JPH02803Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lens for an automobile headlamp.

[Prior art]

Automobile headlamps generally have a light source bulb placed near the focal point of a paraboloid of revolution reflector, and the light that enters the reflector from the light source bulb is reflected as a nearly horizontal parallel light beam, and this horizontal parallel light beam is diffused by a lens. , which distributes light to obtain a desired light distribution pattern.

FIG. 4 shows an example of the required light distribution pattern. This diagram is a simplified isoluminance curve when the optical axis of the headlamp is set horizontally and a screen placed in front of the headlamp is illuminated.

H--H indicates a horizontal line, and V-V indicates a vertical line, and the intersection Z thereof corresponds to the point where the extension of the optical axis of the headlamp intersects the screen.

The characteristics required for a light distribution pattern are to brightly illuminate the road surface on which the vehicle is traveling, not to dazzle oncoming vehicles, and to be able to illuminate other vehicles approaching intersections and pedestrians on the sidewalk. In principle, the area below the horizontal line H-H should be irradiated with a relatively wide width W so that the area can be illuminated.

b The cut portion C on the self-travel line side (left side in this example) should also illuminate slightly above the horizontal direction. and c. A hot zone h with high illuminance may be formed slightly downward from the horizontal direction and near the center in the traveling direction.

In order to obtain the above-mentioned light distribution characteristics, the conventional lens 1 has a cut portion 1a, a large diffuser portion 1b as shown in FIG.
is provided. FIG. 6 shows a negative cross-section in FIG. 5, and FIG. 7 shows a negative cross-section in FIG. 6, respectively.

The cut portion 1a and the large diffusion portion 1b of this example and the conventional example are each constituted by a cylindrical prism, and the light beam modulated by the cut portion 1a of the lens 1 forms a cut portion C on the light distribution chart.

In addition, the light flux modulated in the half part of the large diffuser 1b forms a light distribution zone 2u shown in the actual battle on the light distribution chart, and the light flux modulated in the lower half of the large diffuser 1b forms the light distribution zone 2u shown in the actual battle on the light distribution chart. A light distribution zone 2d indicated by a broken line is formed on the light diagram.

However, since there is no clear boundary between the upper half and the lower half of the large diffusion section 1b, the above-mentioned light distribution zones 2u and 2d are intended to explain this tendency. There is a stepless transition between zone 2u and zone 2d.

[Problem that the invention attempts to solve]

When the light distribution pattern shown in FIG. 1 is formed using the configuration described above, the hot zone h near the center of the vehicle in the driving direction and slightly below is irradiated with high illumination, so that the driver can see the area below the hot zone (road surface). It feels like there is a dark area D (shown with spots) on the front side (in the above example).

This portion D does not have a low illuminance even when measured with an illuminance meter, and it is a matter of the driver's sense, but it is not preferable because it gives a sense of uneven light distribution.

An object of the present invention is to provide a lens for a headlamp that increases the illuminance of the portion D that feels dark and forms a light distribution pattern in which the driver does not feel uneven light distribution.

[Means for solving problems]

In order to achieve the above object, the lens of the present invention is configured such that the upper half of the large diffusion part has a lower wall thickness larger than that of the upper part to refract incident light downward, and The lower half of the large diffusing section is characterized in that the thickness of the lower half is thinner than that of the upper part so that incident light is refracted upward. However, in the present invention, the large diffusion section refers to an area in which a cylindrical prism is arranged to diffuse the parallel light beam incident near the upper part of the center of the lens to the left and right to form an almost horizontally elongated light distribution zone. shall be taken as a thing.

[Effect]

With the above configuration, the light distribution zone formed by the light incident on the upper part of the large diffusion part moves downward, and the light distribution zone formed by the light incident on the lower part of the large diffusion part moves downward. moves upward to increase the illuminance of the area below the hot zone (portion D that felt dark in the conventional example), thereby eliminating the perception of uneven light distribution below the hot zone.

〔Example〕

FIG. 3 shows a lens 3 in one embodiment to which the present invention is applied, and is an explanatory diagram corresponding to FIG. 5 in the conventional example. Fig. 1 shows its cross section.

The cut portion 3a shown in FIG. 3 is a similar component to the cut portion 1a in the previous example, and forms a cut portion light distribution zone C on the light distribution chart.

The large diffusion part to which this invention is applied (see Figure 3) is divided into an upper part 3 _b-1 and a lower part 3 _b-2 , and as shown in Figure 1, the upper part 3 _b-1 becomes thicker toward the bottom. As shown, the thickness of the lower part 3 _b-2 is changed so that it becomes thinner toward the bottom. Z-Z indicates the optical axis. t is a step at the boundary provided for convenience of prism lens design.

FIG. 2 shows an embodiment different from the above (FIG. 1). In this example, there is no step between the upper part 3b _-1 ' and the lower part _b-2 ', and the boundary portion is continuous with a smooth surface (smooth line in the cross-sectional view).

With the above configuration, the light incident on the large diffuser upper part 3b _-1 is diffused in the left and right direction (perpendicular to the page in the figure) as shown by the arrow A in Figure 1, and is also directed downward as shown by the arrow B. be refracted. For this reason,
The light modulated by this large diffuser upper part 3 _b-1 is reflected in the light distribution zone 4u shown in the actual battle on the light distribution chart (Figure 3), and in the light distribution zone 2u of the conventional example (Figure 5).
move downwards.

Also, as shown by the arrow C in Fig. 1, the lower part of the large diffusion part 3 _b-
The light incident on ₂ is diffused in the left-right direction (perpendicular to the page) and refracted upward as shown by arrow D.
For this reason, the light modulated by the large diffuser lower part 3 _b-2 is reflected in the light distribution zone 4d indicated by the broken line on the light distribution chart (Figure 3), as shown in the conventional example (the light distribution zone in Figure 5). 2d and overlaps with the light distribution zone 4u, increasing the illuminance immediately below the hot zone.Therefore, the driver does not feel uneven light distribution, such as when the lower part of the hot zone appears dark.

[Effect of idea]

As described in detail above, when the present invention is applied, there is no longer a phenomenon in which the driver feels that there is a dark area immediately below the hot zone, and there is a practical effect that the driver no longer feels uneven light distribution.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram in which an optical path diagram is attached to a cross section of a lens in one embodiment of the present invention, and the −
Corresponds to a cross-sectional view. FIG. 2 is a sectional view of a lens in an embodiment different from the above. FIG. 3 is a diagram illustrating the functions and effects of the embodiment of the present invention, in which the front view of the lens and the light distribution chart correspond to each other. Figure 4 is a chart showing the light distribution pattern by head lamps.
FIG. 5 is an explanatory view of the function of the conventional lens, showing a front view of the lens and a light distribution chart corresponding to each other. FIG. 6 is a cross-sectional view taken from FIG. 5, and FIG. 7 is a cross-sectional view taken from FIG. 6. 3... Lens configured by applying the present invention, 3a
...Cut part of the above lens, 3 _b-1 ... Also the upper part of the large diffusion part, 3 _b-2 ... Also the lower part of the large diffusion part,
4d, 4u...Light distribution zone.

Claims (1)

[Scope of utility model registration request] In a headlamp lens in which a large diffuser using a cylindrical prism is provided near the center above the lens surface, the upper half of the large diffuser has a lower wall thickness larger than that of the upper part to block incident light. A headlamp characterized in that the headlamp is configured to refract the incident light downward, and the lower half of the large diffusing part is made thinner than the upper part so that the incident light is refracted upward. lens for.