JPH0337243B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automobile headlamp using an H4 halogen lamp as a light source.

FIG. 1 shows an example of this type of automobile headlamp, in which the filament of an H4 halogen bulb 3 is positioned near the focal point of a reflector 1 having a substantially rotating paralloid shape with a reflective surface 2 formed on its inner surface. In addition, in this example, a lens 4 is arranged at the front opening of the reflector 1.

The H4 halogen bulb 3 includes a main filament 3a and a sub-filament 3b, and generally both filaments have a length along the main optical axis Z-Z, and the main filament 3a is located approximately at the focal point f. Also, the subfilament 3b is installed so as to be located in front of the focal point f.

The light from the main filament 3a mentioned above is mainly used as a main light to illuminate the front when driving at night, and the light from the sub-filament 3b is mainly used as an auxiliary light to illuminate the road in your own lane when you pass an oncoming vehicle. . For this reason, a light shielding member 3c is provided below the subfilament 3b to mask the light directed downward.

In the conventional automobile headlamp configured as described above, the main filament 3a is connected to the reflective surface 2.
Since it is located near the focal point f, the light is reflected as shown by arrows a and b and is projected almost parallel to the main optical axis Z-Z. However, since the subfilament 3b is located in front of the focal point f, the light is reflected as shown by arrows c and d and intersects with the main optical axis Z-Z.
Projected downward. These projected lights (arrows b, d) are diffused by a lens 4 as shown in FIG. 2 and adjusted to a desired light distribution pattern, but as shown in FIG. It is reflected as shown in c and d and concentrated near part A of the lens 4. For this reason, there is a possibility that the vicinity of the A portion of the lens 4 may be heated when the subfilament 3b is turned on.

Furthermore, in the conventional device described above, almost all of the reflected light is directed toward the center of the front, so there is a technical problem in that it is not easy to adjust this into a desired light distribution pattern using a lens. Next, the above problems will be explained in detail.

FIG. 3 shows a conventional reflector composed of a single rotating object surface, and for convenience of explanation, the opposite slopes are placed at the left part P ₁ , right part P ₂ , upper part P ₃ , and center lower part P ₄ Think about it separately. Boundary lines l ₁ , l ₂ , l ₃ , and l ₄ are virtual lines, and 2a is an opening for mounting a lamp.

The reflected light from the main filament 3a forms a light distribution pattern as shown in FIG. Figure 4
E ₁ is the area of light reflected by the left side P ₁ in FIG. Similarly, E _{2 ,} E ₃ , and E ₄ are respectively on the right side P ₂ ,
This is the area of light reflected by the upper part P ₃ and the central lower part P ₄ .

Figure 5 shows the distribution pattern of the reflected light from the subfilament 3b, where E _{1 ,} E ₂ , and E are the areas of the reflected light from the left part P ₁ , right part P ₂ , and upper part P ₃ , respectively. be. As explained with reference to FIG. 1, since the subfilament 3b is masked from below by the light shielding member 3c, there is no light reflected by the central lower part _P4 of the reflector.

The light distribution pattern of the light reflected by the conventional reflector shown in FIGS. 4 and 5 is not very diffused both in the vertical direction and in the horizontal direction. If we try to diffuse the light that is intensively reflected toward the center of the front surface to the left and right using a lens like the one shown in Figure 2 to correct the desired light distribution pattern, we will end up with a highly uneven prism lens. This causes problems such as poor moldability of the lens and increased thickness and weight.

The present invention was devised in view of the above-mentioned circumstances, and in an automobile headlamp using an H4 halogen bulb, a reclefter in the shape of a rotating paralloid, and a lens, the light from the subfilament 3b is concentrated near the center of the lens. It is an object of the present invention to provide a headlamp for an automobile in which there is no risk of overheating the part and the light distribution pattern of reflected light is almost equal to a desired light projection pattern.

When the light distribution pattern of the reflected light becomes almost the desired light projection pattern, it becomes easy to modify the light distribution using a lens, and a thin lens becomes sufficient, which not only makes the lens lighter but also makes it easier to manufacture the lens. We can expect that.

In order to achieve the above object, the automobile headlamp of the present invention has a filament of an H4 halogen bulb located near the focal point of the reflector, and the reflective surface of the reflector is placed in the center. divided into an upper area including the upper part and diagonally upper parts on the left and right, a lower center area, and a lateral area including the left and right parts of the center and diagonally lower parts on the left and right; () The upper area and the central lower area have a parabola in cross section along a vertical plane parallel to the main optical axis, and a horizontal cross section in the direction of rotation of the side area. It is characterized by being configured to form a group of a plurality of arc-shaped curves that are approximately tangent to a parabola that is a cross section of the object surface.

Next, one embodiment of the present invention will be described with reference to FIGS. 6 to 14.

FIG. 6 is a front view of one embodiment of the reflective surface 2' in the automobile headlamp of the present invention, and FIG.
-Y sectional view, and FIG. 8 is the same XX sectional view.

As shown in Figure 6, the reflective surface of the reflector is
Upper area including the upper center and diagonally upper parts on the left and right
P ₃ , the left area P ₁ including the left diagonal lower part, the right area P ₂ including the right diagonal lower part, and the center lower area P ₄ , and each of these parts is divided into the following squares. Consists of surfaces. l ₁ , l ₂ , l ₃ , and l ₄ are the boundaries between different types of reflective surfaces.

The left area P ₁ and the right area P ₂ are collectively called the lateral area and are expressed as P ₁₊₂ . The reflective surface of this side area P ₁₊₂ is formed into a rotating object surface whose rotation axis is the main optical axis Z-Z of the headlamp. Line L shown in Figure 8
is the cut parabola of this parabola of revolution.

The upper area P ₃ and the central lower area P ₄ are each formed as a reflective surface as described below.

The reflective surfaces of the upper area P ₃ and the lower area P ₄ are formed so that their vertical cross section is a parabola, and their horizontal cross section is a curved line consisting of a plurality of circular arcs that are approximately tangent to the parabola L. .

Each of the reflecting surfaces of the reflector configured as above has a parabolic vertical cross section, so the light emitted from the focal point f is reflected in the horizontal direction as shown by the arrows g, g, etc., as shown in Figure 7. Ru. Further, light emitted from the front side of the focal point f is reflected in a direction intersecting the main optical axis Z-Z as shown by an arrow h.

The direction of reflection in the horizontal plane of the light horizontally reflected as described above will be explained in more detail with reference to FIG. Since the reflective surfaces of the side area P ₁₊₂ are rotational object surfaces, the light emitted from the focal point f and reflected by these surfaces is almost parallel to the principal optical axis Z-Z as g', g'... reflected.

The reflective surfaces of the upper area P ₃ and the central lower area P ₄ are:
Since its horizontal cross section forms a group of arcuate curves, the part that is reflected toward the center of the front as shown by arrow _h1 due to the reflection point will also be reflected inward as shown by arrow _h2 . Also, as shown by the arrow _h3 , some parts are reflected outwardly, and as a result, the reflected light is diffused in the left and right directions.

FIG. 9 is a vertical cross-section of an automobile headlamp provided with a reflector constructed as described above.

FIG. 10 shows a light distribution pattern of the subfilament light produced by the reflector configured as described above. Areas E _{1 and} E 2 of the reflected light from P ₁ and P ₂ , which are parabolic surfaces of rotation, face almost directly in front, and area E ₁ forms a cut line L ₁ on the left, and area E ₂ forms a cut line L ₁ on the right. A cut line L ₂ is formed,
In addition, the area _E3 of the reflected light by the reflective surface _P3 is diffused to the left and right, slightly downward from the horizontal, and the reflected light before entering the lens has almost the desired light distribution pattern. Here, the reason why the area E ₃ is diffused from side to side is because the lights of the arrows h ₂ and h ₃ are diffused as shown in FIG. Also, the reason why the light goes slightly downward from the horizontal is that, as shown in Figure 7, the light goes horizontal as shown by the arrow g that exits the focal point f, but the light that comes out from the sub-filament, which is located slightly in front of the main filament, This is because it points downward as shown by the virtual line arrow h.

FIG. 11 shows a light distribution pattern of light emitted from the main filament 3a. Since the main filament is located near the focal point f, the light is reflected almost horizontally, but the reflected light area E ₃ by the upper area P ₃ and the reflected light area E ₄ by the central lower area P ₄ are diffused left and right.

The lens shape is set so as to diffuse the reflected light of the subfilament shown in FIG. 10 and prepare the light distribution pattern of the auxiliary projection light as shown in FIG. 12.

Luminous fluxes I ₁ , I ₂ , and I ₃ are prepared using reflected light from areas E _{1 ,} E ₂ , and E ₃ , respectively. As mentioned above, the first
Since the light distribution pattern shown in FIG. 0 is almost the desired light distribution pattern, it is sufficient to modify the lens slightly, and therefore, the objective can be sufficiently achieved using a thin lens.

When the reflected light from the main filament shown in Fig. 11 is diffused by the lens set as above, a light distribution pattern as shown in Fig. 13 is obtained, with an appropriate hot line and appropriate left and right spread. The nearly horizontal light beam provides excellent main illumination.

Next, details of the design of the reflecting surface 2' in the above embodiment will be explained with reference to FIG. 14. This figure is an enlarged view of the cross section shown in FIG. 8, with the details of the optical path drawn in.

The reflecting surface in the _P3 area is formed symmetrically with respect to the principal optical axis Z-Z. For convenience of explanation, a large number of curved surfaces constituting the reflective surface of the P ₃ area are named p ₁ , p ₂ , p ₃ to _{p 14} in order from the center.

The central portions p ₁ , p ₂ , and p ₃ are constant diffusion surfaces, and have a larger diffusion rate than the other portions (p ₄ to _{p 14} ).
The lower central area _p4 is also composed of a similar curved surface. Then, the spreading factor is configured to decrease successively from p ₄ to p ₁₄ .

In this example, the arrow added to the p ₂ part on the right side
h′ ₁ represents the optical path of the light emitted from the focal point f and reflected at the center of the portion p ₂ , and arrows h ₂ ′ and h ₃ ′ represent the optical paths of the light reflected at the right and left ends of the portion p ₂ , respectively. ing. Intersection angle (diffusion angle) α between arrow h ₂ ′ and arrow h ₃ ′
is set to α=30° in the portions p ₁ to _{p 3} and set to α=5° near the outermost portion p ₁₄ .

The relationship among the above-mentioned diffusion angle α, the arrangement pitch p of each portion P ₁ to _{P 14} , and the radius r of these curved surfaces is expressed by the following equation.

r=1/2sinα/2×p Therefore, to set α=30℃ as mentioned above, r
It is sufficient if the condition ≒1.9×p is satisfied. As a result, for example, if the pitch p=8 mm, the radius of curvature r
It is sufficient to set r≒1.9×8=15.2mm.

Also, if we try to set α=15° in part _P8 , then r=3.8×p, and by substituting pitch p=8mm into this equation, we get r≒
30.4mm is obtained.

Similarly, considering the case where α=2° at p ₁₄ at the end, r=228.8 mm is obtained from r=28.6×p.

In the embodiment shown in FIG. 14, the arcs appearing in the horizontal cross section of each part of p ₁ to _{p 14} are formed so as to be concave toward the front of the headlight, and each of these arcs forms a parabola as shown in the figure. It is configured so as to be almost in contact with U. However, the above parabola U is a horizontal section of the paraboloid of rotation of the side area P ₁₊₂ .

When practicing the present invention, many of the above (in the preceding examples)
14×2=48) circular arcs may be configured to be convex toward the front. In this case as well, each arc is constructed so as to be substantially in contact with the parabola U.

Next, a modification of the present invention will be explained with reference to FIG. This figure shows a state in which the reflective surface constituting the reflector is cut along a vertical plane parallel to the principal optical axis Z-Z.

Curve Q ₁ represents the vertical section of the reflective surface in the above embodiment. As already mentioned, this curve _Q1 is a parabola whose axis of rotation is the main optical axis Z--Z of the headlamp.

Consider a large number of circles with radius R ₁ inscribed in the parabola Q ₁ above, and find the envelope Q ₂ of the center point O ₁ of each circle.
In this modification, the vertical cross section of the reflector is formed so that the arc represented by the above envelope is concave toward the front of the headlamp, and each of these arcs is approximately in contact with the illustrated parabola U. It is structured as follows.
However, the above parabola U is a horizontal section of the paraboloid of revolution of the side area P ₁₊₂ .

When practicing the present invention, many of the above (in the preceding examples)
14×2=48) circular arcs may be configured to become convex toward the front. In this case as well, each arc is configured so as to be substantially in contact with the parabola U.

In the above example, the radius r of the arcs of P ₄ and P ₅ , P ₅ and P ₆ , etc. is changed, and the diffusion angle α is made smaller as it goes outward, but this is not limited to this. , for example, P ₄ and P ₅ , P ₆ and P ₇ , etc., two radii r
It may be configured such that the diffusivity is kept the same and the diffusion rate decreases as it goes outward.

Next, a modification of the present invention will be explained with reference to FIG. This figure shows a state in which the reflective surface constituting the reflector is cut along a vertical plane parallel to the principal optical axis Z-Z.

Curve Q ₁ represents the vertical section of the reflective surface in the example described above. As described above, this curve _Q1 is a parabola whose rotation axis is the main optical axis Z-Z of the headlamp.

Consider a large number of circles with radius R ₁ inscribed in the parabola Q ₁ above, and find the envelope Q ₂ of the center point O ₁ of each circle.
In this modification, the reflector is formed so that its vertical cross section corresponds to the above-mentioned envelope _Q2 . If we observe this three-dimensionally, if we roll a sphere of radius R ₁ while touching the inner surface of paraboloid Q' ₁ (not shown), the trajectory plane Q ₂ drawn by the center point O ₁ ' of this sphere ′ (not shown). This locus surface Q ₂ ' forms a cubic curve in the form of a paraboloid contracted in the normal direction. This reflector having a reflective surface called the locus surface Q ₂ ' has the same functions and effects as those of the above-mentioned embodiments.

As described in detail above, the present invention is applied to an automobile headlamp that uses an H4 halogen bulb, a paraboloid of revolution reflector, and a lens, so that the light from the subfilament is concentrated in the center of the lens. This has an excellent practical effect in that it eliminates the risk of overheating the part, and also makes it possible to use a thin lens by making the light distribution pattern of the reflected light almost equal to the desired light projection pattern.

[Brief explanation of drawings]

Figures 1 to 5 show one example of a conventional automobile headlamp.
For example, FIG. 1 is a vertical sectional view, FIG. 2 is a front view of a lens, FIG. 3 is a front view of a reflector, and FIGS. 4 and 5 are charts showing light distribution patterns. Figures 6 to 14 show one of the automobile headlights of the present invention.
6 is a front view of the reflector, FIG. 7 is a YY sectional view of FIG. 6, and FIG.
-X sectional view, Fig. 9 is a vertical longitudinal sectional view, Fig. 10 is a chart showing the light distribution pattern of light reflected from the sub-filament, and Fig. 11 shows the light distribution pattern of light reflected from the main filament. Figure 12 is a diagram showing the light distribution pattern of the projected light flux due to the light of the subfilament, Figure 13 is a diagram showing the light distribution pattern of the projected light flux due to the main filament light, and Figure 14 is a horizontal cross section of the reflector. FIG. 15, which is a diagram with optical paths added thereto, is an explanatory diagram of a modification of the present invention. 1... Reflector, 2, 2'... Reflective surface, 3...
...H4 halogen bulb, 3a...same main filament, 3b...same subfilament, 3c...
The same light shielding member, 4...lens.

Claims (1)

[Claims] 1. In an automobile headlamp in which a filament of an H4 halogen bulb is located near the focal point of a reflector, the reflective surface of the reflector includes an upper center and diagonally upper left and right parts. A front for an automobile, characterized in that the front area is divided into an upper area, a lower center area, and a side area including left and right parts of the center and diagonally lower parts on the left and right, and each of these areas is configured as follows. Lighting. () Said lateral area is constituted by a paraboloid of revolution. () The upper area and the lower central area have a parabola in cross section along a vertical plane parallel to the optical axis,
Further, the horizontal cross section is configured to form a group of a plurality of arcuate curves whose horizontal cross section is substantially in contact with a parabola that is a cross section of the paraboloid of revolution of the side area.