EP2320130A1

EP2320130A1 - Projector type headlight

Info

Publication number: EP2320130A1
Application number: EP10014339A
Authority: EP
Inventors: Tadao Tsukagoshi; Ryoji Konoki; Yuta Takahashi; Hideyasu Shoji
Original assignee: Stanley Electric Co Ltd
Current assignee: Stanley Electric Co Ltd
Priority date: 2009-11-05
Filing date: 2010-11-05
Publication date: 2011-05-11
Anticipated expiration: 2030-11-05
Also published as: JP2011100589A; EP2320130B1; JP4961005B2

Abstract

A projector type headlight includes: a reflector; a light source valve arranged in a vicinity of a rear focal point of the reflector; a shade arranged so that an upper end potion of the shade is placed in a vicinity of a front focal point the reflector; a convex lens arranged in front of the reflector, the light source valve, and the shade; and a groove formed in a front surface of an upper portion of the shade.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a projector type headlight, and particularly to a projector type headlight to be used as a headlight for a vehicle.

Description of Related Art

A projector type headlight to be used as a headlight for a vehicle conventionally includes a reflector, a convex lens, a light source, and a shade (for example, see Japanese Utility Model Application Laid-Open Publication No. Hei6-41003 ). The light source is placed in a vicinity of a focal point of the reflector, and the shade is placed in a vicinity of a focal point of light which is irradiated from the light source and reflected by the reflector. The light irradiated from the light source and the light reflected by a reflecting mirror respectively pass through the lens after lower parts of the lights are blocked by the shade. The shade has a shape which is designed to form a light distribution pattern pursuant to a predetermined standard, for example ECE Regulations.
When using the above-described shade, an illumination intensity at a predetermined point (for example, B50L or B50R in the ECE Regulations) in the light distribution pattern may exceed an acceptable range (up to 0.5 [1x]).

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a projector type headlight by which an illumination intensity at a predetermined point in a light distribution pattern can fall within an acceptable range.
According to a first aspect of the invention, there is provided a projector type headlight including: a reflector; a light source valve arranged in a vicinity of a rear focal point of the reflector; a shade arranged so that an upper end potion of the shade is placed in a vicinity of a front focal point the reflector; a convex lens arranged in front of the reflector, the light source valve, and the shade; and a groove formed in a front surface of an upper portion of the shade.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, advantages and features of the present invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention, and wherein:

FIG. 1 is a front view showing a whole configuration of a projector type headlight according to the present embodiment;
FIG. 2 is an exploded perspective view showing a skeleton framework of the projector type headlight of Fig. 1;
FIG. 3 is a cross-section view schematically showing a cross-section shape viewed from cutting-plane line III-III in Fig. 1;
FIG. 4 is a front view showing a whole configuration of a shade provided in the projector type headlight of Fig. 1;
FIG. 5 is a top view showing the whole configuration of the shade of Fig. 4;
FIG. 6 is an enlarged view where a portion in a vicinity of a groove provided in the shade of Fig. 4 is enlarged;
FIG. 7 is a cross-section view showing a cross-section shape of Fig. 6 viewed from a cutting-plane line VII-VII;
FIG. 8 is a cross-section view showing a cross-section shape of a shade as a comparative example;
FIG. 9 is a cross-section view showing a variation of the groove provided in the shade; and
FIG. 10 is an enlarged view showing the variation of the groove provided in the shade.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, a headlight for a vehicle according to the present invention will be described. FIG. 1 is a front view showing a whole configuration of a projector type headlight according to the present embodiment, FIG. 2 is an exploded perspective view showing a skeleton framework of the projector type headlight, and FIG. 3 is a cross-section view schematically showing a cross-section shape viewed from cutting-plane line III-III in Fig. 1
As shown in Figs. 1-3, a projector type headlight 1 is provided with a reflector 2, a light source valve 3, a convex lens 4, a holder 5, and a shade 6.
The reflector 2 is composed of an upper reflector 21, a rear reflector 22, and a lower reflector 23. A reflection surface which is constituted by the upper reflector 21, the rear reflector 22, and the lower reflector 23, is optically designed based on a free-form surface on the basis of paraboloid of revolution. In Fig. 3, a front focal point of a reflection surface 24 of the reflector 2 is denoted by reference number F1, and a rear focal point thereof is denoted by reference number F2.
The light source valve 3 is fixed to the rear reflector 22, and arranged so that a filament of the light source valve 3 is placed in a vicinity of the rear focal point F2 of the reflector 2.
The convex lens 4 is a plano-convex lens, and arranged so that a convex surface thereof faces forward. The convex lens 4 is also arranged at the position where the rear focal point of the convex lens 4 overlaps the front focal point F1 of the reflector 2.
The holder 5 includes a supporting section 51 which supports the reflector 2, shade 6, and convex lens 4, and an engagement section 52 which makes the convex lens 4 be engaged with respect to the supporting section 51.
The supporting section 51 has a substantially tubular shape, and the convex lens 4 engages with a forward end portion of the supporting section 51. In both side portions of the supporting section 51, screw holes 511 into which screws 53 for fixing the engagement section 52 are inserted are formed respectively. Also a plurality of through-holes 512 for fixing the shade 6 and reflector 2 are formed respectively in the both side portions of the supporting section 51.
The shade 6 is arranged so that an upper end portion thereof is placed in a vicinity of the front focal point F1 of the reflector 2. The shade 6 will be hereinafter described in detail. FIG. 4 is a front view showing a whole configuration of the shade 6, and FIG. 5 is a top view showing the whole configuration of the shade 6.
As shown in Figs. 4 and 5, the shade 6 includes a body section 61 which defines a cut-off region, and attachment sections 62 which laterally extend from both side portions of the body section 61 respectively.
The body section 61 includes a base portion 611 which has a substantially semicircular shape when viewed from the above, and a wall portion 612 provided to stand upward from an arcuate portion of the base portion 611.
In a front-end central portion of the base portion 611, a cutout 613 is formed in a backward direction. On a top surface of the base portion 611, a number of recess portions 614 extending along in a front-back direction are formed.
The wall portion 612 is curved to have a substantially arcuate shape when viewed from the above, a convex portion of which faces rearward. A part of an upper portion of the wall portion 612 has a larger thickness than other portions thereof. On a front surface of this thicker portion 615, a groove 616 is formed along a horizontal direction. On a front surface of the wall portion 612, a number of recess portions 617 extending along a vertical direction are formed.
FIG. 6 is an enlarged view where a portion in a vicinity of the groove 616 is enlarged, and FIG. 7 is a cross-section view showing a cross-section shape of the shade 6 of Fig. 6 viewed from a cutting-plane line VII-VII. As shown in Figs. 6 and 7, the groove 616 extends along the horizontal direction, and is recessed rearward so as to have a U-shaped cross-section. Concretely, each of an upper corner portion 616a and a lower corner portion 616b has a concave curved surface.
A length, width, depth, and installation position of the groove 616 are respectively determined based on various experiments, simulations, and the like, so that an illumination intensity at point of B50L or B50R falls within an acceptable range (up to 0.5 [1x]). A size and an installation position of the thicker portion 615 are determined correspondingly to the length, width, depth, and installation position of the groove 616.
As shown in Fig. 4, through-holes 621 are respectively formed in the attachment sections 62. Into the through-holes 621, fixing screws (not-shown) are respectively inserted through the through holes 512 of the supporting section 51. By making the fixing screws engage with the rear reflector 22 through the through- holes 512 and 621, the rear reflector 22, the supporting section 51, and the shade 6 are mounted.
Next, an operation of a projector type headlight 1 will be described.
When the light source valve 3 is turned on, a part of irradiated light travels forward directly, and other lights are reflected by the reflection surface 24 of the reflector 2 and travel forward indirectly. The parts of the lights traveling forward are cut off by the wall portion 612 of the shade 6. On the other hand, the lights passing above the wall portion 612 of the shade 6 pass through the convex lens 4 so that a region in front of the vehicle is irradiated with these lights. At this time, a part of the lights passing above the wall portion 612 of the shade 6 is reflected by the convex lens 4 (see Arrow L1 shown in Fig. 3). Then, the lights reflected by the convex lens 4 are collected at the rear focal point of the lens 4, namely the front focal point F1 of the reflector 2.
For example, in the case of a shade 6A not including a groove as shown in Fig. 8, because an upper end portion of a wall portion 612a thereof is flat, the light reflected by the convex lens 4 is total-reflected by the upper end portion of the wall portion 612a and travels forward (see Arrow L2 shown in Fig. 8). When the point of B50L or B50R is irradiated with the light total-reflected by the wall portion 612a, an illumination intensity of this point would exceed the acceptable range.
By contrast, according to the shade 6 of the present embodiment, because the groove 616 is formed in the front surface of the upper end portion of the wall portion 612, the lights traveling toward the front focal point F1 are diffusely reflected in the groove 616 to be scattered about (see Arrows L3 shown in Fig. 7). By this, the lights traveling toward the point of B50L or B50R can be reduced.
As described above, according to the projector type headlight 1 of the present embodiment, because the groove 616 is formed in the front surface of the upper end portion of the shade 6, the lights reflected by the groove 616 in the front surface of the shade 6 can be scattered about. By this, the lights which are reflected by the front surface of the shade 6 and reach the point of B50L or B50R are reduced. As a result, the illumination intensity at this point can fall within the acceptable range.
Moreover, because the groove 616 formed in the front surface of the upper end portion of the shade 6 extends in the horizontal direction, it becomes possible to make the light be scattered across a predetermined width in the horizontal direction. In other words, the lights traveling toward the point of B50L or B50R can be scattered about with one groove.
Furthermore, because the groove 616 is formed in the thicker portion 615, a depth of the groove 616 can be made as large as possible so that the scattering effect is improved.
Incidentally, it is needless to say that the present invention is not limited to the abovementioned embodiment, and can be changed appropriately.
For example, as shown in Fig. 9, it is preferable that an upper portion of a groove 616b of a shade 6B has a concave curved surface 620b or an inclined surface 621b (denoted by a dotted line in Fig. 9). When the upper portion of the groove 616b has the surface 620b or the surface 621b which slopes down toward the rear thereof in this way, the lights go into the groove 616b are easily reflected downward by the surface 620b or the surface 621b. Consequently, the lights reflected downward by the surface 620b or the surface 621b do not reach the point of B50L or B50R naturally, and thereby the illumination intensity at this point can be reduced.
Although an example where the groove 616 has a shape along the horizontal direction is described in the present embodiment, the shape of the groove is not limited to the above as long as the lights can be reflected by the front surface of the upper end portion of the shade 6. For example, as a shade 6C shown in Fig. 10, it is possible to allow a recess portion 617c formed along the vertical direction to extend to the upper end portion of a thicker portion 615c of a wall portion 612c so that the lights are scattered about.
According to the present embodiment, there is provided a projector type headlight including: a reflector; a light source valve arranged in a vicinity of a rear focal point of the reflector; a shade arranged so that an upper end potion of the shade is placed in a vicinity of a front focal point the reflector; a convex lens arranged in front of the reflector, the light source valve, and the shade; and a groove formed in a front surface of an upper portion of the shade.
Preferably, the groove is formed so as to extend along a horizontal direction.
Preferably, an upper portion of the groove has a surface sloping down rearward.
The inventors of the present invention found out by various experiments and the like that the illumination intensity at the point of B50L or B50R (different depending on whether the headlight is used for right-hand traffic or for left-hand traffic) may exceed an allowable range because the lights reflected inside the projector type headlight are further reflected by the front surface of the shade to pass through the lens. In view of such problem, by forming the groove in the front surface of the upper end portion of the shade as recited in claim 1, the present invention makes the lights reflected by the front surface of the shade be scattered about by the groove. By this, the lights reflected by the front surface of the shade become hard to arrive the point of B50L or B50R. Consequently, the illumination intensity at this point can fall within an acceptable range.
Moreover, because the groove in the upper end portion of the front surface of the shade extends along the horizontal direction, it becomes possible to make the light be scattered across a predetermined width in the horizontal direction. In other words, by one groove, the lights to reach the point of B50L or B50R can be scattered about.
Furthermore, because the upper portion of the groove has the surface sloping down rearward, the lights going into the groove are easily reflected downward. Because the point of B50L or B50R is located at a position higher than a horizontal plane, the lights reflected by the surface downward do not reach the point of B50L or B50R naturally. In other words, since the upper portion of the groove has the surface sloping down rearward, it becomes possible to further reduce the illumination intensity at the point of B50L or B50R.
Although various exemplary embodiments have been shown and described, the invention is not limited to the embodiments shown. Therefore, the scope of the invention is intended to be limited solely by the scope of the claims that follow.

Claims

A projector type headlight comprising:
a reflector;

a light source valve arranged in a vicinity of a rear focal point of the reflector;

a shade arranged so that an upper end potion of the shade is placed in a vicinity of a front focal point the reflector;

a convex lens arranged in front of the reflector, the light source valve, and the shade; and

a groove formed in a front surface of an upper portion of the shade.
The projector type headlight according to claim 1, wherein the groove is formed so as to extend along a horizontal direction.
The projector type headlight according to claim 2, wherein an upper portion of the groove has a surface sloping down rearward.