Head-up display device

Abstract

To provide a head-up display device capable of suppressing the generation of stray light.SOLUTION: A head-up display device 100 comprises: a display surface 11a emitting display light L and inclined non-orthogonal to an optical axis center of the display light L extending in a Z-direction; one reflection mirror 30 reflecting the display light L emitted from the display surface 11a toward a windshield; a tabular hot mirror 50 positioned in an optical travelling direction of the display light L from the display surface 11a, reflecting infrared, transmitting the display light L, and inclined non-orthogonal to the Z-direction. The hot mirror 50 includes a plurality of side end faces. A side end face 51 closest to the display surface 11a, of the plurality of side end faces, is formed with a regular reflection suppression structure 55 for reducing regular reflectance in comparison with other side end faces.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a head-up display device. [Background technology]

[0002] The head-up display device described in Patent Document 1 includes a display unit that emits display light, a reflecting unit that reflects the display light from the display unit, and a hot mirror that is an optical element that transmits the display light traveling from the display unit to the reflecting unit (see paragraph 0028 of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 235284 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, external light such as sunlight is reflected by the side end surface of the hot mirror, and this reflected external light may become stray light and mix with the display light.

[0005] The present disclosure has been made in consideration of the above-described circumstances, and aims to provide a head-up display device that can suppress the generation of stray light. [Means for solving the problem]

[0006] In order to achieve the above object, a head-up display device according to the present disclosure includes: A head-up display device that emits display light representing an image toward a projection member, a display surface that emits the display light and is inclined non-orthogonally with respect to the optical axis center of the emitted display light; a reflecting mirror that reflects the display light emitted from the display surface toward the projection member; a plate-shaped hot mirror positioned in a light traveling direction of the display light relative to the display surface, reflecting infrared rays and transmitting the display light, and tilting non-orthogonally with respect to the optical axis center; the hot mirror has a plurality of side end surfaces; A first side end face of the plurality of side end faces that is closest to the display surface has a specular reflection suppression structure formed thereon that reduces the specular reflectance compared to a second side end face of the plurality of side end faces other than the first side end face. [Effects of the Invention]

[0007] According to the present disclosure, the occurrence of stray light can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a vehicle equipped with a head-up display device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view of the head-up display device according to the embodiment. [Figure 3] FIG. 2 is a perspective view of the head-up display device according to the embodiment with an upper case removed. [Figure 4] FIG. 2 is a perspective view of the hot mirror according to the embodiment. [Figure 5] FIG. 2 is a side view of the hot mirror according to the embodiment. [Figure 6] 10A and 10B are diagrams illustrating the specular reflection of external light when the specular reflection suppression structure is omitted from the hot mirror according to the embodiment. [Figure 7] FIG. 10 is a diagram showing specular reflection of external light on a hot mirror in a non-tilted state according to a comparative example. [Figure 8] FIG. 10 is a diagram showing specular reflection of external light on a hot mirror in a non-tilted state according to a comparative example. [Figure 9] 10 is a cross-sectional view showing a specular reflection suppression structure on a side end surface of a hot mirror according to a modified example of the present disclosure. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] A head-up display device according to an embodiment of the present disclosure will be described with reference to the drawings. As shown in FIG. 1, the head-up display device 100 is installed in the dashboard of a vehicle 200. The head-up display device 100 emits display light L that displays an image toward a windshield 201, which is an example of a projection target member of the vehicle 200. The display light L is reflected by the windshield 201 and reaches a viewer 1 (mainly the driver of the vehicle 200). As a result, the head-up display device 100 displays a virtual image V so as to be superimposed on an actual scene seen through the windshield 201. The virtual image V is displayed tilted by a tilt angle α with respect to a height direction H as viewed from the viewer 1.

[0010] As shown in FIG. 2, the head-up display device 100 includes a display device 10, a hot mirror 50, a reflecting mirror 30, a mirror driving mechanism 40, and a housing 60.

[0011] The display device 10 emits display light L. A specific configuration of the display device 10 will be described later. The reflecting mirror 30 is a concave mirror that reflects and magnifies the display light L that has passed through the hot mirror 50 from the display device 10 toward the windshield 201. The reflecting mirror 30 is disposed at approximately the same height as the display device 10 and in a position facing the display device 10. The mirror drive mechanism 40 is configured to rotate the reflecting mirror 30 around a rotation axis Ax extending along the vehicle width direction. When the reflecting mirror 30 rotates around the rotation axis Ax, the irradiation position of the display light L on the windshield 201 is adjusted in the height direction H.

[0012] 2, the housing 60 is made of a light-shielding resin or metal and has a hollow, substantially rectangular parallelepiped shape. Inside the housing 60, each component of the head-up display device 100 is housed. In detail, the housing 60 comprises a box-shaped lower case 60b that opens upward, an upper case 60a that closes the opening of the lower case 60b, and a blind cover 65 that forms an optical path space Sp within the lower case 60b.

[0013] The upper case 60a is formed in a rectangular frame shape, and has an opening 61 through which the display light L passes. A light-transmitting cover 63 is provided in the opening 61 of the upper case 60a. The light-transmitting cover 63 is in the shape of a curved rectangular plate that closes the opening 61 of the upper case 60a. The light-transmitting cover 63 is made of a light-transmitting resin such as acrylic, which allows the display light L to pass through.

[0014] A blind cover 65 and a reflecting mirror 30 are housed in the lower case 60b. As shown in FIG. 3, the display device 10 is attached to the outside of the lower case 60b, and the light-emitting side of the display device 10 is located within a region where part of the side wall of the lower case 60b is hollowed out.

[0015] The blind cover 65 is made of a light-blocking resin or metal, and is formed to partition the optical path space Sp from the hot mirror 50 to the reflecting mirror 30. The blind cover 65 is provided to hide components that may cause stray light to be generated in the lower case 60b from the optical path space Sp.

[0016] As shown in FIG. 3, the blind cover 65 includes a bottom wall portion 65a, side wall portions 65b and 65c, and an upper bridge portion 65d. The bottom wall 65a is positioned facing the inner bottom surface of the lower case 60b. The bottom wall 65a is formed over an area extending from a position facing the lower part of the surface of the hot mirror 50 on the optical path space Sp side, passing below the reflecting mirror 30, and reaching the back side of the reflecting mirror 30. The two side walls 65b, 65c are erected on the bottom wall 65a and are arranged to sandwich the display light L from the display device 10 in a direction perpendicular to the optical axis of the display light L (vehicle width direction). The upper bridge portion 65d extends so as to connect the upper ends of the pair of side wall portions 65b, 65c, and contacts the upper end side of the surface of the hot mirror 50 on the side of the optical path space Sp.

[0017] 2, the display device 10 includes a display panel 11, a light source substrate 12 on which a plurality of light sources 12a are mounted, optical lenses 13 and 14, and a prism 15. The display panel 11, the light source substrate 12, the optical lenses 13 and 14, and the prism 15 are held by a holder (not shown) in a state where they are aligned in the light traveling direction of the illumination light IL and the display light L so that the illumination light IL or the display light L is transmitted in the thickness direction of each plate. In the following description, the light traveling direction is defined as the Z direction, and two directions that are perpendicular to the Z direction and perpendicular to each other are defined as the X direction and the Y direction. The X direction extends along the vehicle width direction, and the Y direction extends along the vehicle height direction.

[0018] The plurality of light sources 12a are mounted on the surface of the light source substrate 12 facing the optical lens 13. The light sources 12a are LEDs (Light Emitting Diodes) and emit illumination light IL.

[0019] The optical lens 13 is located between the light source substrate 12 and the optical lens 14 in the Z direction. The optical lens 13 is a condenser lens, and is formed into a plate shape from a light-transmitting resin or glass. The optical lens 13 has the function of approximately collimating each light beam of the illumination light IL emitted from each light source 12a.

[0020] The optical lens 14 is located between the optical lens 13 and the display panel 11 in the Z direction. The optical lens 14 is a lenticular lens or a toroidal lens that distributes the illumination light IL from the optical lens 13 in accordance with the display surface 11a of the display panel 11.

[0021] The display panel 11 is located between the optical lens 14 and the prism 15 in the Z direction. The display panel 11 receives illumination light IL that has passed through the optical lenses 13 and 14 and emits display light L. The display panel 11 is a TFT (Thin Film Transistor) liquid crystal display panel. The display panel 11 has a display surface 11a that displays an image on the side that emits the display light L. The display surface 11a has a rectangular shape that is long in the X direction. The display panel 11 is provided in an inclined direction with respect to the light source substrate 12 and the optical lenses 13 and 14 that are provided in an orientation along the Y direction. Specifically, the display panel 11 is provided in an inclined direction with respect to the display surface 11a at an angle θ1 with respect to a reference direction A that extends in the Y direction. The angle θ1 is set so that the lower part of the display panel 11 approaches the light source substrate 12 while the upper part of the display panel 11 moves away from the light source substrate 12. By arranging the display surface 11a in an inclined direction, the generation of stray light, which is external light such as sunlight returning along the optical path of the display light L, is suppressed, and the virtual image V seen by the viewer 1 can be tilted, as shown in Figure 1.

[0022] As shown in FIG. 2, the prism 15 is a translucent member through which the display light L emitted from the display surface 11a passes. The prism 15 is made of a material having a refractive index n greater than that of air (n=1), such as glass or a transparent optical resin. Examples of transparent optical resins include acrylic resins and cyclic olefin resins. The prism 15 has an incident surface 15i facing the display surface 11a and an exit surface 15o facing the hot mirror 50. The incident surface 15i is formed as a flat surface parallel to the display surface 11a. The exit surface 15o is formed as an inclined surface inclined with respect to the incident surface 15i. The inclination of the exit surface 15o allows the virtual image V seen by the viewer 1 to be tilted, as shown in FIG. 1.

[0023] The hot mirror 50 transmits visible light, including the display light L, and reflects and absorbs infrared light, thereby suppressing a temperature rise in the display device 10. The hot mirror 50 is a rectangular plate elongated in the X direction. The hot mirror 50 is positioned to face the exit surface 15o of the prism 15. The hot mirror 50 is tilted at an angle θ2 with respect to a reference direction A extending in the Y direction. The angle θ2 is set so that the lower portion of the display panel 11 moves away from the optical path space Sp while the upper portion of the display panel 11 moves closer to the optical path space Sp. The angle θ2 is set to be larger than the angle θ1. In other words, the hot mirror 50 is tilted more than the display panel 11 with respect to the orientation of the light source substrate 12. As a result, the distance in the Z direction between the lower end of the hot mirror 50 and the lower end of the display surface 11a is smaller than the distance in the Z direction between the upper end of the hot mirror 50 and the upper end of the display surface 11a. The hot mirror 50 is an optical member having a substantially rectangular light-transmitting substrate made of acrylic resin and a reflective layer made of a multilayer interference film provided on the surface of the substrate (the surface on the optical path space Sp side or the surface on the prism 15 side). A deflector may be superimposed on the hot mirror 50.

[0024] The hot mirror 50 is inclined downward so as to move away from the optical path space Sp. The lower end of the hot mirror 50 is located below the bottom wall 65a of the blind cover 65 and faces the inner bottom surface of the lower case 60b.

[0025] As shown in FIG. 4, the hot mirror 50 has a plurality of side end faces 51 to 54 surrounding the periphery of the hot mirror 50. Side end surface 51 is a side surface on the lower end side of hot mirror 50, side end surface 52 is a side surface on the upper end side of hot mirror 50, and side end surfaces 53 and 54 are side surfaces on both sides in the X direction of hot mirror 50. A specular reflection suppression structure 55 that suppresses specular reflection of external light is formed on side end surface 51. The specular reflection suppression structure 55 is formed as a printed layer that absorbs light and is formed by printing black ink (a color that blocks light, such as black or gray).

[0026] As shown in FIG. 5, a marginal region 56 is formed on the outer periphery of the rectangular side end surface 51. The marginal region 56 is an area where the specular reflection suppression structure 55 is not formed, and has a rectangular frame shape. The specular reflection suppression structure 55 is formed in an area of ​​the side end surface 51 that is surrounded by the marginal region 56. The marginal region 56 has a pair of sides 56a extending in the longitudinal direction of the side end surface 51 and a pair of sides 56b extending in the lateral direction of the side end surface 51. The width W2 of the sides 56b is formed to be larger than the width W1 of the sides 56a. The width W1 is set to 0.3 mm to 0.7 mm, for example, approximately 0.7 mm. The width W2 is set to 1 mm to 5 mm, for example, approximately 3 mm. By forming the marginal region 56 in this way, the specular reflection suppression structure 55 is prevented from unintentionally reaching the optical surface (incident surface or exit surface) of the hot mirror 50, and a decrease in display quality is prevented. Furthermore, even if external light is specularly reflected in the marginal region 56, the effect on the display light L is small. The other side end faces 52 to 54 do not have the specular reflection suppressing structure 55 formed thereon, and therefore have a higher specular reflectance than the side end face 51. The specular reflectance is the ratio of the specularly reflected light flux to the incident light flux.

[0027] As a comparative example, as shown in Figure 7, when the hot mirror 50 is oriented along the reference direction A, i.e., when the angle θ2 is zero, the external light Lo reflected by the side end surface 51 of the hot mirror 50 is blocked by the bottom wall portion 65a of the blind cover 65. However, depending on the model of head-up display device, from the perspective of compactness, as shown in Fig. 8 as a comparative example, the space B1 between the side end surface 51 of the heated mirror 50 and the bottom wall portion 65a of the blind cover 65 may be designed to be smaller than the similar space B2 in the comparative example of Fig. 7. As a result, in the comparative example of Fig. 8, external light Lo reflected by the side end surface 51 of the heated mirror 50 cannot be blocked by the bottom wall portion 65a of the blind cover 65, and stray light may be generated. In particular, as shown in Figure 6, when the hot mirror 50 is inclined at an angle θ2 as in this embodiment, it moves away from the bottom wall portion 65a of the blind cover 65, making it even more difficult for the bottom wall portion 65a of the blind cover 65 to block the external light Lo, and the external light Lo reflected by the side end surface 51 of the hot mirror 50 is more likely to head toward the optical path space Sp. For this reason, as in this embodiment, it is necessary to take measures against stray light by forming a specular reflection suppression structure 55 on the side end surface 51 of the hot mirror 50. On the other hand, there is little need to take measures against stray light on the other side end surfaces 52 to 54, so the specular reflection suppression structure 55 is not formed thereon. Therefore, the specular reflection suppression structure 55 is not formed unnecessarily on the side end surfaces 52 to 54, and it is possible to manufacture a hot mirror 50 in which stray light countermeasures are taken only in necessary locations.

[0028] (effect) According to the embodiment described above, the following effects are achieved. (1) The head-up display device 100 emits display light L representing an image toward a windshield 201, which is an example of a projection target. The head-up display device 100 includes a display surface 11a that emits the display light L and is inclined non-orthogonally with respect to the center of an optical axis of the display light L extending in the Z direction, a single reflecting mirror 30 that reflects the display light L emitted from the display surface 11a toward the windshield 201, and a hot mirror 50 that is positioned in the light propagation direction of the display light L relative to the display surface 11a, has a plate shape that reflects infrared light and transmits visible light, and is inclined non-orthogonally with respect to the Z direction. The hot mirror 50 includes a plurality of side end surfaces 51 to 54. The side end surface 51, which is an example of a first side end surface and is closest to the display surface 11a among the plurality of side end surfaces 51 to 54, is formed with a specular reflection suppression structure 55 that reduces the specular reflectance compared to the side end surfaces 52 to 54, which are examples of second side end surfaces. According to this configuration, the specular reflection suppression structure 55 suppresses specular reflection of external light at the side end surface 51 of the hot mirror 50, thereby suppressing the generation of stray light. In particular, when the inclination angle θ2 of the hot mirror 50 is set larger than the inclination angle θ1 of the display surface 11a, the specularly reflected light at the side end surface 51 is more likely to enter the optical path space Sp, so it is particularly beneficial to form a specular reflection suppression structure 55 on the side end surface 51 as described above. Moreover, the display surface 11a is located at a position facing the reflecting mirror 30 in the Z direction. Therefore, the head-up display device 100 can be made thinner in the height direction.

[0029] (2) The hot mirror 50 is oriented such that the inclination angle θ2 of the hot mirror 50 with respect to the reference direction A perpendicular to the Z direction is greater than the inclination angle θ1 of the display surface 11a with respect to the reference direction A. When the tilt angle θ2 of the hot mirror 50 becomes large, specular reflection of external light by the side end surface 51 tends to cause stray light, as explained above with reference to Figures 6 to 8. For this reason, in this configuration, it is particularly beneficial to form a specular reflection suppression structure 55 on the side end surface 51.

[0030] (2) The specular reflection suppression structure 55 is formed on the side end surface 51 by a printed layer having light blocking properties. According to this configuration, the specular reflection suppression structure 55 can be easily formed on the side end surface 51.

[0031] (Variation) The present disclosure is not limited to the above-described embodiments and drawings, and modifications (including deletion of components) may be made as appropriate within the scope of the present disclosure.

[0032] In the above embodiment, the specular reflection suppression structure 55 is formed by printing a black light-blocking printing layer, but it is not limited to printing, and adhesive tape or a light-blocking material may also be adhered to the side end surface 51. Furthermore, the specular reflection suppression structure 55 may be formed by roughening the side end surface 51 so that the surface roughness is rougher than the other side end surfaces 52 to 54. In this case, the surface roughness of the side end surface 51 may be roughened by laser processing using a carbon dioxide laser or the like. By roughening the surface roughness, reflected light can be scattered and the amount of specular reflection can be reduced. The surface roughness may be uniform throughout the specular reflection suppression structure 55, or may vary depending on the location. For example, the surface roughness may be increased toward the center of the side end surface 51 in the X direction. This can further reduce specular reflection at the center of the side end surface 51 in the X direction. Furthermore, the specular reflection suppression structure 55 may be formed by increasing the surface roughness of the black print layer.

[0033] 9, the specular reflection suppression structure 55A may be formed as a periodic structure on the side end surface 51. Specifically, the specular reflection suppression structure 55A may be formed as a triangular wave shape aligned in the longitudinal direction (X direction) of the side end surface 51. This allows the specular reflection suppression structure 55A to reduce the specularly reflected light at the side end surface 51. The period of the triangular wave of the specular reflection suppression structure 55A may vary in the X direction, and may be formed so that the period of the triangular wave becomes shorter toward the center in the X direction of the side end face 51. This makes it possible to further reduce specular reflection at the center in the X direction of the side end face 51. The specular reflection suppression structure 55A may be formed in a triangular wave shape aligned in the short direction of the side end face 51.

[0034] In the above embodiment, the mirror driving mechanism 40 may be omitted. In the above embodiment, the head-up display device 100 may include a flat mirror or a concave mirror that reflects the display light L from the display device 10 toward the reflecting mirror 30. In the above embodiment, the prism 15 may be omitted. In the above embodiment, the display panel 11 may be provided oriented (angle θ1 is zero) along the reference direction A. Since the display panel 11 is not tilted and the prism 15 is omitted, the virtual image V is not tilted. In the above embodiment, the blind cover 65 may be omitted. Even in this case, it is effective to form the specular reflection suppression structures 55, 55A on the side end faces 51 because the inclination of the hot mirror 50 tends to cause stray light due to specular reflection at the side end faces 51. In the above embodiment, the width W1 and the width W2 may be set to the same length, or the width W2 may be set to be shorter than the width W1. In the above embodiment, the marginal area 56 may be omitted, and the specular reflection suppression structures 55, 55A may be formed over the entire area of ​​the side end surface 51. In the above embodiment, the inclination angle θ1 may be larger than the inclination angle θ2, or the inclination angle θ1 and the inclination angle θ2 may be the same angle.

[0035] In the above embodiment, the display device 10 is a type including the display panel 11, but is not limited to this and may be of any type as long as it is capable of emitting display light L from the display surface 11a. The display device 10 may be, for example, a type including an OLED (Organic Light-Emitting Diode), a type that receives light reflected by a DMD (Digital Micromirror Device) and displays an image on a transmissive screen, or the like.

[0036] In the above embodiment, the head-up display device 100 projects the display light L onto the windshield 201, but the display light L may be projected onto a combiner constituted by a plate-shaped half mirror, a hologram element, or the like, instead of the windshield 201.

[0037] The type of vehicle 200 on which the head-up display device 100 is mounted is not limited, and the head-up display device 100 can be applied to various vehicles such as four-wheeled automobiles, motorcycles, etc. The head-up display device 100 may also be mounted on vehicles other than the vehicle 200, such as an airplane, a ship, or a snowmobile, or may not be mounted on a vehicle. [Explanation of symbols]

[0038] 1...Viewer 10...display device, 11...display panel, 11a...display surface, 12...light source substrate, 12a...light source, 13, 14...optical lenses, 15...prism, 15i...incident surface, 15o...exit surface 30...Reflective mirror 40...Mirror drive mechanism 50...hot mirror, 51 to 54...side end faces, 55, 55A...regular reflection suppression structure, 56...margin area, 56a, 56b...side portions 60... housing, 60a... upper case, 60b... lower case, 61... opening, 63... light-transmitting cover, 65... blind cover, 65a... bottom wall portion, 65b, 65c... side wall portion, 65d... upper bridge portion 100...Head-up display device 200...vehicle, 201...windshield. α...tilt angle, θ1, θ2...tilt angle, A...reference direction, B1, B2...space, H...direction, L...display light, V...virtual image, IL...illumination light, Ax...rotation axis, Lo...external light, Sp...optical path space

Claims

1. A head-up display device that emits display light representing an image toward a projection member, a display surface that emits the display light and is inclined non-orthogonally with respect to the optical axis center of the emitted display light; a reflecting mirror that reflects the display light emitted from the display surface toward the projection member; a hot mirror positioned in a light traveling direction of the display light relative to the display surface, reflecting infrared rays and transmitting the display light, and inclined non-orthogonally with respect to the optical axis center; the hot mirror has a plurality of side end faces; a specular reflection suppression structure is formed on a first side end face of the plurality of side end faces that is closest to the display surface, the specular reflection suppression structure reducing the specular reflectance compared to a second side end face other than the first side end face of the plurality of side end faces; Head-up display device.

2. the hot mirror is provided in an orientation such that an inclination angle of the hot mirror with respect to a reference direction perpendicular to the optical axis center is larger than an inclination angle of the display surface with respect to the reference direction; The head-up display device according to claim 1 .

3. the specular reflection suppression structure is formed on the first side end surface by a print layer having a light-blocking property; The head-up display device according to claim 1 or 2.

4. the specular reflection suppression structure is formed of a rough surface having a surface roughness greater than that of the second side end surface; The head-up display device according to claim 1 or 2.

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