Vehicle lamp

Abstract

A vehicle lamp includes a light source, and a reflector including a diffusion/reflection surface configured to diffuse and reflect light emitted from the light source toward a front surface side, the diffusion/reflection surface has a curved surface shape that forms a curve according to directionality of the light emitted from the light source in a cross section in at least one direction along an optical axis of the light emitted from the light source.

Claims

1. A vehicle lamp comprising: a light source; and a reflector including a diffusion/reflection surface configured to diffuse and reflect light emitted from the light source toward a front surface side, wherein directionality of light emitted from the light source is a Lambertian light distribution, wherein the diffusion/reflection surface has a concave curved surface shape that forms a cosine curve according to a directionality of light emitted from the light source in a cross section in at least one direction along an optical axis of the light emitted from the light source, wherein the cosine curve is a curve expressed by an equation B=Acos in a case provided that: a distance A is a distance from the light source to the diffusion/reflection surface when an emission angle of the light is 0; and a distance B is a distance from the light source to the diffusion/reflection surface when the emission angle of the light is .

2. The vehicle lamp according to claim 1, wherein the diffusion/reflection surface has a curved surface shape that forms an arc about an optical axis of the light emitted from the light source or a curved surface shape that forms a curve approximate to the arc in a cross section in other direction which is perpendicular to the optical axis and which is perpendicular to the one direction.

3. The vehicle lamp according to claim 2, wherein the diffusion/reflection surface includes a fine concavo-convex structure.

4. The vehicle lamp according to claim 2, wherein a plurality of light sources are arranged side by side, the reflector includes a plurality of diffusion/reflection surfaces corresponding to the light sources, respectively, and the diffusion/reflection surfaces are provided continuously in a direction in which light sources are arranged.

5. The vehicle lamp according to claim 2, wherein the vehicle lamp is a tail lamp of a vehicle.

6. The vehicle lamp according to claim 1, wherein the reflector is constituted by a reflection member having a light diffusion ability.

7. The vehicle lamp according to claim 6, wherein the diffusion/reflection surface includes a fine concavo-convex structure.

8. The vehicle lamp according to claim 6, wherein a plurality of light sources are arranged side by side, the reflector includes a plurality of diffusion/reflection surfaces corresponding to the light sources, respectively, and the diffusion/reflection surfaces are provided continuously in a direction in which light sources are arranged.

9. The vehicle lamp according to claim 6, wherein the vehicle lamp is a tail lamp of a vehicle.

10. The vehicle lamp according to claim 1, wherein the diffusion/reflection surface includes a fine concavo-convex structure.

11. The vehicle lamp according to claim 10, wherein a plurality of light sources are arranged side by side, the reflector includes a plurality of diffusion/reflection surfaces corresponding to the light sources, respectively, and the diffusion/reflection surfaces are provided continuously in a direction in which light sources are arranged.

12. The vehicle lamp according to claim 10, wherein the vehicle lamp is a tail lamp of a vehicle.

13. The vehicle lamp according to claim 1, wherein a plurality of light sources are arranged side by side, the reflector includes a plurality of diffusion/reflection surfaces corresponding to the light sources, respectively, and the diffusion/reflection surfaces are provided continuously in a direction in which light sources are arranged.

14. The vehicle lamp according to claim 1, wherein the vehicle lamp is a tail lamp of a vehicle.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a cross-sectional view of a vehicle lamp according to a first embodiment of the present invention in a vertical direction.

(2) FIG. 2A is a perspective view showing a configuration of a reflector provided in the vehicle lamp shown in FIG. 1.

(3) FIG. 2B is a plan view when the perspective view of the configuration of the reflector shown in FIG. 2A is seen from above.

(4) FIG. 3 is a graph showing directionality of light emitted from a light source on polar coordinates and orthogonal coordinates.

(5) FIG. 4 is a cross-sectional view for describing a shape of a diffusion/reflection surface of the reflector.

(6) FIG. 5 is a cross-sectional view showing a configuration to which a subsidiary reflector is added.

(7) FIG. 6 is a cross-sectional view showing a configuration in which an optical axis of light emitted from the light source is inclined with respect to a vertical direction.

(8) FIG. 7A is a graph showing another directionality of light emitted from the light source on polar coordinates.

(9) FIG. 7B is a cross-sectional view showing a shape of the diffusion/reflection surface of the reflector according to the directionality of the light shown in FIG. 7A.

(10) FIG. 8 is a plan view seeing from above a configuration in which a plurality of light sources and a plurality of reflectors are disposed next to each other.

(11) FIG. 9 is a perspective view showing a configuration of the reflector on which a plurality of diffusion/reflection surfaces are provided continuously.

(12) FIG. 10 is a plan view showing a configuration of a vehicle lamp according to a second embodiment of the present invention.

(13) FIG. 11 is a cross-sectional view of the vehicle lamp along a line segment X-X shown in FIG. 10.

(14) FIG. 12 is a photograph showing a light source image when a viewing angle with respect to the vehicle lamp shown in FIG. 10 is 15 outward in the vehicle width direction.

(15) FIG. 13 is a photograph showing a light source image when a viewing angle with respect to the vehicle lamp shown in FIG. 10 is 30 outward in the vehicle width direction.

(16) FIG. 14 is a photograph showing a light source image when a viewing angle with respect to the vehicle lamp shown in FIG. 10 is 45 outward in the vehicle width direction.

(17) FIG. 15 is a photograph showing a light source image when a viewing angle with respect to the vehicle lamp shown in FIG. 10 is 10 upward from the vehicle.

DESCRIPTION OF EMBODIMENTS

(18) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(19) Further, in the drawings used in the following description, in order to make each component easier to see, dimensions may be shown at different scales depending on the component, and dimensional ratios in respective components may not be the same as in reality.

First Embodiment

(20) First, as a first embodiment of the present invention, for example, a vehicle lamp 1 shown in FIG. 1 to FIG. 4 will be described.

(21) Further, FIG. 1 is a cross-sectional view of the vehicle lamp 1 in a vertical direction. FIG. 2A is a perspective view of a configuration of a reflector 3 provided in the vehicle lamp 1, and FIG. 2B is a plan view when the perspective view of the configuration of the reflector shown in FIG. 2A is seen from above. FIG. 3 is a graph showing directionality of light emitted from a light source 2 on polar coordinates and orthogonal coordinates. FIG. 4 is a cross-sectional view for describing a shape of a diffusion/reflection surface 3a of the reflector 3.

(22) In addition, in the drawings described below, an XYZ orthogonal coordinates system is set, an X-axis direction indicates a forward/rearward direction (a lengthwise direction) of the vehicle lamp 1, a Y-axis direction indicates a leftward/rightward direction (a widthwise direction) of the vehicle lamp 1, and a Z-axis direction indicates an upward/downward direction (a height direction) of the vehicle lamp 1.

(23) As shown in FIG. 1 and FIG. 2, the vehicle lamp 1 of the embodiment is obtained by applying the present invention to tail lamps configured to emit red light, in rear combination lamps mounted on both corner portions of a rear end side of a vehicle (not shown) (in the embodiment, a corner portion on a left rear end side).

(24) Further, in the following description, terms of forward, rearward, leftward, rightward, upward and downward refer to the respective directions when, the vehicle lamp 1 is viewed from the front (a side behind the vehicle) unless the context indicates otherwise. Accordingly, when looking at the vehicle from the front (a side in front of the vehicle), each direction is the opposite of the above-mentioned forward, rearward, leftward and rightward.

(25) As shown in FIG. 1, FIG. 2A and FIG. 2B, the vehicle lamp 1 of the embodiment includes the light source 2 and the reflector 3, and is disposed inside a lighting body (not shown) that constitutes a rear combination lamp.

(26) Further, the lighting body is constituted by a housing with a front surface opening, and an outer lens (a cover lens) configured to cover the opening of the housing. In addition, a shape of the lighting body can be appropriately changed according to a design or the like of the vehicle.

(27) The light source 2 is constituted by a light emitting diode (LED) configured to emit red light (hereinafter, referred to as light) L. The light source 2 is mounted on a side of one surface (in the embodiment, a lower surface) of a circuit board 4 on which a driving circuit configured to drive the LED is provided. Accordingly, the light source 2 radially emits the light L in a direction perpendicular to the one surface of the circuit board 4 (in the embodiment, downward).

(28) The reflector 3 is disposed below the light source 2, and has the diffusion/reflection surface 3a configured to diffuse and reflect the light L emitted from the light source 2 toward a front surface side. For example, a reflection member having a light diffusion property such as a white glass epoxy resin or the like is used for the reflector 3. In addition, particles such as titanium oxide or the like contained in a white reflection member has a function of diffusing light. In addition, for example, the diffusion/reflection surface 3a is composed of a reflecting surface including a fine concavo-convex structure for randomly diffusing the light L such as embossing or the like.

(29) Incidentally, in the vehicle lamp 1 of the embodiment, the diffusion/reflection surface 3a of the reflector 3 has a curved surface shape that forms a curve according to directionality of the light L emitted from the light source 2 in a cross section (hereinafter, referred to as a vertical cross section) in at least one direction (in the embodiment, a vertical direction of the reflector 3) along an optical axis AX of the light L emitted from the light source 2.

(30) Specifically, the diffusion/reflection surface 3a has a curved surface shape that forms a curve in which a distance from the light source 2 increases as a light intensity according to an emission angle of the light L emitted from the light source 2 increases in a vertical cross section.

(31) Here, the directionality of the light L emitted from the light source 2 is a Lambertian light distribution as shown in FIG. 3. The Lambertian light distribution is a light distribution in which an emission angle of the light L with respect to the optical axis AX can be expressed by a multiple of cos of the light intensity on the optical axis AX (=0). Accordingly, an emission angle (half-value angle) that is a half value of the light intensity of the optical axis AX is =60 from cos =0.5.

(32) As shown in FIG. 4, in the vertical cross section, the diffusion/reflection surface 3a is constituted by a concave curved surface that forms a cosine curve according to the Lambertian light distribution throughout an angle range in which the emission angle is at least 0 to 60 (in the embodiment, 0 to 80) and that is located on a back surface side with respect to the optical axis AX of the light L emitted from the light source 2.

(33) That is, the cosine curve is a curve expressed by the following equation (1) in a case provided that a distance A is a distance from the light source 2 to the diffusion/reflection surface 3a when the emission angle is 0 and a distance B is a distance from the light source 2 to the diffusion/reflection surface 3a when the emission angle is .

(34) $\begin{array}{cc}B=A\cos & \left(1\right)\end{array}$

(35) Further, the light intensity of the light L at the position where the emission angle is 0 (a lower end of the diffusion/reflection surface 3a) is the highest, and the distance A from the light source 2 to the diffusion/reflection surface 3a at this position is the longest. Meanwhile, the light intensity of the light L at the position where the emission angle is the largest (an upper end of the diffusion/reflection surface 3a) is the weakest, and the distance B (shown by C in FIG. 4) from the light source 2 to the diffusion/reflection surface 3a at this position is the shortest.

(36) In addition, as shown in FIG. 2A and FIG. 2B, the diffusion/reflection surface 3a has a curved surface shape that forms an arc about the optical axis AX in a cross section (hereinafter, referred to as a horizontal cross section) in the other direction (in the embodiment, a horizontal direction of the reflector 3) perpendicular to the optical axis AX of the light L emitted from the light source 2 and perpendicular to the one direction.

(37) That is, the diffusion/reflection surface 3a is constituted by a concave curved surface obtained by rotating the above-mentioned cosine curve about the optical axis AX. In addition, an angle of the horizontal cross section of the diffusion/reflection surface 3a about the optical axis AX is set to a range of, for example, 45 to 45. Further, the angle can be appropriately changed according to the distance from the light source 2.

(38) The reflector 3 has the diffusion/reflection surface 3a, a front surface side of which is open, reflects the light L that has entered the diffusion/reflection surface 3a while diffusing the light L, and emits the diffused light L toward the front surface side of the vehicle lamp 1. Accordingly, in the vehicle lamp 1 of the embodiment, it is possible to emit red light using the front surface side of the reflector 3 as a light emitting surface of a tail lamp.

(39) In the vehicle lamp 1 of the embodiment having the above-mentioned configuration, as the diffusion/reflection surface 3a of the above-mentioned reflector 3 has a curved surface shape according to directionality of the light L emitted from the light source 2, luminance of the light L diffused and reflected by the diffusion/reflection surface 3a can be made uniform throughout the entire region of the diffusion/reflection surface 3a.

(40) In addition, in the vehicle lamp 1 of the embodiment, by making the luminance of the light L diffused and reflected by the above mentioned diffusion/reflection surface 3a uniform, even when the viewing angle from the front view is increased, it is possible to make the light emitting surface of the tail lamp visible with the same brightness.

(41) Further, in the vehicle lamp 1 of the embodiment, since there is no need to add a diffusion lens like in the related art, it is possible to reduce costs while minimizing increase in the number of parts.

(42) Further, the present invention is not particularly limited to the configuration of the first embodiment, and various modifications may be made without departing from the scope of the present invention.

(43) Specifically, in the vehicle lamp 1, for example, a subsidiary reflector 5 as shown in FIG. 5 may be added. Further, FIG. 5 is a cross-sectional view showing a configuration in which the subsidiary reflector 5 is added to the vehicle lamp 1.

(44) The subsidiary reflector 5 is disposed below the light source 2 and on the front surface side of the reflector 3, and has a reflecting surface 5a configured to reflect some of the light L emitted from the light source 2 toward the diffusion/reflection surface 3a. For example, a reflection member on which a reflecting film such as an aluminum deposition film or the like is used for the subsidiary reflector 5.

(45) The reflecting surface 5a of the subsidiary reflector 5 is constituted by a concave free-form surface which is located on the front surface side with respect to the optical axis AX of the light L emitted from the light source 2 and which is located above the reflector 3 in the vertical cross section. In addition, the reflecting surface 5a has a curved surface shape that forms an arc about the optical axis AX in the horizontal cross section.

(46) In the subsidiary reflector 5, a surface side of the reflecting surface 5a facing the reflector 3 is opened, and the subsidiary reflector 5 reflects the light L that has entered the reflecting surface 5a toward a range in which the emission angle of the diffusion/reflection surface 3a is increased.

(47) Accordingly, in the vehicle lamp 1 of the embodiment, while complementing the luminance of the light L diffused and reflected within the range where the emission angle of the diffusion/reflection surface 3a is increased, the luminance of the light L diffused and reflected by the diffusion/reflection surface 3a can be made uniform over the entire area of the diffusion/reflection surface 3a.

(48) In addition, in the above-mentioned vehicle lamp 1, for example, as shown in FIG. 6, the optical axis AX of the light L emitted from the light source 2 may be inclined with respect to the vertical direction. Further, FIG. 6 is a cross-sectional view showing a configuration in which the optical axis AX of the light L emitted from the light source 2 is inclined with respect to the vertical direction.

(49) Specifically, in the configuration shown in FIG. 6, the optical axis AX of the light L emitted from the light source 2 is inclined toward the back surface side rather than the vertical direction. Correspondingly, the diffusion/reflection surface 3a includes an extension portion 5b that forms a cosine curve according to the Lambertian light distribution toward the front surface side with respect to the optical axis AX of the light L emitted from the light source 2 in the vertical cross section. In addition, the extension portion 5b is extended such that the light L diffused and reflected toward the front surface side of the diffusion/reflection surface 3a is not interfered by the extension portion 5b.

(50) Accordingly, in the vehicle lamp 1 of the embodiment, some of the light L advancing toward the front surface side with respect to the optical axis AX can be diffused and reflected by an extension portion 3b of the diffusion/reflection surface 3a, and the strong light L near the optical axis AX of the light L emitted from the light source 2 can be efficiently used.

(51) In addition, in the vehicle lamp 1, for example, it is possible to make a curved surface shape of the diffusion/reflection surface 3a as shown in FIG. 7B according to the directionality of the light L emitted from the light source 2 shown in FIG. 7A. Further, FIG. 7A is a graph showing another directionality of the light L emitted from the light source 2 on polar coordinates. FIG. 7B is a cross-sectional view showing a shape of the diffusion/reflection surface 3a of the reflector 3 according to the directionality of the light shown in FIG. 7A.

(52) That is, the diffusion/reflection surface 3a may have a curved surface shape that forms a curve according to the directionality of the light L emitted from the light source 2 in the vertical cross section, or a curved surface shape that approximates the curve.

(53) Similarly, the diffusion/reflection surface 3a is not limited to a curved surface shape that forms an arc about the optical axis AX in the horizontal cross section, but may also be a curved surface shape that forms a curve that approximates the arc.

(54) In addition, as shown in FIG. 8, the vehicle lamp, to which the present invention is applied, may include, for example, a plurality of (in the example, two) light sources 2, and a plurality of (in the example, two) reflectors 3 disposed so as to correspond to the plurality of light sources 2, respectively. Further, FIG. 8 is a plan view seen from above a configuration in which the plurality of light sources 2 and the plurality of reflectors 3 are disposed next to each other.

(55) However, in the case of the configuration, since the curved surface shape of the diffusion/reflection surface 3a is changed significantly at a boundary portion R between the neighboring diffusion/reflection surfaces 3a, the boundary portion R tends to cause dark areas of light emission.

(56) On the other hand, for example, it may also be configured to include the reflector 30 in which the plurality of (in the example, three) diffusion/reflection surfaces 3a are continuously provided as shown in FIG. 9. Further, FIG. 9 is a perspective view showing a configuration of the reflector 30 in which the plurality of diffusion/reflection surfaces 3a are continuously provided.

(57) In the case of the configuration, by increasing a curvature of the arc of the neighboring diffusion/reflection surfaces 3a in the horizontal cross section of the reflector 30, it is possible to reduce the shape change in the boundary portion R and suppress occurrence of dark areas in the boundary portion R.

(58) Further, when the curvature of the arc of the neighboring diffusion/reflection surfaces 3a is increased, while the curved surface shape at the vertical cross section of each of the diffusion/reflection surfaces 3a toward the boundary portion R deviates from an ideal shape of a cosine curve, it is possible to achieve sufficient uniformity of light emission between the neighboring diffusion/reflection surfaces 3a.

Second Embodiment

(59) Next, as a second embodiment of the present invention, for example, a vehicle lamp 10 shown in FIG. 10 and FIG. 11 will be described.

(60) Further, FIG. 10 is a plan view showing a configuration of the vehicle lamp 10. FIG. 11 is a cross-sectional view of the vehicle lamp 10 along a line segment X-X shown in FIG. 10. In addition, in the following description, the same areas as in the vehicle lamp 1 are designated by the same reference signs in the drawings, and description thereof will be omitted.

(61) As shown in FIG. 10 and FIG. 11, the vehicle lamp 10 of the embodiment includes a plurality of (in the embodiment, 13) light sources 2, and a reflector 40, and is disposed inside a lighting body (not shown) that constitutes a rear combination lamp.

(62) The reflector 40 is disposed below the plurality of light sources 2, and has a diffusion/reflection surface 40a configured to diffusing and reflecting the light L emitted from each of the light sources 2 toward the front surface side. For example, a reflection member having a light diffusion property such as a white glass epoxy resin or the like is used for the reflector 40. In addition, the diffusion/reflection surface 40a is constituted by a reflecting surface including a fine concavo-convex structure configured to randomly diffuse the light L, for example, embossing or the like.

(63) In the vehicle lamp 10 of the embodiment, the diffusion/reflection surface 40a of the reflector 40 has a curved surface shape that forms a curve according to the directionality of the light L emitted from the light source 2 in a cross section of at least one direction along the optical axis AX of the light L emitted from each of the light sources 2 (in the embodiment, a vertical cross section along a vertical line from the light source 2 to the diffusion/reflection surface 40a).

(64) Specifically, the diffusion/reflection surface 40a is constituted by a concave curve surface that forms each cosine curve in the vertical cross section corresponding to each of the light sources 2.

(65) Meanwhile, the diffusion/reflection surface 40a has a surface shape curved in an arc shape in a widthwise direction of the vehicle (hereinafter, referred to as a vehicle width direction) according to a slant shape applied to a corner portion of the rear end side of the vehicle in the horizontal cross section.

(66) For this reason, although the diffusion/reflection surface 40a has an ideal shape of a cosine curve in the vertical cross section corresponding to each of the light sources 2 described above, it deviates from the ideal shape of the cosine curve between the light sources 2.

(67) Meanwhile, since the diffusion/reflection surface 40a is continuous in the direction in which the light sources 2 are arranged, the boundary portion R between the neighboring diffusion/reflection surfaces 3a described above is not generated, and it is possible to sufficiently allow uniformity of light emission between the light sources 2.

(68) Meanwhile, both ends of the diffusion/reflection surface 40a are constituted by concave curved surfaces obtained by rotating the cosine curve about the optical axis AX of the light sources 2 disposed at both ends. Accordingly, it is possible to provide ideal cosine curve shapes at both ends of the diffusion/reflection surface 40a.

(69) In the reflector 40, the front surface side of the diffusion/reflection surface 40a is opened, the light L that has entered the diffusion/reflection surface 40a is diffused and reflected, and the light L diffused toward the front surface side of the vehicle lamp 10 is emitted. Accordingly, in the vehicle lamp 10 of the embodiment, it is possible to emit red light using the front surface side of the reflector 40 as the light emitting surface of the tail lamp.

(70) In the vehicle lamp 10 of the embodiment of the above-mentioned configuration, since the diffusion/reflection surface 40a of the reflector 40 has a curved surface shape according to the directionality of the light L emitted from each of the light sources 2, it is possible to make the luminance of the light L diffused and reflected by the diffusion/reflection surface 40a uniform over the entire area of the diffusion/reflection surface 40a.

(71) In addition, in the vehicle lamp 10 of the embodiment, by equalizing the luminance of the light L diffused and reflected by the diffusion/reflection surface 40a described above, even if the viewing angle in a front view is increased, it is possible to make the light emitting surface of the tail lamp visible with the same brightness.

(72) Further, in the vehicle lamp 10 of the embodiment, since there is no need to add the diffusion lens like in the related art, it is possible to reduce costs while minimizing the increase in the number of parts.

(73) Here, a light source image of the vehicle lamp 10 was obtained by simulation when the viewing angle with respect to the vehicle lamp 10 was 15, 30, and 45 outward in the vehicle width direction, and 10 above the vehicle. The light source images from the simulation results are shown in FIG. 12 to FIG. 15.

(74) Further, FIG. 12 is a photograph showing a light source image when a viewing angle with respect to the vehicle lamp 10 is 15 outward in the vehicle width direction. FIG. 13 is a photograph showing a light source image when a viewing angle with respect to the vehicle lamp 10 is 30 outward in the vehicle width direction. FIG. 14 is a photograph showing a light source image when a viewing angle with respect to the vehicle lamp 10 is 45 outward in the vehicle width direction. FIG. 15 is a photograph showing a light source image when a viewing angle with respect to the vehicle lamp 10 is 10 upward from the vehicle.

(75) As shown in FIG. 12 to FIG. 15, even when the viewing angle with respect to the vehicle lamp 10 is changed, it is possible to obtain a more uniform light source image with the same brightness.

(76) Further, the present invention is not necessarily limited to the configuration of the embodiment described above, and various changes may be made without departing from the scope of the present invention.

(77) In the embodiment, while the case in which the present invention is applied to the tail lamp that constitutes the above-mentioned rear combination lamp has been exemplified, the vehicle lamp to which the present invention is applied is not limited to the above-mentioned rear-side vehicle lamp, and the present invention may also be applied to a front-side vehicle lamp.

(78) That is, the vehicle lamp to which the present invention is applied is not limited to the above-mentioned tail lamp, but the present invention may be widely applied to a vehicle lamp including a light source and a reflector, for example, a stop lamp (brake lamp), a direction indicator (turn lamp), a back lamp, a lid lamp, a headlight for a vehicle (head lamp), a width indicator (position lamp), a subsidiary headlight (subsidiary head lamp), a front (rear) fog light (fog lamp), a daytime running lamp, or the like.

(79) In addition, the color of the light emitted from the light source is not limited to the above-mentioned red light, but can be changed as appropriate, such as white light or orange light, depending on the use of the vehicle lamp.

(80) Further, although the present invention is suitably used for the above-mentioned vehicle lamp, it is not necessarily limited to application to the vehicle lamp, and can also be applied to general lighting devices, such as residential lighting devices.

REFERENCE SIGNS LIST

(81) 1 . . . vehicle lamp 2 . . . light source 3 . . . reflector 3a . . . diffusion/reflection surface 4 . . . circuit board 5 . . . subsidiary reflector 5a . . . reflecting surface 10 . . . vehicle lamp 30 . . . reflector 40 . . . reflector 40a . . . diffusion/reflection surface L . . . light AX . . . optical axis