JPS6236163Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automotive lamp, and in particular, an automotive lamp with an improved lens shape so that the light beam reflected by a reflector can be refracted so as to be almost uniformly distributed in the front illuminated area. It is related to lighting equipment.

Conventionally, lighting devices such as headlights and fog lamps for illuminating the road ahead of a motor vehicle have a reflector 1 formed into a paraboloid of revolution or a similar shape, as shown in FIG. A structure is used in which a light bulb 2 is provided as a light source near the focal point f, and a lens 3 is attached to cover the front opening of the reflector 1. In the automobile lamp illustrated in this figure, a cylindrical prism 4 is integrally formed on the inner surface of the lens 3. The light emitted from the filament 2a of the light bulb 2 is reflected by the reflector 1, enters the lens 3 almost parallel to the optical axis It is diffused in the horizontal direction (vertical direction in this figure).

FIGS. 2 and 3 are cross-sectional views of a conventionally commonly used cylindrical prism taken along a plane perpendicular to its axis.

The cross-sectional shape of the cylindrical prism shown in FIG. 2 forms a group of continuous concave curves consisting of a plurality of arcs of radius r ₁ that are centered on the straight line l ₁ and arranged so as to touch each other. In addition, the cross-sectional shape of the cylindrical prism shown in Fig. 3 is formed by alternately touching a circle with a radius r ₂ centered on the straight line l ₂ and a circle with a radius r ₃ centered on the straight line l ₃ . It forms a waveform consisting of a continuation of a convex portion of r ₃ and a concave portion of arc r ₂ .

FIG. 4A shows an example of the light distribution pattern of the light beam refracted by the cylindrical prism shown in FIG. 2, where H-H is the horizontal axis and V-V is the vertical axis. FIG. 4B is a chart showing the luminous intensity distribution on the horizontal axis H-H, and the numbers appended to the H-H axis indicate the divergence angle with respect to the optical axis. In this way, the light distribution pattern of a conventional cylindrical prism (Figure 2), which has a cross-sectional shape of a group of continuous concave curves, has a large luminous intensity at the center and a small luminous intensity at the periphery, resulting in an uneven light distribution. .

5A shows the light distribution pattern of the light beam refracted by the cylindrical prism shown in FIG. 3, and FIG. 5B shows the luminous intensity distribution. In this way, the light distribution pattern of the conventional cylindrical prism (Fig. 3), which has a wave-shaped cross-sectional shape in which concave and convex arcs are successively arranged, produces a maximum point e in the center, and Light pools g and g' are formed around the periphery of the light, and the light distribution is non-uniform.

The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to provide an automotive lamp equipped with a lens that can uniformly diffuse a luminous flux over a wide range.

_In order to achieve the above object, _the automotive lamp of the present invention improves the conventional cylindrical prism shown in FIG. It is configured in a special cylindrical prism shape with a cross-sectional shape that is not continuous with the two arcs, but is continuous with a gentle arc (with a large radius of curvature) between the two arcs. Specifically, in an automotive lamp, a light source is provided near the focal point of a reflector having a reflecting surface in the shape of a substantially paraboloid of revolution, and a lens is attached to cover the front opening of the reflector, wherein at least a portion of the surface of the lens is provided. is formed into a cylindrical prism shape in which convex portions and concave portions are continuous in a waveform, and the waveform formed by the cut surface perpendicular to the axis of the cylindrical prism-like portion is (a) each concave portion corresponding to the bottom of the waveform. has a constant radius of curvature (e.g. r ₄ ) larger than the radius of curvature of each convex portion, and (b) each convex portion corresponding to the top of the waveform has a constant radius of curvature (e.g. r ₅ ) smaller than the radius of curvature of each concave portion. ), and (c) the concave and convex portions are configured to form a shape in which they are continuously connected by a gentle arc (an arc with a radius of curvature larger than r ₄ and r ₅ ). shall be.

Next, an embodiment of the present invention will be described with reference to FIG. This figure shows a cross section of an improved example of the conventional cylindrical prism shown in FIG. 3. curve 5
is a waveform formed by a cut surface of a cylindrical prism surface.

The part corresponding to the bottom of the waveform curve above is the radius
It forms a concave arc with radius r ₄ , and the portion corresponding to the wave crest forms a convex arc with radius r ₅ . In addition, both the concave and convex arc-shaped portions are not directly continuous, but are formed by touching a gentle arc with a radius of curvature _r6 between them. The radius of curvature r ₆ described above is made much larger than the radii of curvature r ₄ and r ₅ described above. When carrying out the present invention, good results are likely to be obtained if the dimension of r ₆ is at least twice as large as r ₄ and r ₅ . Also r ₆
This does not preclude making the arc infinite, that is, connecting both arcs with a straight line.

In the embodiment shown in FIG. 6, the center point of the circular arc with radius r ₆ is located outside the waveform curve 5 (on the outer surface side of the lens), but as shown in FIG.
The center point of the arc r ₆ ' may be located inside the lens from the waveform curve 5.

FIG. 8 is an optical path diagram when parallel light beams, arrows h, i, j...z, are incident on the special cylindrical prism shown in FIG.

For example, parallel light beams incident on the slopes of the convex cylindrical portions as indicated by arrows h, i, k, and l are refracted in the converging direction, and after passing through the converging point F, arrows h', i',
It is diffused as k′, l′. However, the light arrow j incident on the center of the top travels straight.

Also, for example, the parallel light beams incident on the slope of the concave columnar part as shown by the arrows o, p, r, s are shown by the arrows o', p',
It is diffused as r′, s′. However, the light arrow q incident on the center of the bottom travels straight.

For example, as shown by arrows m and n, the light incident on the above-mentioned gentle arcuate portion (portion with radius of curvature r ₆ ) travels through each of the above-mentioned optical path arrows h', i', k', l', o', p′,
The reason for this is that, as is clear from this figure, this gentle arc-shaped portion (the portion with a radius of curvature r ₆ ) is larger than the wave crest and wave bottom of the wavy curve 5. This is because the inclination is steep (more specifically, it is greatly inclined with respect to the plane perpendicular to the incident light arrows h to z). In the example, the part with radius of curvature r ₆ ) causes the incident parallel light beam to be largely refracted.As a result, the amount of refracted light beam in the direction close to the optical axis decreases, and the light beam is deflected to the left or right with respect to the optical axis. The refracted light flux increases, and a substantially uniform light distribution pattern can be obtained over a wide angular range.

9A shows a light distribution pattern in the embodiment of FIG. 6, and FIG. 9B shows a light intensity distribution along the H-H axis. In this way, by using the lens formed with the special cylindrical prism of this example, a uniform light distribution pattern can be obtained over a wide angle (approximately 40 degrees on each of the left and right sides in this example). The light distribution pattern and luminous intensity distribution in the embodiment shown in FIG. 7 are also substantially the same as those in FIGS. 9A and 9B.

FIG. 10 is a front view of the lens 3' in this embodiment, in which the above-mentioned special cylindrical prism is provided over the entire surface. As described above, the lens provided with the special cylindrical prism on its entire surface according to the present invention is suitable for use as an automobile headlamp or fog lamp.

11 and 12 each show an application example of the present invention, in which a special cylindrical prism S is formed by applying the present invention to a part of the lens surface. In an automobile headlamp, depending on the filament shape of the light source lamp, the special cylindrical prism of the present invention can be provided on a part of the lens surface as in this application example. The lens shown in Figure 11 is suitable for a head lamp using a C-6 type halogen lamp, and
The lens shown in Figure 2 is suitable for a headlamp using a C-8 type halogen lamp. Also, the 11th
As shown in the figure, the lens having the special cylindrical prism of the present invention on its entire surface can be applied to various types of halogen lamps including C-6 type and C8 type.

As described in detail above, according to the present invention, the projected light of the automobile lamp can be uniformly diffused over a wide angular range.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of an example of a conventional automobile lamp having a paraboloid of revolution reflector, and Figs. 2 and 3 are enlarged views showing examples of lenses used in the above-mentioned automobile lamp, respectively. FIG.
FIG. 4A is a chart showing the light distribution pattern of light diffused by the lens in FIG. 2, and FIG. 4B is a chart showing the same luminous intensity distribution. FIG. 5A is a chart showing the light distribution pattern of light diffused by the lens shown in FIG. 3, and FIG. 5B is a chart showing the same luminous intensity distribution. 6 and 7 are enlarged sectional views of lenses in an embodiment of the present invention, respectively, and FIG. 8 is an optical path diagram in the embodiment of FIG. 6. FIG. 9A is a chart showing the light distribution pattern in the above embodiment, and FIG. 9B is a chart showing the luminous intensity distribution. FIG. 10 is a front view of the lens in the above embodiment, and FIGS. 11 and 12 are front views of the lens in an applied example of the present invention. 1...Reflector, 2...Light bulb as a light source,
2a...same filament, 3,3'...lens,
4... Cylindrical prism, 5... Waveform curve, f...
Focus of the reflector.

Claims (1)

[Claims for Utility Model Registration] An automotive lamp comprising a light source provided near the focal point of a reflector having a reflecting surface in the shape of a substantially paraboloid of revolution, and a lens attached to the reflector so as to cover its front opening. At least a part of the surface of the lens is formed into a cylindrical prism shape in which convex portions and concave portions are continuous in a waveform, and the waveform formed by the cut surface by the plane perpendicular to the axis of the cylindrical prism portion has the following shape. An automobile lamp characterized in that it is configured to perform the following. (a) Each concave portion corresponding to the bottom of the waveform has a constant radius of curvature larger than the radius of curvature of each convex portion. (b) Each convex portion corresponding to the top of the waveform has a constant radius of curvature smaller than the radius of curvature of each concave portion. (c) The convex curve at the top and the concave curve at the bottom are continuously connected by an arc with a radius of curvature larger than the radius of curvature of the convex and concave portions.