Optical member and image projection device

Abstract

This optical member comprises: a first reflection surface (13); a second reflection surface (14) disposed so as to face the first reflection surface (13); a gap part (56) provided between the first reflection surface (13) and the second reflection surface (14); a first holding part (53) for holding the first reflection surface (13); a second holding part (54) for holding the second reflection surface (14); and a connection part (51) formed integrally with the first holding part (53) and the second holding part (54) and connecting both.

Description

Optical member and image projection device

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

[0002] Conventionally, dashboards that illuminate icons have been used to display various types of information inside vehicles. 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 windshield of the vehicle, the driver has to 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, which projects an image onto the windshield so that the driver can read the information when looking ahead of the vehicle (see, for example, Patent Documents 1 and 2).

[0004] In such a conventional image projection device, an 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.

[0005] Japanese Patent Publication No. 2019-119248 Japanese Patent Publication No. 2019-119262

[0006] Conventional image projection devices use optical elements to split multiple image light beams emitted from a liquid crystal display device or the like, and the positions of virtual images are varied depending on the path of the split image light beams. While a reflecting prism or the like can be used as an optical element to split the image light beams, splitting the image light beams from a large display area requires the prism to be thick, posing challenges in terms of formability and weight reduction. Furthermore, because the refractive index of the material composing the reflecting prism is higher than that of air, there are limitations on the path difference of light propagating within the reflecting prism and the angle of the reflecting surface, resulting in limited design flexibility. In particular, depending on the angle at which the image light beams are incident on the reflecting surface, aberrations may occur in the projected virtual image, reducing the visibility of the virtual image.

[0007] Furthermore, conventional image projection devices reflect image light using a free-form mirror and a windshield WS to form a virtual image in space, which causes aberrations that cause the paths of the image light incident on the left and right eyes to shift, resulting in vertical and horizontal parallax and reducing the visibility of the virtual image.

[0008] An object of the present disclosure is to provide an optical member and an image projection device that can appropriately split a plurality of image lights, and that can achieve weight reduction and improved design freedom.

[0009] An object of the present disclosure is to provide an image projection device that can improve the accuracy of aberration correction and thereby improve the visibility of a formed virtual image.

[0010] An object of the present disclosure is to provide an optical member and an image projection device that can be made lighter and have greater design freedom.

[0011] In order to solve the above problem, the optical element of the present disclosure has 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 them together.

[0012] In such an optical element disclosed herein, the first holding portion holds the first reflecting surface, the second holding portion holds the second reflecting surface, and a connecting portion connecting the two is formed integrally, and a gap portion is provided between the first reflecting surface and the second reflecting surface, thereby keeping the distance and relative positional relationship between the first reflecting surface and the second reflecting surface constant and allowing multiple image light beams to be appropriately branched, thereby enabling weight reduction and improved design freedom.

[0013] In order to solve the above problem, the image projection device of the present disclosure is an image projection device that projects image light onto a display unit for displaying a virtual image, and includes an image irradiation unit that irradiates the image light and a projection optical unit that irradiates the image light onto the display unit, the image irradiation unit having the above-mentioned optical element, the image irradiation unit irradiating near image light from a near display area and irradiating far image light from a far display area, the far image light being reflected by the first reflecting surface and the second reflecting surface to reach the projection optical unit, and the near image light passing through the void portion to reach the projection optical unit.

[0014] In order to solve the above problem, the image projection device of the present disclosure is an image projection device that projects image light onto a display unit for displaying a virtual image, and includes an image irradiation unit that irradiates the image light, a primary mirror that reflects the image light incident from the image irradiation unit, and a secondary mirror that reflects the image light incident from the primary mirror, and the reflective surface of the primary mirror has a saddle shape that is concave in a first direction and convex in a second direction.

[0015] In the image projection device of the present disclosure, the reflective surface of the primary mirror is saddle-shaped, concave in a first direction and convex in a second direction, and the image light reflected by the primary mirror is reflected by the secondary mirror, thereby improving the accuracy of aberration correction and improving the visibility of the virtual image that is formed.

[0016] In order to solve the above problem, the image projection device of the present disclosure is an image projection device that projects image light onto a display unit for displaying a virtual image, and includes an image display unit that irradiates near image light from a near display area and far image light from a far display area, a first plane mirror that reflects the far image light, a second plane mirror that reflects the far image light reflected by the first plane mirror, and a projection optical unit that irradiates the near image light incident from the near display area and the far image light incident from the second plane mirror onto the display unit.

[0017] In the image projection device of the present disclosure, the image light for distance irradiated from the distance display area is reflected by the first plane mirror and the second plane mirror, the image light for near distance is irradiated from the near display area, and the image light for distance and the image light for near distance are irradiated from the projection optical unit to the display unit, thereby making it possible to appropriately branch multiple image lights, thereby achieving weight reduction and improving design freedom.

[0018] In order to solve the above problems, the optical element of the present disclosure has a first portion made of a light-transmitting material and having a first reflecting surface, a second portion arranged opposite the first portion and made of the light-transmitting material and having a second reflecting surface, a connecting portion formed integrally with the first portion and the second portion and connecting them, and a gap portion provided between the first portion and the second portion and through which at least a portion of the light passes.

[0019] In such an optical element of the present disclosure, the first part, the second part, and the connecting part are integrally constructed from a light-transmitting material, and a gap is provided between the first part and the second part, thereby making it possible to reduce weight and improve design freedom.

[0020] In order to solve the above problem, the image projection device of the present disclosure is an image projection device that projects image light onto a display unit for displaying a virtual image, and is equipped with the above optical element, an image irradiation unit that irradiates the image light, and a projection optical unit that irradiates the image light onto the display unit, wherein the image irradiation 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 void portion to reach the projection optical unit.

[0021] The present disclosure can provide an optical member and an image projection device that can appropriately split a plurality of image lights, and that can achieve weight reduction and improved design freedom.

[0022] The present disclosure can provide an image projection device that can improve the accuracy of aberration correction and improve the visibility of the formed virtual image.

[0023] The present disclosure can provide an optical member and an image projection device that can achieve weight reduction and improved design freedom.

[0024] FIG. 1 is a schematic diagram illustrating projection of a virtual image using an image projection device according to the first embodiment. FIG. 2 is a schematic diagram illustrating a configuration example of an image projection unit according to the first embodiment. FIG. 3 is a schematic perspective view illustrating a structural example of a mirror holder according to the first embodiment. FIG. 4 is a schematic cross-sectional view illustrating a structural example of a mirror holder according to the first embodiment. FIG. 5 is a schematic cross-sectional view illustrating a method of forming a mirror holder according to the first embodiment. FIG. 6 is a schematic perspective view illustrating a structural example of a mirror holder according to a modified example of the first embodiment. FIG. 7 is a schematic perspective view illustrating a structural example of a mirror holder according to a modified example of the first embodiment. FIG. 8 is a schematic top perspective view illustrating a structural example of a mirror holder according to a second embodiment. FIG. 9 is a schematic bottom perspective view illustrating a structural example of a mirror holder according to the second embodiment. FIG. 10 is a schematic cross-sectional view illustrating a method of forming a mirror holder according to the second embodiment. FIG. 11 is a schematic top perspective view illustrating a structural example of a mirror holder according to a third embodiment. FIG. 12 is a schematic bottom perspective view illustrating a structural example of a mirror holder according to the third embodiment. FIG. 13 is a schematic top perspective view illustrating a structural example of a mirror holder according to a fourth embodiment. FIG. 14 is a schematic bottom perspective view illustrating a structural example of a mirror holder according to the fourth embodiment. FIG. 15 is a schematic top perspective view illustrating a structural example of a mirror holder according to a fifth embodiment. 10 is a schematic bottom perspective view illustrating a structural example of a mirror holding unit in a fifth embodiment. FIG. 11 is a schematic top perspective view illustrating a structural example of a mirror holding unit in a sixth embodiment. FIG. 12 is a schematic bottom perspective view illustrating a structural example of a mirror holding unit 50 in a sixth embodiment. FIG. 13 is a schematic perspective view illustrating the structure of a primary mirror in a seventh embodiment. FIG. 14 is a schematic horizontal cross-sectional view illustrating the structure of a primary mirror in a seventh embodiment. FIG. 15 is a schematic vertical cross-sectional view illustrating the structure of a primary mirror in a seventh embodiment. FIG. 16 is a schematic diagram illustrating a structural example of an image projection unit in a seventh embodiment. FIG. 17 is a schematic side view illustrating the positional relationship between the image projection unit, primary mirror, and secondary mirror, and the path of image light in a seventh embodiment. FIG. 18 is a schematic top view illustrating the positional relationship between the image projection unit, primary mirror, and secondary mirror, and the path of image light in a seventh embodiment. FIG. 19 is a schematic diagram illustrating parallax caused by aberration, showing left-right parallax. FIG. 19 is a schematic diagram illustrating parallax caused by aberration, showing up-down parallax. FIG. 19 is a schematic diagram illustrating a structural example of an image projection unit in a ninth embodiment.13. A schematic perspective view illustrating paths of far-distance image light L1 and near-distance image light L2 irradiated from an image irradiator in a ninth embodiment. A schematic view illustrating angles between a first plane mirror and a second plane mirror in an image irradiator in a ninth embodiment. A schematic view illustrating a configuration example of an image irradiator and angles between the first plane mirror and the second plane mirror in a tenth embodiment. A schematic view illustrating projection of a virtual image using an image projection device in an eleventh embodiment. A schematic cross-sectional view illustrating an overview of an image projection device in an eleventh embodiment. A schematic cross-sectional view illustrating a configuration example of an optical member in an eleventh embodiment. A schematic perspective view illustrating a configuration example of an optical member in an eleventh embodiment. A schematic cross-sectional view illustrating a configuration example of an optical member in a twelfth embodiment. A schematic cross-sectional view illustrating a configuration example of an optical member in a thirteenth embodiment. A schematic cross-sectional view illustrating a configuration example of an optical member in a fourteenth embodiment. A schematic cross-sectional view illustrating a configuration example of an optical member in a fifteenth embodiment.

[0025] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate.

[0026] First Embodiment Fig. 1 is a schematic diagram illustrating 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 projection unit 10, a primary mirror 20, and a secondary mirror 30. In Fig. 1, the direction perpendicular to the paper surface is defined as the x-axis direction, the up-down direction as the y-axis direction, and the left-right direction as 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.

[0027] 1, image light projected from the image projection device 100 is reflected by the windshield (display unit) WS and irradiated onto 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 entered. 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.

[0028] In the image projection device 100 of this embodiment, far-distance image light and near-distance image light are irradiated from the image irradiation unit 10, and are respectively formed as virtual images P1 and P2. The dashed line in FIG. 1 schematically indicates the path (reference ray) of the center position of the far-distance image light, and the dashed-dotted line schematically indicates the path (reference ray) of the center position of the near-distance image light. Generally, the driver's line of sight and viewpoint distance tend to change depending on the vehicle's traveling speed. As the vehicle speed increases, the driver's line of sight and viewpoint distance tend to move farther away. Therefore, by displaying near-distance image light at low speeds, such as when the vehicle is traveling on an ordinary road, and displaying far-distance image light at high speeds, such as when traveling on a highway, the driver's line of sight movement can be reduced. Furthermore, the information displayed between the far-distance image and the near-distance image may be switched. As an example, a far-distance image projected using far-distance image light may include auxiliary information related to driving, such as a warning image or emergency information. Further, examples of near images projected using near image light include speed and volume indicators, and travel direction guides.

[0029] As shown in FIG. 1 , the far-distance image light and near-distance image light irradiated from the image irradiator 10 are reflected by the primary mirror 20, the secondary mirror 30, and the windshield WS to reach the viewpoint 40. The trajectory of light reaching the viewpoint 40 from the direction in which the virtual images P1 and P2 are viewed is defined as a reference ray. In other words, this reference ray can be considered to be substantially the same as the trajectory of light irradiated from the center of the effective area from which light is emitted in the image irradiator 10 when it reaches the viewpoint 40. Actual image light is irradiated over a predetermined area from the image irradiator 10, and the light beam spreads from each position on the display surface. This light is then focused 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 represent the path of the irradiated light throughout the entire area of ​​the image irradiator 10.

[0030] The image irradiation unit 10 is a part that irradiates image light containing image information in response to a signal containing image information being supplied from an information processing unit (not shown). Details of the image irradiation unit 10 will be described later. The image light irradiated from the image irradiation unit 10 is incident on the 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 a light 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.

[0031] The primary mirror 20 is an optical component onto which the image light irradiated from the image projection unit 10 is incident and which reflects it toward the secondary mirror 30. In the example shown in FIG. 1 , the primary mirror 20 is a free-form mirror with the optical design necessary for projecting the image light as virtual images P1 and P2. The reflective surface of the primary mirror 20, which will be described in detail later, has a saddle-shaped configuration that is concave in the y-axis direction (short side direction, which is the height direction; first direction) and convex in the x-axis direction (long side direction, which is the width direction; second direction). Therefore, the reflective surface of the primary mirror 20 imparts positive optical power to the image light in the height direction and negative optical power in the width direction. Furthermore, the reflective surface of the primary mirror 20 is configured so that only the y-axis component forms an intermediate image before reaching the secondary mirror 30.

[0032] The secondary mirror 30 is an optical component that receives the image light reflected by the primary mirror 20 and reflects it toward the windshield WS. In the example shown in FIG. 1 , the secondary mirror 30 is a free-form mirror with a concave shape optically designed to project the image light as virtual images P1 and P2. The reflective surface of the secondary mirror 30 has different focal lengths for the x-axis component and the y-axis component in the plane, and is configured so that the x-axis component and the y-axis component of the irradiated light are imaged at the same position after reflection 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 disclosure, because it irradiates the near image light and the far image light onto the windshield WS.

[0033] The windshield WS is provided in front of the driver's seat of the vehicle, and functions as an optical element on the inside surface of the vehicle that reflects image light incident from the secondary mirror 30 toward the viewpoint 40 and transmits light from outside the vehicle toward the viewpoint 40. Therefore, the windshield WS corresponds to the display unit in this disclosure. While an example in which the windshield WS is used as the display unit has been shown here, a combiner may be provided as a display unit separate from the windshield WS and reflect light from the secondary mirror 30 toward the viewpoint 40. Furthermore, the display unit is not limited to being located at the 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.

[0034] The viewpoint 40 is the eye (eyebox) of the driver or passenger of the vehicle, and the image light enters the eyebox and reaches the retina, allowing the driver or passenger to view the formed virtual images P1 and P2.

[0035] 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 projection 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 perceives the virtual images P1 and P2 as being at image positions farther away than the windshield WS.

[0036] Fig. 2 is a schematic diagram showing an example configuration 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 also includes a far display area 12a and a near display area 12b. The dashed arrows in Fig. 2 schematically indicate the path (reference ray) of the center position of the far image light L1, and the dashed-dotted arrows schematically indicate the path (reference ray) of the center position of the near image light L2.

[0037] 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 passes through the image display unit 12. However, a reflective image display unit 12 may be used, and the irradiation light may be emitted from the display surface side. The specific configuration of the light source unit 11 is not limited, and a light-emitting diode or a laser light source may be used. Furthermore, 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.

[0038] The image display unit 12 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 conventionally known devices such as a liquid crystal display device, an organic EL display device, and 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 includes 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 far image light L1, and the near image displayed in the near display area 12b is irradiated as near image light L2. The far display area 12a and the near display area 12b may be configured by separate display devices, but it is preferable to use a single display device divided into two areas.

[0039] 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 far image light L1 emitted from the far display area 12a is incident. The reflecting surface of the first plane mirror 13 is disposed at an angle relative to the far display area 12a, and reflects the incident far image light L1 toward the second plane mirror 14. The first plane mirror 13 corresponds to the first reflecting surface in this disclosure.

[0040] 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 far-distance 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 angle at a predetermined angle with respect to the image display unit 12, and reflects the incident far-distance image light L1 toward the primary mirror 20. The second plane mirror 14 corresponds to the second reflecting surface in this disclosure.

[0041] The mirror holding unit 50 is a member disposed on the light output 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 are maintained, and the reflection angle and optical distance of the far-distance image light L1 can be appropriately set. While FIG. 2 shows the first plane mirror 13 and the second plane mirror 14 as self-supporting flat plate-like members, the first and second reflecting surfaces may be formed on the surface of the mirror holding unit 50 using vapor deposition or plating techniques. Details of the mirror holding unit 50 will be described later.

[0042] 2 , the far image light L1 emitted from the far display region 12a is incident on the first plane mirror 13, reflected, and travels toward the second plane mirror 14. The far image light L1 that reaches the second plane mirror 14 is reflected again and reaches the primary mirror 20. Furthermore, the first plane mirror 13 and the second plane mirror 14 are not disposed on the path of the near image light L2 emitted from the near display region 12b. Therefore, the near image light L2 emitted from the near display region 12b travels through the space between the first plane mirror 13 and the second plane mirror 14 and reaches the primary mirror 20.

[0043] 2 , the near image light L2 is directly irradiated onto 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 then irradiated onto 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 reflective 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 also differ. Due to this difference in optical distance and path, the distances and image positions of the virtual images P1, P2 from the windshield WS differ.

[0044] When the far 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 image light L1 and the near 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 that makes up the prism is greater than 1, it is difficult to make the difference in optical distance between the far image light L1 and the near image light L2 smaller than nW.

[0045] 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 far image light L1 to reach the second plane mirror 14 from the first plane mirror 13, and the degree of freedom in design is low. In addition, aberration occurs depending on the angle of incidence of the far image light L1 on the reflecting surface of the prism, making it difficult to improve the quality of the virtual image P1.

[0046] In the image projection device 100 of this embodiment, the far-distance image light L1 propagates between the first plane mirror 13 and the second plane mirror 14 through air, which has a refractive index of 1. Therefore, the difference in optical distance between the far-distance image light L1 and the near-distance 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-distance image light L1 and the near-distance image light L2 can be reduced to approximately W. Furthermore, by arranging the second plane mirror 14 at a position spaced apart from the image display unit 12 in the longitudinal direction, the difference in optical distance can be made larger than W. This allows the image projection device 100 to appropriately branch multiple image lights, thereby enabling weight reduction and increased design flexibility.

[0047] FIG. 3A is a schematic perspective view showing an example of the structure of the mirror holding unit 50 in this embodiment. FIG. 3B is a schematic cross-sectional view showing an example of the structure of the mirror holding unit 50 in this embodiment. As shown in FIG. 3A, the mirror holding unit 50 has an attachment surface portion 51, a positioning hole 51a, side wall portions 52a and 52b, a first holding portion 53, a second holding portion 54, a notch portion 55, and a gap portion 56. Also, as shown in FIG. 3B, the image display unit 12 is provided with a mounting portion 12c and a positioning pin 12d. The dashed arrows in FIGS. 3A and 3B schematically indicate reference rays of the far-distance image light L1, and the dashed-dotted arrows schematically indicate reference rays of the near-distance image light L2.

[0048] The mirror holding unit 50 is a member in which an attachment surface 51, side walls 52a and 52b, a first holding unit 53, and a second holding unit 54 are integrally formed. As shown in Fig. 3B , a first plane mirror 13 and a second plane mirror 14 are provided on opposing surfaces of the first holding unit 53 and the second holding unit 54, respectively. In the example shown in Fig. 3B , the first plane mirror 13 and the second plane mirror 14 are bonded to the first holding unit 53 and the second holding unit 54, but a first reflecting surface and a second reflecting surface may be formed on the surfaces of the first holding unit 53 and the second holding unit 54, respectively, using vapor deposition or plating technology.

[0049] The material constituting the mirror holding unit 50 is not limited, and resin, metal, etc. can be used. From the viewpoint of moldability and weight reduction, it is preferable to use a resin material. Furthermore, as will be described later, since the far image light L1 and the near image light L2 pass through the gap 56 to reach the primary mirror 20, in this embodiment, the mirror holding unit 50 including the first holding unit 53 and the second holding unit 54 can also be made of a material that blocks light.

[0050] 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 distance and angle between them and the image display unit 12 are constant. In the example shown in FIGS. 3A and 3B , 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 closer to the image display unit 12 than the first plane mirror 13 and the second plane mirror 14, and has side wall portions 52 a, 52 b erected thereon. The mounting surface portion 51 also has a plurality of positioning holes 51 a. 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 this disclosure.

[0051] The positioning holes 51a are holes provided through the mounting surface 51. When the mounting surface 51 is mounted on the mounting portion 12c of the image display unit 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 unit 50 is positioned at a predetermined position on the image display unit 12, and the first plane mirror 13 and the second plane mirror 14 are also positioned relative to the image display unit 12.

[0052] The side walls 52a and 52b are wall-like portions that stand upright 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 Figures 3A and 3B, the side walls 52a and 52b are separated by a notch 55 formed between them.

[0053] The first holding portion 53 is a plate-shaped portion provided between the sidewall portions 52a and configured to hold the first plane mirror 13. The first holding portion 53 is inclined at a predetermined angle relative to the mounting surface portion 51 and is positioned 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 on which the first plane mirror 13 is provided. In the example shown in FIGS. 3A and 3B , the first plane mirror 13 is formed separately from the mirror holding portion 50 and bonded to the reflective surface of the first holding portion 53. However, the first reflective surface may be formed directly on the first holding portion 53 using vapor deposition or plating techniques. Alternatively, the first reflective surface may be formed by mirror-polishing the first holding portion 53.

[0054] The second holding portion 54 is a plate-shaped portion provided between the sidewall portions 52b and holding the second plane mirror 14. The second holding portion 54 is inclined at a predetermined angle relative 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 reflective surface. In the example shown in FIGS. 3A and 3B , the second plane mirror 14 is formed separately from the mirror holding portion 50 and 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 vapor deposition or plating. Alternatively, the second reflective surface may be formed by mirror-polishing the second holding portion 54.

[0055] The cutout 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 Figures 3A and 3B shows an example in which the cutout 55 is provided, the side wall portions 52a, 52b may be provided continuously along the mounting surface portion 51 without providing the cutout 55. By providing the cutout 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.

[0056] The gap 56 is a space provided between the first holding unit 53 and the second holding unit 54. As shown in FIGS. 3A and 3B , the far-distance image light L1 emitted from the far-distance display region 12a is reflected by the first plane mirror 13 and travels through the gap 56 along the longitudinal direction of the mounting surface 51 to reach the second plane mirror 14. The near-distance image light L2 emitted from the near-distance display region 12b travels longitudinally through the gap 56 toward the primary mirror 20. As described with reference to FIG. 2 , the gap 56 is not filled with a resin material or glass material with a high refractive index, but is filled with air with a low refractive index. While the example shown here is one in which the gap 56 is open to the atmosphere and filled with air, the mirror holding unit 50 may be housed in a sealed container to create a vacuum in the gap 56.

[0057] FIG. 4 is a schematic cross-sectional view showing a method for forming the mirror holder 50 in this embodiment. FIG. 4 shows a cross section along the arrangement direction of the first holder 53 and the second holder 54, and other parts are omitted from the illustration. When the mirror holder 50 is made of a resin material, as shown in FIG. 4 , molds 61 and 62 are prepared, and a conventionally known injection molding technique can be used. In the example shown in FIG. 4 , mold 61 is a concave cavity, and mold 62 is a convex core. The molds 61 and 62 are joined at parting lines PL1 to PL3. By bringing the molds 61 and 62 together and injecting resin into the hollow portions, the various parts of the mirror holder 50 can be integrally formed.

[0058] As described above, in the optical member and image projection device 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 increased design freedom.

[0059] (Modification of First Embodiment) Next, a modification of the first embodiment of the present disclosure will be described with reference to Figures 5A and 5B. Description of content that overlaps with the first embodiment will be omitted. Figures 5A and 5B are schematic perspective views showing an example structure of the mirror holding unit 50 in this modification. This modification differs from the first embodiment in that the side wall 52 does not have the notch 55 and that the mounting surface 51 is provided across the width direction on the bottom side of the first holding unit 53.

[0060] As shown in FIGS. 5A and 5B , in this modification, the side wall portion 52 is provided continuously 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 portions 52. In this modification, the mounting surface portion 51 and the side wall portions 52 are provided continuously in the longitudinal direction, which increases the rigidity of the mirror holding portion 50, suppresses deformation, and maintains a constant distance and relative positional relationship between the first holding portion 53 and the second holding portion 54. The mounting surface portion 51 and the side wall portions 52 are integrally formed with the first holding portion 53 and the second holding portion 54, connecting them together, and correspond to the connecting portion in this disclosure.

[0061] In the optical member and image projection device 100 of this modified example, the mounting surface portion 51 and the side wall portion 52 are 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, and enabling weight reduction and increased design freedom.

[0062] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to FIGS. 6A and 6B and FIGS. 7A and 7B. Description of content overlapping with the first embodiment will be omitted. FIG. 6A is a schematic top perspective view showing an example structure of a mirror holder 50 in this embodiment, and FIG. 6B is a schematic bottom perspective view showing an example structure of the mirror holder 50 in this embodiment. As shown in FIGS. 6A and 6B , the mirror holder 50 has an attachment surface portion 51, a positioning hole 51a, a side wall portion 52, a first holder portion 53, a second holder portion 54, a notch portion 55, a gap portion 56, and a top surface portion 57. In this embodiment, the mirror holder 50, including the first holder portion 53, the second holder portion 54, and the top surface portion 57, is made of a light-transmitting material.

[0063] The top surface 57 is a plate-like portion that is formed integrally with the side wall 52, the first holding portion 53, and the second holding portion 54 and is provided on the light-emitting side of the second holding portion 54. Because 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 light-transmitting material. The top surface 57, the side wall 52, and the mounting surface 51 are formed integrally with the first holding portion 53 and the second holding portion 54 and connect them together, and correspond to the connecting portion in the present disclosure. In this embodiment, the gap 56 is surrounded on all four sides by the side wall 52, the first holding portion 53, and the second holding portion 54, and the top surface 57 is further provided on the light-emitting side.

[0064] 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 51, is reflected by the second plane mirror 14, passes through the top surface 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 57, and travels toward the primary mirror 20.

[0065] 7A and 7B are schematic cross-sectional views showing a method for forming the mirror holder 50 in this embodiment. FIGS. 7A and 7B show cross sections along the arrangement direction of the first holder 53 and the second holder 54, with other parts omitted from the illustration. Mold 61 is a convex core, and mold 62 is a concave cavity. FIG. 7A shows a case where parting line PL3 is formed at the same height as top surface 57, while FIG. 7B shows a case where parting line PL3 is formed on the bottom side, similar to parting line PL2. In this embodiment, too, the various parts of the mirror holder 50 can be integrally formed by joining molds 61 and 62 together and injecting resin into the hollow portions.

[0066] 7A and 7B, 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.

[0067] In the optical member and image projection device 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, and enabling weight reduction and increased design freedom.

[0068] Third Embodiment Next, a third embodiment of the present disclosure will be described with reference to FIGS. 8A and 8B . Description of content overlapping with the first embodiment will be omitted. FIG. 8A is a schematic top perspective view showing an example structure of a mirror holder 50 in this embodiment, and FIG. 8B is a schematic bottom perspective view showing an example structure of the mirror holder 50 in this embodiment. As shown in FIGS. 8A and 8B , the mirror holder 50 has an attachment surface portion 51, a positioning hole 51 a, a first holder portion 53, a second holder portion 54, a gap portion 56, a top surface portion 57, a top surface extension portion 58, and a positioning hole 58 a. In this embodiment, the mirror holder 50, including the first holder portion 53, the second holder portion 54, and the top surface portion 57, is made of a light-transmitting material.

[0069] In this embodiment, the mounting surface portion 51 is formed extending from the bottom of the first retaining portion 53 in the arrangement direction of the first retaining portion 53 and the second retaining portion 54. The mounting surface portion 51 is not formed on the sides of the first retaining portion 53 and the second retaining portion 54. The side wall portion 52 is formed on the sides of the first retaining portion 53 and the second retaining portion 54 along the arrangement direction of the first retaining portion 53 and the second retaining portion 54. The top surface extension portion 58 is a portion formed on the second retaining portion 54 side of the top surface portion 57 by extending in the arrangement direction of the first retaining portion 53 and the second retaining portion 54. The side wall portion 52 and the top surface portion 57 are formed integrally with the first retaining portion 53 and the second retaining portion 54 and connect the first retaining portion 53 and the second retaining portion 54, and correspond to the connecting portion in this disclosure.

[0070] In the optical member and image projection device 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, and enabling weight reduction and increased design freedom.

[0071] Fourth Embodiment Next, a fourth embodiment of the present disclosure will be described with reference to FIGS. 9A and 9B . Description of content overlapping with the first embodiment will be omitted. FIG. 9A is a schematic top perspective view showing an example structure of a mirror holder 50 in this embodiment, and FIG. 9B is a schematic bottom perspective view showing an example structure of the mirror holder 50 in this embodiment. As shown in FIGS. 9A and 9B , the mirror holder 50 has an attachment surface portion 51, a positioning hole 51 a, a first holder portion 53, a second holder portion 54, a gap portion 56, and a bottom surface portion 59. In this embodiment, the mirror holder 50, including the first holder portion 53, the second holder portion 54, and the bottom surface portion 59, is made of a light-transmitting material.

[0072] The bottom surface portion 59 is formed integrally with the side wall portion 52, the first holding portion 53, and the second holding portion 54, and is a plate-like portion provided on the light incident side of the first holding portion 53 and the second holding portion 54. Because 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 light-transmitting material. The bottom surface portion 59, the side wall portion 52, and the mounting surface portion 51 are formed integrally with the first holding portion 53 and the second holding portion 54 and connect the two, and correspond to the connecting portion in the present disclosure. 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 on the light incident side.

[0073] In this embodiment, the far image light L1 irradiated from the far display region 12a passes through the bottom surface 59 and is reflected by the first plane mirror 13, travels through the gap 56 along the longitudinal direction of the mounting surface 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 59 and travels longitudinally through the gap 56, and travels toward the primary mirror 20.

[0074] In the optical member and image projection device 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, and enabling weight reduction and increased design freedom.

[0075] Fifth Embodiment Next, a fifth embodiment of the present disclosure will be described with reference to FIGS. 10A and 10B . Description of content overlapping with the first embodiment will be omitted. FIG. 10A is a schematic top perspective view illustrating an example structure of a mirror holder 50 in this embodiment, and FIG. 10B is a schematic bottom perspective view illustrating an example structure of the mirror holder 50 in this embodiment. As shown in FIGS. 10A and 10B , the mirror holder 50 has a mounting surface 51, a positioning hole 51 a, a sidewall 52, a first holder 53, a second holder 54, and a gap 56. This embodiment differs from the first embodiment in that the mounting surface 51 is formed only on the sides of the first holder 53 and the second holder 54, and is not formed across the width of the bottom of the first holder 53.

[0076] In the optical member and image projection device 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, and enabling weight reduction and increased design freedom.

[0077] Sixth Embodiment Next, a sixth embodiment of the present disclosure will be described with reference to FIGS. 11A and 11B. Description of content overlapping with the first embodiment will be omitted. FIG. 11A is a schematic top perspective view showing an example structure of a mirror holder 50 in this embodiment, and FIG. 11B is a schematic bottom perspective view showing an example structure of the mirror holder 50 in this embodiment. As shown in FIGS. 11A and 11B, the mirror holder 50 has a top surface portion 57, a top surface extension portion 58, a positioning hole 58a, a first holder 53, a second holder 54, and a gap portion 56. The top surface portion 57 is a portion formed integrally with the first holder 53 and the second holder 54 to connect them, and corresponds to the connecting portion in this disclosure. Figures 11A and 11B show an example in which the top surface extension portion 58 extends in the width direction of the first holding portion 53 and the second holding portion 54, but it may also extend in the arrangement direction of the first holding portion 53 and the second holding portion 54, as in Figures 8A and 8B.

[0078] In the optical member and image projection device 100 of this embodiment, the top surface 57 is 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, and enabling weight reduction and increased design freedom.

[0079] Seventh Embodiment Hereinafter, a seventh embodiment of the present disclosure will be described in detail with reference to Fig. 12A to Fig. 15B. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate.

[0080] FIG. 12A is a schematic perspective view illustrating the structure of the primary mirror 20, FIG. 12B is a schematic horizontal cross-sectional view illustrating the structure of the primary mirror 20, and FIG. 12C is a schematic vertical cross-sectional view illustrating the structure of the primary mirror 20. The white arrows in FIGS. 12B and 12C schematically indicate the traveling direction of image light incident on the primary mirror 20. As shown in FIGS. 12A to 12C, the reflective surface of the primary mirror 20 is convex in the width direction (second direction) and concave in the height direction (first direction), forming a saddle shape. Therefore, the reflective surface of the primary mirror 20 imparts positive optical power to the image light in the height direction and negative optical power in the width direction.

[0081] Fig. 13 is a schematic diagram showing a configuration example of the image projection unit 10. As shown in Fig. 13, the image projection unit 10 includes a light source unit 11, an image display unit 12, a first plane mirror 13, and a second plane mirror 14. The image display unit 12 includes a far display region 12a and a near display region 12b. The dashed arrows in Fig. 13 schematically indicate the path (reference ray) of the center position of the far image light L1, and the dashed-dotted arrows schematically indicate the path (reference ray) of the center position of the near image light L2.

[0082] The light source unit 11 is a part that irradiates the image display unit 12 with irradiation light. In the example shown in FIG. 13 , the light source unit 11 is disposed on the rear side of the transmissive image display unit 12, and the irradiation light passes through the image display unit 12. However, a reflective image display unit 12 may be used, and the irradiation light may be emitted from the display surface side. The specific configuration of the light source unit 11 is not limited, and a light-emitting diode or a laser light source may be used. Furthermore, 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.

[0083] The image display unit 12 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 conventionally known devices 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. 13 , a liquid crystal display device is used as the image display unit 12. As will be described later, the image display unit 12 includes 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 far image light L1, and the near image displayed in the near display area 12b is irradiated as near image light L2. The far display area 12a and the near display area 12b may each be configured by separate display devices, but it is preferable to use a single display device divided into two areas.

[0084] The first plane mirror 13 is an optical member having a flat reflective surface. The reflective surface of the first plane mirror 13 is disposed at a position where the far image light L1 emitted from the far display area 12a is incident. The reflective surface of the first plane mirror 13 is inclined at a predetermined angle with respect to the far display area 12a, and reflects the incident far image light L1 toward the second plane mirror 14.

[0085] The second plane mirror 14 is an optical member having a flat reflecting surface. The reflecting surface of the second plane mirror 14 is disposed at a position where the far-distance 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 angle relative to the image display unit 12 by a predetermined angle, and reflects the incident far-distance image light L1 toward the primary mirror 20.

[0086] 13 , the first plane mirror 13 and the second plane mirror 14 are not disposed on the path of the near image light L2 emitted from the near display region 12b. Therefore, the near image light L2 emitted from the near display region 12b travels through the space between the first plane mirror 13 and the second plane mirror 14 toward the primary mirror 20. The near image light L2 is directly emitted onto 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 then emitted onto the primary mirror 20. As a result, a difference in optical path occurs between the near image light L2 and the far image light L1 before they reach the primary mirror 20, and the imaging positions of the virtual images P1 and P2 differ.

[0087] Here, an example has been shown in which the first plane mirror 13 and the second plane mirror 14 are used to generate an optical path difference between the near image light L2 and the far image light L1, but the specific configuration for generating the optical path difference is not limited thereto. Examples include a configuration in which a prism is used to branch the optical paths of the far image light L1 and the near image light L2 and the optical path length after branching is changed, and a configuration in which a reflecting prism is used to reflect the far image light L1 twice and transmit the near image light L2.

[0088] Fig. 14A is a side view illustrating the positional relationship between the image irradiator 10, the primary mirror 20, and the secondary mirror 30, and the path of the image light, and Fig. 14B is a top view illustrating the positional relationship between the image irradiator 10, the primary mirror 20, and the secondary mirror 30, and the path of the image light. The dashed lines shown in Fig. 14A and Fig. 14B schematically show the path of light irradiated from the end of the image irradiator 10. The double-headed arrows shown in Fig. 14A indicate the distance d1 between the image irradiator 10 and the center of the reflective surface of the primary mirror 20, and the distance d2 between the center of the reflective surface of the primary mirror 20 and the center of the reflective surface of the secondary mirror 30.

[0089] 14A, the y-axis component of the image light is reflected by the primary mirror 20, condensed with positive optical power, intermediately imaged at intermediate image position f, and then magnified as it reaches the secondary mirror 30. Also, as shown in FIG. 14B, the x-axis component of the image light is reflected by the primary mirror 20, magnified with negative optical power, and reaches the secondary mirror 30.

[0090] 15A is a schematic diagram illustrating the parallax caused by the difference, showing left-right parallax, and FIG. 15B is a schematic diagram illustrating the parallax caused by the difference, showing up-down parallax. When aberration occurs, the virtual image viewed by the left eye is drawn in solid lines as triangle PL, and the virtual image viewed by the right eye is drawn in dashed lines as triangle PR. In addition, the ideal virtual image that can be viewed at the same position with both eyes without aberration is drawn in dashed lines as triangle PI.

[0091] As shown in Figures 15A and 15B, when aberration occurs in the primary mirror 20 and the secondary mirror 30, parallax occurs in the image light reaching the viewpoint 40. When left-right parallax occurs as shown in Figure 15A, it is possible to eliminate the parallax by changing the convergence angle of the two eyes, and the impact of reduced visibility is small. However, when up-down parallax occurs as shown in Figure 15B, it is difficult to eliminate the parallax by moving the two eyes, and the impact of reduced visibility is significant.

[0092] In image projection device 100 of this embodiment, the reflective surface of primary mirror 20 has a saddle shape that is convex in the width direction and concave in the height direction, which reduces aberration in the width direction and improves the degree of freedom in designing secondary mirror 30. This allows priority to be given to aberration correction in the height direction when designing the reflective surface of secondary mirror 30, and improves the accuracy of aberration correction in the height direction.

[0093] Furthermore, because primary mirror 20 has a saddle-like shape and the accuracy of aberration correction in the height direction is improved, aberrations can be corrected well even if distance d1 from image projection unit 10 to primary mirror 20 is reduced. Therefore, by making distance d1 smaller than distance d2 and satisfying the relationship d1<d2, image projection device 100 can be made smaller and thinner.

[0094] Furthermore, although the specific lengths of distances d1 and d2 are not limited, distance d1 from image projection unit 10 to primary mirror 20 is preferably in the range of 30 mm to 100 mm, and more preferably in the range of 50 mm to 70 mm. If distance d1 is smaller than these ranges, the angle at which image light irradiated from image projection unit 10 expands over the entire reflective surface of primary mirror 20 becomes large, making aberration correction difficult. If distance d1 is larger than these ranges, it becomes difficult to make image projection device 100 smaller and thinner.

[0095] In this embodiment, the far distance image light is emitted from the far distance display region 12a, and the near distance image light is emitted from the near distance display region 12b. Furthermore, the positions at which the far distance image light and the near distance image light are incident on the reflecting surface of the primary mirror 20 differ in the height direction. Therefore, at least one of the positions at which the far distance image light and the near distance image light are reflected is shifted from the center position of the primary mirror 20 and the secondary mirror 30, which tends to increase aberration in the height direction. However, by forming the primary mirror 20 into a saddle-shaped configuration and improving the accuracy of aberration correction in the height direction, the parallax occurring in the virtual images P1 and P2 can be reduced, thereby improving visibility.

[0096] As described above, in the image projection device 100 of this embodiment, the reflective surface of the primary mirror 20 has a saddle shape that is concave in the first direction and convex in the second direction, and the image light reflected by the primary mirror 20 is reflected by the secondary mirror 30, thereby improving the accuracy of aberration correction and improving the visibility of the formed virtual images P1 and P2 (Eighth Embodiment).

[0097] Next, an eighth embodiment of the present disclosure will be described. Description of content overlapping with the seventh embodiment will be omitted. In the seventh embodiment, the image irradiating unit 10 irradiates the far-distance image light and the near-distance image light to form two virtual images P1 and P2 at different imaging positions. However, a single virtual image may be formed by irradiating only one image light.

[0098] In the image projection device 100 of this embodiment, the reflective surface of the primary mirror 20 is saddle-shaped, concave in the first direction and convex in the second direction, and the image light reflected by the primary mirror 20 is reflected by the secondary mirror 30, thereby improving the accuracy of aberration correction and improving the visibility of the virtual image that is formed.

[0099] Ninth Embodiment Hereinafter, an embodiment of the present disclosure will be described in detail with reference to Fig. 16 to Fig. 18. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant description will be omitted as appropriate.

[0100] Fig. 16 is a schematic diagram showing an example of the configuration of the image projection unit 10. As shown in Fig. 16, the image projection unit 10 includes a light source unit 11, an image display unit 12, a first plane mirror 13, and a second plane mirror 14. The image display unit 12 also includes a far display area 12a and a near display area 12b. The configuration of the image projection unit 10 shown in Fig. 16 is the same as the configuration of the image projection unit 10 shown in Fig. 13, and therefore, overlapping content will not be described again.

[0101] Fig. 17 is a schematic perspective view illustrating the paths of the far distance image light L1 and the near distance image light L2 irradiated from the image irradiator 10. In the example shown in Fig. 17, the far distance display region 12a and the near distance display region 12b are arranged side by side in a parallel direction in the image display unit 12. If the direction perpendicular to the parallel direction of the image display unit 12 is defined as the width direction, the far distance image light L1 and the near distance image light L2 are irradiated at an angle in the width direction with respect to the display surface of the image display unit 12. Therefore, the first plane mirror 13 and the second plane mirror 14 are arranged at positions shifted in the width direction with respect to the image display unit 12.

[0102] 16 and 17 , the far image light L1 emitted from the far display region 12a is incident on the first plane mirror 13, reflected, and travels toward the second plane mirror 14. The far image light L1 that reaches the second plane mirror 14 is reflected again and reaches the primary mirror 20. Furthermore, the first plane mirror 13 and the second plane mirror 14 are not disposed on the path of the near image light L2 emitted from the near display region 12b. Therefore, the near image light L2 emitted from the near display region 12b travels through the space between the first plane mirror 13 and the second plane mirror 14 and reaches the primary mirror 20.

[0103] 16 and 17 , the near image light L2 is directly irradiated onto 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 then irradiated onto 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 parallel direction of the image display unit 12. Furthermore, on the reflective 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 also differ. Due to this difference in optical distance and path, the distances and image positions of the virtual images P1, P2 from the windshield WS differ.

[0104] When the far 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 image light L1 and the near 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 that makes up the prism is greater than 1, it is difficult to make the difference in optical distance between the far image light L1 and the near image light L2 smaller than nW.

[0105] 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 far image light L1 to reach the second plane mirror 14 from the first plane mirror 13, and the degree of freedom in design is low. In addition, aberration occurs depending on the angle of incidence of the far image light L1 on the reflecting surface of the prism, making it difficult to improve the quality of the virtual image P1.

[0106] In the image projection device 100 of this embodiment, the far image light L1 propagates between the first plane mirror 13 and the second plane mirror 14 through air, which has a refractive index of 1. Therefore, the difference in optical distance between the far image light L1 and the near image light L2 is W, which is the product of the distance W in the parallel direction of the image display unit 12 and the refractive index of 1. Therefore, when the first plane mirror 13 and the second plane mirror 14 are used, the difference in optical distance between the far image light L1 and the near image light L2 can be reduced to approximately W. Furthermore, by arranging the second plane mirror 14 at a position away from the image display unit 12 in the parallel direction, the difference in optical distance can be made larger than W.

[0107] 18 is a schematic diagram illustrating the angles of the first plane mirror 13 and the second plane mirror 14 in the image projection unit 10. In this embodiment, the irradiation angle of the image light from the image display unit 12 differs for each region, and the far image light L1 emitted from the far display region 12a is irradiated at an irradiation angle α1, and the near image light L2 emitted from the near display region 12b is irradiated at an irradiation angle α2. Therefore, the main irradiation direction of the near image light L2 from the image display unit 12 is different from the main irradiation direction of the far image light L1.

[0108] Here, a virtual plane perpendicular to the reference ray of the far-distance image light directed toward the windshield WS is assumed, with the clockwise direction in the figure being the positive angular direction and the counterclockwise direction being the negative angular direction. The first plane mirror 13 is disposed at a first angle θ1 with respect to the virtual plane, and the second plane mirror 14 is disposed at a second angle θ2 with respect to the virtual plane. The rectangle indicated by the two-dot chain line in Figure 18 represents a virtual first plane mirror 13' disposed parallel to the second plane mirror 14. Therefore, there is an angular difference of Δθ = θ1 - θ2 between the reflective surfaces of the first plane mirror 13 and the second plane mirror 14.

[0109] As described above, in this embodiment, the first plane mirror 13 and the second plane mirror 14 are used to create a difference in optical distance between the far-distance image light L1 and the near-distance image light L2, eliminating the need to reduce the first angle θ1 and move the first plane mirror 13 closer to the far-distance display area 12a. Therefore, the irradiation angle α1 of the far-distance image light L1 emitted from the far-distance display area 12a can be brought closer to 90 degrees. In this case, the first angle θ1 of the first plane mirror 13 is preferably in the range of −60 degrees or more and −45 degrees or less. By setting the first angle θ1 of the first plane mirror 13 within this angle range, it is possible to suppress the occurrence of aberrations in the formation of the virtual image P1 using the far-distance image light L1.

[0110] Furthermore, Δθ, which is the difference between the first angle θ1 and the second angle θ2, is preferably in the range of −10 degrees or more and +10 degrees or less, and more preferably in the range of −5 degrees or more and +5 degrees or less. By setting Δθ within this angle range, it is possible to project a virtual image while suppressing astigmatism and image plane tilt. Furthermore, because the first plane mirror 13 and the second plane mirror 14 are used, the difference in the optical path is smaller than when a prism is used, thereby improving design freedom.

[0111] As described above, in the image projection device 100 of this embodiment, the far image light L1 emitted from the far display area 12a is reflected by the first plane mirror 13 and the second plane mirror 14, so that the image light can be appropriately split into a plurality of image lights, thereby achieving weight reduction and improving design flexibility (tenth embodiment).

[0112] Next, a tenth embodiment of the present disclosure will be described with reference to Fig. 19 . Description of content that overlaps with the ninth embodiment will be omitted. Fig. 19 is a schematic diagram illustrating an example configuration of the image projection unit 10 in this embodiment and the angles between the first plane mirror 13 and the second plane mirror 14. This embodiment differs from the ninth embodiment in that a polarizing reflector 15 is provided on the reflective surface of the second plane mirror 14.

[0113] 19 , the image projection unit 10 in the image projection device 100 of this embodiment includes an image display unit 12, a first plane mirror 13, a second plane mirror 14, and a polarizing reflector 15. The image display unit 12 includes a far display area 12a and a near display area 12b. The second plane mirror 14 may be made of a light-transmitting material or a light-blocking material.

[0114] The polarizing reflector 15 is an optical member that reflects polarized light in a predetermined direction and transmits polarized light in a direction intersecting the predetermined direction. In the example shown in Fig. 19, the polarizing reflector 15 is attached to the reflective surface of the second plane mirror 14, but the second plane mirror 14 itself may be configured as a free-standing plate-shaped polarizing reflector 15. The polarization direction of the light reflected by the polarizing reflector 15 is set to the polarization direction of the image light emitted from the image display unit 12. As a result, the far image light L1 emitted from the far display area 12a is reflected by the first plane mirror 13 and the polarizing reflector 15 and reaches the primary mirror 20.

[0115] The solid arrows in Figure 19 schematically show external light LO reaching the image projection device 100 from outside. The image projection device 100 is mounted on a vehicle or the like as shown in Figure 1 and irradiates image light toward the windshield WS. At this time, external light LO, such as sunlight incident from above the vehicle, is partially reflected by the secondary mirror 30 and the primary mirror 20 and reaches the image projection unit 10. Such external light LO may increase the surface temperature of the image display unit 12, causing deterioration. In particular, external light LO reaching the far display area 12a is condensed by the secondary mirror 30 and the primary mirror 20, which is likely to cause temperature increase and deterioration.

[0116] Here, the external light LO is unpolarized and includes polarized light reflected by the polarizing reflector 15 and polarized light that is transmitted through it. Therefore, of the external light LO that reaches the polarizing reflector 15, the polarized component in the above-mentioned predetermined direction is reflected toward the first plane mirror 13, while the polarized component perpendicular to the predetermined direction is transmitted through the polarizing reflector 15. If the second plane mirror 14 is made of a light-blocking material, the external light LO that has transmitted through the polarizing reflector 15 is absorbed by the second plane mirror 14. If the second plane mirror 14 is made of a light-transmitting material, the external light LO that has transmitted through the polarizing reflector 15 is absorbed by other components of the image projection device 100.

[0117] Therefore, the energy of the external light LO that reaches the distant display area 12a is half of the energy of the external light LO that is incident on the polarizing reflector 15, and temperature rise and deterioration of the distant display area 12a can be suppressed.

[0118] Eleventh Embodiment Hereinafter, an embodiment of the present disclosure will be described in detail with reference to Fig. 20 to Fig. 23. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant description will be omitted as appropriate.

[0119] FIG. 20 is a schematic diagram illustrating the projection of virtual images P1 and P2 using the image projection device 100 according to this embodiment. The dashed line in FIG. 20 indicates the optical path of far-distance image light (first image light) L1, which will be described later, and the dashed-dotted line indicates the optical path of near-distance image light (second image light) L2. As shown in FIG. 20 , the far-distance image light L1 and the near-distance image light L2 projected from the image projection device 100 are reflected by the windshield (display unit) WS and irradiated onto the driver's viewpoint. The driver visually recognizes virtual images P1 and P2 formed on extensions of the optical paths along which the far-distance image light L1 and the near-distance image light L2 are incident. In this embodiment, the image projection device 100 projects the far-distance image light L1 and the near-distance image light L2 to form two images P1 and P2, but the number of virtual images is not limited.

[0120] In this case, the trajectory of light reaching the viewpoint from the direction in which the virtual images P1 and P2 are viewed is defined as the reference ray. In other words, this reference ray can be considered to be substantially the same as the trajectory of light irradiated from the center of the effective area from which light is emitted in the image irradiation unit 10 when it reaches the viewpoint. Actual image light is irradiated over a predetermined area from the image irradiation unit 10, and the light beam spreads from each position on the display surface, and is condensed or expanded by the optical power of the reflective surfaces of the primary mirror 20 and the secondary mirror 30. Therefore, the reference ray shown in FIG. 20 does not represent the path of the irradiated light in the entire area of ​​the image irradiation unit 10.

[0121] The windshield WS is a portion of the vehicle that is provided in front of the driver's seat and transmits visible light. The windshield WS corresponds to the display unit in the present disclosure because the windshield WS, on the interior surface of the vehicle, reflects the far image light L1 and the near image light L2 incident from the image projection device 100 toward the viewpoint and transmits light from outside the vehicle toward the viewpoint. While an example in which the windshield WS is used as the display unit is shown here, a combiner may be provided as a display unit separate from the windshield WS and reflect light from the image projection device 100 toward the viewpoint. Furthermore, the display unit is not limited to being located at the front of the vehicle, and may be located to the side or rear as long as it projects an image toward the viewpoint of the passenger.

[0122] The virtual images P1 and P2 are images that are displayed as if they were formed in space when the far image light L1 and the near image light L2 reflected by the windshield WS reach the viewpoint (eyebox) of the occupant. The positions at which the virtual images P1 and P2 are formed are determined by the combined focal length of the projection optical unit included in the image projection device 100 and the windshield WS.

[0123] The viewpoint is the eye (eyebox) of the vehicle driver or passenger, and the image light enters the eyebox and reaches the retina, allowing the driver or passenger to view the formed virtual images P1 and P2.

[0124] In the image projection device 100 of this embodiment, a far image displayed in the far display area of ​​the image projection unit 10 is irradiated as far image light L1, and a near image displayed in the near display area is irradiated as near image light L2. Examples of far images displayed in the far display area include images calling attention to driving, emergency information, and other auxiliary information related to driving. Examples of near images displayed in the near display area include speed and volume indicators, driving direction guides, and the like.

[0125] FIG. 21 is a schematic cross-sectional view illustrating an overview of an image projection device 100 according to this embodiment. As shown in FIG. 21 , the image projection device 100 includes an image projection unit 10, a primary mirror 20, a secondary mirror 30, a housing 60, and an optical member 70. In the image projection device 100, each unit is controlled using a control unit (not shown) connected to each unit so as to be able to communicate information with the unit. The configuration of the control unit is not limited, but an example includes a CPU (Central Processing Unit) for information processing, a memory device, a recording medium, an information communication device, and the like. The control unit controls the operation of each unit according to a predetermined program and sends information including an image (image information) to the image projection unit 10.

[0126] The image irradiating unit 10 is a part that irradiates light containing an image as image light onto the primary mirror 20 based on image information from the control unit. In this embodiment, an example is shown in which two image lights displayed in two image display areas are irradiated onto the primary mirror 20 as far-distance image light L1 and near-distance image light L2.

[0127] The primary mirror 20 is an optical member that reflects the far image light L1 and the near image light L2 that arrive from the image irradiation unit 10 toward the secondary mirror 30. In the example shown in Fig. 21 , the primary mirror 20 is a flat reflecting mirror, but a concave or convex reflecting mirror may also be used. Furthermore, when the primary mirror 20 is configured with a curved surface, it is not limited to one with a constant curvature, and a paraboloid of revolution, an ellipsoid, a free-form surface mirror, etc. may be used.

[0128] The secondary mirror 30 is an optical member that reflects the far distance image light L1 and the near distance image light L2 that have arrived from the primary mirror 20 toward the windshield WS. In the example shown in Fig. 20, the secondary mirror 30 is a free-form mirror with an optically designed concave shape that is necessary for projecting the far distance image light L1 and the near distance image light L2 as virtual images P1, P2.

[0129] The reflective surfaces of the primary mirror 20 and the secondary mirror 30 are designed to expand the light diameter in the driver's viewing direction in order to project the far image light L1 and the near image light L2 as virtual images P1, P2 through the windshield WS. Here, expanding the light diameter in the viewing direction includes not only the case where the light diameter expands consistently after reflection, but also the case where the light diameter shrinks and expands after forming an image at an intermediate point. The combination of the primary mirror 20 and the secondary mirror 30 has the function of projecting the far image light L1 and the near image light L2 through the windshield WS and corresponds to the projection optical unit in this disclosure.

[0130] The housing 60 constitutes the outer shape of the image projection device 100 and is a container that houses each component. The housing 60 is provided with a light exit port for emitting the far image light L1 and the near image light L2. An angle adjustment unit for adjusting the angle of the secondary mirror 30 may be provided within the housing 60 to adjust the irradiation angle of the far image light L1 and the near image light L2 projected onto the windshield WS and change the imaging height of the virtual images P1 and P2. The housing 60 may also be provided with an optical filter that cuts out ultraviolet light and infrared light contained in light (external light) arriving from outside.

[0131] The optical member 70 is made of a light-transmitting material, is arranged on the light output side of the image irradiation unit 10, and is a part that repeatedly reflects the far image light L1 and transmits the near image light L2, thereby adjusting the optical path difference between the two. The configuration of the optical member 70 will be described later. There are no restrictions on the material that makes up the optical member 70, but it is preferable to use a resin material or glass material that has a high refractive index and high light transmittance.

[0132] 21 , the optical paths of the far image light L1 and the near image light L2 are depicted as a single straight arrow. However, the actual far image light L1 and near image light L2 are displayed in a predetermined area in the image irradiating unit 10, and have a predetermined area in a direction perpendicular to the traveling direction, as indicated by the range indicated by the dashed line in the figure. Furthermore, the far image light L1 and the near image light L2 may be reflected by the primary mirror 20 and travel with their light diameters reduced, and may be intermediately imaged at an intermediate image position F (not shown) between the primary mirror 20 and the secondary mirror 30.

[0133] Fig. 22 is a schematic cross-sectional view showing an example of the configuration of the optical member 70 in this embodiment. Of the light source unit, circuit board unit, and image display unit 12 that make up the image irradiation unit 10, Fig. 22 shows only the image display unit 12 on which the optical member 70 is disposed, and does not show the other parts. Fig. 23 is a schematic perspective view showing an example of the configuration of the optical member 70 in this embodiment.

[0134] 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 conventionally known devices 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. 22 , the image display unit 12 includes a far display area 12a and a near display area 12b that display a near image and a far image, respectively. In FIG. 22 , the far image light L1 emitted from the far display area 12a is indicated by a solid arrow, and the near image light L2 emitted from the near display area 12b is indicated by a dashed arrow.

[0135] A light source unit (not shown in FIG. 22 ) irradiates the image display unit 12 with irradiation light. In the example shown in FIG. 21 , the light source unit is disposed on the rear side of the transmissive image display unit 12, and the irradiation light passes through the image display unit 12. However, a reflective image display unit 12 may be used, and irradiation light may be emitted from the display surface side. The specific configuration of the light source unit is not limited, and a light-emitting diode or a laser light source may be used. Furthermore, when an organic EL display device is used as the image display unit 12, the light source unit and the image display unit 12 are integrally configured.

[0136] 22 and 23 , optical member 70 of this embodiment includes first portion 71a, second portion 71b, light incident surface 71c, refractive surface 71d, inclined surface 71e, inclined surface 71f, connecting portion 71g, and opening 71h. Reflecting surface 72 is provided on inclined surface 71f, and reflecting surface 73 is provided on inclined surface 71e. A gap 74 is provided between first portion 71a and second portion 71b.

[0137] The first portion 71a is a part of the optical member 70 made of a light-transmitting material and is a portion onto which the far-distance image light L1 is incident. The first portion 71a is integrally formed with the second portion 71b and the connecting portion 71g. The first portion 71a is disposed so as to overlap the far-distance display area 12a of the image display unit 12, and the surface facing the far-distance display area 12a is a light incident surface 71c. Parts of the surface of the first portion 71a form a refractive surface 71d and an inclined surface 71f.

[0138] The second portion 71b is a part of the optical member 70 made of a light-transmitting material, and is a portion from which the far-distance image light L1 is emitted. The second portion 71b is disposed opposite the first portion 71a, and a part of its surface forms an inclined surface 71e. In the examples shown in Figures 22 and 23, the second portion 71b is formed in a substantially plate-like shape.

[0139] The light incident surface 71c is a flat surface that constitutes a part of the surface of the first portion 71a, and is disposed opposite the far display area 12a of the image display unit 12. Although Fig. 22 shows an example in which the light incident surface 71c is disposed parallel to the far display area 12a, when the far image light L1 is refracted by the light incident surface 71c, the light incident surface 71c may be inclined at a predetermined angle with respect to the far display area 12a.

[0140] The refractive surface 71d is a surface that constitutes a part of the surface of the first portion 71a, and faces the gap portion 74. In Fig. 22, the refractive surface 71d is formed perpendicular to the image display unit 12, but it may be inclined at a predetermined angle with respect to the image display unit 12. In addition, although Fig. 22 shows an example in which the refractive surface 71d is provided near the boundary between the far display region 12a and the near display region 12b, the position is not limited as long as it is provided within a range that does not have an adverse optical effect on the near image light L2.

[0141] The inclined surface 71e constitutes a part of the surface of the second portion 71b, and is a surface on which the reflective surface 73 is provided, and is inclined at a predetermined angle with respect to the image display unit 12. In the example shown in Fig. 22, the surface of the second portion 71b opposite to the gap 74 is formed as the inclined surface 71e, but the surface facing the gap 74 may be formed as the inclined surface 71e and the reflective surface 73 may be provided.

[0142] The inclined surface 71f constitutes a part of the surface of the first portion 71a and is a surface on which the reflective surface 72 is provided, and is inclined at a predetermined angle with respect to the image display unit 12. Since the inclined surface 71f is inclined with respect to the image display unit 12, the first portion 71a between the refractive surface 71d and the inclined surface 71f has a tapered shape with a different thickness in the horizontal direction in the figure.

[0143] The connecting portion 71g is made of a light-transmitting material and is formed integrally with the first portion 71a and the second portion 71b. In Fig. 23, the connecting portion 71g is shown as a plate-shaped portion provided on the entire side of the gap portion 74, but the position and shape of the connecting portion 71g are not limited as long as the relative positional relationship between the first portion 71a and the second portion 71b can be maintained by being formed integrally with the first portion 71a and the second portion 71b.

[0144] The opening 71h is an opening formed in the optical member 70 and is provided opposite the near distance display region 12b. The opening 71h is surrounded by the first portion 71a, the second portion 71b, and the connecting portion 71g, and a region without the material constituting the optical member 70 is formed from the opening 71h toward the inside of the optical member 70, thereby forming a gap portion 74.

[0145] The reflecting surface 72 is a portion provided on the inclined surface 71f that reflects light. The configuration of the reflecting surface 72 is not limited, and a sheet-like member that reflects light may be attached to the inclined surface 71f, or a metal material or the like that reflects light may be vapor-deposited on the surface of the inclined surface 71f. Alternatively, the inclined surface 71f may be inclined at a greater angle than the critical angle, so that the difference between the refractive index of the material that constitutes the first portion 71a and the refractive index of air causes total reflection of light at the interface between the inclined surface 71f and air. The reflecting surface 72 corresponds to the first reflecting surface in this disclosure.

[0146] The reflecting surface 73 is a portion provided on the inclined surface 71e that reflects light. The configuration of the reflecting surface 73 is not limited, and a sheet-like member that reflects light may be attached to the inclined surface 71e, or a metal material or the like that reflects light may be vapor-deposited on the surface of the inclined surface 71e. Alternatively, the inclined surface 71e may be inclined at a greater angle than the critical angle, so that the difference between the refractive index of the material that constitutes the first portion 71a and the refractive index of air causes total reflection of light at the interface between the inclined surface 71e and air. The reflecting surface 73 corresponds to the second reflecting surface in this disclosure.

[0147] The void portion 74 is provided between the first portion 71 a and the second portion 71 b, and is a region that is free of the material that constitutes the optical member 70. The void portion 74 is also provided at a position that overlaps the near display region 12 b. Although an example is shown in which the void portion 74 is provided so as to penetrate the optical member 70 from the image display unit 12 side (light incident side) to the primary mirror 20 side (light exit side), the material that constitutes the optical member 70 may be present on either the light incident side or the light exit side.

[0148] As shown in FIG. 22 , the far image light L1 emitted from the far display region 12a enters the first portion 71a from the light incident surface 71c and reaches the reflecting surface 72 provided on the inclined surface 71f. The far image light L1 is reflected by the reflecting surface 72, bent back at the first portion 71a, and travels from the refracting surface 71d across the gap 74 to reach the second portion 71b. At this time, depending on the incident angle of the far image light L1 with respect to the refracting surface 71d, the far image light L1 is refracted at the interface between the refracting surface 71d and the gap 74. The far image light L1 that has reached the second portion 71b is reflected again by the reflecting surface 73 provided on the inclined surface 71e and reaches the primary mirror 20. Meanwhile, the near image light L2 emitted from the near display region 12b travels through the gap 74 to reach the primary mirror 20.

[0149] 22 , the near image light L2 is directly irradiated onto the primary mirror 20, whereas the far image light L1 is reflected by the reflecting surfaces 72, 73 and then irradiated onto 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 also differ. Due to this difference in optical distance and path, the distances and image positions of the virtual images P1, P2 from the windshield WS differ.

[0150] As described above, in the optical member 70 and image projection device 100 of this embodiment, the first portion 71 a, the second portion 71 b, and the connecting portion 71 g are integrally formed from a light-transmitting material, and the gap 74 is provided between the first portion 71 a and the second portion 71 b, thereby enabling weight reduction and improved design flexibility. Furthermore, the provision of the gap 74 allows the thickness of the optical member 70 to be reduced, thereby suppressing deformation due to sink marks when molding the optical member 70 and improving molding accuracy.

[0151] Furthermore, since the first portion 71 a has the light incident surface 71 c and the refraction surface 71 d, the inclination angles of the light incident surface 71 c and the refraction surface 71 d with respect to the traveling direction of the far image light L1 can be appropriately set to refract the far image light L1, thereby improving the degree of freedom in designing the path of the far image light L1 that travels from the first portion 71 a to the second portion 71 b.

[0152] Furthermore, by providing an opening 71h and a void 74 at a position overlapping the near display area 12b, even if the far image light L1 is refracted by the refractive surface 71d and enters the image display unit 12 side in the second part 71b, it is possible to prevent part of the light from being reflected or scattered by the material constituting the optical element 70 and becoming stray light.

[0153] Furthermore, by providing the connecting portion 71g on the side of the gap portion 74, the first portion 71a and the second portion 71b can be firmly integrated and their relative positional relationship can be maintained without having any optical effect on the far-distance image light L1 and the near-distance image light L2 traveling within the gap portion 74.

[0154] Twelfth Embodiment Next, a twelfth embodiment of the present disclosure will be described with reference to FIG. 24. Description of content that overlaps with the eleventh embodiment will be omitted. FIG. 24 is a schematic cross-sectional view showing an example configuration of an optical member 70 in this embodiment. This embodiment differs from the eleventh embodiment in that the image display unit 12 emits only one image light. As shown in FIG. 24, in this embodiment, a first portion 71a of the optical member 70 is disposed so as to overlap the image display unit 12, and the image display unit 12 is not provided in the gap portion 74.

[0155] 24 , image light emitted from the image display unit 12 enters the first portion 71a from the light incident surface 71c and reaches the reflecting surface 72 provided on the inclined surface 71f. The image light is reflected by the reflecting surface 72, bent back at the first portion 71a, and passes through the refracting surface 71d, crosses the gap 74, and reaches the second portion 71b. At this time, the image light is refracted at the interface between the refracting surface 71d and the gap 74, depending on the incident angle of the image light with respect to the refracting surface 71d. The image light that has reached the second portion 71b is reflected again by the reflecting surface 73 provided on the inclined surface 71e and reaches the primary mirror 20.

[0156] In the optical element 70 and image projection device 100 of this embodiment, the first part 71a, the second part 71b, and the connecting part 71g are integrally constructed from a light-transmitting material, and a gap part 74 is provided between the first part 71a and the second part 71b, thereby making it possible to reduce weight and improve design freedom.

[0157] Thirteenth Embodiment Next, a thirteenth embodiment of the present disclosure will be described with reference to Fig. 25. Description of content that overlaps with the eleventh embodiment will be omitted. Fig. 25 is a schematic cross-sectional view showing an example configuration of an optical member 70 in this embodiment. This embodiment differs from the twelfth embodiment in that a connecting portion 71i is provided on the light-emitting side of a gap portion 74.

[0158] The connecting portion 71i is made of a light-transmitting material and is formed integrally with the first portion 71a and the second portion 71b. Although Fig. 25 shows only an example in which the connecting portion 71i is provided on the light-emitting side of the gap 74, it may be used together with the connecting portion 71g provided on the side of the gap 74 shown in the eleventh embodiment.

[0159] 25 , image light emitted from the image display unit 12 enters the first portion 71a from the light incident surface 71c and reaches the reflecting surface 72 provided on the inclined surface 71f. The image light is reflected by the reflecting surface 72, bent back at the first portion 71a, and passes through the refracting surface 71d, crosses the gap 74, and reaches the second portion 71b. At this time, depending on the incident angle of the image light with respect to the refracting surface 71d, the image light is refracted at the interface between the refracting surface 71d and the gap 74. The image light that has reached the second portion 71b is reflected again by the reflecting surface 73 provided on the inclined surface 71e, passes through the connecting portion 71i, and then reaches the primary mirror 20.

[0160] In the optical member 70 and image projection device 100 of this embodiment, the first portion 71 a, the second portion 71 b, and the connecting portion 71 i are integrally formed from a light-transmitting material, and the gap 74 is provided between the first portion 71 a and the second portion 71 b, thereby enabling weight reduction and improving design flexibility. Furthermore, because the connecting portion 71 i is provided on the light-exiting side of the gap 74, even if the image light is refracted by the refracting surface 71 d and enters the second portion 71 b toward the image display unit 12, it is possible to prevent a portion of the light from being reflected or scattered by the material constituting the optical member 70 and becoming stray light.

[0161] Fourteenth Embodiment Next, a fourteenth embodiment of the present disclosure will be described with reference to Fig. 26. Description of content that overlaps with the eleventh embodiment will be omitted. Fig. 26 is a schematic cross-sectional view showing an example configuration of an optical member 70 in this embodiment. This embodiment differs from the twelfth embodiment in that a connecting portion 71j is provided on the light incident side of a gap portion 74.

[0162] The connecting portion 71j is made of a light-transmitting material and is formed integrally with the first portion 71a and the second portion 71b. Although Fig. 26 shows only an example in which the connecting portion 71j is provided on the light incident side of the gap 74, it may be used together with the connecting portion 71g provided on the side of the gap 74 shown in the eleventh embodiment.

[0163] 26 , image light emitted from the image display unit 12 enters the first portion 71a from the light incident surface 71c and reaches the reflecting surface 72 provided on the inclined surface 71f. The image light is reflected by the reflecting surface 72, bent back at the first portion 71a, and passes through the refracting surface 71d, crosses the gap 74, and reaches the second portion 71b. At this time, depending on the incident angle of the image light with respect to the refracting surface 71d, the image light is refracted at the interface between the refracting surface 71d and the gap 74. The image light that has reached the second portion 71b is reflected again by the reflecting surface 73 provided on the inclined surface 71e and reaches the primary mirror 20.

[0164] In the optical element 70 and image projection device 100 of this embodiment, the first part 71a, the second part 71b, and the connecting part 71j are integrally constructed from a light-transmitting material, and a gap part 74 is provided between the first part 71a and the second part 71b, thereby making it possible to reduce weight and improve design freedom.

[0165] Fifteenth Embodiment Next, a fifteenth embodiment of the present disclosure will be described with reference to Fig. 27. Description of content that overlaps with the eleventh embodiment will be omitted. Fig. 27 is a schematic cross-sectional view showing an example configuration of an optical member 70 in this embodiment. This embodiment differs from the twelfth embodiment in that a refractive surface 71d is provided on the second portion 71b.

[0166] 27 , in this embodiment, the refractive surface 71 d is provided on the second portion 71 b, and therefore the second portion 71 b between the refractive surface 71 d and the inclined surface 71 e has a tapered shape with a thickness that varies in the horizontal direction in the figure. Furthermore, the first portion 71 a is formed in a generally plate shape. Here, as in the twelfth embodiment, a connecting portion 71 g is provided on the side of the gap 74. However, as in the thirteenth embodiment, a connecting portion 71 i may be provided on the light output side, or as in the fourteenth embodiment, a connecting portion 71 j may be provided on the light input side.

[0167] 27 , image light emitted from the image display unit 12 enters the first portion 71a and reaches the reflecting surface 72 provided on the inclined surface 71f. The image light is reflected by the reflecting surface 72, bent back at the first portion 71a, traverses the gap 74, and enters the second portion 71b from the refracting surface 71d. At this time, depending on the incident angle of the image light with respect to the refracting surface 71d, the image light is refracted at the interface between the refracting surface 71d and the gap 74. The image light that has reached the second portion 71b is reflected again by the reflecting surface 73 provided on the inclined surface 71e, exits from the light exit surface 71k, and reaches the primary mirror 20.

[0168] In the optical element 70 and image projection device 100 of this embodiment, the first part 71a, the second part 71b, and the connecting part 71g are integrally constructed from a light-transmitting material, and a gap part 74 is provided between the first part 71a and the second part 71b, thereby making it possible to reduce weight and improve design freedom.

[0169] 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.

[0170] The configurations described in the following items also constitute part of the present disclosure. Item 9: An image projection device that projects image light onto a display unit for displaying a virtual image, comprising: an image irradiation unit that irradiates the image light; a primary mirror that reflects the image light incident from the image irradiation unit; and a secondary mirror that reflects the image light incident from the primary mirror, wherein the reflective surface of the primary mirror has a saddle shape that is concave in a first direction and convex in a second direction. Item 10: The image projection device according to Item 9, wherein the component of the image light reflected by the primary mirror in the first direction is intermediately imaged between the primary mirror and the secondary mirror. Item 11: The image projection device according to Item 9 or 10, wherein the distance from the image irradiation unit to the primary mirror is shorter than the distance from the primary mirror to the secondary mirror. Item 12: The image projection device according to Item 11, wherein the distance from the image irradiation unit to the primary mirror is in the range of 30 mm to 100 mm. Item 13: The image projection device according to any one of Items 9 to 12, wherein the image irradiating unit irradiates near image light from a near display area and far image light from a far display area, and includes a first plane mirror that reflects the far image light, and a second plane mirror that reflects the far image light reflected by the first plane mirror, wherein the near image light is incident on the primary mirror from the near display area and the far image light is incident on the second plane mirror. Item 14: An image projection device that projects image light onto a display unit for displaying a virtual image, the image projection device comprising: an image display unit that irradiates near image light from a near display area and far image light from a far display area; a first plane mirror that reflects the far image light; a second plane mirror that reflects the far image light reflected by the first plane mirror; and a projection optical unit that irradiates the near image light incident from the near display area and the far image light incident from the second plane mirror onto the image display unit.Item 15: The image projection device according to Item 14, wherein the first plane mirror is inclined at a first angle θ1 with respect to a virtual plane perpendicular to a reference ray of the far-distance image light directed toward the display unit, and the second plane mirror is inclined at a second angle θ2 with respect to the virtual plane, and a difference between the first angle θ1 and the second angle θ2 is in a range of -5 degrees or more and +5 degrees or less. Item 16: The image projection device according to Item 15, wherein the first angle θ1 is in a range of -60 degrees or more and -45 degrees or less. Item 17: The image projection device according to any one of Items 14 to 16, wherein the far-distance image light includes polarized light in a predetermined direction, and the second plane mirror includes a polarizing reflector that reflects light polarized in the predetermined direction and transmits light polarized in a direction intersecting the predetermined direction. Item 18: The image projection device according to any one of Items 14 to 17, wherein a main irradiation direction of the near-distance image light and a main irradiation direction of the far-distance image light are different. Item 19: The image projection device according to any one of items 14 to 18, wherein the projection optical unit includes a primary mirror that reflects the near image light and the far image light. Item 20: An optical member comprising: a first portion made of a light-transmitting material and having a first reflecting surface; a second portion arranged opposite the first portion and made of the light-transmitting material and having a second reflecting surface; a connecting portion integrally formed with the first portion and connecting the first portion and the second portion; and a gap portion provided between the first portion and the second portion and through which at least a portion of the light passes. Item 21: The optical member according to item 20, wherein at least a portion of the gap portion is formed to penetrate from the light incident side to the light exit side. Item 22: The optical member according to item 20 or item 21, wherein the connecting portion is provided on a side of the gap portion. Item 23: The optical member according to any one of items 20 to 22, wherein the connecting portion is provided on the light incident side of the gap portion. Item 24: The optical element according to any one of items 20 to 23, wherein the connecting portion is provided on the light exit side of the gap portion. Item 25: The optical element according to any one of items 20 to 24, wherein the first portion has a refractive surface having a different thickness from the first reflecting surface, and the refractive surface faces the gap portion and refracts the light.Item 26: The optical member according to any one of items 20 to 25, wherein the second portion has a refractive surface that varies in thickness from the second reflecting surface, and the refractive surface faces the gap to refract the light. Item 27: An image projection device that projects image light onto a display unit for displaying a virtual image, comprising: the optical member according to any one of items 20 to 26; an image irradiating unit that irradiates the image light; and a projection optical unit that irradiates the image light onto the display unit, wherein the image irradiating unit irradiates near image light from a near display region and far image light from a far display region, 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.

[0171] This application is based on Japanese Patent Application No. 2023-171710 filed on October 2, 2023, Japanese Patent Application No. 2023-188972 filed on November 3, 2023, Japanese Patent Application No. 2023-188973 filed on November 3, 2023, and Japanese Patent Application No. 2023-199454 filed on November 24, 2023, the contents of which are incorporated herein by reference.

Claims

1. An optical component having: a first reflecting surface; a second reflecting surface arranged 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; and a connecting portion that is formed integrally with the first holding portion and the second holding portion and connects them together.

2. The optical element according to claim 1, wherein the first holding portion and the second holding portion are made of a light-transmitting material.

3. The optical element according to claim 2, wherein 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.

4. The optical element according to claim 2, wherein the connecting portion is provided on a side of the first holding portion and the second holding portion.

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

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

7. The optical element according to claim 1, wherein 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.

8. An image projection device which projects 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 has an optical member as defined in any one of claims 1 to 7, wherein the image irradiating unit irradiates near image light from a near display area and irradiates 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.

9. An image projection device that projects image light onto a display unit for displaying a virtual image, comprising: an image irradiation unit that irradiates the image light; a primary mirror that reflects the image light incident from the image irradiation unit; and a secondary mirror that reflects the image light incident from the primary mirror, wherein the reflective surface of the primary mirror has a saddle shape that is concave in a first direction and convex in a second direction.

10. The image projection device according to claim 9, wherein the image light reflected by the primary mirror has a component in the first direction intermediately formed between the primary mirror and the secondary mirror.

11. The image projection device of claim 9, wherein the distance from the image illuminator to the primary mirror is less than the distance from the primary mirror to the secondary mirror.

12. The image projection device of claim 11, wherein the distance from the image projection unit to the primary mirror is in the range of 30 mm to 100 mm.

13. An image projection device as described in any one of claims 9 to 12, wherein the image irradiating unit irradiates near image light from a near display area and far image light from a far display area, the image irradiating unit has: a first plane mirror that reflects the far image light; and a second plane mirror that reflects the far image light reflected by the first plane mirror, wherein the near image light is incident on the primary mirror from the near display area and the far image light is incident on the second plane mirror.

14. An image projection device that projects image light onto a display unit for displaying a virtual image, comprising: an image display unit that irradiates near image light from a near display area and far image light from a far display area; a first plane mirror that reflects the far image light; a second plane mirror that reflects the far image light reflected by the first plane mirror; and a projection optical unit that irradiates the near image light incident from the near display area and the far image light incident from the second plane mirror onto the display unit.

15. The image projection device of claim 14, wherein the first plane mirror is inclined at a first angle θ1 with respect to a virtual plane perpendicular to a reference ray of the far-distance image light directed toward the display unit, the second plane mirror is inclined at a second angle θ2 with respect to the virtual plane, and the difference between the first angle θ1 and the second angle θ2 is in the range of -5 degrees or more and +5 degrees or less.

16. The image projection device according to claim 15, wherein the first angle θ1 is in the range of −60 degrees or more and −45 degrees or less.

17. The image projection device according to claim 14, wherein the distant image light includes polarized light in a predetermined direction, and the second plane mirror has a polarizing reflecting section that reflects polarized light in the predetermined direction and transmits polarized light in a direction intersecting the predetermined direction.

18. The image projection device according to claim 14, wherein a main irradiation direction of the near image light and a main irradiation direction of the far image light are different.

19. An image projection device according to any one of claims 14 to 18, wherein the projection optical section includes a primary mirror that reflects the near image light and the far image light.

20. An optical component having: a first portion made of a light-transmitting material and having a first reflecting surface; a second portion arranged opposite the first portion, made of the light-transmitting material and having a second reflecting surface; a connecting portion formed integrally with the first portion and the second portion and connecting the first portion and the second portion; and a gap portion provided between the first portion and the second portion and through which at least a portion of the light passes.

21. The optical element according to claim 20, wherein at least a portion of the void portion is formed penetrating from the light incident side to the light exit side.

22. The optical element according to claim 20, wherein the connecting portion is provided on a side of the gap portion.

23. The optical element according to claim 20, wherein the connecting portion is provided on the light incident side of the gap portion.

24. The optical element according to claim 20, wherein the connecting portion is provided on the light output side of the gap portion.

25. The optical element according to claim 20, wherein the first portion has a refractive surface having a different thickness from the first reflecting surface, the refractive surface facing the gap portion and refracting the light.

26. The optical element according to claim 20, wherein the second portion has a refractive surface having a different thickness from the second reflecting surface, the refractive surface facing the gap portion and refracting the light.

27. An image projection device that projects image light onto a display unit for displaying a virtual image, comprising: an optical element according to any one of claims 20 to 26; an image irradiation unit that irradiates the image light; and a projection optical unit that irradiates the image light onto the display unit, wherein the image irradiation 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.

Images