JPH04253102A - Reflecting mirror of lighting fixture for vehicle - Google Patents

Abstract

PURPOSE:To prevent the generation of a local high-temperature section on a lens located in front of a reflecting mirror. CONSTITUTION:The diffusion property for the light from a light source 11 is applied to a region 5 around an electric lamp fitting hole 4 on the reflecting surface 2 of a reflecting mirror 1. The region 5 is formed with multiple reflecting elements 5a with a hyperbolic paraboloid shape or an elliptic paraboloid shape, for example. The generation of a high-temperature section on a lens 13 due to the concentration of heat is prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel reflector for a vehicle lamp. Specifically, the present invention aims to provide a novel reflector for a vehicle lamp in which a highly diffusive reflective surface is formed in a part of the reflective surface so as to prevent localized high temperature areas from forming on the lens. It is useful when used in a lamp that has a lens made of a material that does not have high heat resistance, such as synthetic resin.

0002

[Prior Art] In vehicular lamps, such as automobile headlamps, it is common to use glass material as the material for the lens that covers the front surface of the lamp body. Due to demand, lenses made of synthetic resin have come into use.

0003

[Problems to be Solved by the Invention] By the way, the basic structure of a headlamp is as shown in FIG. The light emitted from the filament c of the light bulb (located in front of the focal point of the reflective surface a and provided for irradiating the passing beam) and then reflected at the periphery d of the light bulb mounting hole is , light rays f, f, . . . are concentrated at the central portion g of the lens b (the portion surrounded by a square indicated by a dashed dotted line), and the temperature of that portion increases.

[0004] Such concentration of heat depends on the focal length, the diameter of the light bulb mounting hole of the reflector, the distance from the focal point to the lens, etc., but if the lens b is made of synthetic resin, it may occur locally. Damage caused by thermal deformation becomes a particular problem when high-temperature areas occur.

[0005]

[Means for Solving the Problems] Therefore, in order to solve the above-mentioned problems, the present invention provides a reflective surface with a reflective area that diffuses the light emitted from the light source that reaches the periphery of the light bulb mounting hole. It was formed.

[0006]

[Function] According to the present invention, the reflection area that causes high temperature areas due to concentration of light flux on the lens, especially the area around the light bulb mounting hole, is made to have diffusive properties, so that the local parts of the lens can be diffused. temperature rise can be suppressed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Details of the reflecting mirror of the vehicle lamp of the present invention will be explained below according to the illustrated embodiments.

In FIG. 1, reference numeral 1 denotes a reflecting mirror, and most of the area 3 of its reflecting surface 2 is formed in the shape of a paraboloid of revolution. The peripheral area 5 is a multiple reflection surface consisting of a plurality of segments 5a, 5a, . . . .

In FIG. 1, the axis passing through the center of the light bulb mounting hole 4 and perpendicular to the plane of the paper is defined as the x axis, and regarding the y and z axes orthogonal to this at the origin O, the y axis is defined as an axis extending in the left-right direction, If the z-axis is chosen as the axis extending in the vertical direction, most of region 5 is in the first quadrant (y>0
, z>0) and the second quadrant (y<0, z>0), and occupies a small portion of the fourth quadrant (y>0, z<0).

[0010]The individual reflective segments 5a, 5a, . . . constituting the region 5 have the function of greatly diffusing light from a light source arranged on the X-axis in the y-axis (left and right) direction. . An example thereof is a hyperbolic paraboloid 6 as shown in FIG. 2, for example.

That is, if the X-axis is chosen to be the normal direction of the segment, the Y-axis is chosen to be an axis extending in the horizontal direction, and the axis parallel to the Z-axis is chosen to be the z-axis, this curved surface will be formed as follows with a and b as constants: Expression 1]

0012

[Math 1]

That is, the hyperbolic paraboloid 6 shown in the above formula has a cross-sectional shape (that is, a line of intersection with a plane parallel to the X-Y plane) of
It has a parabolic shape convex in the positive direction of
The line of intersection with a plane parallel to the X-Z plane forms a concave parabola in the positive direction of the X-axis.

The region 5 is formed as a set of segments 5a, 5a, . This is done as shown in .

The parabola indicated by 7 in the figure is a horizontal line of a virtual paraboloid obtained on the assumption that the region 5 does not exist in the reflecting surface 2 and the reflecting surface has a single paraboloid of revolution shape. It represents the cross-sectional shape, and the vector n represents a direction vector parallel to the optical axis at an arbitrary point P on the virtual parabola 7.

[0016] 8, 8, . . . are parabolas representing hyperbolic paraboloids (in other words, Z=0 in equation [1]), and their normal (X-axis) direction is Under the condition that it matches the direction of the vector n above and that continuity between adjacent curved surfaces is maintained, the starting and ending positions of the curved surface are determined for each segment using a and b in formula [1] as parameters. By giving each segment 5a, 5a, .
...is designed.

Note that the segments 5a, 5a, . . .
The shape of * is not limited to a hyperbolic paraboloid as long as it has a large diffusion effect in the left-right direction, and for example, an ellipse-paraboloid 9 as shown in FIG. 4 may be used.

When the normal direction of the ellipse-paraboloid 9 at its center is selected as the X axis, the horizontal axis is the Y axis, and the axis parallel to the z axis is the Z axis, c, d, and e are constants. is expressed by the following formula [Math. 2], the cross-sectional shape is elliptical, and the vertical cross-sectional shape is parabolic.

[0019]

[Math 2]

Reference numeral 10 denotes an area for obtaining a cut line specific to the passing beam with respect to the light distribution pattern (see FIG.
), the angle that the boundary line between regions 3 and 10 makes with the y-axis in the third quadrant (y<0, z<0) of the yz plane is the angle required by the light distribution standard.

FIG. 5 shows a diagram of the optical path between the area 5 of the reflecting mirror 1, and shows the optical path from the coiled filament 11 arranged so that its central axis is along the optical axis (x-axis) to the area 5.
The lights 12, 12, . . . emitted toward the left and right (direction parallel to the y-axis) by the segments 5a, 5a, .
spread to. Note that the rear end of the filament 11 (the end closer to the reflecting mirror) is located near the focal point of the parabolic reflecting region 3.

[0022] Therefore, the concentration of light flux on the lens 13 disposed in front of the reflector 1 (that is, the light reflected from the reflection area around the light bulb mounting hole 4 is prevented from being locally concentrated on the lens 13). The surface temperature at the center of the lens 13 was measured under the same conditions except for the shape of the reflecting mirror.
The temperature using reflector 1 is 10℃ higher than that of the conventional one.
The result was that it was moderately low.

[0023]

[Effects of the Invention] As is clear from the above description, the present invention provides a diffusive reflective area on one part of the reflective surface in order to diffuse the light from the light source that reaches the periphery of the light bulb mounting hole. Since the reflector is formed as a section, the inconvenience that the heat distribution is biased due to the irradiated light with respect to the lens provided on the front surface of the reflecting mirror and a high temperature section is generated can be alleviated. Therefore, since it is possible to use a material that does not require very strict heat resistance for the lens, such as synthetic resin, it is possible to reduce the weight of the lamp.

In the above-mentioned embodiment, the light is diffused in the horizontal direction by the region 5 due to the requirement regarding the light distribution pattern, but the technical scope of the reflector of the vehicle lamp of the present invention is limited to such an embodiment. It should not be construed as being limited to only this, and it goes without saying that it may be diffused in a desired direction, such as the vertical direction, if necessary.

[Brief explanation of the drawing]

FIG. 1 is a front view of a reflecting mirror according to the present invention.

FIG. 2 is a perspective view showing the shape of a hyperbolic paraboloid.

FIG. 3 is a schematic diagram for explaining how to form segments.

FIG. 4 is a perspective view showing the shape of an ellipse-paraboloid.

FIG. 5 is an optical path diagram regarding the reflecting mirror of the present invention.

FIG. 6 is an optical path diagram regarding a conventional reflecting mirror.

[Explanation of symbols]

1 Reflector 2 Reflective surface 4 Bulb mounting hole 5 Reflection area 5a Reflective element 11 Light source

Claims (2)

[Claims] 1. A reflector for a vehicle lamp, characterized in that a reflective area is formed on a reflective surface to diffuse light emitted from a light source that reaches the periphery of a light bulb mounting hole. 2. The reflective region is comprised of a plurality of reflective elements,
2. The reflector for a vehicle lamp according to claim 1, wherein the shape of the reflecting element is a hyperbolic paraboloid or an ellipse-paraboloid.