Optical device for producing an image outside of a fiber optic panel

Abstract

Optical device (10) comprising: a light guide plate (70) configured to guide light in a plane parallel to an emission surface (71); and several deflectors (30) configured to deflect light guided therefrom by the light guide plate (70), causing light forming an image in a space outside the light guide plate (70) to exit the emission surface (71); wherein: each deflector (30) of the several deflectors (30) causes the light to exit the emission surface (71) in a direction that converges on a single convergence point or line of convergence in the space, or to radiate from a single convergence point or line of convergence in the space;and the convergence point or convergence line is distinguishable from one another among the several deflectors (30) with a grouping of several of the convergence points or convergence lines that form the image in space; each deflector (30) of the several deflectors (30) is arranged such that one of the light rays in the light emitted from the emission surface (71) passes through a specific observation position (380) in space via the deflector (30);at least one of the deflectors (30) among the several deflectors (30) is arranged such that, if a first line connects an edge of the deflector (30) and the convergence point or convergence line, and a second line connects the convergence point or convergence line to the observation position (30), the first line is arranged between the point where the second line or an extension thereof crosses the optical fiber plate (70) and one edge (301) of the deflector, such that the first line and the second line do not form an angle greater than a predetermined angle in a plane that is orthogonal to the direction along which light is guided through the optical fiber plate (70);at least one of the deflectors (30) of the multiple deflectors (30) comprises a first segment (610) near one edge and a second segment (620) near another edge, wherein the first segment (610) and the second segment (620) are located about a position corresponding to the optical axis of light that converges to the point or line of convergence in a plane orthogonal to the direction along which light is guided through or emitted from the light guide plate (70); and the light emitted by the first segment (610) and the light emitted by the second segment (620) are asymmetric about the optical axis.

Description

FIELD OF THE INVENTIONThe present invention relates to an optical apparatus and an optical system.PRIOR ARTA display device stereoscopically displaying a two-dimensional image is known from, for example, Japanese Patent Publication JP 2001-255 493 A. More specifically, the display device is composed of a display unit provided with an image display surface which displays a two-dimensional image, and a microlens array separated from the image display surface. The light emitted from the image display surface forms an image on an image forming plane disposed on the side of the display unit opposite to the microlens array, and thus stereoscopically displays the two-dimensional image.Moreover, the patent publication DE 11 2015 004 586 T5 discloses an optical device having a light guide plate which guides lights within a surface parallel to an output surface, and having a plurality of light converging sections on which the lights guided by the light guide plate are incident. Each of the plurality of light condensing sections has an optical surface that allows an emitted light to be emitted from the emitting surface in a direction in which the emitted light is to be condensed at a single convergence point or line in space or diverge from a single convergence point or line in space. The plurality of light condensing sections are each formed along a predetermined line within the surface parallel to the output surface, and the convergence points or the convergence lines are different from each other among the plurality of light condensing sections. Thus, an image can be formed by a collection of a plurality of the convergence points or the convergence lines in space.Further prior art is formed by the patent publication DE 11 2017 003 581 T5.TECHNICAL PROBLEMLight beams for forming an image outside a light guide plate may be provided via a plurality of deflectors provided in the light guide plate for deflecting light in the light guide. Here, the manufacturing cost of the light guide plate increases with the size of the surface area of the light guide plate filled with the deflectors. The ability of the light guide plate to transmit light also decreases with the size of the surface area on the light guide plate filled with the deflectors. In view of the above problems, the present invention is defined by the independent claims. Preferred embodiments are the subject matter of the dependent claims.SUMMARYA first embodiment provides an optical device. The optical device may include a light guide plate configured to guide light in a plane parallel to an emission surface. The optical device may include a plurality of deflectors configured to deflect light directed thereto from the light guide plate, thereby causing light forming an image in a space outside the light guide plate to exit the emission surface. Each deflector of the plurality of deflectors may cause the light to exit the emission surface in a direction that substantially converges on a single point of convergence or a line of convergence in the space or to substantially radiate from a single point of convergence or a line of convergence in the space. The convergence point or the convergence line may be different from each other among the plurality of deflectors with grouping of a plurality of the convergence points or the convergence lines forming the image in the space. Each deflector of the plurality of deflectors may be configured such that one of the light beams in the light emitted from the emission surface passes through a certain observation position in the space via the deflector. At least one of the deflectors among the plurality of deflectors may be configured such that, when a first line connects an edge of the deflector and the convergence point or the convergence line and a second line connects the convergence point or the convergence line to the observation position, the first line is disposed between the location where the second line or an extension thereof crosses the light guide plate and the one edge of the deflector such that the first line and the second line do not form greater than a predetermined angle in a plane orthogonal to the direction along which light is guided by the light guide plate.Each deflector of the plurality of deflectors may be configured such that, when a third line connects another edge of the at least one deflector and the convergence point or line, the third line is disposed between the location where the second line or an extension thereof crosses the light guide plate and the other edge of the deflector such that the third line and the second line do not form greater than a predetermined angle in a plane that is orthogonal to the direction along which light is guided by the light guide plate.Each deflector of the plurality of deflectors may be formed along a predetermined line in a plane parallel to the emission surface.At least one of the deflectors of the plurality of deflectors may include a first segment near one edge and the second segment near the other edge, the first segment and the second segment being located around a position corresponding to the optical axis of the light converging toward or radiating from the converging point or the converging line in a plane orthogonal to the direction along which light is guided by the light guide plate; and the light emitted from the first segment and the light emitted from the second segment may be asymmetric around the optical axis.At least one of the deflectors of the plurality of deflectors includes a first segment near one edge and the second segment near the other edge, the first segment and the second segment being disposed around a position corresponding to the optical axis of light converging toward or radiating from the converging point or the converging line in a plane orthogonal to the direction along which light is guided by the light guide plate; and the length of the first segment in a direction parallel to the emission surface and the length of the second segment in a direction parallel to the emission surface in a plane orthogonal to the direction along which light is guided by the light guide plate are asymmetric.The light guided by the light guide plate may be substantially parallel in a plane parallel to the emission surface; the first segment and the second segment may each include a plurality of deflection surfaces configured to deflect light incident thereon; and the plurality of deflection surfaces in the first segment and the plurality of deflection surfaces in the second segment may be asymmetrically aligned around a position corresponding to a line connecting the convergence point or the convergence line and the observation position.The degree of asymmetry for a deflector disposed near the edge of the light guide plate may be greater than the degree of asymmetry for a deflector disposed near the center of the light guide plate.A second non-claimed embodiment provides an optical device.The optical device may include a light guide plate configured to guide light in a plane parallel to an emission surface. The optical device may include a plurality of deflectors arranged two-dimensionally in a plane parallel to the emission surface, and each deflector is configured to deflect light guided thereto through the light guide plate, thereby causing the light forming an image in a space to exit the emission surface. Each deflector of the plurality of deflectors may be configured to spread the light incident thereon into light having an intensity distribution corresponding to the image in a direction orthogonal to the light guiding direction of the light guide plate in a plane parallel to the emission surface, and cause the emission surface to output the light such that grouping of the light from a plurality of deflectors arranged along a direction orthogonal to the light guiding direction thereby forms the light emitted from the image. Each deflector of the plurality of deflectors may be configured such that one of the light beams in the light emitted from the emission surface passes through a certain observation position in the space via the deflector.A third embodiment provides an optical device. The optical device may include a light guide plate configured to guide light in a plane parallel to an emission surface. The optical device may include a plurality of deflectors arranged two-dimensionally in a plane parallel to the emission surface, and each deflector is configured to deflect light guided thereto through the light guide plate, thereby causing the light forming an image in a space to exit the emission surface. Each deflector of the plurality of deflectors may be configured to two-dimensionally spread the light incident thereon into light having an intensity distribution corresponding to the image and cause the emission surface to output the light such that grouping of the light from three or more deflectors disposed on different straight lines thereby forms the light emitted from the image, and each deflector of the plurality of deflectors may be configured such that one of the light beams in the light emitted from the emission surface via the deflector passes through a specific observation position in the space.One deflector among the plurality of deflectors may be provided on a line or an extension thereof connecting an arbitrary point in the image to the observation position.Each deflector of the plurality of deflectors may include one or more groups of deflection surfaces that are inclined relative to the emission surface at the outer surface or at the inner side of the light guide plate and configured to reflect, break, or diffract light directed thereto from the light guide plate.At least one of the deflection surfaces may be configured to include a plurality of flat or curved surfaces oriented in different directions.At least one of the deflection surfaces may be elongated, bent, or curved in a direction orthogonal to the light guiding direction of the light guide plate when the deflection surface is projected on a surface parallel to the emission surface.The optical device may further include a light source configured to emit light guided by the light guide plate.It is noted that the summary above does not list all features of the present invention; and sub-combinations of these sets of features also fall within the scope of the invention.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic view of a display device 10 according to a first embodiment together with a three-dimensional image projected into a space; FIG. 2 illustrates a reflection surface 31 aincluded in a deflector 30 a; a reflection surface 31 bincluded in a deflector 30 b; and a reflection surface 31 cincluded in a deflector 30 c; FIG. 3 schematically illustrates a cross section of the display device 10 in the xz plane; FIG. 4 illustrates a cross section of the display device 10 in the xz plane when an additional observation position 382 is defined; FIG. 5 illustrates a cross section of the display device 10 in the xz plane when the observation position is limited to a specific range in which an image can be perceived; FIG. 6 is an exploded view of a portion of FIG. 3 ; FIG. 7 shows a display device 700 as a comparative example of the display device 10; FIG. 8 illustrates a cross section of a display device 10A as a comparative example of the display device 10; FIG. 9 shows a display device 900 as a comparative example of the display device 10A; FIG. 10 illustrates a cross section of a display device 10B as a comparative example of the display device 10; FIGS. 11A and 11B are schematic views of a deflector 130 and a deflector 132 as comparative examples of the deflector 30; FIG. 12 is a schematic view of a display device 210 according to a second non-claimed embodiment together with an image projected into a space; FIG. 13 schematically illustrates a cross section of the display device 210 in the yz plane; FIG. 14 is a schematic view illustrating an example of an optical element 231 including a deflector 230; FIG. 15 schematically illustrates a deflector 230 providing light traveling towards a particular observation position; FIG. 16 illustrates the relationship among a reflection surface 40 a, a reflection surface 41 b, and an observation position 380. FIG. 17 is a schematic view of a deflector 330 as a comparative example of the deflector 230; FIG. 18 is a schematic perspective view of a deflector 230A as a comparative example of the deflector 230; FIG. 19 serves to describe how a deflector 230G is formed as a comparison with the deflector 230A; FIGS. 20A and 20B are for describing how a deflector 230G is formed as a comparison with the deflector 230A; FIGS. 21A, 21B, and 21C schematically illustrate additional examples of the shape of an optical element 231; FIGS. 22A, 22B, and 22C schematically illustrate examples of distributing the optical elements 231 in the xy plane; FIGS. 23A and 23B schematically illustrate additional examples of the shape of the reflection surface of an optical element 231; FIGS. 24A and 24B schematically illustrate various examples of the shape of the reflection surface of an optical element 231; and FIG. 25 is a schematic view of an image 16 formed by a display device 2010 as a comparative example of the display device 10.DETAILED DESCRIPTIONFIG. 1 is a schematic view of a display device 10 according to a first embodiment together with a three-dimensional image projected into a space. The drawings used to describe the embodiment are general and schematic to provide a clear explanation. In some cases, the drawings are not drawn to scale. The drawings including a three-dimensional image are not necessarily drawn from the view of a viewer and may be drawn from another perspective to ensure that the location of the image in a space is easily understood.The display device 10 is provided with a light guide plate 70 and a light source 20. The light guide plate 70 is a transparent resin material having a relatively high refractive index. The light guide plate 70 may be made of, for example, a polycarbonate resin (PC), a polymethyl methacrylate resin (PMMA), glass, or the like. The light guide plate 70 is an example of the optical device. The display device 10 is an example of an optical system.The light guide plate 70 includes an emission surface 71 that outputs light. The emitting surface 71 functions as the display surface of the display device 10. The image 6 is a three-dimensional image perceived in a space by the user. Note that the term "three-dimensional image" refers to an image that appears to be at a position different from the emission surface 71 of the light guide plate 70. The term "three-dimensional image" also includes a two-dimensional image perceived at a location away from the emission surface 71, for example. In other words, the term "three-dimensional image" refers not only to an image perceived as having a fixed shape, but also includes an image in two-dimensional shape perceived at a location other than on the display surface of the display device 10.The light guide plate 70 includes a back surface 72 on the opposite side of the emission surface 71. the emission surface 71 is one main surface of the light guide plate 70, and the back surface 72 is the other main surface. The light guide plate 70 also includes edges on the four sides thereof, i.e., a first edge 73, a second edge 74, a third edge 75, and a fourth edge 76. the first edge 73 is the incident end surface of the light guide plate 70. a light source 20 is provided on the first edge 73 where light from the light source 20 enters the light guide plate 70 from the first edge 73. The second edge 74 is opposite the first edge 73. The fourth edge 76 is opposite the third edge 75.A rectangular coordinate system, and in particular the x-axis, y-axis, and z-axis right-handed system, is used at some points to describe the embodiments. Here, the z-axis direction is a direction perpendicular to the emission surface 71. the positive z-axis direction is defined as the direction from the back surface 72 to the emission surface 71. The y-axis direction is a direction perpendicular to the first edge 73. the positive y-axis direction is defined as the direction from the first edge 73 to the second edge 74. The direction of the x-axis is the direction perpendicular to the third edge 75 and the fourth edge 76; and the direction of the positive x-axis is defined as the direction from the third edge 75 to the fourth edge 76. In order to avoid redundancy in the description, planes parallel to the planes xy, yz, and xz are sometimes referred to as the xy plane, yz plane, and xz plane, respectively.The light source 20 may be an LED light source. The optical axis of the light source 20 is substantially parallel to the y-axis. Light from the light source 20 enters via the first edge 73. Light from the light source 20 entering via the first edge 73 is totally reflected between the emitting surface 71 and the back surface 72, and passes through the light guide plate while propagating in a plane in the light guide plate 70. The center of the light guided by the light guide plate 70 is substantially parallel to the y-axis. Thus, the light guide plate 70 guides light from the light source 20 such that the light propagates in a plane parallel to the emission surface 71 in a planar manner. A light beam transmitted through the light guide plate 70 passes through positions in the light guide plate 70 at a propagation angle smaller than a predetermined value at each of the positions. More specifically, the light guided by the light guide plate 70 forms a spread angle smaller than a predetermined value around a direction connecting a position in the light guide plate 70 and the light source 20. That is, a light beam passing through a position in the light guide plate 70 forms a spread angle in the xy plane with a spread angle formed around a direction connecting the position in the light guide plate 70 and the light source 20 that is smaller than a predetermined value. In this specification, the propagation of a light beam passing through a point in or outside the light guide plate is considered to be the propagation of light when the light beam radiates from this point.A plurality of deflectors 30 are provided on the rear surface 72 of the light guide plate 70; the plurality of deflectors 30 include a deflector 30 a, a deflector 30 b, a deflector 30 c, and a deflector 30 d. The deflectors 30 are largely formed sequentially along the direction of the x-axis. Light entering the first edge 73 from the light source 20 is totally reflected between the emitting surface 71 and the rear surface 72 while being guided by the light guide plate 70, and enters the deflectors 30 at each position of a deflector 30 along the x-axis direction.Here, the light guided by the light guide plate 70 will be described as if no component propagates along the yz plane. The deflectors 30 cause the light entering each position of a deflector 30 to substantially converge at a fixed point corresponding to the deflector 30. In particular, FIG. 1 illustrates a portion of deflectors 30: deflectors 30 a, deflectors 30 b, deflectors 30 c, and deflectors 30 d. Fig. 1 shows the light beams emitted from the deflector 30a, the deflector 30b, the deflector 30c and the deflector 30d convergingly.More specifically, the deflector 30a corresponds to a fixed point PA in the image 6. Therefore, the optical wavefront from the deflector 30 aappears as an optical wavefront radiating from the fixed point PA. Similarly, the deflector 30 bcorresponds to the fixed point PBin the image 6, and light beams from positions of the deflector 30 bconverge at the fixed point PB. The deflector 30 cfurther corresponds to the fixed point PC in the image 6, and light beams from positions of the deflector 30 cconverge at the fixed point PC. The deflector 30 dfurther corresponds to the fixed point PD in the image 6, and light beams from positions of the deflector 30 dconverge at the fixed point PD. Thus, deflectors 30 cause the light entering each position of a deflector 30 to substantially converge at a fixed point corresponding to deflector 30. Thus, one of the deflectors 30 may represent an optical wavefront that appears as light emitted from a corresponding fixed point. The fixed points correspond to different deflectors 30; and grouping of multiple fixed points corresponding to deflectors 30 produces an image 6 that can be perceived in a space.In this embodiment, the deflectors 30 include a plurality of reflection surfaces that are formed mostly sequentially along the direction of the x-axis. A reflection surface is an example of a deflection surface. FIG. 2 illustrates one of the plurality of reflection surfaces included in the deflector 30 a, i.e., a reflection surface 31 a; one of the plurality of reflection surfaces included in the deflector 30 b, i.e., a reflection surface 31 b; and one of the plurality of reflection surfaces included in the deflector 30 c, i.e., a reflection surface 31 c. The light guided by the light guide plate 70 and incident on the reflection surface 31 ais reflected by the reflection surface 31 a, passes through the emission surface 71, and travels toward PA. The light guided by the light guide plate 70 and incident on the reflection surface 31 bis reflected by the reflection surface 31 b, passes through the emission surface 71, and passes toward PB. The light guided by the light guide plate 70 and incident on the reflection surface 31 cis reflected by the reflection surface 31 c, passes through the emission surface 71, and travels toward the PC.The reflecting surfaces of a single deflector 30 are oriented in mutually different directions and reflect light incident on the deflector 30 toward a single fixed point corresponding thereto. Thus, the light reflected from the reflecting surfaces of the deflector 30 converges at a single fixed point corresponding to the deflector 30. For example, the respective multiple light beams reflected from the multiple reflection surfaces in the deflector 30 aconverge at the specified point PA. The respective multiple light beams reflected from the multiple reflection surfaces in the deflector 30 balso converge at the specified point PB. The respective multiple light beams reflected from the multiple reflection surfaces in the deflector 30 cfurther converge at the fixed point PC. The respective multiple light beams reflected from the multiple reflection surfaces in the deflector 30 dfurther converge at the specified point PD.Thus, as described above, the light guided by the light guide plate 70 forms a propagation angle in the xy plane that is smaller than a predetermined value around a direction connecting the position in the light guide plate 70 and the light source 20. In other words, the light guided by the light guide plate 70 propagates in the xy plane around a direction connecting the position in the light guide plate 70 and the light source 20. A deflector 30 may be provided at a position away from the light source 20; in this case, the light guided by the light guide plate 70 travels with approximately the y-axis direction as the center from the position of the deflector 30, and propagates substantially in the xy-plane. Accordingly, light from the deflector 30 aconverges substantially at a single fixed point in, for example, a plane parallel to the xz plane including the fixed point PA.As illustrated in FIG. 1, the deflector 30 ais formed along a line 190 a; the deflector 30 bis formed along a line 190 b; and the deflector 30 cis formed along a line 190 c. Here, the line 190 a, the line 190 b, and the line 190 care straight lines substantially parallel to the x-axis. Each other deflector 30 is similarly formed in a sequential fashion for the most part along straight lines substantially parallel to the x-axis.In this manner, the deflectors 30 are each formed along a predetermined line in a plane parallel to the emission surface 71. Light guided by the light guide plate 70 is incident on the deflectors 30, and the deflectors 30 may cause emission light to exit from the emission surface 71 in a direction that substantially converges to a single convergence point in a space. Note that the predetermined point for forming an image may be provided near the back surface 72 of the light guide plate 70. In this case, a deflector 30 corresponding to the specified point near the rear surface 72 may cause light to exit from the emission surface 71 in a direction in which the light radiates from the specified point. For example, a deflector 30 corresponding to a specified point near the back surface 72 may include a reflection surface that causes emission light to exit from the emission surface 71 in a direction that causes the light to be substantially radiated from a single point of convergence in a space.Note that the light guided by the light guide plate 70 may not include a component propagating in a direction coincident with the yz plane; in this case, light from the deflector 30 substantially converges at a fixed point as described above. On the other hand, when the light guided by the light guide plate 70 includes a component propagating in a direction coincident with the yz plane, the light reflected by the reflection surface of the deflector 30 substantially converges on a converging line parallel to the yz plane and parallel to the emission surface. For example, the light from a deflector 30 asubstantially converges on a line including [the fixed point] PA and parallel to the yz plane and parallel to the emission surface 71. The reflection surface on the deflector 30 generates emission light that exits from the emission surface 71 in a direction such that the light is radiated to a space for the most part from a single convergence line, similar to when the set point is close to the back surface 72 of the light guide plate 70. However, the viewer can see only the portion of the light which converges on or radiates from the converging line and which travels toward an eye of the viewer; this thus allows the viewer to perceive the image 6.FIG. 3 schematically illustrates a cross section of the display device 10 in the xz plane; the region through which the deflector 30 aand the deflector 30 dare respectively formed will be described with reference to FIG. 3. Here, the range by which the deflector 30 is formed refers to the maximum range in which the reflection surface 31 is formed in the x-axis direction. For example, in FIG. 3, the plurality of reflection surfaces are provided on the deflector 30 abetween a first edge 201 and a second edge 203 of the deflector 30 a. Note that FIG. 3 shows the light beams emitted from the deflector 30 and an observation position 380. FIG. 3 shows a projection of the light beams and the observation position 380 onto the xy plane.FIG. 3 shows a straight line 212 passing through the fixed point PA and the observation position 380; FIG. 3 also shows a straight line 211 passing through the fixed point PA and the first edge 201 of the deflector 30 a; the line 211 and the line 212 form an angle θ 2. FIG. 3 also shows a straight line 213 passing through the fixed point PA and a second edge 203 of the deflector 30 a; the line 213 and the line 212 form an angle θ 2.Accordingly, the reflection surfaces 31 are formed on the deflector 30 asuch that a line connecting a reflection surface 31 and the fixed point PA forms an angle with the line 212 that is not greater than the angle θ 2. Therefore, light from the fixed point PA passes through a certain area with the observation position 380 as the center. Note that the angle θ 2 is a predetermined angle. The angle θ2is defined by the design; the angle θ2may also be an upper limit defined by the design.Thus, the deflector 30 ais configured to cause light to exit from the emission surface 71 such that one of the light beams in the light exiting from the emission surface 71 via the deflector 30 apass through a certain observation position 380 in a space outside the light guide plate 70. The deflector 30 ais configured such that the light beams in the light emitted thereby pass through a specific region including the observation position 380.FIG. 3 shows L 312 which is a straight line passing through the set point PD and the observation position 380; L 311 is a straight line passing through the set point PD and a first edge 301 of the deflector 30 d; L 311 and L 312 form an angle θ 3. L 313 is a straight line passing through the fixed point PD and a second edge 301 of the deflector 30 d; L 313 and L 312 form an angle θ 3.Accordingly, the reflection surfaces 31 are formed on the deflector 30 dsuch that a line connecting a reflection surface 31 and the fixed point PD forms an angle with the L 312 that is not greater than the angle θ 3. Therefore, light from the point PD passes through a certain range with the observation position 380 as the center. Note that the angle θ 3 is a predetermined angle. The angle θ3is defined by the design; the angle θ3may also be an upper limit defined by the design.Thus, the deflector 30 dis configured to cause light to exit from the emission surface 71 such that one of the light beams in the light exiting from the emission surface 71 via the deflector 30 dpass through a certain observation position 380 in a space outside the light guide plate 70. The deflector 30 dis configured such that the light beams in the light emitted thereby pass through a predetermined range including the observation position 380.The other deflectors 30 in the light guide plate 70 are configured identically to the deflector 30 aand the deflector 30 d. That is, each deflector 30 is configured to cause light to exit from the emission surface 71 such that one of the light beams in the light exiting from the emission surface 71 via the deflector passes through a certain observation position 380 in a space outside the light guide plate 70. Each of the deflectors 30 is configured such that the light beams in light emitted thereby pass through a predetermined range including the observation position 380. Thus, a viewer can see the entire image 6 without any portion of the image 6 appearing to be missing when the viewer's eye is in a particular area containing the observation position 380.Note that the observation position 380 may be set at a position predicted to be the center between both eyes of the viewer when the viewer uses the display device 10. The observation position 380 may also be set on a line parallel to the xy plane at a position predicted to be the center between both eyes of the viewer when the viewer uses the display device 10. For example, the position of both eyes of the player of a game machine is generally defined when the display device 10 is used in a game machine. Setting the deflectors 30 according to the position of an eye of the observer as described above is particularly advantageous when the observation position of the observer can be predicted.The distance from the emission surface 71 to the observation position 380 may be about 50 cm. The distance from the emission surface 71 to the observation position 380 may be about 30 cm to 1 m. Thus, the deflectors 30 are preferably configured according to the position of the viewer's eyes, as described above, when it is predicted that the viewer's eyes will be relatively close to the emission surface 71. A constant direction of emission for all deflectors 30 increases the likelihood that some light will not reach the viewer's eyes when the viewer's eyes are relatively close to the emission surface 71.FIG. 4 illustrates a cross section of the display device 10 in the xz plane when an additional observation position 382 is defined. As illustrated in FIG. 4, the edge 203 of the deflector 30 ais positioned such that a straight line passing through the fixed point PA and the edge 203 forms an angle θ 2 with a straight line passing through the fixed point PA and the observation position 382. The edge 303 of the deflector 30 dis positioned such that a straight line passing through the set point PD and the edge 303 forms an angle θ 3 with a straight line passing through the set point PD and the observation position 382.Thus, the deflectors 30 are configured in the light guide plate 70 to cause light to exit the emission surface 71 such that one of the light beams in the light exiting from the emission surface 71 via the deflectors 30 passes through a certain observation position 380 and observation position 382 in a space outside the light guide plate 70. Each of the deflectors 30 is configured such that the light beams in light emitted thereby pass through a specific range including the observation position 380 and the observation position 382. Thus, a viewer can see the entire image 6 without any portion of the image 6 appearing to be missing when the viewer's eye is in the aforementioned particular area.As described with reference to FIGS. 3 and 4, the deflectors 30 are configured such that light from the deflectors 30 passes through a specific region including a specific observation position. It is therefore possible to limit the range generated by the deflectors 30. Therefore, it is possible to reduce the surface area on the light guide plate 70 filled with the deflectors 30. Consequently, it is possible to reduce the manufacturing cost of the display device 10. For example, the machining cost that arises when the back surface 72 is machined to form the deflectors 30 can be reduced. The ability of the light guide plate to transmit light also increases because less of the surface area on the light guide plate can be filled with deflectors 30.Note that a single observation position 380 has been described with reference to FIG. 3 ; further, two observation positions, the observation position 380 and the observation position 382 have been described with reference to FIG. 4 ; however, the number of observation positions is not limited to one or two. There may be three or more observation positions.FIG. 5 illustrates a cross section of the display device 10 in the xz plane when the observation position is limited to a specific range in which an image can be perceived. The line 500 passes through the observation position 380 and is parallel to the xy plane. The point 501 on the line 500 is located at an accurately predetermined distance from the observation position 380 in the direction of the negative x-axis. The point 502 on the line 500 is located at an exactly predetermined distance from the observation position 380 in the direction of the positive x-axis. Here, the image may be perceived only at an observation position along the line 500. That is, it is assumed that an eye of a viewer exists along the line 500.The edge 201 of the deflector 30a is where the extension of a line connecting the point 502 and the fixed point PA crosses the light guide plate 70. The edge 203 of the deflector 30a is where the extension of a line connecting the point 501 and the fixed point PA crosses the light guide plate 70. The edge 303 of the deflector 30d is where the extension of a line connecting the point 501 and the fixed point PD crosses the light guide plate 70. The edge 301 of the deflector 30d is where the extension of a line connecting the point 502 and the fixed point PD crosses the light guide plate 70.Therefore, a viewer can see both the set point PA and the set point PD when the viewer's eyes are on the line segment between point 501 and point 502. In contrast, a viewer cannot see either the fixed point PA or the fixed point PD when the viewer's eyes are on an extension of the line segment between point 501 and point 502.The other deflectors 30 in the light guide plate 70 are similar to the deflector 30 aand the deflector 30 dsuch that one end of a deflector 30 is along an extension line passing through the point 501 and the other end of the deflector 30 is along an extension line passing through the point 502. Thus, a viewer can see the entire image 6 without a portion of the image 6 appearing missing when the viewer's eye is on a line segment between point 501 and point 502. In contrast, a viewer can see absolutely nothing from the image 6 when the viewer's eyes are on an extension of the line segment between point 501 and point 502. That is, the display device 10 in FIG. 5 allows a viewer to see the image 6 only when the viewer's eyes are on a line segment connecting the point 501 and the point 502. The viewer cannot see any of the points in the image 6 when the viewer's eyes are outside the line segment. Thus, the position and range of deflectors 30 may be defined to prevent a viewer from viewing only a portion of image 6 when the viewer's eyes can be predicted to be at a certain distance 71 from the emission surface.FIG. 6 is an exploded view of a portion of FIG. 3 ; here, the deflector 30 dincludes a first segment 610 and a second segment 620 delimited by an intersection c between the line 312 and the rear surface 72. The first segment 610 is closer to the edge 301 from the intersection c; the second segment 620 is closer to the edge 303 from the intersection c; and the line 312 coincides with the optical axis of the light converging on the point PD.The deflector 30 includes a first segment 610 near one edge and a second segment 620 near the other edge in the xz plane around a position corresponding to the line 312. Light emitted by the first segment 610 and light emitted by the second segment 620 are asymmetric about the line 312. In addition, the length w 1 of the first segment 610 in the direction of the x-axis and the length w 2 of the second segment 620 in the direction of the x-axis in the xz plane are different. The first segment 610 and the second segment 620 may be considered to have asymmetric lengths.Thus, at least one of the deflectors 30 of the plurality of deflectors 30 includes a first segment proximate one edge and the second segment proximate the other edge thereof. The first segment and the second segment are located around a position corresponding to the optical axis of light converging to or radiating from a converging point or line in a plane orthogonal to the direction along which light is guided from the light guide plate. Light emitted by the first segment 610 and light emitted by the second segment 620 are asymmetric about the optical axis. For example, the lengths of the first segment 610 and the second segment 620 in a direction parallel to the emission surface 71 differ in a plane orthogonal to the direction along which light is guided from the light guide plate.The deflectors 30 may be constructed with an observation position defined therefor; it should be noted that, in this case, typically a deflector 30 near at least one edge of the light guide plate 70 in the direction of the x-axis has a greater degree of asymmetry than a deflector 30 near the center of the light guide plate 70.FIG. 7 shows a display device 700 as a comparative example of the display device 10; FIG. 7 shows a section corresponding to FIG. 6. the deflectors 730 in the display device 700 correspond to the deflectors 30 d. A deflector 730 is configured such that the divergence angle of light radiated from the fixed point PD is an angle θ about the optical axis. The optical axis of the light emitted from a deflector 730 is orthogonal to the emission surface when projected on this xz plane. Similarly, the optical axis of the light emitted from each of the other deflectors is orthogonal to the emission surface when projected on this xz plane. The light emitted from the deflectors 730 is symmetrical about the optical axis. Thereby, the light emitted from the deflectors 30 illustrated in FIG. 6 and the light emitted from the deflectors 730 in FIG. 7 illustrating a comparative example have different symmetry about the optical axis.The light emitted from a segment 710 of the deflector 730 toward the negative x direction from the crossover point c is symmetrical to the light emitted from a segment 720 of the deflector 730 toward the positive x direction from the crossover point c. The lengths w of segment 710 and segment 720 are also equal. Thus, the deflectors 30 described with reference to FIG. 6 and the deflectors illustrating the comparative example in FIG. 7 are optically different structures.Note that light from the deflectors 730 does not pass through the observation position 380. Therefore, a viewer at the observation position 380 does not recognize the set point PD. Here, disposing the deflectors without considering the observation position may result in an image in which a portion thereof cannot be seen from the observation position. In order to ensure that a viewer at the observation position 380 can see the entire image 6, the divergence angle of light emitted from the fixed point PD around the optical axis in the display device 700 needs to be expanded to θ', as illustrated by the broken lines in FIG. 7. This increases the surface area forming the deflector. As the surface area of the deflector increases, the machining cost for manufacturing the deflector also increases. In addition, the light guide plate is less transmissive overall.In contrast, the display device 10 described with reference to FIGS. 1 to 6 is capable of reducing the processing cost for manufacturing the deflectors 30 as described above. In addition, the light guide plate 70 is more transmissive as a whole.FIG. 8 illustrates a cross section of a display device 10A as a comparative example of the display device 10; FIG. 8 illustrates the set point PD and light beams projected on the xy plane. The deflectors 30A correspond to the deflectors 30 din the display device 10. the first segment 610A corresponds to the first segment 610 in the display device 10. the second segment 620A corresponds to the second segment 620 in the display device 10. the deflector 13A includes a plurality of reflecting surfaces 31A corresponding to the reflecting surfaces 31 in the display device 10.The plurality of reflection surfaces 831 are shown by lines in FIG. 8. The line representing a reflection surface 831 crosses a plane parallel to the xy plane. It is assumed that the light entering the light guide plate 70 in the display device 10A is substantially parallel light in the xy plane. That is, the light guide plate 70 substantially guides light parallel to the emission surface 71 in the xy plane.The plurality of reflection surfaces 31A are asymmetrically aligned about the center of the deflectors 30 in the display device 10A. The plurality of reflection surfaces 31A are also aligned asymmetrically relative to the intersection c between the optical axis of the light radiating from the fixed point PD and the light guide plate 70. Thus, the plurality of reflection surfaces in the first segment 610A and the plurality of reflection surfaces in the second segment 620A are asymmetrically aligned around a position corresponding to a line connecting a convergence point or a convergence line and an observation position even when the light guided by the light guide plate 70 is substantially parallel light.FIG. 9 shows a display device 900 as a comparative example of the display device 10A; FIG. 9 shows a section corresponding to FIG. 8, and deflectors 930 in the display device 900 correspond to the deflectors 30 d. The deflectors 930 correspond to the deflectors 730 in FIG. 7, and it is assumed that the light emitted from the deflectors 930 has optical characteristics identical to those emitted from the deflectors 730 in FIG. 7.A deflector 930 includes a plurality of reflective surfaces 931. The plurality of reflection surfaces 931 are represented by lines in FIG. 9. The line representing a reflection surface 931 crosses a plane parallel to the xy plane. The reflection surfaces 931 are symmetrically aligned relative to the intersection c and the optical axis L of the light emitted from the fixed point PD.Thereby, the reflection surfaces 931 may be symmetrically oriented relative to the intersection c when the deflectors 930 are constructed without a defined observation position for substantially parallel light guided by the light guide plate 70 through the xy plane. In contrast, as described with reference to FIG. 8, the reflecting surfaces are asymmetrically oriented relative to the intersection c when the deflectors 30 are constructed with a defined observation position.In this way, the structure of the reflection surfaces on the deflectors 30A in FIG. 8 has different symmetry than the structure of the reflection surfaces on the deflectors 930 in FIG. 9.FIG. 10 illustrates a cross section of a display device 10B as a comparative example of the display device 10. FIG. 10 illustrates deflectors 1030 acorresponding to the deflectors 30 aand the deflectors 1030 dcorresponding to the deflectors 30 d.A deflector 1030A is configured such that the light radiating from the fixed point PA creates an angle θ about the optical axis La. The light emitted from the deflectors 1030 apass through a predetermined region including the observation position 380. Therefore, the deflectors 1030 amay be employed in the display unit 10B as deflectors that supply light from the specified point PA to the observation position 380.Deflectors 1030d include a segment 1001 configured such that light emitted therefrom converges at the fixed point PD and creates an angle about the optical axis Ld. It is noted that light from the segment 1001 does not pass through the observation position 380.In addition to segment 1001, deflectors 1030D also include segment 1002 toward the negative x-axis. The segment 1002 is positioned such that light from the segment 1002 passes through a predetermined area including the observation position 380. Deflectors 1030 dinclude no additional segments in the direction of the positive x-axis relative to segment 1001. The establishment of an observation position therefore makes it possible to provide deflectors only on the segments required for emitting light passing through the observation position; therefore, it is possible to control significant magnifications of the surface area on the light guide plate 70 on which the deflectors are formed.FIGS. 11A and 11B are schematic views of a deflector 130 and a deflector 132 as comparative examples of the deflector 30, and FIG. 11A outlines a single deflector 130 formed of a part of a Fresnel lens. The plurality of refraction surfaces (prism surfaces) in the deflector 130 may have gaps therebetween, the plurality of refraction surfaces and the gaps acting as a Fresnel lens.The deflectors 132 illustrated in FIG. 11B correspond to a deflector 130 divided into a plurality of segments along the x-axis direction, i.e., a segment 140 a, a segment 140 b, a segment 140 c, a segment 140 d, a segment 140 e, a segment 140 f, a segment 140 g, and a segment 140 h. Light from each of the segments in the deflector 132 converges at the same fixed point or radiates therefrom. Thus, dividing the deflector into multiple segments may increase the contrast of the image. Note that, in addition to a reflection surface or a Fresnel lens, a diffraction grating may also be used as a deflector 30.FIG. 12 is a schematic view of a display device 210 according to a second non-claimed embodiment together with an image projected into a space. The components in the display device 210 having reference numerals identical to the components in the display device 10 have an identical configuration. In the description of the second embodiment, descriptions of the configurations identical to those in the display device 10 are omitted, and differences will be mainly described.In the embodiment, the image 6 is an image of the character "A" in a plane 9 located on the positive side of the z-axis from the emission surface 71. The plane 9 is parallel to the xy plane. The display device 210 is provided with a light guide plate 70, a light source 220, and a light incidence tuning section 50.The light source 220 may include a light emitting diode (LED). Light from the light source 220 is adjusted by the light incidence adjusting section 50 and enters the light guide plate 70 as incident light via the first edge 73.A plurality of deflectors 230 are provided on the rear surface 72 of the light guide plate 70; the plurality of deflectors 230 include a deflector 230 a, a deflector 230 b, and a deflector 230 c. The deflectors 230 may be provided two-dimensionally in the xy plane. The deflectors 230 may be provided in a matrix in the xy plane. Light guided by the light guide plate 70 enters the deflectors 230.The deflector 230 a, the deflector 230 b, and the deflector 230 ceach deflect light propagating through the light guide plate 70 and each cause the light to exit from the emission surface 71 to draw the image 6. More specifically, deflector 230a causes emission surface 71 to emit bonded light for various locations in image 6. The deflector 230 a deflectors the light guided thereto from the light guide plate 70 such that the light propagates in the xy plane and the yz plane and travels to various locations in the image 6. FIG. 12 illustrates a state in which light from the deflector 230 apropagates toward a number of locations in the image 6. The deflector 230 band the deflector 230 cbehaving identically together with the other deflectors 230, respectively. Deflectors 230 fill a microscopic area on back surface 72. Each of the deflectors 230 fills a smaller surface area than when projected on the image 6 in the xy plane. The image 6 is generated from light propagating from each deflector 230 of the plurality of deflectors 230 towards different locations in the image 6. That is, the light from a plurality of deflectors 230 produces the light emitted from the direction of the image 6. The light that generates the image 6 may be provided by at least three deflectors 230 that are not along the same straight line. That is, each of the deflectors 230 converts light entering therein into light having an intensity distribution according to the image 6 that propagates two-dimensionally and exits from the emission surface. Thus, the light from the three or more deflectors 230 that do not lie on the same straight line forms the image 6. The display device 210 may thereby project a three-dimensional image into a space. The display device 210 groups the light beams from the plurality of deflectors 230 that are not on the same straight line to provide a viewer with light beams radiating from the image 6. Therefore, a viewer can perceive the image 6 regardless of whether the image is viewed from the x-axis direction or the y-axis direction.FIG. 13 schematically illustrates a cross section of the display device 210 in the yz plane; and FIG. 14 is a schematic view illustrating an example of an optical element 231 including a deflector 230.The light source 220 may include an LED 21. A plurality of LEDs 21 are arranged along the direction of the x-axis. The optical axis of the light emitted from the LEDs 21 forms an angle η with the emission surface 71. The narrow angle η between the optical axis of the light emitted from the LEDs 21 and the emission surface 71 is less than 20°. The light emitted from the LEDs 21 enters the light incidence tuning section 50.The light incidence adjusting section 50 includes lenses 51. the lenses 51 arranged along the x-axis direction are each paired with one LED 21 of the plurality of LEDs 21. Each of the lenses 51 reduces the spread of light traveling along the optical axis for the light emitted from the LED 21 corresponding thereto. The lenses 51 make light emitted from the LEDs 21 nearly parallel light. For example, the lenses 51 can reduce the angle of propagation of the light emitted from the LEDs 21 in the xy plane. The lenses 51 can also reduce the spread angle of the light emitted from the LEDs 21 in the yz plane. Here, light may enter the light guide plate 70 as nearly parallel light.Here, the light beams in the xy plane guided by the light guide plate 70 and passing through locations in the light guide plate 70 propagate at an angle of a predetermined value and advance from the locations in the light guide plate 70 around a direction connecting the locations in the light guide plate 70 and the light source 220. In this specification, it is assumed that the light propagating from a certain point when light beams pass through and advance through the certain point in or outside the light guide plate has been outputted from this point and is simply referred to as "propagation of light" or the like. The angle of this propagation of light is simply referred to as the "propagation angle.". In a light intensity distribution along an angular direction, the spread angle may be the position at which the light intensity is half maximum (full width at half maximum). The propagation angle of the light guided by the light guide plate 70 may be less than or equal to 5°. The angle of propagation of the light can ideally be less than 1°. When projected onto the xy plane, the angle of propagation of the light may be less than or equal to 5°, and ideally less than 1°. When projected onto the yz plane, the angle of propagation of the light may be less than or equal to 5° and may ideally be less than 1°.As illustrated in FIGS. 13 and 14, the deflector 230 aincludes a reflection surface 40 a. The deflector 230 aincludes also a reflection surface 40 b, a reflection surface 40 c, a reflection surface 40 d, and a reflection surface 40 e. The reflection surface 40 is an example of an optical surface that functions as a deflection surface that deflects light. The reflection surface 40 a, the reflection surface 40 b, the reflection surface 40 c, the reflection surface 40 d, and the reflection surface 40 eare curved surfaces oriented in different directions. As described above, the optical axes of the LEDs 21 are inclined in the yz plane relative to the emission surface 71 by an angle η. Therefore, even when the light entering the light guide plate 70 approaches parallel light, a larger amount of light is repeatedly reflected by and diffused between the emission surface 71 and the back surface 72 of the light guide plate 70 compared to a case where the optical axis of incident light is parallel to the y-axis. As a result, a larger amount of light is incident on the reflection surface 40 as compared with when the optical axis of the incident light is parallel to the y-axis.The reflection surface 40 acauses light incident thereon to be emitted from the emission surface 71 at a different emission angle depending on where the light is incident on the reflection surface 40 a. The reflection surface 40a causes light incident thereon to propagate within a region 61 in the image 6. In this embodiment, the region 61 is a region parallel to the y-axis. The light reflected by the reflection surface 40a is directed from the reflection surface 40a to where the region 61 exists, and substantially no light reflected by the reflection surface 40a passes to where the region 61 does not exist. Accordingly, the light reflected from the reflection surface 40 ais substantially only distributed at angles within the yz plane from the reflection surface 40 ato the region 61. Thus, the reflection surface 40 amodulates the intensity of incident light in the yz plane in an angular direction and outputs the light. The reflection surface 40 ais a curved surface; therefore, the reflection surface 40 ais still capable of making light forming lines that form the image even when the light incident thereon is parallel light.The reflecting surface 40b reflects the light incident thereon, the light being propagated within a region 62 in the image 6. Region 62 forms a portion of character 'A' between an intersection with region 61 on the negative y-axis and the furthest endpoint along the positive x-axis. The reflecting surface 40c reflects the light incident thereon, the light being diffused within a region 63 in the image 6. Region 63 forms a portion of character 'A' between an intersection with region 61 on the positive y-axis and the furthest endpoint along the positive x-axis. The reflecting surface 40d reflects the light incident thereon, the light being propagated within a region 64 in the image 6. Region 64 forms a portion of character 'A' between an intersection with region 61 on the negative y-axis and the furthest endpoint along the negative x-axis. The reflecting surface 40e reflects the light incident thereon, the light being propagated within a region 65 in the image 6. Region 65 forms a portion of character 'A' between an intersection with region 61 on the positive y-axis and the furthest endpoint along the negative x-axis. Since the reflection surface 40 b, the reflection surface 40 c, the reflection surface 40 d, and the reflection surface 40 eare all curved, each of the reflection surfaces 40 can produce light forming lines that form the image even when the light incident thereon is parallel light.Thus, the reflection surface 40 apropagates light incident thereon with an intensity distribution according to at least the image of the region 61 along the z-axis, and causes emission of the light. The reflection surface 40 bpropagates light incident thereon with an intensity distribution according to at least the image of the region 62 along the x-axis, and causes emission of the light. The reflection surface 40c propagates light incident thereon with an intensity distribution according to at least the image of the region 63 along the x-axis, and causes emission of the light. The reflection surface 40 dpropagates light incident thereon with an intensity distribution according to at least the image of the region 64 along the x-axis, and causes emission of the light. The reflection surface 40 epropagates light incident thereon with an intensity distribution according to at least the image of the region 64 along the x-axis, and causes emission of the light. Thus, the deflector 230a has a plurality of reflecting surfaces which reflect light toward lines in the image 6, the deflector 230a modulating the intensity of the incident light two-dimensionally or in two directions according to the image 6, and causing emission of the light from the emitting surface 71. Here, a single deflector 230a provides light beams which pass substantially all of the image 6.The deflector 230 bincludes a reflection surface 41 b. Similarly to the reflection surface 40 a, the reflection surface 41 bcauses light incident thereon to be emitted from the emission surface 71 at a different emission angle depending on where the light is incident on the reflection surface 41 b. Specifically, the light reflected from the reflection surface 41 bpropagates within a region 61 in the image 6. FIG. 14 illustrates only the reflection surface 40 aand the reflection surface 41 b; however, each of the deflectors 230 includes a reflection surface that propagates the incident light within the region 61. Each of the deflectors 230 includes a plurality of reflective surfaces that reflect light toward lines within the image 6, similar to the deflector 230 a. Each of the deflectors 230 modulates the intensity of light incident thereon two-dimensionally or in two directions according to the image 6 and causes emission of the light from the emission surface 71 Thus, each of the deflectors 230 provides light beams that pass substantially all of the image 6.The light emitted from the emission surface 71 is actually refracted inside the emission surface 71. Thus, deflectors 230 are designed to account for refraction within emission surface 71. However, for convenience, this embodiment will be described as if there is no refraction in the emission surface 71.FIG. 15 schematically illustrates a deflector 230 providing light moving to a particular observation position. For example, the light making the region 62 is provided from a particular reflection surface in the deflector 230 eand a particular reflection surface in the deflector 230 f, while no light is provided from the deflector 230 dand the deflector 230 g. Thus, a certain part of the image 6 is generated by certain parts of a certain deflector 230 among the plurality of deflectors 230 when the image is viewed from a certain observation position.The display device 210 is configured such that each of the plurality of deflectors 230 provided two-dimensionally in the xy plane provides light passing through all locations in the image 6. Therefore, the three-dimensional image can be viewed over a wide range. Since the display device is also capable of displaying light from a specific location in the xy plane passing through locations in the entire image 6, the three-dimensional image is formed as a plane rather than a point.FIG. 16 illustrates the relationship among a reflection surface 40 a, a reflection surface 41 b, and an observation position 380. The reflection surface 40 ais configured such that one of the light beams in the light emitted from the emission surface 71 via the reflection surfaces 40 passes through the observation position 380. The reflection surface 41 bis configured such that one of the light beams in the light emitted from the emission surface 71 via the reflection surfaces 40 passes through the observation position 380. In contrast, at the location where the light would not pass through the observation position 380, no reflection surfaces are provided in the display device 200. Thus, each of the reflection surfaces 40, 41 of the plurality of reflection surfaces 40, 41 is configured such that one of the light beams in the light emitted from the emission surface 71 via the reflection surfaces 40, 41 passes through a specific observation position 380 in a space. Consequently, it is possible to reduce the surface area of the region in the light guide plate 70 where the reflection surfaces 40 need to be formed, similarly to the display device 10 in the first embodiment and the modifications thereto.FIG. 17 is a schematic view of a deflector 330 as a comparative example of the deflector 230. The deflector 330 includes a plurality of optical elements 331 provided at separate locations. The optical elements 331 each have a single flat reflection surface. The reflection surfaces of the optical elements 331 respectively reflect light incident thereon to different points from each other in the image 6.The optical elements 331 may all be separately provided or may be provided such that a part thereof is connected. The distribution pattern for the optical elements 331 may differ depending on the location where the deflectors 330 are provided.FIG. 18 is a schematic perspective view of a deflector 230A as a comparative example of the deflector 230; the deflector 230A has a completely convex reflection surface. The deflector 230A is provided on the rear surface 72 of the light guide plate 70. The convex reflecting surface of the deflector 230A deflects the light guided by the light guide plate 70 such that the light beams passing through the plane 9 including the image 6 exit from the emitting surface 71.The portions of the deflector 230A that do not correspond to the generation of the character 'A' are provided with an anti-reflective film 110. The light entering at parts where the antireflection film 110 is formed on the deflector 230A is not substantially reflected therefrom. Only the light entering the deflector 230A at portions without the antireflection film 110 is reflected therefrom. Thus, the deflector 230A deflects the light entering therein such that the light rays passing through the character 'A' of the image 6 exit the emission surface 71. The antireflection film 110 can be manufactured by, for example, coating black coloring material on portions of the back surface 72 other than the portion forming the mark 'A'. The antireflection film 110 can be produced by printing black coloring material on areas other than the area forming the mark 'A'. Since the deflectors 230A can be formed by printing the black color material after forming the convex portion on the light guide plate 70, this simplifies the manufacturing process of the deflectors.FIGS. 19, 20A and 20B serve to describe how a deflector 230G is formed as a comparison with the deflector 230A. The deflector 230G may be provided as a part of a Fresnel lens.The optical surfaces forming the Fresnel lens are provided on the back surface 72 of the light guide plate 70 for each deflector 230. FIGS. 20A and 20B illustrate when a Fresnel lens is generated for a single deflector 230G. The Fresnel lens portion in each of the deflectors 230 deflects light guided by the light guide plate 70 so that the light beams passing through the plane 9 including the image 6 exit the emission surface 71.FIGS. 21A, 21B, and 21C schematically illustrate additional examples of the shape of an optical element 231; FIG. 21A is a perspective view of an optical element 231; and FIG. 21B illustrates when the reflection surface 40 is projected on the xy plane. When the reflection surface 40 is projected on the xy plane, the outer shape in the positive y-axis direction and the outer shape in the negative y-axis direction, which outline the reflection surface 40, are concentric arcs. The outer shape in the negative y-axis direction of the reflection surface 40 projected on the xy-plane may be referred to as the front outline, while the outer shape in the positive y-axis direction is referred to as the rear outline. The front contour and the rear contour of the reflecting surface 40 form concentric arcs.When cut along a plane parallel to the zyg level, the intersection line between the optical element 231 illustrated in FIGS. 21A and 21B and the reflection surface 40 is a straight line. However, since the front contour and the rear contour are curved, the reflection surface 40 in FIG. 21 is a curved surface. Thus, a single reflective surface 40 may represent the light needed to generate a line or plane that forms at least a portion of the image.FIG. 21C schematically illustrates additional examples of the shape of the reflection surface of an optical element 231. FIG. 21C illustrates the shape of a reflection surface 40 projected on the xy plane. As can be seen in FIG. 21C, the front outline and a rear outline forming the concentric arcs that outline the reflection surface 40 are divided to provide a reflection surface 40 divided into a plurality of parts.FIGS. 22A, 22B, and 22C schematically illustrate examples of distributing the optical elements 231 in the xy plane. FIG. 22A illustrates an example in which a plurality of optical elements 231 form a line along the y-axis direction. FIG. 22B is a modified version of the example in FIG. 22A, and illustrates an example in which optical elements 231 are distributed such that when the optical elements 231 aligned along the y-axis direction are viewed in the row, they are shifted along the x-axis direction by a fixed offset. FIG. 22C illustrates an example in which the optical elements 231 are continuously distributed as a single element along the direction of the x-axis. In FIG. 22C, the end portions of optical elements adjacent in the x-axis direction are connected to provide a single optical element. The lines in FIG. 22C correspond to the end portions of adjacent optical elements in the direction of the x-axis.FIGS. 23A and 23B schematically illustrate additional examples of the shape of the reflection surface of an optical element 231. FIG. 23A is a perspective view of an optical element 231; and FIG. 23B illustrates when the reflection surface 40 of the optical element 231 is projected on the xy plane. The optical element 231 is formed of three planes having mutually different line directions of the normal. When the reflection surface 40 is projected on the xy plane, each of the front outlines and the rear outlines form three polygonal lines extending in different directions. Since the reflection surface 40 illustrated in FIG. 23 is flat, the light entering each of the reflection surfaces 40 is directed in three different directions from each other. Therefore, the optical element 231 illustrated in FIGS. 23A, 23B can represent light that generates three points that are part of the image.FIGS. 24A and 24B schematically illustrate additional examples of the shape of the reflection surface of an optical element 231. The reflection surfaces 40 in the optical element 231 illustrated in FIG. 24A and FIG. 24B are different from the optical element 231 illustrated in FIG. 21A ; that is, the grooves of the reflection surface 40 in the z-axis positive direction have different heights in the z-axis direction. When projected on the xz plane, the groove of the reflecting surface 40 changes in the positive z-axis direction continuously along the x-axis direction; when cut along a plane parallel to the yz plane, the linear length of the reflecting surface 40 changes along the x-axis direction. The intensity of the light reflected by the reflection surface 40 therefore changes along the direction of the x-axis. Thus, the optical element 231 illustrated in FIGS. 24A and 24B may represent light for generating an image of lines with its luminance changing along the x direction.The display device 210 and the modifications thereof described with reference to FIGS. 12 to 24B are configured such that each of the optical deflectors two-dimensionally provided in a plane parallel to the emission surface of the light guide plate 70 supplies light that generates images at multiple locations in the three-dimensional image. Therefore, the three-dimensional image can be viewed over a wide range. At least a part of the three-dimensional image may also be formed as a plane and not necessarily as a point. In addition, as described with reference to FIG. 16, the deflectors 230 are configured such that one of the light beams in the light exiting from each of the deflectors 230 passes through the observation position 380. This therefore reduces the surface area of the area on the light guide plate 70 on which the reflection surfaces 40 are formed.Thus, each of the reflection surfaces 40, 41 of the plurality of reflection surfaces 40, 41 is configured such that one of the light beams in the light emitted from the emission surface 71 via the reflection surfaces 40, 41 passes through a specific observation position 380 in a space. Consequently, it is possible to reduce the surface area of the region in the light guide plate 70 where the reflection surfaces 40 need to be formed, similarly to the display device 10 in the first embodiment and the modifications thereto.FIG. 25 is a schematic view of an image 16 formed by a display device 2010 as a comparative example of the display device 10. The image 16 represents a key; the image 16 includes a segment image 17 representing an input surface that can be perceived in a space. A sensor for detecting the proximity of an object to the segment image 17 may be used with the display device 2010 to provide an operation input device serving as a virtual switch. This operation input device can be used as the input device for an ATM or an automobile instrument panel or the like. The location of the eyes of a user of an ATM or an automobile device is substantially fixed. Therefore, the deflectors in the display device 2010 may be configured according to an observation position as described above. Thus, the surface area of the region where the deflectors 30 are to be formed is reduced.Note that a display device configured identically to the display device 10 and the modification examples thereof, the display device 210, and the modification examples thereof is not limited to a game machine, an ATM, or an instrument panel. The display device may be used as a dashboard display device or in place of the door mirror for automotive applications.

Claims

An optical device (10) comprising: a light guide plate (70) configured to guide light in a plane parallel to an emission surface (71); and a plurality of deflectors (30) configured to deflect light guided thereto from the light guide plate (70), thereby causing light forming an image in a space outside the light guide plate (70) to exit from the emission surface (71); wherein: each deflector (30) of the plurality of deflectors (30) causes the light to exit from the emission surface (71) in a direction converging on a single convergence point or a convergence line in the space or to radiate from a single convergence point or a convergence line in the space; and the convergence point or the convergence line are different from each other among the plurality of deflectors (30) having a grouping of a plurality of the convergence points or the convergence lines forming the image in the space; each deflector (30) of the plurality of deflectors (30) is configured such that one of the light beams in the light emitted from the emission surface (71) passes through a specific observation position (380) in the space via the deflector (30); at least one of the deflectors (30) among the plurality of deflectors (30) is configured such that, when a first line connects an edge of the deflector (30) and the convergence point or the convergence line and a second line connects the convergence point or the convergence line to the observation position (30), the first line is disposed between the location where the second line or an extension thereof crosses the light guide plate (70) and the one edge (301) of the deflector such that the first line and the second line do not form greater than a predetermined angle in a plane orthogonal to the direction along which light is guided by the light guide plate (70); at least one of the deflectors (30) of the plurality of deflectors (30) includes a first segment (610) near one edge and a second segment (620) near another edge, the first segment (610) and the second segment (620) being located around a position corresponding to the optical axis of light converging to or radiating from the converging point or the converging line in a plane orthogonal to the direction along which light is guided by the light guide plate (70); and the light emitted from the first segment (610) and the light emitted from the second segment (620) are asymmetric around the optical axis.The optical device (10) according to claim 1, wherein: each deflector (30) of the plurality of deflectors (30) is configured such that, when a third line connects another edge of the at least one deflector (30) and the convergence point or the convergence line, the third line is disposed between the location where the second line or an extension thereof crosses the light guide plate (70) and the other edge of the deflector (30) such that the third line and the second line do not form greater than a predetermined angle in a plane orthogonal to the direction along which light is guided by the light guide plate (70).The optical device (10) according to claim 1 or 2, wherein: the plurality of deflectors (30) are formed along a predetermined line in a plane parallel to the emission surface (71).The optical device (10) according to any one of claims 1 to 3, wherein: at least one of the deflectors (30) of the plurality of deflectors (30) includes a first segment (610) near one edge and a second segment (620) near another edge, the first segment (610) and the second segment (620) being located around a position corresponding to the optical axis of light converging to or radiating from the converging point or the converging line in a plane orthogonal to the direction along which light is guided by the light guide plate; and the length of the first segment (610) in a direction parallel to the emission surface (71) and the length of the second segment (620) in a direction parallel to the emission surface (71) are asymmetric in a plane orthogonal to the direction along which light is guided by the light guide plate (70).The optical device (10) according to claim 4, wherein: the light guided by the light guide plate (71) is parallel in a plane parallel to the emission surface (71); the first segment (610) and the second segment (620) each include a plurality of deflection surfaces configured to deflect light incident thereon; and the plurality of deflection surfaces in the first segment (610) and the plurality of deflection surfaces in the second segment (620) are asymmetrically aligned about a position corresponding to a line connecting the convergence point or a convergence line and the observation position (380).The optical device (10) according to claim 4 or 5, wherein: the degree of asymmetry for a deflector (30) disposed near an edge of the light guide plate (70) is greater than the degree of asymmetry for a deflector (30) disposed near the center of the light guide plate (70).An optical device (10) comprising: a light guide plate (70) configured to guide light in a plane parallel to an emission surface (71); and a plurality of deflectors (30) arranged two-dimensionally in a plane parallel to the emission surface (71), and each deflector (30) is configured to deflect light guided thereto by the light guide plate (70), thereby causing the light forming an image in a space to exit from the emission surface (71); wherein: each deflector (30) of the plurality of deflectors (30) is configured to spread the light incident thereon into light having an intensity distribution corresponding to the image in a direction orthogonal to the light guiding direction of the light guide plate (70) in a plane parallel to the emission surface (71) and cause the emission surface (71) to output the light such that grouping of the light from a plurality of deflectors (30) arranged along a direction orthogonal to the light guiding direction thereby forms the light emitting from the image; and each deflector (30) of the plurality of deflectors (30) is configured such that one of the light beams in the light emitted from the emission surface (71) passes through a certain observation position (380) in the space via the deflector (30); at least one of the deflectors (30) of the plurality of deflectors (30) includes a first segment (610) near one edge and a second segment (620) near another edge, the first segment (610) and the second segment (620) being located around a position corresponding to the optical axis of light converging to or radiating from the converging point or the converging line in a plane orthogonal to the direction along which light is guided by the light guide plate (70); and the light emitted from the first segment (610) and the light emitted from the second segment (620) are asymmetric around the optical axis.The optical device (10) according to any one of claims 1 to 7, further comprising: a light source (20) configured to emit light guided by the light guide plate (70).

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