JPH0247523Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a headlamp for an automobile, and in particular, a front lens is provided with a vertical cylindrical prism, and a cylindrical prism element near the center of the front lens is provided. This relates to a headlamp whose center line is inclined relative to the vertical line.

[Conventional technology]

FIG. 5 is a sectional view showing an example of a headlamp. A front lens 2 is attached to the front opening of the lamp housing 1, and the front lens 2 is provided with a cylindrical prism 2a.

A reflecting surface 1a shaped like a paraboloid of revolution is provided on the inner surface of the lamp housing 1, and a light source bulb 3 is installed near the focal point of the paraboloid of revolution.

Due to the overall design of the vehicle to which this headlamp is installed, in the headlamp of this example, the front lens 2 is not perpendicular to the optical axis Z-Z, and the angle φ shown in the figure forms an acute angle. Sloped in shape.

FIG. 6 shows a light distribution pattern when a screen is provided in front of the headlight of this example (FIG. 5) and irradiation is performed.

H-H is a horizontal line drawn on the screen, V-V
is also a vertical line.

A curve abcd shown by a virtual line is a desired light distribution characteristic. In other words, the driving lane side (left side)
illuminates above the horizon H-H as shown in b-c, and on the opposite lane side (right side) illuminates the horizon H as shown in c-d.
It is desirable to irradiate the area slightly below -H in a pattern parallel to H-H.

However, as mentioned above, if the front lens provided with the cylindrical prism 2a is inclined at an acute angle φ, the pattern formed by the light flux passing through the center of the lens will be as shown with spots in FIG. The light distribution characteristic is curved in an upwardly convex shape as shown in zone 4.

In order to correct such a problem, as shown in FIG. 7, the cylindrical lens provided on the front lens 2 is slanted at a portion C near the center. 7th
An enlarged view of the figure is shown in FIG. The angle θ is the slant angle.

FIG. 9A shows a cross section taken along line A-A' in FIG. 8, and FIG. 9B shows a cross-section taken along line B-B' in FIG.

Within one pitch section p of the cylindrical element, the left section l and the right section r of the center line z-z' are symmetrical and form a concave cylindrical surface with a radius _R1 .

[Problems to be solved by the invention] Figure 10 shows the light distribution pattern when the cylindrical prism is slanted as described above.
A is the irradiation zone by the light beam refracted in the section AA' of the slant section in FIG.

For example, the right half of the irradiation zone B has a shape that is in contact with the ideal line c-d as a result of the above-mentioned slant effect, but instead, the left half of the zone B has a shape that hangs downward. The right half of zone A also sag.

For this reason, the drooping tip (shown with spots) forms an area with greater illumination on the near side than the center of the irradiation area in front of the vehicle body. This makes it difficult to see the central part of the irradiation area.

This idea was created in view of the above circumstances.
In a headlamp in which a front lens is provided with a vertical cylindrical prism, and the center line of the cylindrical prism element near the center of the front lens is inclined relative to a vertical line, It is an object of the present invention to provide a headlamp that does not form an excessively bright area.

[Means for solving problems]

In order to achieve the above object, the headlight according to the present invention is provided with a vertical cylindrical prism on the front lens, and the center line of the cylindrical prism element near the center of the front lens is inclined with respect to the vertical line. The headlamp is characterized in that, for each center line of the cylindrical prism elements near the center, at least a portion of one side of the cylindrical prism elements is provided with means for reducing the prism function.

[Effect]

According to the above configuration, the function of the portion of the slanted cylindrical prism that refracts the light beam toward the front of the irradiation area is corrected, so that an excessively bright spot is not formed in front of the irradiation area.

〔Example〕

1 and 2 are cross-sectional views of the slant portion of the cylindrical prism in one embodiment of the present invention, and FIGS. 9A and 9B in the conventional example, respectively.
FIG.

Figures 1 and 2 are symmetrical.

Looking at FIG. 2, with respect to the center line z-z' of any one pitch P' section of the cylindrical prism element, the left half l' has a concave shape with radius R ₁ as in the conventional example (FIG. 9B). It has a cylindrical shape, and the right half r' has a concave cylindrical shape with a radius _R2 larger than _R1 .

That is, the right half r′ is closer to a flat surface than the left half l′,
The refraction performance as a prism is suppressed.

FIG. 3 is an explanatory diagram showing the effect of the above configuration.

The symmetrical irradiation zone 4 shown by the imaginary line is
This is a conventional pattern drawn for comparison and contrast, and corresponds to zone 4 in FIG. 6 (i.e.,
(This shows the case where the cylindrical prism is not slanted.)

The irradiation zone 5 shown by a solid line in FIG. 3 shows a state in which the cylindrical prism is slanted by an angle θ, and the zone 4 is rotated counterclockwise in the figure by an angle θ (zone B in FIG. 10). ).

Furthermore, in the prism-shaped embodiment shown in FIG. 2, the prism function of the right half r' is suppressed, so that within the irradiation zone 5 (FIG. 3),
Left hanging part 5 _-1 (shown with spots)
is no longer formed, the zone 5 is shrunk in the longitudinal direction, and a portion 5 _-2 marked with parallel hatching is irradiated.

FIG. 4 shows an embodiment different from the above, and is a sectional view corresponding to FIG. 2 of the embodiment.

In this example (Fig. 4), the left half l' of the 1-pitch p' section of the cylindrical prism element constitutes a concave columnar surface with a radius of curvature R ₁ , as in the previous example (Fig. 2), and the same pitch section The right half r' of p' constitutes a convex columnar surface with a radius of curvature _R3 . This example (Figure 4)
Effects similar to those of the embodiments described above (FIGS. 1 and 2) can also be obtained.

[Effect of idea]

As detailed above, the present invention is applied to a headlamp in which the front lens is provided with a vertical cylindrical prism, and the center line of the cylindrical prism element near the center of the front lens is inclined relative to the vertical line. This has the practical effect of not forming an area with excessively high illuminance on the front side of the center of the irradiation area.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a cylindrical prism lens according to an embodiment of the present invention, and FIG. 3 is an explanatory diagram of the operation and effect of the above embodiment. Fourth
The figure is a cross-sectional view of a cylindrical prism lens in an embodiment different from the above. FIG. 5 is a sectional view showing an example of a headlamp with an inclined front lens, and FIG. 6 is an explanatory diagram of an irradiation pattern of a conventional headlamp with an inclined front lens. FIG. 7 is a plan view showing an example of a front lens in which the cylindrical prism near the center is slanted, and FIG. 8 is an enlarged detailed view of the portion shown in FIG. 7. 9 shows a cross section of a conventional cylindrical prism lens, FIG. 9A is a sectional view taken along line AA' in FIG. 8, and FIG. 9B is a sectional view taken along line BB' in FIG. FIG. 10 is a chart for explaining the light distribution pattern when the cylindrical prism is slanted. 1...Lamp housing, 2...Front lens,
2a...Cylindrical prism, 3...Light source bulb.

Claims (1)

[Scope of utility model registration request] In a headlamp in which a front lens is provided with a vertical cylindrical prism, and the center line of the cylindrical prism element near the center of the front lens is inclined relative to a vertical line, the center of the cylindrical prism element near the center of the front lens is inclined. A headlamp characterized in that the radius of curvature of the cylindrical surface on the left side of the line is different from the radius of curvature of the cylindrical surface on the right side of the center line.