JP7779768B2 - Light equipment - Google Patents

Description

The present invention relates to a lighting fixture for use in vehicles, etc.

Traditionally, sensors installed in vehicles include cameras, LiDAR (Light Detection and Ranging), millimeter-wave radar, and other devices. Millimeter-wave radar, in particular, is an important sensor for driver assistance systems because it maintains high environmental resistance and is not affected by nighttime or backlit environments, or adverse weather conditions such as dense fog, rain, and snow.

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 material that reflects millimeter waves from other vehicles have become known.

For example, the low beam lamp unit of Patent Document 1 has a retroreflective step formed in a part of the illumination lens, particularly in an area (flange portion) that does not affect the light illumination in low beam distribution. This retroreflective step is made up of a large number of unit steps made up of protrusions in the shape of right-angled triangular pyramids, arranged on the rear surface of the flange portion (Patent Document 1/paragraphs 0020 and 0021, Figure 3).

JP 2015-185480 A

In the low beam lamp unit described above, the retroreflective element needs to be placed somewhere other than on the lamp's reflecting surface within the lamp unit, which poses the problem of either having to enlarge the lamp unit itself to accommodate the retroreflective element, or having to reduce the size of the retroreflective element.

The present invention was made in consideration of these circumstances, and aims to provide a compact lighting fixture that incorporates retroreflective material.

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 having 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.

In this 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 radar waves emitted from outside (e.g., another vehicle) pass through the mirror portion.

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 become aware of the vehicle's position, for example. This lamp does not require a large amount of space for the reflector and retroreflective material, allowing the device to be made more compact.

In the lamp of the present invention, the retroreflective material is preferably integrally molded on the surface of the resin body facing the light-reflecting surface.

With this configuration, the retroreflective material is integrally molded on the surface (back side) opposite the light-reflecting surface of the resin body that makes up 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 corner-shaped reflective surfaces, which allows for a wider directivity of reflected waves than other retroreflective shapes, resulting in the effect of obtaining uniform reflected waves regardless of the angle of incidence of the radar wave.

In addition, because the retroreflective material is formed to fit the three-dimensional shape of the reflector, it is able to reflect radar waves incident from various directions, further improving reflection efficiency in addition to the effects of the triangular pyramid structure mentioned above. Furthermore, as an integrated reflector, it can also lead to cost reductions.

Furthermore, in the lamp of the present invention, it is preferable that the island-shaped metal layer of the light-reflecting surface has a radar wave transmittance of 90% or more.

The island-shaped metal layer of the present invention transmits over 90% of radar waves. This allows the reflector of this lamp to reliably transmit radar waves emitted from outside and reflect them off the retroreflective material behind it.

Furthermore, 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.

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 incident radar waves can be reflected multiple times by the reflective surface of the reflex reflector and returned to the incident direction.

Furthermore, in the lighting fixture of the present invention, it is preferable that the reflector has a parabolic shape and the light source is disposed at the focal position of the parabolic surface.

The reflector has a parabolic shape, so it has 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.

1 is a front view of a vehicle lamp according to a first embodiment of the present invention; 2 is a cross-sectional view of the lamp device of FIG. 1 taken along the horizontal line AA. 2 is a cross-sectional view of the lamp device of FIG. 1 taken along the vertical direction (line BB). FIG. 4 is an enlarged view of an area S in FIG. 3 . FIG. 2 is a diagram showing the back side of a retroreflective material. FIG. 2 is a diagram showing the front side of a retroreflective material. FIG. 6 is a cross-sectional view of a vehicle lamp according to a second embodiment of the present invention.

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

[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 A-A) of the lamp device 1 in Fig. 1, and Fig. 3 is a vertical cross-sectional view (line B-B) of the lamp device 1 in Fig. 1.

Lamp device 1 is a lighting fixture, and is used in particular as a headlamp located on the left and right sides of the front of a vehicle. Lamp device 1 in Figure 1 shows one of multiple lamp devices that make up a headlamp. 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.

As shown in the cross-sectional view of Figure 2 (cross-section taken along line A-A in Figure 1), the lamp device 1 has a parabolic reflector 5 housed within a cylindrical housing 10. The front side of the housing 10 is covered by 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.

As shown in the cross-sectional view of Figure 3 (cross-section taken along line B-B in Figure 1), circuit boards 3 and 4 (the "light source" of the present invention) each mounted with a light-emitting element 2 are disposed within the housing 10. Below, we will explain 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.

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 can be fixed together using screws or thermal caulking, in addition to adhesive bonding.

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.

Figure 4 is an enlarged view of area S in Figure 3 (the lower housing 10 is omitted).

The surface side of the reflector 5 is a mirror portion 5M, which consists 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.

The island-shaped metal layer 52 is a collection of minute islands, a metal coating that has a metallic luster and is permeable to millimeter waves Le (electromagnetic waves in the 76-81 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.

Here, the island-shaped metal layer 52 has an island-shaped structure in which the metal layer is divided by fine cracks. Furthermore, the island-shaped metal layer 52 can reflect light from the light-emitting element 2 with sufficient reflectivity. Therefore, the mirror portion 5M fully functions as a reflector.

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.

The back side of the reflector 5 (mirror portion 5M) is provided with a retroreflective material 7 that reflects millimeter waves Le. More precisely, the retroreflective material 7 is integrally molded by applying a black metal layer 53, which is the retroreflective material 7, to the surface of the resin body 51 facing the island-shaped metal layer 52. This allows for size and cost reductions as a single product.

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.

The foamed resin body can be formed, for example, by sealing carbon dioxide gas or the like in the resin and generating bubbles. Because foamed resin has a low dielectric constant, it can achieve better radar wave transmission characteristics. The flat resin layer can also be formed by spraying a highly viscous resin such as epoxy resin.

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.

In other words, 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 consisting of multiple triangular pyramid structures, the triangular pyramid structures have corner-shaped reflective surfaces, which allows for a wider directivity of the reflected waves than other retroreflective shapes, resulting in the effect of obtaining a uniform reflected wave regardless of the angle of incidence of the millimeter waves Le.

Figure 5B also 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 other material that reflects millimeter waves Le. The retroreflective material 7 may also be a so-called reflex reflector (retroreflector), so its convex portion is not limited to a regular tetrahedron. Furthermore, 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 of different heights.

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 retroreflective material 7, before being reflected back in the incident direction (see Figure 4). Because these convex portions are formed to conform to the parabolic, three-dimensional shape of the retroreflective material 7, 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 Figure 2). This improves the reflection efficiency of millimeter waves Le.

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

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.

The lamp device 20 has a cylindrical housing that houses a circuit board 3, a reflector 25, and a retroreflective material 27. The circuit board 3 is fixed approximately in 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, in this embodiment, the retroreflective material 27 is provided behind the reflector 25 (mirror portion 25M) as one unit with a bracket 30, which is a separate member from the reflector 25.

The reflector 25 has a three-dimensional parabolic shape, with the front side being a mirror portion 25M and the back side being unprocessed or coated. Similar to the mirror portion 5M of the first embodiment, the mirror portion 25M consists of a resin body 51 and an island-shaped metal layer 52 formed on the resin body 51.

The island-shaped metal layer 52 is a collection 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 outside and reflect them off the retroreflective material 27.

The retroreflective material 27 is formed on the flat plate portion of the bracket 30 and is a corner reflector with multiple tetrahedral convex portions. It is preferable that the retroreflective material 27 be inserted into and fixed in the opening of the bracket 30.

In addition, the reflective surface of the retroreflective material 27 is provided with a black metal layer 53 made of aluminum or other material that reflects millimeter waves Le. Therefore, millimeter waves Le emitted from outside (for example, another vehicle) and transmitted through the reflector 25 enter the retroreflective material 27 behind it and are reflected in the direction of incidence.

In this way, because the retroreflector 27 is attached to the flat portion of the bracket 30, the reflective area 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.

The retroreflective material 27 may be a reflex reflector, and its structure is not limited to a regular tetrahedron. Furthermore, corner reflectors and reflex reflectors may have a single large convex portion, or may have a structure that combines multiple types of convex portions of different heights.

The present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit of the invention.

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 (5)

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. The lamp according to claim 1, wherein the retroreflective material is integrally molded onto the surface of the resin body facing the light-reflecting surface. A lamp according to claim 1 or 2, wherein the island-shaped metal layer of the light-reflecting surface has a radar wave transmittance of 90% or more. The lamp described in any one of claims 1 to 3, wherein the retroreflective material is a reflex reflector or a corner reflector, and has a metal coating on the reflective surface that reflects radar waves. 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.