JP5571532B2 - Vehicle headlamp - Google Patents

Description

  The present invention relates to a vehicle headlamp.

  2. Description of the Related Art Conventionally, as a vehicle headlamp such as an automobile headlight, a combination of a semiconductor light emitting element and a phosphor is known as described in Patent Document 1, for example. The vehicle headlamp described in Patent Document 1 forms a predetermined light distribution pattern by reflecting visible light emitted from a phosphor upon receiving excitation light from a semiconductor light emitting element to the front by a reflecting mirror. Yes.

Japanese Patent No. 4047266

However, in the vehicle headlamp described in Patent Document 1, the light emission mode of the phosphor and the reflection mode of the reflecting mirror are constant, so that only a single light distribution pattern can be formed.
In this respect, it is also conceivable that a plurality of phosphors can be switched to form a plurality of light distribution patterns like a so-called color wheel. However, in such a configuration, it is necessary to shield between the plurality of phosphors so that unintended light does not leak between the plurality of phosphors. There is a risk of thermal deformation due to the light. For this reason, it is desirable that the light from the semiconductor light emitting element is always irradiated to the phosphor without being blocked.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the vehicle headlamp which can form a some light distribution pattern, without light-blocking the light from a semiconductor light-emitting device.

In order to solve the above-mentioned problem, the invention described in claim 1
A semiconductor light emitting device;
A plurality of phosphors that receive the excitation light emitted from the semiconductor light emitting element and emit visible light;
A projection lens that projects the visible light emitted from the plurality of phosphors forward of the vehicle;
In a vehicle headlamp comprising:
The plurality of phosphors are arranged along the circumferential direction on a circumferential surface of a rotating member that is positioned on the optical axis of the projection lens and that is rotatable about a rotating shaft that is orthogonal to the optical axis. The external shape seen from each is formed differently,
The semiconductor light emitting element irradiates one of the plurality of phosphors facing the rear surface of the projection lens with the excitation light.

The invention according to claim 2 is the vehicle headlamp according to claim 1,
The plurality of phosphors are such that the excitation light from the semiconductor light emitting element has a sharper angle as the surface portion is projected onto a higher illuminance portion of the light distribution pattern formed by the visible light from the phosphor. The surface is formed in a concavo-convex shape so as to be incident on the surface.

The invention according to claim 3 is the vehicle headlamp according to claim 1 or 2,
The semiconductor light emitting device is a laser diode.

Invention of Claim 4 is the vehicle headlamp as described in any one of Claims 1-3,
The phosphor includes a diffusing material.

  According to the first aspect of the present invention, excitation light is emitted from the semiconductor light emitting element toward one phosphor facing the rear surface of the projection lens among the plurality of phosphors, and visible light is emitted from the one phosphor. The light is emitted and projected forward of the vehicle by the projection lens. At this time, the plurality of phosphors are arranged along the circumferential direction on the peripheral surface of the rotating member that is positioned on the optical axis of the projection lens and that can rotate around the rotating shaft orthogonal to the optical axis. Since the external shapes seen from the front are different from each other, by rotating the rotating member, the phosphor facing the rear surface of the projection lens can be switched to one having a different external shape. The projected light emission shape can be changed. Therefore, a plurality of light distribution patterns can be formed by merely rotating the rotating member without blocking light from the semiconductor light emitting element.

  According to the second aspect of the present invention, the plurality of phosphors are arranged such that the surface portion projected onto the portion having a higher illuminance in the light distribution pattern formed by the visible light from the phosphor, the semiconductor light emitting element Since the surface is formed in a concavo-convex shape so that the excitation light from is incident at an acute angle, a light distribution pattern having an illuminance distribution according to the surface shape of the phosphor is formed. Therefore, a light distribution pattern having a desired illuminance distribution can be formed only by appropriately forming the surface of the phosphor.

It is a top view of the vehicle headlamp in an embodiment. It is a side view of the vehicle headlamp in an embodiment. It is (a) A arrow directional view of FIG. 2, (b) B arrow directional view, (c) C arrow directional view, (d) D arrow directional view. 3A is a cross-sectional view taken along line PO, FIG. 3B is a cross-sectional view taken along line QO, FIG. 3C is a cross-sectional view taken along line RO, and FIG. 3D is a cross-sectional view taken along line SO. It is a figure for demonstrating the density of the light radiate | emitted from the surface of fluorescent substance. It is the figure which looked at each light distribution pattern which the vehicle headlamp in embodiment forms from the vehicle side. It is the figure which looked at each light distribution pattern which the vehicle headlamp in embodiment forms from the upper direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view of a vehicular headlamp 1 according to an embodiment of the present invention, and FIG. 2 is a side view of the vehicular headlamp 1.
As shown in these drawings, the vehicle headlamp 1 includes a laser diode (hereinafter referred to as LD) 2, a light emitting member 3, and a projection lens 4.

  Among these, the LD 2 is a semiconductor light emitting element according to the present invention, and emits blue laser light toward the light emitting member 3 obliquely rearward to the right. More specifically, the LD 2 emits blue light toward one phosphor 31 facing the rear surface of the projection lens 4 among a plurality of phosphors 31, which will be described later, arranged on the peripheral surface of the light emitting member 3. .

The light emitting member 3 includes, for example, a columnar rotating member 30 extending in the left-right direction. The rotation member 30 is connected to an actuator (not shown) capable of controlling the rotation angle at an end, and is rotatable about a rotation axis along the left-right direction. The shape of the rotating member 30 is not particularly limited as long as it can rotate.
On the circumferential surface of the rotating member 30, four phosphors 31 are arranged at a central angle of 90 degrees along the circumferential direction of the rotating member 30. The phosphors 31 are formed of a fluorescent material that emits yellow light when excited by receiving blue light emitted from the LD 2. For this reason, when the phosphor 31 receives blue light, the blue light scattered by the phosphor 31 is mixed with yellow light, so that white light is emitted radially. Here, since the phosphor 31 substantially functions as a light emitting surface (pseudo light source), the phosphor 31 may be applied only to the surface thereof. Various fluorescent materials such as rare earth-added YAG (Yttrium Aluminum Garnet) can be used as the fluorescent material forming the phosphor 31.

3A to 3D are views taken along arrows A to D in FIG. 2, and FIGS. 4A to 4D are cross-sectional views taken along lines PO and SO in FIG. is there. However, FIGS. 3A to 3D are views of the light emitting member 3 viewed from the front in a state where the phosphor 31 viewed from the front in each of the drawings is directed forward.
As shown in FIGS. 3A to 3D, the four phosphors 31,... Are the first phosphor 31A to the fourth phosphor 31D having different shapes. The first phosphor 31A to the fourth phosphor 31D are formed so as to have different outer shapes in front view as viewed from the outer diameter direction of the rotating member 30, and each outer shape has a light distribution formed by each. The outline of the pattern. Specifically, the outer shape of the first phosphor 31A is the outer shape of the passing beam, the outer shape of the second phosphor 31B is the outer shape of the traveling beam, and the outer shape of the third phosphor 31C is for high-speed traveling. The outer shape of the beam is the outer shape of the fourth phosphor 31D.

  Further, the first phosphor 31A to the fourth phosphor 31D are formed with an uneven surface as shown in FIGS. 4 (a) to 4 (d). The unevenness on the surface determines the illuminance distribution of the light distribution pattern formed by the white light from each phosphor 31. As shown in FIG. 5, in the phosphor 31, the portion where the blue light Lb from the LD 2 is incident at an acute angle with respect to the surface of the phosphor 31 emits the white light Lw at a higher density. It utilizes the fact that it emits light with high brightness. Therefore, the surface portions of the first phosphor 31A to the fourth phosphor 31D are projected from the LD2 as the surface portion projected onto the portion with higher illuminance in the light distribution pattern formed by the white light from each phosphor 31. Are formed in a concavo-convex surface so that the blue light is incident at an acute angle. Specifically, the surface of the first phosphor 31A corresponds to the illuminance distribution of the passing beam, the surface of the second phosphor 31B corresponds to the illuminance distribution of the traveling beam, and the surface of the third phosphor 31C is for high-speed traveling. Corresponding to the illuminance distribution of the beam, each surface is formed in an uneven surface so that the surface of the fourth phosphor 31D corresponds to the illuminance distribution of the urban traveling beam.

  The projection lens 4 is, for example, a plano-convex lens having a convex front surface, and is disposed in front of the light emitting member 3 so that the light emitting member 3 (the rotating member 30) is positioned on the optical axis Ax along the front-rear direction. . The projection lens 4 has an object-side focal point located in the vicinity of the phosphor 31 facing the rear surface thereof, and in front of the vehicle while inverting white light emitted forward from the phosphor 31 vertically and horizontally. Project to.

FIGS. 6A to 6D are views of each light distribution pattern formed by the vehicle headlamp 1 as viewed from the vehicle side, and FIGS. 7A to 7D illustrate the respective light distributions. It is the figure which looked at the pattern from the upper part.
In the vehicle headlamp 1, the blue light (excitation light) emitted from the LD 2 is applied to the phosphor 31 facing the rear surface of the projection lens 4, and is converted into white light by the phosphor 31 and emitted forward. Thereafter, the projection lens 4 projects the image forward and backward while being reversed vertically and horizontally.

At this time, when the first phosphor 31A faces the rear surface of the projection lens 4, the outer shape of the first phosphor 31A is inverted and the first phosphor 31A corresponds to the unevenness of the surface. By emitting light with a luminance distribution, as shown in FIGS. 6 (a) and 7 (a), the outer shape of the first phosphor 31A is turned upside down and left and right, and the unevenness of the surface of the first phosphor 31A. A passing beam Pa having an illuminance distribution in accordance with is formed in front of the vehicle.
In addition, when the light emitting member 3 is rotated from this state and the second phosphor 31B is opposed to the rear surface of the projection lens 4, the outer shape of the second phosphor 31B is inverted and projected. When the body 31B emits light with a luminance distribution according to the unevenness of the surface, as shown in FIGS. 6B and 7B, the outer shape of the second phosphor 31B is inverted vertically and horizontally. A traveling beam Pb having an illuminance distribution corresponding to the unevenness of the surface of the second phosphor 31B is formed in front of the vehicle.
Similarly, when the third phosphor 31C is opposed to the rear surface of the projection lens 4, a high-speed traveling beam Pc shown in FIGS. 6C and 7C is formed, and the fourth phosphor 31D is formed. Is opposed to the rear surface of the projection lens 4, the urban traveling beam Pd shown in FIGS. 6 (d) and 7 (d) is formed.

  According to the above vehicle headlamp 1, the phosphor 31 facing the rear surface of the projection lens 4 can be switched to one having a different outer shape by rotating the light emitting member 3 (rotating member 30). As a result, the light emission shape projected from the projection lens 4 can be changed. Therefore, a plurality of light distribution patterns can be formed by merely rotating the rotation member 30 without blocking the light from the LD 2.

  Further, in the phosphor 31, the blue light from the LD 2 is incident at an acute angle toward the surface portion projected onto the portion with higher illuminance in the light distribution pattern formed by the white light from the phosphor 31. Moreover, since the surface is formed in an uneven surface, a light distribution pattern having an illuminance distribution corresponding to the surface shape of the phosphor 31 is formed. Therefore, a light distribution pattern having a desired illuminance distribution can be formed only by appropriately forming the surface of the phosphor 31.

  It should be noted that the present invention should not be construed as being limited to the above-described embodiment, and of course can be modified or improved as appropriate.

  For example, in the above embodiment, the laser diode (LD2) is used as the semiconductor light emitting element according to the present invention, but a light emitting diode may be used. However, it is preferable to use a laser diode from the point of condensing light to the phosphor 31. Further, the blue light emitted from the LD 2 is preferably collimated with respect to the phosphor 31.

  The phosphor 31 may contain a diffusing material that diffuses the blue light emitted from the LD 2. As the diffusion material, calcium carbonate, titanium oxide, alumina, or the like can be used. In this case, it is preferable from the viewpoint of durability and heat resistance that the fluorescent material and the diffusing material are integrated by sintering rather than using a binder such as a resin.

  In addition, the LD 2 emits blue light and the phosphor 31 emits yellow light by the blue light. However, the present invention is not limited to this, and other configurations that obtain white light (combination of excitation light and fluorescent material) ), Or a configuration capable of obtaining visible light other than white light. For example, each fluorescent material that emits red light and green light may be mixed with excitation light as blue light, or each fluorescent material that emits red light, green light, and blue light as excitation light as ultraviolet light. You may mix. In the latter case, it is better not to include a diffusing material in the phosphor 31 if inconvenience occurs when ultraviolet light leaks.

  In addition, the LD 2 emits blue light obliquely rearward to the right, but may emit blue light from another direction. However, when the emission direction of the blue light is changed, it is needless to say that the uneven shape on the surface of the phosphor 31 needs to be changed as appropriate.

  In addition, the size of the phosphor 31 is preferably as small as possible in order to bring the phosphor 31 close to a point light source, but is preferably a size that does not impair the workability and handling properties.

  In addition, since the luminance of the phosphor 31 changes depending on the density of the fluorescent material and the diffusing material forming the phosphor 31, the illuminance distribution of a desired light distribution pattern can be obtained, for example, by increasing the density near the center. Accordingly, the density distribution of the fluorescent material or the diffusing material may be adjusted.

  Moreover, since the rotation member 30 is also a heat radiating member for releasing heat generated by the Stokes loss of the phosphor 31, it is preferably made of a metal having high thermal conductivity such as copper or aluminum.

1 Vehicle headlamp 2 LD (semiconductor light emitting device)
3 Light emitting member 4 Projection lens 30 Rotating member 31 Phosphor 31A First phosphor 31B Second phosphor 31C Third phosphor 31D Fourth phosphor Ax Optical axis Lb Blue light (excitation light)
Lw White light (visible light)
Pa Passing beam Pb Traveling beam Pc High-speed traveling beam Pd Urban traveling beam

Claims (4)

A semiconductor light emitting device;
A plurality of phosphors that receive the excitation light emitted from the semiconductor light emitting element and emit visible light;
A projection lens that projects the visible light emitted from the plurality of phosphors forward of the vehicle;
In a vehicle headlamp comprising:
The plurality of phosphors are arranged along the circumferential direction on a circumferential surface of a rotating member that is positioned on the optical axis of the projection lens and that is rotatable about a rotating shaft that is orthogonal to the optical axis. The external shape seen from each is formed differently,
The semiconductor light emitting element irradiates one of the plurality of phosphors facing the rear surface of the projection lens with the excitation light.   The plurality of phosphors are such that the excitation light from the semiconductor light emitting element has a sharper angle as the surface portion is projected onto a higher illuminance portion of the light distribution pattern formed by the visible light from the phosphor. The vehicle headlamp according to claim 1, wherein the surface is formed in a concavo-convex shape so as to be incident on the vehicle.   The vehicle headlamp according to claim 1, wherein the semiconductor light emitting element is a laser diode.   The vehicular headlamp according to any one of claims 1 to 3, wherein the phosphor contains a diffusing material.

Images