Lighting fixtures

Abstract

To provide a small-sized lighting fixture incorporating a retroreflective material therein.SOLUTION: A lamp device 1 includes: a light-emitting element 2; and a reflector 5 including a mirror part 5M for reflecting visible light Lv from the light-emitting element 2 forward. The mirror part 5M includes: a resin body 51; a light reflection surface comprising an island-like metal layer 52 formed on a surface of the resin body; and a retroreflective material 7 for reflecting a millimeter wave Le which is provided on a back surface side of the mirror part 5M.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a lamp for use in a vehicle or the like. [Background technology]

[0002] Conventionally, known sensors installed in vehicles include cameras, LiDAR (Light Detection and Ranging), millimeter-wave radar, etc. Millimeter-wave radar, in particular, is an important sensor for driving assistance systems, etc., because it maintains high environmental resistance and is not affected by nighttime or backlit environments, or bad weather such as dense fog, rain, and snow.

[0003] In addition, millimeter-wave radar can directly detect the distance and direction to an object, as well as the relative speed to the object, making it possible to detect objects at close range with high speed and accuracy.In recent years, headlights equipped with reflective materials that reflect millimeter waves from other vehicles have become known.

[0004] For example, the low beam lamp unit of Patent Document 1 has a retroreflective step formed in a part of the irradiating lens, particularly in an area (flange portion) that does not affect light irradiation in low beam light distribution. This retroreflective step has a large number of unit steps, each consisting of a protrusion in the shape of a right-angled triangular pyramid, arranged on the rear surface of the flange portion (Patent Document 1 / paragraphs 0020 and 0021, Figure 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-185480 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned low beam lamp unit, the retroreflective element needs to be placed at a position other than the lamp reflecting surface within the lamp unit, which creates the problem that the lamp unit itself must be enlarged to accommodate the retroreflective element, or the size of the retroreflective element must be reduced.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a small lamp that incorporates a retroreflective material. [Means for solving the problem]

[0008] In order to achieve the above object, a lamp of the present invention includes a light source and a reflector having a mirror portion that reflects light from the light source forward, The mirror portion has a resin body and a light-reflecting surface consisting of an island-shaped metal layer with a metallic luster formed on the surface of the resin body, and is characterized in that a retroreflective material that reflects radar waves is provided behind the mirror portion.

[0009] In the present invention, light from the light source is reflected by the mirror portion of the reflector and emitted forward. This mirror portion has a light-reflecting surface in the form of an island-shaped metal layer formed on the surface of a resin body, so that radar waves emitted from outside (for example, another vehicle) pass through the mirror portion.

[0010] In addition, a retroreflective material that reflects radar waves is provided behind the mirror. This allows radar waves that pass through the mirror to be reflected by this retroreflective material, allowing other vehicles to recognize the vehicle's position, for example. This lamp does not require a large space for the placement of the reflector and retroreflective material, allowing the device to be made compact.

[0011] In the lamp of the present invention, it is preferable that the retroreflective material is integrally molded on the surface of the resin body opposite the light-reflecting surface.

[0012] According to this configuration, the retroreflective material is integrally molded on the surface (back side) opposite the light-reflecting surface of the resin body that constitutes the mirror section, and is composed of multiple triangular pyramid structures. Each triangular pyramid shape is formed by combining three right-angled isosceles triangles at right angles to each other to form a pyramid shape, and is open toward the mirror section. In a configuration consisting of multiple triangular pyramid structures, the triangular pyramid structures have reflective surfaces arranged at corners, which allows for a wider directivity of reflected waves than other retroreflective shapes, and has the effect of obtaining uniform reflected waves regardless of the incident angle of the radar wave.

[0013] In addition, because the retroreflective material is formed to fit the three-dimensional shape of the reflector, it is possible to reflect radar waves incident from various directions, and in addition to the effect of the triangular pyramid structure, it is possible to further improve the reflection efficiency. Furthermore, as an integrated reflector, it can also lead to cost reduction.

[0014] In the lamp of the present invention, it is preferable that the island-shaped metal layer of the light reflecting surface has a transmittance of 90% or more for radar waves.

[0015] The island-shaped metal layer of the present invention transmits over 90% of radar waves, so the reflector of this lamp can reliably transmit radar waves emitted from outside and reflect them off the retroreflective material behind it.

[0016] In the lamp of the present invention, it is preferable that the retroreflective material is a reflex reflector or a corner reflector, and that the reflective surface has a metal coating that reflects radar waves.

[0017] A reflex reflector, for example, can be used as a retroreflective material. The reflective surface of a reflex reflector has a reflective metal coating, so that incident radar waves are reflected multiple times by the reflective surface of the reflex reflector and returned to the incident direction.

[0018] In the lamp of the present invention, it is preferable that the reflector has a parabolic shape, and the light source is disposed at a focal position of the parabolic surface.

[0019] The reflector has a parabolic shape, so there are two focal points. By placing a light source at the focal point, the light from the light source can be reflected and emitted in the desired direction. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a front view of a vehicle lamp according to a first embodiment of the present invention. [Figure 2] 2 is a cross-sectional view of the lamp device of FIG. 1 taken along the horizontal line AA. [Figure 3] 2 is a cross-sectional view of the lamp device of FIG. 1 taken along the vertical direction (line BB). [Figure 4] FIG. 4 is an enlarged view of an area S in FIG. [Figure 5A] FIG. 2 is a diagram showing the back side of a retroreflective material. [Figure 5B] FIG. 2 is a diagram showing the front side of a retroreflective material. [Figure 6] FIG. 5 is a cross-sectional view of a vehicle lamp according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] In the following, preferred embodiments of the present invention will be described, but these may be modified and combined as appropriate. In the following description and accompanying drawings, substantially the same or equivalent parts are designated by the same reference numerals.

[0022] [First embodiment] Fig. 1 is a front view of a lamp device 1 according to a first embodiment of the present invention. Fig. 2 is a horizontal cross-sectional view (line AA) of the lamp device 1 in Fig. 1, and Fig. 3 is a vertical cross-sectional view (line BB) of the lamp device 1 in Fig. 1.

[0023] The lamp device 1 is a lighting fixture, and is used particularly as a headlamp arranged on the left and right sides of the front of a vehicle. The lamp device 1 in Fig. 1 shows one of a plurality of lamp devices that make up a headlamp. The lamp device 1 is a headlamp for driving, but it may also be a device with the purpose and function of emitting light to the outside, such as a tail lamp or backlight.

[0024] As shown in the cross-sectional view of Fig. 2 (cross-section taken along line AA in Fig. 1), the lamp device 1 has a parabolic reflector 5 housed in a cylindrical housing 10. The front side of the housing 10 is covered with an outer lens 11. The housing 10 is made of resin or metal. A seal gasket 12 is provided at the rear end of the housing 10.

[0025] 3 (a cross section taken along line BB in FIG. 1), circuit boards 3 and 4 (the "light source" of the present invention), each having a light emitting element 2 mounted thereon, are disposed within the housing 10. The following describes the lower circuit board 3 and the curved surface of the lower half of the reflector 5, which reflects visible light from the light emitting element 2.

[0026] The circuit board 3 is positioned and fixed approximately in the center of the reflector 5. A light-emitting element 2 made of an LED is mounted on the circuit board 3 so that its light emission direction faces downward. The circuit board 3 and reflector 5 may be fixed together by screws or thermal caulking, in addition to being bonded with an adhesive.

[0027] The light-emitting element 2 is preferably disposed at the focal position of the parabolic surface of the reflector 5. By disposing the light-emitting element 2 at the focal position (below the two focal points), visible light can be reflected forward by the reflector 5 and emitted.

[0028] FIG. 4 is an enlarged view of area S in FIG. 3 (the lower housing 10 is omitted).

[0029] The surface side of the reflector 5 is a mirror portion 5M, which is made up of a resin body 51 and an island-shaped metal layer 52 formed on the resin body 51. The resin body 51 is made of a resin such as polycarbonate, acrylic, polyimide, epoxy, or polypropylene.

[0030] The island-shaped metal layer 52 is an aggregate of minute islands, and is a metal coating that has a metallic luster and is capable of transmitting millimeter waves Le (electromagnetic waves in the 76 to 81 GHz band, which corresponds to "radar waves" in this invention). The island-shaped metal layer 52 preferably has a millimeter wave Le transmittance of 90% or more. This allows the reflector 5 to reliably transmit millimeter waves Le emitted from outside and reflect them off the retroreflective material 7 behind it.

[0031] Here, the island-shaped metal layer 52 has an island-like structure in which the metal layer is divided by fine cracks. The island-shaped metal layer 52 can reflect light from the light-emitting element 2 with sufficient reflectance. Therefore, the mirror portion 5M can fully function as a reflector.

[0032] The metal of the island-shaped metal layer 52 may be, but is not limited to, aluminum, indium, palladium, nickel, nickel alloy, copper, copper alloy, silver, silver alloy, tin, tin alloy, etc. The island-shaped metal layer 52 may be formed by electroless plating of these metals.

[0033] The back side of the reflector 5 (mirror portion 5M) is provided with a retroreflector 7 that reflects millimeter waves Le. To be precise, the retroreflector 7 is integrally molded by applying a black metal layer 53, which is the retroreflector 7, to the surface of the resin body 51 that faces the island-shaped metal layer 52. This allows for size and cost reduction as a single product.

[0034] The resin body 51 may be a foamed resin such as polycarbonate. In this case, it is preferable to provide a flat resin layer to flatten the irregularities on the surface of the foamed resin body. Furthermore, an island-shaped metal layer 52 may be provided on the flat resin layer.

[0035] The foamed resin body can be formed by, for example, sealing carbon dioxide gas or the like in resin to generate bubbles. Foamed resin has a low dielectric constant, which allows for better radar wave transmission characteristics. The flat resin layer can also be formed by spraying a highly viscous resin such as epoxy resin.

[0036] Next, the retroreflective material 7 will be described in detail with reference to Figures 5A and 5B. Figure 5A shows the back side of the retroreflective material 7. The retroreflective material 7 is a corner reflector, and is composed of an array of regular tetrahedrons (with an opening on the mirror section 5M side) that are convex toward the rear.

[0037] That is, the retroreflective material 7 is composed of multiple triangular pyramid structures. Each triangular pyramid shape is formed by combining three right-angled isosceles triangles at right angles to each other to form a pyramid shape. In a configuration composed of multiple triangular pyramid structures, the triangular pyramid structures have reflective surfaces arranged at corners, which allows for a wider directivity of the reflected wave than other retroreflective shapes, and has the effect of obtaining a uniform reflected wave regardless of the angle of incidence of the millimeter wave Le.

[0038] 5B shows the front (reflective surface) side of the retroreflective material 7. The reflective surface of the retroreflective material 7 is provided with a black metal layer 53 made of aluminum or the like that reflects millimeter waves Le. The retroreflective material 7 may be a so-called reflex reflector (retroreflector), and therefore its convex portion is not limited to a regular tetrahedron. Corner reflectors and reflex reflectors may have a structure with a single large convex portion, or may have a structure that combines multiple types of convex portions with different heights.

[0039] Millimeter-waves Le incident from the front of the outer lens 11 pass through the mirror portion 5M of the reflector 5 and are reflected multiple times by the convex portions of the retroreflector 7, before being reflected back in the incident direction (see FIG. 4). These convex portions are formed along the parabolic three-dimensional shape of the retroreflector 7, so not only millimeter-waves Le incident on the outer lens 11 from the front direction, but also millimeter-waves Le incident from oblique directions are reflected back in the incident direction (see FIG. 2). This improves the reflection efficiency of millimeter-waves Le.

[0040] As described above, the lamp device 1 of this embodiment has an improved horizontal detection angle of approximately ±54° for detecting externally emitted millimeter waves Le compared to conventional products. This allows the driver to recognize the presence of a motorcycle or other vehicle traveling in the blind spot of the vehicle, thereby preventing an accident involving such a vehicle.

[0041] [Second embodiment] Next, a lamp device 20 according to a second embodiment of the present invention will be described with reference to the cross-sectional view shown in FIG.

[0042] The lamp device 20 has a cylindrical housing that houses a circuit board 3, a reflector 25, and a retroreflector 27. The circuit board 3 is fixed to approximately the center of the reflector 25, and a light-emitting element 2 made of an LED is mounted on the circuit board 3 so that its light emission direction faces downward. In addition, the retroreflector 27 of this embodiment is provided behind the reflector 25 (mirror portion 25M) and integrally with a bracket 30 that is a separate member from the reflector 25.

[0043] The reflector 25 has a three-dimensional parabolic shape, with a mirror portion 25M on the front side and no special processing or coating on the back side. Similar to the mirror portion 5M of the first embodiment, the mirror portion 25M is made of a resin body 51 and an island-shaped metal layer 52 formed on the resin body 51.

[0044] The island-shaped metal layer 52 is an aggregate of minute islands, and is a metal coating that has a metallic luster and is capable of transmitting millimeter waves Le (transmittance of 90% or more). This allows the reflector 25 to reliably transmit millimeter waves Le emitted from the outside and have them reflected by the retroreflective material 27.

[0045] The retroreflective material 27 is a corner reflector having a plurality of regular tetrahedral convex portions and is formed on the flat plate portion of the bracket 30. The retroreflective material 27 is preferably fixed by being fitted into an opening in the bracket 30.

[0046] Furthermore, a black metal layer 53 made of aluminum or the like that reflects millimeter waves Le is provided on the reflective surface of the retroreflective material 27. Therefore, millimeter waves Le that are emitted from the outside (for example, another vehicle) and that pass through the reflector 25 are incident on the retroreflective material 27 behind it and are reflected in the incident direction.

[0047] In this way, since the retroreflector 27 is attached to the flat portion of the bracket 30, the reflecting portion for millimeter waves Le can be made larger than the retroreflector 7 of the first embodiment without increasing the overall size of the lamp device 20.

[0048] The retroreflective material 27 may be any reflex reflector, and its structure is not limited to a regular tetrahedron. In addition, corner reflectors and reflex reflectors may have a single large convex portion, or may have a structure in which multiple types of convex portions with different heights are combined.

[0049] The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0050] 1, 20...lamp device, 2...light emitting element, 3, 4...circuit board, 5, 25...reflector, 5M, 25M...mirror portion, 7, 27...retroreflective material, 10...housing, 11...outer lens, 12...seal gasket, 30...bracket, 51...resin body, 52...island-shaped metal layer, 53...black metal layer

Claims

1. A light source and a reflector having a mirror portion that reflects light from the light source forward, the mirror portion has a resin body and a light-reflecting surface made of an island-shaped metal layer having a metallic luster formed on a surface of the resin body, A lamp characterized in that a retroreflective material that reflects radar waves is provided behind the mirror portion.

2. The lamp according to claim 1 , wherein the retroreflective material is integrally molded on a surface of the resin body opposite the light-reflecting surface.

3. 3. The lamp according to claim 1, wherein the island-shaped metal layer of the light reflecting surface has a transmittance of 90% or more for radar waves.

4. 4. The lamp according to claim 1, wherein the retroreflective material is a reflex reflector or a corner reflector, and has a metal coating on a reflective surface that reflects radar waves.

5. the reflector has a parabolic shape; 5. The lamp according to claim 1, wherein the light source is disposed at a focal position of the paraboloid.

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