Optical device

An optical device has a light guide plate configured to guide light within a plane parallel to an emission surface thereof, and a plurality of optical deflectors arranged two-dimensionally within a plane parallel to the emission surface. Each of the optical deflectors deflects light propagating through the light guide plate, and causes the emission surface to output light forming an image in a space. Each of the optical deflectors is configured to spread the light incident thereon that has an intensity distribution corresponding to an image in a direction orthogonal to the light guide direction of the light guide plate in a plane parallel to the emission surface, and cause the emission surface to output the light which groups the light from the plurality of optical deflectors arranged along a direction orthogonal to the light guide direction, such that light radiating from the image is formed.

BACKGROUND

Field

The present invention relates to an optical device.

Related Art

Stereoscopic displays are known. A stereoscopic display is equipped with a light guide plate and a light source placed at an edge of the light guide plate, and depending on whether the display uses a parallax barrier or a lens array, a mask or a lens array provided at the front surface of the light guide plate (e.g., Japanese Patent Publication No. 2012-008464). A display device that presents a two dimensional image stereoscopically is also known. More specifically, the display device is made up of a display unit provided with an image display surface that shows a two dimensional image, and a microlens array separated from the image display surface. The light emitted from the image display surface creates an image in an image forming plane located on the side of the display unit opposite the microlens array, and thus presents the two dimensional image stereoscopically (e.g., Japanese Patent Publication No. 2001-255493).

SUMMARY

Existing devices require some kind of optical component, e.g., a mask or a lens array to show a three-dimensional image. The optical components such as the mask or lens array must be closely aligned with other optical components such as the light guide plate, or the color liquid crystal display device, or the like in order to clearly show a three-dimensional image. Furthermore, it tends to be difficult to provide more situations where the light guide plate may be used to present a three-dimensional image.

In a first embodiment, an optical device includes a light guide plate configured to guide light within a plane parallel to an emission surface; and a plurality of optical deflectors arranged two-dimensionally within a plane parallel to the emission surface, the optical deflectors each deflecting light propagating through the light guide plate and causing the emission surface to output light forming an image in a space; wherein each optical deflector in the plurality of optical deflectors is configured to spread the light incident thereon that has an intensity distribution corresponding to an image in a direction orthogonal to the light guide direction of the light guide plate in a plane parallel to the emission surface and cause the emission surface to output said light which groups the light from the plurality of optical deflectors arranged along a direction orthogonal to the light guide direction and thereby produces light radiating from the image.

In a second embodiment, an optical device includes a light guide plate configured to guide light within a plane parallel to an emission surface; and a plurality of optical deflectors arranged two-dimensionally within a plane parallel to the emission surface, the optical deflectors each deflecting light propagating through the light guide plate and causing the emission surface to output light forming an image in a space; wherein each optical deflector in the plurality of optical deflectors configured to spread the light incident thereon that has an intensity distribution corresponding to the image two-dimensionally and cause the emission surface to output said light which groups the light from three or more optical deflectors on different straight lines and thereby produces light radiating from the image.

The optical device may be configured so that each optical deflector in the plurality of optical deflectors is provided with a single group or a plurality of groups of reflective, refractive, or diffractive deflection surface on the surface or inside the light guide plate and inclined relative to the emission surface.

At least one of the deflection surfaces may be configured to include a plurality of planar or curved surfaces oriented in different directions.

At least one of said deflection surfaces may be configured to extend in a direction orthogonal to the light guide direction of the light guide plate and have polygonal lines or curved lines when projected onto a plane parallel to the emission surface.

At least a portion of the plurality of optical deflectors may be configured to include a plurality of deflection surfaces extending linearly when the optical deflector is projected onto a plane parallel to the emission surface.

At least a portion of the plurality of optical deflectors may be configured to include a plurality of deflection surfaces extending along a curve and one or more linear deflection surfaces when the optical deflector is projected onto a plane parallel to the emission surface.

At least a portion of the plurality of optical deflectors may be configured to include a deflection surface forming a part of a Fresnel lens arranged at a location corresponding to the image.

At least a portion of the plurality of optical deflectors may be configured to include one or more deflection surfaces having a shape following an arc when the optical deflector is projected onto a plane parallel to the emission surface.

The plurality of deflection surfaces may be formed uniformly for the most part on the emission surface or a surface opposite the emission surface of the light guide plate, the deflection surfaces configured to spread light incident thereon in a range containing the image and cause the emission surface to output said light; and the optical device further including: a photo-reflective material provided on a portion of the plurality of deflection surfaces uniformly provided; and the plurality of uniformly formed deflection surfaces which are provided with the reflective material form the at least one portion of the plurality of optical deflectors.

The optical device may further include an optical component configured to include at least a portion of the plurality of optical deflectors, and arranged on the emission surface or a surface opposite the emission surface.

The plurality of deflection surfaces may be formed uniformly for the most part on the emission surface or a surface opposite the emission surface of the light guide plate, the deflection surfaces configured to spread light incident thereon in a range containing the image and cause the emission surface to output said light; and the optical device further including: an optical component having a refractive index substantially identical to the refractive index of the light guide plate, and configured with a surface in contact with a portion of the plurality of uniformly formed deflection surfaces; and the plurality of uniformly provided deflection surfaces not in contact with the surface of the optical component form the at least one portion of the plurality of optical deflectors.

At least a portion of the plurality of optical deflectors may be configured to include a deflection surface having a shape following an arc with a center of curvature toward the light source when the optical deflector is projected onto a plane parallel to the emission surface.

A light source may also be provided.

Note that the above summary does not list all the features of the present invention. Sub combinations of these sets of features are also within the scope of the invention.

DETAILED DESCRIPTION

Embodiments of the present invention are described below with reference to the drawings. However, the below embodiments are not limiting on the present invention. Not all combinations of the features described in the below embodiments are required. In embodiments of the invention, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid obscuring the invention.

FIG. 1schematically illustrates an optical device (display device10) according to one or more embodiments of the present invention, and an image formed in a space. The drawings used for describing one or more embodiments of the present invention may be general and schematic in nature in order to provide a clear explanation. In some cases, the drawings are not to scale. The drawings that include a three-dimensional image are not necessarily drawn from the point of view of an observer and may be drawn from a different perspective to ensure the location the image in a space is easy to understand.

The display device10includes an emission surface71that emits light. The display device10uses light emitted from the emission surface71to produce a three-dimensional image6in a space. A user can perceive the image6as a three-dimensional image. Note that, the term three-dimensional image refers to an image that appears to be at a location that is different from the emission surface71of the display device10. The term three-dimensional image also includes a two-dimensional image perceived at a location away from the emission surface71of the display device10, for instance. In other words the term “three-dimensional image” does not refer only to an image perceived as having a solid shape, but also includes an image in two-dimensional form perceived at a different location than on the display surface of the display device10. In one or more embodiments of the present invention, the three-dimensional image6is an image of the character “A” in a plane200located on the positive side of the z axis from the emission surface71. The plane200is parallel to the xy plane.

The display device10is provided with a light guide plate70, a light source20, and a light-incidence tuning portion50. The light guide plate70is a transparent resin material with a relatively high index of refraction. The light guide plate70may be produced from, for instance, a polycarbonate resin (PC), a poly methyl methacrylate resin (PMMA), glass or the like.

The light guide plate70includes an emission surface71, and a rear surface72on the opposite side of the emission surface71. The light guide plate70also includes edges on the four sides thereof, i.e. a first edge73, a second edge74, a third edge75, and a fourth edge76. The second edge74is opposite the first edge73. The fourth edge76is opposite the third edge75. Light from the light source20enters the light guide plate70via the first edge73. The light guide plate70guides light from the light source20such that the light spreads out in planar form in a plane parallel to the emission surface71.

The rectangular coordinate system, and in particular the right-handed system of x axis, y axis, and z axis is used at some points to describe one or more of the embodiments. Here the z axis direction is a direction perpendicular to the emission surface71. The positive z axis direction is defined as the direction from the rear surface72to the emission surface71. The y axis direction is a direction perpendicular to the first edge73. The positive y axis direction is defined as the direction from the first edge73to the second edge74. The x axis direction is the direction perpendicular to the third edge75and the fourth edge76; and the positive x axis direction is defined as the direction from the third edge75to the fourth edge76. To avoid redundancy in the description, planes parallel to the xy, yz, and xz planes are sometimes referred to as the xy plane, yz plane, and the xz plane, respectively.

The light source20may include a light emitting diode (LED). Light from the light source20is adjusted by the light-incidence tuning portion50and enters the light guide plate70via the first edge73as incidence light.

A plurality of optical deflectors30is provided on the rear surface72of the light guide plate70located at mutually different positions. The plurality of optical deflectors30includes, for example, an optical deflector30a, an optical deflector30b, an optical deflector30c, and the like. The optical deflectors30may be provided two-dimensionally within the xy plane. For instance, the optical deflectors30may be provided as a matrix in the xy plane. Light guided by the light guide plate70enters the optical deflectors30.

The optical deflector30a, the optical deflector30b, and the optical deflector30ceach deflect light traveling through the light guide plate70and each causes the light exiting from the emission surface71to draw the three-dimensional image6. More specifically, the optical deflector30acauses the emission surface71to output light bound for various locations in the three-dimensional image6. The optical deflector30adeflects the light guided thereto by the light guide plate70such that the light spreads out in the xy plane and the yz plane and travels toward various locations in the three-dimensional image6.FIG. 1illustrates a state where light from the optical deflector30aspread out toward a number of locations in the three-dimensional image6. The optical deflector30band the optical deflector30calong with other optical deflectors30[in the optical deflector30] each behave identically. Each of the optical deflectors30fills a microscopic area on the rear surface72. Each of the optical deflectors30is a smaller surface area than when projected on the three-dimensional image6in the xy plane. The three-dimensional image6is created from the light spreading out from each optical deflector30among a multitude of optical deflectors30toward various locations in the three-dimensional image6. That is, the light from many optical deflectors30produces the light that radiates from the direction of the three-dimensional image6. Note that the light that creates the three-dimensional image6may be provided by at least three optical deflectors30that are not along the same straight line. That is, each of the optical deflectors30converts light entering therein into light with an intensity distribution according to the three-dimensional image6that spreads out two-dimensionally and exits from the emission surface. Thus, the light from the three or more optical deflectors30that are not on the same straight line forms the three-dimensional image6. The display device10is thereby able to project a three-dimensional image into a space. The display device10gathers the light beams from the plurality of optical deflectors30that are not on the same straight line to provide an observer with light beams that radiate from the three-dimensional image6. An observer is therefore able to perceive the three-dimensional image6regardless of whether the image is viewed from the x axis direction or the y axis direction.

FIG. 2schematically illustrates a cross section in the yz plane of the display device10;FIG. 3schematically illustrates one example of an optical element31included in an optical deflector30.

The light source20may include an LED21. A plurality of the LEDs21is arranged along the x axis direction. The optical axis of the light emitted from the LEDs21form an angle θ with the emission surface71. For example, the optical axis of the light emitted from the LEDs21may form a narrow angle θ of approximately 20° with the emission surface71. The light emitted from the LEDs21enters the light-incidence tuning portion50.

The light-incidence tuning portion50includes lenses51. The lenses51arranged along the x axis direction are respectively paired to an LED21in the plurality of LEDs21. Each of the lenses51reduces the spread of light traveling along the optical axis of the light emitted from the LED21corresponding thereto. The lenses51causes the light emitted from the LEDs21to approach parallel light. The lenses51may reduce the spread angle of the light emitted from the LEDs21in the xy plane. The lenses51may also reduce the spread angle of the light emitted from the LEDs21in the yz plane. Hereby, light approaching parallel light enters the light guide plate70.

Hereby the light beams within the xy plane guided by the light guide plate70and passing through locations in the light guide plate70spread out at an angle of predetermined value and advance from the locations in the light guide plate70about a direction connecting the locations in the light guide plate70and the light source20. In this disclosure, the light that spreads from a certain point when light beams pass through the certain point inside or outside the light guide plate and advances is considered to have been output from that point, and is simply referred to as “the spread of light” or the like. The angle of this spread of light is referred to simply as the “spread angle”. In a light intensity distribution along an angular direction, the spread angle may be the position at which the light intensity is half the maximum (full width at half maximum). The spread angle of light guided by the light guide plate70may be less than or equal to 5°. The spread angle of light may ideally be less than 1°. When projected onto the xy plane, the spread angle of the light may be less than or equal to 5° and ideally may be less than 1°. When projected onto the yz plane, the spread angle of the light may be less than or equal to 5° and ideally may be less than 1°.

As illustrated inFIG. 2andFIG. 3, the optical deflector30aincludes a reflection surface40a. The optical deflector30aalso includes reflection surface40a, reflection surface40b, reflection surface40c, reflection surface40d, and reflection surface40e. The reflection surface40is an example of an optical surface functioning as a deflection surface that deflects light. The reflection surface40a, reflection surface40b, reflection surface40c, reflection surface40d, and reflection surface40eare curved surfaces oriented in different directions. As above described, the optical axis of the LEDs21are inclined at an angle θ in the yz plane relative to the emission surface71. Therefore, even when the light entering the light guide plate70approaches parallel light, a greater amount of light is repeatedly reflected by and propagated between the emission surface71and the rear surface72in the light guide plate70compared to when the optical axis of incident light that is parallel to the y axis. Consequently, a greater amount of light strikes the reflection surface40compared to when the optical axis of incident light is parallel to the y axis.

The reflection surface40acauses light incident thereon to be emitted from the emission surface71at a different emission angle according to where the light is incident on the reflection surface40a. The reflection surface40acauses incident thereon to spread within an area61in the three-dimensional image6. In one or more embodiments of the present invention, the area61is an area parallel to the y axis. The light reflecting from the reflection surface40ais oriented from the reflection surface40atoward where the area61exists, and essentially no light reflected from the reflection surface40atravels toward where the area61does not exist. Accordingly, the light reflected from the reflection surface40ais substantially distributed only at angles within the yz plane from the reflection surface40atoward the area61. Thus, the reflection surface40amodulates the intensity of incident light in the yz plane in an angular direction and outputs said light. The reflection surface40ais a curved surface; therefore, the reflection surface40ais still capable of producing light that forms lines that create the image even when the light incident thereon is parallel light.

The reflection surface40breflects the light incident thereon spreading the light within an area62in the three-dimensional image6. The area62forms a portion of the character ‘A’ between an intersection point with the area61on the negative y axis and the furthest end point along the positive x axis. The reflection surface40creflects the light incident thereon spreading the light within an area63in the three-dimensional image6. The area63forms a portion of the character ‘A’ between an intersection point with the area61on the positive y axis and the furthest end point along the positive x axis. The reflection surface40dreflects the light incident thereon spreading the light within an area64in the three-dimensional image6. The area64forms a portion of the character ‘A’ between an intersection point with the area61on the negative y axis and the furthest end point along the negative x axis. The reflection surface40ereflects the light incident thereon spreading the light within an area65in the three-dimensional image6. The area65forms a portion of the character ‘A’ between an intersection point with the area61on the positive y axis and the furthest end point along the negative x axis. Because the reflection surface40b, the reflection surface40c, the reflection surface40d, and the reflection surface40eare all curved, each of the reflection surfaces40is capable of producing light that forms lines that create the image even when the light incident thereon is parallel light.

Thus, the reflection surface40aspreads light incident thereon having an intensity distribution according to at least the image of the area61along the z axis, and causes emission of said light. The reflection surface40bspreads light incident thereon having an intensity distribution according to at least the image of the area62along the x axis, and causes emission of said light. The reflection surface40cspreads light incident thereon having an intensity distribution according to at least the image of the area63along the x axis, and causes emission of said light. The reflection surface40dspreads light incident thereon having an intensity distribution according to at least the image of the area64along the x axis, and causes emission of said light. The reflection surface40espreads light incident thereon having an intensity distribution according to at least the image of the area64along the x axis, and causes emission of said light. Thus, the optical deflector30apossesses a plurality of reflection surfaces that reflect light towards lines in the three-dimensional image6where the optical deflector30amodulates the intensity of incident light two dimensionally or in two directions according to the three-dimensional image6, and causes emission of said light from the emission surface71. Hereby, a single optical deflector30aprovides light beams that pass through substantially the entire three-dimensional image6.

The optical deflector30bincludes a reflection surface41b. Similar to the reflection surface40a, the reflection surface41bcauses light incident thereon to be emitted from the emission surface71at a different emission angle according to where the light is incident on the reflection surface41a. More specifically, the light reflecting from the reflection surface41bspreads within an area61in the three-dimensional image6.FIG. 3only illustrates the reflection surface40aand the reflection surface41b; however, each of these optical deflectors30includes a reflection surface that spread the incident light within the area61. Each of the optical deflectors30includes a plurality of reflection surfaces that reflect light toward lines within the three-dimensional image6similarly to the optical deflector30a. Each of the optical deflectors30modulates the intensity of the light incident thereon two-dimensionally or in two directions, and causes emission of said light from the emission surface71. Thus, each of the optical deflectors30provides light beams that pass through substantially the entire three-dimensional image6.

The light emitted from the emission surface71is actually refracted within the emission surface71. Therefore, the optical deflector30is designed to take into account the refraction within the emission surface71. However, for the sake of simplicity, the description of one or more embodiments of the present invention is made as if there were no refraction in the emission surface71.

FIG. 4schematically illustrates the optical deflector30providing light that travels toward a specific observation point. For instance the light forming the area62is provided from a specific reflection surface in the optical deflector30e, and a specific reflection surface in the optical deflector30f, while no light is provided from the optical deflector30dand the optical deflector30g. Thus, a specific portion in the three-dimensional image6is created by specific portions of a specific optical deflector30of the plurality of optical deflectors30when the three-dimensional image is viewed from a specific observation position.

The display device10is configured such that each of the optical deflectors30established two-dimensionally in the xy plane provide light that passes though all portions/sites in the three-dimensional image6. Therefore, the three-dimensional image may be viewed from a wide range. Because the display device is also capable of presenting light from a specific location in the xy plane that passes through sites throughout the three-dimensional image6, the three-dimensional image is formed as a plane and not a point.

FIG. 5is a perspective view that schematically illustrates an optical deflector30A as a modified example of the optical deflector30. The optical deflector30A possesses an entirely convex reflection surface. The optical deflector30A is provided on the rear surface72of the light guide plate70. The convex reflection surface of the optical deflector30A deflects the light guided through the light guide plate70so that the light beams passing through the plane200which includes the three-dimensional image exit from the emission surface71.

The portions of the optical deflector30A that do not correspond to creating the character ‘A’ are provided with an anti-reflective film110. The light entering at portions where the anti-reflective film110is formed on the optical deflector30A does not substantially reflect. The light entering at portions with no anti-reflective film110formed on the optical deflector30A are reflected. Thus, the optical deflector30A deflects light entering therein so that the light beams passing through the character ‘A’ of the three-dimensional image6exit from the emission surface71. The anti-reflective film110may be produced, for instance, by coating areas of the rear surface72that do not correspond to the area forming the character ‘A’ with black paint material. The anti-reflective film110may be produced by printing areas that do not correspond to the area forming the character ‘A’ with black paint material. Because the optical deflectors30A may be created by printing the black paint material after forming the convex portion on the light guide plate70, this simplifies the process of producing the optical deflector.

FIGS. 6A and 6Bschematically illustrate an optical deflector30B as an example for modifying the optical deflector30.FIG. 6Ais a perspective view of the optical deflector30B, andFIG. 6Bis a view of a portion C-C along a cross section in the yz plane. The optical deflector30B possesses a plurality of reflection surfaces120created in a local region that corresponds to the character ‘A’. Note that no reflection surfaces are formed in areas outside the local region corresponding to the character ‘A’. The light entering at portions where no reflection surfaces120are formed on the optical deflector30B does not substantially reflect. Whereas, the optical deflector30B deflects light entering the portions where the reflection surfaces120are formed so that the light beams passing through three-dimensional image6exit from the emission surface71.

FIG. 7schematically illustrates an optical deflector30C as an example for modifying the optical deflector30. The optical deflector30C includes a plurality of optical elements31C provided different locations. The optical elements31C each possess a single flat reflection surface. The reflection surface included in each of the optical elements31C reflect light incident thereon to mutually different points in the three-dimensional image6.

The optical elements31may all be provided separately, or may be provided where a portion thereof are connected. The distribution pattern for the optical elements31may be different in accordance with the location at which optical deflectors30are provided.

FIG. 8Aschematically illustrates optical deflectors30D as an example for modifying the optical deflector30; the plurality of reflection surfaces may be formed evenly as a whole on the rear surface72of the light guide plate70.

The rear surface72is also provided with an optical component140. The optical component140is produced from material having substantially the same refractive index as a light guide plate70. The optical component140possesses an optical surface facing the rear surface72that connects with the reflection surfaces formed on the rear surface72. The optical component140is formed at regions on the rear surface72outside of regions that do not correspond to the character ‘A’ in the three-dimensional image6, and is not provided at regions corresponding to the character ‘A’ in the three-dimensional image6. The reflection surfaces formed on the rear surface72in the sections where no optical component140is provided serve as the optical deflector30D.

The light incident at the regions of the rear surface72connected to the optical component140pass through the rear surface72. That is, the light incident at regions at the regions of the rear surface72connected to the optical component140is not deflected in a direction allowing the light to exit from the emission surface71. Whereas, the light incident at regions on the rear surface72not connected to the optical component140are deflected and exit from the emission surface71, becoming light beams that pass through locations in the three-dimensional image6.

FIG. 8Bschematically illustrates optical deflectors30E as an example for modifying the optical deflector30; the plurality of reflection surfaces may be formed as a whole on the rear surface72of the light guide plate70.

The rear surface72is also provided with an optical component170. The optical component170is produced from material having substantially the same refractive index as a light guide plate70. The optical component170possesses an optical surface facing the rear surface72that connects with the reflection surfaces formed on the rear surface72. A reflective film160is provided in regions of the optical component170corresponding to the character ‘A’ in the three-dimensional image6. No reflective film is provided at regions outside regions corresponding to the character ‘A’. The reflection surfaces formed on the rear surface72outside the sections connecting to the reflective film160of the optical component170serve as the optical deflector30E.

The light incident at the regions of the rear surface72connected to the reflective film160pass through the rear surface72. That is, the light incident at the regions of the rear surface72unconnected to the reflective film160is not deflected in a direction allowing the light to exit from emission surface71. Whereas, the light incident at regions on the rear surface72connected to the reflective film160are deflected and exit from the emission surface71, becoming light beams that pass through locations in the three-dimensional image6. The reflective film160may be vapor-deposited silver film, vapor-deposited aluminum film, silver plated film, chrome plated film, or the like. The reflectance of the reflective film160in each of the optical deflectors30E may be mutually different in accordance with the location of the corresponding image. Hereby it is possible to produce an image with varied luminance. The reflective film160may also selectively reflect a specific color. Hereby it is possible to produce a color image. The color of light selectively reflected by the reflective film160in each of the optical deflectors30E may be mutually different in accordance with the location of the corresponding image. Hereby it is possible to produce a multi-colored image. Note that the light guide plate70and the optical component170may be considered a single light guide plate. In this case, the plurality of optical deflectors30is provided inside the light guide plate70.

FIG. 8Cschematically illustrates optical deflectors30F as an example for modifying the optical deflector30. An optical component190is provided on regions of the rear surface72of the light guide plate70corresponding to the character ‘A’ in the three-dimensional image6. The optical component190includes a plurality of reflection surfaces on the other side from the surface thereof connected to the rear surface72. The light incident on the optical component190are deflected by the plurality of reflection surfaces and exit from the emission surface71, becoming light beams that pass through locations in the three-dimensional image6.

FIG. 9,FIG. 10A,FIG. 10B, andFIG. 10Care for describing a technique for producing the optical deflector30G as an example of modifying the optical deflector30A; a portion of a Fresnel lens serves as the optical deflector30G.

The optical surfaces forming the Fresnel lens are provided on the rear surface72of the light guide plate70for each optical deflector30.FIG. 10AandFIG. 10Billustrates when a Fresnel lens is created for a single optical deflector30G. The Fresnel lens in each of the optical deflectors30deflects light guided through the light guide plate70so that the light beams passing through the plane200which contain the three-dimensional image exit from the emission surface71.

Next, as illustrated inFIG. 10C, an anti-reflective film210is created on the rear surface72of the light guide plate70in regions outside the regions corresponding to the character ‘A’ in the three-dimensional image6. For example, the anti-reflective film210may be produced by printing black paint material in regions outside the regions corresponding to the character ‘A’ in the three-dimensional image6. Hereby, only the light incident in some regions of the Fresnel lens corresponding to the character ‘A’ are substantially deflected to create light beams that pass through locations in the three-dimensional image6and exit from the emission surface71. Because the optical deflectors30may be created by printing the black paint material after forming the optical surfaces of the Fresnel lens on the light guide plate70, this simplifies the process of producing the optical deflector.

FIG. 11schematically illustrates a display device10A as an example of modifying the display device10. The display device10A projects a virtual three-dimensional image in a space opposite the emission surface71. This example supposes that the three-dimensional image is located in a plane240parallel to the emission surface71.

FIG. 11illustrates a first reflection surface42kand a second reflection surface42bbelonging to mutually different optical deflectors30. The area61A inFIG. 11is one of the lines forming the three-dimensional image. For instance, the area61A may correspond to the area61into three-dimensional image6.

The reflection surface42adeflects the light incident thereon at a different angle in accordance with the location of incidence, and the light exits from the emission surface71. More specifically, the reflection surface42aorients light toward an area66symmetrical to the area61A relative to the reflection surface42aand causes the light to then exit from the emission surface71. For instance, the reflection surface42areflects the light incident thereon in the direction of a line connecting an end point in the negative y axis direction of the area62and the point at which the light is incident. Additionally, the reflection surface42areflects the light incident thereon in the direction of a line connecting an end point in the positive y axis direction of the area62and the point at which the light is incident. Thus, the reflection surface42asupplies light beams connecting any desired point in the area61A and the reflection surface42a. The reflection surface42ahereby provides light beams identical to the light beams emanating from the area61A. The reflection surface42asimilarly provides light beams connecting any desired point in the area61A and the reflection surface42a. Thus, the reflection surface for the optical deflector merely needs to be formed to reflect emission light toward a location where the image is symmetrical to the optical deflector to create an image in the space opposite the emission surface71. Additionally, when creating a three-dimensional image in the space near the rear surface72, light from three or more optical deflector which output light with an intensity distribution in accordance with the three-dimensional image near the rear surface72may be used to create light that spreads from the three-dimensional image near the rear surface72similarly to creating the three-dimensional image6in the space near the emission surface71. Thus, the display device10A gathers light beams from the two-dimensionally arranged plurality of optical deflectors to supply light beams that radiate from the three-dimensional image near the rear surface72in a space near an observer.

The above provides a description of the cases where the display device10and the display device10A present an image that is formed within a plane parallel to the emission surface71. However, the location of the three-dimensional image is not limited to a within a plane parallel to the emission surface71.

Again, the optical deflectors30may be provided as a matrix in the xy plane as above described. For instance, the optical deflectors30may be provided at equal pitch in the x axis direction and at equal pitch in the y axis direction. The pitch of the optical deflectors30in the x axis direction may be the same or different from the pitch in the y axis direction. The pitch of the optical deflectors30may be smaller in the x axis direction than in the y axis direction. The density of the points in the x axis direction in the three-dimensional image6increases when the pitch of the optical deflectors30is smaller in the x axis direction than in the y axis direction. Therefore, the plurality of points forming the three-dimensional image6are connected along the x-axis direction allowing those points to be more easily perceived as a line. Hereby, an observer can easily recognize both ends of the line and more easily perceive the form of the three-dimensional image6.

The pitch of the optical deflectors30may be varied within the xy plane. Varying the pitch of the optical deflectors30in the xy plane makes it possible to modify the resolution of the three-dimensional image6in each region. Additionally, the optical deflectors30need not be provided regularly. The optical deflectors30may be provided randomly within the xy plane. In order for an observer to perceive the display device10is transparent, the pattern density of the optical elements31according to one or more embodiments of the present invention is 50% or less. Additionally, the pattern density of the optical elements31according to one or more embodiments of the present invention is 10% or less.

FIG. 12Aschematically illustrates an example of distributing the optical deflectors30in strips. While in this example the optical deflectors30form lines in the x axis direction and in the y axis direction, the optical deflectors30have a smaller pitch in the x-axis direction than the pitch of the optical deflectors30in the y-axis direction.

FIG. 12Bschematically illustrates an example of distributing the optical deflectors30in a zigzag pattern. For example, taking the x-axis direction as a row, the pinch of the optical detectors30in each row is identical. The positions of the optical deflectors30adjacent in the y-axis direction between rows are shifted in the x-axis direction. For example, the optical deflectors30between adjacent rows may be shifted in the x-axis direction by half the pitch between the optical deflectors30along a row.

FIGS. 13A and 13Bschematically illustrate various examples for the shape of the optical element31;FIG. 13Ais a perspective view of an optical element31, andFIG. 13Billustrates when the reflection surface40is projected onto the xy plane. When the reflection surface40is projected onto the xy plane, the outer shape in positive y axis direction and the outer shape toward the negative y axis direction which outline the reflection surface40are concentric arcs. The outer shape in the negative y axis direction of the reflection surface40projected onto the xy plane may be referred to as the front outline while the outer shape toward the positive y axis direction is referred to as the rear outline. The front outline and the rear outline of the reflection surface40form concentric arcs.

If cut along a plane parallel to the zy plane, the line of intersection between the optical element31illustrated inFIG. 13AandFIG. 13Band the reflection surface40is a straight line. However, because the front outline and the rear outline are curved, the reflection surface40inFIGS. 13A and 13Bis a curved surface. Therefore, a single reflection surface40can present the light needed to create a line or a plane forming at least a portion of the image.

FIGS. 14A, 14B, and 14Cschematically illustrate various examples for distributing the optical elements31in the xy plane.FIG. 14Aillustrates an example where a plurality of optical elements31forms a line along the y axis direction.FIG. 14Bis a modified version of the example inFIG. 14A, and illustrates an example where the optical elements31are distributed so that when the optical elements31lined up in the y axis direction are viewed in order, the same shifted along the x axis direction by a fixed offset.FIG. 14Cillustrates an example where the optical elements31are distributed continuously as a single element along the x axis direction. InFIG. 14Cthe end portions of optical elements adjacent in the x axis direction are connected to provide a single optical element. The dashes inFIG. 14Ccorrespond to the end ports of adjacent optical elements in the x axis direction.

FIGS. 15A and 15Bschematically illustrate other example shapes for the reflection surface of the optical element31;FIG. 15AandFIG. 15Bdepicts the shape of the reflection surface40projected onto the xy plane. The reflection surface40illustrated inFIG. 15Ahas a shape that includes reflection portions connected along the x axis direction. In one reflection portion the front outline and the rear outline are concentric arcs with a first curvature, and in another reflection portion the front outline and the rear outline are concentric arcs with a second curvature. As can be seen inFIG. 15Bthe front outline and a rear outline forming the concentric arcs outlining the reflection surface40are partitioned to provide a reflection surface40separated into a plurality of sections. The reflection surface whose front outline and rear outline are concentric arcs is partitioned whereby the reflection surface40depicted inFIG. 15Bis separated into a plurality of sections.

FIGS. 16A and 16Bschematically illustrate other example shapes for the reflection surface of the optical element31.FIG. 16Ais a perspective view of an optical element31, andFIG. 16Billustrates when the reflection surface40of the optical element31is projected onto the xy plane. The optical element31is created from three planes with mutually different normal line directions. When the reflection surface40is projected onto the xy plane, each of the front outlines and the rear outlines form three polygonal lines that extend in different directions. Because the reflection surface40illustrated inFIGS. 16A and 16Bis flat, light entering each of the reflection surfaces40are oriented in three mutually different directions. Therefore, the optical element31illustrated inFIGS. 16A and 16Bcan present light that creates three points which are a portion of the image.

FIGS. 17A, 17B, and 17Cschematically illustrate other example shapes for the reflection surface of the optical element31. The reflection surfaces40in the optical element31illustrated inFIG. 17AandFIG. 17Bdiffer from the optical element31illustrated inFIG. 13A; that is, the ridge of the reflection surface40toward the positive z axis has different heights in the z-axis direction. When projected onto the xz plane, the ridge of the reflection surface40toward the positive z axis changes continually along the x axis direction When cut along a plane parallel to the yz plane the linear length of the reflection surface40changes along the x axis direction. The intensity of light reflected from the reflection surface40therefore changes along the x axis direction. Consequently, the optical element31illustrated inFIG. 17AandFIG. 17Bcan present light for creating an image of lines where the luminance thereof changes along the x direction.

FIG. 17Cschematically illustrates various examples for distributing the optical elements31in the xy plane. Each of the optical elements31includes a plurality of optical elements that are curved reflection surfaces where the front outline in the rear outline form concentric arcs (e.g., reflection surface41a), and optical elements that are flat reflection surfaces (e.g., reflection surface41b). The optical elements that are flat reflection surfaces can provide reflection light of higher intensity per surface area than the optical elements with curved reflection surfaces. Thus, distributing the kind of optical elements illustrated inFIG. 17Ccan increase the intensity of light output from the flat reflection surface in a particular direction. Hereby it is possible to provide light that creates an image having a point with a relatively high luminance. The optical elements31illustrated inFIG. 17A,FIG. 17B, andFIG. 17Cspread light incident thereon with an intensity distribution that changes continuously or gradually in the angular direction, and causes said light to exit from the emission surface71.

FIGS. 18A, 18B, and 18Care for describing the difference in emission light intensity due to the surface area of the reflection surface40.FIG. 18Aillustrates when the reflection surface40is projected onto the xy plane. The three reflection surfaces illustrated inFIG. 18Ahave outer shapes with mutually different curvatures, and mutually different lengths in the y axis direction. The length in the y axis direction is proportional to the length of a straight line intersecting a plane parallel to the yz plane and the reflection surface40. The amount of emission light increases as the length of the straight line intersecting a plane parallel to the yz plane and the reflection surface40increases. As illustrated inFIG. 18A, taking the amount of emission light of a reference reflection surface as 1, a reflection surface with an intersecting line double the length of the reference reflection surface, obtains double the amount of emission light, and the location on the image corresponding thereto also has double the luminance. Additionally, a reflection surface with an intersecting line quadruple the length of the reference reflection surface, obtains four times the amount of emission light, and the location on the image corresponding thereto also has four times the luminance. Thus, the luminance of an image may be modified for each region in the image via optical elements having reflection surfaces with intersecting lines of different lengths. More generally, at least n-levels of presentation is possible by way of a plurality of optical elements with n types of intersecting line lengths. Further, 2n-levels of presentation is possible by combining a plurality of optical elements where the intersecting lines are the power of any desired cardinal number (e.g., 2) with n types of intersecting line lengths, where. Here, n is any positive value greater than or equal to 2. The reflection surfaces40with different surface areas as illustrated inFIGS. 18A, 18B, and 18Cmay be used to spread light incident thereon with an intensity distribution that changes continuously or gradually in the angular direction, and cause said light to exit from the emission service71. Note that a plurality of light guide plates capable of providing multi-tonal display may be used where light of mutually different colors (e.g., three colors: red, blue, and green) may enter the light guide plates to accomplish color display.

FIG. 18Billustrates an example of distributing the reflection surfaces to adjust the amount of emission light by combining a plurality of reflection surfaces where the length of the intersecting lines are different. For example, an amount of emission light of 3 can be obtained by combining reflection surfaces where the amount of emission light is 1 and 2 respectively. The luminance of the corresponding section in the image can thus be tripled by ensuring that the light from this combined reflection surface exits toward the same position or near the position in the image. As illustrated inFIG. 18AandFIG. 18B, the combination of three optical elements with intersecting lines of different lengths makes it possible to present eight levels of gradation.

FIG. 18Cdepicts the height h of a perpendicular line drawn from an edge of the reflection surface40in the positive the direction down to the xy plane. Varying the heights of the reflection surfaces also varies the amount of emission light.

Note that the light-incidence tuning portion50with lenses51in the display device10makes it possible to obtain incident light with a small spread angle. A light source capable of outputting light satisfying the above described spread angle may be used without providing the light-incidence tuning portion50. The aforesaid light source may be a laser light source, such as a laser diode, or the like. Additionally, a single LED21may be used as a light source; the radiation pattern of the light from the single LED21may be extended out to obtain light satisfying the above described spread angle. The emission window of the LED21may also be narrowed to obtain light satisfying the above described spread angle. A light guide plate having an emission surface facing the first edge of the light guide plate70may be placed between the LEDs or the like of a single light source and the first edge73to have a light emitted from said light guide plate enter the first edge73.

FIG. 19schematically illustrates a light guide plate53and lens51as an example of modifying the light-incidence tuning portion50. Light from the LED21is rendered substantially parallel in a direction along the x axis direction by the lens51, and enters the light guide plate53. Light entering the light guide plate53propagates in a direction along the x axis. The emission surface of the light guide plate53is provided facing the first edge73. The light that travels through the light guide plate53is reflected by a plurality of reflection surfaces formed on a portion of the surface opposite emission surface of the light guide plate53; the reflected light exits from the emission surface of the light guide plate53in the xy plane as at substantially parallel light beams. Thus, light beams parallel to the y axis direction enter the light guide plate70from the first edge73. Hereby, the light guide plate70may propagate light with a small spread angle through the xy plane and the yz plane.

Note that the above describes a configuration that uses incident light which is substantially parallel to the y axis direction in order to have light with a small spread angle in the xy plane and the yz plane in the light guide plate70. There other configurations for creating light with a small spread angle in the xy plane and the yz plane; for instance, a configuration using a light source20with substantially a single point light source, and a light-incidence tuning portion50that reduces the spread of the light from said light source within the yz plane. In this case, the light-incidence tuning portion50may be a cylindrical convex lens that protrudes in at least one of the positive y axis direction or the negative y axis direction within the yz plane.

FIG. 20schematically illustrates a display device10B as an example of modifying the display device10, along with a three-dimensional image6; andFIG. 21is a plan view of the display device10B in the xy plane. The display device10B projects a three-dimensional image6B onto a plane300parallel to the xz plane.

Compared to the display device10, the light traveling in the light guide plate70in the display device10B has a wider spread in the yz plane. As is later described, the light-incidence tuning portion50B reduces the spread angle of light from the light source20within the xy plane, similarly to the light-incidence tuning portion50. However, the light-incidence tuning portion50B does not reduce the spread angle of the light from the light source20in the yz plane. The light-incidence tuning portion50B does not substantially affect the spread angle of the light from the light source20in the yz plane. For example, the lens51B in the light-incidence tuning portion50B is a convex cylindrical lens that is curved in the xy plane and has substantially has no curve in the yz plane. The lenses51are cylindrical lens with curvature in both planes. The spread angle of the light entering the light guide plate70is greater when projected onto the yz plane than when projected onto the xy plane. The beam spread angle of light guided by the light guide plate70when projected onto xy plane may be 5° or less. According to one or more embodiments of the present invention, the beam spread angle of the light in the xy plane is less than 1°. Another method of reducing the beam spread angle of the light within the xy plane of the light guide plate70may involve adopting a single light source, e.g., an LED, as the light source20, and adopting a mask with a window smaller than a predetermined weight in the x axis direction as the light-incidence tuning portion50B.

The display device10B has a plurality of optical deflector groups including an optical deflector group330a, an optical deflector group330b, and an optical deflector group330c. The optical deflector groups330include a plurality of optical deflectors provided along a direction parallel to the x axis. For example, the optical deflector group330ahas a plurality of optical deflectors30including an optical deflector30Ba. The optical deflector group330balso has a plurality of optical deflectors including an optical deflector30Bb. The optical deflector group330balso has a plurality of optical deflectors including an optical deflector30Bc.

The optical deflector30Ba deflects the light incident thereon causing the light to spread in a direction parallel to the xy plane, and causing the light to exit from the emission surface71. The light beams output from the emission surface71due to the optical deflector30Ba intersect the plane300as a line for the most part. As illustrated inFIG. 20andFIG. 21, two light beams are output from the emission surface71due to the optical deflector30Ba. The two light beams output intersect the plane300at a line351and a line352. As illustrated inFIG. 21, any of the optical deflectors included in the optical deflector group330acause the emission surface71to output light beams that intersect the plane300at the line351and the line352, similarly to the optical deflector30Ba. The line351and the line352exist for the most part in a plane parallel to the xy plane and form a portion of the three-dimensional image6. Thus, the light from the numerous optical deflectors30belonging to the optical deflector group330acreates an image of the line351and the line352. The light producing the image of the line351and the line352may be provided by at least two optical deflectors30set at different locations along the x axis direction. That is, each of the optical deflectors30belonging to the optical deflector group330aspreads the light incident thereon that has an intensity distribution corresponding to the line351and the line352; the light is spread in the x axis direction within a plane parallel to the emission surface71and caused to exit from the emission surface71. Hereby, light from the plurality of optical deflectors30belonging to the optical deflector group330aarranged along the x axis direction becomes light that forms an image at the line351and the line352.

The optical deflector30Bb deflects the light incident thereon causing the light to spread in a direction parallel to the xy plane, and causing three light beams to exit from the emission surface71. The three light beams output intersect the plane300at a line361, a line362, and a line363. Any of the optical deflectors included in the optical deflector group330bmay cause the emission surface71to output light beams that intersect the plane300at the line361, the line362, and the line363. Thus, each of the optical deflectors30belonging to the optical deflector group330bspreads the light incident thereon that has an intensity distribution corresponding to the line361, the line362, and the line363; the light is spread in the x axis direction within a plane parallel to the emission surface71and caused to exit from the emission surface71. Hereby, light from the plurality of optical deflectors30belonging to the optical deflector group330barranged along the x axis direction becomes light that forms an image at the line361, the line362, and the line363. The line361, the line362, and the line363exist for the most part in a plane parallel to the xy plane and form a portion of the three-dimensional image6B. The line361, the line362, and the line363, and the line351and the line352are at different locations along the z axis within the plane300.

The optical deflector30Bc deflects the light incident thereon causing the light to spread in a direction parallel to the xy plane, and causing three light beams to exit from the emission surface71. The two of the light beams output intersect the plane300at a line371and a line372. Any of the optical deflectors included in the optical deflector group330cmay cause the emission surface71to output light beams that intersect the plane300at the line371and the line372. Each of the optical deflectors30belonging to the optical deflector group330cthus spreads the light incident thereon that has an intensity distribution corresponding to the line371and the line372; the light is spread in the x axis direction within a plane parallel to the emission surface71and caused to exit from the emission surface71. Hereby, light from the plurality of optical deflectors30belonging to the optical deflector group330carranged along the x axis direction becomes light that forms an image at the line371and the line372. The line371and the line372exist for the most part in a plane parallel to the xy plane and form a portion of the three-dimensional image6. The line371and the line362, and the line351and the line352are at different locations along the z axis within the plane300. The line371and the line372, the line361, and the line362and line363are at different locations along the z axis within the plane300.

Thus, the display device10B gathers light beams from the two-dimensionally arranged plurality of optical deflectors to present light beams that radiate from the image6B in the space near an observer. Therefore, an observer can perceive the three-dimensional image6B from a wide range of positions along the x axis direction.

FIG. 22schematically illustrates a three-dimensional image6B projected by the display device10B onto a plane300. In this manner, light from the plurality of optical deflector element groups in the display device10B produce a plurality of lines at mutually different locations in the z axis in the plane300wherein the three-dimensional image6B is created. The plurality of lines in the plane300due to the light beams from the plurality of optical deflector element groups create the three-dimensional image6B.

The optical deflectors30may be provided regularly or irregularly in the display device10B similarly to the display device10. The pitch of the optical deflectors30may be varied in each region in the x axis direction to thereby vary the luminance in the three-dimensional image6B. Another method of adjusting the luminance may involve varying the size of the optical surface of the optical deflectors30in each region. For example, the luminance in each region may be modified by varying at least one of the height or the length of the optical surface included in the optical deflector30. The display device10B may be afforded eight levels of luminance whereby monochrome or eight-tone single color display is possible. Note that three light guide plates capable of providing eight-tone multi-tonal display may be used where, light of mutually different colors (e.g., three colors: red, blue, and green) may enter the light guide plates to accomplish a full-color display.

The luminance of the image produced via a single optical deflector group330is proportional to the amount of light from the optical deflectors30available within a unit angle in the xz plane from the location at which the image is formed. Assuming that the amount of light output from each of the optical deflectors30is the same, the luminance of the image formed is proportional to the number of optical deflectors30available within a unit angle. Accordingly, to create an image with a uniform luminance, according to one or more embodiments of the present invention, the pitch of the optical deflectors30in the x axis direction increases as the distance between the location of the image corresponding to each of the optical deflectors30and the z axis direction increases. For example, according to one or more embodiments of the present invention, the pitch of the optical deflectors30belonging to the optical deflector group330acorresponding to the line351and the line352is greater than the pitch of the optical deflectors30belonging to the optical deflector groups330corresponding to lines located closer to the light guide plate70than the line351or the line352(e.g., optical deflector group330b, optical deflector group330c, or the like), the pitch of the optical deflectors30belonging to the optical deflector groups330belonging to each of the optical deflector groups330may be proportional to the distance between the location of the line produced by light from each of the optical deflectors30and the light guide plate70in the z axis direction. Hereby, the number of optical deflectors30available within a unit angle can be the same when viewed from a location where the image is formed; therefore, this prevents large differences in light intensity of the image due to the location of the image along the z axis direction.

FIG. 23Aschematically illustrates an example shape of an optical surface of the optical deflector30Bb projected onto the xy plane. The optical deflector30Bb includes an optical surface380aand an optical surface380bwhich provide the outer shape of an arc. The optical surface380aand the optical surface380bspread light incident thereon in the xy plane. The optical surface380aand the optical surface380bare separated. The area separating the optical surface380aand the optical surface380bcorrespond to a section of the three-dimensional image6B with no lines.

The optical surface380aand the optical surface380bmay be connected. The curvature of the outer shape of the optical surface380amay differ from the curvature of the outer shape of the optical surface380b. Additionally, the three-dimensional image6B may have varied brightness along the x axis direction; here the length of the line intersecting the optical surfaces380and the yz plane may be varied in the x axis direction. For instance, the height of the optical surfaces380may be varied. There may also be a plurality of optical surfaces380producing the same line.

A planar image may be formed with a collection of connecting lines as illustrated inFIG. 22; an optical component may include optical surfaces380having curved reflection surfaces as illustrated inFIG. 23, whereby an even smaller number of optical components may be used to supply the light that produces a planar image.

A modified version of the optical deflector30Bb may include an optical component having an optical surface;FIG. 24Aschematically illustrates an example shape of the optical surface projected onto the xy plane.FIG. 24Bschematically illustrates a three-dimensional image350projected onto the plane300by the modified version of the optical deflector. In this modification example, the image includes four planar optical surfaces: an optical surface360a, an optical surface360b, an optical surface360c, and an optical surface360d. The optical surface360a, the optical surface360b, the optical surface360c, and the optical surface360dare linear prisms. The optical surfaces360intersect the rear surface72of the light guide plate70as lines.

The optical surfaces360reflect light incident thereon. Because the optical surfaces360are flat, the light reflected from the optical surfaces360in intersect the plane300at substantially a point. More specifically, the light from the optical surface360aintersects the plane300at substantially the point370a; the light from the optical surface360intersects the plane300at substantially the point370b; the light from the optical surface360cintersects the plane300at substantially the point370c; and the light from the optical surface360dintersects the plane300at substantially the point370d. Thus, the points370where light from the optical surfaces intersects the plane300are mutually different. In this modification example, the light beams forming a plurality of points that produce an outline of the three-dimensional image6B the output from the pension surface71.

The four optical surfaces360are provided continuing along the x-axis direction in this modification example. Therefore, the intersecting line for this optical component and the xy plane are polygonal lines. As illustrated inFIG. 24AandFIG. 24B, a plurality of groups of flat reflection surfaces are required for the optical deflectors30in order to produce an image from any line.

Note that optical surfaces360do not need to be connected. A portion of the optical surfaces360may be connected, or all the optical surfaces360may be separated. For example, an optical component having three connected optical surfaces360and an optical component having a single optical surface360may be provided separately as illustrated inFIG. 24B. As another example, an optical component having two connected optical surfaces360and an optical component having two optical surfaces360may be provided separately. As yet another example, an optical component having two connected optical surfaces360, an optical component having a single optical surface360, and another optical component having a single optical surface360may be provided separately from each other.

A modified version of the optical deflector30Bb may include an optical component having an optical surface;FIG. 25Aschematically illustrates an example shape of the optical surface projected onto the xy plane.FIG. 25Bschematically illustrates a three-dimensional image400projected onto the plane300by the modified version of the optical deflector. In addition to the configuration of the optical deflector30Bb described in relation toFIG. 23A, and the like, this modification example includes the configuration of the four optical surfaces360described pertaining toFIG. 24A. This modification example can create outlines of the three-dimensional image6B in addition to the three-dimensional image6B. Therefore, it is possible to emphasize the outline of the three-dimensional image6B. Hereby, an observer is able to clearly recognize the shape of the three-dimensional image6B.

FIG. 25Cschematically illustrates an example shape of a modified version of the optical deflector30Bb projected onto the xy plane.FIG. 25Cis equivalent to moving the linear prisms constituting the optical surfaces360to the ends of the arc shaped prisms constituting the optical surfaces380. More specifically, the optical surface360ais provided at the end portion of the optical surface380atoward the negative x axis direction; the optical surface360bis provided at the end portion of the optical surface380atoward the positive x axis direction; The optical surface360cis provided at the end portion of the optical surface380btoward the negative x axis direction; and the optical surface360dis provided at the end portion of the optical surface380btoward the positive x axis direction. In this manner, the optical surfaces360responsible for producing the outline of the three-dimensional image at both ends of each optical surface380along the x axis. Although the end portions of the optical surfaces380and the end portions of the optical surfaces360are connected in this modification example, the end portions of the optical surfaces380and the end portions of the optical surfaces360may be separate.

FIG. 26Aschematically illustrates where a drip440may be created on the optical surface380; the drip440may form when creating the optical surfaces380on the light guide plate70. The spread angle of the light guided by the light guide plate70usually tends to increase with a large difference in the orientation of the surface with a drip and the orientation of the surface with no drip.

As illustrated inFIG. 26A, the outer shapes of the optical surfaces380are arcs in the xy plane with the center of curvature closer to the light source than the optical surfaces380. Therefore, the normal line direction450from a surface of the drip440on the optical surfaces380differs slightly from the normal line direction460from a surface with no drip on the optical surfaces380.

FIG. 26Bschematically illustrates an intensity distribution in the x direction for light beams from the optical surfaces380. As illustrated inFIG. 26B, the distribution470of light beams from a section with no drip on the optical surfaces380lies largely over the distribution480of light beams from the drip440. Therefore, the drip440hardly affects the spread of the light beams from the optical surfaces380.

FIG. 26Cschematically illustrates and optical surface382where the center of curvature of the contour is opposite the light source20relative to the optical surface. In this case, the normal line direction452from a surface of the drip442differs greatly from the normal line direction462from a surface with no drip on the optical surfaces382.

FIG. 26Dschematically illustrates an intensity distribution in the x direction for light beams from the optical surfaces380. As illustrated inFIG. 26D, one portion of the distribution482of the light beams from the drip442falls outside the distribution472from the section with no drip on the optical surfaces380. Therefore, the drip442greatly affects the spread of the light beams from the optical surfaces380. As above described, according to one or more embodiments of the present invention, the center of curvature of the optical surfaces380are closer to the light source20.

FIG. 27schematically illustrates a display device10C as an example of modifying the display device10B; the display device10C projects a virtual three-dimensional image in a space opposite the emission surface71. This example supposes that the three-dimensional image is located in a plane500orthogonal to the emission surface71.

The display device10B has a plurality of optical deflector element groups including an optical deflector group330Ca, an optical deflector group330Cb, and an optical deflector group330Cc.

The optical deflector30Ca deflects the light incident thereon causing the light to spread in a direction parallel to the xy plane, and causing two light beams to exit from the emission surface71. Some light beams output from the emission surface due to the optical deflector30Ca connect a point in the plane500on a line551and the optical deflector30Ca. Other light beams output from the emission surface due to the optical deflector30Ca connect a point in the plane500on a line552and the optical deflector30Ca. Any of the optical deflectors in the optical deflector group330Ca may cause the light beams connecting a point in the plane500on the line551to each of the optical deflectors30, and the light beams connecting a point in the plane500on line552to each of the optical deflectors30to exit from the emission surface71similarly to the optical deflector30Ca. The line551and the line552exist for the most part in a plane parallel to the xy plane and form a portion of the three-dimensional image6C. Each of the optical deflectors30belonging to the optical deflector group330Ca thus spreads the light incident thereon that has an intensity distribution corresponding to the line551and the line552; the light is spread in the x axis direction within a plane parallel to the emission surface71and caused to exit from the emission surface71. Hereby, light from the plurality of optical deflectors30belonging to the optical deflector group330Ca arranged along the x axis direction becomes light that radiates from an image of the line551and the line552.

The optical deflector30Cb deflects the light incident thereon causing the light to spread in a direction parallel to the xy plane, and causing three light beams to exit from the emission surface71. The three light beams output from the emission surface71are namely light beams connecting a point in the plane500on a line561and the optical deflector30Cb, light beams connecting a point in the plane500on a line562and the optical deflector30Cb, and light beams connecting a point in the plane500on a line563and the optical deflector30Cb. Any of the optical deflectors in the optical deflector group330Cb may cause the light beams connecting a point in the plane500on the line561to each of the optical deflectors30, the light beams connecting a point in the plane500on the line562to each of the optical deflectors30, and the light beams connecting a point in the plane500on line563to each of the optical deflectors30to exit from the emission surface71similarly to the optical deflector30Cb. The line561, the line562, and the line563exist for the most part in a plane parallel to the xy plane and form a portion of the three-dimensional image6C. Thus, each of the optical deflectors30belonging to the optical deflector group330Cb spreads the light incident thereon that has an intensity distribution corresponding to the line561, the line562, and the line563; the light is spread in the x axis direction within a plane parallel to the emission surface71and caused to exit from the emission surface71. Hereby, light from the plurality of optical deflectors30belonging to the optical deflector group330Cb arranged along the x axis direction becomes light that radiates from an image of the line561, the line562, and the line563.

The optical deflector30Cc deflects the light incident thereon causing the light to spread in a direction parallel to the xy plane, and causing two light beams to exit from the emission surface71. The two light beams output from the emission surface71are namely light beams connecting a point in the plane500on a line571and the optical deflector30Cc and light beams connecting a point in the plane500on a line572and the optical deflector30Cc. Any of the optical deflectors in the optical deflector group330Cc may cause the light beams connecting a point in the plane500on the line571to each of the optical deflectors30, and the light beams connecting a point in the plane500on line572to each of the optical deflectors30to exit from the emission surface71similarly to the optical deflector30Cc. The line571and the line572exist for the most part in a plane parallel to the xy plane and form a portion of the three-dimensional image6C. Each of the optical deflectors30belonging to the optical deflector group330Cc thus spreads the light incident thereon that has an intensity distribution corresponding to the line571and the line572; the light is spread in the x axis direction within a plane parallel to the emission surface71and caused to exit from the emission surface71. Hereby, light from the plurality of optical deflectors30belonging to the optical deflector group330Cc arranged along the x axis direction becomes light that radiates from an image of the line571and the line572.

Thus, the display device10C gathers light beams from the two-dimensionally arranged plurality of optical deflectors to present light beams that radiate from the image6B in the space near an observer. The location at which the three-dimensional image6C is formed is opposite the emission surface71in the display device10C; the plane500in which the three-dimensional image6C is formed does not intersect with the light beams output from the emission surface71. However, similarly to the display device10C, light beams output from the emission surface by way of the optical deflectors30also connect a point on a line forming the three-dimensional image and the optical deflector30in the display device10B. Therefore, the identical configurations pertaining to the display device10B may be adopted in the display device10C. Thus, further detailed description of the display device10C is omitted.

The above describes examples of producing a three-dimensional image in a plane orthogonal to the emission surface with reference toFIG. 20throughFIG. 27. However, the location of the three-dimensional image is not limited to a within a plane perpendicular to the emission surface71. The location of the three-dimensional image is not limited as long as the same is not within a plane parallel to the emission surface71.

Again, the optical deflectors30may be provided as a matrix in the xy plane as above described. For instance, the optical deflectors30may be provided at equal pitch in the x axis direction and at equal pitch in the y axis direction. Here the pitch of the optical deflectors30in the x axis direction may be the same or different from the pitch in the y axis direction. The pitch of the optical deflectors30may be smaller in the x axis direction than in the y axis direction. The density of the points in the x axis direction in the three-dimensional image6increases when the pitch of the optical deflectors30is smaller in the x axis direction than in the y axis direction. Therefore, the points forming the three-dimensional image6are connected along the x-axis direction allowing those points to be more easily perceived as a line. Hereby, an observer can easily recognize both ends of the line and more easily perceive the form of the three-dimensional image6.

The pitch of the optical deflectors30may be varied within the xy plane. Varying the pitch of the optical deflectors30in the xy plane makes it possible to modify the resolution of the three-dimensional image6in each region. Additionally, the optical deflectors30need not be provided regularly. The optical deflectors30may be provided randomly within the xy plane.

FIG. 28Ais a plan view along the xy plane of the display device10D to illustrate an example of modifying the display device10B. The display device10D differs from the display device10B in that the display device10D is equipped with a light-incidence tuning portion50D that includes a plurality of integrally molded lenses51D on the first edge73. The lenses51D are convex portions protruding from the first edge73toward the negative y axis direction in the xy plane.

The lenses51BA are cylindrical planoconvex lenses and may be used instead of the lenses51B in the display device10DB. The lenses51BA protrude toward the negative y axis direction in the xy plane. The lenses51B may be replaced by cylindrical planoconvex lenses which protrude toward the negative y axis direction in the xy plane.

Above, a linear prism or an arc-shaped prism, as well as an optical surface forming a Fresnel lens are provided as examples of optical surfaces functioning as the optical deflectors30. A diffraction surface such as a diffraction grating may be adopted as the optical surface functioning as the optical deflectors30. Any of these optical surfaces may be inclined relative to the emission surface71. The diffraction surface may be provided on the rear surface72or on the emission surface71when the same is adopted as the optical deflector30. Beyond reflection and diffraction, an optical surface may be used that deflects light by refracting the light from the light source.FIG. 29Ais a cross-sectional view along the yz plane of a display device E provided with a refraction surface43to illustrate an example of modifying a part of the optical deflector30.FIG. 29Aschematically illustrates the yz plane of a display device10F provided with a refraction surface44to illustrate an example of modifying a part of the optical deflector30. As illustrated inFIG. 29AandFIG. 29B, the refraction surface43is provided on the emission surface71.

The display device10and the modifications thereof described above are configured such that each of the optical deflectors provided two dimensionally in a plane parallel to the emission surface of the light guide plate70supply light forming images at a plurality of locations in the three-dimensional image. Therefore, the three-dimensional image may be viewed from a wide range. At least a portion of the three-dimensional image may also be formed as a plane and not necessarily as a point.

The present invention is hereby described by way of embodiments; however, the technical scope of the present invention is not limited to the above-described embodiments. It is obvious to a person skilled in the art that the above described embodiments can be modified or improved in various ways. The scope of the claims makes it clear whether such kind of modifications or improvements to the embodiments is within the technical scope of the present invention.

It should be noted that unless explicitly stated with terms such as “before”, “prior to”, and the like, and unless the output of a prior process is used in a subsequent process, the sequence of execution of operations procedures, steps, and stages within the devices, systems, programs, and methods expressed in the scope of the claims, the specification, and the drawings, may be executed any order as desired. The terms “first”, “next”, and the like are used for convenience when describing operational flows within the scope of the claims, the specification, and in the drawings, and does not mean that execution in this order is required.