JP7523011B2 - Vehicle lighting fixtures - Google Patents

Description

This disclosure relates to vehicle lighting.

As disclosed in Patent Document 1, it is known to use a first and second additional reflector to cause an additional lens to emit light. As disclosed in Patent Document 2, it is known to place a translucent member provided with a light diffusion element between adjacent lamp units (see paragraph 0045 of the same document).

Patent No. 6199104 JP 2018-137144 A

When an additional lens is provided in addition to the main lens to expand the light-emitting area of a vehicle lamp, and the light emitted from the light source for the main lens is guided to the additional lens via the first and second reflectors, there is a risk that the amount of light reaching the main lens from the light source will be reduced by the first reflector. The inventors of the present application have discovered a new problem of making the additional lens emit light with a more sufficient light-emitting area or desired brightness distribution while minimizing the effect on the propagation of the light flux from the light source to the main lens.

A vehicle lamp according to one aspect of the present disclosure includes a light source, a main lens on which a first light flux included in the radiated light emitted from the light source is incident, an additional lens provided adjacent to the main lens, and first and second reflectors provided to guide a second light flux included in the radiated light to the additional lens, the second light flux being reflected by the first reflector and then reflected by the second reflector. The reflecting surface of the first reflector for the second light flux is narrower than the reflecting surface of the second reflector for the second light flux. Furthermore, a light-transmitting portion is provided between the reflecting surface of the first reflector and the reflecting surface of the second reflector. The light-transmitting portion is configured to diffuse and radiate the second light flux toward the reflecting surface of the second reflector. The first light flux and the second light flux are light fluxes propagating in different directions.

In some embodiments, the light-transmitting portion is provided on the leg of at least one of the main lens and the additional lens. In some cases, the light-transmitting portion is provided on the leg of the additional lens.

In some embodiments, the light-transmitting portion has a light entrance surface and/or a light exit surface on which a lens array of diffusing lens elements is provided.

In some embodiments, the area of the lens array is larger than the reflective surface of the first reflector.

In some embodiments, the vehicle lamp further includes a main reflector that reflects the first light flux toward the main lens. The lens array may be provided offset upward or downward from the first reflector with respect to a reference plane on which the light source is provided. The second reflector may be provided offset upward or downward from the first reflector with respect to a reference plane on which the light source is provided.
A second beam of light may propagate from the light source to the first reflector without being reflected by the main reflector.

In some embodiments, the vehicle lamp further includes a shade disposed between the main reflector and the main lens. The second light beam can propagate from the light source to the first reflector without being blocked by the shade.

In some embodiments, the first reflector is positioned so as not to impede the propagation of the first light beam.

In some embodiments, the main reflector is formed on an inner surface of the housing part, and the first and second reflectors are provided on first and second wall portions, respectively, on either side of the opening in the housing part.

According to one aspect of the present disclosure, it is possible to facilitate the additional lens to emit light with a more sufficient light-emitting area or desired luminance distribution while minimizing the effect on the propagation of light flux from the light source to the main lens.

FIG. 1 is a schematic exploded perspective view of a lamp unit according to an embodiment of the present disclosure. 1 is a front view of the lamp unit, showing the main lens and the additional lens arranged adjacent to each other (housing parts and the like are not shown). 1 is a schematic top view of a lamp unit according to an embodiment of the present disclosure. FIG. 4 is a schematic diagram of a lamp unit according to one embodiment of the present disclosure, corresponding to the dashed dotted line X3-X3 in FIG. FIG. 5 is a schematic diagram of a lamp unit according to one embodiment of the present disclosure, in which an additional lens (and a lens array of diffusing lens elements provided on the legs of the additional lens) is additionally shown compared to FIG. 4 . 1 is a schematic partial cross-sectional view of a leg of an additional lens, showing a lens array of diffusing lens elements provided on its light exit surface. 3 is a front view of the lamp unit, showing a state in which the main lens and the additional lens are disposed adjacent to each other in a manner different from that shown in FIG. 2 . 1A to 1C are schematic diagrams showing variations in optical path design. 1A to 1C are schematic diagrams showing variations in optical path design.

Non-limiting embodiments and features of the present invention will be described below with reference to the drawings. Those skilled in the art will be able to combine the various embodiments and/or features without the need for excessive explanation, and will also be able to understand the synergistic effects of such combinations. In principle, overlapping explanations between embodiments will be omitted. The reference drawings are primarily intended to describe the invention, and have been simplified for the convenience of drawing. Each feature is not only valid for the lamp unit disclosed in this specification, but is understood as a universal feature that is applicable to various other lamp units not disclosed in this specification.

In this specification, the inside of the vehicle, the outside of the vehicle, and the vehicle width direction are understood based on the vehicle on which the vehicle lamp is attached. The same applies to the front-rear direction, the left-right direction, and the up-down direction. The inside of the vehicle is the direction from any position outside the vehicle to any position inside the vehicle. The outside of the vehicle is the direction from any position inside the vehicle to any position outside the vehicle. The inside and outside of the vehicle can be included in any plane that intersects or is perpendicular to the up-down direction. The inside and outside of the vehicle can also be understood in the front-rear direction and the vehicle width direction, respectively. The up-down direction typically coincides with the vertical direction.

The vehicle lamp has a lamp unit 1 shown in FIG. 1. For example, the vehicle lamp is a headlamp of a vehicle (e.g., an automobile), in which the lamp unit 1 is housed. Typically, the lamp unit 1 is disposed within a lamp chamber defined by a lamp housing (opening toward the front of the vehicle) and an outer lens.

The lamp unit 1 is configured to form a low beam light distribution pattern (or a part thereof) and/or a high beam light distribution pattern (or a part thereof), and in the example illustrated in this application, it is configured to form a low beam light distribution pattern.

The lighting unit 1 is a projector-type lighting unit, and includes a light source 2, a main lens 3, an additional lens 4 provided adjacent to the main lens 3, a first reflector 5, a second reflector 6, a shade 7, a housing part 9 provided with a main reflector 8, a heat sink 11, a frame member 12, and a light-transmitting part 13.

The light source 2 is a light source for forming a low beam light distribution pattern and/or a high beam light distribution pattern. The light source 2 includes one or more semiconductor light emitting elements such as an LED (Light Emitting Diode) or an LD (Laser Diode) that are driven (e.g., PWM (Pulse Width Modulation) driven) by a driver (not shown) to light up. The light source 2 typically includes multiple LEDs (typically an LED array) and a substrate on which these LEDs are mounted.

A light beam is emitted from the light source 2 by driving a semiconductor light emitting element such as an LED or LD. As will be understood from the explanation below, a first light beam of the radiated light emitted from the light source 2 is incident on the main lens 3 (after being reflected by the main reflector 8), and a second light beam of the radiated light emitted from the light source 2 is incident on the first reflector 5 (for example, without being reflected by the main reflector 8). The second light beam is a direct light beam to the first reflector 5. The light source 2 has a divergence angle that causes the light beam to be directly incident on the first reflector 5.

The light source 2 is thermally connected to the heat sink 11, and heat is dissipated through the heat sink 11. An air-cooling mechanism such as an electric fan is attached to the heat sink 11, and the operation of the fan promotes the dissipation of heat from the heat sink 11 to the air.

Phosphors, lenses, wavelength conversion plates, polarizing plates, etc. may be incorporated into the light source 2. For example, a phosphor plate that is excited by light of a specific wavelength (or a specific wavelength band) emitted from an LED and emits light of a wide bandwidth (e.g., white light) is incorporated into the light source 2.

The main lens 3 is an aspheric lens that inverts an image and projects it forward. In this case, the light image formed by the shade 7 (i.e., a low beam light distribution pattern having a cutoff line) is inverted and projected forward. A first light beam contained in the light emitted from the light source 2 is incident on the main lens 3. When the main reflector 8 is provided, a light beam emitted upward from the light source 2 and reflected forward by the main reflector 8 is incident on the main lens 3.

The main lens 3 has a lens portion 31 having a light entrance surface 33 and a light exit surface 34, and a plurality of (for example, a pair of upper and lower) flange portions 32a, 32b (sometimes simply referred to as flange portions 32) for mounting the main lens 3. The main lens 3 is made of resin or glass. One or both of the light entrance surface 33 and the light exit surface 34 of the main lens 3 may be aspheric. Note that if an additional light source for a high beam light distribution pattern is provided in the lamp unit 1, or if the shade position is switched to switch between high beam and low beam, the main lens 3 also projects a high beam light distribution pattern.

The additional lens 4 is provided adjacent to the main lens 3 in the vehicle width direction (see FIG. 2). The additional lens 4 adds an additional light-emitting area to the light-emitting area of the main lens 3 in order to increase the visibility of the vehicle lamp when it is turned on. It is sufficient for the additional lens 4 to fulfill its purpose, and it is not necessary to form an additional light distribution pattern to the low beam light distribution pattern or high beam light distribution pattern formed by the main lens 3 (of course, it may be done that way). By using a part of the emitted light (i.e., the second light flux) of the light source 2 for the main lens 3 for the light emission of the additional lens 4, the visibility of the vehicle lamp when it is turned on is increased without an additional light source for the additional lens 4 (i.e., it becomes easier to see by observers around the vehicle). The additional lens 4 may be given an additional role (for example, a role as a clearance lamp).

The additional lens 4 has a lens main portion 41 and a leg portion 42 that extends from the lens main portion 41 toward the inside of the vehicle (e.g., rearward) (see Figs. 1 and 3). The lens main portion 41 functions as a light-emitting portion when the light source 2 is turned on. The lens main portion 41 is triangular when viewed from the front of the lamp (see Fig. 2), but is not limited to this shape and may be another polygon (e.g., quadrangle). The lens main portion 41 functions to refract the rays of the second light beam. The leg portion 42 is located between the reflective surface of the first reflector 5 and the reflective surface of the second reflector 6.

The lens main part 41 of the additional lens 4 may be disposed forward of the main lens 3. In this case, it is advisable to provide an inclined surface 49 on the side of the additional lens 4 facing the main lens 3 so that the first light beam emitted from the main lens 3 toward the front of the vehicle is not blocked by the additional lens 4. The inclined surface 49 is inclined obliquely (specifically, at an acute angle) along the optical axis AX of the main lens 3 so as to connect the front surface of the lens main part 41 of the additional lens 4 to the side of the leg part 42.

The leg 42 is made of the same transparent material as the main lens 41 of the additional lens 4, and is typically injection molded integrally with the main lens 41 of the additional lens 4 using the same injection molding die. The leg 42 is a flat plate provided so as to intersect (e.g., perpendicular to) the vehicle width direction, and has a light entrance surface 43 and a light exit surface 44. The light entrance surface 43 and the light exit surface 44 of the leg 42 are provided so as to intersect perpendicularly to the vehicle width direction, but can also be provided at an angle. A lens array 46 of a diffusing lens element 45 can be provided on one or both of the light entrance surface 43 and the light exit surface 44 of the leg 42 (see Figures 5 and 6).

The first and second reflectors 5 and 6 are provided to guide the second light beam contained in the light emitted from the light source 2 to the additional lens 4. The second light beam is reflected by the first reflector 5 and then reflected by the second reflector 6. The first reflector 5 is provided at a position that does not significantly or completely impede the propagation of the first light beam incident on the main lens 3 described above. In this case, the second light beam incident on the first reflector 5 is considered as unnecessary light for the main lens 3. By guiding such a second light beam to the additional lens 4 using the first reflector 5 and the second reflector 6, the light utilization efficiency of the entire lighting unit 1 is improved, and/or the second light beam becomes stray light, which causes an undesirable phenomenon such as glare, is suppressed.

The first reflector 5 is provided at a position where the light beam from the light source 2 is directly incident without passing through the main reflector 8. Additionally or alternatively, the first reflector 5 is provided at a position where the light beam from the light source 2 is directly incident without being blocked by the shade 7. The second light beam is directly incident on the first reflector 5 from the light source 2 (without being reflected by the main reflector 8 and/or being blocked by the shade 7). In order to satisfy the above points or for another purpose, the first reflector 5 is provided at a position higher than the reference plane PL on which the light source 2 is installed (see Figures 2, 4, and 5). On the other hand, the second reflector 6 is provided offset downwardly compared to the first reflector 5 with respect to the reference plane PL on which the light source 2 is installed (see Figure 2). By positioning the first reflector 5 and the second reflector 6 with a height difference in this way, the distance between the first reflector 5 and the second reflector 6 can be increased, increasing the degree of freedom in the relative orientation of the reflective surfaces of the two reflectors, and in some cases making it easier to expand the light-emitting area of the additional lens 4.

In this embodiment, the reflecting surface of the first reflector 5 (for the second light flux) is narrower than the reflecting surface of the second reflector 6 (for the second light flux). Furthermore, a light-transmitting portion 13 is provided between the reflecting surface of the first reflector 5 and the reflecting surface of the second reflector 6, and the light-transmitting portion 13 is configured to diffuse and radiate the second light flux toward the reflecting surface of the second reflector 6. This configuration promotes the additional lens 4 to emit light with a more sufficient light-emitting area or desired luminance distribution while suppressing the effect on the propagation of the light flux from the light source 2 to the main lens 3.

Specifically, it is promoted to make the first reflector 5 smaller than the second reflector 6 (at least in terms of the reflective surface). The reflective surface of the second reflector 6 can be enlarged by light diffusion by the light-transmitting portion 13 between the reflective surface of the first reflector 5 and the reflective surface of the second reflector 6, and the light-emitting area of the additional lens 4 can be enlarged as well. Since the second light flux is diffused in advance by the light-transmitting portion 13 before entering the second reflector 6, it is also easier to obtain a desired luminance distribution (e.g., a more uniform luminance distribution) in the additional lens 4. In addition, it is promoted that the influence of the second light flux is reduced and the lens main portion 41 emits light more uniformly when viewed from outside the vehicle.

The reflecting surface of the first reflector 5 may be flat, curved, or parabolic for total reflection of the light beam thereon. Each of these reflecting surfaces may be appropriately shaped for proper optical path design of the second light beam L2 between the reflecting surface of the first reflector 5 and the reflecting surface of the second reflector 6.

The light-transmitting portion 13 can be provided as an independent member separate from the main lens 3 and the additional lens 4, but it can also be provided on the legs of at least one of the main lens 3 and the additional lens 4, which increases the assembly efficiency of the lamp unit 1 and also promotes cost reduction of the lamp unit 1. If legs are provided on the main lens 3, it may become difficult to reuse it in another lamp unit. On the other hand, there is no such problem with the additional lens 4.

In the case shown in FIG. 2, the light-transmitting portion 13 is provided on the leg portion 42 of the additional lens 4, and the leg portion 42 of the additional lens 4 is endowed with a light diffusion function. The light diffusion of the second light flux by the light-transmitting portion 13 before it is reflected by the second reflector 6 promotes the lens main portion 41 of the additional lens 4 to emit light with a more uniform luminance distribution.

The leg 42 of the additional lens 4 extends along (e.g., parallel to) the optical axis AX of the main lens 3 at a position a predetermined distance away from the optical axis AX. The leg 42 is disposed close to the side surface 35 that connects the light entrance surface 33 and the light exit surface 34 of the main lens 3, and does not impede the propagation of the first light flux that enters the main lens 3 from the light source 2 via the main reflector 8. Note that the points described in this paragraph also apply to a configuration in which the leg 42 of the additional lens 4 does not have a light-transmitting portion 13 (e.g., a configuration in which the light-transmitting portion 13 is provided as an independent member separate from the additional lens 4).

The light-transmitting section 13 may have a light entrance surface and/or a light exit surface on which a lens array 46 of the diffusion lens elements 45 is provided (see Figs. 5 and 6). In the lens array 46, the diffusion lens elements 45 are arranged in various two-dimensional forms. In the illustrated example, the diffusion lens elements 45 are arranged in a matrix in the lens array 46. The diffusion lens elements 45 may be formed into a long rod shape vertically or front-to-back, and the lens array may be striped by arranging them adjacent to each other. Each diffusion lens element 45 is a convex lens, but may also be a concave lens. The diffusion lens element 45 diffuses the light beam based on the refraction of the light beam on the lens surface, and is configured to obtain an appropriate diffusion angle. The diffusion lens element 45 is substantially transparent to the light beam, like other lenses, and the light loss therein is negligible. In addition, in order to impart a light diffusion function to the light-transmitting section 13, diffusion means other than the diffusion lens elements (diffusion layers formed by various film-forming techniques, embossing, frosting, etc.) may also be provided.

The area of the lens array 46 (i.e., the total installation area of the diffusion lens elements) is larger than the reflecting surface of the first reflector 5 (see FIG. 5), which promotes the diffusion of the second light beam coming from the first reflector 5 without leakage. In other words, the reflecting surface of the first reflector 5 can be made smaller, which avoids or suppresses the first reflector 5 from interfering with the propagation of the first light beam that should be incident on the main lens 3.

The lens array 46 is offset downwards from the first reflector 5 with respect to the reference plane PL on which the light source 2 is installed (see FIG. 5). By positioning the first reflector 5 and the lens array 46 with a difference in height in this way, the distance between them can be increased. Increasing the distance increases the freedom of the relative light distribution between them, and in some cases makes it easier to expand the light-emitting area of the additional lens 4.

The first reflector 5, the second reflector 6, and the main reflector 8 can be provided as metal films formed by deposition or the like, for example, on a predetermined surface of the housing part 9. The light beam is totally reflected at each reflecting surface of the first reflector 5, the second reflector 6, and the main reflector 8. The reflecting surface of the second reflector may be a diffuse reflecting surface.

The housing part 9 has a dome portion 91, and a first wall portion 93 and a second wall portion 94 provided on the left and right of an opening (front opening in the illustrated example) 92 of the dome portion 91. The dome portion 91 is provided so as to define a parabolic reflective surface as its inner surface, and opens forward and downward. Above and below the opening 92 of the dome portion 91 are provided flange portions 95a and 95b to which the flange portions 32a and 32b of the main lens 3 are attached.

A main reflector 8 is provided on the inner surface of the dome portion 91 of the housing part 9, or is formed there as a metal film. A first reflector 5 is provided on the first wall portion 93 of the housing part 9, or is formed there as a metal film. A second reflector 6 is provided on the second wall portion 94 of the housing part 9, or is formed there as a metal film. The main reflector 8 can be provided integrally with the housing part 9, i.e. inseparably. The second wall portion 94 can be provided as a separate body rather than as part of the housing part 9. The second wall portion 94 can also be oriented so that the angle that the second wall portion 94 makes with respect to the optical axis AX of the main lens 3 is 100° or more in order to increase the light-emitting area of the additional lens 4.

The shade 7 is provided between the main reflector 8 and the main lens 3, and blocks the propagation of a portion of the first light beam reflected by the main reflector 8. The remaining portion of the first light beam reflected by the main reflector 8 reaches the main lens 3 through the space above the shade 7. The shade 7 is made of any material capable of blocking the propagation of visible light, such as a steel plate. In some embodiments, the shade 7 is omitted, or an additional or alternative shade is provided.

The assembly of the lamp unit 1 can be understood from FIG. 1, and a detailed description will be omitted. The housing part 9 and the shade 7 are fixed to the heat sink 11 or a board mounted thereon by screws or the like, but this is not necessarily the case.

The operation of the lamp unit 1 will be described. When the light source 2 is turned on, it emits radiant light. The first light beam L1 contained in the radiant light of the light source 2 travels upward and is totally reflected by the reflecting surface of the main reflector 8, and then propagates along the optical axis AX of the main lens 3 toward the outside of the vehicle and reaches the main lens 3 (see FIG. 4). A shade 7 is provided between the main reflector 8 and the main lens 3, which prevents a portion of the first light beam L1 from propagating toward the main lens 3. As a result, the light image that reaches the main lens 3 beyond the shade 7 has a cutoff line for a low beam light distribution pattern. This light image is inverted by the main lens 3 and projected forward of the vehicle.

The second light beam L2 contained in the emitted light of the light source 2 propagates diagonally to the upper right toward the first reflector 5, is totally reflected by the reflecting surface of the first reflector 5, intersects with the optical axis AX of the main lens 3, propagates in the vehicle width direction (left side), and enters the leg 42 (translucent portion 13) (see Figures 3 and 4). The second light beam L2 is optically controlled by each diffusion lens element 45 of the light exit surface 44 of the leg 42 (translucent portion 13) so as to be diffused and emitted from the leg 42 (translucent portion 13). Next, the second light beam L2 propagates while diffusing toward the reflecting surface of the second reflector 6, and is totally reflected by the reflecting surface of the second reflector 6. Next, the second light beam L2 propagates toward the outside of the vehicle along the optical axis AX of the main lens 3 and reaches the lens main portion 41 of the additional lens 4. A diffuse light beam enters the additional lens 4, and this light beam passes through the additional lens 4 and is projected forward of the vehicle. The additional lens 4 adds an additional light-emitting area to the light-emitting area of the main lens 3, expanding the light-emitting area of the vehicle lamp and improving the visibility of the vehicle lamp when it is turned on. In addition to the diffusion lens element of the translucent portion 13, an additional diffusion lens element can also be provided on the additional lens 4.

As shown in FIG. 7, the arrangement of the first reflector 5 and the second reflector 6 may be reversed in the vehicle width direction. In this case, the second light beam propagates diagonally from the light source 2 toward the first reflector 5 toward the upper left, is reflected by the first reflector 5, and propagates to the right. As described above, the leg 42 (i.e., the light-transmitting portion 13) of the additional lens 4 is provided between the reflecting surface of the first reflector 5 and the reflecting surface of the second reflector 6.

In the case of FIG. 8, the reflecting surface of the second reflector 6 is set to a curved surface or a parabolic surface, and a different optical path is set from that described above. In such a case, the same effect can be achieved within the scope of the above disclosure. The second light flux incident on the front region of the light-transmitting section 13 is emitted forward from the adjacent region of the additional lens 4 that is closer to the optical axis AX of the main lens 3, and the second light flux incident on the rear region of the light-transmitting section 13 is emitted forward from the distant region of the additional lens 4 that is farther away from the optical axis AX of the main lens 3.

In the case of FIG. 9, the reflecting surface of the first reflector 5 is set to a curved surface or a parabolic surface, and a different optical path is set from that described above. In such a case, the same effect can be achieved within the scope of the above disclosure. The second light beam L2 propagates so as to converge toward a predetermined position behind the main lens 3 and then diverge.

Various design modifications are possible for the various forms or features described above, and these are also within the scope of the present disclosure. Figures 7 to 9 are understood as variations of the present disclosure, but other further design modifications will be obvious to those skilled in the art. The diffusing lens element may be a concave lens and provided on the light entrance surface of the light-transmitting portion.

1: Lighting unit 2: Light source 3: Main lens 4: Additional lens 5: First reflector 6: Second reflector 7: Shade 8: Main reflector 9: Housing parts

13: Light transmitting part

42: Leg 45: Diffusion lens element

Claims (11)

A vehicular lamp comprising: a light source; a main lens on which a first light flux included in radiation light emitted from the light source is incident; an additional lens provided adjacent to the main lens; and first and second reflectors provided to guide a second light flux included in the radiation light to the additional lens, the second light flux being reflected by the first reflector and then reflected by the second reflector,
a reflecting surface of the first reflector for the second light beam is narrower than a reflecting surface of the second reflector for the second light beam,
a light-transmitting portion is provided between the reflective surface of the first reflector and the reflective surface of the second reflector, the light-transmitting portion being configured to diffuse and radiate the second light flux toward the reflective surface of the second reflector. The vehicle lamp according to claim 1, characterized in that the light-transmitting portion is provided on the leg of at least one of the main lens and the additional lens. The vehicle lamp according to claim 2, characterized in that the light-transmitting portion is provided on the leg of the additional lens. The vehicle lamp according to claim 2 or 3, characterized in that the light-transmitting portion has a light entrance surface and/or a light exit surface on which a lens array of diffusing lens elements is provided. The vehicle lamp according to claim 4, characterized in that the area of the lens array is larger than the reflecting surface of the first reflector. a main reflector that reflects the first light flux toward the main lens;
6. The vehicle lamp according to claim 4, wherein the lens array is offset upward or downward as compared with the first reflector with respect to a reference plane on which the light source is disposed. The vehicle lamp according to claim 6, characterized in that the second reflector is offset upward or downward from the first reflector with respect to a reference plane on which the light source is installed. The vehicle lamp according to any one of claims 1 to 7, further comprising a main reflector that reflects the first light beam toward the main lens, and the second light beam propagates from the light source to the first reflector without being reflected by the main reflector. The vehicle lamp according to claim 8, further comprising a shade provided between the main reflector and the main lens, wherein the second light beam propagates from the light source to the first reflector without being blocked by the shade. The vehicle lamp according to any one of claims 1 to 9, characterized in that the first reflector is provided at a position that does not impede the propagation of the first light beam. The vehicle lamp according to any one of claims 1 to 10, further comprising a main reflector that reflects the first light beam toward the main lens, the main reflector being formed on the inner surface of the housing part, and the first and second reflectors being provided on first and second wall portions on both sides of the opening of the housing part, respectively.