JP2704578B2 - Headlight for low beam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a headlamp for a vehicle, and more particularly, to a headlamp having a low-beam light distribution characteristic provided exclusively for a low-beam in a four-lamp type headlamp. It is related.

[0002]

2. Description of the Related Art FIG. 4 shows an example of the structure of a conventional low beam headlamp 90 of this kind.
1, a paraboloid of revolution having a focal point f2 in front of the filament 93 is arranged as a lower reflecting surface 91b in the lower half, and the lower paraboloid has a focal point f2. Each reflection surface 91a, 91b
The reflected light does not include upward light, and light distribution characteristics for a low beam can be obtained without providing a hood in the filament 93.

[0005] In an actual implementation, as shown in a front view in FIG. 5, an upward light is applied to a road shoulder side (left side if left-hand traffic) to improve visibility of a road sign or the like. The fan-shaped portion 91c is formed by allowing the reflecting surface 91a to enter the lower reflecting surface 91b side by a predetermined angle (usually about 15 °) to obtain a target upward light by the fan-shaped portion 91c. .

[0004]

However, in the configuration of the conventional low beam headlamp 90 described above, first, as is apparent from FIG. 4, the reflecting mirror 91 is rotated by two surfaces having different focal positions. Since the parabolic surface is compounded, an upward step 91d is generated at the joint thereof, and there is a problem that light of the filament 93 reflected on the step 91d becomes upward dazzling light. .

Second, the provision of the fan-shaped portion 91c allows the spot pattern SU, which is the shape of the light reflected from the upper reflecting surface 91a, to be formed as shown in FIG.
Although only the portion c protrudes on the horizontal line H, the portion corresponding to the fan-shaped portion 91c is missing in the spot pattern SD from the lower reflection surface 91b, and therefore, the portion protruding on the horizontal line H is not so prominent. Illumination cannot be obtained,
There has been a problem that the visibility on the side of the intended road shoulder is insufficient, and solving these problems has been an issue.

[0006] The present invention provides a concrete means for solving the above-mentioned conventional problems as a hoodless filament,
In a low beam headlamp comprising a composite reflecting surface whose respective focal positions are adjusted so as to reflect light from the filament as downward light, the composite reflecting surface has an upper half portion and one of left and right horizontal surfaces. A fan-shaped part which enters the lower half part from the end to the predetermined angle around the axis is formed as a paraboloid of revolution having a focal point behind the filament to be an upper reflecting surface, and the fan-shaped part of the upper reflecting surface is provided. An elliptic paraboloid whose vertical focal point is set in front of the filament and whose horizontal focal point is substantially coincident with the focal point of the upper reflecting surface from the end surface on the side of the non-exposed side to just before the gap having substantially the same angle as the fan-shaped portion. Is formed as a lower reflecting surface, and a parabolic surface whose focal length is gradually changed so as to connect the upper reflecting surface and the lower reflecting surface without generating a step is formed in the gap, and a connecting reflecting surface is formed. To be By providing low beam headlamp, characterized in Rukoto, as not occur any of the above problems, it is to solve the problem.

[0007]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. 1 shows a headlight for a low beam according to the present invention (hereinafter abbreviated as a headlight 1), and a reflector 2 of the headlight 1 is shown in a front view in FIG. Basically, an upper reflecting surface 21 formed of a paraboloid of revolution and a lower reflecting surface 22 formed of an elliptical reflecting surface
And a connecting reflecting surface 23 for connecting the upper reflecting surface 21 and the lower reflecting surface 22 to each other.

In the following, the respective reflecting surfaces 21 to 23 will be described in more detail. First, the upper reflecting surface 21 is composed of the upper half of the reflecting mirror 2 and the left and right horizontal portions of the upper half. A predetermined angle α from the end (the end on the side determined by the traffic rules such as left-hand traffic as described in the conventional example).
A fan-shaped part which enters into the lower half by only (typically approximately 15 °) is formed by a paraboloid of revolution having a focal point F1 behind the filament 3, and the upper reflecting surface 21
Is the same as that of the conventional example.

However, according to the present invention, the lower reflecting surface 22 disposed in the lower half portion is represented by ｛(X ² / 4F _X ) + (Y ²
/ 4F _Y ) = Z｝ and is formed in an ellipsoidal paraboloid, and one end thereof is provided with the fan-shaped portion of the upper reflection surface 21 at one end. Is connected to the end on the other side, but the other end is set up to just before the fan-shaped portion, and the fan-shaped portion is defined by a predetermined angle α ( (Typically, approximately 15 °).

Further, the value of F _{X in} the lower reflective surface 22 is adjusted in the above equation so that a step does not occur at the junction with the upper reflective surface 21, and the value of F _Y is also adjusted. In the vertical direction, a focal point F2 is provided in front of the filament 3 (see FIG. 1), so that no upward reflected light is generated with respect to the light from the filament 3.

In addition, according to the present invention, the connection reflection surface 23 is provided in the gap described above, and this connection reflection surface 23
The focal length is smoothly changed from the focal length of the upper reflective surface 21 to the focal length of the lower reflective surface 22 between the joint portion with the upper reflective surface 21 and the joint portion with the lower reflective surface 22, and each reflection is performed. It is formed as a parabolic surface having a gradually changing focal length that does not cause a step at the junction with the surfaces 21 and 22.

Next, the operation and effect of the headlamp 1 of the present invention having the above-described structure will be described. First, on the upper reflecting surface 21, the spot F1 is located behind the filament 3 because the focal point F1 is located behind the filament 3. As shown in FIG. 3, the pattern S21 is formed as a fan-like shape which is inverted up and down and right and left and spreads below the horizontal line H. At this time, the reflection from the fan-shaped portion formed so as to enter the lower half at a predetermined angle α. The light is emitted as upward light above the horizontal line H, and the angular portion S21 protrudes with an upward slope of the predetermined angle α.
a is formed, and the roadside illumination is performed with the corner portion S21a.

In the lower reflecting surface 22, the vertical focal point F2 is located behind the filament 3, and the horizontal focal point is substantially the same elliptical paraboloid as the upper reflecting surface 21. The spot pattern S22 generated by the lower reflecting surface 22 is inverted only in the left-right direction, and
Of the upper reflecting surface 2
However, at the end on the side where the fan-shaped portion is provided, the reflected light has a defect, and the end face of this portion has a downward slope. .

Further, since the connection reflecting surface 23 is formed as a parabolic surface that smoothly changes from the focal length of the upper reflecting surface 21 to the focal length of the connecting portion of the lower reflecting surface 22, the connection reflecting surface 23 is formed. The spot pattern S23 generated by the reflection surface 23 naturally connects the spot pattern S21 to the spot pattern S22. Specifically, one end is added to the end which becomes an upward slope generated by the fan-shaped portion of the spot pattern S21. And a wedge-like shape in which the other end of the spot pattern S22 is in contact with the other end of the spot pattern S22 that is inclined downward, and exists on the horizontal line H.

This means that the reflected light from the connection reflection surface 23 overlaps the corner portion S21a, and therefore, the portion of the corner portion S21a becomes the upper reflection surface 21 as in the conventional example. This solves the problem that the amount of light is insufficient compared to other portions that are generated only by reflected light from the other and are generated by reflected light that is superimposed from two reflecting surfaces.

In addition, according to the present invention, there is no step in the upper reflecting surface 21 and the lower reflecting surface 22, the upper reflecting surface 21 and the connecting reflecting surface 23, and all the connecting portions between the lower reflecting surface 22 and the connecting reflecting surface 23. As a result, no upward light other than the preset upward light such as the above-described upward light for roadside confirmation is generated, and therefore, dazzling light to oncoming vehicles does not occur.

[0017]

As described above, according to the present invention, the upper half portion including the fan-shaped portion into which the reflecting mirror enters the lower half portion is formed by a paraboloid of revolution having a focal point behind the filament to form an upper reflecting surface. The vertical focus is set in front of the filament from the end face of the upper reflection surface on which the fan-shaped portion is not provided to a position just before the gap having substantially the same angle as the fan-shaped portion, and the horizontal focus is the upper reflection surface. The focal length is gradually changed so as to form an elliptic paraboloid substantially coincident with the focal point of the lower reflecting surface, and to connect the upper reflecting surface and the lower reflecting surface to the gap without generating a step. First, by using a low-beam headlamp with a parabolic surface formed as a connecting reflective surface, it was first used to confirm the roadside, which was conventionally formed with reflected light from the upper reflective surface and lacked illuminance. For upward light, reflection from the connecting reflective surface Even those with and improve the illuminance added to improve the visibility of such a road sign on the road side, in which excellent effects for improving the performance of the headlamp of this type.

Secondly, the above configuration eliminates a step in the reflecting mirror in which a plurality of reflecting surfaces are combined, so that an upward light other than a predetermined upward light such as the above-mentioned upward light for roadside confirmation can be used. Light is not generated at all, and dazzling light to oncoming vehicles does not occur, so that the effect of further improving the performance is achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a low beam 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 light distribution characteristic of the same embodiment as a spot pattern.

FIG. 4 is a sectional view showing a conventional example.

FIG. 5 is a front view showing a main part of a conventional example.

FIG. 6 is a graph showing a light distribution characteristic of a conventional example as a spot pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Headlight for low beam 2 ... Reflecting mirror 21 ... Upper reflecting surface 22 ... Lower reflecting surface 23 ... Connecting reflecting surface 3 ... Filament S21-S23 ... Spot pattern

Claims (1)

(57) [Claims] 1. A low-beam headlight comprising a filament without a hood and a composite reflection surface whose focal position is adjusted to reflect light from the filament as downward light, wherein the composite reflection surface is The upper half portion and a fan-shaped portion that enters the lower half portion to a predetermined angle around the axis from one of the left and right horizontal ends as an axis are formed by a paraboloid of revolution having a focal point behind the filament as an upper reflecting surface, A vertical focus is set in front of the filament from an end surface of the upper reflection surface on the side where the fan-shaped portion is not provided to a position just before a gap having substantially the same angle as the fan-shaped portion, and a horizontal focus is the upper reflection surface. The focal length is gradually changed so as to form an elliptic paraboloid substantially coincident with the focal point of the lower reflecting surface, and to connect the upper reflecting surface and the lower reflecting surface to the gap without generating a step. A headlight for a low beam, wherein a parabolic surface is formed as a connection reflection surface.