Display device and method for manufacturing light guide

Abstract

A display device (1) is provided with a curved light guide (30) and an image light emission unit (20) that outputs image light to the light guide (30). The light guide (30) has: a first light guide layer (31); a second light guide layer (32); and an optical element (40) that is disposed between the first light guide layer (31) and the second light guide layer (32) and diffracts and emits light (image light) propagating through the first light guide layer (31) and the second light guide layer (32). The thickness of the first light guide layer (31) is thinner than the thickness of the second light guide layer (32).

Description

Technical Field

[0001] The present disclosure relates to a display device and a method for manufacturing a light guide. Background Art

[0002] Patent Document 1 discloses an optical waveguide including a plurality of partial optical waveguides formed in a planar manner and having an optical filter. The optical waveguide includes a substrate, a hologram layer disposed on the substrate, and a cover layer disposed on the hologram layer.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2021-528681 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] However, the optical waveguide of Patent Document 1 is constructed by overlapping a substrate, a hologram layer, and a cover layer. When the curvature of the substrate is different from that of the cover layer, it becomes difficult to bond the substrate and the cover layer together, so a certain degree of bending accuracy is required in the substrate and the cover layer. In addition, it is considered to ensure the bending accuracy of the optical waveguide by pressing the substrate, the hologram layer, and the cover layer after overlapping them. In this case, the following problem occurs: deformation occurs in the light guide body such as the substrate and the cover layer.

[0008] Therefore, an object of the present disclosure is to provide a display device and a method for manufacturing a light guide that can suppress deformation occurring in a light guide.

[0009] Solutions for solving problems

[0010] A display device involved in one embodiment of the present disclosure comprises: a curved light guide; and an image light emitting portion, which outputs image light to the light guide, wherein the light guide has: a first light guide layer; a second light guide layer; and an optical element, which is arranged between the first light guide layer and the second light guide layer, and is used to diffract and emit light propagating in the first light guide layer and the second light guide layer, and the thickness of the first light guide layer is thinner than the thickness of the second light guide layer.

[0011] In addition, a method for manufacturing a light guide body involved in one embodiment of the present invention includes: a first step of bonding an optical element to a first light guide layer, wherein the optical element diffracts and emits light; and a second step of bonding the first light guide layer to which the optical element is bonded to the second light guide layer in such a manner that the optical element is arranged between the first light guide layer and the second light guide layer, wherein the second light guide layer is curved and the first light guide layer is thinner than the second light guide layer.

[0012] In addition, some of the specific methods can be implemented using systems, methods, integrated circuits, computer programs, or computer-readable recording media such as CD-ROMs, or using any combination of systems, methods, integrated circuits, computer programs, and recording media.

[0013] Effects of the Invention

[0014] According to the display device and the like of the present disclosure, deformation occurring in the light guide can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1A This is a schematic diagram showing an example of a vehicle provided with the display device according to the embodiment.

[0016] Figure 1B It is a schematic diagram showing a state where the display device and the vehicle according to the embodiment are viewed from the right direction.

[0017] Figure 2 It is a perspective view showing a display device according to an embodiment.

[0018] Figure 3 is a diagram showing a display device.

[0019] Figure 4 is a cross-sectional view showing a light guide.

[0020] Figure 5 : is a flowchart showing a method for manufacturing a light guide.

[0021] Figure 6 It is a perspective view showing a display device according to another modification example. DETAILED DESCRIPTION

[0022] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0023] In addition, the embodiments described below all represent general or specific examples. The numerical values, shapes, materials, constituent elements, configuration positions and connection methods of constituent elements, steps, and the order of steps shown in the following embodiments are examples and are not intended to limit the present disclosure. In addition, the constituent elements of the following embodiments that are not recorded in the independent claims are described as arbitrary constituent elements.

[0024] In addition, each figure is a schematic diagram, and does not necessarily illustrate strictly. In addition, in each figure, the same reference numeral is attached|subjected to the same component.

[0025] In addition, in the following embodiments, expressions such as rectangular shape and substantially the entire surface are used. For example, rectangular shape and the entire surface not only mean completely rectangular and the entire surface, but also mean substantially rectangular and the entire surface, that is, including an error of about a few percent. In addition, rectangular shape and substantially the entire surface mean rectangular and the entire surface within the scope that can achieve the effect of the present disclosure. The same is true for other situations where expressions such as "shape" and "substantially" are used.

[0026] (Implementation Method)

[0027] <Structure: Display device 1>

[0028] First, use Figure 1A to Figure 4 The structure of the display device 1 will be described.

[0029] Figure 1A It is a schematic diagram showing an example of a vehicle 2 provided with the display device 1 according to the embodiment. Figure 1B 1 is a schematic diagram showing a state where the display device 1 and the vehicle 2 according to the embodiment are viewed in the right direction (X-axis positive direction). Figure 2 It is a perspective view showing the display device 1 according to the embodiment. Figure 3 2 is a diagram showing the display device 1 . Figure 3 (a) is a front view of the display device 1, Figure 3 (b) is a side view of the display device 1, Figure 3 (c) is a front view of the display device 1. Figure 4 is a cross-sectional view showing the light guide 30 .

[0030] exist Figure 2 For example, the arrangement direction of the returning optical element 42 relative to the incident optical element 41 is defined as the positive direction of the X-axis, the arrangement direction of the returning optical element 42 relative to the emitting optical element 43 is defined as the positive direction of the Y-axis, and the arrangement direction of the incident optical element 41 relative to the image light emitting portion 20 is defined as the positive direction of the Z-axis.

[0031] like Figure 1A and Figure 1B As shown, the display device 1 is arranged on a dashboard (also called an instrument panel) of a vehicle 2 such as a car, for example. A front window 3 (also called a front shield) is arranged above the dashboard of the vehicle 2. A light guide 30 of the display device 1 is arranged between the dashboard and the front window 3. The light guide 30 can emit image light toward the front window 3. The specific structure of the light guide 30 will be described later.

[0032] In the display device 1, for a user such as a driver or a fellow passenger, the image light emitted from the light guide 30 is reflected by the front window 3, so that the image light can enter the eyes of the driver. That is, the display device 1 projects the image represented by the image light emitted by the image light emitting unit 20 in front of the front window 3, so that a virtual image corresponding to the image can be displayed on the front window 3. The image light is light representing the image, and is light that displays the virtual image in front of the front window 3. The image is a still image or a moving image, and is an image representing numbers, characters, graphics, etc.

[0033] like Figure 1B and Figure 2 As shown, the display device 1 includes an image light emitting unit 20 and a light guide 30 .

[0034] [Image light emitting unit 20]

[0035] The image light emitting unit 20 is an image generating device that outputs image light to the light guide 30. The image light emitting unit 20 can project a predetermined image onto the front window 3 via the light guide 30 by emitting image light representing an image having a rectangular shape. The image light emitting unit 20 can emit image light from a rectangular emitting surface. The image light emitted from the image light emitting unit 20 is incident on the light guide 30 and is emitted from the light guide 30 through the light guide 30, thereby irradiating the front window 3. As a result, the image light is reflected by the front window 3, so that the image is projected onto the front window 3, and the virtual image is recognized by the user.

[0036] The image light emitting unit 20 includes a plurality of emitters, a plurality of dichroic mirrors, a condenser lens, a reflecting mirror, and an emitting surface.

[0037] Each of the plurality of emitters is different from the others and is used to emit light of a prescribed wavelength band. Each of the plurality of dichroic mirrors is arranged on the light emitted by the emitter, and can reflect the light of a prescribed wavelength band and transmit the light of other wavelength bands. The focusing lens is a lens that converges the light emitted through the dichroic mirrors to a plurality of reflectors. The emission surface is a screen such as a microlens array, a liquid crystal display element such as a liquid crystal display (LCD), and by irradiating light of a plurality of wavelength bands from the reflector side, the transmitted light can be emitted as image light.

[0038] [Light guide 30]

[0039] like Figure 2 and Figure 3 As shown, the light guide 30 is a hologram light guide that displays an image represented by image light to a user. The light guide 30 has light transmittance and can elongate and emit the image represented by the image light emitted by the image light emitting unit 20 in the X-axis direction and the Y-axis direction.

[0040] The light guide 30 is in a curved rectangular shape. Specifically, the light guide 30 is in a rectangular shape when viewed along the Z-axis direction, and is in a curved shape that is warped upward on the negative Y-axis side in the Y-axis direction. The warping upward on the negative Y-axis side in the Y-axis direction means that the light guide 30 is bent in a manner that protrudes toward the negative Z-axis side.

[0041] The light guide 30 is disposed in the vehicle 2 so as to face the image light emitting unit 20 and the front window 3 .

[0042] The light guide 30 is formed with an incident surface 31 a and an emitting surface 31 b .

[0043] The incident surface 31a is arranged to face the emission surface of the image light emission unit 20. The image light emitted from the emission surface of the image light emission unit 20 is incident on the incident surface 31a. The incident surface 31a is a part of the back surface of the rectangular light guide 30. The back surface is the surface of the light guide 30 on the opposite side to the emission surface 31b.

[0044] The emission surface 31b emits the image light incident from the incident surface 31a and propagating inside the light guide 30 toward the front window 3. The emission surface 31b faces the front window 3 and is separated from the front window 3 by a predetermined distance. The emission surface 31b is a part of the surface of the light guide 30.

[0045] like Figure 3 and Figure 4 As shown, the light guide body 30 includes a first light guide layer 31 , a second light guide layer 32 , an optical element 40 , a first adhesive member 51 , and a second adhesive member 52 .

[0046] The first light guide layer 31 is arranged at a position closer to the front window 3 than the second light guide layer 32. In addition, the second light guide layer 32 is arranged at a position closer to the image light emitting portion 20 than the first light guide layer 31. Therefore, an incident surface 31a facing the image light emitting portion 20 is formed in the second light guide layer 32. The incident surface 31a is a surface facing the image light emitting portion 20, and is a surface that is a part of the back surface of the second light guide layer 32. In addition, an emission surface 31b is formed in the first light guide layer 31 so as to face the front window 3. The emission surface 31b is a surface that is a part of the surface of the first light guide layer 31.

[0047] The light guide 30 has a laminated structure in which the optical element 40 is sandwiched between the first light guide layer 31 and the second light guide layer 32. Specifically, the optical element 40 is laminated on the surface 32a of the second light guide layer 32 via the first adhesive member 51, and the first light guide layer 31 is laminated via the second adhesive member 52. The surface 32a of the second light guide layer 32 is the surface of the second light guide layer 32 on the opposite side to the incident surface 31a, and is the surface on which the second adhesive member 52 is disposed.

[0048] The first light guide layer 31 is in a film shape. The first light guide layer 31 is made of a light-transmitting material such as glass. The first light guide layer 31 can be bent and stretched at room temperature. In addition, the material of the first light guide layer 31 is not limited to glass. For example, the material of the first light guide layer 31 may also be made of a light-transmitting resin film or the like.

[0049] In addition, the second light guide layer 32 is in a curved plate shape. The second light guide layer 32 is made of a light-transmitting material such as glass, for example. The second light guide layer 32 maintains a curved shape at room temperature. Therefore, the first light guide layer 31 is bonded along the surface 32a of the second light guide layer 32 to form a curved shape. In other words, the first light guide layer 31 is arranged along the shape of the surface 32a of the second light guide layer 32.

[0050] like Figure 4 As shown, the thickness of the first light guide layer 31 is thicker than the thickness of the first adhesive member 51, the thickness of the second adhesive member 52, and the thickness of the optical element 40. In addition, the thickness of the first light guide layer 31 is thinner than the thickness of the second light guide layer 32. The thickness of the first light guide layer 31 is less than 1 / 5 of the thickness of the second light guide layer 32. In other words, the first light guide layer 31 is thick enough to be bent and stretched to be arranged along the shape of the surface 32a of the second light guide layer 32. The thickness of the first light guide layer 31 is, for example, 0.2 mm. In addition, the thickness of the second light guide layer 32 is, for example, 2.8 mm. The thickness of the optical element 40 is, for example, 2 μm. The thickness of the first adhesive member 51 and the thickness of the second adhesive member 52 are, for example, 0.1 mm. The thickness of the first light guide layer 31, the thickness of the second light guide layer 32, the thickness of the optical element 40, the thickness of the first adhesive member 51, and the thickness of the second adhesive member 52 are merely examples and are not limited to the present disclosure.

[0051] The second light guide layer 32 has a surface 32a on the side of the first light guide layer 31 and a back surface 32b on the side opposite to the surface 32a. The surface 32a of the second light guide layer 32 is rougher than the back surface 32b of the second light guide layer 32. That is, the surface roughness of the surface 32a of the second light guide layer 32 is greater than the surface roughness of the back surface 32b of the second light guide layer 32. When a mold is used to mold the curved second light guide layer 32, the second light guide layer 32 may be molded by bringing the surface that becomes the surface 32a of the second light guide layer 32 into contact with the mold. The surface 32a of the second light guide layer 32 is an example of a first surface. The back surface 32b of the second light guide layer 32 is an example of a second surface.

[0052] like Figure 2 and Figure 3 As shown, the optical element 40 is a light-transmitting hologram element that diffracts and emits light propagating in the first light guide layer 31 and the second light guide layer 32. The optical element 40 is bonded to the first light guide layer 31 by a first bonding member 51 and bonded to the second light guide layer 32 by a second bonding member 52, thereby being arranged between the first light guide layer 31 and the second light guide layer 32.

[0053] In addition, the optical element 40 has a light-transmitting optical layer 40a and a light-transmitting protective layer 40b. The optical layer 40a is an optical element body that diffracts light propagating in the first light guide layer 31 and the second light guide layer 32. The protective layer 40b is provided on the back side of the optical layer 40a, that is, the surface of the optical layer 40a on the side of the second light guide layer 32. The protective layer 40b contains a material having a waterproof effect, such as polyamide, cyclic olefin copolymer, etc. Thus, the protective layer 40b can protect the optical layer 40a. In addition, the optical element 40 may not have the protective layer 40b, and the protective layer 40b is not an essential component of the optical element 40.

[0054] Such an optical element 40 includes an incident optical element 41 , a return optical element 42 , and an emission optical element 43 .

[0055] The incident optical element 41 and the folding optical element 42 are arranged in the X-axis direction. The folding optical element 42 and the emitting optical element 43 are arranged in the Y-axis direction. In addition, the incident optical element 41 is arranged to overlap with the incident surface 31a of the light guide body 30 when viewed along the Z-axis direction, and overlap with the emitting surface of the image light emitting portion 20 arranged on the negative side of the Z-axis direction of the second light guide layer 32.

[0056] The incident optical element 41 is in the shape of a rectangular plate. The incident optical element 41 may also be bent along the light guide 30 .

[0057] The incident optical element 41 emits the image light emitted from the emission surface of the image light emitting section 20 and traveling in the positive direction of the Z axis, thereby causing the image light to be incident on the folding optical element 42. Specifically, the incident optical element 41 can emit the first deflected light (image light) after deflecting the image light of the image light emitting section 20, that is, the image light incident from the incidence surface 31a. More specifically, when the image light incident on the light guide 30 propagates in the light guide 30, the incident optical element 41 deflects the image light by diffraction according to the diffraction efficiency of the incident optical element 41, thereby emitting it as the first deflected light propagating in the positive direction of the X axis. The first deflected light deflected by the incident optical element 41 by diffraction is incident on the folding optical element 42.

[0058] The folding optical element 42 is arranged on the positive X-axis direction side of the incident optical element 41 , ie, the light emitting side of the incident optical element 41 , and is arranged on the positive Y-axis direction side of the emitting optical element 43 , ie, the light incident side of the emitting optical element 43 .

[0059] The folding optical element 42 is in the shape of a rectangular plate that is elongated along the X-axis direction. The folding optical element 42 may be curved along the light guide 30 .

[0060] The first deflected light emitted from the incident optical element 41 is incident on the folding optical element 42. The folding optical element 42 further deflects the first deflected light deflected by the incident optical element 41 by diffraction, thereby emitting the deflected second deflected light (image light). Specifically, whenever the first deflected light that has passed through the incident optical element 41 is incident (transmitted), the folding optical element 42 emits the second deflected light (image light) after the incident first deflected light is further deflected by diffraction toward the emitting optical element 43. More specifically, when the first deflected light incident on the folding optical element 42 propagates in the light guide 30 along the positive direction of the X-axis, the folding optical element 42 further deflects the first deflected light by diffraction according to the diffraction efficiency of the folding optical element 42. At this time, the folding optical element 42 plays a role in stretching the image of the image light along the X-axis direction. As a result, the folding optical element 42 emits the second deflected light stretched along the X-axis direction along the negative direction of the Y-axis. The second deflected light deflected by diffraction in the folding optical element 42 enters the emission optical element 43 .

[0061] The emission optical element 43 is disposed on the negative side of the Y axis relative to the folding optical element 42 and faces the light incident side of the folding optical element 42. The emission optical element 43 is disposed so as to overlap with and face the emission surface 31b of the light guide 30.

[0062] The emission optical element 43 has a rectangular shape when viewed along the Z-axis direction, and has a curved plate shape that is warped upward in the negative Y-axis direction with respect to the Y-axis direction.

[0063] The second deflected light emitted from the folding optical element 42 is incident on the emission optical element 43. The emission optical element 43 further deflects the second deflected light deflected by the folding optical element 42 by diffraction, thereby emitting the deflected third deflected light (image light) to the outside of the light guide 30. Specifically, whenever the second deflected light that has passed through the folding optical element 42 is incident (transmitted), the emission optical element 43 emits the third deflected light (image light) after the incident second deflected light is further deflected by diffraction at a predetermined emission angle. More specifically, when the second deflected light deflected by the folding optical element 42 propagates in the light guide 30 along the negative direction of the Y axis, the emission optical element 43 further deflects the second deflected light by diffraction according to the diffraction efficiency of the emission optical element 43. At this time, the emission optical element 43 plays a role in further elongating the image of the second deflected light elongated along the X-axis direction along the approximate Y-axis direction. Thus, the emission optical element 43 emits the third deflected light elongated along the X-axis direction and the approximately Y-axis direction to the outside of the light guide 30 at a predetermined emission angle. In other words, the emission optical element 43 further elongates the second deflected light emitted by the return optical element 42 along the approximately Y-axis direction, thereby emitting the third deflected light expanded in the X-axis direction and the Y-axis direction at a predetermined emission angle. In the present embodiment, the emission optical element 43 emits the third deflected light along the positive direction of the Z-axis toward the front window 3.

[0064] Here, the predetermined emission angle is the emission angle of the third deflected light emitted from the emission surface of the emission optical element 43 , and is the angle of the emitted light with respect to the normal line of the emission surface of the emission optical element 43 .

[0065] In addition, the emission optical element 43 may diverge the emitted image light so that the emission angle of the third deflected light is different. The emission optical element 43 may also make the emission angle different according to the position (portion) on the emission optical element 43 when deflecting the incident image light by diffraction. Thus, the emission optical element 43 can make the emission angle of a part of the image light in the image light deflected by the emission optical element 43 by diffraction different.

[0066] like Figure 3 and Figure 4As shown, the first adhesive member 51 is an adhesive having light transmittance. The first adhesive member 51 bonds the first light guide layer 31 to the optical element 40. Specifically, the first adhesive member 51 (51a, 51b, 51c) is stacked on the back side of the first light guide layer 31, and is used to bond the first light guide layer 31 to the optical element 40. More specifically, the first adhesive member 51a bonds the first light guide layer 31 to the incident optical element 41. In addition, the first adhesive member 51b bonds the first light guide layer 31 to the return optical element 42. In addition, the first adhesive member 51c bonds the first light guide layer 31 to the emission optical element 43. The back side of the first light guide layer 31 is the surface of the first light guide layer 31 on the opposite side to the emission surface 31b, and is the surface on which the first adhesive member 51 is configured.

[0067] The second adhesive member 52 is an adhesive having light transmittance. The second adhesive member 52 bonds the second light guide layer 32 to the optical element 40. Specifically, the second adhesive member 52 (52a, 52b, 52c) is stacked on the surface 32a of the second light guide layer 32, and is used to bond the second light guide layer 32 to the optical element 40. More specifically, the second adhesive member 52a bonds the second light guide layer 32 to the incident optical element 41. In addition, the second adhesive member 52b bonds the second light guide layer 32 to the return optical element 42. In addition, the second adhesive member 52c bonds the second light guide layer 32 to the emission optical element 43.

[0068] <Propagation Path of Image Light>

[0069] Next, the propagation path of the image light in this embodiment will be described.

[0070] In such a display device 1, when the image light emitting unit 20 emits image light, the image light enters the incident surface 31a of the second light guide layer 32 in the light guide body 30. The image light entering the second light guide layer 32 passes through the second light guide layer 32 and the second adhesive member 52a and enters the incident optical element 41.

[0071] The image light incident on the incident optical element 41 is deflected by diffraction and emitted as first deflected light from the incident optical element 41. The first deflected light emitted from the incident optical element 41 passes through the first adhesive member 51a, the light guide 30, and the second adhesive member 52b and then enters the folding optical element 42.

[0072] The first deflected light incident on the reflecting optical element 42 is further deflected by diffraction and emitted as second deflected light from the reflecting optical element 42. The second deflected light emitted from the reflecting optical element 42 passes through the first adhesive member 51b, the light guide 30, and the second adhesive member 52c and then enters the emission optical element 43.

[0073] The second deflected light incident on the emission optical element 43 is further deflected by diffraction, and is emitted from the emission optical element 43 as the third deflected light. The third deflected light emitted from the emission optical element 43 passes through the first adhesive member 51c and the light guide 30, and is emitted from the emission surface 31b of the light guide 30. The third deflected light emitted from the emission surface 31b of the light guide 30 is irradiated to the front window 3. Thus, since the third deflected light, that is, the image light, is reflected by the front window 3, an image is projected onto the front window 3. As a result, the user can recognize the virtual image projected onto the front window 3.

[0074] <Manufacturing method>

[0075] Next, a method for manufacturing the light guide 30 in this embodiment will be described.

[0076] Figure 5 1 is a flowchart showing a method for manufacturing the light guide 30 .

[0077] The first light guide layer 31 in a film shape, the second light guide layer 32 in a curved shape, the optical element 40 , the first adhesive member 51 , and the second adhesive member 52 are prepared in advance.

[0078] First, if Figure 5 As shown, an operator or a manufacturing device adheres the optical element 40 that diffracts and emits light to the first light guide layer 31 ( S1 : first step). That is, in the first step, the optical element 40 is adhered to the first light guide layer 31 via the first adhesive member 51 .

[0079] Next, the operator or the manufacturing device adheres the first light guide layer 31 to which the optical element 40 is adhered to the surface 32a of the second light guide layer 32 in such a manner that the optical element 40 is arranged between the first light guide layer 31 and the second light guide layer 32 (S2: second step). That is, in the second step, the first light guide layer 31 to which the optical element 40 is adhered is adhered to the second light guide layer 32 by means of the second adhesive member 52. The optical element 40 and the first light guide layer 31 having a thin thickness do not need to be pre-bent and molded like the curved second light guide layer 32. Therefore, for example, by pressing the first light guide layer 31 to which the optical element 40 is adhered to the second light guide layer 32 using a roller or the like, the first light guide layer 31 to which the optical element 40 is adhered can be adhered to the second light guide layer 32 by means of the second adhesive member 52.

[0080] Thus, the light guide body 30 is obtained in which the second light guide layer 32 , the second adhesive member 52 , the optical element 40 , the first adhesive member 51 , and the first light guide layer 31 are stacked in this order.

[0081] <Effects>

[0082] Next, the effects of the display device 1 in this embodiment will be described.

[0083] As described above, the display device 1 according to the present embodiment includes the curved light guide 30 and the image light emitting unit 20 for outputting image light to the light guide 30. The light guide 30 includes the first light guide layer 31, the second light guide layer 32, and the optical element 40, which is disposed between the first light guide layer 31 and the second light guide layer 32 and diffracts and emits light (image light) propagating through the first light guide layer 31 and the second light guide layer 32. The first light guide layer 31 is thinner than the second light guide layer 32.

[0084] Thus, the thin first light guide layer 31 is arranged on the second light guide layer 32 via the optical element 40 so as to follow the surface shape of the curved second light guide layer 32. Therefore, in the display device 1 of the present embodiment, it is difficult for the first light guide layer 31 and the second light guide layer 32 to be deformed, compared with a case where a thick curved first light guide layer and a thick curved second light guide layer are overlapped and then pressed.

[0085] Therefore, the display device 1 of the embodiment can suppress deformation occurring in the light guide 30 . As a result, when the image light emitted from the light guide 30 is irradiated onto the front window 3 , unevenness occurring in the image represented by the image light displayed on the front window 3 can be suppressed.

[0086] In particular, since the thickness of the first light guide layer 31 is thin, the first light guide layer 31 can be arranged along the curved second light guide layer 32. Therefore, the first light guide layer 31 and the second light guide layer 32 do not need to be formed so that the curvature of the first light guide layer 31 coincides with the curvature of the second light guide layer 32. Therefore, it is possible to suppress an increase in the manufacturing cost when manufacturing the display device 1.

[0087] In addition, the display device 1 according to the present embodiment includes a curved light guide 30 and an image light emitting unit 20 for outputting image light to the light guide 30. In addition, the light guide 30 includes a first light guide layer 31, a second light guide layer 32, and an optical element 40, which is disposed between the first light guide layer 31 and the second light guide layer 32 and is used to diffract and emit light propagating in the first light guide layer 31 and the second light guide layer 32. In addition, the second light guide layer 32 maintains a curved shape at room temperature. Furthermore, the first light guide layer 31 can be bent and stretched at room temperature.

[0088] In this case, the same effects as described above are achieved.

[0089] In the display device 1 according to the present embodiment, the first light guide layer 31 is in a film shape, and the second light guide layer 32 is in a curved shape. The first light guide layer 31 is bonded along the surface 32 a of the second light guide layer 32 to form a curved shape.

[0090] According to this, since the first light guide layer 31 has flexibility, the first light guide layer 31 can be arranged on the second light guide layer 32 along the surface shape of the second light guide layer 32 without causing deformation of the first light guide layer 31 and the second light guide layer 32. Therefore, in the display device 1 of this embodiment, it is difficult for the first light guide layer 31 and the second light guide layer 32 to be deformed.

[0091] The display device 1 according to the present embodiment further includes a first adhesive member 51 that bonds the first light guide layer 31 and the optical element 40 together, and a second adhesive member 52 that bonds the second light guide layer 32 and the optical element 40 together.

[0092] According to this, the first light guide layer 31 can be bonded to the optical element 40 by the first adhesive member 51, and the optical element 40 can be bonded to the thick second light guide layer 32 by the second adhesive member 52. Thus, the first light guide layer 31 and the optical element 40 can be arranged on the second light guide layer 32 in such a manner that the curvature of the first light guide layer 31 coincides with the curvature of the second light guide layer 32. Therefore, in the display device 1 of the present embodiment, deformation of the first light guide layer 31 and the second light guide layer 32 is unlikely to occur.

[0093] In the display device 1 according to the present embodiment, the second light guide layer 32 has a surface 32a (first surface) on the first light guide layer 31 side and a back surface 32b (second surface) located opposite to the surface 32a. The surface 32a is rougher than the back surface 32b.

[0094] According to this, the light propagating in the first light guide layer 31 and the second light guide layer 32 is totally reflected at the back surface 32b of the second light guide layer 32, so that the light can be propagated in a desired direction. Therefore, the light can be emitted in a desired direction from the emission surface 31b of the light guide body 30. As a result, when the image light emitted from the light guide body 30 is irradiated to the front window 3, unevenness generated in the image represented by the image light displayed on the front window 3 can be suppressed.

[0095] In the display device 1 according to the present embodiment, the thickness of the first light guide layer 31 is equal to or less than 1 / 5 of the thickness of the second light guide layer 32 .

[0096] Thus, the thin first light guide layer 31 can be arranged on the second light guide layer 32 along the surface shape of the second light guide layer 32 without causing deformation of the first light guide layer 31 and the second light guide layer 32. Therefore, in the display device 1 of the present embodiment, deformation of the first light guide layer 31 and the second light guide layer 32 is unlikely to occur.

[0097] In the display device 1 according to the present embodiment, the thickness of the first light guide layer 31 is thicker than the thickness of the first adhesive member 51 , the thickness of the second adhesive member 52 , and the thickness of the optical element 40 .

[0098] Accordingly, the first light guide layer 31, the first adhesive member 51, the second adhesive member 52, and the optical element 40, which are thin in thickness, can be arranged along the surface shape of the second light guide layer 32 in a manner that does not cause deformation of the first light guide layer 31 and the second light guide layer 32. Therefore, in the display device 1 of the present embodiment, it is difficult for the first light guide layer 31 and the second light guide layer 32 to be deformed.

[0099] In addition, the manufacturing method of the light guide body 30 according to the present embodiment includes: a first step of bonding an optical element 40 to a first light guide layer 31, wherein the optical element 40 diffracts and emits light; and a second step of bonding the first light guide layer 31 to which the optical element 40 is bonded to a second light guide layer 32 in such a manner that the optical element 40 is disposed between the first light guide layer 31 and the second light guide layer 32. In addition, the second light guide layer 32 is curved. Furthermore, the thickness of the first light guide layer 31 is thinner than the thickness of the second light guide layer 32.

[0100] According to this, after the optical element 40 is bonded to the thin first light guide layer 31, the stacked body of the first light guide layer 31 and the optical element 40 can be arranged along the surface shape of the thick curved second light guide layer 32. Therefore, in the display device 1 of this embodiment, it is difficult for the first light guide layer 31 and the second light guide layer 32 to be deformed, compared with the case where the light guide body is manufactured by overlapping the thick curved first light guide layer and the thick curved second light guide layer.

[0101] Therefore, according to the method of manufacturing the light guide 30 in the embodiment, deformation occurring in the light guide 30 can be suppressed.

[0102] In addition, in the first step of the manufacturing method of the light guide body 30 involved in this embodiment, the optical element 40 is bonded to the first light guide layer 31 by means of the first adhesive member 51, and in the second step, the first light guide layer 31 bonded with the optical element 40 is bonded to the second light guide layer 32 by means of the second adhesive member 52.

[0103] According to this, after the first light guide layer 31 is bonded to the optical element 40 by the first adhesive member 51, the laminated body of the first light guide layer 31 and the optical element 40 can be bonded to the thick second light guide layer 32 by the second adhesive member 52. Thus, the first light guide layer 31 and the optical element 40 can be arranged on the second light guide layer 32 in such a manner that the curvature of the first light guide layer 31 coincides with the curvature of the second light guide layer 32. Therefore, in the display device 1 of the present embodiment, deformation of the first light guide layer 31 and the second light guide layer 32 is unlikely to occur.

[0104] (Other Modifications)

[0105] The display device and the method for manufacturing the light guide body involved in the present disclosure are described above based on the above-mentioned embodiments, but the present disclosure is not limited to these embodiments. As long as it does not deviate from the main purpose of the present disclosure, the various deformations that the technicians in this field can also be included in the scope of the present disclosure.

[0106] In the manufacturing method of the display device 1 and the light guide body 30 involved in the present disclosure, the first light guide layer 31 may be arranged at a position on the negative side of the Z axis relative to the optical element 40, and the second light guide layer 32 may be arranged at a position on the positive side of the Z axis relative to the optical element 40. In this case, the emission surface 31b is formed on a part of the surface 32a of the second light guide layer 32, and the incident surface 31a is formed on a part of the back surface of the first light guide layer 31. In addition, the optical element 40 may be attached to the surface of the first light guide layer 31 via the first adhesive member 51, or the first light guide layer 31 to which the optical element 40 is attached may be attached to the back surface 32b of the second light guide layer 32 via the second adhesive member 52. The back surface 32b of the second light guide layer 32 is rougher than the surface 32a of the second light guide layer 32. In addition, the thickness of the first light guide layer 31 is thinner than the thickness of the second light guide layer 32. In addition, the thickness of the first light guide layer 31 is thicker than the thickness of the first adhesive member 51, the thickness of the second adhesive member 52, and the thickness of the optical element 40. The thickness of the first light guide layer 31 is 1 / 5 or less of the thickness of the second light guide layer 32. The front surface 32a of the second light guide layer 32 is an example of the second surface. The back surface 32b of the second light guide layer 32 is an example of the first surface.

[0107] In addition, in the manufacturing method of the display device 1 and the light guide body 30 involved in the present disclosure, the first adhesive member 51, the optical element 40, and the second adhesive member 52 are exemplified as being included in the first light guide layer 31 and the second light guide layer 32, but the present invention is not limited thereto. The first adhesive member 51, the optical element 40, and the second adhesive member 52 may also be arranged to reach the back surface of the first light guide layer 31 and the edge of the surface 32a of the second light guide layer 32.

[0108] In addition, if Figure 6 As shown, in the display device 1a involved in the present disclosure, one light guide 30 is illustrated, but the display device 1a may also include three light guides 30 (light guide A, light guide B, and light guide C). The light guide A, light guide B, and light guide C have the same structure except that the wavelength selection components of the incident optical element 41A of the light guide A, the incident optical element 41B of the light guide B, and the incident optical element 41C of the light guide C are different. Figure 6is a perspective view showing a display device 1a according to another modification. Figure 6 In the case of , the light guide A may be arranged so that the incident surface 31a of the light guide A faces the image light emitting portion 20. The light guide B may face the light guide A at a predetermined interval and be arranged on the positive direction side of the Z axis of the light guide A. The light guide C may face the light guide B at a predetermined interval and be arranged on the positive direction side of the Z axis of the light guide B. That is, the light guide A, the light guide B, and the light guide C are arranged at predetermined intervals in a manner overlapping along the positive direction of the Z axis in this arrangement order, thereby forming an air layer between the light guide A and the light guide B, and between the light guide B and the light guide C. The incident optical elements 41A, 41B, 41C of the light guide A, the light guide B, and the light guide C may be wavelength-selective dichroic mirrors. The light guide A may also emit a third deflected light of a first wavelength component corresponding to blue among the wavelength components included in the incident image light toward the light guide B. In addition, the incident optical element 41A of the light guide A may also emit image light other than the first wavelength component toward the light guide B. Image light other than the first wavelength component may also be incident on the light guide B, and third deflected light of a second wavelength component other than the first wavelength component corresponding to green among the wavelength components included in the incident image light may be emitted toward the light guide C. In addition, the incident optical element 41B of the light guide B may also emit image light other than the first wavelength component and the second wavelength component toward the light guide C. In addition, the light guide B may allow the third deflected light of the first wavelength component emitted by the light guide A to pass through and then emit it toward the light guide C. The light guide C may also allow image light other than the first wavelength component and the second wavelength component to be incident, and emit third deflected light of a third wavelength component other than the first wavelength component and the second wavelength component toward the front window 3, corresponding to red among the wavelength components included in the incident image light. In addition, the light guide C may transmit the third deflected light of the first wavelength component emitted from the light guide A and the third deflected light of the second wavelength component emitted from the light guide B, and emit them toward the front window 3 .

[0109] In addition, various modifications that can be conceived by those skilled in the art to the above-described embodiments and embodiments achieved by arbitrarily combining components and functions in the embodiments within a scope not departing from the gist of the present disclosure are also included in the present disclosure.

[0110] (Note)

[0111] Next, features of the display device and the method for manufacturing the light guide described based on the above-mentioned embodiments will be described.

[0112] <Technology 1>

[0113] A display device comprising:

[0114] a curved light guide; and

[0115] an image light emitting unit configured to output image light to the light guide,

[0116] Wherein, the light guide has:

[0117] a first light guide layer;

[0118] a second light guide layer; and

[0119] an optical element, which is disposed between the first light guide layer and the second light guide layer and is used to diffract and emit the light propagating in the first light guide layer and the second light guide layer,

[0120] The thickness of the first light guide layer is thinner than that of the second light guide layer.

[0121] <Technology 2>

[0122] The display device according to technique 1, wherein:

[0123] The first light guide layer is in the form of a film,

[0124] The second light guide layer is curved.

[0125] The first light guide layer is formed into a curved shape by being bonded along the second light guide layer.

[0126] <Technology 3>

[0127] A display device comprising:

[0128] a curved light guide; and

[0129] an image light emitting unit configured to output image light to the light guide,

[0130] Wherein, the light guide has:

[0131] a first light guide layer;

[0132] a second light guide layer; and

[0133] an optical element, which is disposed between the first light guide layer and the second light guide layer and is used to diffract and emit the light propagating in the first light guide layer and the second light guide layer,

[0134] The second light guiding layer maintains a curved shape at room temperature.

[0135] The first light guiding layer can be bent and stretched at room temperature.

[0136] <Technique 4>

[0137] The display device according to any one of techniques 1 to 3, further comprising:

[0138] a first bonding member bonding the first light guide layer to the optical element; and

[0139] A second bonding member bonds the second light guide layer to the optical element.

[0140] <Technique 5>

[0141] The display device according to any one of techniques 1 to 4, wherein:

[0142] The second light guide layer has a first surface on the first light guide layer side and a second surface on the side opposite to the first surface.

[0143] The first surface is rougher than the second surface.

[0144] <Technique 6>

[0145] The display device according to any one of techniques 1 to 5, wherein:

[0146] The thickness of the first light guide layer is 1 / 5 or less of the thickness of the second light guide layer.

[0147] <Technique 7>

[0148] The display device according to technique 4, wherein:

[0149] The thickness of the first light guide layer is thicker than the thickness of the first adhesive member, the thickness of the second adhesive member, and the thickness of the optical element.

[0150] <Technology 8>

[0151] A method for manufacturing a light guide, comprising:

[0152] The first step is to bond an optical element to the first light guide layer, wherein the optical element diffracts and emits light; and

[0153] In a second step, the first light guide layer to which the optical element is bonded is bonded to the second light guide layer in such a manner that the optical element is disposed between the first light guide layer and the second light guide layer.

[0154] Wherein, the second light guide layer is curved.

[0155] The thickness of the first light guide layer is thinner than that of the second light guide layer.

[0156] <Technique 9>

[0157] The method for manufacturing a light guide according to technique 8, wherein:

[0158] In the first step, the optical element is bonded to the first light guide layer by a first bonding member.

[0159] In the second step, the first light guide layer to which the optical element is bonded is bonded to the second light guide layer via a second bonding member.

[0160] Industrial Applicability

[0161] The present disclosure can be used for a head-up display device of a vehicle, etc.

[0162] Description of Reference Numerals

[0163] 1, 1a: display device; 20: image light emitting part; 30, A, B, C: light guide body; 31: first light guide layer; 32: second light guide layer; 32a: surface of second light guide layer; 32b: back side of second light guide layer; 40: optical element; 41, 41A, 41B, 41C: incident optical element (optical element); 42: return optical element (optical element); 43: emission optical element (optical element); 51, 51a, 51b, 51c: first adhesive member; 52, 52a, 52b, 52c: second adhesive member.

Claims

1. A display device comprising: a curved light guide; and an image light emitting unit configured to output image light to the light guide, in, The light guide has: a first light guide layer; a second light guide layer; as well as an optical element, which is disposed between the first light guide layer and the second light guide layer and is used to diffract and emit the light propagating in the first light guide layer and the second light guide layer, The thickness of the first light guide layer is thinner than that of the second light guide layer.

2. The display device according to claim 1, wherein: The first light guide layer is in the form of a film, The second light guide layer is curved. The first light guide layer is formed into a curved shape by being bonded along the second light guide layer.

3. A display device comprising: a curved light guide; and an image light emitting unit configured to output image light to the light guide, in, The light guide has: a first light guide layer; a second light guide layer; as well as an optical element, which is disposed between the first light guide layer and the second light guide layer and is used to diffract and emit the light propagating in the first light guide layer and the second light guide layer, The second light guiding layer maintains a curved shape at room temperature. The first light guiding layer can be bent and stretched at room temperature.

4. The display device according to any one of claims 1 to 3, wherein: Also available: a first bonding member bonding the first light guide layer to the optical element; and A second bonding member bonds the second light guide layer to the optical element.

5. The display device according to any one of claims 1 to 3, wherein: The second light guide layer has a first surface on the first light guide layer side and a second surface on the side opposite to the first surface. The first surface is rougher than the second surface.

6. The display device according to any one of claims 1 to 3, wherein: The thickness of the first light guide layer is 1 / 5 or less of the thickness of the second light guide layer.

7. The display device according to claim 4, wherein: The thickness of the first light guide layer is thicker than the thickness of the first adhesive member, the thickness of the second adhesive member, and the thickness of the optical element.

8. A method for manufacturing a light guide, comprising: The first step is to bond an optical element to the first light guide layer, wherein the optical element diffracts and emits light; as well as In a second step, the first light guide layer to which the optical element is bonded is bonded to the second light guide layer in such a manner that the optical element is disposed between the first light guide layer and the second light guide layer. Wherein, the second light guide layer is curved. The thickness of the first light guide layer is thinner than that of the second light guide layer.

9. The method for manufacturing a light guide according to claim 8, wherein: In the first step, the optical element is bonded to the first light guide layer by a first bonding member. In the second step, the first light guide layer to which the optical element is bonded is bonded to the second light guide layer via a second bonding member.

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