Lighting unit and lamp device

Abstract

The present invention provides a light-emitting unit and a lamp device. The lamp device can suppress the attenuation or reflection of radar waves caused by a light guide, and will not change the radar wave radiation pattern, and there is no loss of radar function. The lamp device also has: a light guide, which covers at least a portion of the electromagnetic wave radiation surface of the radar device, and a light source, which supplies light to the light guide. When the thickness of the light guide is set to TG and the wavelength of the radiated electromagnetic wave emitted by the radar device in the light guide is set to λd, TG is set in the following manner: when the reflection loss of the light guide relative to the radiated electromagnetic wave is less than the transmission loss, TG < λd / 2 is satisfied; when the reflection loss is greater than the transmission loss, the reflection loss is made less than -10dB.

Description

Technical Field

[0001] The present invention relates to a light emitting unit and a lamp device, and more particularly to a lamp device for a vehicle having a light emitting unit and a radar device built therein, wherein the light emitting unit is mounted on the vehicle and used for the radar device. Background Art

[0002] In order to perform 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 also used.

[0003] In particular, millimeter wave radar is not affected by nighttime or backlit environments, fog, rain, snow and other bad weather, and can maintain high environmental resistance. In addition, it can directly detect the distance and / or direction to the object, and the relative speed to the object. Therefore, it has the characteristics of being able to detect objects at close range at high speed and high precision.

[0004] There is proposed a vehicle lamp in which a millimeter-wave radar is mounted in a lamp chamber and a light guide member that transmits millimeter waves is provided between a front cover and the millimeter-wave radar (for example, Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 4842161 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, if a light-guiding component is arranged in front of the millimeter-wave radar, the electromagnetic waves emitted from the millimeter-wave radar will be reflected and absorbed by the light-guiding component due to the influence of the relative dielectric constant and dielectric loss tangent of the light-guiding component, and the radiation power of the radiated electromagnetic waves will be reduced, which will become a cause for a significant reduction in the detection performance of the millimeter-wave radar.

[0010] Therefore, usually, by using light guide components (light guide rods, etc.) used in automobile headlights, millimeter-wave radars, etc. are not visible from the outside to achieve aesthetic appearance, but this also constitutes a major cause of damage to the radar function.

[0011] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a light emitting unit which can suppress attenuation or reflection of radar waves and does not change the radar wave radiation pattern even when arranged in front of the radar and does not hinder the function of the radar.

[0012] The present invention has been completed in view of the above-mentioned problems, and its purpose is to provide a lamp device that can suppress the attenuation or reflection of radar waves caused by a light guide (light guide component) and will not damage the function of the radar even if a DRL (Daytime Running Lamps) or a turn signal is arranged in front of the radar, and will not change the electromagnetic wave radiation pattern.

[0013] Another object of the present invention is to provide a lamp device capable of suppressing a decrease in receiving sensitivity of a radar due to thermal noise of a light source that supplies light to a light guide.

[0014] Means for solving problems

[0015] A lighting device according to one embodiment of the present invention includes a lighting unit and a radar device.

[0016] The lamp device further comprises: a light guide body which covers at least a portion of the electromagnetic wave radiating surface of the radar device, and

[0017] a light source that supplies light to the light guide,

[0018] When the thickness of the light guide is set to TG and the wavelength of the radiated electromagnetic wave emitted by the radar device in the light guide is set to λd, TG is set in the following manner: when the reflection loss of the light guide with respect to the radiated electromagnetic wave is less than the transmission loss, TG<λd / 2 is satisfied; when the reflection loss is greater than the transmission loss, the reflection loss is made less than -10dB.

[0019] A light emitting unit according to another embodiment of the present invention comprises:

[0020] a light guide disposed in front of an electromagnetic wave radiating surface of the radar device and configured to cover at least a portion of the electromagnetic wave radiating surface, and

[0021] a light source that supplies light to the light guide,

[0022] When the thickness of the light guide is set to TG and the wavelength of the radiated electromagnetic wave emitted by the radar device in the light guide is set to λd, TG is set in the following manner: when the reflection loss of the light guide with respect to the radiated electromagnetic wave is greater than the transmission loss, TG=n×λd / 2 is satisfied, wherein n is a natural number; when the reflection loss is greater than the transmission loss, the reflection loss is made less than -10dB.

[0023] A lighting device according to another embodiment of the present invention includes a lighting unit and a radar device.

[0024] The lamp device further comprises: a light guide body which is arranged between the light-transmitting cover and the electromagnetic wave radiating surface of the radar device and covers at least a part of the electromagnetic wave radiating surface of the radar device, and

[0025] a light source that supplies light to the light guide,

[0026] When viewed from a direction perpendicular to the electromagnetic wave radiating surface, the area of ​​the light-transmitting cover overlapping the electromagnetic wave radiating surface, i.e., the area corresponding to the radiating surface, the light guide, and the electromagnetic wave radiating surface are arranged in parallel with each other.

[0027] The radiation surface corresponding area of ​​the light-transmitting cover and the light guide are configured in such a manner that they have the following size and configuration: when viewed from a direction perpendicular to the electromagnetic wave radiation surface, the radiation surface corresponding area and the light guide cover the entire surface of the electromagnetic wave radiation surface.

[0028] The thickness TK of the region corresponding to the radiation surface of the light-transmitting cover is set so that the reflection loss of the electromagnetic wave incident on the region corresponding to the radiation surface of the light-transmitting cover is -10 dB or less.

[0029] The thickness TG of the light guide is set so that the reflection loss of the electromagnetic wave incident on the light guide is less than -10 dB.

[0030] The interval C1 between the radiation surface corresponding region and the light guide is set so that the reflection loss of the electromagnetic wave incident on the radiation surface corresponding region and the light guide is less than -10 dB.

[0031] Brief description of the attached figure

[0032] Figure 1 This is a diagram schematically showing an example of the internal structure of a lamp device according to an embodiment of the present invention.

[0033] Figure 2 It is a perspective view showing the arrangement of the millimeter wave radar unit 15 and the light emitting unit 16 .

[0034] Figure 3A 1 and 2 are diagrams showing a state where the light guiding member 18A and the antenna surface 15S are viewed from the antenna surface 15S side of the millimeter wave radar unit 15 .

[0035] Figure 3B It is a diagram schematically showing a cross section of the millimeter wave radar unit 15 and the light guiding member 18A.

[0036] Figure 4 The diagram schematically shows how the millimeter wave MW (wavelength λ) emitted from the millimeter wave radar unit 15 passes through the light guiding member 18A (thickness TG).

[0037] Figure 5 It is a perspective view showing a modified example of the structure of the light source 17A and the light guide member 18A of the light emitting unit 16 and showing an electromagnetic wave absorber 21 that absorbs thermal noise radiated from the light source 17 .

[0038] Figure 6 1 is a diagram showing a modified example, in which the light guide 18 includes a light guide member 18A and a light guide member 18B, and the light guide member 18A and the light guide member 18B are different from each other.

[0039] Fig. 7A 1 is a diagram showing a modification example, and shows a light guide member 18C including a light guide member 18A and a light diffusion member 23 provided on the light guide member 18A.

[0040] Figure 7B It is an enlarged cross-sectional view schematically showing the cross section of the light guide member 18C in an enlarged manner.

[0041] Fig. 8A It is a plan view schematically showing the arrangement and configuration of the millimeter wave radar unit 15 , the light guide member 18D, and the transparent cover 12 in another embodiment of the present invention.

[0042] Figure 8B It is a cross-sectional view schematically showing the arrangement and configuration of the millimeter wave radar unit 15 , the light guide member 18D, and the transparent cover 12 as viewed from the WW line. DETAILED DESCRIPTION

[0043] Hereinafter, preferred embodiments of the present invention will be described, and these preferred embodiments may be appropriately modified or combined for application. In addition, in the following description and drawings, substantially the same or equivalent parts are marked with the same reference numerals for description.

[0044] Figure 1 1 is a diagram schematically showing an example of the internal structure of a lamp device 10 according to an embodiment of the present invention. The lamp device 10 is, for example, a headlamp mounted on a vehicle such as an automobile. Figure 1 The cross section along a horizontal plane (or a plane parallel to the road surface) when the lamp device 10 (left headlamp) is mounted on the left front side of the vehicle as viewed from above is schematically shown.

[0045] In the lamp device 10, a lamp housing (housing) is formed by a base 11 and a transparent cover 12 held by the base 11. A headlamp unit 14 as an illumination (light source) unit, a millimeter wave radar unit (radar device) 15, a light emitting unit 16, and at least one extension 19 are built into the lamp housing.

[0046] The headlamp unit 14 has a light source such as an LED (Light Emitting Diode) and a lens or a reflector for distributing and irradiating the light emitted by the light source. The headlamp unit 14 is arranged along an optical axis AX1 and irradiates a low beam (a beam for meeting vehicles) and a high beam (a beam for driving) irradiation light LB in the forward (FRONT) direction.

[0047] It should be noted that, in this specification, the lighting unit is not limited to a headlight light source, but also refers to a light source having the purpose and function of emitting light toward the outside, such as a taillight or a backlight.

[0048] The millimeter wave radar unit 15 has a transmitting antenna and a receiving antenna on its transmitting and receiving surface (electromagnetic wave radiating surface) 15S. The millimeter wave radar unit 15 radiates electromagnetic waves (millimeter waves) from the transmitting antenna, and receives reflected waves reflected by the object through the receiving antenna. The received signal is processed by a control device, such as an ECU (Electronic Control Unit) not shown in the figure, to detect the distance, angle, and speed to the object. In the millimeter wave radar unit 15, for example, millimeter waves in the 76-81 GHz frequency band, especially millimeter waves in the 79 GHz frequency band, are used, but it is not limited to this frequency band.

[0049] The normal direction AX2 of the antenna surface (electromagnetic wave radiating surface) 15S of the millimeter-wave radar unit 15 is configured to be inclined at an angle θ (45° in this embodiment) toward the outside direction of the vehicle (i.e., to the left in the case of a left headlight) relative to the optical axis AX1 of the headlight unit 14, thereby being able to detect the area from the front direction to the side direction.

[0050] The extension portion 19 is a design component provided to reflect light or to make internal structures and the like difficult to be visually recognized from the outside.

[0051] like Figure 1 As shown, the light emitting unit 16 includes a light source 17 and a light guide 18, and the light guide 18 is composed of at least one light guide member for guiding the light emitted by the light source 17. The light emitting unit 16 functions as a DRL (Daytime Running Lamps) or a turn signal. The light source 17 includes, for example, an LED, an incandescent bulb, etc., and supplies the light to the light guide 18.

[0052] Figure 2 1 is a perspective view showing the configuration of the millimeter wave radar unit 15 and the light emitting unit 16. In the present embodiment, the light source 17 is composed of two separate light sources 17A, and the light guide 18 has two light guide components 18A. Light is incident from each light source 17A to the corresponding light guide component 18A, and each light guide component 18A can be controlled to emit light or not emit light independently.

[0053] In addition, the light guide components 18A are each configured as a light guide plate having a parallel flat plate shape and a substantially constant layer thickness, and the surface is arranged parallel to the antenna surface (electromagnetic wave radiation surface) 15S of the millimeter wave radar unit 15. Alternatively, the light guide components 18A may be each configured as a light guide film having no flexibility (i.e., a component having a parallel flat plate shape and a substantially constant layer thickness).

[0054] The light guide member 18A is a member formed into a plate or film shape by a transparent resin such as polycarbonate, acrylic, epoxy resin, or boron imide, and radiates light input from the light source 17 at its end.

[0055] exist Figure 2 In the case shown, the two light guide members 18A extend in the horizontal direction (first direction) and are arranged at a distance from the antenna surface 15S. In addition, the two light guide members 18A are configured in the following manner: they are arranged at a distance from each other in the vertical direction (second direction) in a plane parallel to the antenna surface 15S (in the same plane), and cover a portion of the surface of the antenna surface 15S of the millimeter wave radar unit 15. It should be noted that the light guide 18 can be configured to cover a portion of the surface or the entire surface of the antenna surface 15S.

[0056] That is, the light guide 18 is composed of a plurality of light guide members extending in the horizontal direction (or vertical direction) and arranged at intervals in the vertical direction (or horizontal direction) in a plane parallel to the antenna surface 15S.

[0057] The plurality of light guide members 18A are arranged at intervals from each other in a plane parallel to the antenna plane 15S, thereby minimizing attenuation and reflection of radar waves and suppressing changes in electromagnetic wave radiation patterns.

[0058] Figure 3A 15S is a diagram showing a state where the light guide member 18A and the antenna surface 15S are viewed from the antenna surface 15S side of the millimeter wave radar unit 15. Figure 3B It is a diagram schematically showing a cross section of the millimeter wave radar unit 15 and the light guiding member 18A.

[0059] Figure 3A and Figure 3B Although the case where each light guide member 18A is individually connected to the light source 17A is shown, it is also possible to configure such that light is guided from one light source 17 to at least one light guide member 18A.

[0060] Figure 4The diagram schematically shows the situation where the millimeter wave MW (wavelength λ) emitted by the millimeter wave radar unit 15 passes through the light guide component 18A (thickness TG). A portion of the millimeter wave MW is reflected by the light guide component 18A (reflected wave WR), and the millimeter wave passing through the light guide component 18A is attenuated by the light guide component 18A and then radiated to the outside (transmitted millimeter wave WA).

[0061] [Reflection Loss, Transmission Loss, and Thickness of Light Guide Member 18A]

[0062] When the difference in dielectric constant between the light guide component and the air is large, the electromagnetic waves emitted from the millimeter wave band of the millimeter wave radar will be reflected by the light guide component (dielectric). In addition, due to the influence of the dielectric loss of the light guide component, the electromagnetic waves emitted by the millimeter wave radar are absorbed and converted into heat in the light guide component. Therefore, when the light guide component is arranged in front of the antenna surface of the millimeter wave radar, the intensity of the electromagnetic waves is reduced, or the radiation direction (antenna pattern) of the electromagnetic waves is changed due to the difference in dielectric constant between the light guide component and the air.

[0063] When the frequency used in the millimeter wave radar is set to f (Hz), the wavelength λ (m) in the space of the frequency is as follows.

[0064] λ=c / f(c is the speed of light, c=3.0×10 8 m / s)

[0065] For example, if the frequency f is 79 GHz, the wavelength λ is 3.8 mm. If the wavelength in the dielectric is λd and the relative dielectric constant of the dielectric is εr, the wavelength in the dielectric can be expressed by the following equation.

[0066] λd=λ / εr 1 / 2

[0067] Furthermore, when the wavelength in space is 3.8 mm and the relative dielectric constant of the dielectric is 2.4, the wavelength in the dielectric is 2.45 mm.

[0068] When the dielectric loss is assumed to be tan δ, the distance D (half-power depth) at which the power density of the irradiated electromagnetic wave is halved can be expressed by the following equation in the field of high-frequency heating.

[0069] D(m)=3.32×107 / (f×εr 1 / 2 ×tanδ)

[0070] For example, when an electromagnetic wave with a frequency of 79 GHz propagates in a dielectric with a relative permittivity of 2.4 and a dielectric loss of 0.06, its power is halved at a thickness of 4.5 mm.

[0071] Electromagnetic waves are absorbed by the dielectric and converted into heat, and the power is halved at a thickness of 4.5 mm. However, since there is also power reflected at the interface of the dielectric due to the difference in dielectric constant between air and dielectric, it can be expected that when the thickness of the dielectric is 4.5 mm, the power actually passing through the dielectric is attenuated by more than half.

[0072] According to the above example, by using a thin dielectric for the light-guiding component, the attenuation of electromagnetic waves when traveling in the dielectric can be suppressed. However, if the influence of reflected waves generated at the interface of the dielectric is taken into account, setting the thickness of the dielectric to n×λd / 2 (n is a natural number) can suppress the influence of reflected waves, and therefore this thickness is optimal.

[0073] In order to suppress reflected waves, a structure in which resins with different dielectric constants are stacked is used in antenna covers and the like. However, since the function of a light guide member to guide light is important, it is advantageous to use a light guide member composed of a single dielectric.

[0074] Therefore, the thickness of the dielectric is studied by considering the relationship between the reflection loss and the transmission loss of the power. It should be noted that the reflection loss and the transmission loss can be obtained using the waveguide S parameter method or the free space S parameter method.

[0075] The thickness of the dielectric is selected as follows. That is, when the thickness of the dielectric through which the electromagnetic wave passes is set to TG, when the reflection loss is greater than the transmission loss (reflection loss ≥ transmission loss), TG = n × λd / 2 (n is a natural number). It should be noted that when the thickness TG is set to an integer multiple of λd / 2, the transmission loss also increases, so it is preferred to use an integer value that satisfies reflection loss ≥ transmission loss.

[0076] In addition, when the reflection loss is smaller than the transmission loss (reflection loss<transmission loss), the thickness TG of the dielectric is smaller than λd / 2, that is, TG<λd / 2.

[0077] It should be noted that even if TG does not completely conform to n×λd / 2 (n is a natural number), the thickness can be set to a frequency band where the reflection loss of the success rate is, for example, -10dB or less (the reflection power is less than 10%) relative to the frequency f, and there will be no problem in practice. Such a range of thickness TG can be derived, for example, by using the S parameter method to set the reflection loss S 11 The value of becomes a conditional expression of -10 dB or less, and is derived by solving for the thickness TG.

[0078] (Formula 1)

[0079]

[0080] in,

[0081] (Formula 2)

[0082]

[0083] (Formula 3)

[0084] z=exp(-γ·TG)…(3)

[0085] (Formula 4)

[0086]

[0087] (Formula 5)

[0088]

[0089] Among them, (c air : Speed ​​of light in air, c vac : speed of light in vacuum, ω: angular frequency of electromagnetic waves (=2×π×f[Hz]), ε r : Complex dielectric constant of dielectric, λ c : Cut-off wavelength (the upper limit of the wavelength of fundamental mode propagation, which determines the minimum operating frequency of the transmission line).

[0090] The range of the allowable thickness TG can also be determined by evaluating the dependence of the reflection loss on the thickness TG through experiments to determine an appropriate value (for example, a value where the reflection loss is -10 dB or less). It should be noted that when the reflection loss is -10 dB or more, the device may fail.

[0091] Note that, although the case where the light guide member 18A is composed of a single dielectric has been described, when the light guide member 18A is composed of a plurality of single dielectric layers, the relative dielectric constant and dielectric loss may be replaced with effective values ​​and applied.

[0092] [Thermal Noise]

[0093] like Figure 3A As shown, by setting the interval DG between the light source 17A and the antenna surface 15S to be more than 10 times the wavelength (λ) of the electromagnetic wave emitted by the millimeter-wave radar unit 15, the thermal noise generated from the heating part of the light source 17 (LED, incandescent lamp, etc.) can be suppressed from being emitted from the light guiding component 18B toward the antenna of the millimeter-wave radar unit 15.

[0094] Figure 5It is a stereoscopic diagram showing a modified example of the structure of the millimeter wave radar unit 15, the light source 17A of the light emitting unit 16, and the light guide component 18A. In this modified example, the electromagnetic wave absorber 21 that absorbs the thermal noise emitted from the light source 17 is arranged between the light source 17A and the antenna surface 15S. That is, the electromagnetic wave absorber 21 is arranged at the end of the light guide component 18A on the side of the light source 17A. Preferably, the electromagnetic wave absorber 21 surrounds the light guide component 18A and / or is connected to (closely attached to) the light guide component 18A.

[0095] Since the structure is adopted to attenuate the thermal noise radiation in the radar frequency band in the light guide (light guide component 18A), the receiving sensitivity of the millimeter wave radar will not be deteriorated. The electromagnetic wave absorber 21 can avoid the influence of the thermal noise emitted by the light source 17, and can suppress the reduction of the receiving sensitivity of the radar, so as to perform high-precision radar sensing.

[0096] As the electromagnetic wave absorber 21 , a material obtained by mixing an electromagnetic wave absorbing material such as ferrite or carbon into a resin or paint, or a known material such as ceramics can be used.

[0097] [Examples of Modifications of Light Guide]

[0098] Figure 6 In a modified example of the above embodiment, the light guide 18 includes a light guide component 18A and a light guide component 18B which are different from each other. The light guide component 18A is the same as the above light guide component and is a parallel flat plate light guide. The light guide component 18B is configured as a curved light guide with a constant layer thickness. For example, the light guide component 18A is formed to be curved only in a direction (vertical direction) perpendicular to the extension direction (horizontal direction). Therefore, when viewed from the front, the light guide component 18A is curved in a direction (vertical direction) perpendicular to the extension direction (horizontal direction). Figure 3A same.

[0099] Thus, the light guide 18 is composed of a plurality of light guide components, at least one of which is a curved light guide having a constant layer thickness, and the plurality of light guide components are arranged at intervals from each other in a plane parallel to the antenna surface 15S. That is, the curved light guide is curved only in the vertical direction, and the extending direction is parallel to the antenna surface 15S.

[0100] The parallel flat plate-shaped light guide component 18A is a preferred method in terms of suppressing the reflection of radar waves. On the other hand, the curved light guide component 18B preferably forms a light distribution required by law in terms of diffuse radiation of light, and is preferably used as a DRL (Daytime Running Lamps) or a turn signal. However, the parallel flat plate-shaped light guide component 18A and the curved light guide component 18B can be used in appropriate combination according to the purpose and function. In addition, the multiple light guide components constituting the light guide body 18 can also have different sizes and shapes.

[0101] Fig. 7A In a further modification of the above embodiment, the light guide 18 has at least one light guide member 18C. Fig. 7A In the embodiment, the light guide 18 has two light guide components 18C. Figure 2 The light guide member 18A shown in the figure is provided in the same shape and arrangement.

[0102] Figure 7B 15 is an enlarged cross-sectional view showing an enlarged cross section of the light guide member 18C. The light guide member 18C includes the light guide member 18A provided on the antenna surface 15S side and the light diffusion member 23 provided on the light guide member 18A.

[0103] The light diffusion component 23 is made of foamed resin. The foamed resin is formed by sealing carbon dioxide gas or the like in a transparent resin such as polycarbonate, acrylic acid, boron amide, epoxy resin, etc., and then forming bubbles in the resin. Since the gas is sealed in the resin, the dielectric constant can be reduced and the influence on electromagnetic waves can be greatly reduced. When the foaming ratio of the foamed resin is more than twice, the influence of the resin can be almost ignored.

[0104] The light guide member 18A (thickness TG) is the same as the above-mentioned light guide member. When the reflection loss of the light guide member 18A is greater than the transmission loss (reflection loss ≥ transmission loss), TG = n × λd / 2 (n is a natural number). In addition, when the reflection loss is less than the transmission loss (reflection loss < transmission loss), the light guide member 18A has a layer thickness that satisfies TG < λd / 2.

[0105] Fig. 8A 1 is a diagram schematically showing the arrangement structure of the millimeter wave radar unit 15, the light guide member 18D, and the transparent cover 12 in another embodiment of the present invention. Fig. 8A The diagram is a view of the millimeter wave radar unit 15 as viewed from the front side (vertical direction) of the antenna surface (radar wave radiating surface) 15S of the transmitting and receiving antenna 15A.

[0106] Figure 8B It is a schematic representation of Fig. 8A A cross-sectional view of the configuration structure of the millimeter wave radar unit 15, the light guide component 18D, and the transparent cover 12 observed along the WW line.

[0107] like Figure 8B As shown, a parallel flat plate-shaped light guide member 18D is disposed at a constant interval C2 in front of the antenna surface 15S of the millimeter wave radar unit 15. The light guide member 18D has a thickness TG.

[0108] For example, the light guide member 18D is formed as a parallel flat plate with a substantially constant thickness, and both surfaces are arranged parallel to the antenna surface 15S of the millimeter wave radar unit 15. The light guide member 18D is formed into a plate by, for example, forming a transparent resin such as polycarbonate, acrylic, epoxy resin, or boron imide.

[0109] In addition, the light guide member 18D and the millimeter wave radar unit 15 are arranged in such a manner that the interval between the light guide member 18D and the transparent cover 12 is a constant interval C1. The transparent cover 12 is formed as a cover having light transmittance to light, such as a transparent resin. It should be noted that the transparent cover 12 only needs to be light transmittance, and may also be a cover member having translucency such as color.

[0110] The transparent cover 12 may have a curved shape as a whole, or may have portions with different thicknesses. However, when viewed from a direction perpendicular to the antenna surface 15S (hereinafter, also referred to as a vertical view), the region of the transparent cover 12 (hereinafter, also referred to as a radiation surface corresponding region) 12S overlapping the antenna surface 15S (electromagnetic wave radiation surface) preferably has a parallel flat plate shape with a constant thickness.

[0111] like Fig. 8A As shown, the light guide member 18D is optically connected at its end to the light source 17. Light from the light source 17 is incident on the light guide member 18D, and the light guide member 18D can be controlled to emit light or not emit light.

[0112] The light guide member 18D is configured to have a size and an arrangement so as to cover the entire antenna surface 15S of the millimeter wave radar unit 15 when viewed from a direction perpendicular to the antenna surface 15S.

[0113] like Fig. 8A and Figure 8B As shown, the front region 12S of the transparent cover 12, the light guide member 18D, and the antenna surface 15S are arranged parallel to each other.

[0114] The transparent cover 12 is preferably configured to have a size and an arrangement such that a region 12S of the transparent cover 12 overlapping the antenna surface 15S (region corresponding to the radiation surface) covers the entire antenna surface 15S when viewed from a direction perpendicular to the antenna surface 15S.

[0115] [Interval and Thickness of Light Guide Component and Transparent Cover 12]

[0116] As described above, the light-guiding component 18D and the transparent cover 12 arranged on the front surface side (antenna surface 15S side) of the millimeter-wave radar unit 15 are, for example, components made of resin, and the difference in dielectric constant between the resin and the air at the interface between the resin and the space causes reflection of electromagnetic waves.

[0117] At this time, when the phase of the transmitted electromagnetic wave and the phase of the reflected electromagnetic wave are in directions to cancel each other out, attenuation occurs due to the synthesis of the transmitted electromagnetic wave and the reflected electromagnetic wave.

[0118] More specifically, in this specification, the frequency f of the millimeter wave radar is, for example, 76 GHz to 81 GHz. When the frequency f (Hz) is, for example, 76 GHz, the wavelength λ (in air) is 3.8 mm.

[0119] For example, when the relative dielectric constant εr1 of the transparent cover 12 (dielectric) is 2.4, the wavelength λd in the transparent cover 12 is 2.45 mm, and when the relative dielectric constant εr2 of the light guide member 18D is 2.8, the wavelength λd in the light guide member 18D is 2.27 mm.

[0120] When the thickness of the radiation surface corresponding region 12S of the transparent cover 12 is set to TK, the relative dielectric constant is set to εr1, the wavelength (effective wavelength) in the resin (medium) is set to λd1, and the thickness of the light guide member 18D is set to TG, the relative dielectric constant is set to εr2, and the effective wavelength in the resin (medium) is set to λd2, the radiation surface corresponding region 12S of the transparent cover 12, the light guide member 18D, and the antenna surface 15S of the millimeter wave radar unit 15 are set in a manner that satisfies the following relationship. It should be noted that in the following formula, C1 is the interval between the radiation surface corresponding region 12S and the light guide member 18D, C2 is the interval between the light guide member 18D and the antenna surface 15S (electromagnetic wave radiation surface), and n1, n2, m1, and m2 are natural numbers.

[0121] TK=n1×λd1 / 2

[0122] TG=n2×λd2 / 2

[0123] C1=m1×λ / 2

[0124] C2=m2×λ / 2

[0125] Therefore, by appropriately selecting the thickness TK of the radiation surface corresponding area 12S and the thickness TG of the light guide member 18D, the reflection loss of electromagnetic waves caused at the interface between the transparent cover 12 and the space and the interface between the light guide member 18D and the space can be reduced. That is, not only the multiple reflections between the light guide member 18D and the antenna surface 15S (electromagnetic wave radiation surface) can be suppressed, but also the multiple reflections between the radiation surface corresponding area 12S of the transparent cover 12 and the light guide member 18D can be suppressed. Therefore, their synergy multiple reflections can be effectively suppressed. In addition, the change of the electromagnetic wave radiation pattern can be reduced.

[0126] That is, as described above, according to the lamp device of this embodiment, it is possible to solve the problem that the reflected electromagnetic waves between the transparent cover 12 and the light guide member 18D are further multi-reflected between the transparent cover 12 and the light guide member 18D to increase noise.

[0127] In addition, it is possible to solve the problem that the reflected electromagnetic waves that have mistakenly entered the space between the transparent cover 12 and the light guide member 18D are multiply reflected between the transparent cover 12 and the light guide member 18D, thereby increasing noise.

[0128] It should be noted that when the thicknesses TK and TG are increased, the transmission loss increases due to the dielectric loss tangent of the resin. Therefore, it is preferable that the thickness TK is set to n1=2 to 4 and the thickness TG is set to n2=2 or 3.

[0129] In addition, the radiation surface corresponding area 12S of the transparent cover 12 and the light guide member 18D may be slightly bent due to vibration during mounting and environmental temperature. Although the transmission characteristics and reflection characteristics may change slightly due to the bending, in order to suppress the average characteristic change of the entire surface of the radiation surface corresponding area 12S and the light guide member 18D, it is preferred that the interval C1 and the interval C2 should not be too small. It should be noted that since both the radiation surface corresponding area 12S and the light guide member 18D can be bent, it is preferred that the interval C1 is larger than the interval C2 (m1>m2).

[0130] In addition, in the spaces between the intervals C1 and C2, reflected electromagnetic waves from other components (such as the extension) in the lamp device may cause stray noise. Therefore, it is preferred that the intervals C1 and C2 are not too large.

[0131] Taking the above into consideration, it is preferred that m1≥4 and m2≥2, and more preferably 4≤m1≤8 and 2≤m2≤4.

[0132] Even if TK, TG, C1, and C2 do not completely satisfy the above relationship, multiple reflections can be suppressed extremely efficiently by setting them so that the power reflection loss becomes a frequency band of -10 dB or less (reflected power is less than 10%) with respect to the frequency f.

[0133] The above ranges of TK, TG, C1, and C2 can be derived, for example, by using the above-mentioned S parameter method to set the reflection loss S 11The value of is -10dB or less, and then derived by solving TK, TG, C1, and C2. TK and TG can be calculated by referring to the dielectric constant of each material, and C1 and C2 can be calculated by referring to the dielectric constant of air. In addition, the dependence of reflection loss on TK, TG, C1, and C2 can be evaluated through experiments, and appropriate values ​​(for example, values ​​such as reflection loss of -10dB or less) can be determined.

[0134] As described in detail above, it is possible to provide a light emitting unit and a lamp device that suppress attenuation and reflection of radar waves caused by a light guide (light guide member) and do not change the electromagnetic wave radiation pattern without causing a loss of radar function.

[0135] In addition, it is possible to provide a light emitting unit and a lamp device capable of suppressing a decrease in the receiving sensitivity of a radar due to thermal noise of a light source that supplies light to a light guide.

[0136] Explanation of symbols

[0137] 10: lighting device, 11: base body, 12: transparent cover, 12S: radiation surface corresponding area, 14: front lighting unit, 15: millimeter wave radar unit, 15S: antenna surface, 16: light emitting unit, 17, 17A: light source, 18: light guide, 18A, 18B, 18C: light guiding component, 18D: light guiding component, 19: extension part, 21: electromagnetic wave absorber, 23: light diffusion component (foamed resin).

Claims

1. A lighting device comprising a lighting unit and a radar device, The lamp device is characterized in that It also has: a light guide that covers at least a portion of the electromagnetic wave radiating surface of the radar device, and a light source that supplies light to the light guide, When the thickness of the light guide is TG and the wavelength of the electromagnetic wave emitted by the radar device in the light guide is λd, TG is set as follows: when the reflection loss of the light guide with respect to the electromagnetic wave is less than the transmission loss, TG<λd / 2 is satisfied; when the reflection loss is greater than the transmission loss, the reflection loss is made less than -10 dB, The light guide is composed of a plurality of light guide components. The plurality of light guide members are arranged to extend in the horizontal direction and to be spaced apart from each other in the vertical direction in a plane parallel to the electromagnetic wave radiation plane of the radar device, or The plurality of light guide members are arranged so as to extend in the vertical direction and to be spaced apart from each other in the horizontal direction within a plane parallel to the electromagnetic wave radiation plane of the radar device.

2. The lamp device according to claim 1, characterized in that At least one of the plurality of light guide components is configured as a curved light guide having a constant layer thickness. The plurality of light guide members are arranged in parallel with each other at intervals in a plane parallel to an electromagnetic wave radiation plane of the radar device.

3. The lamp device according to claim 1 or 2, characterized in that: The distance between the light source and the electromagnetic wave radiating surface of the radar device is at least 10 times the wavelength of the radiated electromagnetic wave.

4. The lamp device according to claim 1 or 2, characterized in that: The light guide has an electromagnetic wave absorber provided between the light source and an electromagnetic wave radiating surface of the radar device.

5. The lamp device according to claim 1 or 2, characterized in that: A light diffusion member made of foamed resin is provided on the light guide.

6. A light emitting unit, characterized in that: have: a light guide disposed in front of an electromagnetic wave radiating surface of the radar device and configured to cover at least a portion of the electromagnetic wave radiating surface, and a light source that supplies light to the light guide, When the thickness of the light guide is TG and the wavelength of the electromagnetic wave emitted by the radar device in the light guide is λd, TG is set as follows: when the reflection loss of the light guide with respect to the electromagnetic wave is greater than the transmission loss, TG=n×λd / 2 is satisfied, where n is a natural number; when the reflection loss is greater than the transmission loss, the reflection loss is made less than -10 dB, The light guide has an electromagnetic wave absorber provided at an end portion on a side of the light source.

7. The light emitting unit according to claim 6, characterized in that: A foamed resin material is disposed on the light guide.

8. The light emitting unit according to claim 6, characterized in that: The light guide is composed of a plurality of light guide components. The plurality of light guide members are arranged to extend in a first direction within the same plane and to be spaced apart from each other in a second direction perpendicular to the first direction.

9. The light emitting unit according to claim 8, characterized in that: A foamed resin material is disposed on the light guide.

10. A lamp device comprising a lighting unit, a radar device for radiating electromagnetic waves, and a light-transmitting cover, wherein: The invention further comprises: a light guide disposed between the light-transmitting cover and the electromagnetic wave radiating surface of the radar device and covering at least a portion of the electromagnetic wave radiating surface of the radar device; and a light source that supplies light to the light guide, When viewed from a direction perpendicular to the electromagnetic wave radiating surface, the area of ​​the light-transmitting cover overlapping the electromagnetic wave radiating surface, i.e., the area corresponding to the radiating surface, the light guide, and the electromagnetic wave radiating surface are arranged in parallel with each other. The radiation surface corresponding area of ​​the light-transmitting cover and the light guide are configured in such a manner that they have the following size and configuration: when viewed from a direction perpendicular to the electromagnetic wave radiation surface, the radiation surface corresponding area and the light guide cover the entire surface of the electromagnetic wave radiation surface. The thickness TK of the region corresponding to the radiation surface of the light-transmitting cover is set so that the reflection loss of the electromagnetic wave incident on the region corresponding to the radiation surface of the light-transmitting cover is -10 dB or less. The thickness TG of the light guide is set so that the reflection loss of the electromagnetic wave incident on the light guide is less than -10 dB. The interval C1 between the radiation surface corresponding area and the light guide is set so that the reflection loss of the electromagnetic wave incident on the radiation surface corresponding area and the light guide is less than -10 dB. The interval C2 between the light guide and the electromagnetic wave radiating surface is set so that the reflection loss of the electromagnetic wave incident on the light guide from the space between the light guide and the electromagnetic wave radiating surface is less than -10 dB. When the wavelength of the electromagnetic wave in space is set to λ, the effective wavelength in the region corresponding to the radiation surface is set to λd1, and the effective wavelength in the light guide is set to λd2, the region corresponding to the radiation surface, the light guide, and the electromagnetic wave radiation surface are set so that TK, TG, C1, and C2 satisfy the following relationship, wherein, n1, n2, m1, m2 are natural numbers, TK=n1×λd1 / 2 TG=n2×λd2 / 2 C1=m1×λ / 2 C2=m2×λ / 2.

11. The lamp device according to claim 10, characterized in that The n1 satisfies n1=2-4, and the n2 satisfies n2=2 or 3.

12. The lamp device according to claim 10 or 11, characterized in that The m1 and m2 satisfy m1≥4, m2≥2.

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