Projection optical system and glasses-type terminal

Abstract

This projection optical system (50) comprises: a projection substrate (100), which has an optical waveguide part (200), and is for projecting an image light onto a second surface that is on the opposite side from a first surface while transmitting to the second surface at least a portion of light that is incident to the first surface; and a diffracted light reduction plate (310), which is provided on the first-surface side of the projection substrate (100) relative to the optical waveguide part (200), with an air layer therebetween, covers at least a portion of the optical waveguide part (200), and reduces diffracted light occurring when incident light having a prescribed incidence angle from the first surface of the projection substrate (100) is diffracted by the optical waveguide part (200) and travels in the direction in which the image light is emitted. The optical waveguide part (200) guides at least a portion of the projection light for projecting the image light, and emits the image light from the second surface.

Description

Projection optical system and eyeglass-type terminal

[0001] The present invention relates to a projection optical system and an eyeglass-type terminal.

[0002] 2. Description of the Related Art Conventionally, there are known eyeglass-type devices, head-mounted displays, and the like that display two-dimensional images for a user to observe using an optical system including a waveguide or the like (see, for example, Patent Document 1).

[0003] JP 2017-207686 A International Publication No. 2015 / 111523

[0004] In such devices, the optical system is often complex because it must be installed in a limited space. Also, if the optical system has a diffraction grating or the like, light incident at a certain angle may be diffracted and enter the user's eye.

[0005] Therefore, the present invention has been made in consideration of these points, and aims to provide a device that displays two-dimensional images for a user to observe, which is capable of reducing diffracted light traveling toward the user's eyes with a simple configuration.

[0006] In a first aspect of the present invention, there is provided a projection optical system comprising: a projection substrate having an optical waveguide, which transmits at least a portion of light incident from a first surface to a second surface opposite the first surface, while projecting image light onto the second surface; and a diffracted light reduction plate, which is provided on the first surface side or the second surface side of the projection substrate with respect to the optical waveguide via an air layer, which covers at least a portion of the optical waveguide and reduces diffracted light that is incident from the first surface of the projection substrate at a predetermined incident angle and is diffracted by the optical waveguide in a direction from which the image light is emitted, wherein the optical waveguide guides at least a portion of the projection light for projecting the image light, and the diffracted light reduction plate emits the image light from the second surface.

[0007] The diffracted light reduction plate may include a protective substrate disposed opposite the first surface or the second surface of the projection substrate, a polarizing filter disposed on one of the third surface of the protective substrate opposite the projection substrate and the fourth surface facing the projection substrate, and reducing P waves parallel to the plane of incidence of the incident light that is incident on the diffracted light reduction plate, and an infrared cut filter disposed on the surface of the protective substrate opposite the surface on which the polarizing filter is disposed, and reducing light in the infrared region of the incident light.

[0008] The diffracted light reduction plate may be arranged opposite the first surface or the second surface of the projection substrate and may have a polarizing filter that reduces P waves parallel to the plane of incidence of the incident light that is incident on the diffracted light reduction plate.

[0009] The diffracted light reduction plate may include a protective substrate disposed opposite the first surface or the second surface of the projection substrate, and a polarizing film coated on at least one of a third surface of the protective substrate opposite the projection substrate and a fourth surface facing the projection substrate, the polarizing film reducing P waves parallel to the plane of incidence of the incident light incident on the diffracted light reduction plate.

[0010] The diffracted light reduction plate may include a protective substrate provided opposite the first surface or the second surface of the projection substrate, and a light control filter provided on at least one of a third surface of the protective substrate opposite the projection substrate and a fourth surface facing the projection substrate, the light control filter allowing the incident light incident on the diffracted light reduction plate at an incident angle within a first angle range to pass to the light guide unit, and diffusing the incident light incident on the diffracted light reduction plate at an incident angle within a second angle range different from the first angle range, thereby attenuating the amount of light that travels straight and reaches the light guide unit compared to when the incident light is incident at an incident angle within the first angle range.

[0011] The light control filter may be formed by depositing a filter material on at least one of the third surface and the fourth surface of the protection substrate. The second angle range of the light control filter may include the predetermined angle of incidence of the incident light, which is incident from the first surface of the projection substrate and causes the optical waveguide unit to generate the diffracted light.

[0012] The diffracted light reducing plate may be provided in a range including a position above the optical waveguide when the eyeglass-type terminal including the projection optical system is worn to cover the user's eyes. The diffracted light reducing plate may be provided in a range above a lower end of the optical waveguide when the eyeglass-type terminal including the projection optical system is worn to cover the user's eyes.

[0013] The optical waveguide section has an incident region including an incident diffraction grating into which projection light for projecting the image light is incident and which guides the incident projection light into the interior of the projection substrate, and an exit region including an exit diffraction grating which guides at least a portion of the projection light incident from the incident region and outputs it from the second surface as the image light, and the diffracted light reduction plate may cover at least a portion of the exit diffraction grating.

[0014] The optical waveguide may further have an intermediate region that includes an intermediate diffraction grating and guides a portion of the projection light incident from the entrance region toward the exit region, and the entrance diffraction grating may have a plurality of first groove portions formed at a first period, the intermediate diffraction grating may have a plurality of second groove portions formed at a second period, and the exit diffraction grating may have a plurality of third groove portions formed at a third period.

[0015] In a second aspect of the present invention, there is provided a glasses-type terminal worn by a user, the glasses-type terminal comprising: the projection optical system of the first aspect, which is provided as at least one of a lens for the user's right eye and a lens for the left eye, and which projects the image light onto the second surface while transmitting at least a portion of the light incident from the first surface to the user's eye; a frame that fixes the projection optical system; and a projection unit that is provided on the frame and irradiates the projection light onto an entrance area of ​​the optical waveguide unit of the projection substrate so as to project the image light onto an exit area of ​​the optical waveguide unit.

[0016] The projection unit may have a polarization adjustment unit that adjusts the polarization direction of the projection light that is irradiated onto the incident area, and the diffracted light reduction plate of the projection optical system may be arranged opposite the first surface of the projection substrate, and the polarization adjustment unit may adjust the polarization direction of the projection light so that the polarization direction of the image light matches the polarization direction of the light reduced by the diffracted light reduction plate.

[0017] The projection unit may have a polarization adjustment unit that adjusts the polarization direction of the projection light that is irradiated onto the incident area, and the diffracted light reduction plate of the projection optical system may be arranged opposite the second surface of the projection substrate, and the polarization adjustment unit may adjust the polarization direction of the projection light so that the polarization direction of the image light matches the polarization direction of the light transmitted by the diffracted light reduction plate.

[0018] A plurality of projection substrates are fixed to the frame, and the diffracted light reduction plate is provided on the opposite side of one of the plurality of projection substrates from the user, or between the one projection substrate and the user, and the projection unit irradiates the projection light of different wavelengths onto the incident areas provided on each of the plurality of projection substrates, and the exit areas provided on each of the plurality of projection substrates at least partially overlap in a planar view, and the image light corresponding to the projection light irradiated from the projection unit onto each of the plurality of incident areas may be emitted from the second surfaces of the plurality of projection substrates to the eyes of the user, respectively.

[0019] The projection unit has a polarization adjustment unit that adjusts the polarization direction of at least one of the multiple projection lights that are irradiated onto the incident area, and the diffracted light reduction plate of the projection optical system is provided on the opposite side of the multiple projection substrates from the user, and the polarization adjustment unit may adjust the polarization direction of the projection light so that the polarization direction of at least one of the multiple image lights matches the polarization direction of the light reduced by the diffracted light reduction plate.

[0020] The projection unit may have a polarization adjustment unit that adjusts the polarization direction of at least one of the multiple projection lights that are irradiated onto the incident area, and the diffracted light reduction plate of the projection optical system may be provided between one of the multiple projection substrates and the user, and the polarization adjustment unit may adjust the polarization direction of the projection light so that the polarization direction of the image light emitted by the one projection substrate among the multiple image lights matches the polarization direction of the light transmitted by the diffracted light reduction plate.

[0021] According to the present invention, it is possible to reduce diffracted light traveling toward the user's eyes with a simple configuration.

[0022] 1 shows a first configuration example of the eyeglasses-type terminal 10 according to the present embodiment. FIG. 2 shows an outline of the optical path of projection light in the eyeglasses-type terminal 10 according to the present embodiment. FIG. 3 shows an outline of the optical path of projection light in the projection substrate 100 according to the present embodiment. FIG. 4 shows an example of projection light irradiated onto the projection substrate 100 by the projection unit 120 according to the present embodiment, and image light emitted from the projection substrate 100. FIG. 5 shows an example of the configuration of the projection substrate 100 according to the present embodiment. FIG. 6 shows an example of the configuration of the eyeglasses-type terminal 10 according to the present embodiment. FIG. 7 shows an example of the transmittance characteristics of the light control filter 410 according to the present embodiment.

[0023] <First Configuration Example of Glasses-Type Terminal 10> Fig. 1 shows a first configuration example of the glasses-type terminal 10 according to this embodiment. In this embodiment, three mutually orthogonal axes are defined as an X-axis, a Y-axis, and a Z-axis. The glasses-type terminal 10 is, for example, a wearable device worn by a user. The glasses-type terminal 10 projects image light onto a display area provided on a projection board 100 while allowing the user to observe a scene through the glasses. The glasses-type terminal 10 includes a projection optical system 50, a frame 110, and a projection unit 120.

[0024] The projection optical system 50 includes a projection substrate 100 and a diffracted light reducing plate 310. In Fig. 1, only the projection substrate 100 of the projection optical system 50 is shown, and the diffracted light reducing plate 310 is omitted. The diffracted light reducing plate 310 will be described later.

[0025] The projection board 100 has an optical waveguide 200, and transmits at least a portion of light incident from a first surface to a user's eye while projecting image light onto a second surface. Here, the first surface of the projection board 100 is a surface that faces away from a user when the user wears the eyeglasses-type terminal 10. Furthermore, the second surface of the projection board 100 is a surface that faces a user when the user wears the eyeglasses-type terminal 10. Fig. 1 shows an example in which the first and second surfaces of the projection board 100 are arranged approximately parallel to the XY plane.

[0026] The projection substrate 100 is, for example, a glass substrate on which an optical waveguide 200 is formed. The optical waveguide 200 guides at least a portion of the projection light incident on a second surface of the projection substrate 100 to project the image light, and outputs the light as the image light from the second surface. The projection substrate 100 will be described later.

[0027] The frame 110 fixes the projection optical system 50. The frame 110 is provided with the projection optical system 50 as at least one of a lens for the user's right eye and a lens for the user's left eye. Fig. 1 shows an example in which the frame 110 is provided with a projection optical system 50a as a lens for the user's right eye and a projection optical system 50b as a lens for the user's left eye.

[0028] Alternatively, the frame 110 may be provided with one projection optical system 50 as a lens for the user's right eye or left eye. The frame 110 may also be provided with one projection optical system 50 as lenses for both eyes of the user. In this case, the frame 110 may have a goggle shape. The frame 110 has temples, a strap, and other components that allow the user to wear the eyeglass-type terminal 10.

[0029] The projection unit 120 is provided on the frame 110 and irradiates the projection optical system 50 with projection light for projecting image light onto the projection substrate 100. One or more such projection units 120 are provided on the frame 110. Fig. 1 shows an example in which a projection unit 120a for irradiating the projection optical system 50a (projection substrate 100a) with projection light L1 and a projection unit 120b for irradiating the projection optical system 50b (projection substrate 100b) with projection light L2 are provided on the frame 110.

[0030] The projection unit 120 may be provided at a portion of the frame 110 where the projection optical system 50 is fixed, or may be provided at a temple or the like of the frame 110. It is desirable that the projection unit 120 be provided so as to be integrated with the frame 110. For example, the projection unit 120 irradiates the projection optical system 50 with projection light including one wavelength, allowing the user to observe a monochromatic image. Alternatively, the projection unit 120 may irradiate the projection optical system 50 with projection light including multiple wavelengths, allowing the user to observe an image including multiple colors.

[0031] The following describes such a projection optical system 50. First, the operation of the projection substrate 100 of the projection optical system 50 will be described, and the diffracted light reducing plate 310 will be described later.

[0032] 2 shows an outline of the optical path of projection light in the eyeglass-type terminal 10 according to this embodiment. The projection unit 120 irradiates the projection light onto an incident region 210 of the optical waveguide unit 200 of the projection substrate 100. The incident region 210 guides the projection light within the substrate of the projection substrate 100. At least a portion of the projection light guided within the substrate is emitted as image light from an exit region 230 of the optical waveguide unit 200. The incident region 210 and the exit region 230 will be described later.

[0033] 3 shows an outline of the optical path of projection light on the projection substrate 100 according to this embodiment. As will be described later, the optical waveguide unit 200 has an incident region 210, an intermediate region 220, and an exit region 230. Projection light L enters the incident region 210, passes through the intermediate region 220, and exits from the exit region 230 as image light P. The intermediate region 220 guides the projection light L part by part to the exit region 230 as the projection light L travels away from the incident region 210.

[0034] Similarly, as the projection light L travels away from the intermediate region 220, the emission region 230 also emits a portion of the projection light L as part of the image light P. In this way, the projection substrate 100 emits the projection light L that has entered the entrance region 210 from the emission region 230 as image light P.

[0035] Consider an example in which the intermediate region 220 guides the projection light L to the emission region 230 at a constant rate throughout the entire area of ​​the intermediate region 220. In this case, the amount of the projection light L decreases as the projection light L travels away from the entrance region 210, and therefore the intensity of the projection light L incident on the emission region 230 from the intermediate region 220 may differ depending on the distance from the entrance region 210.

[0036] Similarly, consider an example in which the output region 230 outputs the projection light L as image light P at a constant rate throughout the entire area of ​​the output region 230. In this case, the amount of projection light L decreases as the projection light L travels away from the intermediate region 220, and therefore the intensity of the image light P output from the output region 230 may vary depending on the distance from the input region 210 and the distance from the output region 230. For example, the brightness may gradually decrease from the upper left pixel to the lower right pixel of the image projected by the output region 230. The projection substrate 100 according to this embodiment reduces such variations in brightness.

[0037] <Example of Projection Light and Image Light> FIG. 4 shows an example of the projection light L irradiated onto the projection substrate 100 by the projection unit 120 according to this embodiment and the image light P emitted from the projection substrate 100. The projection unit 120 irradiates the projection light L, for example, toward the second surface of the projection substrate 100 located in the +Z direction. The projection light L corresponds to an image to be shown to the user. For example, when the projection light L is projected onto a screen or the like placed on a surface substantially parallel to the XY plane, an image M1 is displayed on the screen for the user to observe. The image to be shown to the user is, for example, an augmented reality (AR) image or a virtual reality (VR) image created by a processor included in the projection unit 120. In this way, the projection unit 120 irradiates, as the projection light L, a plurality of light rays that form the image M1 on a surface substantially parallel to the XY plane.

[0038] In this embodiment, an example will be described in which the projection unit 120 projects a substantially rectangular image M1 with the X-axis direction as the longitudinal direction on a plane substantially parallel to the XY plane. Also, in Fig. 4, five of the multiple light rays emitted by the projection unit 120 are shown as input light rays 20. For example, the light ray corresponding to the upper left pixel of the image is the first input light ray 20a, the light ray corresponding to the lower left pixel of the image is the second input light ray 20b, the light ray corresponding to the central pixel of the image is the third input light ray 20c, the light ray corresponding to the upper right pixel of the image is the fourth input light ray 20d, and the light ray corresponding to the lower right pixel of the image is the fifth input light ray 20e.

[0039] The projection unit 120, for example, irradiates the projection light L onto the entrance region 210 of the projection substrate 100 so as to create an erect virtual image at infinity or at a predetermined position. The projection light incident on the entrance region 210 passes through the intermediate region 220 and is emitted from the exit region 230 as image light P. The image light P is emitted from the exit region 230 and enters the user's eye, which is a distance d away from the projection substrate 100. The image light P is then focused as image M2 on the retina of the user's eye. In this way, the image light P includes a plurality of light beams that are focused as image M2.

[0040] 4, five of the multiple ray bundles that are emitted from the circular region C of the emission region 230 of the projection substrate 100 and form an image at a predetermined position are shown as output ray bundles 30. For example, the ray bundle that forms an image as the lower right pixel of the image is designated as the first output ray bundle 30a, the ray bundle that forms an image as the upper right pixel of the image is designated as the second output ray bundle 30b, the ray bundle that forms an image as the central pixel of the image is designated as the third output ray bundle 30c, the ray bundle that forms an image as the lower left pixel of the image is designated as the fourth output ray bundle 30d, and the ray bundle that forms an image as the upper left pixel of the image is designated as the fifth output ray bundle 30e.

[0041] Each ray bundle corresponds to one of the multiple input light rays 20 incident from the projection unit 120. For example, the first output ray bundle 30a corresponds to the first input light ray 20a, and includes multiple light rays generated by multiple branching and multiple diffractions of the first input light ray 20a as it travels from the incident region 210 to the exit region 230 of the projection substrate 100. Similarly, the second output ray bundle 30b corresponds to the second input light ray 20b, the third output ray bundle 30c corresponds to the third input light ray 20c, the fourth output ray bundle 30d corresponds to the fourth input light ray 20d, and the fifth output ray bundle 30e corresponds to the fifth input light ray 20e.

[0042] In other words, the image M2 formed on the retina of the user's eye by the image light P emitted from the emission region 230 corresponds to the image M1 projected by the projection light L emitted by the projection unit 120. This allows the user wearing the eyeglass-type terminal 10 to feel as if the image M2 is being projected onto the second surface of the projection substrate 100, superimposed on the scenery seen through the projection substrate 100. In other words, the emission region 230 functions as a display region that displays the image M2 corresponding to the image M1 projected by the projection light L.

[0043] 4 shows an example in which the image M2 observed by the user is an image obtained by vertically and horizontally inverting the image M1 projected by the projection light L. The image M1 projected by the projection light L may be a still image, or alternatively, may be a moving image. Next, the projection substrate 100 that emits the image light P corresponding to the incident projection light L as described above will be described.

[0044] <Configuration Example of Projection Substrate 100> Fig. 5 shows a configuration example of the projection substrate 100 according to this embodiment. Fig. 3 shows an example in which the first surface and the second surface of the projection substrate 100 are arranged substantially parallel to the XY plane. The projection substrate 100 is a substrate having an optical waveguide 200 that transmits at least a portion of light incident from the first surface to the second surface opposite the first surface, and projects image light onto the second surface. The projection substrate 100 is, for example, a glass substrate. The projection substrate 100 includes an optical waveguide 200 having an incident region 210, an intermediate region 220, and an exit region 230.

[0045] <Example of Incident Region 210> The incident region 210 receives projection light for projecting image light and guides the incident projection light toward the intermediate region 220. Fig. 5 shows an example in which the incident region 210 has a circular shape on a plane substantially parallel to the XY plane, but is not limited to this. The incident region 210 may have any shape, such as an ellipse, a polygon, or a trapezoid, as long as it can guide the projection light toward the intermediate region 220.

[0046] The incident region 210 has an incident diffraction grating in which a plurality of first grooves 212 are formed at a first period. In other words, the plurality of first grooves 212 are arranged in the same direction on the upper surface of the projection substrate 100 with a predetermined groove width and interval, thereby functioning as a diffraction grating. The incident region 210 has a reflective or transmissive incident diffraction grating and guides projection light toward the intermediate region 220 by reflective diffraction or transmissive diffraction. The first period of the plurality of first grooves 212 is, for example, in the range of approximately 10 nm to 10 μm.

[0047] The multiple first grooves 212 are arranged, for example, in a direction from the incident region 210 toward the intermediate region 220. Here, the traveling direction of the projection light from the incident region 210 toward the intermediate region 220 is defined as the first direction. Figure 5 shows an example in which the first direction is a direction substantially parallel to the X-axis direction, and the first grooves 212 extending in a direction substantially parallel to the Y-axis direction are arranged in the first direction. Since the projection light is incident on the incident region 210 while converging, the incident region 210 guides the projection light to the intermediate region 220 so that the projection light has a divergence angle centered on the first direction within the plane of the projection substrate 100.

[0048] <Example of intermediate region 220> The intermediate region 220 guides a portion of the projection light incident from the entrance region 210 toward the exit region 230. The intermediate region 220 is provided in a region through which the projection light passes, on a plane substantially parallel to the XY plane. The intermediate region 220 has a reflective intermediate diffraction grating, and guides the projection light toward the exit region 230 by reflective diffraction. The intermediate region 220 has, for example, a rectangular shape with the first direction as its longitudinal direction.

[0049] Since the projection light propagates while spreading around the first direction, it is preferable that the intermediate region 220 has a shape that spreads away from the first direction, which is the propagation direction of the projection light passing through the incident region 210, as it moves away from the incident region 210. The intermediate region 220 has, for example, a trapezoidal, fan-shaped, or other shape on a plane substantially parallel to the XY plane. Figure 5 shows an example in which the intermediate region 220 has a trapezoidal shape. An intermediate region 220 of this shape can be formed corresponding to the region where the projection light propagates while spreading in the XY plane, and can efficiently guide the projection light.

[0050] The intermediate region 220 has an intermediate diffraction grating in which a plurality of second grooves 222 are formed at a second period. In other words, the plurality of second grooves 222 are arranged in the same direction on the upper surface of the projection substrate 100 with a predetermined groove width and interval, thereby functioning as a diffraction grating. The intermediate region 220 functions as, for example, a reflective intermediate diffraction grating and guides the projection light to the output region 230.

[0051] The second period of the plurality of second groove portions 222 is different from the first period of the plurality of first groove portions 212. It is desirable to select an appropriate second period for guiding the projection light to the emission region 230. The second period is, for example, in the range of about 10 nm to about 10 μm.

[0052] The plurality of second grooves 222 are arranged, for example, in a predetermined direction. For example, the direction from the intermediate region 220 toward the emission region 230 is defined as the second direction, and the angle between the first direction and the second direction is defined as the first angle. In this case, the plurality of second grooves 222 are formed in a direction inclined toward the second direction by an angle that is half the first angle with respect to the first direction. Figure 5 shows an example in which the second direction is substantially parallel to the Y-axis direction, the first angle is substantially 90 degrees, and the plurality of second grooves 222 are arranged in a direction inclined toward the second direction by substantially 45 degrees with respect to the first direction.

[0053] The intermediate region 220 has a plurality of first divided regions 224 arranged in the traveling direction of the incident projection light. The second grooves 222 formed in the plurality of first divided regions 224 have different depths. In other words, the second grooves 222 are formed in the intermediate region 220 so that the proportion of the incident projection light that is guided to the emission region 230 differs for each first divided region 224.

[0054] It is desirable that the intermediate region 220 have three or more first divided regions 224. In this way, the intermediate region 220 is divided into a plurality of first divided regions 224, and the amount of projection light guided to the emission region 230 is varied for each first divided region 224, thereby guiding projection light whose intensity varies depending on the distance from the incidence region 210 to the emission region 230, while adjusting the distribution of the light amount in the direction perpendicular to the traveling direction of the projection light to be approximately constant.

[0055] For example, the second grooves 222 are formed so that the depth of the second grooves 222 provided in one first divided region 224 is greater than the depth of the second grooves 222 provided in a first divided region 224 that is closer to the incident region 210 than the one first divided region 224. In this case, the rate of change in the depth of the second grooves 222 between two adjacent first divided regions 224 among the plurality of first divided regions 224 may be greater the farther away from the incident region 210.

[0056] 5, consider an intermediate region 220 having three first divided regions 224. Here, the first divided region 224a, which is closest to the incident region 210 among the three first divided regions 224, has a depth of the second groove 222a formed so that approximately one-quarter of the amount of incident projection light is guided to the output region 230. In this case, the remaining approximately three-quarters of the amount of projection light that is incident on the first divided region 224a closest to the incident region 210 is incident on the adjacent first divided region 224b.

[0057] The depth of the second groove 222b of the first divided region 224b second closest to the entrance region 210 is formed so that the second groove 222b guides approximately one-third of the amount of incident projection light to the exit region 230. In other words, the depth of the second groove 222b of the first divided region 224b second closest to the entrance region 210 is formed greater than the depth of the second groove 222a so that the first divided region 224b guides 4 / 3 times the amount of light to the exit region 230 compared to the first divided region 224a closest to the entrance region 210. This first divided region 224b guides approximately one-quarter of the amount of projection light incident on the first divided region 224a closest to the entrance region 210 to the exit region 230.

[0058] The remaining approximately half of the amount of projection light that is incident on the first divided region 224a that is closest to the incident region 210 is incident on the adjacent first divided region 224c. The first divided region 224c that is third closest to the incident region 210 has a depth of the second groove 222c formed so as to guide approximately half of the amount of incident projection light to the output region 230. In other words, the depth of the second groove 222c of the first divided region 224c that is third closest to the incident region 210 is formed greater than the depth of the second groove 222b so as to guide 3 / 2 times the amount of light to the output region 230 compared to the first divided region 224b that is second closest to the incident region 210.

[0059] Furthermore, the rate of change in the depth of the second groove portions 222 of two adjacent first divided regions 224 out of the three first divided regions 224 is formed so that the rate of change increases the further away from the incident region 210. The first divided region 224c, which is third closest to the incident region 210, guides to the output region 230 approximately one-fourth the amount of projection light that was incident on the first divided region 224a, which is closest to the incident region 210. As in the above example, by varying the amount of projection light that the intermediate region 220 guides to the output region 230 to a predetermined value for each first divided region 224, it can be seen that the amount of projection light that the intermediate region 220 guides to the output region 230 corresponding to each first divided region 224 has an approximately constant distribution.

[0060] The intermediate region 220 may further include a first reflective region 226 at a position farthest from the incident region 210. Fig. 5 shows an example in which the intermediate region 220 includes three first divided regions 224 and a first reflective region 226. The first reflective region 226 reflects at least a portion of the light that has passed through the plurality of first divided regions 224 back toward the plurality of first divided regions 224. The first reflective region 226 includes second grooves 222 that are deeper than the depths of the second grooves 222 of the adjacent first divided regions 224.

[0061] Since the intermediate region 220 has such a first reflective region 226, the multiple first divided regions 224 guide at least a portion of the light reflected by the first reflective region 226 to the emission region 230. This allows the intermediate region 220 to guide more projection light to the emission region 230. Note that the depth of the second groove portions 222 of the multiple first divided regions 224 may be determined so that the amount of projection light that each first divided region 224 guides to the emission region 230, including the light reflected by the first reflective region 226, is approximately constant.

[0062] <Example of Exit Region 230> The exit region 230 guides at least a portion of the projection light incident from the intermediate region 220 and emits it as image light from the second surface of the projection substrate 100. Fig. 5 shows an example in which the exit region 230 has a rectangular shape with the X-axis direction as the longitudinal direction on a plane approximately parallel to the XY plane, but is not limited to this. The exit region 230 only needs to be able to guide the projection light and emit it as image light, and may have a shape such as a rectangle, square, or trapezoid with the Y-axis direction as the longitudinal direction.

[0063] The emission region 230 has an emission diffraction grating in which a plurality of third groove portions 232 are formed at a third period. In other words, the plurality of third groove portions 232 are arranged in the same direction on the upper surface of the projection substrate 100 with a predetermined groove width and interval, thereby functioning as a diffraction grating. The emission region 230 has a reflective or transmissive emission diffraction grating and guides image light toward the user's eyes by reflective diffraction or transmissive diffraction.

[0064] The third period of the plurality of third groove portions 232 provided in the emission region 230 is different from the second period of the plurality of second groove portions 222 in the intermediate region 220. The third period of the plurality of third groove portions 232 in the emission region 230 may be the same as the first period of the plurality of first groove portions 212 in the incidence region 210. In this way, by substantially matching the periods of the diffraction gratings provided in the region where the projection light enters and the region where the image light exits, distortions and the like that occur in the image observed by the user can be reduced. The third period is, for example, in the range of approximately 10 nm to 10 μm.

[0065] The plurality of third groove portions 232 are arranged, for example, in a second direction from the intermediate region 220 toward the emission region 230. Fig. 5 shows an example in which the third groove portions 232 extending in the first direction are arranged in the second direction.

[0066] Like the intermediate region 220, the emission region 230 has a plurality of second divided regions 234 arranged in the traveling direction of the projection light incident from the intermediate region 220. The third groove portions 232 formed in the plurality of second divided regions 234 have different depths. In other words, the third groove portions 232 are formed in the emission region 230 so that the proportion of light that is emitted as image light out of the input projection light differs for each second divided region 234.

[0067] It is desirable that the emission region 230 has two or more second divided regions 234. For example, the depth of the third groove portion 232 provided in one second divided region 234 is formed to be greater than the depth of the third groove portion 232 provided in a second divided region 234 that is closer to the intermediate region 220 than the one second divided region 234. Furthermore, when the emission region 230 has three or more second divided regions 234, the rate of change in the depth of the third groove portion 232 of two adjacent second divided regions 234 may be greater the farther away from the intermediate region 220.

[0068] As described above, the emission region 230 is divided into a plurality of second divided regions 234, and the amount of light emitted as image light is made different for each second divided region 234. As a result, like the plurality of first divided regions 224 of the intermediate region 220, the emission region 230 can guide the projection light as image light, while adjusting the distribution of the amount of light across the entire image to be approximately constant when the observer observes the image light as an image.

[0069] The emission region 230 may further include a second reflective region 236 at a position farthest from the intermediate region 220. Fig. 5 shows an example in which the emission region 230 includes two second divided regions 234 and a second reflective region 236. The second reflective region 236 reflects at least a portion of the light that has passed through the plurality of second divided regions 234 back toward the plurality of second divided regions 234. The second reflective region 236 includes a third groove 232 that is deeper than the depth of the third groove 232 of an adjacent second divided region 234.

[0070] Since the emission region 230 has such a second reflection region 236, the plurality of second divided regions 234 emit at least a portion of the light reflected by the second reflection region 236 as image light from the second surface of the projection substrate 100. This allows the emission region 230 to emit a larger amount of projection light as image light, similar to the intermediate region 220. Note that the depth of the third groove portions 232 of the plurality of second divided regions 234 may be determined so that the amount of light emitted as image light by each second divided region 234, including the light reflected by the second reflection region 236, is approximately constant.

[0071] As described above, the projection substrate 100 according to this embodiment branches the projection light incident on the entrance region 210 into different projection light beams for each of the plurality of first divided regions 224 of the intermediate region 220, and then emits the branched projection light as image light from the exit region 230. This allows the projection substrate 100 to reduce variations in the brightness of the projected image observed by the user. Furthermore, the projection substrate 100 also emits image light beams from the exit region 230 at different rates for each of the plurality of second divided regions 234, thereby further reducing variations in the brightness of the image.

[0072] Such a projection substrate 100 can be realized by forming a diffraction grating corresponding to the incident region 210, the intermediate region 220, and the exit region 230 on the front or back surface of a glass substrate or the like. The grooves forming the diffraction grating are made of, for example, resist, resin, etc. Therefore, the projection substrate 100 according to this embodiment is a substrate that can be easily produced by forming grooves with a predetermined period and depth in each region, without incorporating a complex optical system.

[0073] <Second Configuration Example of Glasses-Type Terminal 10> An example of the glasses-type terminal 10 has been described above in which one projection substrate 100 is provided on the frame 110 for each of the projection optical systems 50 for the right and left eyes, and the corresponding projection units 120 irradiate projection light onto the incident areas 210 of the respective projection substrates 100, but this is not limiting. For example, one projection optical system 50 may be provided with multiple projection substrates 100. Such a glasses-type terminal 10 will now be described.

[0074] 6 shows a second configuration example of the eyeglasses-type terminal 10 according to this embodiment. In the eyeglasses-type terminal 10 of the second configuration example, parts that operate in substantially the same manner as the eyeglasses-type terminal 10 according to this embodiment shown in FIG. 1 are given the same reference numerals, and duplicated explanations are omitted. The appearance of the eyeglasses-type terminal 10 of the second configuration example may be almost the same as the eyeglasses-type terminal 10 shown in FIG. 1.

[0075] A plurality of projection substrates 100 are fixed to the frame 110 of the eyeglasses-type terminal 10 of the second configuration example. In this case, the plurality of projection substrates 100 are fixed to the frame 110 so that the emission regions 230 provided on each of the plurality of projection substrates 100 at least partially overlap in a plan view substantially parallel to the XY plane. Fig. 6 shows an example in which three projection substrates 100R, 100G, and 100B are fixed to the frame 110 of the eyeglasses-type terminal 10, and the emission regions 230R, 230G, and 230B of the three projection substrates 100 overlap in a plan view on the XY plane.

[0076] The projection unit 120 irradiates projection light of different wavelengths onto the incident areas 210 provided on each of the plurality of projection substrates 100. As a result, the exit areas 230 provided on each of the plurality of projection substrates 100 emit image light corresponding to the projection light irradiated from the projection unit 120 onto each of the plurality of incident areas 210 from the second surfaces of the plurality of projection substrates 100 to the eyes of the user.

[0077] A user wearing such eyeglass-type terminal 10 will observe an image in which image light of different wavelengths is superimposed, and therefore can observe an image having a mixed color. Fig. 6 shows an example in which the projection unit 120 irradiates three projection lights corresponding to the three primary colors of RGB, such as red, green, and blue, that form an image onto the incident areas 210 of three projection substrates 100, respectively. Then, the three projection substrates 100 superimpose the three image lights corresponding to the three primary colors of RGB and emit them to the user's eyes. This allows the user to see, for example, two ｎ Here, n is a positive integer such as 4, 8, 16, 24, etc.

[0078] <Third Configuration Example of Glasses-Type Terminal 10> In the glasses-type terminal 10 described above, the optical waveguide unit 200 has a diffraction grating, so when light is incident on the projection substrate 100 from above a user wearing the glasses-type terminal 10 at a predetermined angle, the diffracted light diffracted by the diffraction grating may enter the user's eyes. The predetermined angle is, for example, an angle of 30 degrees or more and 80 degrees or less. The predetermined angle may also be an angle of 45 degrees or more and 80 degrees or less, or an angle of 60 degrees or more and 80 degrees or less.

[0079] For example, sunlight, fluorescent light, etc., can travel from above the user toward the user, and when this diffracted light enters the user's eyes, it can cause discomfort to the user or make it difficult for the user to see ahead. Therefore, it is desirable that the eyeglass-type terminal 10 according to this embodiment be configured to reduce such diffracted light. Such a configuration will be described next.

[0080] Fig. 7 shows a third configuration example of the eyeglasses-type terminal 10 according to this embodiment. In the eyeglasses-type terminal 10 of the third configuration example, parts that operate in substantially the same manner as the eyeglasses-type terminal 10 according to this embodiment shown in Fig. 1 are assigned the same reference numerals, and redundant explanations will be omitted. Note that Fig. 7 is a diagram in which the projection unit 120 is omitted. The appearance of the eyeglasses-type terminal 10 of the third configuration example may be almost the same as that of the eyeglasses-type terminal 10 shown in Fig. 1.

[0081] In the eyeglass-type terminal 10 of the third configuration example, the projection optical system 50 further includes a diffracted light reducing plate 310. The diffracted light reducing plate 310 is provided on the first surface side of the projection substrate 100 with respect to the optical waveguide unit 200 of the projection substrate 100, with an air layer interposed between the diffracted light reducing plate 310 and the optical waveguide unit 200. In this way, the diffracted light reducing plate 310 is provided away from the optical waveguide unit 200 so as not to affect the optical characteristics of the optical waveguide unit 200.

[0082] The diffracted light reduction plate 310 covers at least a portion of the light guide unit 200 and reduces diffracted light that occurs when incident light incident from the first surface of the projection substrate 100 at a predetermined incident angle is diffracted in the light guide unit 200 and travels in the direction from which image light is emitted. Here, the incident angle is the angle between the incident light and the normal to the boundary surface at the point where the incident light intersects with the boundary surface of the medium, and is, for example, the angle indicated by θ in FIG. 7 . The diffracted light reduction plate 310 covers, for example, at least a portion of the output diffraction grating of the output region 230. This allows the diffracted light reduction plate 310 to receive incident light that travels from the first surface side of the projection substrate 100 at a predetermined incident angle and travels toward the diffraction grating of the light guide unit 200.

[0083] Incident light having a predetermined angle of incidence and directed toward the diffraction grating of the optical waveguide unit 200 is diffracted by the diffraction grating. Of the diffracted light diffracted by the diffraction grating, the diffracted light directed toward the image light emitted from the second surface of the projection substrate 100 is directed toward the user's eyes and may enter the user's field of vision.

[0084] It is known that the intensity of diffracted light diffracted by such a diffraction grating varies depending on the polarization direction. For example, the intensity of P-wave diffracted light, which is parallel to the plane of incidence of the incident light, is greater than the intensity of S-wave diffracted light, which is perpendicular to the plane of incidence of the incident light. Therefore, the diffracted light reducing plate 310 is provided to reduce the P-wave of the incident light and transmit the S-wave.

[0085] As a result, the diffracted light reducing plate 310 can reduce the intensity of diffracted light heading toward the eyes of the user even when light is incident from above the user wearing the eyeglasses-type terminal 10. Furthermore, the diffracted light reducing plate 310 transmits S-wave light out of the incident light to the projection board 100, and therefore transmits at least a portion of external light so that it can be seen by the user.

[0086] 7 shows an example in which the diffracted light reducing plate 310 is provided opposite the first surface of the projection substrate 100 and has a polarizing filter that reduces P waves parallel to the plane of incidence of incident light that is incident on the diffracted light reducing plate 310. The polarizing filter is a polarizing plate, polarizing film, or the like that attenuates linearly polarized components of the input light in a predetermined direction. The diffracted light reducing plate 310 is desirably fixed to the frame 110 or the projection substrate 100. Note that the diffracted light reducing plate 310 may have a rotatable polarizing filter so that the polarization direction (absorption axis) of the light to be reduced can be adjusted.

[0087] 7 has described an example in which the diffracted light reducing plate 310 reduces the P wave of the incident light that enters the projection substrate 100 in order to reduce the diffracted light diffracted by the optical waveguide unit 200 of the projection substrate 100, but the present invention is not limited to this. For example, the diffracted light reducing plate 310 may reduce the P wave of the diffracted light diffracted by the optical waveguide unit 200 of the projection substrate 100.

[0088] In this case, the diffracted light reducing plate 310 is provided opposite the second surface of the projection substrate 100 and reduces the P wave of the light emitted from the projection substrate 100. In other words, the diffracted light reducing plate 310 is provided between the user and the projection substrate 100. Even with this arrangement of the diffracted light reducing plate 310, the intensity of the diffracted light heading toward the user's eyes can be reduced, similar to the arrangement shown in FIG. 7 . The diffracted light reducing plate 310 may also be a polarizing film coated on a transparent substrate or the like. Such a diffracted light reducing plate 310 will be described next.

[0089] <Fourth Configuration Example of Glasses-Type Terminal 10> Figure 8 shows a fourth configuration example of the glasses-type terminal 10 according to this embodiment. In the glasses-type terminal 10 of the fourth configuration example, parts that operate in substantially the same manner as the glasses-type terminal 10 according to this embodiment shown in Figures 1 and 7 are given the same reference numerals, and duplicated explanations are omitted. The appearance of the glasses-type terminal 10 of the fourth configuration example may be almost the same as the glasses-type terminal 10 shown in Figure 1.

[0090] In the eyeglass-type terminal 10 of the fourth configuration example, the diffracted light reduction plate 310 includes a protective substrate 320 and a polarizing film 330. The protective substrate 320 is provided opposite the first surface of the projection substrate 100. Alternatively, the protective substrate 320 may be provided opposite the second surface of the projection substrate 100. The protective substrate 320 is a substrate that is transparent to at least visible light, such as a glass substrate or a plastic substrate.

[0091] The polarizing film 330 is coated on at least one of a third surface of the protective substrate 320 opposite to the projection substrate 100 and a fourth surface facing the projection substrate 100. Figure 8 shows an example in which the polarizing film 330 is coated on the third surface of the protective substrate 320.

[0092] Similar to a polarizing filter, the polarizing film 330 is a thin film that reduces P waves parallel to the plane of incidence of light incident on the diffracted light reduction plate 310. The polarizing film 330 may be coated on a part or the entirety of the protective substrate 320.

[0093] In this way, the diffracted light reducing plate 310 having the protective substrate 320 and the polarizing film 330 can also reduce the intensity of diffracted light directed toward the user's eyes, similar to the diffracted light reducing plate 310 described in Fig. 7. The protective substrate 320 is desirably fixed to the frame 110 or the projection substrate 100. The protective substrate 320 may also be rotatable, so that the direction of the absorption axis of the diffracted light reducing plate 310 can be adjusted.

[0094] <Fifth Configuration Example of Glasses-Type Terminal 10> Figure 9 shows a fifth configuration example of the glasses-type terminal 10 according to this embodiment. In the glasses-type terminal 10 of the fifth configuration example, components that operate substantially the same as those of the glasses-type terminal 10 of the fourth configuration example shown in Figure 8 are given the same reference numerals, and duplicated explanations will be omitted. The diffracted light reduction plate 310 of the fifth configuration example has a protection substrate 320, a polarizing filter 340, and an infrared cut filter 350.

[0095] The polarizing filter 340 is provided on the third surface of the protective substrate 320 opposite the projection substrate 100, and reduces P waves parallel to the plane of incidence of the incident light that is incident on the diffracted light reduction plate 310. The polarizing filter 340 is a polarizing plate, polarizing film, or the like. The polarizing filter 340 may also be the polarizing film described in FIG. 8. Such a polarizing filter 340 has the effect of reducing the intensity of diffracted light heading toward the user's eyes, as described in FIGS. 7 and 8.

[0096] The infrared cut filter 350 is provided on the fourth surface of the protection substrate 320 facing the projection substrate 100, and reduces light in the infrared region of the incident light. The infrared cut filter 350 is, for example, an IR cut filter that reduces near-infrared light using a multilayer film.

[0097] Such an infrared cut filter 350 reduces light in the infrared range of incident light when the angle of incidence of the incident light onto the filter is approximately 0 degrees. Furthermore, the infrared cut filter 350 also reduces light in the visible range when the angle of incidence of the incident light becomes large, for example, 50 degrees or greater. Therefore, the infrared cut filter 350 can reduce incident light in the visible range that is incident on the projection board 100 from above the user at a predetermined angle. Therefore, the eyeglass-type terminal 10 of the fifth configuration example can further reduce the intensity of diffracted light heading toward the user's eyes.

[0098] 9 shows an example in which the polarizing filter 340 is provided on the third surface of the protective substrate 320 and the infrared cut filter 350 is provided on the fourth surface of the protective substrate 320, but this is not limiting. The diffracted light reducing plate 310 may also have the infrared cut filter 350 provided on the third surface of the protective substrate 320 and the polarizing filter 340 provided on the fourth surface of the protective substrate 320.

[0099] <Sixth Configuration Example of Glasses-Type Terminal 10> In the glasses-type terminal 10 according to the present embodiment, an example in which diffracted light diffracted by the optical waveguide unit 200 of the projection substrate 100 is reduced has been described above, but the present invention is not limited to this. The glasses-type terminal 10 may be further configured to reduce image light leaking from the first surface of the projection substrate 100.

[0100] In the eyeglass-type terminal 10, a portion of the image light that should be emitted toward the user may end up emitting as leaked light in a direction different from the user. For example, a portion of the image light that is emitted from the second surface of the projection board 100 may end up emitting from the first surface of the projection board 100 due to the diffraction grating of the optical waveguide unit 200. In this case, a person looking at the user may find the user's eyes to appear to be glowing, which may be unpleasant.

[0101] The image light leaking from the output diffraction grating is light that has been guided through the multiple diffraction gratings of the optical waveguide 200, and therefore becomes light that is polarized in one direction in accordance with the structure of the optical waveguide 200. Therefore, the intensity of the leaked image light can be reduced by providing a diffracted light reduction plate 310 opposite the first surface of the projection substrate 100 and roughly matching the polarization direction of the image light with the polarization direction (absorption axis) of the light reduced by the diffracted light reduction plate 310. Such an eyeglass-type terminal 10 will now be described.

[0102] Fig. 10 shows a sixth configuration example of the eyeglasses-type terminal 10 according to this embodiment. In the eyeglasses-type terminal 10 of the sixth configuration example, parts that operate in substantially the same manner as the eyeglasses-type terminal 10 of the third configuration example shown in Fig. 7 are assigned the same reference numerals, and redundant explanations will be omitted. The eyeglasses-type terminal 10 of the sixth configuration example is configured so that the polarization direction of image light can be adjusted.

[0103] The projection unit 120 has a polarization adjuster 122 that adjusts the polarization direction of the projection light that is irradiated onto the incident region of the optical waveguide unit 200. The polarization adjuster 122 has, for example, a wavelength plate that rotates the polarization direction of linearly polarized light. The polarization adjuster 122 adjusts the polarization direction of the projection light so that the polarization direction of the image light and the polarization direction of the light reduced by the diffracted light reduction plate 310 approximately coincide with each other. The polarization adjuster 122 adjusts the polarization direction of the projection light so that the polarization direction of the image light becomes a P wave with respect to the diffracted light reduction plate 310, for example.

[0104] As a result, the diffracted light reducing plate 310 can reduce leakage of image light emitted from the first surface of the projection substrate 100. In other words, the diffracted light reducing plate 310 can reduce the intensity of the leaked image light to an extent that the image light is not noticeable to others when looking at the user wearing the eyeglass-type terminal 10, while reducing the diffracted light heading toward the user's eyes. Furthermore, the diffracted light reducing plate 310 transmits light polarized in a direction perpendicular to the polarization direction of the leaked image light, and therefore can transmit at least a portion of external light so that it can be seen by the user.

[0105] <Seventh Configuration Example of Glasses-Type Terminal 10> In the glasses-type terminal 10 according to the present embodiment described above, the diffracted light reducing plate 310 has a polarizing filter or the like that reduces light in a predetermined polarization direction, and an example has been described in which the diffracted light diffracted by the optical waveguide unit 200 of the projection board 100 is reduced, but this is not limiting. The diffracted light reducing plate 310 may have, for example, a light control filter that changes the amount of light that diffuses incident light depending on the angle of incidence of the incident light.

[0106] 11 shows a seventh configuration example of the eyeglasses-type terminal 10 according to this embodiment. In the eyeglasses-type terminal 10 of the seventh configuration example, parts that operate in substantially the same manner as the eyeglasses-type terminal 10 of the fourth configuration example shown in FIG. 8 are given the same reference numerals, and redundant explanations will be omitted. The diffracted light reduction plate 310 of the seventh configuration example has a protection substrate 320 and a light control filter 410.

[0107] The light control filter 410 is provided on at least one of a third surface of the protective substrate 320 opposite to the projection substrate 100 and a fourth surface facing the projection substrate 100. The light control filter 410 passes incident light that has entered the diffracted light reduction plate 310 at an incident angle within a first angle range to the optical waveguide unit 200.

[0108] The first angle range includes angles near 0°. For example, the first angle range may be a range from +30° to −30°, or alternatively, a range from +20° to −20°. The first angle range may be a range from +10° to −10°. Furthermore, the first angle range may include a large range of incident angles having a different sign from the predetermined incident angle of incident light at which the optical waveguide 200 generates diffracted light. For example, if the sign of the predetermined incident angle is +, the first angle range is a range from +20° to −70°. Alternatively, the first angle range may be a range from +10° to −60°.

[0109] The light control filter 410, for example, passes incident light with an incident angle of around 0° to the optical waveguide unit 200. As a result, when the eyeglass-type terminal 10 is worn by a user, the user can see light in the outside world.

[0110] Furthermore, when light is incident on the diffracted light reduction plate 310 at an incident angle in a second angle range different from the first angle range, the light control filter 410 diffuses the incident light and attenuates the amount of light that travels straight and reaches the optical waveguide unit 200 more than when the incident light is incident at an incident angle in the first angle range. The second angle range of the incident light on the light control filter 410 is a range of angles larger than the angles in the first angle range.

[0111] Light control filter 410 diffuses incident light having an incident angle of, for example, +30° to +80° to attenuate the amount of light passing through to optical waveguide unit 200. Light control filter 410 may diffuse incident light having an incident angle of +45° to +80°, or may diffuse incident light having an incident angle of +60° to +80°.

[0112] The second angle range of the incident light on the light control filter 410 includes a predetermined incident angle of the incident light at which the light guide unit 200 generates diffracted light due to the incident light that is incident from the first surface of the projection substrate 100. As a result, even if incident light having a predetermined incident angle is incident on the diffracted light reduction plate 310, the light control filter 410 reduces the incident light that reaches the light guide unit 200 while maintaining a direction that is substantially the same as the incident direction of the incident light, and therefore it is possible to reduce the intensity of the diffracted light that is diffracted by the light guide unit 200 and heads toward the user's eye.

[0113] Such a light control filter 410 may be attached to the protective substrate 320, or alternatively, may be formed by depositing a filter material on at least one of the third and fourth surfaces of the protective substrate 320. An example of the actual optical characteristics of such a light control filter 410 is shown in FIG.

[0114] Fig. 12 shows an example of the transmittance characteristics of the light control filter 410 according to this embodiment. In Fig. 12, the horizontal axis represents the angle of incidence of light incident on the light control filter 410, and the vertical axis represents the transmittance. Here, the transmittance is the transmittance of light emitted in a direction substantially identical to the direction of incidence of the light, and is sometimes referred to as linear transmittance. The linear transmittance is, for example, a value obtained by multiplying by 100 the ratio of the amount of light detected by the photodetector via the light control filter 410 to the amount of light detected by the photodetector without passing through the light control filter 410, for the same incident light. The value of such linear transmittance decreases as the amount of diffused light in the incident light increases.

[0115] A in Fig. 12 is light control filter 410 designed to further diffuse and reduce incident light at an incident angle of +30°. Similarly, B in Fig. 12 is light control filter 410 designed to further diffuse and reduce incident light at an incident angle of +45°, and C is light control filter 410 designed to further diffuse and reduce incident light at an incident angle of +60°.

[0116] It can be seen that any of the light control filters 410 A to C can reduce incident light incident at a predetermined incident angle while transmitting 50% or more of incident light with an incident angle of about 0°. Such light control filters 410 are known as anisotropic optical films, as described in Patent Document 2, and therefore a detailed description of the configuration will be omitted here.

[0117] 11 , the diffracted light reduction plate 310 of the eyeglass-type terminal 10 may have the light control filter 410 facing one surface of the protective substrate 320, or may be provided on both surfaces. Alternatively, the light control filter 410 may be provided on one surface of the protective substrate 320, and the polarizing filter 340 may be provided on the other surface. Alternatively, the light control filter 410 may be provided on one surface of the protective substrate 320, and the infrared cut filter 350 may be provided on the other surface. Even with these configurations, the diffracted light reduction plate 310 can reduce the intensity of diffracted light that is diffracted by the optical waveguide unit 200 and heads toward the user's eye.

[0118] <Other Configuration Examples of the Glasses-Type Terminal 10> In the glasses-type terminal 10 according to the present embodiment described above, an example has been described in which the diffracted light reducing plate 310 is provided opposite the second surface of the projection substrate 100. In this case, the diffracted light reducing plate 310 is provided between the projection substrate 100 and the user, and the diffracted light reducing plate 310 is configured to reduce diffracted light while transmitting image light emitted from the projection substrate 100 toward the user.

[0119] Even in this case, the eyeglass-type terminal 10 may be configured to be able to adjust the polarization direction of the image light. For example, as described above, the projection unit 120 has a polarization adjustment unit 122 that adjusts the polarization direction of the projection light that is irradiated onto the incident region of the optical waveguide unit 200. The polarization adjustment unit 122 adjusts the polarization direction of the projection light so that the polarization direction of the image light and the polarization direction of the light transmitted by the diffracted light reduction plate 310 approximately coincide with each other. As an example, the polarization adjustment unit 122 adjusts the polarization direction of the projection light so that the polarization direction of the image light becomes an S-wave with respect to the diffracted light reduction plate 310.

[0120] As a result, even when the diffracted light reducing plate 310 is provided between the projection substrate 100 and the user, it can reduce the diffracted light directed toward the user's eyes while transmitting the image light emitted from the projection substrate 100 toward the user, allowing the user to view it. Note that even if the polarization direction of the projection light is not adjusted, if the polarization direction of the image light projected from the projection substrate 100 toward the user is approximately perpendicular to the absorption axis of the diffracted light reducing plate 310, such a polarization adjuster 122 may not be necessary.

[0121] 6, the above eyeglass-type terminal 10 may have a projection optical system 50 including a plurality of projection substrates 100, and allow the user to view an image in which a plurality of image lights of different wavelengths are superimposed. In this case, it is desirable that the polarization directions of the plurality of image lights are approximately the same.

[0122] The diffracted light reducing plate 310 is provided on the side of the multiple projection substrates 100 opposite the user, or between the multiple projection substrates 100 and the user. Fig. 6 shows an example in which the projection optical system 50 has three projection substrates 100 and one diffracted light reducing plate 310 provided on the side of the three projection substrates 100 opposite the user.

[0123] Furthermore, when the projection optical system 50 has a plurality of projection substrates 100, the diffracted light reducing plate 310 may be provided between two different projection substrates 100. Even with such an arrangement, the diffracted light reducing plate 310 can reduce diffracted light directed toward the user's eyes. In other words, the diffracted light reducing plate 310 is provided on the side of one of the plurality of projection substrates 100 opposite the user, or between one projection substrate 100 and the user. Furthermore, the projection optical system 50 may have a plurality of such diffracted light reducing plates 310.

[0124] Note that even when the projection optical system 50 has multiple projection substrates 100, the eyeglass-type terminal 10 may be configured to be able to adjust the polarization direction of the image light. For example, the projection unit 120 has a polarization adjuster 122 that adjusts the polarization direction of at least one of the multiple projection lights irradiated onto the incident area. The projection unit 120 may also have a polarization adjuster 122 that adjusts the polarization direction of all of the projection lights.

[0125] The diffracted light reducing plate 310 may be provided on the side of the multiple projection substrates 100 opposite the user. In this case, the polarization adjuster 122 adjusts the polarization direction of the projection light so that the polarization direction of at least one of the multiple image lights substantially coincides with the polarization direction of the light reduced by the diffracted light reducing plate 310. In this way, the diffracted light reducing plate 310 can reduce the intensity of the image light leaking from the first surface of at least one projection substrate 100 while reducing the diffracted light directed toward the user's eyes.

[0126] The projection unit 120 may have a plurality of polarization adjusters 122 that adjust the polarization directions of the plurality of projection lights corresponding to the plurality of projection lights irradiated onto the incident area 210. In this case, the projection unit 120 can adjust the polarization directions of the plurality of projection lights so that the diffracted light reducing plate 310 appropriately reduces leakage light corresponding to the plurality of projection lights while efficiently guiding the plurality of projection lights in the optical waveguide unit 200.

[0127] Alternatively, the diffracted light reducing plate 310 may be provided between the user and one of the multiple projection substrates 100. In this case, the polarization adjusting unit 122 adjusts the polarization direction of the projection light so that the polarization direction of the image light emitted by one of the multiple image light projection substrates 100 substantially coincides with the polarization direction of the light transmitted by the diffracted light reducing plate 310.

[0128] As a result, the diffracted light reduction plate 310 reduces the diffracted light directed toward the user's eyes, while transmitting the image light emitted toward the user from the second surface of the projection substrate 100, allowing the user to view it. Even in this case, it goes without saying that the projection unit 120 may have a plurality of polarization adjustment units 122 that adjust the polarization directions of the plurality of projection light beams corresponding to the plurality of projection light beams irradiated onto the incident area 210.

[0129] In the eyeglasses-type terminal 10 according to the present embodiment, an example has been described in which the diffracted light reducing plate 310 is provided so as to cover at least a portion of the optical waveguide unit 200. The diffracted light reducing plate 310 need not cover the entire optical waveguide unit 200, as long as it is able to reduce the diffracted light directed toward the user's eyes. In this case, the diffracted light reducing plate 310 may be provided in a range above the lower end of the optical waveguide unit 200 when the eyeglasses-type terminal 10 including the projection optical system 50 is worn so as to cover the user's eyes.

[0130] Alternatively or additionally, the diffracted light reduction plate 310 does not need to cover the upper end of the light guide unit 200 if diffracted light generated at the upper end of the light guide unit 200 is directed above the user's eyes. The diffracted light reduction plate 310 is provided so as to expose, for example, 1% to 20% or 1% to 30% of the area of ​​the light guide unit 200. Alternatively, the diffracted light reduction plate 310 may be provided so as to expose 1% to 40% of the area of ​​the light guide unit 200. In this way, by forming the diffracted light reduction plate 310 on the protective substrate 320 with an area smaller than that of the light guide unit 200, it is possible to improve visibility for the user and reduce manufacturing costs.

[0131] Furthermore, when diffracted light generated at the upper end of the optical waveguide 200 is directed toward the user's eyes, the diffracted light reducing plate 310 may be formed to cover an area of ​​the projection substrate 100 where the optical waveguide 200 is not formed. For example, the diffracted light reducing plate 310 may be provided in a range that includes a position above the optical waveguide 200 when the eyeglass-type terminal 10 including the projection optical system 50 is worn so as to cover the user's eyes. This allows the diffracted light reducing plate 310 to reduce diffracted light directed toward the user's eyes.

[0132] In the eyeglass-type terminal 10 according to the present embodiment, an example has been described in which the optical waveguide unit 200 of the projection substrate 100 has the incident region 210, the intermediate region 220, and the exit region 230, but the present invention is not limited to this. The optical waveguide unit 200 only needs to output the projection light incident from the projection unit 120 as image light for the user to observe, and the shapes of the incident region 210, the intermediate region 220, and the exit region 230 may be other shapes. Furthermore, the optical waveguide unit 200 may have, for example, the incident region 210 and the exit region 230, but not the intermediate region 220.

[0133] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating in any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments.

[0134] REFERENCE SIGNS LIST 10 Glasses-type terminal 20 Input light beam 30 Output light beam bundle 50 Projection optical system 100 Projection substrate 110 Frame 120 Projection unit 122 Polarization adjustment unit 200 Light guide unit 210 Incident area 212 First groove portion 220 Intermediate area 222 Second groove portion 224 First division area 226 First reflection area 230 Exit area 232 Third groove portion 234 Second division area 236 Second reflection area 310 Diffracted light reduction plate 320 Protective substrate 330 Polarizing film 340 Polarizing filter 350 Infrared cut filter 410 Light control filter

Claims

1. a projection substrate having an optical waveguide, the projection substrate transmitting at least a portion of light incident from a first surface to a second surface opposite the first surface, and projecting image light onto the second surface; a diffracted light reduction plate that is provided with respect to the light guide unit on the side of the first surface or the second surface of the projection board via an air layer, covers at least a part of the light guide unit, and reduces diffracted light that is incident on the first surface of the projection board at a predetermined incident angle and is diffracted by the light guide unit and travels in the direction in which the image light is emitted; Equipped with the optical waveguide portion guides at least a portion of the projection light for projecting the image light and emits the projection light from the second surface as the image light; The diffracted light reduction plate is a protection substrate provided opposite the first surface or the second surface of the projection substrate; a polarization filter provided on one of a third surface of the protection substrate opposite to the projection substrate and a fourth surface facing the projection substrate, the polarization filter reducing P waves parallel to the plane of incidence of the incident light that is incident on the diffracted light reducing plate; an infrared cut filter that is provided on a surface of the protection substrate opposite to a surface on which the polarizing filter is provided, and that reduces light in the infrared region of the incident light; having Projection optical system.

2. a projection substrate having an optical waveguide, the projection substrate transmitting at least a portion of light incident from a first surface to a second surface opposite the first surface, and projecting image light onto the second surface; a diffracted light reduction plate that is provided with respect to the light guide unit on the side of the first surface or the second surface of the projection board via an air layer, covers at least a part of the light guide unit, and reduces diffracted light that is incident on the first surface of the projection board at a predetermined incident angle and is diffracted by the light guide unit and travels in the direction in which the image light is emitted; Equipped with the optical waveguide portion guides at least a portion of the projection light for projecting the image light and emits the projection light from the second surface as the image light; The diffracted light reduction plate is a protection substrate provided opposite the first surface or the second surface of the projection substrate; a light control filter that is provided on at least one of a third surface of the protection substrate opposite to the projection substrate and a fourth surface facing the projection substrate, and that passes the incident light that is incident on the diffracted light reducing plate at an incident angle within a first angle range to the light guide unit, and diffuses the incident light that is incident on the diffracted light reducing plate at an incident angle within a second angle range that is different from the first angle range, thereby attenuating the amount of light that travels straight and reaches the light guide unit compared to when the incident light is incident at an incident angle within the first angle range; having Projection optical system.

3. the light control filter is formed by depositing a filter material on at least one of the third surface and the fourth surface of the protection substrate, 3. The projection optical system according to claim 2.

4. 3. The projection optical system according to claim 2, wherein the second angle range of the light control filter includes the predetermined angle of incidence of the incident light at which the optical waveguide generates the diffracted light due to the incident light incident from the first surface of the projection substrate.

5. a projection substrate having an optical waveguide, the projection substrate transmitting at least a portion of light incident from a first surface to a second surface opposite the first surface, and projecting image light onto the second surface; a diffracted light reduction plate that is provided on the second surface side of the projection board with an air layer interposed between the light guide unit and the projection board, covers at least a part of the light guide unit, and reduces diffracted light that is incident on the first surface of the projection board at a predetermined incident angle and is diffracted by the light guide unit and travels in the direction in which the image light is emitted; Equipped with the optical waveguide portion guides at least a part of the projection light for projecting the image light and outputs the projection light from the second surface as the image light. Projection optical system.

6. The projection optical system according to claim 5, wherein the diffracted light reduction plate is disposed opposite the second surface of the projection substrate and has a polarizing filter that reduces P waves parallel to the plane of incidence of the incident light that is incident on the diffracted light reduction plate.

7. The diffracted light reduction plate is a protection substrate provided opposite the second surface of the projection substrate; a polarizing film that is coated on at least one of a third surface of the protective substrate opposite to the projection substrate and a fourth surface facing the projection substrate, and that reduces P waves parallel to the plane of incidence of the incident light that is incident on the diffracted light reducing plate; having 6. The projection optical system according to claim 5.

8. the diffracted light reducing plate is provided in a range including a position above the optical waveguide unit when the eyeglass-type terminal including the projection optical system is worn by a user so as to cover the user's eyes.

6. The projection optical system according to claim 5.

9. the diffracted light reducing plate is provided in a range above a lower end of the optical waveguide unit when the eyeglass-type terminal including the projection optical system is worn by a user so as to cover the user's eyes.

9. The projection optical system according to claim 8.

10. The optical waveguide portion is an incident region including an incident diffraction grating, into which projection light for projecting the image light is incident and which guides the incident projection light into the projection substrate; an exit region including an exit diffraction grating, which guides at least a portion of the projection light incident from the entrance region and outputs the light as the image light from the second surface; and the diffracted light reduction plate covers at least a portion of the output diffraction grating; 6. The projection optical system according to claim 5.

11. the optical waveguide unit further includes an intermediate region that includes an intermediate diffraction grating and guides a portion of the projection light incident from the incident region toward the exit region; the incident diffraction grating has a plurality of first groove portions formed at a first period; the intermediate diffraction grating has a plurality of second groove portions formed at a second period; the output diffraction grating has a plurality of third groove portions formed at a third period; The projection optical system according to claim 10.

12. A glasses-type terminal worn by a user, the projection optical system according to claim 1 , which is provided as at least one of a lens for a right eye and a lens for a left eye of the user, and which projects the image light onto the second surface while transmitting at least a part of light incident from the first surface to the eye of the user; a frame that fixes the projection optical system; a projection unit provided on the frame, which irradiates the projection light onto an incident area of ​​the optical waveguide unit of the projection board so as to project the image light onto an exit area of ​​the optical waveguide unit; A glasses-type terminal comprising:

13. A glasses-type terminal worn by a user, the projection optical system according to claim 1 , which is provided as at least one of a lens for a right eye and a lens for a left eye of the user, and which projects the image light onto the second surface while transmitting at least a part of light incident from the first surface to the eye of the user; a frame that fixes the projection optical system; a projection unit provided on the frame, which irradiates the projection light onto an incident area of ​​the optical waveguide unit of the projection board so as to project the image light onto an exit area of ​​the optical waveguide unit; Equipped with the projection unit has a polarization adjustment unit that adjusts the polarization direction of the projection light that is irradiated onto the incident area, the diffracted light reducing plate of the projection optical system is provided opposite to the first surface of the projection substrate, the polarization adjusting unit adjusts the polarization direction of the projection light so that the polarization direction of the image light coincides with the polarization direction of the light reduced by the diffracted light reducing plate. Glasses-type device.

14. the projection unit has a polarization adjustment unit that adjusts the polarization direction of the projection light that is irradiated onto the incident area, the diffracted light reducing plate of the projection optical system is provided opposite to the second surface of the projection substrate, the polarization adjusting unit adjusts the polarization direction of the projection light so that the polarization direction of the image light coincides with the polarization direction of the light transmitted by the diffracted light reducing plate. The eyeglass-type terminal according to claim 12.

15. A glasses-type terminal worn by a user, the projection optical system according to claim 1 , which is provided as at least one of a lens for a right eye and a lens for a left eye of the user, and which projects the image light onto the second surface while transmitting at least a part of light incident from the first surface to the eye of the user; a frame that fixes the projection optical system; a projection unit provided on the frame, which irradiates the projection light onto an incident area of ​​the optical waveguide unit of the projection board so as to project the image light onto an exit area of ​​the optical waveguide unit; Equipped with a plurality of projection substrates are fixed to the frame; the diffracted light reducing plate is provided on one of the plurality of projection boards on a side opposite to the user, or between the one projection board and the user, the projection unit irradiates the projection light beams having different wavelengths onto the incident areas provided on each of the plurality of projection boards, The emission areas provided on the plurality of projection substrates respectively at least partially overlap in a planar view, and the image light corresponding to the projection light irradiated from the projection unit onto the plurality of incidence areas is emitted from the second surfaces of the plurality of projection substrates respectively to the eyes of the user. Glasses-type device.

16. the projection unit includes a polarization adjustment unit that adjusts the polarization direction of at least one of the plurality of projection lights that are irradiated onto the incident area, the diffracted light reducing plate of the projection optical system is provided on the opposite side of the plurality of projection substrates from the user, the polarization adjustment unit adjusts the polarization direction of the projection light so that the polarization direction of at least one of the plurality of image lights coincides with the polarization direction of light reduced by the diffracted light reduction plate. The eyeglass-type terminal according to claim 15.

17. the projection unit includes a polarization adjustment unit that adjusts the polarization direction of at least one of the plurality of projection lights that are irradiated onto the incident area, the diffracted light reducing plate of the projection optical system is provided between one of the plurality of projection substrates and the user, the polarization adjustment unit adjusts the polarization direction of the projection light so that the polarization direction of the image light emitted from the one projection substrate among the plurality of image light beams coincides with the polarization direction of the light transmitted by the diffracted light reduction plate. The eyeglass-type terminal according to claim 15.