JPS6323603B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a parabolic reflector for a headlamp used in a vehicle such as an automobile, and relates to a composite reflector having a plurality of reflecting surfaces. (Prior art) An automobile headlamp reflects a radiant and diverging beam emitted from a light source by a parabolic reflector to form a forward beam, and adjusts the direction of this beam by a cup group of front lenses. The desired light distribution can be obtained. The prism principle is used to correct the direction of the light beam using the cut group of the front lens, and in particular, in order to form left and right expansion, a cylindrical cut that can be regarded as a continuous prism (the cut part becomes a cylindrical concave curved surface) is used. Pieces cut like this) are used in practice. The cut portion of lens piece a is shown in FIG. In this lens piece a, a cylindrical cut b is formed on the inner surface, and when the parallel reflected light beam c reflected by the parabolic reflector is irradiated to the outside through the cylindrical cut b, it is spread to the left and right. Recently, air resistance in cars has become a problem, and headlamps with a large tilt angle θ of the front lens that receives wind pressure have become required. Therefore, when the lens piece a is tilted at a certain angle (θ≦20°), a characteristic of the cylindrical cut b is that the luminous flux projected onto the screen d falls below the horizontal line e on the end side (hereinafter referred to as light It is not possible to set a large angle of inclination because this will result in a phenomenon called sag (referred to as a sagging phenomenon) and the light distribution will not be appropriate. Therefore, there is a limit to how much the light flux can be spread by the cylindrical cut of the front lens, and a reflector has been sought to spread the light flux. As a reflecting mirror that spreads a light beam in the horizontal direction, for example, one disclosed in Japanese Patent Publication No. 145002/1983 is known. In this known reflecting mirror, when a light source is placed near the focal line of the parabolic columnar reflecting mirror, the reflected light spreads in the horizontal direction and substantially in the vertical direction, as shown in Fig. 7. A reflected luminous flux with no reflection can be obtained. The light distribution pattern in this case is the case where there is no lens in front of the reflecting mirror. As is clear from this light distribution pattern, the left and right divergence angle is within 20°, and no light sagging phenomenon is observed. However, in the case of automotive headlamps, it is particularly important to have different light distribution, and the spread angle to the left and right is ±15° according to the standard, but it is desired that the light be distributed up to ±30° in practice. ing. Therefore, when using the known reflecting mirror, there is a problem in that in order to obtain a practical misalignment light distribution, the light flux must be modified by a lens cut by the front lens to form an appropriate misalignment light distribution. In particular, forming a light distribution that is approximately symmetrical with respect to the front as described above is important because each focal length F of the parabolic column is
This appears to be caused by making the curve where the and the tangents at each vertex touch into a parabola, which is the same as the focal length F mentioned above. (Problems to be Solved by the Invention) The present invention aims to solve the problem of the conventional example of correcting the luminous flux of the light distribution pattern with the front lens and the problem of the light sagging phenomenon that occurs when the front lens is installed at an angle. That is. (Means for Solving the Problems) The present invention is a specific means for solving the problems in the conventional example described above. Provided is a composite reflector for a headlamp, characterized in that, in a plurality of reflecting mirrors having parabolic cylindrical reflecting parts, the focal length of each of the parabolic cylindrical reflecting parts is set to increase successively as the distance from the light source increases. ,
As the focal length gradually increases, the horizontal light distribution expands to a required predetermined angular range, eliminating the need for light flux adjustment using a front lens. In addition, in addition to the above configuration, a part or all of each parabolic cylindrical reflection section is configured such that the reflected light in a position range a predetermined distance X away from the side of each parabolic cylindrical reflection section near the light source is directed toward the front. By specifying that the ratio of X and CL is set to be 0.4≦X/CL≦0.6, the effective light emission length of the light source can be changed. Also, the front illumination has the planned light distribution characteristics and no luminescent spots occur. (Embodiment) Next, the present invention will be explained in more detail based on the illustrated embodiment. Reference numeral 1 denotes a rectangular composite reflector having a paraboloidal surface as a whole, and the composite reflector 1 is a reflector of a headlamp. The front lens 2 is attached to the front side. The reflecting surface of the composite reflecting mirror 1 is divided into a plurality of parabolic cylindrical reflecting sections in the vertical direction when viewed from the front, and the sections are divided at the mounting position 3 of the bulb or light source.
It is formed symmetrically around the center. In the illustrated embodiment, the division is divided into eight parts, and each parabolic cylindrical reflection part 1-1 to 1-
It is labeled as 8. The focal length of each of these parabolic cylindrical reflecting portions is gradually increased from the center side toward the side surface side, and each focal length line is set to intersect at one point. By increasing the focal length of each parabolic cylindrical reflection section in this way, the reflected light spreads in the horizontal direction, resulting in a light distribution pattern for the entire reflecting mirror, for example, as shown in Figure 4. . As is clear from this figure, the spread on both sides reaches approximately ±30°, which is ideal. The above light distribution pattern does not pass through the front lens,
This is a pattern in which the reflected light from each parabolic cylindrical reflection section 1-1 to 1-8 is projected directly onto the screen, and a point light source (1φ spherical light source) is placed at the focal point of the reflecting mirror. . In this case, one end (inner side) of the reflected light from each parabolic cylindrical reflection section comes to be caught in the center of the screen. That is, as shown in FIG. 5, the ends of the reflected light 1-1a from the parabolic cylindrical reflection section 1-1 and the reflected light 1-5a from the parabolic cylindrical reflection section 1-5 are centered. Because these parabolic cylindrical reflection parts are arranged symmetrically,
This results in a light distribution pattern that spreads approximately symmetrically on both sides. Also, as is clear from these light distribution patterns, the reflected light reflected by the parabolic cylindrical reflection parts 1-1 to 1-3 near the center, which have short focal lengths, forms a wide light band that widely spreads left and right. The reflected light from the parabolic cylindrical reflection parts 1-5 to 1-8 located on the side faces forms a spot-like light band near the center of the screen, and only these reflected lights This creates an ideal light distribution pattern for a headlamp, and requires almost no adjustment of the luminous flux with a lens. The light source actually used, ie, the bulb 4, is of the C-8 filament type and includes main and sub filaments 5 and 6, as shown in FIG.
The filament is then positioned longitudinally with respect to the reflector and has a substantially constant effective emission length CL. The effective light emitting length of this light source also spreads the luminous flux in the lateral direction. When viewed from the front, each of the parabolic cylindrical reflection parts 1-1 to 1-8, except for the parabolic cylindrical reflection part 1-8 at the end, gradually narrows in width as it moves away from the center, that is, the light source. , the light from the light source located at the focal point is set to the part indicated by the dotted line 7 near the light source of each parabolic cylindrical reflection part, and the light from the light source is set to go to the center of the light distribution pattern, that is, directly in front, and the diagonal line 8 in the vicinity The indicated area is set to form a spot. In this case, the range in which the reflected light directed directly in front is reflected is closely related to the effective light emission length CL of the front light source, so the range must be specified. In other words, the position range that is a predetermined distance X away from the light source side of each parabolic cylindrical reflection section needs to face in the front direction, and the effective light emitting length of the light source also depends on the type of bulb used. For example, in addition to the C-8 filament type, discharge lamps can also be used, so the effective light emitting length CL of the light source itself must be determined. Therefore, the range in which the reflected light is directed toward the front is set so that 0.4≦X/CL≦0.6. In addition, the focal length and width of each parabolic cylindrical reflection section are determined based on the size of the composite reflector in actual use (approximately 180 mm), and the values are shown in Table 1.
Shown below.

【table】

[Table] (Effects of the Invention) As explained above, in the composite reflector according to the present invention, the focal lengths of the parabolic cylindrical reflectors arranged in parallel in the vertical direction are set to be gradually larger as the distance from the light source increases. It is possible to spread the reflected light up to around ±30° in the left and right directions, and this spread is the ideal spread angle for the irradiated light as a headlamp. This has the excellent effect of eliminating the troublesome lens cut. In addition, by gradually increasing the focal length, the entire reflecting mirror can be made into a horizontally elongated elliptical paraboloid with high utilization of light and good reflection efficiency. If the amount of light used is the same as that of the mirror, the reflecting mirror can have a shallow depth. Furthermore, by making the width of the parabolic cylindrical reflection part narrower as it moves away from the light source, and by providing each parabolic cylindrical reflection part with a reflection part facing straight ahead and a spot reflection part, an ideal arrangement for a headlamp has been achieved. A front lens tilt angle of 40 to
Even if the lamp is tilted at a large angle of 60 degrees, no light sagging phenomenon will occur, and an excellent effect can be achieved in that a headlamp that is less susceptible to wind pressure can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a partially cut-away front view of a headlamp using the composite reflector for a headlamp according to the present invention, Fig. 2 is a partially cut-away top view of the same headlamp, and Fig. 3 is a partially cut-away top view of the same headlamp. Figure 1 is a cross-sectional view taken along the - line in Figure 1, Figure 4 is a light distribution pattern diagram of the same composite reflector, and Figure 5 is some light distribution patterns of the reflective part on one side of the parabolic cylindrical reflective part of the same reflector. 6 is a schematic perspective view showing the state of refraction of light in some cylindrical cut pieces formed in the lens, and FIG. 7 is an example of correcting the light flux with a lens in the conventional example. FIG. 5 is a diagram of a light distribution pattern of a reflecting mirror according to the invention of Japanese Patent Publication No. 145002/1982. 1... Compound reflecting mirror, 1-1 to 1-8... Parabolic cylindrical reflection section, 2... Lens, 3... Light source mounting position, 4... Bulb, 5, 6... Filament,
CL...Effective light emission length, X...Distance from the side of the parabolic cylindrical reflection section closer to the light source.

Claims (1)

[Scope of Claims] 1. In a composite reflector having a parabolic cylindrical reflection section that is vertically divided into a plurality of parts on the left and right with the mounting position of the light source as the center, each focal point of the parabolic cylindrical reflection section is provided. A composite reflector for a headlamp, characterized in that the distance is set to increase gradually as the distance from the light source increases. 2. The composite reflector for a headlamp according to item 1, wherein the front view width of the parabolic cylindrical reflecting portion is gradually narrowed as the distance from the light source increases. 3. In a composite reflector having a parabolic cylindrical reflection section that is vertically divided into a plurality of sections on the left and right around the mounting position of the light source, each focal length of the parabolic cylindrical reflection section is separated from the light source. , and the reflected light in a position range a predetermined distance If the effective light emission length of the light source is CL, then
A composite reflector for a headlamp, characterized in that the ratio of X and CL is set to be 0.4≦X/CL≦0.6.