Lamp device

Abstract

The present invention comprises: a lamp housing; a lamp cover that covers an opening portion of the lamp housing; a light source that is disposed in a lamp chamber formed by the lamp housing and the lamp cover; a light reflector; and a radar unit that transmits and receives radar waves. At least a part of the light reflector is an electromagnetic wave absorption part in which an island-shaped metal layer having metallic luster is formed on the surface of an electromagnetic wave absorber.

Description

Lamp device

[0001] The present invention relates to a lamp device, particularly a lamp device incorporating a radar device.

[0002] For driving assistance and autonomous driving, in addition to acceleration sensors and GPS sensors, various sensors such as cameras, LiDAR (Light Detection and Ranging), and millimeter-wave sensors are used.

[0003] In particular, millimeter-wave radar devices are not affected by environments such as at night or against the light, and adverse weather conditions such as thick fog, rainfall, and snowfall, and maintain high environmental resistance performance. Also, the distance to an object, the direction, and the relative speed with respect to the object can be directly detected. Therefore, it has the characteristic that it can detect even short-range objects at high speed and with high precision.

[0004] For example, Patent Document 1 discloses a vehicle lamp equipped with a light source unit and a millimeter-wave radar, and provided with an opaque design part that shields the millimeter-wave radar on a part of the resin cover.

[0005] Patent Document 2 discloses an aggregate of fine islands, and a metal film having a metallic luster and capable of transmitting electromagnetic waves. Also, Patent Document 3 discloses an electromagnetic wave-transmissive metallic luster member in which an indium oxide-containing layer provided continuously on the surface of a substrate and a metal layer including a plurality of parts that are at least partially discontinuous with each other are laminated on the indium oxide-containing layer.

[0006] Japanese Patent No. 5130192, Japanese Patent No. 5465030, Japanese Patent No. 6400062

[0007] In a vehicle lamp that incorporates a light source unit and a millimeter-wave radar inside, it is important to sufficiently suppress ghosts and the like caused by the reflection of radar waves by the reflector of the light source unit and the multiple reflection of radar waves.

[0008] However, conventionally, improvements regarding the degradation of the radar function due to the reflected wave of the main lobe of the radar wave that defines the radar field of view (FOV), and the direct wave and reflected wave of the side lobe that is secondarily generated in the main lobe have not been sufficient.

[0009] The present invention has been made in view of the above-mentioned points, and aims to provide a high-precision radar-equipped ramp device that has high resolution and a wide dynamic range, suppressing ghosting caused by reflected waves of the main lobe of the radar wave, and direct and reflected waves of the side lobes.

[0010] A lamp device according to one embodiment of the present invention comprises a lamp housing, a lamp cover covering the opening of the lamp housing, a light source disposed in a lamp chamber formed by the lamp housing and the lamp cover, a light reflector, and a radar unit for transmitting and receiving radar waves, wherein at least a portion of the light reflector is an electromagnetic wave absorbing portion in which island-shaped metal layers having a metallic luster are formed on the surface of the electromagnetic wave absorber.

[0011] This is a schematic perspective view showing the main parts of the lamp device of Embodiment 1 of the present invention. This is a top view of the lamp device, schematically showing its internal configuration. This is a schematic diagram showing the left-right main lobe and side lobes of the radar wave radiated from the radar unit. This is a schematic diagram showing the up-down main lobe and side lobes of the radar wave radiated from the radar unit. This is a schematic diagram showing the multiple reflected waves of the side lobes and main lobes and their absorption. This is a schematic top view showing the main parts of the lamp device of Embodiment 2. This is a diagram showing the surface of the extension facing the radar wave radiating surface of the transmitting and receiving antenna. This is a diagram showing the back surface of the extension (i.e., the surface opposite to the facing surface). This is a schematic cross-sectional view showing the cross-section of the extension and the main lobe and side lobes of the radar wave.

[0012] Preferred embodiments of the present invention will be described below, but these may be modified and combined as appropriate. In the following description and accompanying drawings, substantially identical or equivalent parts will be denoted by the same reference numerals.

[0013] Figure 1 is a schematic perspective view showing the main parts of the lamp device 10 of Embodiment 1 of the present invention. In the figure, a three-axis coordinate system is shown where the direction of travel of the vehicle to which the lamp device 10 is attached is the Y direction, the direction to the left of the direction of travel is the X direction, and the downward direction (direction of gravity) is the Z direction. The lamp device 10 according to this embodiment is a vehicle lighting fixture and is used as a headlamp located on the left and right front of the vehicle. Since the basic configuration of the left and right headlamps is the same, only the lamp device 10 (left headlight) located on the left front of the vehicle will be illustrated and described below.

[0014] Furthermore, although the explanation will be given using the case where the lamp device 10 is a headlamp for main driving as an example, it may also be a lamp device that has the purpose or function of emitting light outwards, such as a taillight or backup light.

[0015] In this specification, the automobile is used as an example of a vehicle, but the present invention is not limited to this. That is, in this specification, "vehicle" means a means of transport such as a ship or aircraft, and manned and unmanned means of transport or movement.

[0016] As shown in Figure 1, the lamp device 10 according to this embodiment has a light source unit 11 and a radar unit 20. The light source unit 11 and the radar unit 20 are mounted inside a housing 15. The housing 15 has an outer lens 17, which is a transparent cover that covers its front opening.

[0017] As shown in Figure 1, the lamp device 10 according to this embodiment has a light source unit 11 (multi-row reflector light source) in which a plurality of reflectors 12 (multi-row reflectors), which are light reflectors, are arranged in a row in the lateral direction (towards the side of the vehicle). More specifically, the light source unit 11 has an LED light source (not shown) which is a light-emitting part provided inside, and three reflectors 12 (reflector parts) that reflect the light emitted from the LED light source toward the front of the vehicle. In the following description, the case in which the light source unit 11 has a plurality of reflector parts will be described, but it may also have only one reflector part.

[0018] The three reflectors 12 (three reflector sections) arranged horizontally form the light distribution for the passing beam (low beam) and the driving beam (high beam). Each reflector 12 has a base section 12A and a mirror section 12M.

[0019] The base portion 12A is formed of an electromagnetic wave absorbing resin and is an electromagnetic wave absorber (radar wave absorber). Here, the electromagnetic wave absorbing resin that serves as the base material is preferably a resin that suppresses the transmission and reflection of electromagnetic waves with frequencies of 76 GHz to 81 GHz by 10 dB or more. For example, a resin can be selected that can suppress the reflection loss and transmission loss by 10 dB or more in the S11 and S21 measurements by a network analyzer.

[0020] As the electromagnetic wave absorbing resin, a thermoplastic resin containing an electromagnetic wave absorbing filler can be used. Examples of thermoplastic resins, though not limited to them, include polycarbonate (PC), acrylic, polyimide, epoxy, etc. Examples of electromagnetic wave absorbing fillers, though not limited to them, include carbon, insulating metal particles, soft magnetic metals, etc.

[0021] The mirror portion 12M has a curved light-reflecting layer. More specifically, the mirror portion 12M is constructed by forming island-shaped metal layers 12B (electromagnetic wave-transmitting metal layers), which are light-reflecting layers, on a part of the surface of the base portion 12A. That is, the base material (electromagnetic wave absorber) of the base portion 12A is common, and the base portion 12A and the mirror portion 12M are integrally formed, so that the entire reflector 12 functions as an electromagnetic wave absorber. It should be noted that the reflector 12 may have a configuration in which at least a part of it is an electromagnetic wave absorber.

[0022] The island-shaped metal layer 12B is an aggregate of fine metal islands, and is an electromagnetic wave-transmitting coating that has a metallic luster and is capable of transmitting electromagnetic waves. More specifically, in the island-shaped metal layer 12B, the metal islands are arranged independently, spaced apart from each other, or partially adjacent or in contact within the layer.

[0023] The metal used for the island-shaped metal layer 12B can be, for example, indium, palladium, nickel, nickel alloys, copper, copper alloys, silver, silver alloys, tin, tin alloys, etc., but is not limited to these. The island-shaped metal layer 12B can be formed by electroless plating of these metals or the like.

[0024] When the size of the metal island is sufficiently small compared to the wavelength of the radar wave, the radar wave is not affected by the metal island and penetrates the island-shaped metal layer 12B. For example, although this is just one example, a metal island with a size of several tens of nanometers (e.g., 20 nm) is sufficiently small compared to the wavelength of 76.5 GHz, which is 3.9 mm.

[0025] The lamp device 10 has a radar unit 20, which is a radar device, as an obstacle detection device. The radar unit 20 is positioned adjacent to the light source unit 11 to the left (X direction). The radar unit 20 has a radar wave radiating surface 20R on which a transmitting and receiving antenna 20A is provided. The radar wave radiating surface 20R is the antenna surface of the transmitting and receiving antenna 20A and is a surface perpendicular to the radar wave radiation axis CA.

[0026] In this embodiment, the radar unit 20 is a millimeter-wave radar device that emits radar waves (millimeter waves) from the transmitting and receiving antenna 20A and receives the reflected waves reflected by the target object with the transmitting and receiving antenna 20A.

[0027] In the radar unit 20, millimeter waves in the 76-81 GHz band, particularly those in the 76-77 GHz or 79 GHz band, are preferably used as radiated electromagnetic waves in terms of resolution and accuracy. However, the system is not limited to the above frequency bands, and other frequency bands, such as quasi-millimeter waves in the 24 GHz band, may also be used.

[0028] Figure 2 schematically shows the internal configuration of the lamp device 10 when viewed from above (top view). Figure 3A schematically shows the main lobe ML and side lobe SL of the radar wave in a top view, and Figure 3B schematically shows the main lobe ML and side lobe SL of the radar wave in a side view.

[0029] As shown in Figure 2, the radar unit 20 is positioned such that the radiation axis CA of the radar wave is tilted by an angle θ to the left (X direction) from the optical axis (Y direction) of the lamp device 10. Furthermore, the radar unit 20 is positioned so that the radiation axis CA lies within the horizontal plane (XY plane). The tilt angle θ of the radar unit 20 is, for example, 45° or 60°, or within the range of 45° to 60°, but is not limited thereto.

[0030] Furthermore, as shown in Figures 3A and 3B, the radar waves emitted from the radar unit 20 have a main lobe ML and side lobes SL. The main lobe ML is the beam for object detection and defines the radar field of view (FOV). For example, the field of view range in the left-right direction (Figure 3A, FOV1) is 150°, and the field of view range in the up-down direction (Figure 3B, FOV2) is 20°, but is not limited to these.

[0031] The radar wave side lobes SL extend outward from the main lobe ML, enclosing it in the left-right and up-down directions. Since the side lobes SL are beams that are secondarily generated in the main lobe ML, it is difficult to control only the side lobes SL.

[0032] As shown in Figure 2, the mirror portion 12M of the reflector 12 is positioned in front of the radar unit 20 and outside the illumination range of the main lobe ML. Furthermore, it is preferable that the reflector 12 and the radar unit 20 are arranged such that at least a portion of the base portion 12A and / or the mirror portion 12M is within the range of the side lobe SL. In this case, since the millimeter waves of the side lobe SL are absorbed by at least this portion, false images caused by the side lobe can be suppressed.

[0033] In conventional reflectors, where the reflector base material is a general-purpose resin and the light-reflecting surface is a metal surface made of a metal layer coating, the main lobe ML and side lobes SL of the radar wave incident on the metal surface (light-reflecting surface) undergo multiple reflections, producing a false image (ghost). Furthermore, multiple reflections occur, such as reflection from the surface of the outer lens and then reflection from the metal surface. Consequently, ghosts are generated in the detection signal of the radar unit 20, reducing the accuracy of the radar system.

[0034] In the lamp device 10 of this embodiment, radar waves are absorbed by the electromagnetic wave absorbing resin, which is the base material of the reflector 12, and the occurrence of ghosting can be suppressed without causing multiple reflections.

[0035] Specifically, as shown in Figure 4, the millimeter waves of the side lobe SL and the multiple reflected waves of the main lobe ML are absorbed by the reflector 12. More specifically, when the millimeter wave WS1 of the side lobe SL from the radar unit 20 directly hits the mirror portion 12M (light reflecting portion) of the reflector 12, the millimeter wave WS1 passes through the island-shaped metal layer 12B (light reflecting layer) and is absorbed by the base portion 12A (electromagnetic wave absorbing resin). Also, when the millimeter wave WS2 of the side lobe SL directly hits the base portion 12A, the millimeter wave WS2 is absorbed by the base portion 12A.

[0036] Furthermore, when the millimeter-wave WM1 of the main lobe ML reflected by the outer lens 17 and other components within the device directly strikes the mirror portion 12M, the millimeter-wave WM1 passes through the island-shaped metal layer 12B and is absorbed by the base portion 12A. Similarly, when the millimeter-wave WM1 directly strikes the base portion 12A, it is also absorbed by the base portion 12A.

[0037] Furthermore, the multiple reflected waves WMS of the main lobe ML and side lobe SL generated within the device are absorbed either after passing through the island-shaped metal layer 12B or directly by the substrate portion 12A.

[0038] Therefore, according to this disclosure, ghosting caused by direct and reflected waves of the radar wave side lobes is suppressed, and a high-resolution, high-dynamic-range, high-precision radar-equipped lamp device can be provided.

[0039] Although the description has focused on the case where the light source unit 11 has a multi-row reflector with multiple reflector sections, it is not limited to this case. The light source unit 11 may have only one reflector.

[0040] In the case of the multi-row reflector described above, regardless of the arrangement of the reflector 12 and the radar unit 20, the direct and reflected waves of the side lobe SL and the multiple reflected waves of the main lobe ML are effectively suppressed. This dramatically increases the degree of freedom in the arrangement of the radar unit 20 and makes it possible to provide a high-precision lamp device in which false images such as ghosts are easily suppressed.

[0041] Furthermore, although the above description has described a case in which the mirror portion 12M of the reflector 12 shares the same base material (electromagnetic wave absorber) as the base portion 12A, and the base portion 12A and the mirror portion 12M are integrally formed, the reflector 12 is not limited to this. The base portion 12A and the mirror portion 12M may be separate components that are combined to form the reflector 12. In this case, the electromagnetic wave absorber of the base portion 12A (first electromagnetic wave absorber) and the electromagnetic wave absorber of the mirror portion 12M (second electromagnetic wave absorber) may be different from each other. More specifically, the amount of attenuation of the electromagnetic wave absorber differs depending on the angle of incidence of the electromagnetic wave. Therefore, by using different types of electromagnetic wave absorbers, for example, in the portion where the side lobe SL is incident directly at an angle (e.g., the base portion 12A), an electromagnetic wave absorber with greater attenuation for oblique incidence than for perpendicular incidence is used, and in the portion where the main lobe ML is reflected by the outer lens 17, etc., and reflected waves with a shallow angle (close to perpendicular incidence) are incident (e.g., the substrate of the mirror portion 12M), an electromagnetic wave absorber with greater attenuation for perpendicular incidence is used, the reflected waves can be suppressed more effectively.

[0042] Furthermore, although the example described was when the island-shaped metal layer 12B is formed on the surface of the base portion 12A, a base layer made of a metal oxide such as indium tin oxide (ITO) may be provided between the island-shaped metal layer 12B and the base portion 12A.

[0043] FIG. 5 is a top view schematically showing a main part of the lamp device 30 of Example 2. The lamp device 30 of Example 2 is provided with an extension 31 which is a light reflector and decorates the lamp device 30 in addition to the lamp device 10 of Example 1. The extension 31 is provided parallel to the radar wave radiation surface 20R (antenna surface) of the transmission / reception antenna 20A of the radar unit 20, that is, perpendicular to the radiation axis CA of the radar wave. Note that the extension 31 only needs to be provided facing the radar wave radiation surface 20R, and may be arranged inclined with respect to the radar wave radiation surface 20R.

[0044] FIG. 6A is a view showing the surface of the extension 31 facing the radar wave radiation surface 20R of the transmission / reception antenna 20A, and FIG. 6B is a view showing the back surface of the extension 31 (that is, the surface on the opposite side of the surface facing the transmission / reception antenna 20A). Further, FIG. 7 is a cross-sectional view schematically showing the cross section of the extension 31 and the main lobe ML and side lobe SL of the radar wave.

[0045] As shown in FIG. 7, the extension 31 is provided in a range corresponding to the irradiation range of the main lobe ML, and an electromagnetic wave transmission part 33 made of a resin that transmits radar waves is provided. Further, an electromagnetic wave absorption part 34 is provided within the irradiation range of the side lobe SL around the electromagnetic wave transmission part 33, and at least a part of the electromagnetic wave absorption part 34 overlaps the side lobe SL. The electromagnetic wave absorption part 34 is formed of an electromagnetic wave absorption resin. Note that the electromagnetic wave absorption part 34 is provided in an annular shape surrounding the periphery of the electromagnetic wave transmission part 33.

[0046] On the back surface of the extension 31, that is, on the back surfaces of the electromagnetic wave transmission part 33 and the electromagnetic wave absorption part 34, an island-shaped metal layer 35 which is an electromagnetic wave transmissive metal layer is coated. Therefore, the main lobe ML of the radar wave radiated from the transmitting and receiving antenna 20A passes through the electromagnetic wave transmission part 33 and is radiated to the outside, enabling obstacle detection. On the other hand, the side lobe SL is absorbed by the electromagnetic wave absorption part 34, and the multiple reflected waves of the main lobe ML and the side lobe SL are absorbed by the electromagnetic wave absorption part 34. In other words, the electromagnetic wave absorption part 34 is arranged outside the range of the main lobe ML of the radar wave. Also, at least a part of the electromagnetic wave absorption part 34 is arranged within the range of the side lobe SL.

[0047] Therefore, the reflection of the side lobe SL by the members provided inside the lamp device 30 such as the outer lens 17 and the light source unit 11, and the multiple reflections of the main lobe ML and the side lobe SL are suppressed. For example, the multiple reflection of the radar wave by the reflector 12 of the light source unit 11 is further suppressed by the extension 31. Also, since the back surface of the extension 31 has a metallic appearance due to the island-shaped metal layer 35, it functions as a design component capable of suppressing multiple reflections.

[0048] As described in detail above, according to the present disclosure, it is possible to provide a high-precision lamp device equipped with a radar device that suppresses ghosts and the like caused by the reflected wave of the main lobe of the radar wave and the direct wave and reflected wave of the side lobe, has high resolution, and has a wide dynamic range.

[0049] 10, 30: Lamp device 11: Light source unit 12: Reflector 12A: Substrate part 12B: Island-shaped metal layer 12M: Mirror part 15: Housing 17: Outer lens 20: Radar unit 20A: Transmitting and receiving antenna 20R: Radar wave radiation surface 31: Extension 33: Electromagnetic wave transmission part 34: Electromagnetic wave absorption part 35: Island-shaped metal layer CA: Radiation axis ML: Main lobe SL: Side lobe

Claims

1. A lamp device comprising: a lamp housing; a lamp cover covering the opening of the lamp housing; a light source disposed in a lamp chamber formed by the lamp housing and the lamp cover; a light reflector; and a radar unit for transmitting and receiving radar waves, wherein at least a portion of the light reflector is an electromagnetic wave absorbing part in which island-shaped metal layers having a metallic luster are formed on the surface of the electromagnetic wave absorber.

2. The lamp device according to claim 1, wherein the electromagnetic wave absorbing section is located outside the range of the main lobe of the radar wave.

3. The lamp device according to claim 1, wherein the electromagnetic wave absorbing section is arranged within the range of the side lobes of the radar wave.

4. The lamp device according to claim 1, wherein the light reflector has a base portion that is integrally formed with the electromagnetic wave absorbing portion using the electromagnetic wave absorbing portion of the electromagnetic wave absorbing portion as a common base material.

5. The lamp device according to claim 1, wherein the light reflector has a base portion made of an electromagnetic wave absorber, and the electromagnetic wave absorber of the base portion and the electromagnetic wave absorber of the electromagnetic wave absorbing portion are different from each other.

6. The lamp device according to claim 1, wherein the radar unit is arranged such that the radiation axis of the radar wave is within a range of 45° to 60° laterally from the optical axis of the lamp device.

7. The lamp device according to any one of claims 1 to 6, wherein the light reflector is a reflector that reflects light from the light source.

8. The lamp device according to claim 7, wherein the reflector is a multi-row reflector having a plurality of reflector sections.

9. The lamp device according to any one of claims 1 to 3, 6, wherein the light reflector is an extension for decorating the lamp device.

10. The lamp device according to claim 9, wherein the light reflector is positioned opposite the radar wave radiating surface of the radar unit and has an electromagnetic wave transmitting portion provided corresponding to the irradiation range of the main lobe of the radar wave.

11. The lamp device according to claim 10, wherein the light reflector is covered with an island-shaped metal layer having a metallic luster on the surface opposite to the surface facing the radiating surface.

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