth reflection surface 21d of the light guide member 21. The first tapered surface 23f is adjacent to the first surface 23a with an obtuse angle τ1 formed between the first surface 23a and itself, and the second tapered surface 23g is adjacent to the second surface 23b with an obtuse angle τ2 formed between the second surface 23b and itself. The light transmission member 23 is formed from a resin material exhibiting high light-transmissivity in the visible range like the light guide member 21. The light transmission member 23 is a block-like member integrally molded by injection molding, and formed by injecting a heat polymerization resin material into a mold and thermally curing it, for example. As described above, the light transmission member 23 is an integrally-molded member, but functionally, may be divided into a see-through aiding part C1 and a tapered part C2.
The see-through aiding part C1 is a trapezoidal prism-like part, and has the first surface 23a, the second surface 23b, and the transmission surface 23c, The first surface 23a is provided in parallel on the extension surface of the second reflection surface 21b provided in the light guide member 21 and located at the front side far from the eye EY of the observer, and the second surface 23b is provided in parallel on the extension surface of the first reflection surface 21a provided in the light guide member 21 and located at the rear side near the eye EY of the observer. That is, the first surface 23a and the second surface 23b are opposed to each other and extend in parallel with respect to the XY plane and the distance between the first and second surfaces 23a, 23b, i.e., the thickness of the light transmission member 23 is the same as that of the light guide member 21 and set to about 9 mm, for example. The transmission surface 23c is a rectangular transmission surface bonded to the fourth reflection surface 21d of the light guide member 21 using an adhesive. The angle formed by the first surface 23a and the transmission surface 23c is equal to the angle β formed by the first reflection surface 21a and the fourth reflection surface 21d of the light guide member 21, and the angle formed by the second surface 23b and the transmission surface 23c is equal to the angle c formed by the second reflection surface 21b and the fourth reflection surface 21d of the light guide member 21. Note that the first surface 23a and the second surface 23b may be coated with hard coating layers for prevention of damage on the surfaces and prevention of reduction of resolution of images like the first and second reflection surfaces 21a, 21b of the light guide member 21.
The see-through aiding part C1 forms a see-through part B4 in cooperation with the part at the light guide direction side (or the deeper side), i.e., at the −X side of the light guide member 21. Of the see-through aiding part C1, a wedge-shaped member 23m sandwiched between the first surface 23a and the third surface 23c forming an acute angle with each other and spreading in the −X direction is bonded to the light-exiting part B3 also having a wedge shape, and forms a center part with respect to the X direction in the plate-like see-through part B4 as a whole. That is, the first and second surfaces 23a, 23b are provided with no reflection coatings such as mirror layers, and transmit the external light GL′ at high transmittance like the light guide part B2 of the light guide member 21. Also, the transmission surface 23c can transmit the external light GL′ at high transmittance, however, because the fourth reflection surface 21d of the light guide member 21 has the half mirror layer 28, the external light GL′ passing through the transmission surface 23c or the like is reduced by 20%, for example. That is, the observer observes superimposition of the image light GL reduced to 20% and the external light GL′ reduced to 80%.
The tapered part C2 is a triangular prism-like part, and has the first tapered surface 23f, the second tapered surface 23g, and the end surface 23j sandwiched between them. The tapered part C2 is a light blocking part and sandwiched between the first tapered surface 23f and the second tapered surface 23g, and has a thickness reduced toward the deeper side in the light guide direction of the light guide member 21, i.e., the −X side. The taper angle 360°−(τ1+τ2) formed by the first tapered surface 23f and the second tapered surface 23g is set to 60° to 160°, for example. The end surface 23j is not essential, and unnecessary when the light transmission member 23 is integrated with the connection part 114 of the optical panel 110 shown in
The above described tapered part (light blocking part) C2 has a function of ejecting the light entering the light transmission member 23 from the light guide member 21 via the half mirror layer 28, which is likely to be ghost light, outside of the light guide unit 20 as will be described later.
C. Outline of Optical Paths of Image Lights
The upper image light GLa is brought into parallel luminous flux by the projection system 12, passes through the light-incident part B1, the light guide part B2, and the light-exiting part B3 of the light guide member 21 along the developed optical axis AX′, and enters the eye EY of the observer as parallel luminous flux at a tilt of an angle φ1 from the upper side. On the other hand, the lower image light GLb is brought into parallel luminous flux by the projection system 12, passes through the light-incident part B1, the light guide part B2, and the light-exiting part B3 of the light guide member 21 along the developed optical axis AX′, and enters the eye EY of the observer as parallel luminous flux at a tilt of an angle φ2 (|φ2|=|φ1|) from the lower side. The above described angles φ1, φ2 correspond to upper and lower half angles of view, and are set to 6.5°, for example.
The image light GLc from the first display point P1 on the right is brought into parallel luminous flux by the projection system 12, passes through the light-incident part B1, the light guide part 32, and the light-exiting part B3 of the light guide member 21 along the developed optical axis AX′, and enters the eye EY of the observer as parallel luminous flux at a tilt of an angle θ1 from the right side. On the other hand, the image light GLd from the second display point P2 on the left is brought into parallel luminous flux by the projection system 12, passes through the light-incident part 31, the light guide part B2, and the light-exiting part B3 of the light guide member 21 along the developed optical axis AX′, and enters the eye EY of the observer as parallel luminous flux at a tilt of an angle θ2 (|θ2|=|θ1|) from the left side. The above described angles θ1, θ2 correspond to right and left half angles of view, and are set to 10°, for example.
Note that, regarding the lateral direction of the second direction D2, the image lights GLc, GLd are folded by reflection in the light guide member 21 and the numbers of reflections are different, and the respective image lights GLc, GLd are discontinuously illustrated in the light guide member 21. Further, regarding the eye EY of the observer, the direction of view is vertically inverted compared to the case of
According to the above described configuration, the image lights GLa, GLb, GLc, GLd entering the eye EY of the observer are virtual images from infinity. With respect to the longitudinal first direction D1, the image formed on the liquid crystal display device 32 is erected and, with respect to the lateral second direction D2, the image formed on the liquid crystal display device 32 is inverted.
D. Optical Paths of Image Lights with Respect to Lateral Direction
The image lights GL11, GL12 from the first display point P1 on the right of the liquid crystal display device 32 pass through the lenses L1, L2, L3 of the projection system 12 into parallel luminous fluxes, and enter the light-incident surface IS of the light guide member 21. The image lights GL11, GL12 that have been guided into the light guide member 21 are repeatedly totally reflected at equal angles on the first and second reflection surfaces 21a, 21b, and finally output as parallel luminous fluxes from the light-exiting surface OS. Specifically, the image lights GL11, GL12 are reflected by the third reflection surface 21c of the light guide member 21 as parallel luminous fluxes, and then, enter the first reflection surface 21a of the light guide member 21 at a first reflection angle γ1, and are totally reflected (the first total reflection). Then, the image lights GL11, GL12 enter the second reflection surface 21b with the first reflection angle γ1 held and are totally reflected (the second total reflection), and then, enter the first reflection surface 21a again and are totally reflected (the third total reflection). As a result, the image lights GL11, GL12 are totally reflected by the first and second reflection surfaces 21a, 21b in a total of three times, and enter the fourth reflection surface 21d. The image lights GL11, GL12 are reflected by the fourth reflection surface 21d at the same angle as that by the third reflection surface 21c, and output from the light-exiting surface OS as parallel luminous fluxes at a tilt of the angle θ1 with respect to the second optical axis AX2 perpendicular to the light-exiting surface OS.
The image lights GL21, GL22 from the second display point P2 on the left of the liquid crystal display device 32 pass through the lenses L1, L2, L3 of the projection system 12 into parallel luminous fluxes, and enter the light-incident surface TS of the light guide member 21. The image lights GL21, GL22 that have been guided into the light guide member 21 are repeatedly totally reflected at equal angles on the first and second reflection surfaces 21a, 21b, and finally output as parallel luminous fluxes from the light-exiting surface OS. Specifically, the image lights GL21, GL22 are reflected by the third reflection surface 21c of the light guide member 21 as parallel luminous fluxes, and then, enter the first reflection surface 21a of the light guide member 21 at a second reflection angle γ2 (γ2<γ1), and are totally reflected (the first total reflection). Then, the image lights GL21, GL22 enter the second reflection surface 21b with the second reflection angle γ2 held and are totally reflected (the second total reflection), enter the first reflection surface 21a again and are totally reflected (the third total reflection), enter the second reflection surface 21b again and are totally reflected (the fourth total reflection), and enter the first reflection surface 21a again and are totally reflected (the fifth total reflection). As a result, the image lights GL21, GL22 are totally reflected by the first and second reflection surfaces 21a, 21b in a total of five times, and enter the fourth reflection surface 21d. The image lights GL21, GL22 are reflected by the fourth reflection surface 21d at the same angle as that by the third reflection surface 21c, and output from the light-exiting surface OS as parallel luminous fluxes at a tilt of the angle θ2 with respect to the second optical axis AX2 perpendicular to the light-exiting surface OS.
In
Of the liquid crystal display device 32 shown in
In the above description, the number of total reflections of the image lights GL11, GL12 output from the first partial area A10 containing the first display point P1 on the right of the liquid crystal display device 32 by the first and second reflection surfaces 21a, 21b has been three in total and the number of total reflections of the image lights GL21, GL22 output from the second partial area A20 containing the second display point P2 on the left of the liquid crystal display device 32 by the first and second reflection surfaces 21a, 21b has been five in total, however, the number of total reflections may be appropriately changed. That is, by adjustment of the outer shape of the light guide member 21 (i.e., the thickness t, the distance D, the acute angles α, β), the number of total reflections of the image lights GL11, GL12 may be five in total and the number of total reflections of the image lights GL21, GL22 may be seven in total. Further, in the above description, the numbers of total reflections of the image lights GL11, GL12, GL21, GL22 have been odd numbers, however, if the light-incident surface IS and the light-exiting surface OS are located at the opposite sides, i.e., the light guide member 21 is formed in a parallelogram shape in the plan view, the numbers of total reflections of the image lights GL11, GL12, GL21, GL22 are even numbers.
In the embodiment, in the light transmission member 23, the tapered part (light blocking part) C2 is provided at the deeper side in the light guide direction than the see-through aiding part C1, i.e., the −X side for reducing the thickness at the deeper side, and the unwanted light HL may be output to the outside of the tapered part C2. Specifically, the tapered part C2 has a shape narrower toward the deeper side, i.e., the −X side, and the reflection angle of the unwanted light HL that has passed through the fourth reflection surface 21d provided with the half mirror layer 28 and the transmission surface 23c gradually becomes smaller at each time when reflected by one of the tapered surfaces 23f, 23g. As a result, the reflection angle of the unwanted light HL gradually becomes smaller within the tapered part C2 and no longer satisfies the total reflection condition, and the light passes through one of the tapered surfaces 23f, 23g in the position out of the see-through part B4 opposed to the eye of the observer and ejected to the outside. As described above, the tapered part C2 has a function of preventing the unwanted light HL from being ghost light GG or reaching the eye Y.
Note that, as long as the tapered part C2 has the shape narrower toward the deeper side, i.e., the −X side, one of the first and second tapered surfaces 23f, 23g may be omitted. That is, if the first tapered surface 23f is omitted, the extended first surface 23a and the second tapered surface 23g may form the tapered shape narrower toward the deeper side, i.e., the −X side, and unwanted light HL maybe ejected to the outside of the light transmission member 23 by the tapered shape. Further, if the second tapered surface 23g is omitted, the extended second surface 23b and the first tapered surface 23f may form the tapered shape narrower toward the deeper side, i.e., the −X side, and unwanted light HL may be ejected to the outside of the light transmission member 23 by the tapered shape.
E. Modified Examples
In the modified example, the unwanted light HL as an unwanted component of the image light GL that has passed through the fourth reflection surface 21d provided with the half mirror layer 28 and the transmission surface 23c enters one of the third and fourth surfaces 223f, 223g provided in the light diffusion part (light blocking part) C3 to be diffused, and is not returned to the light guide member 21 side.
In the modified example, the unwanted light HL as an unwanted component of the image light GL that has passed through the fourth reflection surface 21d provided with the half mirror layer 28 and the transmission surface 23c enters one of the third and fourth surfaces 323f, 323g provided in the light absorption part (light blocking part) C4 and absorbed by the light-absorbing layer 29, and is not returned to the light guide member 21 side.
F. Others
in the virtual image display system 100 of the embodiment that has been explained, the image light GL reflected by the third reflection surface 21c of the light-incident part B1 is propagated while being totally reflected by the first and second reflection surfaces 21a, 21b of the light guide part, and reflected by the fourth reflection surface 21d of the light-exiting part B3 and enters the eye EY of the observer as a virtual image. In this regard, the numbers of reflections in the light guide part of the first image lights GL11, GL12 output from the first partial area A10 containing the first display point P1 of the image display unit 11 and the numbers of reflections in the light guide part B2 of the second image lights GL21, GL22 output from the second partial area A20 containing the second display point P2 of the image display unit 11 are different, and thus, the angular width of the output angle of the image light GL output from the light-exiting part B3 may be taken wider. That is, the image lights GL from the different partial areas A10, A20 in the image display unit 11 may be taken in at a wider angle of view, and the display size of the virtual image observed through the light-exiting part B3 may be secured larger. As described above, according to the structure of extracting image lights GL at different numbers of reflection, the light-exiting part B3 may be made larger to cover the eye without making the light guide part B2 so much thicker, and it is not necessary to bring the light-exiting part B3 closer to the eye for eye division, and the eye ring diameter may be secured larger, and good see-through observation may be realized.
Further, in the virtual image display system 100 of the embodiment, the thickness of the tapered part C2 provided at the deeper side (the −X side) in the light guide direction of the light transmission member 23 is smaller toward the deeper side, and the reflection angle of the ghost light that has passed through the fourth reflection surface 21d provided with the half mirror layer 28 and reached the light transmission member 23 gradually becomes smaller within the tapered part C2 and no longer satisfies the total reflection condition, and the light is not returned to the light guide member 21, but ejected to the outside in the position diverging from the eye EY of the observer. Alternately, also the light diffusion part C3 and the light absorption part C4 may prevent the ghost light from being returned to the light guide member 21. That is, the tapered part C2, the light dif fusion part C3, and the light absorption part C4 may prevent the ghost light from reaching the eye and good see-through observation can be realized.
The invention has been explained according to the embodiments, however, the invention is not limited to the above described embodiments and may be implemented in various forms without departing from the scope of the invention. For example, the following modifications may be made.
In the embodiments, priority has been given to seeing through by setting the reflectance of the half mirror layer 28 provided in the fourth reflection surface 21d of the light guide member 21 to 20%, however, priority may be given to image light by setting the reflectance of the half mirror layer 28 to 50% or higher. Note that the half mirror layer 28 may not necessarily be formed on the entire surface of the fourth reflection surface 21d, and may be formed only in a partial necessary part. Regarding the half mirror layer 28, the half mirror layer 28 maybe formed on the transmission surface 23c of the light transmission member 23, and, in this case, the half mirror layer 28 may substantially function as the fourth reflection surface 21d.
In the embodiments, the first and second surfaces 23a, 23b have been provided in the see-through aiding part C1 of the light transmission member 23, however, the second surface 23b may be omitted. Also, in this case, the second tapered surface 23g may be provided adjacently to the transmission surface 23c.
In the embodiments, in the light transmission member 23, the tapered part C2, the light diffusion part C3, or the light absorption part C4 has been provided entirely in the longitudinal Y direction, however, the tapered part C2, the light diffusion part C3, or the light absorption part C4 may be provided locally in the part in the longitudinal direction, and, also, in this case, generation of ghost light may be suppressed.
In the case where the tapered part C2 is provided in the light transmission member 23, it is desirable to let the ghost light travel to the front side without the eye EY. For the purpose, is it desirable to appropriately adjust the angle τ1 with respect to the first surface 23a of the first tapered surface 23f and the angle τ2 with respect to the second surface 23b of the second tapered surface 23g.
In the case where the tapered part C2 is provided in the light transmission member 23, it is not necessary to make the taper in the uniform one step, and return light may be prevented by parts having a taper in multiple steps or a taper in a curved surface.
In the case where the tapered part C2 is provided in the light transmission member 23, for example, the light diffusion part C3 or the light absorption part C4 may be additionally provided. In this case, the tapered surfaces 23f, 23g are roughened or light-absorbing paint may be applied to the tapered surfaces 23f, 23g.
The shape of the light transmission member 23 is not limited to the shape formed by extending the light guide member 21 laterally, i.e., in the −X direction, but may include a part formed by expanding the light guide member 21 from upper side and the lower side.
In the embodiments, directionality has not been particularly provided to the illumination light SL from the illumination device 31, however, directionality in response to the position of the liquid crystal display device 32 may be provided to the illumination light SL. Thereby, the liquid crystal display device 32 may be efficiently illuminated and brightness irregularities depending on the position of the image light GL may be reduced.
In the embodiments, the display brightness of the liquid crystal display device 32 has not particularly been adjusted, however, display brightness may be adjusted in response to the range and overlapping of the projection images IM1, IM2 as shown in
In the embodiments, the transmissive liquid crystal display device 32 or the like has been used as the image display unit 11, however, various devices other than the transmissive liquid crystal display device 32 may be used as the image display unit 11. For example, a configuration using a reflective liquid crystal display device may be employed, or a digital micromirror device, or the like may be employed in place of the liquid crystal display device 32. Further, a self-emitting device represented by an LED array, an OLED (organic EL), or the like may be used as the image display unit 11.
In the virtual image display system 100 of the embodiment, the image forming units 10 and light guide units 20 have been provided in pairs in correspondence to the right eye and the left eye, however, the image forming unit 10 and light guide unit 20 may be provided only for either of the right eye or the left eye for observation by a single eye.
In the embodiments, 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 have been in parallel, however, the optical axes AX1, AX2 may be made not in parallel.
In the above description, the specific explanation has been made with the virtual image display system 100 as the head-mounted display, however, the virtual image display system 100 may be altered to a head-up display.
In the above description, in the first and second reflection surfaces 21a, 21b, the image lights have been totally reflected and guided by interfaces between air and themselves without mirrors, half-mirrors, or the like formed on the surfaces, however, the total reflection in the invention includes reflection by mirror coatings or half-mirror films formed on the entire or parts of the first and second reflection surfaces 21a, 21b. For example, the case where the incident angle of the image light satisfies the total reflection condition and mirror coatings or the like are formed on the entire or parts of the first and second reflection surfaces 21a, 21b and all of the image light is substantially reflected may be included. Further, as long as image light with sufficient brightness is obtained, the entire or parts of the first and second reflection surfaces 21a, 21b may be coated with mirrors with some transmissivity. Note that the entire or parts of the first surface 23a and the second surface 23b of the light transmission member 23 may be coated with mirrors with some transmissivity.
In the above description, the light guide member 21 extends in the lateral direction in which the eyes EY are arranged, however, the light guide member 21 may extend in the longitudinal direction. In this case, the optical panels 110 are arranged in parallel not in series but side by side.
The entire disclosure of Japanese Patent Application No. 2011-030542, filed Feb. 16, 2011 is expressly incorporated by reference herein.
Takeda, Takashi, Komatsu, Akira, Takagi, Masayuki, Totani, Takahiro, Miyao, Toshiaki
Patent | Priority | Assignee | Title |
Patent | Priority | Assignee | Title |
6219188, | Feb 26 1998 | Canon Kabushiki Kaisha | Observation optical system |
7944616, | Aug 21 2008 | Sony Corporation | Head-mounted display |
8052308, | Apr 18 2007 | Seiko Epson Corporation | Light source having wavelength converter and wavelength separating member for reflecting converted light |
20010010598, | |||
20060087755, | |||
20070047091, | |||
20070058261, | |||
20070091445, | |||
20080239422, | |||
20100103078, | |||
20100245211, | |||
20110181960, | |||
20120200935, | |||
20120200936, | |||
20120200937, | |||
20120200938, | |||
JP11249067, | |||
JP2006003879, | |||
JP2007129550, | |||
JP2008052096, | |||
JP2008122511, | |||
JP2008165016, | |||
JP2008268873, | |||
JP2008535001, | |||
JP2010224473, | |||
JP2010230716, | |||
JP2010276914, | |||
WO2010041578, |
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