JP2704577B2 - Vehicle headlights - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a headlight for a vehicle, and more particularly to a method for forming a light distribution characteristic for a low beam in the headlight.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a conventional method of forming a light distribution characteristic for a low beam in a headlamp 90 of this type. A passing filament 92 is provided in front of the optical axis Z of the reflecting mirror 91, that is, the longitudinal axis is parallel to the rotation axis of the paraboloid of revolution, and the passing filament 92 has a hood 93 covering a lower half. It is supposed to be provided.

With the above configuration, the light from the passing filament 92 is reflected only by the upper half of the reflecting mirror 91, and has a substantially fan-like shape extending downward from the horizontal line H as shown in FIG. A spot pattern S is obtained, and the spot pattern S is diffused in the left and right (horizontal) directions by a lens cut provided on the lens 94, thereby obtaining a light distribution characteristic for a low-pass beam that does not include upward light. It will be something that can be done. In the actual implementation, upward light is applied to either the left or right side of the vertical line V in order to easily confirm the road sign on the shoulder side of the road.

[0004]

However, in the above-mentioned conventional method for forming the light distribution characteristics for a low beam, the spot pattern S is leftward because the reflecting mirror 91 is formed on a paraboloid of revolution. The right side and the lower side are all illuminated at the same irradiation angle. Particularly, the lower side is illuminated from directly below the vehicle, and the road surface on the front side of the vehicle is illuminated very brightly.

[0005] This means that the driver's pupil is narrowed down in accordance with the brightness of the road surface on the near side and the sensitivity is reduced, and the visibility to a distant place that is darker than the road surface on the near side is reduced. In addition to the problem of lowering the efficiency, the problem is that the utilization rate of the luminous flux emitted from the passing filament 92 is reduced as a result of irradiating a portion that is originally not so necessary. Had become something.

[0006]

According to the present invention, as a specific means for solving the above-mentioned conventional problems, there is provided a low beam filament which is parallel to the optical axis of a reflecting mirror in the longitudinal direction and whose lower half is covered with a hood. In the vehicle headlamp adopted, a parabolic column surface in which a parabola appears in a vertical cross section is adopted in the center of the upper half of the reflector, and a rotating paraboloid is adopted in the lower half, An elliptical paraboloid for connecting the parabolic cylinder surface and the rotating paraboloid surface without generating a step is provided on the left and right sides of the upper half part. By doing so, it is possible to obtain an ideal light distribution characteristic as a headlamp and increase the light flux utilization rate to solve the above-mentioned conventional problems.

[0007]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. 1 is a headlight according to the present invention. The headlight 1 includes a reflector 2 and a passing filament 3 whose longitudinal direction is parallel to the optical axis Z of the reflector 2. A hood 4 that covers the lower half of the passing filament 3 and a lens 5 that gives an appropriate lateral spread to a spot pattern generated by reflecting light from the passing filament 3 to the reflecting mirror 2. This is the same as that of the conventional example.

However, according to the present invention, the reflecting mirror 2 is used.
In the front view shown in FIG. 2, a parabolic cylindrical reflector 21 disposed in the center of the upper half of the reflecting mirror 2 and a rotating parabolic reflector 22 disposed in the lower half of the reflector 2 , Are formed as composite reflecting surfaces by elliptical parabolic reflecting portions 23 arranged on the left and right of the upper half, respectively.

Here, the respective portions of the reflecting mirror 2 will be described in more detail. First, the parabolic columnar reflecting portion 21 has a parabolic shape in a vertical cross section and a parabolic shape in a horizontal cross section. It is a pillar surface, and therefore, the passing filament 3
After being reflected by the parabolic columnar reflecting portion 21, the light from the horizontal direction is wide below the horizontal line H, in the horizontal direction, and vertically, as shown by the spot pattern 3-21 in FIG. Has a narrower shape converged more than in the case of the paraboloid of revolution described in the conventional example.

Next, the paraboloid of revolution 22 disposed in the lower half of the reflector 2 will be described. The paraboloid of revolution 22 is a hood that covers the lower half of the passing filament 3. With the provision of 4, the light from the passing filament 3 does not reach, and therefore does not participate in the formation of the light distribution for the passing beam.

The elliptic parabolic reflector 23 has a ｛(X
² / 4F _X ) + (Y ² / 4F _Y ) = Z｝ This is a curved surface represented by the following equation. Since the parabolic column surface portion 21 is provided in the center of the upper half of the reflecting mirror 2, When the rotation parabolic reflector 22 provided in the lower half is directly extended and connected to the parabolic columnar reflector 21, a step is generated. Therefore, the elliptic parabolic reflector 23 is employed. By adjusting F _X and F _Y in the formula, the parabolic cylindrical reflecting portion 21 and the rotating parabolic reflecting portion 22 are connected without generating a step, and at this time, the elliptic paraboloid is used. The spot pattern 3-23 generated by the reflecting portion 23 appears as a substantially fan-shaped shape on both sides of the vertical line V below the horizontal line H as shown in FIG.

In FIG. 1, reference numeral 6 denotes a traveling filament, which is disposed at a position substantially at the focal point of the rotating parabolic reflector 22, and which is turned on when the traveling filament 6 is turned on. As shown in FIG. 4, the spot pattern 6-21 from the parabolic cylindrical reflector 21, the spot pattern 6-22 from the rotating parabolic reflector 22, and the spot pattern 6-22 from the elliptical parabolic reflector 23. As a result, a spot pattern suitable for the light distribution of the traveling beam superimposed on the horizontal line H is obtained.

In both cases where the passing filament 3 is turned on and the traveling filament 6 is turned on, the spot patterns 3-21 and 6-21 are formed by the adoption of the parabolic cylindrical reflecting portion 21. Since the width becomes wider in the left-right direction, it is preferable that the degree of diffusion in the left-right direction of the lens cut made on the lens 5 is smaller than that of the conventional example.

Next, the operation and effect of the headlamp 1 of the present invention having the above structure will be described. The central part of the upper half of the reflecting mirror 2 is formed as a parabolic cylindrical reflecting part 21. The convergence in the vertical direction can be easily increased as compared with the conventional rotating parabolic reflector.
1 can be arranged in the vicinity of the horizontal line H as a narrow vertical width (see FIG. 3).

This naturally increases the amount of light reaching the distant place, and the headlamp 1 improves the visibility in the distant place, but at the same time, the road surface on the front side of the vehicle is illuminated more brightly than necessary. As a result, the pupil of the driver is not narrowed more than necessary, the visibility is kept high, and the visibility to a distant place is improved more than the increase in the amount of the distant light.

In addition, by connecting the parabolic cylindrical reflecting portion 21 and the rotating parabolic reflecting portion 22 with the elliptic parabolic reflecting portion 23, no step is formed at the connecting portion of each reflecting surface. Therefore, it is assumed that stray light due to the step is also prevented from occurring and, for example, dazzling light is not generated. In this embodiment, the upward light irradiating the road shoulder side at the time of the passing beam light distribution is omitted and described. However, this can be added by known means as necessary. Needless to say.

[0017]

As described above, according to the present invention, a parabolic cylindrical surface in which a parabola appears in a vertical cross section is employed in the center of the upper half of the reflector, and a rotating paraboloid is employed in the lower half. Adopted,
On the left and right sides of the upper half, a vehicular headlamp adopting an elliptical paraboloid that connects the parabolic column surface and the rotating paraboloid surface without generating a step is adopted, so that the passing beam Sometimes the parabolic cylindrical surface allows the generation of a spot pattern that is narrower in the vertical direction than the conventional rotating parabolic surface, thereby increasing the amount of light reaching far and requiring a short distance. As described above, it is possible to prevent a decrease in the visibility of the driver due to being brightly illuminated and to increase the visual recognition distance, thereby achieving an extremely excellent effect in improving the performance of this type of headlight.

In addition, since the parabolic cylindrical surface and the rotating parabolic surface are connected by an elliptic paraboloid, no step is formed in the reflecting mirror, and for example, stray light which becomes dazzling light is not generated. The effect that can be prevented is also achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a vehicle headlamp according to the present invention.

FIG. 2 is a front view showing a main part of the same embodiment.

FIG. 3 is a graph showing a spot pattern when the passing filament is turned on in the same embodiment.

FIG. 4 is a graph showing a spot pattern when the running filament of the same embodiment is turned on.

FIG. 5 is a sectional view showing a conventional example.

FIG. 6 is a graph showing a spot pattern when a passing filament is lit in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Headlamp for vehicles 2 ... Reflector 21 ... Parabolic surface reflection part 22 ... Rotation paraboloid reflection part 23 ... Elliptic paraboloid reflection part 3 ... Passing filament 4 ... Food 5 ... Lens 6 ... Running filament 3-21-6-23 ... Spot pattern

Claims (1)

(57) [Claims] 1. A vehicular headlamp employing a low-beam filament that is parallel to the optical axis of the reflector and extends in the longitudinal direction and covers a lower half of the reflector with a hood. A parabolic column surface with a parabola appearing in the vertical section is adopted,
A paraboloid of revolution is adopted in the lower half, and an elliptical paraboloid that connects the paraboloid and the paraboloid of revolution without generating a step is adopted on the left and right of the upper half. A headlight for a vehicle, characterized in that: