Optical device for stereoscopic imaging with a light guide plate

Abstract

Optical device (1A), comprising: a light guide plate (10) configured to guide light entering it from a light source (2), to change the path of the guided light and to cause this light to emerge from an emission surface (12) of the light guide plate (10) and thus form an image in a space; a group of narrow-field beam deflectors (27) configured to produce an image in a room in a narrow viewing direction, which is assumed to be an angle greater than 0° and less than a first angle with respect to a reference plane that is perpendicular to the emitting surface (12) and parallel to a side surface of the light guide plate; and a group of wide-field beam deflectors (28) configured to produce an image in a room in a wide viewing direction, which is assumed to be an angle greater than the first angle and less than 90° with respect to the reference plane; wherein the group of beam path deflectors with narrow field of view (27) and the group of beam path deflectors with wide field of view (28) exhibit different image formation conditions, wherein the group of beam path deflectors with narrow field of view (27) forms a stereoscopic image in a space different from the light guide plate (10), while the group of beam path deflectors with wide field of view (28) forms a two-dimensional image on the emission surface of the light guide plate (10), and wherein the group of beam path deflectors with wide field of view (28) is arranged on a surface of the light guide plate (10) whose surface is opposite the emission surface (12).

Description

AREA OF INVENTION

[0001] The present invention relates to an optical device for stereoscopic representation with a light guide plate, which is configured to display a stereoscopic image. STATE OF THE ART

[0002] The image display device disclosed in the Japanese patent publication with publication number JP 2012 - 118 378 A (published on June 21, 2012) provides an example of a known optical device configured to display a stereoscopic image.

[0003] Japanese patent publication number JP 2012-118378A discloses an image display device 100 equipped with a light guide plate 110 and a light source 101 provided at one end of the light guide plate 110. Display patterns for the left eye 111a, 112a, 113a with multiple first prisms and display patterns for the right eye 111ba, 112ba, 113ba with multiple second prisms are provided on the rear surface of the light guide plate 110. Fig. 28A). The above display pattern for the left eye 111a uses several prisms P1 to create a symbol “A” in a two-dimensional plane, and the display pattern for the right eye 111b uses several prisms P2 to create a symbol “A” in a two-dimensional plane ( Fig. 28B).

[0004] In this configuration, the multiple first and second prisms reflect light from the light source 101 to project an image for the left eye and an image for the right eye onto the front surface of the light guide plate 110. When a viewer looks at the image for the left eye and the image for the right eye, the viewer perceives each of the viewed images 120 of "A", "B", and "C" as planar images that appear three-dimensional and as in Fig. 28C shows the images arranged from furthest to the nearest in this order. The viewed images 120 are perceived as floating at the intersection of the light rays from the images for the left eye and the images for the right eye; thus, the viewed images with larger intervals have intersection points that are closer to the viewer and therefore appear to be even closer. Thus, the viewer can perceive a natural three-dimensional representation. Further prior art is provided by JP 5 701 434 B1. JP 5 701 434 B1 discloses a display panel made of a transparent material, comprising a point-shaped reflective element on the surface or within the display panel as a component and a group of elements that together display a specific pattern, the group of elements being provided for each of a plurality of preset viewing angles. Technical task

[0005] As an example, a stereoscopic image is used that emerges laterally from a wall three meters (3 m) ahead in a corridor, when viewed by a viewer who is one meter (1 m) away from a wall ( Fig. 29A). In order for the viewer to recognize this as a stereoscopic image, the viewer must view the image from an angle of at least 75° to the normal vector of the wall ( Fig. 29B).

[0006] However, an existing image display device 100 is disadvantaged because the stereoscopic image it produces appears distorted in the room; furthermore, the stereoscopic image hardly appears three-dimensional in a wide viewing angle greater than 60° with respect to the normal vector of the wall.

[0007] This is due to two reasons.

[0008] First, light in the optical fiber plate with an emission angle γ is considered in relation to the normal vector of the emission surface ( Fig. 30A); at an emission angle γ = 30°, the propagation sensitivity is nearly 1 and the shape of the stereoscopic image is less susceptible to propagation. However, at an emission angle γ = 75°, the propagation sensitivity is nearly 19 and the shape of the stereoscopic image is more susceptible to propagation. The propagation sensitivity of the shape of the stereoscopic image increases sharply when the emission angle γ = 60°. This is because errors in the shape strongly affect blurring in the sections within a wide viewing angle when the emission angle γ is greater than or equal to 75°. Here, the term "propagation sensitivity" refers to the ratio between the magnitude of change in the emission angle of light emitted at 0° to the normal vector of the emission surface with a small change to the angle in which light enters the optical fiber plate (i.e.,The propagation sensitivity is determined by the direction of light (the optical fiber angle) and the change in the emission angle of light emitted in multiple directions with a small change relative to the optical fiber angle. The propagation sensitivity is 1 when the emission angle is 0°.

[0009] Secondly, blurring is less likely when generating the stereoscopic image, since a narrow area is visible at a viewing angle of 0°, whereas blurring tends to be more obvious because a larger proportion of the light emitted from a wide area is seen from sections at the wide viewing angle of 60° ( Fig. 31).

[0010] In view of the problem described above, the invention is based on the objective of providing an optical device that is able to prevent the visibility of a stereoscopic image in a room from being deteriorated in a wide viewing direction. SUMMARY

[0011] This problem is solved by the subject matter of the independent claims. Preferred embodiments of the invention are the subject matter of the dependent claims. The invention is defined by the claims, aspects of which are explained below: According to one aspect of the invention, an optical device for stereoscopic representation is configured such that the optical device comprises: a light guide plate configured to guide light entering it from a light source, to change the path of the guided light, and to cause this light to emerge from an emissive surface of the light guide plate, thus forming an image in space;A group of narrow-field beam deflectors configured to produce an image in a space in a narrow viewing direction, which is assumed to be an angle greater than 0° and less than a first angle with respect to a reference plane perpendicular to the emitting surface and parallel to a side surface of the optical fiber plate; and a group of wide-field beam deflectors configured to produce an image in a space in a wide viewing direction, which is assumed to be an angle greater than the first angle and less than 90° with respect to the reference plane; and wherein the narrow-field beam deflectors group and the wide-field beam deflectors group have different image formation conditions. Effects

[0012] Aspects of the invention provide an optical device which has the effect of preventing the visibility of a stereoscopic image in a room from being deteriorated in a wide viewing direction. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1A is a perspective view of a first embodiment of an optical device according to the invention and represents a configuration of an optical device that produces a stereoscopic image and a two-dimensional image in space; and Fig. 1B is a cross-sectional view of the xz-plane, representing a configuration of the optical device that produces the stereoscopic image and the two-dimensional image in a space; Fig. Figure 2 is a cross-sectional view of a configuration of the optical device; Fig. Figure 3 is a perspective view of the configuration in the optical device for forming a planar image; Fig. Figure 4 is a perspective view of the configuration in the optical device for forming a planar image; Fig. Figure 5 is a front view showing an example of a stereoscopic image consisting of a planar image formed by the optical device; Fig. Figure 6 is a perspective view of an example of configuring prisms in a light guide plate in the optical device for forming the planar image; Fig. 7A is a perspective view showing an example of the arrangement of the prisms in the light guide plate in the optical device; Fig. 7B, Fig. 7C and Fig. 7D are perspective views of modifications to prism configurations; Fig. 8A, Fig. 8B and Fig. Figure 8C are top views that schematically illustrate examples of how to arrange prisms in the light guide plate in the optical device to form the planar image; Fig. Figure 9 is another example of modifying the prisms in the light guide plate in the optical device for forming the planar image, and it is a perspective view of the shapes of the prisms when the prisms form planar images as parallax images; Fig. Figure 10 is a perspective view showing a configuration of a group of second beam path deflectors in the optical device, which form line images; Fig. Figure 11A is a top view showing a configuration of a group of second beam deflectors in the optical device forming a line image; and Figure 11B is a top view showing an example of modifying the configuration of the group of second beam deflectors in the optical device forming a line image; Fig. Figure 12A is a perspective view showing a configuration of a group of second beam deflectors in the optical device forming a point image; and Figure 12B is a perspective view showing the configuration of the group of second beam deflectors forming a point image and a two-dimensional image; Fig. Figure 13A represents an example of the shape for a group of wide-field beam deflectors in the optical device that form the two-dimensional image; Fig. 13A is a top view showing the two-dimensional image that forms an arrow consisting of several points; Fig. 13B is a top view showing the prisms in the group of wide-field beam deflectors arranged in a section to form a single point; Fig. 13C and Fig. Figure 13D represents examples of prism shapes in the group of wide-field beam deflectors; Fig. 14A, Fig. 14B and Fig. 14C are perspective views that provide another example of modifying the shape of a prism in a group of wide-field beam deflectors in the optical device; Fig. Figure 15 is a graph showing the relationship between the viewing angle and the location where an image is formed in the optical device; Fig. Figure 16A is a cross-sectional view showing a group of narrow-field beam deflectors and a group of wide-field beam deflectors forming a stereoscopic image and a two-dimensional image in space, respectively; and Fig. Figure 16B is a cross-sectional view showing the arrangement of the group of wide-field beam deflectors when the position of the two-dimensional image is changed; Fig. 17 is a top view of a first angle of the optical device; Fig. 18A is a top view showing a configuration of the optical device according to the first embodiment in which the group of narrow field-of-view beam deflectors and the group of wide field-of-view beam deflectors are arranged at the same intervals; Fig. Figure 18B represents a second embodiment of an optical device according to the present invention and is a top view of a configuration of the optical device, wherein the group of wide-field beam deflectors is arranged at larger intervals than the group of narrow-field beam deflectors; Fig. Figure 19 is a graph showing the relationship between the viewing angle of the optical device and the step size of the groups of wide-field and narrow-field beam deflectors; Fig. 20A is a top view showing viewpoints fixed at uniform intervals along a horizontal direction; Fig. 20B is a perspective view generated from parallax images arranged with a uniform step size, provided the viewing points have a uniform step size along the horizontal direction; and Fig. 20C is a cross-sectional view of the xz-plane, representing a stereoscopic image generated from parallax images with a uniform step size. Fig. 21A provides an optical device according to a third embodiment of the invention and is a top view showing the arrangement of the group of beam path deflectors with a wide field of view at a constant angular step size when the stereoscopic image is generated from parallax images; Fig. Figure 21B is a perspective view showing where the interval between adjacent parallax images increases with increasing viewing angle; and Fig. 21C is a cross-sectional view of the xz-plane showing a stereoscopic image generated from parallax images arranged at different step sizes; Fig. Figure 22 is an example of modifying the optical device according to the third embodiment and is a perspective view showing the optical device forming a two-dimensional image in an area outside a specified wide viewing angle when the optical device uses parallax images to form the stereoscopic image; Fig. 23A and Fig. Figures 23B are top views of a fourth embodiment according to the invention and they represent a configuration of the optical device wherein the light source is arranged at a corner of the light guide plate; Fig. 24A is a top view showing the stereoscopic image as viewed from a narrow viewing angle; Fig. 24B is a perspective view showing how the stereoscopic image appears when viewed from the narrow viewing direction; Fig. 25A is a top view showing the view when the stereoscopic image is viewed from a wide viewing angle; Fig. 25B is a perspective view showing how the stereoscopic image appears when viewed from the wide viewing direction; Fig. Figure 26A is a top view of a fifth embodiment according to the invention and shows the stereoscopic image when viewed from a narrow viewing direction; Fig. 26B is a perspective view showing how the stereoscopic image appears when viewed from the narrow viewing direction; Fig. Figure 27A is a top view of a fifth embodiment according to the invention and shows the stereoscopic image as viewed from a wide viewing direction; Fig. Figure 27B is a perspective view showing how the stereoscopic image appears when viewed from the wide viewing direction; Fig. 28A to 28C inclusive represent configurations of an image display device that serves as a conventional optical device; Fig. 29A is a perspective view that presents a stereoscopic image formed as it emerges laterally from a wall in a corridor; Fig. Figure 29B is a top view showing the relationship between the stereoscopic image and a viewer looking at the stereoscopic image; Fig. 30A and Fig. Section 30B serves to explain the first reason why the visibility of the stereoscopic image deteriorates at a wide viewing angle; and Fig. Section 31 serves to explain the second reason why the visibility of the stereoscopic image deteriorates at a wide viewing angle. DETAILED DESCRIPTION First embodiment

[0013] In the following, an embodiment of the invention is described with reference to Fig. 1A up to and including Fig. 17 described. Configuration of the optical device

[0014] The configuration of an optical device 1A according to the embodiment is based on Fig. 1A, Fig. 1B, Fig. 1C and Fig. 2 described. Fig. Figure 1A is a perspective view of an optical device 1A according to the invention and represents a configuration of the optical device 1A that produces a stereoscopic image I and a two-dimensional image 2D in a space; Fig. 1B is a cross-sectional view of the xz-plane, representing a configuration of the optical device 1A, which produces the stereoscopic image I and the two-dimensional image 2D in a space; Fig. Figure 2 is a cross-sectional view showing a configuration of the optical device 1A.

[0015] As in Fig. As shown in Figure 2, the optical device 1A of the embodiment comprises a light source 2, a light guide plate 10, and several beam path deflectors 20 arranged in the light guide plate 10. The light guide plate 10 emits light entering it from the light source 2 via the emission surface 12, and the several beam path deflectors 20 change the beam path of the light directed thereon, causing the light to exit the light guide plate 10 and form a stereoscopic image I in a room.

[0016] The multiple beam path deflectors 20 in this embodiment include a group of beam path deflectors with a narrow field of view 27 and a group of beam path deflectors with a wide field of view 28 ( Fig. 1A and Fig. 1B). The group of beam deflectors with a narrow field of view 27 causes the stereoscopic image I to be formed in a room in a narrow viewing direction extending from 0° or above to below a first angle with respect to a reference plane. The group of beam deflectors with a wide field of view 28 causes an image to be formed in a room in a wide viewing direction that is greater than the first angle and less than 90° with respect to the reference plane. It is noted that the reference plane is perpendicular to the emission surface 12 of the optical fiber plate 10 and parallel to a lateral surface 14.

[0017] The light source 2 can, for example, consist of several light-emitting diodes (LED 2a), as shown in Fig. 2 shown; wherein the light emitted from each of the multiple light-emitting diodes (LED 2a) is modified by a light incidence adjustment section 3 and enters the incidence surface 11 of the light guide plate 10. Although in this embodiment the light source 2 can consist of multiple light-emitting diodes (LED 2a), the light source 2 is not limited to this and can also consist of only a single light-emitting diode (LED 2a).

[0018] The light incidence tuning section 3 is equipped with several lenses 3a, each corresponding to a light-emitting diode (LED) 2a. Each lens 3a can decrease, increase, or modify the propagation of light emitted from the respective LED 2a along its optical axis in the xy-plane. As a result, a lens 3a can cause light emitted from the LED 2a to approximate parallel light, or it can direct the light to all areas within the light guide plate 10. The propagation angle of light directed through the light guide plate 10 is not greater than 5° and is preferably less than 1°. Other configurations can be used to decrease the propagation angle of light in the xy-plane within the light guide plate 10; for example, the light incidence tuning section 3 can have a mask with a window having a width of less than a predetermined value in the x-axis direction.

[0019] In this embodiment, the optical axis of the light emitted from the light-emitting diodes (LED 2a) has an angle θ with respect to the emission surface 12 (described below). For example, the angle θ, which is an acute angle between the optical axis of the light emitted from the LED (LED 2a) and the emission surface 12, is approximately 20°. Therefore, even if the light entering the light guide plate 10 is nearly parallel, it is possible to increase the amount of light that is repeatedly reflected between the emission surface 12 and the rear surface 13 (described below) and directed through the light guide plate 10, compared to the situation where the optical axis of the incident light is parallel to the y-axis.Thus, it is possible to increase the luminous intensity of light entering the beam path deflectors 20 described below compared to the case in which the optical axis of the incident light is parallel to the y-axis.

[0020] The light guide plate 10 is a transparent resin material with a comparatively high refractive index. The light guide plate 10 can be made, for example, from a polycarbonate resin (PC), a polymethyl methacrylate resin (PMMA), glass, or a similar material.

[0021] The light guide plate 10 contains: an incidence surface 11 onto which light from the light source 2 is incident; an emission surface 12, which is the front surface of the light guide plate 10 and emits light; and a rear surface 13 on which the beam path deflectors 20 are formed.

[0022] In this embodiment, light is emitted from the emission surface 12 of the optical fiber plate 10, and this emission of light forms a stereoscopic image I in space. An observer perceives the stereoscopic image I as three-dimensional. It should be noted that the stereoscopic image I can also be perceived as being located at a point other than the emission surface 12 of the optical fiber plate 10. The stereoscopic image I can also be perceived as a two-dimensional image at a location distant from the emission surface 12 of the optical fiber plate 10. In other words, the stereoscopic image I can not only be perceived as having a fixed shape, but it can also exhibit a concept of images with two-dimensional shapes that are perceived at a location other than the optical device 1A.The stereoscopic image I in this embodiment is perceived as being arranged further along the negative z-axis than the emission surface 12. However, there are cases in which the stereoscopic image I can also be perceived as being arranged further along the negative z-axis than the emission surface 12.

[0023] It should be noted that a rectangular coordinate system consisting of the x-axis, y-axis, and z-axis is sometimes used when describing this embodiment. In this embodiment, the z-axis direction is defined as a direction perpendicular to the emitting surface 12, with the positive z-axis extending from the rear surface 13 towards the emitting surface 12. The y-axis direction is defined as perpendicular to the incident surface 11, with the positive y-axis direction extending from the incident surface 11 towards a planar image FI directed towards the incident surface 11. Furthermore, the x-axis extends along a lateral surface of the optical fiber plate 10 in a direction perpendicular to the incident surface 11, with the positive x-axis direction extending in Fig. 1 runs from the left lateral surface to the right lateral surface. To avoid redundancy in the description, planes parallel to the xy, yz, and xz planes are sometimes referred to as the xy plane, the yz plane, and the xz plane, respectively.

[0024] The optical device 1A in this embodiment includes several beam deflectors 20 on the rear surface 13 of the light guide plate 10. The beam deflectors 20 alter the beam path of light directed onto the light guide plate 10, causing the light to exit from there and form a stereoscopic image I in space. The beam deflectors 20 are arranged at different positions in the xy-plane, e.g., in a matrix. For example, the beam deflectors 20 can be prisms.

[0025] This means that, as described above, the light emitted from light source 2 appears as in Fig. 2 shows the light incident via the light-adjusting section 3 onto the incident surface 11 of the light guide plate 10. The light entering the light guide plate 10 is completely reflected between the emitting surface 12 and the rear surface 13 of the light guide plate 10 and is directed towards the more distant end of the light guide plate 10. The beam deflectors 20 change the beam path of light that does not meet the conditions for complete reflection towards a specific orientation and cause light to exit the emitting surface 12.

[0026] The group of beam deflectors with narrow field of view 27 and the group of beam deflectors with wide field of view 28 in the optical device 1A form a stereoscopic image I; this stereoscopic image I can be generated from a line image or it can be a planar image that forms a predetermined shape in space.

[0027] The configuration and function of a group of first beam deflectors, comprising the group of beam deflectors with a narrow field of view 27 and the group of beam deflectors with a wide field of view 28, are described below. This group of first beam deflectors acts as a planar image-forming unit, producing a planar image. The configuration and function of a group of second beam deflectors, which produce a line image, are also described. Forming a planar image

[0028] First, the configuration of the optical device 1A in this embodiment for forming a planar image FI is described below based on: Fig. 3 to Fig. 5 described. Fig. Figure 3 is a perspective view of the configuration in the optical device for forming a planar image FI; Fig. Figure 4 is a perspective view of the configuration in the optical device 1A for forming the planar image; Fig. Figure 5 is a front view showing an example of a stereoscopic image I consisting of the planar image FI formed by the optical device 1A.

[0029] For example, assume that the optical device 1A generates a stereoscopic image I in a plane to form a stereoscopic image parallel to the xz-plane, as in Fig. 3 shown; and more precisely, that the optical device 1A forms a planar image FI as a circle with a diagonal line through it.

[0030] Preferably, the optical device 1A ensures that the light transmitted through the light guide plate 10 propagates largely in the yz-plane. Accordingly, the light incidence adjustment section 3 does not reduce the propagation angle of light from the light source 2 in the xy-plane. This means that the light incidence adjustment section 3 has a largely unaffected effect on the propagation angle of light from the light source 2 in the yz-plane.

[0031] For example, lens 3a in the light incidence adjustment section 3 can be a convex cylindrical lens that is curved in the xy-plane and has essentially no curvature in the yz-plane. Both surfaces of the cylindrical lens can be convex.

[0032] Several groups of first beam deflectors 21a, 21b, 21c,... are formed on the rear surface 13 of the light guide plate 10 in the optical device 1A; the groups of first beam deflectors 21a, 21b, 21c,... serve as the group of beam deflectors 21 of the planar image. Each group of first beam deflectors 21a, 21b, 21c,... is formed from several prisms arranged along a direction parallel to the x-axis. Thus, for example, the group of first beam deflectors 21a consists of several prisms P21a. Similarly, the group of first beam deflectors 21b consists of several prisms 21b, and the group of first beam deflectors 21c consists of several prisms P21c.

[0033] For example, prisms P21a change the path of incident light, spreading it in a direction parallel to the xy-plane and causing it to emerge from the emission surface 12. The light rays emitted from the emission surface 12 by prisms P21a largely form a line that intersects the plane 30 forming the stereoscopic image. As in Fig. 3 and Fig. As shown in Figure 4, the prisms P21a cause the light rays to emerge from the emission surface 12. The two emitted light rays intersect the plane 30 forming the stereoscopic image at line 31a1 and at line 31a2. As shown in Fig. As shown in Figure 3, all prisms P21a contained in the group of first beam deflectors 21a, and other prisms P21a therein, cause light rays to emerge from the emission surface 12 in a similar manner and intersect the plane 30 forming the stereoscopic image at lines 31a1 and 31a2. Lines 31a1 and 31a2 lie essentially in a plane parallel to the xy-plane and form a section of the stereoscopic image I. Thus, light from the several prisms P21a belonging to the group of first beam deflectors 21a forms lines 31a1 and 31a2 in the line image LI. The light that forms images of line 31a1 and line 31a2 can be provided from at least two prisms P21a, wherein P21a are arranged at different locations along the x-axis direction in the group of first beam deflectors 21a.

[0034] This means that several prisms P21a, belonging to the group of first beam deflectors 21a, cause incident light to propagate along the x-axis in a plane parallel to the emitting surface 12; the several prisms P21a cause light with an intensity distribution corresponding to the images of line 31a1 and line 31a2 to emerge from the emitting surface 12. Here, the light from the several prisms P21a, which belong to the group of first beam deflectors 21a and are arranged along the x-axis, is the light that forms the images of line 31a1 and line 31a2.

[0035] As in Fig. As shown in Figure 3, the prisms P21b in the group of first beam deflectors 21b similarly alter the beam path of incident light, spreading the light in a direction parallel to the xy-plane and causing three light rays to emerge from the emitting surface 12. The three light rays emitted from the emitting surface 12 intersect the plane 30 forming the stereoscopic image at lines 31b1, 31b2, and 31b3. All of the prisms P21b contained in the group of first beam deflectors 21b, and other prisms P21b within it, similarly cause light rays to emerge from the emitting surface 12 and intersect the plane 30 forming the stereoscopic image at lines 31b1, 31b2, and 31b3.This means that several prisms P21b, belonging to the group of first beam deflectors 21b, cause incident light to propagate in a plane parallel to the emitting surface 12; the several prisms P21b cause light with an intensity distribution corresponding to the images of lines 31b1, 31b2, and 31b3 to emerge from the emitting surface 12. Here, the light from the several prisms P21b, which belong to the group of first beam deflectors 21b and are arranged along the x-axis, is the light that forms the image of lines 31b1, 31b2, and 31b3. Lines 31b1, 31b2, and 31b3 lie essentially in a plane parallel to the xy-plane and form a section of the stereoscopic image I.

[0036] Here, lines 31b1, 31b2, 31b3 and lines 31a1, 31a2 are formed at different points along the z-axis direction in the plane 30 forming the stereoscopic image.

[0037] As in Fig. As shown in Figure 3, the prisms P21c in the group of first beam deflectors 21c similarly alter the beam path of incident light, spreading the light in a direction parallel to the xy-plane and causing two light rays to emerge from the emitting surface 12. The two light rays emitted from the emitting surface 12 intersect the plane 30 forming the stereoscopic image at lines 31c1 and 31c2. All prisms P21c contained in the group of first beam deflectors 21c, and other prisms P21c within it, similarly cause light rays to emerge from the emitting surface 12 and intersect the plane 30 forming the stereoscopic image at lines 31c1 and 31c2.Accordingly, several prisms P21c, belonging to the group of first beam deflectors 21c, cause incident light to propagate in a plane parallel to the emitting surface 12; the several prisms P21c cause the light to emerge from the emitting surface 12 with an intensity distribution corresponding to the images of lines 31c1 and 31c2. Here, the light from the several prisms P21c, which belong to the group of first beam deflectors 21c and are arranged along the x-axis, is the light that forms the image of lines 31c1 and 31c2. Lines 31c1 and 31c2 lie essentially in a plane parallel to the xy-plane and form a section of the stereoscopic image I.

[0038] Here, lines 31c1 and 31c2, lines 31b1, 31b2 and 31b3 and lines 31a1 and 31a2 are formed at different points along the z-axis direction in the plane 30 forming the stereoscopic image.

[0039] Lines 31c1 and 31c2, lines 31b1, 31b2 and 31b3, and lines 31a1 and 31a2 are formed at different locations along the z-axis direction in the plane 30 that forms the stereoscopic image and are each described separately in Fig. 3 as previously described. However, in reality, the groups of first beam deflectors 21a, 21b, 21c can consist of more groups of first beam deflectors 21a, 21b, 21c,... with a smaller distance between the groups of first beam deflectors 21a, 21b, 21c,... in the y-axis direction. Alternatively, the beam deflection angle for each of the prisms P21a, P21b, P21c can be selected such that even if the groups of first beam deflectors 21a, 21b, 21c,... are separated along the y-axis direction, the lines 31a1, 21a2, the lines 31b1, 31b2, 31b3 and the lines 31c1, 31c2 are formed at locations that are closer together along the z-axis direction. Accordingly, a planar image FI of a circle with a diagonal line as in Fig. 5 is represented as a stereoscopic image I can be perceived.

[0040] Accordingly, the optical device 1A groups light rays from any plurality of prisms P21a, P21b, P21c in the group of first beam deflectors 21a, 21b, 21c,..., which are arranged two-dimensionally; the optical device 1A uses the light rays to form a planar image FI, which is displayed in a space near an observer. Thus, an observer is able to perceive a stereoscopic image I, which consists of a planar image FI over a wide range of positions along the y-axis.

[0041] Shape of the first beam deflectors for forming the planar image. The shape of the prisms P21a, P21b, P21c in the groups of first beam deflectors 21a, 21b, 21c,... for forming the planar image FI is based on Fig. 6 to and including Fig. 8 described. Fig. Figure 6 is a perspective view of an example of configuring prisms P21a in the light guide plate 10 in the optical device 1A to form the planar image; Fig. Figure 7A is a perspective view showing an example of the arrangement of the prisms P21a in the light guide plate 10 in the optical device 1A; Fig. 7B, Fig. 7C and Fig. 7D are perspective views of modifications to the configurations of prisms P21a; and Fig. 8A, Fig. 8B and Fig. Figure 8C are top views showing examples of prisms P21a-P21d in the light guide plate 10 in the optical device 1A for forming the planar image.

[0042] As in Fig. As shown in Figure 6, the prisms P21a in the group of first beam path deflectors 21a can have a frustoconical cross-section and, for example, contain reflection surfaces f1, f2, f3, f4, f5. The reflection surfaces f1, f2, f3, f4, f5 are an example of optical surfaces that act as deflection surfaces and modify the beam path of light; the reflection surfaces f1, f2, f3, f4, f5 are curves oriented in different directions. As described above, in this embodiment, the optical axis of the light-emitting diodes (LEDs 2a) is inclined in the yz-plane by at most an angle θ to the emission surface 12 of the light guide plate 10.Therefore, even if the light entering the light guide plate 10 is nearly parallel, it is possible to increase the amount of light that is repeatedly reflected between the emitting surface 12 and the rear surface 13 and directed through the light guide plate 10 compared to the situation where the optical axis of the incident light is parallel to the y-axis. Thus, it is possible to increase the amount of light incident on the reflecting surfaces f1, f2, f3, f4, f5 compared to the optical axis of the incident light if the optical axis of the incident light is parallel to the y-axis.

[0043] The reflective surface f1 above is a curved, upwardly sloping, inclined surface, curved in a direction parallel to the light L1 guided by the optical fiber plate 10; the light L1 incident on the reflective surface f1 emerges from the emission surface 12 at a different emission angle depending on the point at which the light L1 is incident on the reflective surface f1. As a result, the reflective surface f1 increases the range of light L1 incident on it, for example along a region 31 of the stereoscopic image I, as shown in Fig. Figure 2 shows that in this embodiment, region 31 is parallel to the y-axis. The light reflected from the reflective surface f1 is oriented from the reflective surface f1 in the direction in which region 31 is located, and essentially no light reflected from the reflective surface f1 is radiated to where region 31 is not located. Thus, the light reflected from the reflective surface f1 is essentially only propagated by the reflective surface f1 at an angle in the yz-plane towards region 31. Therefore, the reflective surface f1 modulates the intensity of incident light in the yz-plane at an angular direction and emits the light. Because the reflective surface f1 is curved, it can provide the light that draws the lines in the image, even if the light L1 incident on the reflective surface f1 is parallel light.

[0044] As in Fig. As shown in Figure 6, the reflecting surfaces f2, f3 in the prisms P21a are torus-shaped, with a frustoconical cross-sectional area; the reflecting surfaces f2, f3 surround the reflecting surface f1 and extend along its arc. All of the reflecting surfaces f2, f3 are inclined surfaces, which, like the reflecting surface f1, are inclined upwards to a point. As a result, the light L1 incident on the reflecting surfaces f2, f3 is reflected from them, and the reflecting surfaces f2, f3 broaden the circumference of the light reflected along line 31a1 and line 31a2 in the stereoscopic image I, as shown in Figure 6. Fig. Figure 3. Furthermore, the reflection surface f1 ensures that no lines exist between line 31a1 and line 31a2 in the stereoscopic image I, as shown in Fig. 3 shown.

[0045] As in Fig. As shown in Figure 6, the reflection surfaces f4 and f5 are formed from rising inclined surfaces, which are defined by a diffraction line a portion of the distance along the reflection surfaces f4 and f5. The presence of the reflection surfaces f4 and f5 allows the lines 31c1 and 31c2 to be generated in the stereoscopic image I, as shown in Figure 6. Fig. 3 shown.

[0046] Accordingly, the prisms P21a can, for example, generate the lines 31, i.e., the lines 31a1, 31a2, 31b1, 31b2, 31b3, 31c1, 31c2, which are the basis for generating the planar image FI in the stereoscopic image I, through the shape of the reflection surfaces f1, f2, f3, f4, f5.

[0047] The prisms P21a are in Fig. Figure 6 is represented as a single prism that forms all lines, i.e., lines 31a1, 31a2, 31b1, 31b2, 31b3, 31c1, 31c2, in the planar image FI. However, it appears to be more difficult to use a single prism for all shapes in the actual planar image FI.

[0048] For example, groups of first beam path deflectors 21a, 21b, 21c,... can be provided to form multiple prisms P21a,..., prisms P21b,... and prisms P21c,... as in Fig. 7A is shown.

[0049] The in Fig. The prisms P21a, 21b, and 21c shown in Figure 7A can be horizontally arranged tetrahedral prisms. However, the prisms are not limited to these shapes and can also be curved tetrahedra, curved tetrahedra with an inclined section, or partially corrugated curved tetrahedra, as shown in Figure 7A. Fig. 7B, Fig. 7C, Fig. Illustrated in 7D.

[0050] The several in Fig. The prisms P21a..., P21b..., and 21c... shown in Figure 7A can be distributed in rows along the y-axis direction, as shown in Figure 7A. Fig. 8A is shown. However, the prisms P21a..., prisms 21b..., prisms P21c... and prisms 21d... are not limited to this type of arrangement and can be distributed such that, when viewed along the y-axis, prisms P21a..., prisms 21b..., prisms 21c... and prisms 21d... appear offset by a fixed value along the x-axis ( Fig. 8B). The prisms P21a, prisms 21b, prisms P21c and prisms 21d can also be arcs arranged to appear as a wave ( Fig. 8C). Example of modifying the shapes of the first beam path deflectors to form the planar image.

[0051] To describe the shapes of the groups of first beam deflectors 21a, 21b, 21c,... used to create the planar image FI, the previous section describes the shapes of the prisms P21a, 21b, 21c that form the lines 31a1, 31a2, 31b1, 31b2, 31b3, and 31c1, 31c2, which are the basis of the planar image FI. However, the groups of first beam deflectors 21a, 21b, 21c,... used to create the planar image FI are not limited to these shapes. For example, a prism P22 can be shaped to match the shape of the planar image FI. Providing several of the prisms P22 allows a group of third beam path deflectors 22 to serve as a group of beam path deflectors of the planar image 21, forming the planar image FI.

[0052] The shape of the prisms P22, which describes a case in which the shape of the prisms forms the planar image FI without change, is based on Fig. 9 described. Fig. Figure 9 is a perspective view representing the shape of a prism P22, which forms the planar image FI as a parallax image.

[0053] The prism P22 is a convex reflective surface and it is formed on the rear surface 13 of the light guide plate 10, as shown in Fig. Figure 9 shows the convex reflective surface of the prism P22 is configured to change the path of light directed onto it in the light guide plate 10 and to cause the light to exit the emission surface 12 as light rays passing through the plane 30 forming the stereoscopic image.

[0054] For example, the outer convex surface of prism P22 is provided with a labeling section P22a on which a character “A” is formed, and outside the labeling section P22a is an antireflective film section P22b. Light entering the antireflective film section P22b is not reflected from there.

[0055] In contrast, the light entering the labeling section P22a (e.g., for the letter "A") is reflected from there. Thus, the prism P22 alters the path of the entering light, causing it to exit the emission surface 12 as light rays that pass through a stereoscopic image I of the letter A.

[0056] The antireflective film section P22b can be produced by coating the rear surface 13 of the light guide plate 10 with black ink, except for the marking section P22a (e.g., for the letter "A"). The antireflective film section P22b (e.g., for the letter "A") can also be produced by printing with black ink and omitting the marking section P22a.

[0057] Accordingly, taking into account the fact that the labeling section P22a can be generated by printing the black ink material after forming the convex sections of the rear surface 13 of the light guide plate 10, this simplifies the process of manufacturing the prism P22.

[0058] For example, generating a labeling section P22a on the prism P22 (e.g. for the letter “A”) in this way makes it possible to form a stereoscopic image I from a planar image FI using the parallax imaging method proposed in the Japanese patent publication number JP 2012 - 118 378 A. Forming a line drawing

[0059] The optical device 1A of this embodiment can also form a line image LI in space, which constitutes the stereoscopic image I. In this case, the beam path deflectors 20 consist of groups of second beam path deflectors 25, which form a line image LI.

[0060] A configuration of the groups of second beam path deflectors 25, which form the line pattern LI, is subsequently based on Fig. 10 described. Fig. Figure 10 is a perspective view showing a configuration of groups of second beam deflectors 25 forming a line image LI.

[0061] It is assumed that line images LI of the letter "A" are formed as the stereoscopic image I in a space, as in Fig. 10 shown.

[0062] In this case, light from the light source 2 enters the light guide plate 10, and several groups of outline image beam path deflectors 24 are formed on the rear surface 13 of the light guide plate 10 in the optical device 1A in this embodiment; the group of outline image beam path deflectors 24 consists of groups of second beam path deflectors 25a, 25b, 25c, 25d, 25e, 25f, 25g. It should be noted that the light source 2 can be configured by a single light-emitting diode (LED 2a); furthermore, the light source 2 can be mounted towards the end surface opposite the incidence surface 11 of the light guide plate 10. This means that a light source 2 can be provided at the incidence surface 11 of the light guide plate 10 to form the planar image FI, and another light source 2 can be provided at the end surface opposite the incidence surface 11 to form the line image LI.

[0063] Sections of groups of second beam deflectors 25a-25g for forming the line image LI are formed from a Fresnel lens. The groups of second beam deflectors 25a-25g are largely continuous along the x-axis direction.

[0064] Spacing can be provided between the multiple refractive surfaces (prism surfaces) that act as the Fresnel lens in the groups of secondary beam deflectors 25a-25g. The light guide plate 10 directs light along an x-axis direction to each location of a group of secondary beam deflectors 25a-25g. The groups of secondary beam deflectors 25a-25g cause incident light to converge at essentially a defined point at each location of the groups of secondary beam deflectors 25a-25g. Fig. Figure 10 represents the convergence of several light beams from the group of second beam deflectors 25a-25g.

[0065] More precisely, the group of second beam deflectors 25a corresponds to a point image PI of a fixed point PA in the stereoscopic image I. The light rays from each position in the group of second beam deflectors 25a converge at the fixed point PA in the stereoscopic image I. Therefore, the optical wavefront from the group of second beam deflectors 25a appears as an optical wavefront radiating from the fixed point PA.

[0066] Next, the group of second beam deflectors 25b corresponds to a point image PI of a fixed point PB in the stereoscopic image I. The light rays from each position in the group of second beam deflectors 25b converge at the fixed point PB in the stereoscopic image I. Thus, the light rays from the positions of any group of second beam deflectors 25a-25g converge at a fixed point corresponding to the groups of second beam deflectors 25a-25g. Here, the groups of second beam deflectors 25a-25g can represent an optical wavefront that appears to radiate from a corresponding fixed point.The point images PI of the defined points PA-PG, which correspond to the groups of second beam deflectors 25a-25g, are distinct from one another; furthermore, the grouping of the several defined points PA-PG according to the groups of second beam deflectors 25a-25g forms the stereoscopic image I in a space. In this way, the optical device 1A projects a stereoscopic image I into a space.

[0067] This means that, in this embodiment, the groups of second beam path deflectors 25a-25g are formed close to the y-axis direction in the optical device 1A. As a result, the grouping of the multiple fixed points PA-PG is perceived by the human eye essentially as a line image LI in the stereoscopic image I.

[0068] Here, the light rays guided through the optical fiber plate 10 and passing through the positions in the optical fiber plate 10 in the xy-plane exhibit a propagation angle around the direction connecting each position in the optical fiber plate and the light source 2, which is smaller than a specified value. Furthermore, in a plane perpendicular to the xy-plane, which contains a line connecting each position in the optical fiber plate 10 and the light source 10, the light rays guided through the optical fiber plate 10 and passing through the positions in the optical fiber plate 10 in the xy-plane exhibit a propagation angle around the direction connecting each position in the optical fiber plate and the light source 2, which is smaller than a specified value.The groups of second beam deflectors 25a-25g can be located at a position remote from the light source 2; in this case, the light rays guided by the light guide plate 10 and incident on the groups of second beam deflectors 25a-25g do not generally propagate in the xy-plane around the y-axis direction. Therefore, light from the groups of second beam deflectors 25a essentially converges to a single fixed point in a plane containing the fixed point PA and parallel to the xz-plane.

[0069] When the light incident on the groups of second beam deflectors 25a-25g propagates in the z-direction, light from the groups of second beam deflectors 25a-25g converges along the y-axis on a line in space containing the specified point, as described below. What is discussed here is the propagation of light in the xy-plane from the light incident on the groups of second beam deflectors 25a-25g, and, more importantly, the convergence of light from the groups of second beam deflectors 25a-25g in the xy-plane; thus, these concepts are represented as light from the groups of second beam deflectors 25a-25g converging at a specified point.

[0070] As in Fig. As shown in Figure 10, the group of second beam deflectors 25a is formed along a line. The group of second beam deflectors 25b is also formed along a line. The groups of second beam deflectors 25a and 25b are each formed on a straight line parallel to the x-axis. Each of the groups of second beam deflectors 25a-25g is formed largely continuously along a straight line parallel to the x-axis direction. Thus, the groups of second beam deflectors 25a-25g are each formed with their length perpendicular to the light-guiding direction of the optical fiber plate 10 in a plane parallel to the emission surface 12.

[0071] Thus, the groups of second beam deflectors 25a-25g are arranged along a predetermined line in a plane parallel to the emitting surface 12. Light guided by the light guide plate 10 incidents on each of the groups of second beam deflectors 25a-25g, and the groups of second beam deflectors 25a-25g cause emitted light to be emitted from the emitting surface 12 in a direction that essentially converges at a single point of convergence in space. It is noted that if the predetermined point is located near the rear surface 13 of the light guide plate 13, the emitted light will radiate from the predetermined point.Accordingly, if the specified point is located close to the rear surface 13 of the light guide plate 10, the reflection surfaces in the groups of second beam path deflectors 25a-25g cause the emitted light from the emitting surface 12 to radiate in such a direction that the light largely radiates from a single convergence point in a space. Shape of the second beam path deflectors for forming the line image

[0072] The groups of second beam path deflectors 25a, 25b, 25c, 25d, 25e, 25f, 25g in the optical device 1A of this embodiment serve to form a line image LI; the groups of second beam path deflectors 25a, 25b, 25c, 25d, 25e, 25f, 25g are based on Fig. 11A, Fig. 11B, Fig. 12A and Fig. 12B described. Fig. Figure 11A is a top view showing a configuration of a group of second beam path deflectors 25a in the optical device 1A for forming a line image LI; and Fig. Figure 11B is a top view showing an example of modifying the group of second beam path deflectors 25a in the optical device 1A to form a line image LI. Fig. 12A is a perspective view showing the focusing of light from the group of in Fig. 11A represents the second beam path deflector 25a; and Fig. 12B is a perspective view showing a configuration of groups of second beam deflectors forming point images and a two-dimensional image.

[0073] As in Fig. As shown in Figure 11A, each of the deflectors in the group of secondary beam deflectors 25a can form an image from a portion of a Fresnel lens. This portion of the Fresnel lens can consist of concentric circles cut into strips. The group of secondary beam deflectors 25a configured in this way is such that the radius in the middle is larger than the radius at the ends for each of the deflectors in the group. Accordingly, light entering the middle of the group of secondary beam deflectors 25a converges at the specified point PA directly above the middle ( Fig. 12A); furthermore, light entering at the ends of the group of second beam deflectors 25a is largely refracted in order to then converge at the specified point directly above the center. This means that the group of second beam deflectors 25a in this embodiment is configured such that all prisms cause light to converge at the specified point PA, since prisms with different orientations lie on a straight line. A large proportion of the light converges at the specified point PA because several prisms P25a cause light to converge there. Therefore, the actual line images LI produced by aligning the specified points PA to and including PG naturally consist of a large amount of light.

[0074] Accordingly, the line images LI formed by the group of second beam deflectors 25a in the optical device 1A are clear and consist of a large amount of light. Therefore, the line images LI formed by the group of second beam deflectors 25 in this embodiment are preferably used to overlay the planar image FI formed by the group of first beam deflectors 21.

[0075] All optical beam deflectors in the group of second beam deflectors 25a are described as causing light to converge at the fixed point PA directly above the center, as in Fig. 12A. However, the embodiments are not limited to this. For example, the deflectors at the ends of the group of second beam path deflectors 25a can cause light to converge at a different point, as in Fig. Figure 12B shows that a group of second beam deflectors 25 can form the (below described) two-dimensional image 2D.

[0076] As in Fig. As shown in Figure 11A, the lenses in the group of second beam path deflectors 25a are arranged at a fixed interval. However, the lenses are not limited to this arrangement. For example, as shown in Fig. 11B the lenses in the group of second beam deflectors 25a may be arranged at large intervals.

[0077] This means that a group of second beam path deflectors 25a' can be equipped with several groups of lenses 25a' along the x-axis direction, as in Fig. 11B is shown.

[0078] The group of second beam deflectors 25a contains optical surfaces that vary continuously along the length of the group of second beam deflectors 25a. In contrast, the group of second beam deflectors 25a' contains optical surfaces that vary periodically along the length of the group of second beam deflectors 25a', similar to the multiple groups of lenses P25a'. Thus, light from the group of lenses P25a' converges in the group of second beam deflectors 25a' at the same fixed point PA, which corresponds to the group of second beam deflectors 25a'. The light intensity distribution of the light from the group of lenses P25a' along the x-axis direction essentially has a peak at the position of the fixed point PA and decreases significantly with increasing distance from the fixed point PA.

[0079] In contrast, if the optical surfaces of the group of second beam deflectors 25a are continuous without interruption in the x-axis direction, light from one section of the optical surfaces overlaps with some of the light from optical surfaces surrounding that section. Therefore, light from such sections tends to exhibit a broader intensity distribution compared to the case where the groups of lenses P25a' are spaced close together along the x-axis. This means that the group of second beam deflectors 25a' can be divided into several groups of lenses 25a'. Consequently, the width of the light intensity distribution from each of the groups of lenses P25a' can be reduced compared to the case where they are spaced apart.Accordingly, dividing the group of second beam path deflectors 25a' into several groups of lenses P25a' can lead to the so-called black matrix effect and increase the contrast of the image.

[0080] Instead of cylindrical Fresnel lenses, a refractive grating can be used as the group of second beam deflectors 25a and as the group of second beam deflectors 25a'. A group of second beam deflectors 25a configured from prisms with reflective surfaces can serve as the group of second beam deflectors 25a and as the group of second beam deflectors 25a'. Forming a highly visible image in the room within a wide line of sight

[0081] As previously described, the case is used in which a stereoscopic image emerges laterally from a wall three meters (3 m) ahead in a corridor and is viewed by a viewer who is one meter (1 m) away from the wall ( Fig. 29A). In order for the viewer to recognize that this is a stereoscopic image, the viewer must view the image from an angle of at least 75° to the normal vector of the wall ( Fig. 29B). One reason for this is the following.

[0082] Light in the optical fiber plate is considered with an emission angle γ relative to the normal vector of the emission surface; at an emission angle γ = 30°, the propagation sensitivity is almost 1 and the shape of the stereoscopic image is less susceptible to propagation ( Fig. 30A and Fig. 30B). However, at an emission angle γ = 75°, the propagation sensitivity is nearly 19, and the shape of the stereoscopic image is more susceptible to propagation. The propagation sensitivity of the shape of the stereoscopic image increases sharply when the emission angle γ = 60°. This is because errors in the shape strongly affect blurring in the sections within a wide viewing angle when the emission angle γ is greater than or equal to 75°.

[0083] To address this task, the optical device 1A of this embodiment includes a group of beam path deflectors with a narrow field of view 27 and a group of beam path deflectors with a wide field of view 28 ( Fig. 1A and Fig. 1B). The group of beam deflectors with a narrow field of view 27 causes the stereoscopic image I to be formed in a room in a narrow viewing direction extending from 0° or above to below a first angle α with respect to a reference plane BL. The group of beam deflectors with a wide field of view 28 causes an image to be formed in a room in a wide viewing direction that is greater than the first angle α and less than 90° with respect to the reference plane BL. It is noted that the reference plane BL is perpendicular to the emission surface 12 of the light guide plate 10 and parallel to the side surface 14. The group of beam deflectors with a narrow field of view 27 and the group of beam deflectors with a wide field of view 28 exhibit different image formation conditions.

[0084] More precisely, the group of beam path deflectors with narrow field of view 27 forms a stereoscopic 3D image as a stereoscopic image I in a space different from the light guide plate 10, i.e. above the emission surface 12 ( Fig. 1A and Fig. 1B). In contrast, the group of beam path deflectors with a wide field of view 28 forms a two-dimensional image 2D on the emission surface 12 of the light guide plate 10. The two-dimensional image 2D is formed at a fixed position on the emission surface 12 of the light guide plate 10, regardless of the angle in the wide viewing direction.

[0085] As a result, it is possible to ensure that the stereoscopic image I is not blurred over a wide viewing angle. Accordingly, an optical device 1A can be provided which is capable of preventing the visibility of a stereoscopic image I in a room from deteriorating over a wide viewing direction.

[0086] Furthermore, the two-dimensional image (2D) is formed in a space within a wide viewing direction, thus enabling the representation of an image that is not blurry. This means that a stereoscopic image formed in a space within a wide viewing direction is hardly distinguishable from a two-dimensional image, even if the stereoscopic image is not blurry. Therefore, seeing a sharp two-dimensional image (2D) causes less discomfort than seeing a blurry stereoscopic image (I).

[0087] Accordingly, an optical device 1A can be provided which is able to prevent the visibility of a stereoscopic image I in a room in a wide viewing direction from being deteriorated. Shape of the beam path deflectors with a wide field of view for forming the two-dimensional image.

[0088] Here, the shape of the group of beam path deflectors with a wide field of view 28 in the optical device 1A is based on Fig. 13A, Fig. 13B, Fig. 13C, Fig. 13D and Fig. 14A, Fig. 14B and Fig. 14C described; the group of beam path deflectors with a wide field of view 28 forms a two-dimensional image 2D on the emission surface 12 of the light guide plate 10. Fig. 13A represents an example of the shape for a group of beam path deflectors with a wide field of view 28, which form the two-dimensional image 2D on the emission surface 12 of the first light guide plate 10; Fig. 13A is a top view showing the two-dimensional image 2D that forms an arrow consisting of several points. Fig. Figure 13B is a top view showing the prisms in the group of wide-field beam deflectors 28 arranged in a section to form a single point; and Fig. 13C and Fig. Figure 13D presents examples of shapes for a prism in the group of wide-field beam deflectors 28. Fig. 14A, Fig. 14B and Fig. 14C are perspective views which provide another example of modifying the shape of a prism P28a in the group of wide field-of-view beam deflectors 28.

[0089] In this case, if the arrow generated on the emission surface 12 of the light guide plate 10 is a two-dimensional image 2D, the two-dimensional image 2D that constitutes the arrow is a grouping of points ( Fig. 13A). A group of fourth beam path deflectors 28a consisting of prisms P28a is provided in a section of the rear surface 13 of the light guide plate 10; this group of fourth beam path deflectors 28a enables the light guide plate 10 to form a single point as a point image ( Fig. 13B). Furthermore, the prisms P28a serve as the fourth beam path deflectors, which constitute the group of first beam path deflectors 28a. Each of the sections provided with a group of fourth beam path deflectors 28a, 28b, 28c,... represents a group of beam path deflectors with a wide field of view 28.

[0090] The group of wide-field beam deflectors 28 can be configured into multiple sections using a group of fourth beam deflectors 28a, 28b, 28c,... Here, a group of fourth beam deflectors 28a, 28b, 28c,... consists of prisms P28a, which serve as multiple fourth beam deflectors forming a single point image. The group of fourth beam deflectors 28 can therefore be used to group the point images of a group of fourth beam deflectors 28a, 28b, 28c,... from multiple sections. Accordingly, the two-dimensional image appears to be planar.

[0091] The group of wide-field beam deflectors 28 in Fig. 13B can be found in Fig. The tetrahedral prisms P28a shown in Figure 13C are used. However, the embodiments are not limited to this. For example, the prisms can be curved tetrahedra ( Fig. 13D).

[0092] The in Fig. The group of beam path deflectors with a wide field of view 28 shown in Figure 13B can group the point images with a high directivity and display the two-dimensional image (2D). However, the embodiments are not limited to this. For example, the group of beam path deflectors with a wide field of view 28 can have a lower directivity, as shown in Figure 13B. Fig. 14A, Fig. 14B and Fig. 14C is shown. In this case, in order to display the two-dimensional image 2D in a defined area, the prisms P28a can be configured such that: the reflective surfaces of them spread light ( Fig. 14A); the tetrahedral prisms P28a are curved ( Fig. 14B); or the prisms P28a have a shape similar to that of a frustoconical prism ( Fig. 14C). Furthermore, in this case it is also necessary to ensure that the two-dimensional image 2D shown does not overlap the stereoscopic image I formed by the group of narrow-field beam deflectors 27.

[0093] The two-dimensional 2D image is independent of the angle in the wide viewing direction (i.e., the line "same position" in Fig. 15) generated at a predetermined position on the emission surface 12 of the light guide plate 10 in the optical device 1A of the embodiment. However, the embodiments are not limited to this. For example, the position at which the group of beam path deflectors with a wide field of view 28 forms the two-dimensional image 2D can be determined depending on the angle in the wide viewing direction in the optical device 1A' (the line "slight offset" in Fig. 15) will be amended.

[0094] This means that it is possible for the group of beam deflectors with a narrow field of view 27 to form a stereoscopic image I in a space and, for example, for a group of beam deflectors with a wide field of view 28 to produce two-dimensional images 2D along a wide viewing angle direction at end sections, as in Fig. Figure 16A shows that, as a result, a provided optical device 1A uses a group of beam path deflectors with a wide field of view 28 at the end section to form a two-dimensional image 2D at a position; in this way, the optical device 1A can form a two-dimensional image 2D at a fixed position regardless of the angle in the wide viewing direction.

[0095] However, beam path deflectors with a wide field of view, positioned at various locations, can form multiple two-dimensional images (2D), as shown in Fig. Figure 16B illustrates this. Here, the optical device 1A' can be configured such that the two-dimensional image 2D approaches the reference plane BL when moving from a wide viewing angle to a narrow viewing angle.

[0096] Accordingly, when the two-dimensional image 2D is formed on the emission surface 12 of the light guide plate 10, the optical device of this embodiment can change, with the two-dimensional image 2D being formed at a different position on the emission surface 12 of the light guide plate 10 while the viewing angle increases. As a result, it is possible to create a presentation effect, wherein the two-dimensional image 2D moves in accordance with a movement from a wide viewing angle to a narrow viewing angle, and wherein the two-dimensional image 2D transitions from a certain viewing angle into a stereoscopic image I.

[0097] In fact, the relationship between the viewing angle and the image-forming position in the optical device 1A, 1A' yields a pattern position curve that begins to rise at or above 45° ( Fig. 15). Accordingly, the first angle α in this embodiment of the optical device 1A, 1A' can be equal to 45° ( Fig. 17) provided that the space in a wide viewing direction is defined as corresponding to at least the first angle α and at most 90° to form the two-dimensional 2D image. Accordingly, it is possible to ensure that the stereoscopic image is not blurred at an angle in the wide viewing direction determined to be greater than or equal to the first angle α of 45° and less than 90°. More preferably, the first angle α is 50°. The stereoscopic 3D image is therefore visible up to the limit at which blurring becomes apparent. A first angle α of 45° produces a wide viewing angle with respect to the reference plane BL; this means that the wide viewing angle in this embodiment is ±45° with respect to the reference plane BL.

[0098] Accordingly, the optical device 1A of this embodiment is equipped with a light guide plate 10, which guides light entering it from the light source 2 and changes the path of the guided light, causing the light to emerge from the emission surface 12 and form an image in space. The optical device 1A of this embodiment further comprises a group of beam deflectors with a narrow field of view 27 and a group of beam deflectors with a wide field of view 28. The group of beam deflectors with a narrow field of view 27 causes an image to be formed in space in a narrow viewing direction, extending from 0° or above to below a first angle α with respect to a reference plane BL.The group of beam deflectors with a wide field of view 28 causes an image to be generated in a room in a wide viewing direction that is greater than the first angle α and less than 90° with respect to the reference plane BL. The reference plane BL is perpendicular to the emission surface 12 of the light guide plate 10 and parallel to the side surface 14. The group of beam deflectors with a narrow field of view 27 and the group of beam deflectors with a wide field of view 28 exhibit different image formation conditions.

[0099] The group of beam deflectors with a narrow field of view 27 in the optical device 1A of the embodiment forms a stereoscopic image I in a space separate from the light guide plate 10. In contrast, the group of beam deflectors with a wide field of view 28 forms a two-dimensional image 2D on the emission surface 12 of the light guide plate 10.

[0100] Furthermore, the group of beam path deflectors with a wide field of view 28 forms the two-dimensional image 2D at a predetermined position, which is not dependent on the angle in the wide viewing direction in the optical device 1A of the embodiment.

[0101] Furthermore, the group of beam path deflectors with a wide field of view 28 can form the two-dimensional image 2D at a predetermined position, which is variable depending on the angle in the wide viewing direction in the optical device 1A' of the embodiment.

[0102] As a result, it is possible to ensure that the stereoscopic image I is not blurred over a wide viewing angle. Accordingly, an optical device 1A can be provided which is capable of preventing the visibility of a stereoscopic image I in a room from deteriorating over a wide viewing direction.

[0103] An optical device 1A, 1A' according to this embodiment can therefore be used to generate a stereoscopic image I that appears along a corridor in an accommodation facility, such as in a hotel, or along a narrow passage, such as in an underground road or a connecting passage; the optical device 1A, 1A' according to this embodiment can further be used to form a stereoscopic image I to display room numbers or something similar for persons using handrails, e.g. in a hospital with elderly people or wheelchair users.

[0104] Alternatively, the stereoscopic image I can be used as a display on a device, for example to indicate the direction of an escalator (upwards or downwards); it can consist of an arrow indicating the platform numbers, e.g. for a train, or it can be a route indicator on a train door.

[0105] In this embodiment of the optical device 1A, 1A', the group of narrow-field beam deflectors 27 and the group of wide-field beam deflectors 28 include several aligned groups of secondary beam deflectors 25a, 25b, 25c,...; the several groups of secondary beam deflectors 25a, 25b, 25c,... consist of prisms P25a, P25b, P25c,..., which act as secondary beam deflectors. The several secondary beam deflectors are configured to form point images PI, which appear to form a line image LI.

[0106] In other words, the optical device 1A, 1A' is equipped with a light guide plate 10, which guides incident light in a plane parallel to the emission surface 12, and with several light-focusing sections, each light-focusing section containing an optical surface. Light guided by the light guide plate 10 is incident on an optical surface, and the optical surface causes the light to exit the emission surface 12 in a direction that converges substantially on a single convergence point or line in space, or in a direction that radiates substantially from a single convergence point or line in space. Each of the multiple light-focusing points is formed along a predetermined line in a plane parallel to the emission surface 12.The point of convergence or the line of convergence differs for each of the light-focusing sections, and grouping several of the points of convergence or lines of convergence forms an image in a space.

[0107] A point pattern PI with high light intensity can therefore be formed. The point patterns PI formed by the groups of second beam deflectors 25a, 25b, 25c,... originate from several aligned points of the groups of second beam deflectors 25a, 25b, 25c,.... Therefore, the point patterns PI are aligned as a line pattern LI, appear as such, and are thus recognizable as such.

[0108] Accordingly, the groups of second beam path deflectors 25a, 25b, 25c,... formed in the light guide plate 10 tend to act as the group of beam path deflectors with a narrow field of view 27, and the groups of beam path deflectors with a wide field of view 28 tend to produce a stereoscopic image I consisting of a line image LI with high light intensity.

[0109] In this embodiment of the optical device 1A, 1A', the group of narrow-field beam deflectors 27 and the group of wide-field beam deflectors 28 include several aligned groups of first beam deflectors 21a, 21b, 21c,...; the several groups of first beam deflectors 21a, 21b, 21c,... consist of prisms P21a, P21b, P21c,..., which act as first beam deflectors. The several first beam deflectors are configured to form line images LI that appear to form a planar image FI.

[0110] In other words, the optical device 1A, 1A' comprises a light guide plate 10, which guides light from a light source 2 in a plane parallel to the emission surface 12, and several optical deflectors. The optical deflectors redirect light that passes through the light guide plate 10, causing the light to exit the emission surface 12 and form an image in space. Each optical deflector spreads the incident light into light with an intensity distribution corresponding to an image in a direction perpendicular to the light-guiding direction of the light guide plate in a plane parallel to the emission surface 12. This causes the light to exit the emission surface 12, so that the light from the optical deflectors arranged along a direction perpendicular to the light-guiding direction spreads in a direction to form or emit an image.Alternatively, the optical device 1A, 1A' includes a light guide plate 10, which directs light from a light source 2 in a plane parallel to the emission surface 12, and several optical deflectors. The optical deflectors each deflect light passing through the light guide plate 10, causing the light to exit the emission surface 12 and form an image in space. Each of the multiple deflectors spreads the incident light two-dimensionally into light with an intensity distribution corresponding to an image; this causes the light to exit the emission surface 12, such that the light from three or more deflectors arranged on different straight lines spreads in one direction to form or emit an image.

[0111] Accordingly, the groups of first beam deflectors 21a, 21b, 21c,... formed in the light guide plate 10 tend to act as the group of beam deflectors with a narrow field of view 27, and the groups of beam deflectors with a wide field of view 28 tend to form a line image LI, which is part of a planar image FI. Furthermore, providing several aligned groups of first beam deflectors 21a, 21b, 21c,... increases the thickness of the line image LI. Thus, the line image appears to form a two-dimensional planar image FI.

[0112] Accordingly, the groups of first beam deflectors 21a, 21b, 21c,... formed in the light guide plate 10 tend to act as the group of beam deflectors with narrow field of view 27, and the groups of beam deflectors with wide field of view 28 tend to form a two-dimensional planar image FI.

[0113] Furthermore, in this embodiment of the optical device 1A, 1A', the group of narrow-field beam deflectors 27 includes a reflective surface that forms an image in a room in a narrow viewing direction, which is assumed to be at least 0° and less than a first angle α with respect to a reference plane BL. In contrast, the group of wide-field beam deflectors 28 includes prisms P28a provided with a reflective surface that forms an image in a room in a wide viewing direction, which is greater than the first angle α and less than 90° with respect to the reference plane BL.

[0114] Accordingly, separate images from the same light source 2 can be formed in a room with a narrow viewing direction or in a room with a wide viewing direction; this can occur even if the group of beam deflectors with a narrow viewing field 27 and the group of beam deflectors with a wide viewing field 28 are both provided in the light guide plate 10. Second embodiment

[0115] In the following, a further embodiment of the invention will be described with reference to Fig. 18A up to and including Fig. 19. The configurations not described in this embodiment are identical to those in the first embodiment described above. For the sake of simplicity, components previously described in the first embodiment that have an identical function are given the same reference numbers, and their explanations are therefore omitted.

[0116] The optical device 1A of the first embodiment is configured to form the two-dimensional image 2D in a room in a wide viewing direction, in order to ensure that the optical device 1A presents a clearly visible image in a room in a wide viewing direction. Meanwhile, the optical device 1B of this embodiment is configured such that the group of beam path deflectors with a wide viewing field 28 has a larger step size than the group of beam path deflectors with a narrow viewing field 27.

[0117] The configuration of an optical device 1B according to this embodiment is based on Fig. 18A and Fig. 18B described. Fig. Figure 18A is a top view showing the optical device 1A configured with the group of narrow-field beam deflectors 27, arranged with the same step size p as the group of wide-field beam deflectors 28; and Fig. Figure 18B is a top view of a configuration of an optical device, configured with the group of wide-field beam deflectors 27, arranged with a larger step size p than the group of narrow-field beam deflectors 28.

[0118] As in Fig. As shown in Figure 18A, the stereoscopic image is formed at a small distance from the emission surface 12 of the optical fiber plate 10 in a space with a narrow viewing direction that corresponds to at least 0° and is smaller than the first angle α with respect to the reference plane BL. Conversely, the stereoscopic image is formed at a large distance from the emission surface of the optical fiber plate in a space with a wide viewing direction that corresponds to at least the first angle α and is less than 90° with respect to the reference plane BL.

[0119] Here, the step size p of the group of beam path deflectors with a narrow field of view 27 is the same as the step size p of the group of beam path deflectors with a wide field of view 28 in the optical device 1A of the first embodiment ( Fig. 18A). Accordingly, the stereoscopic image in the room in a narrow viewing direction and the stereoscopic image in the room in a wide viewing direction are formed with the same resolution.

[0120] Consequently, blurring is evident for a stereoscopic image formed in a room with a wide viewing direction when stereoscopic images of the same resolution are formed in the same room with a wide viewing direction and in the same room with a narrow viewing direction. This is because the group of beam path deflectors with a wide viewing field 28 tends the orientation of the pattern shape used for the stereoscopic image in the room with a wide viewing direction.

[0121] Accordingly, the optical device 1B of this embodiment is configured such that the step size p of the group of beam path deflectors with a wide field of view 28 is larger than the step size p of the group of beam path deflectors with a narrow field of view 27 ( Fig. 18B).

[0122] The optical device 1B of this embodiment therefore forms a stereoscopic image in the room in a wide viewing direction, which has a lower resolution than the stereoscopic image in the room in a narrow viewing direction. The blurriness of the stereoscopic image in the room in a wide viewing direction is therefore less noticeable.

[0123] Accordingly, an optical device 1B can be provided which is capable of preventing the visibility of a stereoscopic image in a room from deteriorating in a wide viewing direction.

[0124] Fig. Figure 19 is a graph showing the relationship between the viewing angle of the optical device 1B and the step size p for the group of beam path deflectors with a wide viewing field 28 and the group of beam path deflectors with a narrow viewing field 27. As can be seen from the graph, the first angle α is preferably 45° and more preferably 50° for the optical device 1B of this embodiment. Third embodiment

[0125] In the following, a further embodiment of the invention will be described with reference to Fig. 20A up to and including Fig. 22. The configurations not described in this embodiment are identical to those in the first and second embodiments described above. For the sake of simplicity, components previously described in the first and second embodiments that have an identical function are given the same reference numbers, and their explanations are omitted.

[0126] The optical device 1C of this embodiment is configured such that the group of beam path deflectors with narrow field of view 27 and the group of beam path deflectors with wide field of view 28 provide parallax images.

[0127] The configuration of an optical device 1C according to this embodiment is based on: Fig. 20A, Fig. 20B and Fig. 20°C up to and including Fig. 22 described. Fig. 20A is a top view showing viewpoints fixed at uniform intervals along a horizontal direction; and Fig. 20B is a perspective view generated from parallax images arranged with a uniform step size, when the viewing points have uniform step sizes along the horizontal direction. Fig. 20C is a cross-sectional view of the xz-plane, representing a stereoscopic image generated from parallax images with a uniform step size.

[0128] Typically, a uniform step size is produced when parallax images are used to form a stereoscopic image I ( Fig. 20A). Accordingly, the parallax images are also formed with a uniform step size ( Fig. 20B and Fig. 20C). Similar to the optical device 1A of the previous embodiment, the optical device 1B forms parallax images with the same resolution in the space in a wide viewing direction and in the space in a narrow viewing direction. This results in the parallax images formed in the space in a wide viewing direction being blurred.

[0129] Accordingly, in the optical device 1C of this embodiment, several pairs of parallax images are horizontally aligned, each pair consisting of a parallax image for the right eye and a parallax image for the left eye; at the same time, for example, the group of beam path deflectors with a wide field of view 28 forms adjacent parallax images, so that the step size increases.

[0130] More precisely, a uniform step size is generated when parallax images are used to form a stereoscopic image I ( Fig. 21A). The parallax images are also designed in such a way that the step size between adjacent parallax images also increases with increasing viewing angle ( Fig. 21B and Fig. 21C).

[0131] Accordingly, an optical device can be provided which, even in the case of a parallax image, is able to prevent the visibility of a stereoscopic image in a room from being deteriorated in a wide viewing direction.

[0132] The embodiment is not limited to this and other methods can be used. For example, an optical device 1C' can be considered which forms a two-dimensional image 2D in an area outside the defined wide viewing angle.

[0133] In this case, an optical device 1C' can be provided which, even in the case of a parallax image, is able to prevent the visibility of a stereoscopic image in a room in a wide viewing direction from being deteriorated, similar to the optical device 1A of the first embodiment. Fourth embodiment

[0134] In the following, a further embodiment of the invention will be described with reference to Fig. 23. The configurations not described in this embodiment are identical to those in the first through third embodiments described above. For the sake of simplicity, components previously described in the first through third embodiments that have an identical function are given the same reference numbers, and their explanations are omitted.

[0135] An optical device 1D of this embodiment, configured with the light source 2, installed at a corner of the light guide plate 10.

[0136] The configuration of an optical device 1D according to this embodiment is based on Fig. 23A and Fig. 23B described. Fig. 23A and Fig. Figure 23B are top views showing a configuration of the optical device 1D of the fourth embodiment, wherein the light source 2 is arranged at a corner of the light guide plate 10.

[0137] The direction of the narrow viewing angle and the direction of the wide viewing angle are defined in the optical device 1A-1D from the first to the fourth embodiment, assuming a viewer is moving and the reference plane BL is perpendicular to a horizontal surface.

[0138] The optical device 1D can be configured such that the light source 2 is located on a surface at either its top or bottom. In this case, the group of wide-field beam deflectors 28 must strongly deflect light propagating vertically from the light source 2, so that when reflected by the group of wide-field beam deflectors 28, the light exits horizontally in the wide viewing direction. This means that the light intensity decreases in the wide viewing direction.

[0139] In contrast, light from the light source 2 can laterally illuminate the group of beam deflectors with a wide field of view 28 and the group of beam deflectors with a narrow field of view 27; in this case, there is an interaction between the light source 2 and neighboring groups of beam deflectors. As a result, a rather unsuitable stereoscopic image is obtained.

[0140] Accordingly, the light source 2 in the optical device 1D of this embodiment is configured such that it illuminates the group of beam path deflectors with narrow field of view 27 and the group of beam path deflectors with wide field of view 28 from a direction that is inclined with respect to the reference plane BL ( Fig. 23A).

[0141] Therefore, there is no interference between adjacent groups of beam deflectors, and the angle at which light from light source 2 must be deflected is also reduced. Consequently, it is possible to increase the light intensity of light reflected towards the wide viewing direction.

[0142] The optical device 1D of this embodiment can also efficiently measure the in Fig. 15 two-dimensional images shown can be shifted in 2D by installing the light source 2 at a corner of the light guide plate 10 ( Fig. 23B). Fifth embodiment

[0143] In the following, a further embodiment of the invention will be described with reference to Fig. 24A up to and including Fig. 27B. The configurations not described in this embodiment are identical to those in the first through fourth embodiments described above. For the sake of simplicity, components previously described in the first through fourth embodiments that have an identical function are given the same reference numbers, and their explanations are omitted.

[0144] The optical device 1E of this embodiment presents a stereoscopic image I which has a thickness.

[0145] The configuration of an optical device 1E according to this embodiment is based on Fig. 24A and Fig. 24B up to and including Fig. 27A and Fig. 27B described. Fig. 24A is a top view showing the stereoscopic image I as viewed from a narrow viewing angle; and Fig. 24B is a perspective view showing how the stereoscopic image I appears when viewed from the narrow viewing direction. Fig. 25A is a top view showing the stereoscopic image I as viewed from a wide viewing angle; and Fig. Figure 25B is a perspective view showing the appearance of stereoscopic image I when viewed from the wide viewing direction. Fig. Figure 26A is a top view of the optical device 1E of this embodiment, showing the stereoscopic image I as viewed from a narrow viewing angle; and Fig. Figure 26B is a perspective view showing how the stereoscopic image I appears when viewed from the narrow viewing direction. Fig. 27A is a top view of the optical device 1E of this embodiment, showing the stereoscopic image I as viewed from a wide viewing angle; and Fig. Figure 27B is a perspective view showing the appearance of stereoscopic image I when viewed from the wide viewing direction.

[0146] For example, a stereoscopic image I consisting of an arrow perpendicular to the light guide plate 10 ( Fig. 24A) be formed; the stereoscopic image I tends to exhibit three-dimensionality ( Fig. 24B), when viewed from below from a narrow viewing angle. In contrast, the stereoscopic image I, which consists of an arrow, is perpendicular to the light guide plate 10 ( Fig. 25A); however, the stereoscopic image I loses its three-dimensionality ( Fig. 25B), when viewed diagonally from below from a wide viewing angle.

[0147] Accordingly, the optical device 1E of this embodiment represents a stereoscopic image I that has thickness. Preferably, the stereoscopic image I has the appearance of thickness, particularly from a wide viewing direction. Here, a stereoscopic image I consisting of an arrow can be projected perpendicular to the light guide plate 10 ( Fig. 26A) be formed; the stereoscopic image I tends to exhibit three-dimensionality ( Fig. 26B), when viewed from below from a narrow viewing angle. Furthermore, the stereoscopic image I, which consists of an arrow, is perpendicular to the light guide plate 10 ( Fig. 27A) formed; when viewed diagonally from below from a wide viewing angle, a line along the thickness direction indicates the shape of the stereoscopic image I ( Fig.27B). Accordingly, the image shown can easily be recognized as a stereoscopic image I consisting of an arrow formed perpendicular to the light guide plate 10.

[0148] The present invention is not limited to the embodiments described above and can be modified in various ways while remaining within the scope of the claims. The technical means disclosed in each of the various embodiments can be combined as appropriate, and an embodiment obtained in this way remains within the technical scope of the present invention.

[0149] Accordingly, as previously described, in order to address the above-mentioned problems, an optical device is configured according to one aspect of the invention, such that the optical device comprises: a light guide plate configured to guide light entering it from a light source, to change the path of the guided light, and to cause light to emerge from an emitting surface of the light guide plate, thus forming an image in space; a group of narrow-field beam deflectors configured to produce an image in space in a narrow viewing direction, which is assumed to be an angle greater than 0° and less than a first angle with respect to a reference plane that is perpendicular to the emitting surface and parallel to a side surface of the light guide plate;and a group of wide-field beam deflectors configured to produce an image in a room in a wide viewing direction, which is assumed to be an angle greater than the first angle and less than 90° with respect to the reference plane; wherein the narrow-field beam deflectors group and the wide-field beam deflectors group have different image formation conditions.

[0150] The optical device is equipped with a light guide plate that directs light entering it from the light source and changes the path of the light thus guided, causing the light to exit the emission surface and form an image in space.

[0151] The visibility of a stereoscopic image formed with this optical device deteriorates because the stereoscopic image is blurred over a wide viewing angle when the optical device forms the stereoscopic image.

[0152] To address this, an optical device according to one aspect of the invention comprises a group of narrow-field beam deflectors configured to produce an image in a space in a narrow viewing direction, which is assumed to be an angle greater than 0° and less than a first angle with respect to a reference plane that is perpendicular to the emitting surface and parallel to a side surface of the light guide plate; and a group of wide-field beam deflectors configured to produce an image in a space in a wide viewing direction, which is assumed to be an angle greater than the first angle and less than 90° with respect to the reference plane; and wherein the group of narrow-field beam deflectors and the group of wide-field beam deflectors have different image formation conditions.

[0153] As a result, it is possible to ensure that the stereoscopic image is not blurred over a wide viewing angle. Therefore, an optical device can be provided that is capable of preventing the visibility of a stereoscopic image in a room from deteriorating over a wide viewing direction.

[0154] In the optical device according to one aspect of the invention, the group of beam deflectors with a narrow field of view forms a stereoscopic image in a space different from the light guide plate, while the group of beam deflectors with a wide field of view forms a two-dimensional image on the emission surface of the light guide plate.

[0155] In the optical device according to one aspect of the invention, the group of beam path deflectors with a wide field of view forms the two-dimensional image at a location that is fixed and independent of the angle in the wide viewing direction.

[0156] Here, the group of beam deflectors with a wide field of view forms an image in a room in a wide viewing direction, which is assumed to be an angle greater than the first angle and less than 90° with respect to a reference plane.

[0157] Accordingly, the two-dimensional image is formed in a space within a wide viewing direction, thus enabling the display of a clear image. A stereoscopic image formed in a space within a wide viewing direction is hardly distinguishable from a two-dimensional image, even if the stereoscopic image is not blurry. This means that viewing a sharp two-dimensional image causes less discomfort than viewing a blurry stereoscopic image.

[0158] Accordingly, an optical device can be provided that is capable of preventing the visibility of a stereoscopic image in a room from deteriorating in a wide viewing direction.

[0159] In the optical device according to an aspect of the invention, the group of beam path deflectors with a wide field of view forms the two-dimensional image at a location that varies depending on the angle in the wide viewing direction.

[0160] Accordingly, when forming the two-dimensional image on the emission surface of the optical fiber, the optical device can change, whereby the two-dimensional image is formed at a different position on the emission surface of the optical fiber as the viewing angle increases. As a result, it is possible to create a presentation effect, whereby the two-dimensional image moves in accordance with a movement from a wide viewing angle to a narrow viewing angle, and whereby the two-dimensional image transitions from a certain viewing angle into a stereoscopic image I.

[0161] In the optical device according to one aspect of the invention, the group of beam path deflectors with a wide field of view is arranged with a larger step size than the group of beam path deflectors with a narrow field of view.

[0162] In other words, the stereoscopic image is formed at a small distance from the emission surface of the optical fiber in a room with a narrow viewing direction that is at least 0° and smaller than the first angle with respect to the reference plane. Conversely, the stereoscopic image is formed at a large distance from the emission surface of the optical fiber in a room with a wide viewing direction that is at least equal to the first angle α and less than 90° with respect to the reference plane.

[0163] Consequently, blurring is obvious for a stereoscopic image formed in a room in a wide viewing direction when stereoscopic images of the same resolution are formed in the room in a wide viewing direction and in the room in a narrow viewing direction.

[0164] According to one aspect of the invention, the group of beam deflectors with a wide field of view is arranged with a larger step size than the group of beam deflectors with a narrow field of view. Consequently, the stereoscopic image in the room has a lower resolution in a wide viewing direction than the stereoscopic image in the room in a narrow viewing direction. The blurring of the stereoscopic image in the room in a wide viewing direction is therefore less noticeable.

[0165] Accordingly, an optical device is able to prevent the visibility of a stereoscopic image in a room from deteriorating in a wide viewing direction using this method.

[0166] In the optical device according to one aspect of the invention, the group of beam deflectors with a narrow field of view and the group of beam deflectors with a wide field of view comprise several aligned groups of second beam deflectors, consisting of several second beam deflectors, configured to form a point image, wherein the second beam deflectors appear to form a line image.

[0167] Accordingly, a point image with high light intensity is formed, since each of the second beam deflectors forms an individual point image. Because several groups of second beam deflectors are present, the point images formed by these groups appear as a line image when aligned and are perceived as such.

[0168] Accordingly, the groups of second beam deflectors formed in the light guide plate tend to act as the group of beam deflectors with a narrow field of view, and the groups of beam deflectors with a wide field of view tend to produce a stereoscopic image consisting of a line image with high light intensity.

[0169] In the optical device according to one aspect of the invention, the group of beam deflectors with a narrow field of view and the group of beam deflectors with a wide field of view comprise several aligned groups of first beam deflectors, consisting of several first beam deflectors, configured to form a line image, wherein the first beam deflectors appear to form a planar image.

[0170] Accordingly, the groups of first beam deflectors formed in the optical fiber plate tend to act as the group of beam deflectors with a narrow field of view, and the groups of beam deflectors with a wide field of view tend to form a line pattern that is part of a planar image. The multiple groups of first beam deflectors thus increase the thickness of the line pattern. Therefore, the line pattern appears to form a two-dimensional planar image.

[0171] Accordingly, the groups of first beam deflectors formed in the light guide plate tend to act as the group of beam deflectors with a narrow field of view, and the groups of beam deflectors with a wide field of view tend to form a two-dimensional planar image FI.

[0172] In the optical device according to one aspect of the invention, the group of wide-field beam deflectors comprises groups of fourth beam deflectors in several sections, wherein a single section comprises: a group of fourth beam deflectors consisting of several fourth beam deflectors; a group of fourth beam deflectors configured to form a single point image; and wherein the wide-field beam deflectors group in the optical device is configured to group the point images, making the two-dimensional image appear to be a planar image. This allows a more concrete two-dimensional image to be formed.

[0173] In the optical device according to one aspect of the invention, the group of beam deflectors with a narrow field of view includes reflective surfaces configured to produce an image in a room in a narrow viewing direction, which is assumed to be an angle greater than 0° and less than a first angle with respect to the reference plane, and wherein the group of beam deflectors with a wide field of view includes reflective surfaces configured to produce an image in a room in a wide viewing direction, which is assumed to be at least as large as the first angle and less than 90° with respect to the reference plane.

[0174] Accordingly, separate images from the same light source can be formed in a room with a narrow viewing direction or in a room with a wide viewing direction; this can occur even if the group of beam deflectors with a narrow viewing field and the group of beam deflectors with a wide viewing field are both provided in the light guide plate.

[0175] In the optical device according to one aspect of the invention, the image consists of parallax images and wherein several pairs of the parallax images, each pair consisting of a parallax image for the right eye and a parallax image for the left eye, are horizontally aligned.

[0176] Accordingly, an optical device can be provided which, even in the case of a parallax image, is able to prevent the visibility of a stereoscopic image in a room from being deteriorated in a wide viewing direction.

[0177] In the above optical device according to an aspect of the invention, the group of beam deflectors with a narrow field of view and the group of beam deflectors with a wide field of view are illuminated with light from a direction oblique to the reference plane.

[0178] That is to say, the direction of the narrow viewing angle and the direction of the wide viewing angle are defined in this aspect of the present invention, assuming a viewer is moving and the reference plane is perpendicular to a horizontal surface.

[0179] The optical device can be configured such that the light source is located on a surface at either the top or bottom. In this case, the group of wide-field beam deflectors must strongly deflect light propagating vertically from the light source, so that when reflected by the group of wide-field beam deflectors, the light exits horizontally in the wide viewing direction. Consequently, the light intensity decreases in the wide viewing direction.

[0180] In contrast, light from the light source can laterally illuminate the group of beam deflectors with a wide field of view and the group of beam deflectors with a narrow field of view; in this case, the light source interacts with neighboring groups of beam deflectors. The result is a rather unsuitable stereoscopic image.

[0181] According to this, in the optical device above, according to an aspect of the invention, the group of beam deflectors with a narrow field of view and the group of beam deflectors with a wide field of view are illuminated with light from a direction oblique to the reference plane.

[0182] Therefore, there is no interference between adjacent groups of beam deflectors, and the angle at which light must be deflected from the light source is also reduced. Consequently, it is possible to increase the light intensity of light reflected towards the broad viewing direction.

Claims

[1] Optical device (1A) comprising: a light guide plate (10) configured to guide light entering it from a light source (2), to change the path of the guided light and to cause this light to emerge from an emission surface (12) of the light guide plate (10) and thus form an image in a space; a group of narrow-field beam deflectors (27) configured to produce an image in a room in a narrow viewing direction, which is assumed to be an angle greater than 0° and less than a first angle with respect to a reference plane that is perpendicular to the emitting surface (12) and parallel to a side surface of the light guide plate; and a group of wide-field beam deflectors (28) configured to produce an image in a room in a wide viewing direction, which is assumed to be an angle greater than the first angle and less than 90° with respect to the reference plane; wherein the group of beam path deflectors with narrow field of view (27) and the group of beam path deflectors with wide field of view (28) exhibit different image formation conditions, wherein the group of beam path deflectors with narrow field of view (27) forms a stereoscopic image in a space different from the light guide plate (10), while the group of beam path deflectors with wide field of view (28) forms a two-dimensional image on the emission surface of the light guide plate (10), and wherein the group of beam path deflectors with wide field of view (28) is arranged on a surface of the light guide plate (10) whose surface is opposite the emission surface (12). [2] Optical device (1A) according to claim 1, wherein the group of beam path deflectors with wide field of view (28) is configured to form the two-dimensional image at a location that is fixed and independent of the angle in the wide viewing direction. [3] Optical device (1A) according to claim 1, wherein the group of beam path deflectors with wide field of view (28) is configured to form the two-dimensional image at a location which is variable depending on the angle in the wide viewing direction. [4] Optical device (1A) according to any one of claims 1 to 3, wherein: the group of wide-field beam deflectors (28) comprises groups of fourth beam deflectors (28a - 28c) in multiple sections, wherein a single section comprises: a group of fourth beam deflectors (28a - 28c) composed of multiple fourth beam deflectors (28a - 28c), a group of fourth beam deflectors (28a - 28c) configured to form a single point image; and wherein the group of wide-field beam deflectors (28) in the optical device (1A) is configured to group the point images, thereby making the two-dimensional image appear to provide a planar image. [5] Optical device (1A) according to any one of claims 1 to 3, wherein: the group of beam deflectors with narrow field of view (27) comprises reflective surfaces (f1 - f5) configured to produce an image in a room in a narrow viewing direction, which is assumed to be an angle greater than 0° and less than a first angle with respect to the reference plane; and the group of beam deflectors with wide field of view (28) comprises reflective surfaces (f1 - f5) configured to produce an image in a room in a wide viewing direction, which is assumed to be an angle greater than the first angle and less than 90° with respect to the reference plane. [6] Optical device according to one of claims 1 to 3, wherein: the group of beam deflectors with narrow field of view (27) and the group of beam deflectors with wide field of view (28) are illuminated with light from a direction oblique to the reference plane. [7] Optical apparatus (1A) comprising: a light guide plate (10) configured to guide light entering it from a light source (2), to change the path of the guided light and to cause this light to emerge from an emission surface (12) of the light guide plate (10) and thus form an image in a space; a group of narrow-field beam deflectors (27) configured to produce an image in a room in a narrow viewing direction, which is assumed to be an angle greater than 0° and less than a first angle with respect to a reference plane that is perpendicular to the emitting surface (12) and parallel to a side surface of the light guide plate; and a group of wide-field beam deflectors (28) configured to produce an image in a room in a wide viewing direction, which is assumed to be an angle greater than the first angle and less than 90° with respect to the reference plane; and wherein the group of beam path deflectors with narrow field of view (27) and the group of beam path deflectors with wide field of view (28) exhibit different image formation conditions, wherein the group of beam deflectors with a wide field of view (28) is arranged with a larger step size than the group of beam deflectors with a narrow field of view (27). [8] Optical device according to claim 7, wherein: the image consists of parallax images and wherein several pairs of the parallax images, each pair consisting of a parallax image for the right eye and a parallax image for the left eye, are horizontally aligned. [9] Optical apparatus (1A) comprising: a light guide plate (10) configured to guide light entering it from a light source (2), to change the path of the guided light and to cause this light to emerge from an emission surface (12) of the light guide plate (10) and thus form an image in a space; a group of narrow-field beam deflectors (27) configured to produce an image in a room in a narrow viewing direction, which is assumed to be an angle greater than 0° and less than a first angle with respect to a reference plane that is perpendicular to the emitting surface (12) and parallel to a side surface of the light guide plate; and a group of wide-field beam deflectors (28) configured to produce an image in a room in a wide viewing direction, which is assumed to be an angle greater than the first angle and less than 90° with respect to the reference plane; wherein the group of beam path deflectors with a narrow field of view (27) and the group of beam path deflectors with a wide field of view (28) exhibit different image formation conditions, and wherein: the group of beam deflectors with narrow field of view (27) and the group of beam deflectors with wide field of view (28) contain several aligned groups of second beam deflectors (25a - 25c), formed from several second beam deflectors (25a - 25c), configured to form a point image (PI), wherein the second beam deflectors (25a - 25c) appear to form a line image. [10] Optical device (1A) comprising: a light guide plate (10) configured to guide light entering it from a light source (2), to change the path of the guided light and to cause this light to emerge from an emission surface (12) of the light guide plate (10) and thus form an image in a space; a group of narrow-field beam deflectors (27) configured to produce an image in a room in a narrow viewing direction, which is assumed to be an angle greater than 0° and less than a first angle with respect to a reference plane that is perpendicular to the emitting surface (12) and parallel to a side surface of the light guide plate; and a group of wide-field beam deflectors (28) configured to produce an image in a room in a wide viewing direction, which is assumed to be an angle greater than the first angle and less than 90° with respect to the reference plane; wherein the group of beam path deflectors with a narrow field of view (27) and the group of beam path deflectors with a wide field of view (28) exhibit different image formation conditions, and wherein: the group of beam deflectors with narrow field of view (27) and the group of beam deflectors with wide field of view (28) contain several aligned groups of first beam deflectors (21a - 21c), formed from several first beam deflectors (21a - 21c), configured to form a line image, wherein the first beam deflectors (21a - 21c) appear to form a planar image.

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