Vehicle lamp

Abstract

Provided is a vehicle lamp capable of suppressing a decrease in detection accuracy in cases in which a radio wave emission means is disposed so as to overlap an optical member having a structure that forms a light-emitting surface using the reflective surfaces of prisms.　This vehicle lamp (1) comprises: a radar device (21) that emits radio waves forwards; an optical member (23) that is provided overlapping a radio wave emission area (RA) of the radar device (21), has a plurality of prisms (P) on at least the rear surface (23d), said prisms being composed of reflective surfaces (Pa) that take light introduced thereto from a light source (25) and reflect said light forwards, and forms a light-emitting surface (LS) using the reflective surfaces (Pa) of the plurality of prisms (P); and a lens (26) that is provided to the front of the optical member (23) and emits light introduced from the optical member (23) forwards. In the optical member (23), the light-emitting surface (LS) overlaps with the radio wave emission area (RA), and the pitch (p) and the height (h) of at least the plurality of prisms (P) inside the radio wave emission area (RA) are 0.43 mm or less.

Description

Vehicle lighting fixtures

[0001] The present disclosure relates to a vehicle lamp.

[0002] A radar device is known that emits radio waves, such as microwaves or millimeter waves, outside a vehicle and uses the reflected waves to determine the distance to an obstacle, etc. The radar device is provided with a cover that transmits radio waves on the radio wave emitting side. The cover reflects a portion of the radio waves from its back surface, and the reflected waves are received by the radar device. As a result, the detection accuracy of the radar device is reduced by the waves reflected by the cover. To address this, a cover with an uneven back surface has been proposed (see, for example, Patent Document 1). This cover utilizes the fact that radio waves are diffused by the uneven structure. The radio waves emitted by the radar device are reflected in a diffused state by the back surface of the cover. Therefore, the cover reduces the amount of radio waves received by the radar device through reflection from the back surface, thereby preventing a decrease in detection accuracy.

[0003] JP 2019-110428 A

[0004] The present inventors have been researching a vehicle lamp having an optical element. The optical element includes a prism and introduces light from a light source. The optical element uses reflection from the reflective surface of the prism to emit the light introduced from the light source toward the outside of the vehicle. Furthermore, the present inventors have discovered that it is possible to reduce installation space by arranging the radar device and the optical element in an overlapping manner. However, since the optical element reflects light to form a light-emitting surface, the prism cannot be removed. Therefore, if the optical element is overlapped on the radio wave emitting side of the radar device, the radio waves from the radar device will be reflected by the prism, resulting in a decrease in detection accuracy.

[0005] The present disclosure has been made to solve such conventional problems, and its purpose is to provide a vehicle lamp that can suppress a decrease in detection accuracy when an optical element having a structure that forms a light-emitting surface using the reflective surface of a prism and a radio wave emitting means are arranged in an overlapping manner.

[0006] The vehicle lamp according to the present disclosure comprises: a radio wave emitting means for emitting radio waves in a predetermined direction; an optical element that is arranged so as to overlap a radio wave emitting area on the side of the radio wave emitting means in the predetermined direction, and that has a plurality of prisms on at least a surface opposite the predetermined direction, the prisms having a reflective surface that introduces light from a light source from a direction intersecting the predetermined direction and reflects it toward the predetermined direction, the reflective surfaces of the plurality of prisms forming a light-emitting surface; and a lens element that is arranged on the side of the optical element in the predetermined direction and introduces light from the optical element and emits it in the predetermined direction, the optical element having the radio wave emitting area and the light-emitting surface overlapping, and the pitch and height of the plurality of prisms at least within the radio wave emitting area being 0.43 mm or less.

[0007] According to the present disclosure, it is possible to provide a vehicle lamp that can suppress a decrease in detection accuracy when an optical element having a structure that forms a light-emitting surface using the reflective surface of a prism and a radio wave emitting means are arranged in an overlapping manner.

[0008] FIG. 1 is a side cross-sectional view showing a vehicle lamp according to a first embodiment. FIG. 2 is an exploded perspective view showing a partial configuration of FIG. 1. FIG. 3A is a configuration diagram showing a partial configuration of the radar device shown in FIG. 2, and is a top cross-sectional view. FIG. 3B is a configuration diagram showing a partial configuration of the radar device shown in FIG. 2, and is a partial enlarged view of FIG. 3A. FIG. 4A is a configuration diagram showing a partial configuration of a radar device according to a second embodiment, and is a top cross-sectional view. FIG. 4B is a configuration diagram showing a partial configuration of the radar device according to the second embodiment, and is a partial enlarged view of FIG. 4A. FIG. 5 is a cross-sectional view showing a modified example of a plurality of prisms.

[0009] Vehicle lighting devices according to embodiments of the present disclosure will be described below, but the present disclosure is not limited to the following embodiments and can be modified as appropriate without departing from the spirit of the present disclosure. Furthermore, in the embodiments, some configurations are omitted from illustration and description, but it goes without saying that publicly known or well-known technologies are applied as appropriate to the details of the omitted technologies within the scope of the content described below.

[0010] Fig. 1 is a side cross-sectional view showing a vehicle lamp according to a first embodiment, and Fig. 2 is an exploded perspective view showing a portion of the configuration of Fig. 1. The vehicle lamp 1 shown in Fig. 1 is installed, for example, near the center of the front of a vehicle. The vehicle lamp 1 includes a case 10, a radar irradiation unit 20, and an outer lens 30.

[0011] The case 10 is a member that houses each element, such as the radar irradiation unit 20. The case 10 has an opening O on the light emission side. The opening O of the case 10 is configured to be closed by an outer lens 30. The outer lens 30 is configured, for example, by a clear lens.

[0012] As shown in FIG. 2 , the radar irradiation unit 20 includes a radar device (radio wave emission means) 21, a housing 22, an optical member 23, a light guide member 24, a light source 25, a lens (lens member) 26, and a mask (pattern forming unit) 27.

[0013] The radar device 21 emits millimeter waves, a type of radio wave, forward (in a predetermined direction). The radar device 21 also receives reflected waves that are the emitted millimeter waves reflected by obstacles and returned. The radar device 21 includes a calculation unit (not shown). The calculation unit detects the situation around the vehicle, for example, by measuring the received reflected waves to determine the distance to the obstacle. Note that the calculation unit is not limited to being provided within the radar device 21, and may be configured by a CPU (Central Processing Unit) or the like external to the radar device 21.

[0014] The radar device 21 is configured to emit radio waves with a predetermined directivity, so that a radio wave emission area (see symbol RA in FIG. 3A described later) is formed in front of the radar device 21, which is the radio wave emission side.

[0015] The housing 22 is a support member that supports the optical member 23. The optical member 23 emits light forward. The optical member 23 includes a rectangular plate 23a and a circular portion 23b that is provided so as to roughly surround the rectangular plate 23a. Light introduction portions 23c are formed on both sides of the circular portion 23b. A light guide member 24 is optically connected to the introduction portion 23c. In FIG. 2, the light guide member 24 is separated from the introduction portion 23c, but they may be in contact with each other. The light guide member 24 may also be integrated with the optical member 23. A light source 25 is provided near the end of the light guide member 24 that is opposite the introduction portion 23c. Light from the light source 25 is guided from the introduction portion 23c through the light guide member 24 into the optical member 23.

[0016] Since the housing 22 supports the optical member 23 having such a shape, it is formed, for example, from a circular plate. Note that the introduction portion 23c is not limited to being provided on both sides, but may be provided on only one side. Also, the introduction portion 23c may be provided on the top or bottom. Furthermore, the introduction portion 23c may introduce light from a direction intersecting the front-to-rear direction, or may introduce light from a slightly oblique direction. In addition, the number of introduction portions 23c is not limited to two, but may be one or three or more.

[0017] Fig. 3A is a top cross-sectional view showing a partial configuration of the radar device 21 shown in Fig. 2. Fig. 3B is a partial enlarged view of Fig. 3A showing a partial configuration of the radar device 21 shown in Fig. 2. As shown in Fig. 3A, in the first embodiment, the optical member 23 is provided so that at least a portion thereof overlaps with the radio wave emission area RA. Note that in the first embodiment, the light source 25 (see Fig. 2) is preferably located outside the radio wave emission area RA, and introduces light into the optical member 23 via the light-guiding member 24 (see Fig. 2).

[0018] The optical member 23 also has a plurality of prisms P on its rear surface (surface opposite to the predetermined direction) 23d. As shown in FIG. 3B , the plurality of prisms P have, for example, a triangular cross section. However, the plurality of prisms P are not limited to a triangular cross section and may have other shapes, such as an arc-shaped cross section. The optical member 23 reflects the introduced light forward by the reflective surfaces Pa of the plurality of prisms P. The reflective surfaces Pa of the plurality of prisms P of the optical member 23 form a light-emitting surface LS, allowing pedestrians and others in front of the vehicle to see the light-emitting state.

[0019] The lens 26 shown in Fig. 2 is provided in front of the optical member 23 and receives light from the optical member 23 and emits it forward. This lens 26 is configured, for example, as a clear lens, similar to the outer lens 30 (see Fig. 1). Note that, although the lens 26 is a separate member from the outer lens 30 in the first embodiment, this is not particularly limited. The lens 26 of the vehicle lamp 1 may itself be configured as an outer lens.

[0020] The mask 27 is provided behind the lens 26. The mask 27 partially blocks light reflected by the prisms P of the optical member 23, thereby illuminating the light with a predetermined pattern. The pattern includes not only figures and patterns but also character strings. The lens 26 has a concave shape with an open rear. Therefore, the mask 27 is provided to fit into the recess of the lens 26. The mask 27 may also be provided outside the recess. The mask 27 may be a member having a certain thickness or a thin plate-like member. The mask 27 may block light using a black portion with high light absorption, or may block light by utilizing reflection from a silver portion with high light reflectivity. Furthermore, although the mask 27 is provided behind the lens 26 in the first embodiment, this is not a limitation, and the mask 27 may also be provided in front of the lens 26 or even in front of the outer lens 30. The mask 27 may also be formed integrally with the lens 26 by coating the lens 26 with paint or vapor deposition.

[0021] The radar irradiation unit 20 as described above can emit radio waves using the light-emitting surface LS of the optical member 23 while emitting radio waves from the radar device 21. However, because the light-emitting surface LS of the optical member 23 overlaps with the radio wave emission area RA, the radio waves are reflected and refracted by the multiple prisms P, which reduces the detection accuracy of the radar device 21.

[0022] Therefore, in the optical member 23 shown in Figures 2, 3A, and 3B, the pitch p and height h of the multiple prisms P are set to 0.43 mm or less, at least within the radio wave emission area RA. Here, pitch p indicates the distance between adjacent prisms P, and refers to the distance between the same points of a specific prism P and its nearest neighboring prism P. Height h refers to the difference between the forward-most point and the rearward-most point of the prism P. By setting the pitch p and height h of the multiple prisms P to 0.43 mm or less, the multiple prisms P are less likely to reflect and refract radio waves. This allows the vehicular lamp 1 to suppress a decrease in the detection accuracy of the radar device 21.

[0023] This is based on the following theory. First, the center frequency of radio waves emitted by the vehicle radar device 21 is set to 77 GHz. The present inventors discovered that by configuring the multiple prisms P with a pitch p and height h that are equal to or less than the value obtained by multiplying the speed of light by a subwavelength of the radio wave wavelength, the radio waves are less likely to be reflected. Specifically, the wavelength of a 77 GHz frequency is 1 / 77 G, and the subwavelength is 1 / 10 of that, or 1 / 770 G. Since the speed of light is 299,792,458 km per second, 299,792,458 km × (1 / 770 G) ≈ 0.39 mm. Therefore, when 77 GHz radio waves are irradiated onto the multiple prisms P with a pitch p and height h of 0.39 mm or less, the radio waves pass through the multiple prisms P with almost no reflection or refraction. Furthermore, given that the center frequency of the radio waves is 77 GHz, the frequency of the radio waves radiated by the radar device 21 is considered to be in the range of approximately 70 GHz to 85 GHz. Therefore, by setting the pitch p and height h of the multiple prisms P to 0.43 mm or less, the radio waves are less likely to be reflected and refracted, and a decrease in detection accuracy can be suppressed. Note that if the width of the radio waves radiated by the radar device 21 is narrower, for example, 76 GHz to 78 GHz, the pitch p and height h of the multiple prisms P are preferably 0.395 mm or less.

[0024] Furthermore, in the first embodiment, the optical member 23 is configured to introduce light from both sides. When light is introduced from the left side, the light is guided from left to right. In the optical member 23, the right surface S1 of the multiple prisms P, which is the surface facing the light guide direction, serves as the reflective surface Pa. Similarly, the optical member 23 also introduces light from the right side. In this case, the light is guided from right to left, and the left surface S2 of the multiple prisms P, which is the surface facing the light guide direction, serves as the reflective surface Pa.

[0025] Here, it is preferable that the angle θ of the reflective surface Pa with respect to a plane perpendicular to the front-to-rear direction in a cross section along the light guide direction is 50° or less, because this makes it easier for light from the light guide direction to be reflected forward, thereby increasing the reflection efficiency.

[0026] Furthermore, in the first embodiment, it is preferable that the height h of the plurality of prisms P is equal to or less than the pitch p. This also makes it possible to reduce the angle θ and increase the reflection efficiency of light from the light guide direction.

[0027] Next, the operation of the vehicle lamp 1 according to the first embodiment will be described. First, in the vehicle lamp 1 according to the first embodiment, light is emitted from the light source 25. The light from the light source 25 passes through the light-guiding member 24 and is introduced into the optical member 23 from the introduction portion 23c.

[0028] Light introduced into the optical member 23 is incident on a plurality of prisms P formed on the rear surface 23d of the optical member 23. In the plurality of prisms P, surfaces S1 and S2 directly facing the light guide direction function as reflecting surfaces Pa. In particular, when the angle θ of the reflecting surfaces Pa of the plurality of prisms P is 50° or less and the height h is equal to or less than the pitch p, the introduced light is efficiently reflected forward.

[0029] The light reflected by the multiple prisms P reaches the mask 27. A portion of the light that reaches the mask 27 is cut off and emitted outside the vehicle through the lens 26 and the outer lens 30. As a result, a viewer recognizes the light in the shape cut off by the mask 27. For example, if the mask 27 is formed in the shape of an emblem, a viewer will recognize the emblem in a glowing state.

[0030] The radar device 21 emits millimeter waves toward the front of the vehicle. An optical member 23 is located within a radio wave radiation area RA of the millimeter waves. Among the multiple prisms P of the optical member 23, at least those within the radio wave radiation area RA are formed with a pitch p and a height h of 0.43 mm or less.

[0031] Therefore, the millimeter waves from the radar device 21 are less likely to be reflected and refracted by the plurality of prisms P. As a result, the deterioration of the detection accuracy of the radar device 21 is suppressed.

[0032] Thus, in the vehicular lamp 1 according to the first embodiment, the optical element 23 has a pitch p and height h of the prisms P of 0.43 mm or less, at least within the radio wave emission area RA. The radar device 21 used in a vehicle emits radio waves centered at approximately 77 GHz. The inventors discovered that by configuring the prisms P with a pitch p and height h equal to or less than the value obtained by multiplying the speed of light by a subwavelength of the radio wave wavelength, the radio waves from the radar device 21 are less likely to be reflected and are properly transmitted through the optical element 23. Therefore, the vehicular lamp 1 can suppress a decrease in detection accuracy when the radar device 21 is arranged overlapping the optical element 23, which has a structure in which the light-emitting surface LS is formed using the reflecting surface Pa of the prisms P.

[0033] The vehicle lamp 1 further includes a mask 27 for partially cutting the light from the multiple prisms P to illuminate the vehicle with a predetermined pattern. This allows for the creation of highly decorative designs such as manufacturer emblems, depending on the shape of the mask 27. As a result, the vehicle lamp 1 can suppress a decrease in detection accuracy while maintaining a highly decorative light-emitting form.

[0034] Furthermore, in the vehicle lamp 1, the light source 25 is located outside the radio wave radiation area RA and introduces light to the optical member 23 via the light-guiding member 24. Therefore, in the vehicle lamp 1, the presence of the light source 25 is less likely to affect the radiation of radio waves.

[0035] The optical member 23 has surfaces S1 and S2 directly facing the light guide direction as reflecting surfaces Pa of the plurality of prisms P. The angle θ of the reflecting surfaces Pa is set to 50° or less. Therefore, the vehicle lamp 1 can increase the light reflection efficiency of the plurality of prisms P.

[0036] Furthermore, the height h of the plurality of prisms P is set to be equal to or less than the pitch p. Therefore, the reflective surfaces Pa of the plurality of prisms P have a more acute angle. Therefore, the vehicle lamp 1 can improve the light reflection efficiency of the plurality of prisms P.

[0037] Next, a second embodiment of the present disclosure will be described. The vehicle lamp according to the second embodiment is similar to that of the first embodiment, but has a partial configuration different therefrom. The differences from the first embodiment will be described below.

[0038] FIG. 4A is a top cross-sectional view showing a partial configuration of the radar device 21 according to the second embodiment. FIG. 4B is a partial enlarged view of FIG. 4A showing a partial configuration of the radar device 21 according to the second embodiment. As shown in FIGS. 4A and 4B , the optical member 23 includes a plurality of second prisms P2 on the front surface (the surface facing the predetermined direction) 23e. The plurality of second prisms P2 are similar to the plurality of prisms P. The plurality of second prisms P2 reflect light from the light source 25 (see FIG. 2) backward by the reflecting surface Pb. Furthermore, the plurality of second prisms P2 have a pitch p2 and a height h2 of 0.43 mm or less at least within the radio wave emission area RA.

[0039] The reason why the pitch p2 and height h2 of the multiple second prisms P2 are 0.43 mm or less is the same as the reason why the pitch p and height h of the multiple prisms P are 0.43 mm or less. Furthermore, the pitch p2 and height h2 of the multiple second prisms P2 are preferably 0.395 mm or less. Furthermore, the multiple second prisms P2 have a surface directly facing the light guide direction as a reflecting surface Pb of the second prism P2. Furthermore, it is preferable that the angle θ2 between the reflecting surface Pb and a plane perpendicular to the front-to-rear direction in a cross section along the light guide direction is 50° or less. Additionally, it is preferable that the height h2 of the multiple second prisms P2 be equal to or less than the pitch p2.

[0040] The optical member 23, which includes a plurality of second prisms P2, reflects light from the light source 25 backward. A housing 22 (see FIG. 2) is provided behind the optical member 23. Therefore, the optical member 23 according to the second embodiment illuminates the housing 22. Therefore, if the housing 22 is made of a material or color with high reflectivity, such as white, the reflected light from the housing 22 can be directed further toward the optical member, thereby suppressing light loss from the light source 25 and enabling more uniform light to be emitted from the optical member (emblem portion) 23.

[0041] In this way, the vehicular lamp 1 according to the second embodiment can suppress a decrease in detection accuracy, as in the first embodiment. Furthermore, the vehicular lamp 1 can also have a light-emitting form with a highly aesthetic design. Furthermore, in the vehicular lamp 1, the light source 25 is located outside the radio wave emission area RA, so the presence of the light source 25 is less likely to affect the emission of radio waves. Furthermore, since the angle θ of the reflective surface Pa is 50° or less, the vehicular lamp 1 can increase the light reflection efficiency of the multiple prisms P. Furthermore, since the height h of the multiple prisms P is equal to or less than the pitch p, the vehicular lamp 1 can increase the light reflection efficiency of the multiple prisms P.

[0042] Furthermore, according to the second embodiment, the optical member 23 has a plurality of second prisms P2 on the front surface 23e, the plurality of second prisms P2 having a pitch p2 and a height h2 of 0.43 mm or less. Therefore, the vehicle lamp 1 can further improve its design by reflecting light backward by the reflective surfaces Pb of the plurality of second prisms P2, thereby illuminating the housing 22, etc.

[0043] The present disclosure has been described above based on the embodiments, but the present disclosure is not limited to the above embodiments, and modifications may be made within the scope of the spirit of the present disclosure, and techniques from the above embodiments or publicly known or well-known techniques may be combined.

[0044] For example, the shapes of various components in the above embodiments are not limited to those shown in the drawings. FIG. 5 is a cross-sectional view showing a modified example of the multiple prisms P. The multiple prisms P shown in FIGS. 3A and 3B have a bilaterally symmetrical structure. However, this is not limited to this, and the multiple prisms P may be bilaterally asymmetrical as shown in FIG. 5. This is because, particularly when the light guide direction is one direction, the angle of the reflecting surface Pa can be easily set if the multiple prisms P are asymmetrical. Furthermore, the multiple prisms P are not limited to being bilaterally asymmetrical, but may also be asymmetrical in a direction intersecting the bilaterally, such as up and down. In addition, the multiple second prisms P2 may be asymmetrical.

[0045] Furthermore, the plurality of prisms P and the plurality of second prisms P2 may have different shapes inside and outside the radio wave emission area RA.

[0046] In addition, in the above embodiment, the vehicle lamp 1 is provided in the center of the front of the vehicle, but this is not limited to this, and it may be provided in a different position, such as a position slightly spaced to the left or right of the front, or in the center of the rear.

[0047] Furthermore, in the above embodiment, the vehicle lamp 1 is provided with the mask 27, but is not limited to this, and may not be provided with the mask 27.

[0048] Furthermore, in the above embodiment, the radar device 21 has both the function of emitting and receiving radio waves, but this is not limited to this. Only the receiving part may be located outside the vehicle lamp 1, and only the radio wave emitting part of the radar device 21 may be provided in the vehicle lamp 1.

[0049] DESCRIPTION OF SYMBOLS 1: Vehicle lamp 21: Radar device (radio wave emitting means) 23: Optical member 23c: Introducing portion 23d: Rear surface (surface opposite to a predetermined direction) 23e: Front surface (surface on the side of a predetermined direction) 24: Light guide member 25: Light source 26: Lens (lens member) 27: Mask (pattern forming portion) LS: Light emitting surface P: Plural prisms P2: Plural second prisms Pa, Pb: Reflecting surfaces RA: Radio wave emitting area S1, S2: Surface on the directly facing side h, h2: Height p, p2: Pitch θ, θ2: Angle

Claims

1. A vehicle lamp comprising: a radio wave emitting means for emitting radio waves in a predetermined direction; an optical element that is arranged so as to overlap a radio wave emitting area on the side of the radio wave emitting means in the predetermined direction, and that has a plurality of prisms on at least a surface opposite the predetermined direction, the prisms having a reflective surface that introduces light from a light source from a direction intersecting the predetermined direction and reflects it toward the predetermined direction, the reflective surfaces of the plurality of prisms forming a light emitting surface; and a lens element that is arranged on the side of the optical element in the predetermined direction and introduces light from the optical element and emits it in the predetermined direction, wherein the light emitting surface of the optical element overlaps with the radio wave emitting area, and the pitch and height of the plurality of prisms at least within the radio wave emitting area are 0.43 mm or less.

2. A vehicle lamp according to claim 1, further comprising a pattern forming section for cutting a portion of the light from the plurality of prisms of the optical member to illuminate the light in a predetermined pattern.

3. The vehicle lamp according to claim 1, wherein the light source is located outside the radio wave radiation area and introduces light to the optical member via a light-guiding member.

4. The vehicle lamp according to claim 1, characterized in that the optical element has a surface facing the light guide direction of the introduced light from the light source as the reflecting surface of the plurality of prisms, and the reflecting surface has an angle of 50° or less with respect to a plane perpendicular to the predetermined direction in a cross section along the light guide direction.

5. The vehicle lamp according to claim 1, wherein the height of the plurality of prisms is equal to or less than the pitch.

6. The vehicle lamp according to claim 1, characterized in that the optical element has a plurality of second prisms on the surface on the side facing the predetermined direction, the light from the light source is reflected to the opposite side of the predetermined direction by the reflective surfaces of the plurality of second prisms, and the pitch and height of the plurality of second prisms are 0.43 mm or less at least within the radio wave emission area.

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