JPH03122902A - Heat lamp for car - Google Patents

Abstract

PURPOSE:To suppress generation of spectral colors on the cutoff line and relieve excessive difference between bright and dark by forming minute recesses and protrusions on that surface of a projection lens on its side where the beams of light are emitted, and thereby diffusing part of the light emitted from the lens. CONSTITUTION:A projection lens 20 is made of glass, whose surface on the side where beams of the light are incident (bulb 12 side) is made flat, while the surface on the beam emission side is made spherical in macroscopic view, wherein the surface of spherical form 21 was subjected to processing for minute recesses 23 and protrusions 22. When emitted from this minute recess/protrusion surface uniformly distributed on the lens surface, part of the light emitted from this projection lens 20 is diffused in different directions. Thereby the density of mono-color concentrated in one place by chromatic abberation is sunk in an amount corresponding to the light diffused, and no color spectrum along the cutoff line will appear any more. Further, too vivid difference between bright and dark at the cutoff line should be relieved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a light source at the first focal point of an elliptical reflector, and a shade for forming a cutoff line near the second focal point of the elliptical reflector. With.

The present invention relates to a (projector-type) automobile headlamp that distributes reflected light from an elliptical reflective layer in a predetermined direction forward through a projection lens, and particularly relates to a projector-type automobile headlamp that is effective in reducing chromatic aberration.

[Prior Art and Problems to be Solved by the Invention] Fig. 3 is a diagram showing an outline of the optical system of this type of headlamp. The light source provided at the focal point, numeral 4 is a projection lens placed in front of the elliptical reflection @2.

Reference numeral 6 denotes a shade for forming a cutoff line, which is provided at the second focal position of the elliptical reflecting mirror 2 and at the focal position of the projection lens 4. Then, the light source light is reflected by the elliptical reflection 1tt2, turned into substantially parallel light by the projection lens 4, and distributed forward, so that a predetermined light distribution with a cutoff line that follows the shape of the upper edge of the shade 6 is obtained. It has become. This type of headlamp has recently attracted particular attention because it is more compact, provides a larger amount of light, and has a sharper cutoff line than a headlamp that uses a parabolic reflector.

However, as a projection lens, a thick single convex lens with a large aperture is generally used.
As shown in Rg (green light) t Qr (red light), when light exits from the projection lens 4, chromatic aberration occurs due to the difference in refractive index of each monochromatic light that is a component of the same light beam that enters the lens, and the sign A blue light is illuminated on the screen indicated by P□, and the symbol p2. Green light and red light are respectively illuminated on the screen indicated by p3. For this reason, as shown in FIG. 4, these spectral colors appear in a region 8 above the cutoff line 7 of the light distribution pattern along the cutoff line 7, making it difficult to see the road surface.

Furthermore, one of the characteristics of projector-type headlamps is that they provide a clear cutoff line, but the fifth
As shown in the doujin curve, compared to the 8 curves showing the characteristics of a parabolic reflector type headlamp, the difference in brightness at the cut-off line is significant, that is, the cut-off line is too clear, making it difficult to see objects on the cut-off line. There was also the problem.

Furthermore, for the driver of an oncoming vehicle, there is a problem in that when the line of sight is in the red part of the spectrum color, the light from the headlamp appears to be red light, and when the line of sight is in the blue part, it appears to be blue light.

The present invention has been made in view of the problems of the prior art,
The purpose is to provide an automobile headlamp that can suppress the occurrence of spectral colors on the cut-off line and alleviate excessive brightness differences on the cut-off line.

[Means to solve the problem]

In order to achieve the above object, an automobile headlamp according to the present invention includes an elliptical reflector and a first part of the elliptical reflector.
A light source provided near a focal point, a shade for forming a cutoff line provided near a second focal point of an elliptical reflecting mirror, and in front of the shade.

In an automobile headlamp, the vehicle headlamp is provided with a projection lens arranged such that the shade is at a focal position and that converts light reflected by an elliptical mirror into parallel light and distributes the light in a predetermined direction in front of the vehicle, in which light from the projection lens is emitted. A finely uneven surface is formed on the side surface to disperse part of the light emitted from the lens.

Possible shapes of the micro-asperity surface formed on the lens surface include satin-like micro ridges, spherical asperities, and the like. The size of the micro-irregularities, that is, the roughness of the lens surface, is determined for optical reasons when the micro-irregularities are formed by polishing, and for optical reasons and strength reasons when the micro-irregularities are formed by molding. Therefore, the particle size of the abrasive used is #3
In the range of surface roughness corresponding to 2o to 1000, particularly surface roughness corresponding to an abrasive grain size of around #400 is most desirable. On an uneven surface having a surface roughness rougher than the surface roughness corresponding to particle size #320, much of the light emitted from the lens is dispersed in directions other than the predetermined direction, that is, the light is excessively scattered.

The cutoff line becomes unclear and the amount of light decreases. In addition, when forming minute irregularities by molding,
Residual strain remains during molding of the uneven surface, resulting in non-uniform refractive index and insufficient lens strength. Therefore, #320 is a range that provides a clear cutoff line, a sufficient amount of light distribution, and is free from the influence of residual distortion in the case of molded lenses.
The roughness of the surface was higher than that corresponding to an abrasive material.

On the other hand, if the uneven surface is finer than the surface roughness corresponding to an abrasive having a particle size of 61,000 or more, the light dispersion effect is small and it is not effective in suppressing the occurrence of spectral color. Therefore, the uneven surface was rougher than the surface roughness corresponding to #1000 abrasive, which is effective in suppressing the occurrence of spectral color.

[Effect]

Most of the light emitted from the lens is refracted and distributed according to a predetermined refractive index based on the basic spherical surface of the projection lens. Since a portion of the light is dispersed on the surface, the density of the single color light that gathers in one place due to chromatic aberration becomes lower by the amount equivalent to the dispersed light, which prevents the generation of spectral colors on the cutoff line. Further, a portion of the light emitted from the lens is dispersed when the light is emitted from the lens, and the dispersed light is also guided above the cutoff line, so that the too sharp difference in brightness and darkness at the cutoff line is alleviated.

〔Example〕

Next, an embodiment of the present invention will be described based on the drawings.

Figures 1 and 2 show an embodiment of the present invention.
Figure 51 is a longitudinal cross-sectional view of a projector-type automobile headlamp (headlamp for sub-beam formation), and Figure 2 is an enlarged cross-sectional view of the main part of the projection lens used in the headlamp, showing the spectral effect on the lens surface. FIG.

In these figures, reference numeral 10 denotes an elliptical reflector whose inner circumferential surface is a light reflecting surface coated with aluminum, and has an elliptical reflector 1.
A bulb 12 is inserted into a bulb insertion hole 11 formed at the rear top of the mirror 10, and a filament 13 serving as a light source is placed at the first focal point F□ of the elliptical reflecting mirror 10. A shade 14 for forming a cutoff line is arranged near the second focal point F2 of the elliptical reflector 10.
A projection lens 20 made of a convex lens is disposed further in front of the elliptical reflector 10, so that the light reflected by the elliptical reflector 10 is converted into substantially parallel light and distributed in a predetermined direction ahead. It has become. Reference numeral 16 denotes a substantially cylindrical lens holder that supports the projection lens 20 at its front end opening and integrates the elliptical reflection MIO and the projection lens 20 as a projection unit l-30. The outer peripheral surface of the lens holder 16 is painted black, which is effective in making the area around the projection lens 20 a subdued color when the lamp is not lit. The shade 14 is arranged at the focal point of the projection lens 2o, and blocks the light that is below the optical axis from the light that is reflected by the elliptical reflector 10 and goes forward, and produces a clear image that follows the shape of the upper edge of the shade. It is designed to form a cut-off line.

Reference numeral 32 is a lamp body, and the light projection unit 30 is
Inside the lamp body 32, there are a swinging fulcrum (not shown) of the pivot joint structure, a left-right aiming point (not shown) and a vertical aiming point (not shown) arranged orthogonally to the swinging fulcrum when viewed from the front of the lamp. It is supported at three points (not shown).

The horizontal aiming point and the vertical aiming point have a structure in which an aiming screw (not shown) is rotatably supported on the lamp body, and is supported on the back of the lamp body. By rotating the direction aiming screw (direction aiming screw), the light projection unit 30 is tilted around a horizontal axis and a vertical axis (not shown), respectively, to determine the direction in which light is emitted.

In other words, it is possible to adjust the irradiation direction of the headlamp. Reference numeral 34 designates a transparent lamp cover attached to the periphery of the front opening of the lamp body 32. Further, reference numeral 36 denotes a cylindrical lens cover fixed to the back side of the lamp cover 34, and is arranged in a position in front of the projection lens 20 to cover the periphery of the projection lens 20. The side of the lens cover 36 facing the projection lens 2o is painted black.

This prevents unnecessary reflection of light in terms of light distribution, and also makes the entire inside of the lamp appear in a calm color when the lamp is not lit, thereby improving the appearance of the lamp.

The projection lens 2o is made of glass and is located on the light incident surface side (bulb 12
side) is a flat surface, and the light exit surface side is macroscopically spherical (see Figure 1, 9. No. 2, No. 21).
The surface of the spherical shape 21 is processed with minute irregularities, and as shown in FIG.
A finely uneven surface consisting of 3 is formed. These microscopic asperities disperse part of the transmitted light in various directions, thereby alleviating excessive differences in brightness and darkness at the cut-off line, and also eliminating the occurrence of a color spectrum along the cut-off line. As a method for forming this micro-irregular surface, it is sufficient to polish the spherical side of a polished normal projection lens using an abrasive with a grain size of #4oO, and to manufacture a lens with micro-irregularities formed by molding. The lens molding surface of the mold was roughened to correspond to #400 by shot blasting or the like.

The projection lens is formed by molding using a mold having a roughened molding surface. The practical range of minute irregularities for actively dispersing the light emitted from the lens and suppressing the occurrence of color spectrum along the cut-off line is that the abrasive particle size is JIS standard #320 to #10.
It is desirable that the surface roughness be in the range corresponding to 00,
In particular, a surface roughness corresponding to a particle size of around #400 is most preferable.

Next, the direction in which light passes through the projection lens 2o will be explained with reference to FIG.

The light from the filament 13 of the bulb 12, which is the light source, is reflected by the light reflecting surface of the elliptical reflecting mirror 12, and once condensed at the second focal point F7, it is transmitted through the projection lens 20 and is shown in the first same-sex number. The light is refracted and distributed in a predetermined direction ahead. Most of the light emitted from the lens 20 is caused by the basic spherical shape 2 of the lens, as shown in the second homogeneous number.
1 as an interface, the light is emitted in a predetermined direction (a predetermined direction substantially parallel to the optical axis, similar to the conventional example shown in FIG. 3).

However, on an inclined surface different from the spherical shape 21 of the minute unevenness on the lens surface, as shown in the second homogeneity numbers L□ to L4, the emitted light has an interface incident angle θ (θ8, 0) when exiting the lens.
□...). That is, a part of the light emitted from the lens 20 is dispersed as shown in the second homogeneity numbers L to L4. For this reason, most of the emitted light is emitted in the same direction and forms a clear cutoff line, but the symbol L
Part of the light other than the emitted light shown by L4 becomes light that is dispersed in various directions different from the light, and is also guided above the cutoff line, making the cutoff line clear. Avoid doing too much. Also, due to chromatic aberration, the emitted light is split into blue light I2b, green light 12gy, and red light Qr, and nine of each monochromatic light Qb, Qg, and Qr are focused on the optical axis to form a color spectrum above the cutoff line. It works like this. However, the energy of the emitted light is smaller than that of the light incident on the projection lens 2o by the amount equivalent to the dispersed lights L8 to L4, and there is not enough energy to generate a color spectrum along the cut-off line. Furthermore, the outgoing light L~L, which has a different direction from the outgoing light, is split into Qb, Ωg, and Ωr, respectively, due to chromatic aberration, but these monochromatic lights are not focused on the same spot like the outgoing light. , are dispersed in various directions and do not contribute at all to the formation of the color spectrum above the cut-off line. Therefore, the density of light that acts on the formation of a color spectrum on the cutoff line decreases, resulting in a state in which no color spectrum is generated.

Further, the roughness of the projection lens surface is determined by both the optical limit in light distribution and the limit in lens strength. That is,
If the surface roughness is rougher than the unevenness corresponding to #320, there will be more scattered light than emitted light in a predetermined direction, and the cut-off line will become unclear and the amount of light will decrease. Furthermore, when the unevenness is formed by molding, residual strain remains during the forming of the unevenness, resulting in non-uniform refractive index and insufficient lens strength. Therefore, the surface roughness was set to be finer than the unevenness corresponding to #320 as a range in which a sufficient amount of light distribution with a clear cut-off line can be obtained and a range without the influence of residual distortion. On the other hand, if the surface roughness is finer than that corresponding to #1000, the dispersion effect of the emitted light will be small and there will be no effect in suppressing the occurrence of spectral colors. Therefore, the surface roughness was set to be rougher than the surface roughness corresponding to #1000, which is effective in suppressing the occurrence of spectral colors.

The shape of the minute irregularities formed on the lens surface may be the above-mentioned spherical irregularities or satin-like irregularities.In addition, a part of the light emitted from the lens is dispersed to generate a color spectrum along the cut-off line. If the uneven shape is effective in suppressing

It is not limited to these.

〔Effect of the invention〕

As is clear from the above description, in the automobile headlamp according to the present invention, a portion of the light emitted from the projection lens undergoes various changes when emitted from the micro-rugged surface uniformly distributed on the surface of the lens. Since the light is dispersed in the direction, the density of the single color light that gathers in one place due to chromatic aberration becomes lower by the distance where it is dispersed, and the color spectrum along the cut-off line becomes impossible. Further, since a part of the light emitted from the projection lens is dispersed and the dispersed light is guided above the cutoff line, the too sharp difference in brightness and darkness at the cutoff line is alleviated.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of a headlamp according to the present invention, and FIG. FIG. 3 is a schematic diagram showing the light emitting optical system of a conventional projector-type headlamp, FIG. 4 is a diagram showing the light distribution pattern of a conventional projector-type headlamp, and FIG. 1 is a diagram showing a comparison of brightness difference curves at a cut-off line between a parabolic reflector type headlamp and a conventional projector type headlamp. 10... Elliptical reflector, 12... Bulb. 13... Filament as a light source, 14... Shade, 20... Projection lens. 21...Basic spherical shape of lens, 22...Minute recess, 23...Minute convexity, 30...Light projection unit, 32...Lamp body. F: First focus of the elliptical reflector, F2: Second focus of the ellipse reflector, L: Light emitted from the lens in a predetermined direction. L□~L... Dispersed light that is part of the lens output light.

Claims (1)

[Claims] (1) an elliptical reflector, a light source provided near the first focal point of the elliptical reflector, a shade for forming a cutoff line provided near the second focus of the elliptical reflector, and a shade in front of the shade; In a headlamp for an automobile, the headlamp includes a projection lens arranged such that the focal point is a focal position, and converts the light reflected by the elliptical mirror into parallel light and distributes the light in a predetermined direction in front of the vehicle, the side from which the light of the projection lens exits. An automobile headlamp characterized in that a finely uneven surface is formed on the surface of the lens to disperse a portion of light emitted from the lens.