JP2541869B2 - Automotive headlights - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has two lenses arranged on the optical axis of a bulb,
The present invention relates to a vehicle headlamp having a function of varying a relative distance between the two lenses and diffusing or converging an irradiation light beam.

[Conventional technology]

Conventionally, in a headlight of an automobile, as shown in FIGS. 6 (a) and 6 (b), a cylindrical step 62, 63 having the same pitch is provided in front of the parabolic reflector surface or on the front optical axis of the projector lamp. A lighting device is used in which two lenses 60 and 61 provided with a large number of lenses are directly opposed to each other, and the distance between them is adjusted to make the irradiation range in the left-right direction variable stepwise or in conjunction with vehicle speed or the like. .

[Problems to be Solved by the Invention]

However, in this type of illumination device having the above configuration, (a) the chromatic aberration is larger than that of a single lens, because the direction of the light flux is controlled by the two lenses 60 and 61.

(B) The light flux incident on the periphery of the lens is composed of two lenses.
Since the direction of the luminous flux is largely changed by 60 and 61, the chromatic aberration becomes particularly large, and therefore, as shown in FIG. 6, particularly toward the side peripheral portions (arrows A and B) of the entire luminous flux. Color unevenness occurs in the light flux due to chromatic aberration of the lens. (1) When the light is narrowly diffused (arrow A), the peripheral portion has a slightly reddish irradiation light color.

(2) At the time of wide diffusion (arrow B), the peripheral part has a slightly bluish irradiation color, and therefore, when the peripheral luminous flux is irradiated on the road surface or the guardrail, physiologically uncomfortable feeling occurs. Had.

Also, if the shape of the cylindrical lens step of the two lenses 60 and 61 is made the same in each lens along with the focal length, a flat light distribution is formed, so the illuminance toward the side is also high, and particularly wide diffusion. However, there is a problem in that the road shoulders, guardrails, etc. are too bright and the visibility in front is impaired.

Furthermore, the left and right illumination range of the irradiation pattern is clearly defined regardless of the distance between the two lenses 60 and 61, and if it exceeds this illumination range, it will be abruptly dark, which may cause anxiety in driving a car. There was also.

The present invention was created in view of the above problems,
It is an object of the present invention to provide a vehicle headlamp that eliminates color unevenness of an irradiation light beam due to chromatic aberration of a lens and reduces the contrast of a boundary between a light irradiation area and a non-irradiation area.

[Means for solving the problem]

In order to achieve the above-mentioned object, an automobile headlamp according to the present invention comprises two cylindrical lens steps arranged at the same pitch on the front optical axis of a parallel luminous flux irradiating means for radiating a luminous flux substantially parallel to the optical axis. In an automobile headlight in which lenses are arranged at positions where pitches are opposed to each other and a beam divergence range in the left-right direction can be controlled by adjusting a distance between the lenses, one or both of the lenses are provided. The gist of the lens is that the focal length of each of the cylindrical lens steps is gradually or gradually changed so as to become longer from the optical axis toward the periphery.

[Action]

According to the above configuration, since the focal lengths of the adjacent cylindrical lens steps formed by the outer lens and the inner lens provided on the optical axis are changed, the transmitted light beams of the lenses overlap each other, and the color due to the chromatic aberration of the lens is caused. The unevenness is less noticeable, and the visual recognition control can be improved.

Further, according to the present invention, since the illuminance near the optical axis of the pattern of the irradiation light flux is always the maximum illuminance, the distant visibility is excellent, and the illuminance of the light flux can be appropriately designed and controlled toward the side. Therefore, glare can be suppressed and good visibility can be obtained.

〔Example〕

An embodiment of a vehicle headlamp according to the present invention will be described below with reference to the drawings.

1 and 2 show the first embodiment, in which each of the cylindrical convex lens steps 11a, 11b ... Of the outer lens 1 arranged on the optical axis L has the same focal length and the same cross section. Each of the cylindrical convex lens steps 21a, 21 of the inner lens 2 is configured to have a shape.
b ... is its focal length f1, as it goes from the optical axis to the periphery.
It has a structure in which f2 and f3 are gradually changed (f1 <f2 <f3) so that they become longer.

As shown in FIG. 2, the light distribution on the screen in the case of the above-mentioned configuration of both lenses 1 and 2 is the light distribution part P1, 21b and 1 by 21a and 11a from the center side by the light flux transmitted through each lens step.
A light distribution part P2 by 1b and a light distribution part P3 by 21c and 11c is formed. Therefore, since the light distributions P1, P2, P3 of the respective portions of the irradiation light flux are superimposed on the other light distributions, the amount of color unevenness of the respective light distributions P1, P2, P3 is reduced and the two light distributions of the same shape are formed. Color unevenness is significantly reduced compared to the case of the lens step.

FIGS. 3 and 4 show a second embodiment of the present invention, in which the cylindrical lens step of the outer lens 1 is constituted by a concave lens step.

Each of the cylindrical concave lens steps of the outer lens 1 arranged on the optical axis L is located on both outer sides of the steps 12a, 12a in the central A zone near the optical axis L and the A zone distant from the optical axis L. It consists of two types of zone steps 12b, 12b ... Cylindrical concave lens step 12 of both zones
The focal lengths fa and fb of a and 12b are configured so that those in the A zone are shorter than those in the B zone (fa <fb). The lens step of the inner lens 2 is formed by a convex lens step, and is divided into an A zone and a B zone so as to correspond to each lens step of the outer lens 1. Then, the steps 22a, 22a of the A zone and the steps 22b, 22b of the B zone located on both outsides of the A zone away from the optical axis L have focal lengths of the A zone more than those of the B zone. It has a short (fa <fb) structure.

In the case of the above-mentioned configuration of both lenses 1 and 2, as shown in FIG. 4, the light distribution on the screen is different in the diffusion angle of the light flux transmitted through each lens step between the A zone and the B zone. The light distributions of the two zones Pa and Pb are overlapped, and the amount of color unevenness of the light distribution is reduced,
Color unevenness is greatly reduced as in the first embodiment, as compared with the case of two lens steps having the same shape.

Incidentally, FIGS. 1 and 3 showing the first and second embodiments show the lens positions of narrow diffusion, and in order to obtain wide diffusion, both lenses 1, 2 are used in the first embodiment. Narrow the space between
In the case of the second embodiment, the distance between both lenses 1 and 2 is expanded. However, in the case of the second embodiment, the maximum illuminance is obtained in the middle because the relative displacement between the two lenses is 1 and 2 depending on how the focal length is taken and how each zone is divided. There is a case. In general, also in the second embodiment, the cylindrical lens step of the outer lens 1 is composed of a convex cylindrical lens,
It is preferable that the irradiation light flux is narrowly diffused when the lenses 1 and 2 are separated from each other, and is wide diffused when the lenses 1 and 2 are close to each other.

Next, FIG. 5 shows an embodiment of a lens driving device for relatively moving the inner lens 2 in the optical axis L direction with respect to the outer lens 1 of the above embodiment.

The leg portion of the front lens 33 forming the outer lens 1 is fitted and fastened to the rectangular opening formed on the front surface of the casing 31, and the inner surface of the opening portion of the casing 31 has substantially the same shape as the leg portion of the outer lens 1. A second frame 34 made of a rectangular tubular body is fixed. Further, a cylindrical first frame 35 is slidably inserted in the second frame 34 in the optical axis L direction, and the inner lens 2 is fixedly mounted on the first frame 35. As described in the first or second embodiment, each of the inner lens 2 and the outer lens 1 has cylindrical convex or concave lens steps 11 and 21 arranged in parallel in a row at equal pitches. Reference numeral 37 is a reflector formed on the optical axis rear side of the inner lens 2, and is a parabolic reflecting mirror surface of the reflector 37.
A valve socket 40 is fixed to the rear end of the casing 31 so that the filament of the bulb 39 for lighting is located at the focal point of 38. Reference numeral 41 denotes a lens drive pipe projecting from the rear end of the first frame 35 in parallel with the optical axis L. The lens drive pipe 41 rotates on the casing 31 with respect to a nut 42 fixedly provided at the end of the lens drive pipe 41. While screwing a freely screwed screw shaft 43, a worm pinion 44 axially attached to the screw shaft 43 is meshed with a worm 45 of a rotation transmission reduction mechanism, and a spur gear 46 axially attached to the form 45 is further engaged. The pinion gear 48 is attached to the drive shaft of the control motor 47 and meshes with the pinion gear 48. Reference numeral 49 is a potentiometer for detecting a mirror transition angle by meshing a spur gear 51 axially attached to the input shaft 50 with a pinion gear 52 axially attached to the worm 45.

When the control motor 47 is driven in the normal rotation or the reverse rotation, the screw shaft 43 is rotated at a predetermined speed via the rotation transmission reduction mechanism, and by the screwing action of the nut 42 screwed with the screw shaft 43. The lens drive pipe 41 is displaced in the arrow X direction. Due to this displacement, the first frame 35 slides on the inner surface of the second frame 34 in the optical axis L direction, and the inner lens 2 changes the relative position in the pitch direction between the cylindrical lens steps 11 and 21 with respect to the outer lens 1. Accurate displacement without both lenses 1,
You can change the relative distance between the two. Then, this relative distance is detected by the potentiometer 49, by presetting the relationship between the relative distance between the two lenses 2 and 6 and the potentiometer 49, the central control circuit for the control motor 47 with the position signal from the potentiometer 17 (Fig. It can be controlled and driven by (not shown), and the diffusion width of the irradiation light beam can be switched.

〔The invention's effect〕

Since the vehicle headlamp according to the present invention is configured as described above, by changing the focal lengths of the adjacent cylindrical lens steps formed by the outer lens and the inner lens provided on the optical axis, Since the transmitted light fluxes of the lenses overlap each other, the color unevenness due to the chromatic aberration of the lenses becomes inconspicuous.

Further, according to the present invention, since the illuminance near the optical axis of the pattern of the irradiation light flux is always the maximum illuminance, the distant visibility is excellent, and the illuminance of the light flux can be appropriately designed and controlled toward the side. Therefore, the guard rail and the road shoulder do not shine more than necessary, and the characteristic is that glare can be suppressed and good visibility can be obtained, and the effect of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is an explanatory view of a lens system showing a first embodiment of a vehicle headlamp according to the present invention, FIG. 2 is an explanatory view of an irradiation pattern by the lens system, and FIG. 3 is a second view of the present invention. 4 is an explanatory view of a lens system showing an embodiment of the present invention, FIG. 4 is an explanatory view of an irradiation pattern by the same lens system, and FIG. 5 shows an embodiment of a drive system of a lens system of a vehicle headlamp according to the present invention. (A) is a partially cutaway side sectional view, (b) is the same plane sectional view, (c) is a rear view, FIG. 6 shows a conventional lens system, and (a) is Explanatory drawing at the time of narrow diffusion, (b) is explanatory drawing at the time of wide diffusion, FIG. 7 is explanatory drawing which shows the irradiation pattern by the same lens system. 1 …… Outer lens, 2 …… Inner lens 11,11a, 11b …… Cylindrical convex lens step 21,21a, 21b …… Cylindrical convex lens step 34 …… Second frame, 35 …… First frame 37 …… Reflector, 38 …… Parabolic reflector surface 39 …… Lighting valve, 41 …… Lens drive pipe 42 …… Nut, 43 …… Screw shaft 44 …… Worm pinion 45 …… Worm, 47 …… Control motor 49 …… Potentiometer

Claims (1)

(57) [Claims] 1. Two lenses having cylindrical lens steps arranged at the same pitch on the front optical axis of a parallel light beam irradiating means for irradiating a light beam substantially parallel to the optical axis are arranged at positions where the respective pitches are opposed to each other. In a vehicle headlamp capable of controlling the beam divergence range in the left-right direction by adjusting the distance between both lenses, the focal length of each of the cylindrical lens steps is adjusted for one or both of the lenses. A vehicle headlight characterized by gradually changing or gradually changing so that it becomes longer from the optical axis toward the periphery.