JP2014022038A - Vehicular head lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular head lamp which forms an appropriate light distribution pattern for travelling while the depth in the longitudinal direction of the head lamp is made compact.SOLUTION: A vehicular head lamp 1 comprises: a light source unit 2; a spheroidal first reflection surface 31 arranged ahead of a fluorescent body 22 of the light source unit 2, and reflecting downward the light emitted from the fluorescent body 22; a planar second reflection surface 24 arranged below the first reflection surface 31, and reflecting forward the light reflected by the first reflection surface 31; a projection lens 4 having an optical axis Ax extending in the longitudinal direction, arranged ahead of the second reflection surface 24, and projecting forward the light reflected by the second reflection surface 24. The vehicular head lamp forms a light distribution pattern for travelling in front of a vehicle. The second reflection surface 24 is inclined with respect to the optical axis Ax of the projection lens 4 at an inclination angle θ larger than 45°.

Description

  The present invention relates to a vehicle headlamp.

  2. Description of the Related Art Conventionally, a vehicle headlight such as an automobile headlight that uses a semiconductor light source such as a light emitting diode is known. In this type of vehicle headlamp, there has been proposed one in which the depth in the front-rear direction is made compact by bending the optical path in the lamp at right angles using two reflecting surfaces (reflectors) (for example, Patent Documents 1 and 2).

  Specifically, the vehicular headlamp includes an elliptical reflecting surface for light distribution control disposed in front of the semiconductor light source and a planar surface disposed in the vertical direction (for example, above or below). A reflecting surface and a convex lens-like projection lens disposed in front of the reflecting surface are provided, and the planar reflecting surface is inclined at an inclination angle of 45 ° with respect to the optical axis of the projection lens.

  In this vehicle headlamp, light emitted forward from a semiconductor-type light source is reflected in a substantially vertical direction while being distributed by an elliptical reflecting surface, and then reflected forward by a planar reflecting surface to be projected from a projection lens. Irradiated forward. In this process, a part of the light is blocked or the like, so that a light distribution pattern for passing (so-called low beam) is formed in the front.

JP 2009-259468 A Japanese Patent No. 4458067

  However, when it is intended to form a traveling light distribution pattern (a so-called high beam) instead of the passing light distribution pattern by the conventional vehicle headlamp, the plane reflecting surface is 45 ° with respect to the optical axis of the projection lens. Therefore, as shown in FIG. 5, the light passing through the projection lens is shifted only to the elliptical reflecting surface side (upper side in FIG. 5) from the optical axis. As a result, the chromatic dispersion in the projection lens is biased, and color unevenness due to chromatic aberration occurs in the traveling light distribution pattern, making it impossible to form a suitable traveling light distribution pattern.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the vehicle headlamp which can form the suitable light distribution pattern for driving | running | working, forming the depth of the front-back direction compactly.

In order to solve the above problems, the present invention provides:
A semiconductor light source;
A first reflecting surface of a spheroid system that is disposed in front of the semiconductor-type light source and reflects light emitted from the semiconductor-type light source in a vertical direction substantially perpendicular to the front-rear direction;
A planar second reflecting surface that is disposed in the vertical direction of the first reflecting surface and reflects light reflected by the first reflecting surface forward;
A projection lens having an optical axis along the front-rear direction, disposed in front of the second reflecting surface, and projecting the light reflected by the second reflecting surface to the front;
In a vehicle headlamp that forms a light distribution pattern for traveling ahead,
The second reflecting surface is inclined at an inclination angle larger than 45 ° with respect to the optical axis of the projection lens.

According to the present invention, the light emitted forward from the semiconductor-type light source is reflected in the vertical direction by the first reflecting surface, then further reflected forward by the second reflecting surface and projected forward from the projection lens. The depth in the front-rear direction of the lamp can be made compact by bending the optical path in the lamp at a substantially right angle.
Further, since the second reflecting surface is inclined at an inclination angle larger than 45 ° with respect to the optical axis of the projection lens, the light enters and exits the projection lens as compared with the conventional case where the reflecting surface is inclined at 45 °. Light can be equalized with respect to the optical axis. Therefore, chromatic dispersion generated in the projection lens can be made more uniform as compared with the conventional case, and as a result, a suitable traveling light distribution pattern in which color unevenness is suppressed can be formed.

It is a perspective view of the vehicle headlamp in an embodiment. It is a longitudinal cross-sectional view of the vehicle headlamp in the embodiment. It is a figure for demonstrating the optical path in the vehicle headlamp in embodiment. It is a graph which shows the relationship between the inclination-angle of the 2nd reflective surface in embodiment, and the color difference of the light distribution pattern for driving | running | working. It is a longitudinal cross-sectional view of the conventional vehicle headlamp.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a vehicular headlamp 1 according to the present embodiment, and FIG. 2 is a vertical cross-sectional view (a cross-sectional view orthogonal to the left-right direction) of the vehicular headlamp 1.
In the following description, the terms “front”, “rear”, “left”, “right”, “upper”, and “lower” mean the direction seen from the vehicle headlamp 1 unless otherwise specified. And

  As shown in FIGS. 1 and 2, a vehicle headlamp 1 is mounted on a front portion of a vehicle (not shown) to form a traveling light distribution pattern (so-called high beam) in front of the light source unit 2. The lens holder 3 and the projection lens 4 are provided.

Among these, the light source unit 2 includes a semiconductor laser light source (not shown), an optical fiber 21 that guides light emitted from the semiconductor laser light source, a phosphor 22 provided at the front end (front end) of the optical fiber 21, and the light source. A light source holder 23 for attaching the unit 2 to the rear part of the lens holder 3 is provided. In the light source unit 2, blue light is emitted as excitation light of the phosphor 22 from the semiconductor laser light source, and the blue light excites the phosphor 22 made of, for example, YAG (Y 3 Al 5 O 12: Ce 3 +), thereby causing the phosphor 22 to emit light. As a result of the yellow light being emitted, the blue light and the yellow light are mixed (mixed), and white light is emitted forward from the phosphor 22.
In addition, a planar second reflecting surface 24 is formed on the front surface of the light source holder 23 at a portion located below the phosphor 22. The second reflecting surface 24 will be described later.

The lens holder 3 is formed in a cylindrical shape that opens both front and rear, and supports the projection lens 4 at the peripheral edge of the front opening. In addition, the light source unit 2 is attached to the rear opening of the lens holder 3 so that the phosphor 22 is exposed at the upper part in the rear opening.
On the rear inner surface of the upper wall of the lens holder 3, a first reflection surface 31 for light distribution control that mainly defines the shape of the light distribution pattern for travel is formed in a portion located in front of the phosphor 22 of the light source unit 2. Has been. The first reflecting surface 31 is a free-form surface based on a spheroidal surface having a first focal point F11 located in the vicinity of the phosphor 22 and a second focal point F12 located below the first focal point F11. Yes, the light emitted forward from the phosphor 22 is reflected downward so as to be condensed at the second focal point F12. Strictly speaking, the first reflecting surface 31 is formed so as to reflect light toward a position shifted downward from the second focal point F12 toward the lower portion in order to widen the traveling light distribution pattern in the vertical direction. Yes. Further, the second focal point F12 of the first reflecting surface 31 is a point that is symmetrical with respect to the focal point F2 of the projection lens 4 described later with respect to the second reflecting surface 24, that is, a pseudo focal point of the projection lens 4. is there.

  The above-described second reflecting surface 24 formed on the front surface of the light source holder 23 is exposed at the lower half portion in the rear opening of the lens holder 3. The second reflecting surface 24 is located below the first reflecting surface 31, is in front of the focal point (rear focal point) F <b> 2 of the projection lens 4, and is the second of the focal point F <b> 2 and the first reflecting surface 31. It is located between the focal point F12 and is a plane of symmetry between the focal point F2 of the projection lens 4 and the second focal point F12 of the first reflecting surface 31 as described above. The second reflection surface 24 is inclined at an inclination angle θ of 52.5 ° with respect to the optical axis Ax of the projection lens 4 along the front-rear direction, and light reflected downward by the first reflection surface 31. Is reflected toward the front projection lens 4. However, the inclination angle θ of the second reflecting surface 24 may not be 52.5 ° as long as it is larger than 45 °, as will be described later.

  The projection lens 4 is an acrylic plano-convex lens having a front surface as a convex surface, and a peripheral portion is supported by the lens holder 3 so as to cover the front opening of the lens holder 3. The projection lens 4 is disposed in front of the second reflecting surface 24 and has the optical axis Ax along the front-rear direction and the focal point F2 located behind the second reflecting surface 24 as described above. doing. The projection lens 4 projects the light reflected forward by the second reflecting surface 24 forward. In addition, the projection lens 4 is cut down at both the upper and lower ends that do not affect the light distribution control (no light enters and exits), and is miniaturized.

  In the vehicle headlamp 1 having the above configuration, as shown in FIG. 3, light (white light) emitted forward from the phosphor 22 of the light source unit 2 is second focused by the first reflecting surface 31. After being reflected downward so as to be substantially condensed on F12, it is further reflected forward by the second reflecting surface 24. And this light is projected ahead by the projection lens 4, and the light distribution pattern for driving | running | working is formed ahead.

  At this time, since the second reflection surface 24 is inclined at an inclination angle θ of 52.5 ° with respect to the optical axis Ax of the projection lens 4, the light reflected by the second reflection surface 24 is the optical axis Ax. The light enters and exits the projection lens 4 so that the light amount is substantially equal to the top and bottom. As a result, the chromatic dispersion generated in the projection lens 4 is made substantially uniform above and below the optical axis Ax, and a suitable traveling light distribution pattern in which color unevenness is suppressed is formed. However, if the inclination angle θ of the second reflecting surface 24 is a value larger than 45 °, the color unevenness of the traveling light distribution pattern is suppressed compared to the conventional case where the inclination angle of the reflecting surface is 45 °. can do.

Here, the influence of the inclination angle θ of the second reflecting surface 24 on the color unevenness of the traveling light distribution pattern will be described with reference to FIG. FIG. 4 is a graph showing the relationship between the inclination angle θ of the second reflecting surface 24 and the color difference Cy of the traveling light distribution pattern. The color difference Cy is the largest color difference (chromaticity with reference to white) in the traveling light distribution pattern projected onto the virtual screen.
As shown in this figure, the color difference Cy of the traveling light distribution pattern is the smallest when the inclination angle θ of the second reflecting surface 24 is approximately 52.5 °, regardless of the focal length f of the projection lens 4. That is, color unevenness is most suppressed at this time.

  In addition, the color difference Cy allowed in the light distribution pattern for running is approximately 0.06 in the white chromaticity range according to the European Commission for Europe (ECE) standard, which is supposed to comply with Japanese safety standards. Therefore, it can be considered as ± 0.03 with respect to the center value. Therefore, the inclination angle θ of the second reflecting surface 24 that allows the color difference Cy of the traveling light distribution pattern to be within the allowable range of the above standard is 50 ° to 55 ° when the focal length f = 10 mm, and the focal length f When it is 15 mm, the angle is 47.5 ° to 57.5 °.

  As described above, according to the vehicle headlamp 1, the light emitted forward from the phosphor 22 of the light source unit 2 is reflected downward by the first reflecting surface 31, and then forward by the second reflecting surface 24. Since the light is further reflected and projected forward from the projection lens 4, the depth of the lamp in the front-rear direction can be made compact by bending the optical path in the lamp at a substantially right angle.

  Further, since the second reflection surface 24 is inclined at an inclination angle θ larger than 45 ° with respect to the optical axis Ax of the projection lens 4, the projection lens is compared with the conventional case where the reflection surface is inclined at 45 °. The light that enters and exits 4 can be equalized with respect to the optical axis Ax. Therefore, compared with the prior art, the chromatic dispersion generated in the projection lens 4 can be made more uniform above and below the optical axis Ax, and as a result, a suitable traveling light distribution pattern with suppressed color unevenness can be formed.

  The embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the light source unit 2 including the semiconductor laser light source and the phosphor 22 is described as the light source of the vehicle headlamp 1. However, the semiconductor light source according to the present invention is a semiconductor light emitting device. Any light source that emits white light may be used. For example, a light emitting diode may be used.

  In addition, the optical path is once bent downward by the first reflecting surface 31 and the second reflecting surface 24 and then returned to the original state. However, if the optical path is bent in a vertical direction substantially perpendicular to the front-rear direction, the optical path is not downward. It may be in the upper direction or the left-right direction.

1 Vehicle headlamp 2 Light source unit (semiconductor light source)
DESCRIPTION OF SYMBOLS 21 Optical fiber 22 Phosphor 23 Light source holder 24 2nd reflection surface (theta) Inclination angle 3 Lens holder 31 1st reflection surface F11 1st focus F12 2nd focus 4 Projection lens Ax Optical axis F2 Focus

Claims (3)

A semiconductor light source;
A first reflecting surface of a spheroid system that is disposed in front of the semiconductor-type light source and reflects light emitted from the semiconductor-type light source in a vertical direction substantially perpendicular to the front-rear direction;
A planar second reflecting surface that is disposed in the vertical direction of the first reflecting surface and reflects light reflected by the first reflecting surface forward;
A projection lens having an optical axis along the front-rear direction, disposed in front of the second reflecting surface, and projecting the light reflected by the second reflecting surface to the front;
In a vehicle headlamp that forms a light distribution pattern for traveling ahead,
The vehicle headlamp, wherein the second reflecting surface is inclined at an inclination angle larger than 45 ° with respect to the optical axis of the projection lens.   2. The vehicle headlamp according to claim 1, wherein the inclination angle of the second reflecting surface is within a range of 47.5 ° to 57.5 °.   The vehicle headlamp according to claim 2, wherein the inclination angle of the second reflecting surface is within a range of 50 ° to 55 °.

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