Optical member and image projection device

Abstract

To provide an optical member that can appropriately split a plurality of rays of image light and can reduce its weight and improve the degree of freedom in design, and an image projection device.SOLUTION: An optical member has: a first reflecting surface (13); a second reflecting surface (14) arranged opposite to the first reflecting surface (13); a gap part (56) provided between the first reflecting surface (13) and the second reflecting surface (14); a first holding part (53) holding the first reflecting surface (13); a second holding part (54) holding the second reflecting surface (14); and connection parts (51) formed integrally with the first holding part (53) and second holding part (54) to connect them to each other.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an optical member and an image projection device, and more particularly to an optical member and an image projection device that project a projection image onto a display unit for displaying a virtual image. [Background technology]

[0002] Conventionally, dashboards that light up icons have been used as devices for displaying various types of information inside a vehicle. As the amount of information to be displayed increases, it has been proposed to embed an image display device in the dashboard or to configure the entire dashboard with an image display device.

[0003] However, since the instrument panel is located below the vehicle's windshield, the driver must move his or her eyes downward while driving in order to see the information displayed on the instrument panel, which is undesirable. Therefore, a head-up display (hereinafter referred to as HUD) has been proposed that projects an image onto the windshield so that the driver can read information when looking ahead of the vehicle (see, for example, Patent Documents 1 and 2).

[0004] In such a conventional image projection device, image light is projected from an image projection unit onto the windshield (display unit) of the vehicle, and the driver can visually recognize the image light reflected by the windshield superimposed on the background in front of the vehicle. It has also been proposed to project multiple image lights and form multiple virtual images at different distances from the windshield. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-119248 A [Patent Document 2] JP 2019-119262 A Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional image projection devices, multiple image lights irradiated from a liquid crystal display device or the like are split using optical elements, and the image positions of virtual images are made different depending on the difference in the paths of the split image lights. Although it is assumed that a reflecting prism or the like is used as an optical element for splitting the image light, a reflecting prism that is thickly molded has problems in terms of moldability and weight reduction. In addition, since the refractive index of the material constituting the reflecting prism is higher than that of air, there are restrictions in terms of the path difference of the light propagating inside the reflecting prism and the angle of the reflecting surface, and there is a problem of low design freedom. In particular, depending on the angle at which the image light is incident on the reflecting surface, aberration may occur in the projected virtual image, and there is also a problem of reduced visibility of the virtual image.

[0007] Therefore, the present invention has been made in consideration of the above-mentioned conventional problems, and aims to provide an optical component and an image projection device that can appropriately branch multiple image light beams, and that can achieve weight reduction and improved design freedom. [Means for solving the problem]

[0008] In order to solve the above problems, the optical element of the present invention is characterized in having a first reflecting surface, a second reflecting surface arranged opposite the first reflecting surface, a gap portion provided between the first reflecting surface and the second reflecting surface, a first holding portion that holds the first reflecting surface, a second holding portion that holds the second reflecting surface, and a connecting portion that is formed integrally with the first holding portion and the second holding portion and connects the two together.

[0009] In such an optical element of the present invention, the first holding portion holds the first reflective surface, the second holding portion holds the second reflective surface, and a connecting portion connecting the two is formed integrally, with a gap being provided between the first and second reflective surfaces, so that the distance and relative positional relationship between the first and second reflective surfaces is kept constant, multiple image light beams can be appropriately branched, and weight reduction and increased design freedom can be achieved.

[0010] In one aspect of the invention, the first holding portion and the second holding portion are made of a material that transmits light.

[0011] In one aspect of the invention, the first reflecting surface is a surface of the first holding portion, and the second reflecting surface is a surface of the second holding portion.

[0012] In one aspect of the present invention, the connecting portion is provided on a side of the first holding portion and the second holding portion.

[0013] In addition, in one aspect of the present invention, the connecting portion is provided on the light incident side of the first reflecting surface.

[0014] In addition, in one aspect of the invention, the connecting portion is provided on the light exit side of the second reflecting surface.

[0015] In addition, in one embodiment of the present invention, the first holding portion and the second holding portion are made of a material that blocks light, a first plane mirror is provided on the first holding portion, and a second plane mirror is provided on the second holding portion.

[0016] In order to solve the above-mentioned problems, the optical element of the present invention is an image projection device having any one of the optical elements described above and projecting image light onto a display unit for displaying a virtual image, comprising an image irradiating unit which irradiates the image light and a projection optical unit which irradiates the image light onto the display unit, wherein the image irradiating unit irradiates near image light from a near display area and far image light from a far display area, the far image light is reflected by the first reflecting surface and the second reflecting surface to reach the projection optical unit, and the near image light passes through the gap to reach the projection optical unit. Effect of the Invention

[0017] The present invention can provide an optical member and an image projection device that can appropriately split a plurality of image lights, and that can achieve a reduction in weight and an improvement in design freedom. [Brief description of the drawings]

[0018] [Figure 1] 2 is a schematic diagram illustrating projection of virtual images P1 and P2 using the image projection device 100 according to the first embodiment. FIG. [Diagram 2] 2 is a schematic diagram showing an example of the configuration of an image projection unit 10 in the first embodiment. FIG. [Diagram 3] 3A and 3B are schematic diagrams showing an example of the structure of a mirror holding part 50 in the first embodiment, where FIG. 3A is a schematic perspective view and FIG. 3B is a schematic cross-sectional view. [Figure 4] 5A to 5C are schematic cross-sectional views showing a method of forming the mirror holding member 50 in the first embodiment. [Diagram 5] 13 is a schematic perspective view showing a structural example of a mirror holding part 50 in a modified example of the first embodiment. FIG. [Figure 6] 6A and 6B are schematic diagrams showing an example of the structure of a mirror holding part 50 in the second embodiment, where FIG. 6A is an upper perspective view and FIG. 6B is a lower perspective view. [Figure 7] 7A to 7C are schematic cross-sectional views showing a method of forming a mirror holding member 50 in the second embodiment. [Figure 8] 8A and 8B are schematic diagrams showing an example of the structure of a mirror holding part 50 in the third embodiment, where FIG. 8A is an upper perspective view and FIG. 8B is a lower perspective view. [Figure 9] 9A and 9B are schematic diagrams showing an example of the structure of a mirror holding part 50 in the fourth embodiment, where FIG. 9A is an upper perspective view and FIG. 9B is a lower perspective view. [Figure 10] 10A and 10B are schematic diagrams showing an example of the structure of a mirror holding part 50 in the fifth embodiment, where FIG. 10A is an upper perspective view and FIG. 10B is a lower perspective view. [Figure 11] 11A and 11B are schematic diagrams showing an example of the structure of a mirror holding part 50 in the sixth embodiment, where FIG. 11A is an upper perspective view and FIG. 11B is a lower perspective view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] (First embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. FIG. 1 is a schematic diagram for explaining the projection of virtual images P1 and P2 using an image projection device 100 according to this embodiment. As shown in FIG. 1, the image projection device 100 includes an image irradiation unit 10, a primary mirror 20, and a secondary mirror 30. In FIG. 1, the direction perpendicular to the paper surface is the x-axis direction, the up-down direction is the y-axis direction, and the left-right direction is the z-axis direction. Here, the x-axis direction corresponds to the left-right direction (width direction) of the vehicle on which the image projection device 100 is mounted, the y-axis direction corresponds to the up-down direction (vertical direction), and the z-axis direction corresponds to the front-rear direction.

[0020] As shown in Fig. 1, image light projected from the image projection device 100 is reflected by a windshield (display unit) WS and irradiated to the driver's viewpoint. The driver visually recognizes virtual images P1 and P2 formed on an extension (in the direction of the dashed line) of the optical path along which the image light is incident. In this embodiment, an example is shown in which the image projection device 100 projects image display light to form two virtual images P1 and P2, but the number of virtual images is not limited.

[0021] In the image projection device 100 of this embodiment, the image projection unit 10 projects image light for far distances and image light for near distances, which are respectively formed as virtual images P1 and P2. The dashed line in FIG. 1 shows a path (reference light) of the center position of the image light for far distances, and the dashed line shows a path (reference light) of the center position of the image light for near distances. In general, the driver's line of sight and the viewpoint distance tend to change according to the traveling speed of the vehicle, and as the vehicle speed increases, the driver's line of sight and the viewpoint distance tend to move farther away. Therefore, the driver's line of sight movement can be reduced by displaying the image light for near distances in a low-speed range such as when the vehicle is traveling on a general road, and displaying the image light for far distances in a high-speed range such as when the vehicle is traveling on a highway. In addition, the information displayed by the far image and the near image may be switched. As an example, the far image projected by the image light for far distances may be auxiliary information related to driving, such as an image for calling attention or emergency information. Further, examples of near images projected using near image light include a speed and sound volume indicator, a traveling direction guide, and the like.

[0022] As shown in FIG. 1, the image light for far distances and the image light for near distances irradiated from the image irradiation unit 10 are reflected by the primary mirror 20, the secondary mirror 30, and the windshield WS to reach the viewpoint 40. At this time, the trajectory of the light reaching the viewpoint 40 from the direction in which the virtual images P1 and P2 are viewed is set as the reference ray. In other words, this reference ray can be considered to be substantially the same as the trajectory of the light irradiated from the center of the effective area from which the light is emitted in the image irradiation unit 10 when it reaches the viewpoint 40. The actual image light is irradiated from the image irradiation unit 10 with a predetermined area, and the light beam spreads from each position on the display surface, and is condensed or expanded by the optical power of the reflecting surfaces of the primary mirror 20 and the secondary mirror 30. Therefore, the reference ray shown in FIG. 1 does not indicate the path along which the irradiated light in the entire area of ​​the image irradiation unit 10 travels.

[0023] The image irradiation unit 10 is a part that irradiates image light containing image information by receiving a signal containing image information from an information processing unit (not shown). The image irradiation unit 10 will be described in detail later. The image light irradiated from the image irradiation unit 10 is incident on a primary mirror 20. The specific configuration of the image irradiation unit 10 is not limited, and a conventionally known device such as a liquid crystal display device, an organic EL display device, or a combination of a laser light source and an optical modulation element can be used. In the example shown in FIG. 1, a device that irradiates light from a light emitting diode (LED) from the rear side of the liquid crystal display device is used.

[0024] The primary mirror 20 is an optical member on which the image light irradiated from the image irradiation unit 10 is incident and which reflects it in the direction of the secondary mirror 30. In the example shown in FIG. 1, a free-form surface mirror with optical design necessary for projecting the image light as virtual images P1 and P2 is shown as the primary mirror 20. The reflective surface of the primary mirror 20 will be described in detail later, but it has a saddle shape that is concave in the y-axis direction (first direction) and convex in the x-axis direction (second direction). Therefore, the reflective surface of the primary mirror 20 gives the image light positive optical power in the height direction and negative optical power in the width direction. In addition, the reflective surface of the primary mirror 20 is set so that only the y-axis component forms an intermediate image before reaching the secondary mirror 30.

[0025] The secondary mirror 30 is an optical member that receives the image light reflected by the primary mirror 20 and reflects it in the direction of the windshield WS. In the example shown in FIG. 1, the secondary mirror 30 is a free-form mirror with a concave shape that is optically designed to project the image light as virtual images P1 and P2. The reflecting surface of the secondary mirror 30 has different focal lengths in the x-axis component and the y-axis component in the plane, and is set so that the x-axis component and the y-axis component of the irradiated light are imaged at the same position after being reflected by the secondary mirror 30. Here, the combination of the primary mirror 20 and the secondary mirror 30 constitutes a projection optical unit in the present invention in order to irradiate the near image light and the far image light to the windshield WS.

[0026] The windshield WS is provided in front of the driver's seat of the vehicle, and has a function as an optical member that reflects the image light incident from the secondary mirror 30 toward the viewpoint 40 on the inner surface of the vehicle and transmits light from outside the vehicle toward the viewpoint 40. Therefore, the windshield WS corresponds to the display unit in the present invention. Here, an example is shown in which the windshield WS is used as the display unit, but a combiner may be prepared as a display unit separately from the windshield WS and reflect the light from the secondary mirror 30 toward the viewpoint 40. In addition, the display unit is not limited to being located in front of the vehicle, and may be located to the side or rear as long as it projects an image toward the passenger's viewpoint 40.

[0027] The viewpoint 40 is the eye (eyebox) of the driver or passenger of the vehicle, and the driver or passenger visually recognizes the formed virtual images P1, P2 as the image light enters the eyebox and reaches the retina.

[0028] The virtual images P1 and P2 are displayed as if they were formed in space when the image light reflected by the windshield WS reaches the viewpoint (eyebox) 40 of the driver or the like. The positions at which the virtual images P1 and P2 are formed are determined by the spread angle of the light irradiated from the image irradiation unit 10 as it travels toward the viewpoint 40 after being reflected by the primary mirror 20 and the secondary mirror 30. At this time, the driver or passenger at the viewpoint 40 recognizes the virtual images P1 and P2 as if they exist at an imaging position farther away than the windshield WS.

[0029] Fig. 2 is a schematic diagram showing a configuration example of the image projection unit 10. As shown in Fig. 2, the image projection unit 10 includes a light source unit 11, an image display unit 12, a first plane mirror 13, a second plane mirror 14, and a mirror holding unit 50. The image display unit 12 includes a far display area 12a and a near display area 12b. The dashed arrow in Fig. 2 typically indicates the path (reference light ray) of the center position of the far image light L1, and the dashed arrow typically indicates the path (reference light ray) of the center position of the near image light L2.

[0030] The light source unit 11 is a part that irradiates the image display unit 12 with irradiation light. In the example shown in FIG. 2, the light source unit 11 is disposed on the rear side of the transmissive image display unit 12, and the irradiation light is transmitted through the image display unit 12, but a reflective image display unit 12 may be used to irradiate the irradiation light from the display surface side. The specific configuration of the light source unit 11 is not limited, and a light emitting diode (LED) or a laser light source may be used. In addition, when an organic EL display device is used as the image display unit 12, the light source unit 11 and the image display unit 12 are integrally configured.

[0031] The image display unit 12 is a part that displays a projected image based on image information from the control unit. The specific configuration of the image display unit 12 is not limited, and for example, a conventionally known device such as a liquid crystal display device, an organic EL display device, or a light modulation element can be used. In the example shown in FIG. 2, a liquid crystal display device is used as the image display unit 12. As will be described later, the image display unit 12 is configured to include a far display area 12a and a near display area 12b that display a near image and a far image, respectively. The far image displayed in the far display area 12a is irradiated as a far image light L1, and the near image displayed in the near display area 12b is irradiated as a near image light L2. Here, the far display area 12a and the near display area 12b may be configured by different display devices, but it is preferable to use one display device divided into two areas.

[0032] The first plane mirror 13 is an optical member having a flat reflecting surface. The reflecting surface of the first plane mirror 13 is disposed at a position where the distant image light L1 irradiated from the distant display area 12a is incident. The reflecting surface of the first plane mirror 13 is disposed at a predetermined angle with respect to the distant display area 12a, and reflects the incident distant image light L1 toward the second plane mirror 14. The first plane mirror 13 corresponds to the first reflecting surface in the present invention.

[0033] The second plane mirror 14 is an optical member having a flat reflecting surface and disposed opposite the first plane mirror 13. The reflecting surface of the second plane mirror 14 is disposed at a position where the distant image light L1 reflected by the first plane mirror 13 is incident. The reflecting surface of the second plane mirror 14 is disposed at an inclination at a predetermined angle with respect to the image display unit 12, and reflects the incident distant image light L1 toward the primary mirror 20. The second plane mirror 14 corresponds to the second reflecting surface in the present invention.

[0034] The mirror holding unit 50 is a member disposed on the light emission side of the image display unit 12 and holds the first plane mirror 13 and the second plane mirror 14. By holding the first plane mirror 13 and the second plane mirror 14 with the mirror holding unit 50, the relative positional relationship and distance between them can be maintained, and the reflection angle and optical distance of the distant image light L1 can be appropriately set. Although FIG. 2 shows the first plane mirror 13 and the second plane mirror 14 as self-supporting flat plate-like members, the first reflection surface and the second reflection surface may be formed on the surface of the mirror holding unit 50 by using a deposition technique or a plating technique. The mirror holding unit 50 will be described in detail later.

[0035] 2, the far-distance image light L1 irradiated from the far-distance display region 12a is incident on the first plane mirror 13, is reflected, and travels toward the second plane mirror 14. The far-distance image light L1 that reaches the second plane mirror 14 is reflected again and reaches the primary mirror 20. The first plane mirror 13 and the second plane mirror 14 are not disposed on the path of the near-distance image light L2 irradiated from the near-distance display region 12b. Therefore, the near-distance image light L2 irradiated from the near-distance display region 12b travels through the space between the first plane mirror 13 and the second plane mirror 14 to reach the primary mirror 20.

[0036] 2, the near image light L2 is directly irradiated to the primary mirror 20, whereas the far image light L1 is reflected by the first plane mirror 13 and the second plane mirror 14 and irradiated to the primary mirror 20. As a result, a difference in optical distance occurs between the near image light L2 and the far image light L1 until they reach the primary mirror 20, which is the distance W in the longitudinal direction of the image display unit 12. Furthermore, on the reflecting surface of the primary mirror 20, the far image light L1 and the near image light L2 reach different regions, and the paths of the far image light L1 and the near image light L2 reflected by the primary mirror 20 are also different. Due to this difference in optical distance and path, the distance and image formation position of the virtual images P1, P2 from the windshield WS differ.

[0037] When the far-distance image light L1 is propagated through a material with a refractive index n using a prism or the like, the difference in optical distance between the far-distance image light L1 and the near-distance image light L2 is nW, which is the product of the distance W and the refractive index n. Because the refractive index of the material constituting the prism is greater than 1, it is difficult to make the difference in optical distance between the far-distance image light L1 and the near-distance image light L2 smaller than nW.

[0038] It is possible to reduce the difference in optical distance to less than nW by adjusting the angle of the reflecting surface of the prism and reducing the distance between the two reflecting surfaces of the prism, but there is a limit to the angle of the reflecting surface for the distant image light L1 to reach the second plane mirror 14 from the first plane mirror 13, and the design freedom is low. In addition, aberration occurs depending on the incident angle of the distant image light L1 to the reflecting surface of the prism, making it difficult to improve the quality of the virtual image P1.

[0039] In the image projection device 100 of this embodiment, the far-field image light L1 propagates between the first plane mirror 13 and the second plane mirror 14 through air with a refractive index of 1. Therefore, the difference in optical distance between the far-field image light L1 and the near-field image light L2 is W, which is the product of the longitudinal distance W of the image display unit 12 and the refractive index 1. Therefore, when the first plane mirror 13 and the second plane mirror 14 are used, the difference in optical distance between the far-field image light L1 and the near-field image light L2 can be reduced to about W. In addition, by disposing the second plane mirror 14 at a position away from the image display unit 12 in the longitudinal direction, the difference in optical distance can be made larger than W. As a result, the image projection device 100 can appropriately branch a plurality of image lights, making it possible to reduce weight and improve design freedom.

[0040] FIG. 3 is a schematic diagram showing a structural example of the mirror holding part 50 in this embodiment, in which FIG. 3(a) is a schematic perspective view and FIG. 3(b) is a schematic cross-sectional view. As shown in FIG. 3(a), the mirror holding part 50 has an attachment surface part 51, a positioning hole 51a, side walls 52a and 52b, a first holding part 53, a second holding part 54, a notch part 55, and a gap part 56. Also, as shown in FIG. 3(b), the image display part 12 is provided with a mounting part 12c and a positioning pin 12d. The dashed arrow shown in FIG. 3 typically indicates the reference light beam of the far image light L1, and the dashed arrow typically indicates the reference light beam of the near image light L2.

[0041] The mirror holding part 50 is a member in which the mounting surface part 51, the side walls 52a and 52b, the first holding part 53 and the second holding part 54 are integrally formed. As shown in Fig. 3(b), the first plane mirror 13 and the second plane mirror 14 are provided on the opposing surfaces of the first holding part 53 and the second holding part 54, respectively. In the example shown in Fig. 3(b), the first plane mirror 13 and the second plane mirror 14 are bonded to the first holding part 53 and the second holding part 54, but the first reflection surface and the second reflection surface may be formed on the surfaces of the first holding part 53 and the second holding part 54, respectively, by using a deposition technique or a plating technique.

[0042] The material constituting the mirror holding part 50 is not limited, and resin, metal, etc. can be used. It is preferable to use a resin material from the viewpoint of moldability and weight reduction. In addition, as described later, since the far image light L1 and the near image light L2 pass through the gap part 56 to reach the primary mirror 20, in this embodiment, the mirror holding part 50 including the first holding part 53 and the second holding part 54 can also be made of a material that blocks light.

[0043] The mounting surface portion 51 is a portion formed integrally with the first holding portion 53 and the second holding portion 54, and holds the first holding portion 53 and the second holding portion 54 so that the interval and angle between them and the image display portion 12 are constant. In the example shown in FIG. 3, the mounting surface portion 51 is a plate-shaped portion extending along the arrangement direction of the first plane mirror 13 and the second plane mirror 14 on the side of the first plane mirror 13 and the second plane mirror 14. The mounting surface portion 51 is provided on the image display portion 12 side of the first plane mirror 13 and the second plane mirror 14, and has side walls 52a and 52b erected thereon. The mounting surface portion 51 is provided with a plurality of positioning holes 51a. The mounting surface portion 51 is a portion formed integrally with the first holding portion 53 and the second holding portion 54 to connect them, and corresponds to the connecting portion in the present invention.

[0044] The positioning holes 51a are holes provided penetrating the mounting surface portion 51. When the mounting surface portion 51 is mounted on the mounting portion 12c of the image display portion 12, positioning pins 12d provided on the mounting portion 12c are inserted into the positioning holes 51a. By inserting the positioning pins 12d into the positioning holes 51a, the mirror holding portion 50 is positioned at a predetermined position on the image display portion 12, and the first plane mirror 13 and the second plane mirror 14 are also positioned relative to the image display portion 12.

[0045] The side walls 52a and 52b are wall-like portions erected along the longitudinal direction of the mounting surface 51 in the width direction of the first holding portion 53 and the second holding portion 54. The side walls 52a and 52b are provided on both sides of the first holding portion 53 and the second holding portion 54, and are formed integrally with the mounting surface 51, the first holding portion 53, and the second holding portion 54. In the example shown in FIG. 3, the side walls 52a and 52b are separated by a notch 55 formed between them.

[0046] The first holding portion 53 is a plate-shaped portion provided between the side walls 52a and holds the first plane mirror 13. The first holding portion 53 is inclined at a predetermined angle with respect to the mounting surface portion 51, and is provided at a position facing the far display area 12a of the image display unit 12. The surface of the first holding portion 53 facing the far display area 12a is a reflective surface, and the first plane mirror 13 is provided thereon. In the example shown in FIG. 3, the first plane mirror 13 is formed separately from the mirror holding portion 50, and the first plane mirror 13 is bonded to the reflective surface of the first holding portion 53. However, the first reflective surface may be directly formed on the first holding portion 53 using a deposition technique or a plating technique. The first reflective surface may be formed by mirror-polishing the first holding portion 53.

[0047] The second holding portion 54 is a plate-shaped portion provided between the side walls 52b and holds the second plane mirror 14. The second holding portion 54 is disposed at a predetermined angle with respect to the mounting surface portion 51, and is provided at a position facing the first holding portion 53 in the longitudinal direction of the mounting surface portion 51. The first holding portion 53 and the second holding portion 54 may be parallel or non-parallel. The surface of the second holding portion 54 facing the first holding portion 53 is a reflective surface, and the second plane mirror 14 is provided on the surface. In the example shown in FIG. 3, the second plane mirror 14 is formed separately from the mirror holding portion 50, and the second plane mirror 14 is bonded to the reflective surface of the second holding portion 54. However, the second reflective surface may be directly formed on the second holding portion 54 using a deposition technique or a plating technique. The second holding portion 54 may be mirror-polished to form the second reflective surface.

[0048] The cutout portion 55 is a cutout formed between the side wall portions 52a, 52b, and separates the side wall portions 52a, 52b between the first holding portion 53 and the second holding portion 54. Although the example shown in Fig. 3 shows an example in which the cutout portion 55 is provided, the side wall portions 52a, 52b may be provided continuously along the mounting surface portion 51 without providing the cutout portion 55. By providing the cutout portion 55, a working space can be secured when bonding the first plane mirror 13 and the second plane mirror 14 to the first holding portion 53 and the second holding portion 54, thereby improving working efficiency.

[0049] The gap 56 is a space provided between the first holding part 53 and the second holding part 54. As shown in Figs. 3(a) and 3(b), the far image light L1 irradiated from the far display area 12a is reflected by the first plane mirror 13, and travels through the gap 56 along the longitudinal direction of the mounting surface part 51 to reach the second plane mirror 14. The near image light L2 irradiated from the near display area 12b travels through the gap 56 toward the primary mirror 20. As described in Fig. 2, the gap 56 is not provided with a resin material or glass material having a high refractive index, but is filled with air having a low refractive index. Here, an example is shown in which the gap 56 is open to the atmosphere and filled with air, but the mirror holding part 50 may be housed in an airtight container to make the gap 56 a vacuum state.

[0050] FIG. 4 is a schematic cross-sectional view showing a method for forming the mirror holding part 50 in this embodiment. FIG. 4 shows a cross section along the arrangement direction of the first holding part 53 and the second holding part 54, and other parts are omitted from the illustration. As shown in FIG. 4, when the mirror holding part 50 is made of a resin material, molds 61 and 62 are prepared and a conventionally known injection molding technique can be used. In the example shown in FIG. 4, the mold 61 is a cavity on the concave side, and the mold 62 is a core on the convex side. The joints of the molds 61 and 62 are parting lines PL1 to PL3, and by joining the molds 61 and 62 and injecting resin into the hollow parts, each part of the mirror holding part 50 can be integrally formed.

[0051] As described above, in the optical member and image projector 100 of this embodiment, the mounting surface portion 51 is formed integrally with the first holding portion 53 and the second holding portion 54 to connect them together, and a gap is provided between the first holding portion 53 and the second holding portion 54. This keeps the distance and relative positional relationship between the first plane mirror 13 and the second plane mirror 14 constant, allowing multiple image light beams to be appropriately branched, and enabling weight reduction and improved design freedom.

[0052] (Modification of the first embodiment) Next, a modified example of the first embodiment of the present invention will be described with reference to Fig. 5. Descriptions of contents that overlap with the first embodiment will be omitted. Fig. 5 is a schematic perspective view showing a structural example of a mirror holding part 50 in this modified example. This modified example differs from the first embodiment in that the side wall part 52 does not have a notch 55, and that the mounting surface part 51 is provided across the width direction on the bottom side of the first holding part 53.

[0053] As shown in FIG. 5, in this modification, the side wall portion 52 is continuously erected along the longitudinal direction of the mounting surface portion 51. The first holding portion 53 and the second holding portion 54 are provided between the continuous side wall portions 52. Therefore, the gap portion 56 is surrounded on all four sides by the first holding portion 53, the second holding portion 54, and the side wall portion 52. In this modification, since the mounting surface portion 51 and the side wall portion 52 are continuously provided in the longitudinal direction, the rigidity of the mirror holding portion 50 is increased to suppress deformation, and the distance and relative positional relationship between the first holding portion 53 and the second holding portion 54 can be kept constant. The mounting surface portion 51 and the side wall portion 52 are portions formed integrally with the first holding portion 53 and the second holding portion 54 to connect them, and correspond to the connecting portion in the present invention.

[0054] In the optical member and image projector 100 of this modified example, the mounting surface portion 51 and the side wall portion 52 are integrally formed with the first holding portion 53 and the second holding portion 54 to connect them together, and a gap portion 56 is provided between the first holding portion 53 and the second holding portion 54. This keeps the distance and relative positional relationship between the first plane mirror 13 and the second plane mirror 14 constant, allowing multiple image light beams to be appropriately branched, making it possible to reduce weight and improve design freedom.

[0055] Second embodiment Next, a second embodiment of the present invention will be described with reference to Figs. 6 and 7. Descriptions of contents overlapping with those of the first embodiment will be omitted. Fig. 6 is a schematic diagram showing a structural example of a mirror holding part 50 in this embodiment, Fig. 6(a) being an upper perspective view, and Fig. 6(b) being a lower perspective view. As shown in Figs. 6(a) and 6(b), the mirror holding part 50 has an attachment surface part 51, a positioning hole 51a, a side wall part 52, a first holding part 53, a second holding part 54, a notch part 55, a void part 56, and a top surface part 57. In this embodiment, the mirror holding part 50 including the first holding part 53, the second holding part 54, and the top surface part 57 is made of a material that transmits light.

[0056] The top surface 57 is a plate-like portion formed integrally with the side wall portion 52, the first holding portion 53, and the second holding portion 54, and provided on the light emission side of the second holding portion 54. Since the far image light L1 and the near image light L2 pass through the top surface 57, the mirror holding portion 50 is made of a material that transmits light. The top surface 57, the side wall portion 52, and the mounting surface portion 51 are portions formed integrally with the first holding portion 53 and the second holding portion 54 to connect them, and correspond to the connecting portion in the present invention. In this embodiment, the gap portion 56 is surrounded on all four sides by the side wall portion 52, the first holding portion 53, and the second holding portion 54, and further the top surface portion 57 is provided on the light emission side.

[0057] In this embodiment, the far image light L1 irradiated from the far display region 12a is reflected by the first plane mirror 13, travels through the gap 56 along the longitudinal direction of the mounting surface portion 51, is reflected by the second plane mirror 14, passes through the top surface portion 57, and travels toward the primary mirror 20. Meanwhile, the near image light L2 irradiated from the near display region 12b traverses the gap 56, passes through the top surface portion 57, and travels toward the primary mirror 20.

[0058] FIG. 7 is a schematic cross-sectional view showing a method for forming the mirror holding part 50 in this embodiment. FIG. 7 shows a cross section along the arrangement direction of the first holding part 53 and the second holding part 54, and other parts are omitted from the illustration. The mold 61 is a core on the convex side, and the mold 62 is a cavity on the concave side. FIG. 7(a) shows a case where the parting line PL3 is formed at the same height as the top surface part 57, and FIG. 7(b) shows a case where the parting line PL3 is formed on the bottom side like the parting line PL2. In this embodiment, too, the molds 61 and 62 are aligned and resin is injected into the hollow part, so that each part of the mirror holding part 50 can be integrally formed.

[0059] 7(a) and (b), the core mold 61 is provided with a shape corresponding to the gap 56, and the first holding portion 53 and the second holding portion 54 are inclined with respect to the parting lines PL2, PL3. In this embodiment, after the mirror holding portion 50 is molded by injecting a resin material into the molds 61 and 62, the mirror holding portion 50 can be removed in the inclined direction of the first holding portion 53 and the second holding portion 54.

[0060] In the optical member and image projector 100 of this embodiment, the top surface 57, the mounting surface 51, and the side wall 52 are also formed integrally with the first holding portion 53 and the second holding portion 54 to connect them together, and a gap 56 is provided between the first holding portion 53 and the second holding portion 54. This keeps the distance and relative positional relationship between the first plane mirror 13 and the second plane mirror 14 constant, allowing multiple image light beams to be appropriately branched, making it possible to reduce weight and improve design freedom.

[0061] Third embodiment Next, a third embodiment of the present invention will be described with reference to FIG. 8. Descriptions of contents overlapping with the first embodiment will be omitted. FIG. 8 is a schematic diagram showing a structural example of a mirror holding part 50 in this embodiment, in which FIG. 8(a) is an upper perspective view and FIG. 8(b) is a lower perspective view. As shown in FIGS. 8(a) and 8(b), the mirror holding part 50 has an attachment surface part 51, a positioning hole 51a, a first holding part 53, a second holding part 54, a gap part 56, a top surface part 57, a top surface extension part 58, and a positioning hole 58a. In this embodiment, the mirror holding part 50 including the first holding part 53, the second holding part 54, and the top surface part 57 is made of a material that transmits light.

[0062] In this embodiment, the mounting surface portion 51 is formed extending from the bottom of the first holding portion 53 in the arrangement direction of the first holding portion 53 and the second holding portion 54. The mounting surface portion 51 is not formed on the side of the first holding portion 53 and the second holding portion 54. The side wall portion 52 is formed on the side of the first holding portion 53 and the second holding portion 54 along the arrangement direction of both. The top surface extension portion 58 is a portion formed by extending the second holding portion 54 side of the top surface portion 57 in the arrangement direction of the first holding portion 53 and the second holding portion 54. The side wall portion 52 and the top surface portion 57 are portions formed integrally with the first holding portion 53 and the second holding portion 54 to connect them, and correspond to the connecting portion in the present invention.

[0063] In the optical member and image projector 100 of this embodiment, the top surface 57 and the side wall 52 are also formed integrally with the first holding portion 53 and the second holding portion 54 to connect them together, and a gap 56 is provided between the first holding portion 53 and the second holding portion 54. This keeps the distance and relative positional relationship between the first plane mirror 13 and the second plane mirror 14 constant, allowing multiple image light beams to be appropriately branched, making it possible to reduce weight and improve design freedom.

[0064] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. 9. Descriptions of contents overlapping with the first embodiment will be omitted. FIG. 9 is a schematic diagram showing a structural example of a mirror holding part 50 in this embodiment, in which FIG. 9(a) is an upper perspective view and FIG. 9(b) is a lower perspective view. As shown in FIGS. 9(a) and 9(b), the mirror holding part 50 has an attachment surface part 51, a positioning hole 51a, a first holding part 53, a second holding part 54, a gap part 56, and a bottom surface part 59. In this embodiment, the mirror holding part 50 including the first holding part 53, the second holding part 54, and the bottom surface part 59 is made of a material that transmits light.

[0065] The bottom surface portion 59 is a plate-like portion formed integrally with the side wall portion 52, the first holding portion 53, and the second holding portion 54, and provided on the light incident side of the first holding portion 53 and the second holding portion 54. Since the far image light L1 and the near image light L2 pass through the bottom surface portion 59, the mirror holding portion 50 is made of a material that transmits light. The bottom surface portion 59, the side wall portion 52, and the mounting surface portion 51 are portions formed integrally with the first holding portion 53 and the second holding portion 54 to connect them, and correspond to the connecting portion in the present invention. In this embodiment, the gap portion 56 is surrounded on all four sides by the side wall portion 52, the first holding portion 53, and the second holding portion 54, and further has a bottom surface portion 59 provided on the light incident side.

[0066] In this embodiment, the far image light L1 irradiated from the far display region 12a passes through the bottom surface portion 59 and is reflected by the first plane mirror 13, travels through the gap portion 56 along the longitudinal direction of the mounting surface portion 51, is reflected by the second plane mirror 14, and travels toward the primary mirror 20. Meanwhile, the near image light L2 irradiated from the near display region 12b passes through the bottom surface portion 59, traverses the gap portion 56, and travels toward the primary mirror 20.

[0067] In the optical member and image projector 100 of this embodiment, the bottom surface portion 59, the mounting surface portion 51, and the side wall portion 52 are also formed integrally with the first holding portion 53 and the second holding portion 54 to connect them together, and a gap portion 56 is provided between the first holding portion 53 and the second holding portion 54. This keeps the distance and relative positional relationship between the first plane mirror 13 and the second plane mirror 14 constant, allowing multiple image light beams to be appropriately branched, making it possible to reduce weight and improve design freedom.

[0068] Fifth embodiment Next, a fifth embodiment of the present invention will be described with reference to FIG. 10. Description of the contents overlapping with the first embodiment will be omitted. FIG. 10 is a schematic diagram showing a structural example of a mirror holding part 50 in this embodiment, in which FIG. 10(a) is an upper perspective view and FIG. 10(b) is a lower perspective view. As shown in FIGS. 10(a) and 10(b), the mirror holding part 50 has a mounting surface part 51, a positioning hole 51a, a side wall part 52, a first holding part 53, a second holding part 54, and a gap part 56. This embodiment is different from the first embodiment in that the mounting surface part 51 is formed only on the sides of the first holding part 53 and the second holding part 54, and the mounting surface part 51 is not formed across the width direction on the bottom side of the first holding part 53.

[0069] In the optical member and image projector 100 of this embodiment, the mounting surface portion 51 and the side wall portion 52 are also formed integrally with the first holding portion 53 and the second holding portion 54 to connect them together, and a gap portion 56 is provided between the first holding portion 53 and the second holding portion 54. This keeps the distance and relative positional relationship between the first plane mirror 13 and the second plane mirror 14 constant, allowing multiple image light beams to be appropriately branched, making it possible to reduce weight and improve design freedom.

[0070] Sixth embodiment Next, a sixth embodiment of the present invention will be described with reference to FIG. 11. The description of the contents overlapping with the first embodiment will be omitted. FIG. 11 is a schematic diagram showing a structural example of a mirror holding part 50 in this embodiment, FIG. 11(a) is an upper perspective view, and FIG. 11(b) is a lower perspective view. As shown in FIGS. 11(a) and 11(b), the mirror holding part 50 has a top surface part 57, a top surface extension part 58, a positioning hole 58a, a first holding part 53, a second holding part 54, and a gap part 56. The top surface part 57 is a part formed integrally with the first holding part 53 and the second holding part 54 to connect them, and corresponds to the connecting part in the present invention. FIG. 11 shows an example in which the top surface extension part 58 extends in the width direction of the first holding part 53 and the second holding part 54, but it may extend in the arrangement direction of the first holding part 53 and the second holding part 54 as in FIG. 8.

[0071] In the optical member and image projector 100 of this embodiment as well, the top surface portion 57 is integrally formed with the first holding portion 53 and the second holding portion 54 to connect them together, and a gap portion 56 is provided between the first holding portion 53 and the second holding portion 54. This keeps the distance and relative positional relationship between the first plane mirror 13 and the second plane mirror 14 constant, allowing multiple image light beams to be appropriately branched, making it possible to reduce weight and improve design freedom.

[0072] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0073] 100...Image projection device 10...Image irradiation unit 20…Primary mirror 30…Secondary mirror 40…Viewpoint 50…Mirror holder 11...Light source section 12...Image display section 12a…Far display area 12b…Near display area 12c...Mounting part 12d...Positioning pin 13…First flat mirror 14…Second plane mirror 51...Mounting surface 51a, 58a…Positioning hole 52,52a,52b...Side wall part 53...First holding part 54…Second holding part 55…Notch 56...Void part 57...Top section 58…Top extension 59…Bottom part 61,62…Mold

Claims

1. A first reflecting surface; a second reflecting surface disposed opposite the first reflecting surface; a gap provided between the first reflecting surface and the second reflecting surface; A first holding portion that holds the first reflecting surface; A second holding portion that holds the second reflecting surface; An optical member comprising: a connecting portion that is integrally formed with the first holding portion and the second holding portion and connects the first holding portion and the second holding portion.

2. The optical member according to claim 1 , An optical member, characterized in that the first holding portion and the second holding portion are made of a light-transmitting material.

3. 3. The optical member according to claim 2, the first reflecting surface is a surface of the first holding portion, The optical member, wherein the second reflecting surface is a surface of the second holding portion.

4. 3. The optical member according to claim 2, The optical member according to claim 1, wherein the connecting portion is provided on one side of the first holding portion and the second holding portion.

5. 3. The optical member according to claim 2, The optical member, wherein the connecting portion is provided on the light incident side of the first reflecting surface.

6. 3. The optical member according to claim 2, The optical member according to claim 1, wherein the connecting portion is provided on the light exit side of the second reflecting surface.

7. The optical member according to claim 1 , the first holding portion and the second holding portion are made of a material that blocks light, a first plane mirror is provided on the first holding portion; An optical member comprising: a second plane mirror provided on the second holding portion.

8. The optical member according to any one of claims 1 to 7, An image projection device that projects image light onto a display unit for displaying a virtual image, an image irradiating unit that irradiates the image light; a projection optical unit that irradiates the image light onto the display unit, the image irradiating unit irradiates near image light from a near display region and irradiates far image light from a far display region; the distant image light is reflected by the first reflecting surface and the second reflecting surface to reach the projection optical unit, The near image light passes through the gap and reaches the projection optical unit.

Images