# Patent

## Title
Vehicle headlight including a plurality of led lighting device units

## Abstract

A headlight has a plurality of lighting device units and a unit support member that supports the plurality of lighting device units. Each lighting device unit has a projection lens, a light emitting diode arranged behind a rear side focus of the projection lens, and a rectilinear propagation blocking member that is arranged in a vicinity of the rear side focus, and blocks a rectilinear propagation of a portion of light emitted from the light emitting diode so as to form a cutoff line. The projection lens and the rectilinear propagation blocking member are integrally formed as a light control member in each light device unit.

## Background
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle headlight to form a predetermined light distribution pattern having a cutoff line at the upper end edge thereof, when light is irradiated by a plurality of lighting device units.
In general, a vehicle headlight can form a light distribution pattern for a low beam having a cutoff line at the upper end edge. Due to the above constitution, while a driver in a vehicle running in the opposite direction is not being given glare, the front visibility in of a driver who drives a vehicle can be ensured as positively as possible.
JP-A-2003-123517 discloses a vehicle headlight that forms a light distribution pattern for a low beam by the irradiation of light sent from a plurality of lighting device units having light emitting elements as the light sources.
When the lighting device of JP-A-2003-123517 is employed, it becomes possible to reduce the thickness of the lighting device. However, in this case, it is necessary to adjust an optical axis of each of the plurality of lighting device units.
On the other hand, when such a constitution that a plurality of lighting device units are supported by a common unit support member is employed, it is possible to simultaneously adjust optical axes of a plurality of lighting device units by tilting the unit support member.
However, the above structure has the following problems. The unit support member attached with a plurality of lighting device units is further attached to a lamp body. Therefore, the lighting device structure becomes complicated.
SUMMARY OF THE INVENTION
The present invention has been accomplished in view of the above circumstances. It is an object of the present invention to provide a vehicle headlight to form a predetermined light distribution pattern having a cutoff line at the upper end portion, when light is irradiated by a plurality of lighting device units, the vehicle headlight characterized in that: the thickness of the lighting device is reduced; and the optical axes of the plurality of lighting device units can be simultaneously adjusted without making the structure of the lighting device complicated.
In the invention of the present patent application, when each lighting device unit is divided into predetermined components and attached to a common unit support member, the above object can be accomplished.
The present invention provides a vehicle headlight to form a predetermined light distribution pattern, at the upper end edge of which a cutoff line is formed, when light is irradiated by a plurality of lighting device units, characterized in that: the plurality of lighting device units are supported by a common unit support member; each lighting device unit has a projection lens, a light emitting element arranged at the rear of the rear side focus of the projection lens and a rectilinear propagation blocking member, which is arranged in the neighborhood of the rear side focus, for blocking a rectilinear propagation of a portion of light emitted from the light emitting element so as to form the cutoff line; the projection lens and the rectilinear propagation blocking member are integrally formed as a light control member; and the light control member and the light emitting element are individually attached to the unit support member.
As long as the light distribution pattern has a cutoff line at the upper end edge, the above “predetermined light distribution pattern” may be a light distribution pattern for a low beam. Alternatively, the above “predetermined light distribution pattern” may be a light distribution pattern composing a portion of the light distribution pattern for a low beam. In the latter light distribution pattern, the light distribution pattern for a low beam can be formed as a compound light distribution pattern in which this light distribution pattern is compounded with a light distribution pattern which is formed by the irradiation of light sent from the lighting device unit except for the above plurality of lighting device units.
The above “light emitting element” means an element-shaped light source having a light emitting portion for emitting light like a substantial spot-shape. The type of the element-shaped light source is not particularly limited. For example, a light emitting diode or a laser diode can be adopted.
Concerning the above “rectilinear propagation blocking member”, as long as it can form a cutoff line and block a rectilinear propagation of a portion of light emitted from the light emitting element, the specific structure of the rectilinear propagation blocking member is not particularly limited. For example, the rectilinear propagation blocking member can be comprised of a light-shielding member or a reflecting member. In this case, “light emitted from the light emitting element” may be direct light sent from the light emitting element. Alternatively, “light emitted from the light emitting element” may be light reflected on the other optical member or light transmitted through the other optical member.
Concerning the above “light control member”, as long as the projection lens and the rectilinear propagation blocking member are integrally formed in it, the light control member maybe a one-body molded product or an insertion molded product. Alternatively, the light control member may be an integrated body in which the projection lens and the rectilinear propagation blocking member are integrated with each other into one body by means of welding (for example, laser welding) or adhesion.
As explained above, in the vehicle headlight of the present invention, a predetermined light distribution pattern having a cutoff line at an upper end edge is formed by the irradiation of light sent from a plurality of lighting device units, the light sources of which are light emitting elements. Therefore, the thickness of the lighting device can be reduced.
In the vehicle headlight of the present invention, a plurality of lighting device units are supported by a common unit support member. Therefore, when this unit support member is tilted, the optical axes of the plurality of lighting device units can be simultaneously adjusted.
In the vehicle headlight of the present invention, the projection lens and the rectilinear propagation blocking member, which compose each lighting device unit, are integrated with each other into one body so that they can be composed as a light control member. Since this light control member and the light emitting element are individually attached to a unit support member, the following operational effects can be provided.
In a lighting device unit composed in such a manner that a portion of light emitted from a light emitting element is prevented from propagating straight by a rectilinear propagation blocking member arranged in the neighborhood of the rear side focus of a projection lens, in order to form a clear cutoff line at a predetermined position with high accuracy, it is very important to ensure the accuracy of the positional relation between the projection lens and the rectilinear propagation blocking member. On the other hand, the accuracy of the positional relation between them and the light emitting element is not so important.
Therefore, as described in the present invention, when the projection lens and the rectilinear propagation blocking member, the accuracy of the positional relation of which must be high, are integrally formed as a light control member and when the light control member and the light emitting element are individually attached to the unit support member, the lighting device unit can be completed without affecting the light distribution performance of the lighting device unit. When the components of the lighting device unit are individually attached to the unit support member, the lighting device structure can be made simple compared with a case in which the completed lighting device unit is attached to the unit support member.
As described above, according to the present invention, in a vehicle headlight composed so that a predetermined light distribution pattern having a cutoff line at an upper end edge can be formed by the irradiation of light sent from a plurality of lighting device units, while the thickness of the lighting device is being reduced, the optical axes of the plurality of lighting device units can be simultaneously adjusted without making the lighting device structure complicated.
When the unit support member is composed of a die-cast product in the above constitution, the following operational effects can be provided.
When the light emitting element of each lighting device unit emits light, heat is generated. However, since each light emitting element is attached to the unit support member composed of a die-cast product, heat generated by each light emitting element can be quickly transmitted to the unit support member, the heat capacity of which is large, by the action of heat conduction. Due to the foregoing, a temperature rise in the light emitting element can be suppressed. Therefore, it is possible to effectively prevent the luminous flux of the light emitting element from being decreased. It is also possible to prevent the color of emitted light from becoming discolored.
When the light control member is composed of an insertion molded product in the above constitution, the following operational effects can be provided.
When the insertion molding is conducted after the projection lens has been inserted, it is possible to integrate the projection lens and the rectilinear propagation blocking member by the insertion molding after the projection lens has been previously formed as a single body. Due to the foregoing, after the profile accuracy of the projection lens has been sufficiently ensured, the accuracy of the positional relation between the projection lens and the rectilinear propagation blocking member can be sufficiently enhanced.
In the above constitution, when each of at least some lighting device units in the plurality of lighting device units includes a reflector for reflecting a beam of light, which is sent from the light emitting element, forward so that the beam of light can be substantially converged upon a neighborhood of the rear side focus of the projection lens, it is possible to enhance a ratio of utilizing the flux of light sent from the light emitting element. In this case, the reflector may be attached to the unit support member separately from the light control member and the light emitting element. Alternatively, the reflector may be attached to the unit support member together with the light control member and the light emitting element.
In this case, when each of the rectilinear propagation blocking members of at least some of lighting device units has a reflecting face, the surface profile of which is predetermined, extending from the neighborhood of the rear side focus of the projection lens to the rear side, the ratio of utilizing the flux of light emitted from the light emitting element can be further enhanced.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view showing a vehicle headlight of an embodiment of the present invention.
FIG. 2 is a sectional view taken on line II-II in FIG. 1.
FIG. 3 is a sectional view taken on line III-III in FIG. 2.
FIG. 4 is an enlarged view showing a primary portion of FIG. 2 in which a lighting device unit for medium diffusion of the vehicle headlight is shown in detail.
FIG. 5 is a sectional side view showing the lighting device unit for medium diffusion in detail.
FIG. 6 is a sectional plan view showing the lighting device unit for medium diffusion in detail.
FIG. 7 is a sectional view taken on line VII-VII in FIG. 4.
FIG. 8 is an exploded perspective view for explaining an attaching structure of attaching the lighting device unit for medium diffusion to a unit support member.
FIG. 9 is a view showing a lighting device unit for condensing light of the vehicle headlight in detail, wherein FIG. 9 is drawn in the same manner as that of FIG. 6.
FIG. 10 is a view showing a lighting device unit for wide diffusion of the vehicle headlight in detail, wherein FIG. 10 is drawn in the same manner as that of FIG. 6.
FIG. 11 is a perspective view showing a light distribution pattern for a low beam formed on a virtual perpendicular screen, which is arranged ahead at a position distant from a lighting device by 25 m, by a beam of light irradiated ahead by the vehicle headlight.
FIGS. 12A to 12C are views showing light distribution patterns composing a portion of the light distribution pattern for a low beam, wherein FIG. 12A is a view showing a light distribution pattern formed by the irradiation of light sent from the lighting device unit for medium diffusion, FIG. 12B is a view showing a light distribution pattern formed by the irradiation of light sent from the lighting device unit for condensing light and FIG. 12C is a view showing a light distribution pattern formed by the irradiation of light sent from the above lighting device unit for wide diffusion.



DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, an embodiment of the present invention will be explained below.
FIG. 1 is a front view showing a vehicle headlight of an embodiment of the present invention. FIG. 2 is a sectional view taken on line II-II in FIG. 1. FIG. 3 is a sectional view taken on line III-III in FIG. 2.
As shown in these drawings, the vehicle headlight 10 of this embodiment is a lighting device arranged on the right of a front end portion of a vehicle. The vehicle headlight 10 is composed in such a manner that eight lighting device units 30, 50, 70, four of them are arranged in the upper step and the other four of them are arranged in the lower step, are accommodated in a lighting chamber including a lamp body 12 and a transparent light transmission cover 14 attached to the front end opening of the lamp body 12. In this vehicle headlight 10, a light distribution pattern for a low beam can be formed by the irradiation of light sent from these eight lighting device units 30, 50, 70.
In the above light chamber, an inner panel 16 is arranged along the light transmission cover 14. At positions on the inner panel corresponding to the lighting device units 30, 50, 70, the cylindrical opening portions 16a surrounding the lighting device units 30, 50, 70 are formed.
All of the eight lighting device units 30, 50, 70 are composed as a projector type lighting device unit. While these eight lighting device units 30, 50, 70 are being attached to the common support member 20, they are tiltably supported by the lamp body 12 via the aiming mechanism 22 so that these eight lighting device units 30, 50, 70 can be tilted in the vertical and the traverse direction.
The unit support member 20 is composed of a die-cast product, for example, an aluminum die-cast product. The unit support member 20 includes: a perpendicular panel portion 20A; a unit attaching portion 20B extending like a shelf to the front from the perpendicular panel portion 20A at a plurality of portions; and a heat sink portion 20C composed of a plurality of radiating fins extending from the perpendicular panel portion 20A to the rear.
The heat sink portion 20C is arranged at two portions, one is a right portion and the other is a left portion. The right and the left heat sing portion are protruded from the two circular opening portions 12a, which are formed on a rear wall of the lamp body 12, to the outer space of the lighting device. A rubber cover 18 for sealing is attached to each opening portion 12a. An inner circumferential portion of the rubber cover 18 is engaged with an outer circumferential base end portion of the heat sink portion 20C, and an outer circumferential portion of the rubber cover 18 is engaged with the opening portion 12a of the lamp body 12.
The optical axes Ax of the lighting device units 30, 50, 70 are extended in parallel with each other in the direction substantially perpendicular to the perpendicular panel portion 20A. After the optical axis adjustment made by the aiming mechanism 22 has been completed, the optical axes Ax of the lighting device units 30, 50, 70 are extended in a downward direction by an angle 0.5 to 0.6° with respect to the longitudinal direction of a vehicle.
The three lighting device units 30, which are among the eight lighting device units 30, 50, 70 and located on the outside in the vehicle width direction in the upper step, are composed as lighting device units for medium diffusion. The three lighting device units 50, which are among the eight lighting device units 30, 50, 70 and located on the outside in the vehicle width direction in the lower step, are composed as lighting device units for condensing light. The two lighting device units 70, which are located at the end portions on the inside in the vehicle width direction in the upper and the lower step, are composed as lighting device units for wide diffusion.
Next, the specific structure of the lighting device units 30, 50, 70 will be explained below.
First, the specific structure of the lighting device units 30 for medium diffusion will be explained as follows.
FIG. 4 is an enlarged view showing a primary portion of FIG. 2 in which the lighting device unit 30 for medium diffusion is shown in detail. FIGS. 5 and 6 are the sectional side view and the sectional plan view. FIG. 7 is a sectional view taken on line VII-VII in FIG. 4. FIG. 8 is an exploded perspective view for explaining an attaching structure in which the lighting device unit 30 for medium diffusion is attached to the unit support member 20.
As shown in these drawings, the lighting device unit 30 for medium diffusion includes: a projection lens 32 arranged on the optical axis Ax; a light emitting element 34 arranged at the rear of this projection lens 32; a reflector 36 arranged so that the reflector 36 can cover this light emitting element 34 from the upper side; and a rectilinear propagation blocking member 38 arranged between the light emitting element 34 and the projection lens 32.
In this lighting device unit 30 for medium diffusion, the projection lens 32 and the rectilinear propagation blocking member 38 are integrally formed as a light control member 40 by means of insertion molding. In this lighting device unit 30 for medium diffusion, the light emitting element 34, the reflector 36 and the light control member 40 are individually attached to the unit attaching portion 20B of the unit support member 20. In this way, the lighting device unit is composed.
The projection lens 32 is a transparent lens made of resin (for example, a transparent lens made of acrylic resin) which is composed as a plano-convex lens, the front surface of which is formed into a convex and the rear surface of which is formed into a plane. The focal distance of the projection lens 32 is f1, which is relatively short.
The light emitting element 34 is a white light emitting diode having a light emitting chip 34a, the size of which is approximately 0.3 to 1 mm square, and supported by the support plate 42 made of metal, the shape of which is a regular hexagon. This light emitting element 34 is attached to the unit attaching portion 20B of the unit support member 20 under the condition that the light emitting chip 34a is arranged being directed perpendicularly upward on the optical axis Ax.
The reflector 36 is composed in such a manner that the light emitted from the light emitting element 34 is reflected to the front side being directed to the optical axis Ax side, so that the light can be substantially converged upon the neighborhood of the rear side focus F of the projection lens 32. Specifically, the reflecting face 36a of this reflector 36 is set in such a manner that the cross section of the reflector 36 including the optical axis Ax is formed into a substantial elliptical shape and that the eccentricity is gradually increased from the perpendicular cross section to the horizontal cross section. This reflecting face 36a is formed so that the light sent from the light emitting element 34 can be substantially converged at a position somewhat ahead of the rear side focus F.
This reflector 36 includes a pair of brackets 36b, one is arranged on the right and the other is arranged on the left. This reflector 36 is fixed being screwed to the unit support member 20 in both the brackets 36b under the condition that the peripheral lower end portion is made to come into contact with an upper face of the unit attaching portion 20B of the unit support member 20.
The rectilinear propagation blocking member 38 is a transparent member made of resin (for example, a member made of resin of polycarbonate). This rectilinear propagation blocking member 38 includes: a main body 38A, the upper face 38a of which is formed into a substantial C-shape when it is viewed from the front of the lighting device; and a lens holder portion 38B formed being extended from the front end portion of the main body 38A to the front of a vehicle.
The upper face 38a of the main body 38A extends to the rear from the rear side focus F of the projection lens 32, and the front end edge 38a1 of the main body 38A is formed into a substantial arc shape along the focal face of the rear side focus F of the projection lens 32. This upper face 38a is formed as follows. A region on the left (on the right when it is viewed from the front of the lighting device) with respect to the optical axis Ax is composed of a plane horizontally extending to the left from the optical axis Ax, and a region on the right with respect to the optical axis Ax is composed of a plane extending from the optical axis Ax to the right obliquely downward (for example, by the angle 15° downward). This upper face 38a is subjected to reflecting face treatment by means of aluminum vapor deposition. Due to the foregoing, a portion of the reflected light sent from the reflecting face 36a of the reflector 36 is prevented from propagating straight by the upper face 38a. The upper face 38a is composed as a reflecting face on which the portion of the reflected light sent from the reflecting face 36a is reflected upward.
The lens holder 38B extends to the front from the front end portion of the main body 38A so that it can be curved downward. The lens holder 38B supports the projection lens 32 by the semicircular positioning groove 38b formed in the front end portion of the lens holder 38B. As described before, this fixing and supporting action can be conducted when the projection lens 32, the rectilinear propagation blocking member 38 and the light control member 40 are integrally formed by means of insertion molding. At this time, while the projection lens 32 is being inserted, the rectilinear propagation blocking member 38 is made by means of injection molding.
In the rectilinear propagation blocking member 38, a pair of brackets 38c, one is arranged on the right and the other is arranged on the left, are formed at the rear end portion of the main body 38A. In a lower portion of the main body 38A of the rectilinear propagation blocking member 38, the positioning pin 38d protruding from the lens holder 38B to the rear is formed. Between the positioning pin 38d and the main body 38A, the perpendicular rib 38e for connecting both the positioning pin 38d and the main body 38A is formed.
On the other hand, the unit attaching portion 20B of the unit support member 20 includes: a light source fixing portion 20B1 for fixing and supporting the light emitting element 34; a pair of boss portions 20B2 arranged on both sides of this light source fixing portion 20B1 while leaving a predetermined interval; a reflector support portion 20B3 arranged between the pair of boss portions 20B2; and a pin receiving portion 20B4 arranged in a lower portion of the light source fixing portion 20B1. The front end face 20a of the unit support member 20 is composed of a plane parallel with the perpendicular panel portion 20A which is perpendicular to the metallic die releasing direction of the unit support member 20.
The reflector support portion 20B3 of this unit attaching portion 20B is formed into a substantial C-shape when it is viewed from the front of the lighting device so that an upper face of the reflector support portion 20B3 can be on the same face as the upper face 38a of the rectilinear propagation blocking member 38.
The pin receiving portion 20B4 of this unit attaching portion 20B is formed at a position opposing to the positioning pin 38d of the rectilinear propagation blocking member 38. Between the pin receiving portion 20B4 and the light source fixing portion 29B1, the perpendicular rib 20c for connecting both of them is provided.
The rectilinear propagation blocking member 38 is screwed and fixed to the unit support member 20 in both the bracket portions 38c under the condition that each bracket 38c and the positioning pin 38d of the main body 38A are made to come into contact with the front end face 20a of the unit attaching portion 20B of the unit support member 20 at the positions of each boss portion 20B2 and the pin receiving portion 20B4.
The above screwing fixation is conducted when the rectilinear propagation blocking member 38 and the reflector 36 are fastened to each other. In order to realize this screwing fixation, the screw insertion holes 36b1, 38c1 for inserting the screw 44 are formed in each bracket 36b of the reflector 36 and each bracket 38c of the rectilinear propagation blocking member 38 on the same straight line. On the front end face 20a of the unit attaching portion 20B of the unit support member 20, the screw hole 20b is formed at the position of each boss portion 20B2.
In each bracket 38c of the rectilinear propagation blocking member 38, the spherical protruding portion 38c2 is formed in the neighborhood of the upper portion of the screw insertion hole 38c1 on the rear face. Due to the foregoing, the screwing fixation of the rectilinear propagation blocking member 38 can be conducted under the condition that three portion of the rectilinear propagation blocking member 38 are contacted with the unit support member 20.
As shown in FIG. 7, a fastening force given at the time of the fixation by screwing acts as a resultant force at the attaching center P of the rectilinear propagation blocking member 38, that is, at the middle point of the line segment connecting the centers of a pair of screw holes 20b of the unit support member 20. This attaching center P is located at the substantial center of a triangle formed by the center of the positioning pin 38d and the centers of the pair of spherical protruding portions 38c2. Therefore, the rectilinear propagation blocking member 38 can be accurately, stably attached to the unit support member 20 by the three-point support structure.
As described before, in the present embodiment, the projection lens 32 and the rectilinear propagation blocking member 38 are formed integrally with each other so that the light control member 40 can be formed. Therefore, when the rectilinear propagation blocking member 38 is attached to the unit support member 20, the projection lens 32 can be simultaneously attached to the unit support member 20.
On the other hand, the light emitting element 34 is fixed to the unit support member 20 in such a manner that the support plate 42 for supporting the light emitting element 34 is press-fitted into the recess groove portion 20d, which is formed in the light source fixing portion 20B1 of the unit attaching portion 20B, from the front side.
Next, the specific structure of the lighting device unit 50 for condensing light will be explained below.
FIG. 9 is a sectional plan view showing the detail of the lighting device unit 50 for condensing light.
As shown in the drawing, the constitution of the light emitting element 54 and the reflector 56 of the lighting device unit 50 for condensing light is completely the same as the constitution of the light emitting element 34 and the reflector 36 of the lighting device unit 30 for medium diffusion. Further, the light control member 60 of the lighting device unit 50 for condensing light is completely the same as the light control member 40 of the lighting device unit 30 for medium diffusion except for the following points.
The focal distance f2 of the projection lens 52 of the light control member 60 is longer than the focal distance f1 of the projection lens 32 of the lighting device unit 30. Corresponding to that, the longitudinal length of the lens holder 58B of the rectilinear propagation blocking member 58 of the light control member 60 is longer than the length of the lens holder portion 38B of the lighting device unit 30.
In the same manner as that of the lighting device unit 30 for medium diffusion, when the light emitting element 54, the reflector 56 and the light control member 60 of the lighting device unit 50 for condensing light are individually attached to the unit attaching portion 20B of the unit supporting member 20, the lighting device unit can be completed.
Next, the specific structure of the lighting device unit 70 for a wide diffusion will be explained below.
FIG. 10 is a sectional plan view showing the detail of the lighting device unit 70 for a wide diffusion.
As shown in the drawing, the structure of the light emitting element 74 and the projection lens 72 of the light control member 80 of this lighting device unit 70 for wide diffusion is completely the same as that of the light emitting element 34 and the projection lens 32 of the lighting device unit 30 for medium diffusion. The structure of the reflector 76 and the rectilinear propagation blocking member 78 of the light control member 80 is completely the same as that of the reflector 36 and the rectilinear propagation blocking member 38 of the lighting device unit 30 for medium diffusion except for the following points.
The essential structure of the reflector 76 is the same as that of the reflector 36. The reflecting face 76a of this reflector 76 is set in such a manner that the cross section of the reflector 76 including the optical axis Ax is formed into a substantial elliptical shape and that the eccentricity is gradually increased from the perpendicular cross section to the horizontal cross section. In this case, a ratio of the increase in the eccentricity of the reflecting face 76a is high compared with the case of the reflector 36. Therefore, the lateral width of the reflector 76 is larger than the lateral width of the reflector 36.
The essential structure of the rectilinear propagation blocking member 78 is the same as that of the rectilinear propagation blocking member 38. The upper face 78a of the main body 78A of the rectilinear propagation blocking member 78 is extended to the rear from the rear side focus F of the projection lens 72. This upper face 78a is subjected to the reflecting face treatment. All region of this upper face 78a is composed of a horizontal face including the optical axis Ax. According to that, the peripheral lower end portion of the reflector 76 and the upper face of the reflector support portion 20B3 of the unit support member 20 are formed into a horizontal face.
In the same manner as that of the lighting device unit 30 for medium diffusion, when the light emitting element 74, the reflector 76 and the light control member 80 of the lighting device unit 70 for wide diffusion are individually attached to the unit attaching portion 20B of the unit supporting member 20, the lighting device unit can be completed.
FIG. 11 is a perspective view showing a light distribution pattern for a low beam formed on a virtual perpendicular screen, which is arranged ahead at a position distant from a lighting device by 25 m, by a beam of light irradiated ahead by the vehicle headlight 10 of the present embodiment.
As shown in the drawing, this light distribution pattern PL for a low beam is a light distribution pattern in which light is distributed to the left. This light distribution pattern PL for a low beam includes: the horizontal cutoff line CL1 at the upper end edge; and the oblique cutoff line CL2 which rises from this horizontal cutoff line CL1 by a predetermined angle (for example, 15°). A position of the elbow point E, which is an intersection of both the cutoff lines CL1 and CL2, is set at a position lower than H-V, which is a vanishing point in the front direction of the lighting device, by the angle of 0.5 to 0.6°. In this light distribution pattern PL for a low beam, the hot zone HZL, which is a region of high luminous intensity, is formed surrounding the elbow point E.
This light distribution pattern PL for a low beam is formed as a compound light distribution pattern including: three light distribution patterns PL1 for medium diffusion formed by the irradiation of light sent from three lighting device units 30 for medium diffusion; three light distribution patterns PL2 for condensing light formed by the irradiation of light sent from three lighting device units 50 for condensing light; and two light distribution patterns PL3 for wide diffusion formed by the irradiation of light sent from two lighting device units 70 for wide diffusion.
As shown in FIG. 12A, in the light distribution pattern PL1 for medium diffusion formed by the irradiation of light sent from the lighting device unit 30 for medium diffusion, as a reverse projected image of the front end edge 38a1 of the upper face 38a of the main body 38A of the rectilinear propagation blocking member 38, the horizontal cutoff line CL1 and the oblique cutoff line CL2 are formed. In this case, the upper face 38a of the main body 38A is composed as a reflecting face. Therefore, as shown by the two-dotted chain line in FIG. 5, a beam of light, which is to be emergent upward from the projection lens 32, in the reflected light reflected on the reflecting face 36a of the reflector 36 can be utilized as a beam of light, which is emergent downward from the projection lens 32 as shown by the solid line in the drawing, by the reflecting action of the upper face 38a. Due to the foregoing, a ratio of utilizing the luminous flux of the light emergent from the light emitting element 34 can be enhanced, and further the hot zone HZL1 can be formed.
As shown in FIG. 12B, in the light distribution pattern PL2 for condensing light formed by the irradiation of light sent from the lighting device unit 50 for condensing light, as a reverse projected image of the front end edge 58a1 of the upper face 58a of the main body 58A of the rectilinear propagation blocking member 58, the horizontal cutoff line CL1 and the oblique cutoff line CL2 are formed. In this case, the upper face 58a of the main body 38A is composed as a reflecting face. Therefore, a beam of light, which is to be emergent upward from the projection lens 52, in the reflected light reflected on the reflecting face 56a of the reflector 56 can be utilized as a beam of light which is emergent downward from the projection lens 52. Due to the foregoing, a ratio of utilizing the luminous flux of the light emergent from the light emitting element 54 can be enhanced, and further the hot zone HZL2 can be formed.
Since the focal distance f2 of the projection lens 52 is longer than the focal distance f1 of the projection lens 32, the light distribution pattern PL2 for condensing light is smaller and brighter than the light distribution pattern PL1 for medium diffusion. The hot zone HZL2 is smaller and brighter than the hot zone HZL1 of the light distribution pattern PL1 for medium diffusion.
On the other hand, in the light distribution pattern PL3 for wide diffusion formed by the irradiation of light sent from the lighting device unit 70 for wide diffusion, as a reverse projected image of the front end edge 78a1 of the upper face 78a of the main body 78A of the rectilinear propagation blocking member 78, the horizontal cutoff line CL1 is formed. In this case, the upper face 78a of the main body 78A is composed as a reflecting face. Therefore, a beam of light, which is to be emergent upward from the projection lens 72, in the reflected light reflected on the reflecting face 76a of the reflector 76 can be utilized as abeam of light, which is emergent downward from the projection lens 72, by the reflecting action of the upper space 78a. Due to the foregoing, a ratio of utilizing the luminous flux of the light emergent from the light emitting element 74 can be enhanced, and further the hot zone HZL3 can be formed.
In the light distribution pattern PL2 for wide diffusion, a ratio of the change of the eccentricity of the reflecting face 76a of the reflector 76 from the perpendicular cross section to the horizontal cross section is set to be higher than that of the reflector 36. Therefore, the diffusion angle in the traverse direction of the light distribution pattern PL2 is larger than that of the light distribution pattern PL1. In this connection, only the horizontal cutoff line CL1 is formed on the upper end edge of the light distribution pattern PL3 for wide diffusion, and the oblique cutoff line CL2 is not formed. The reason is that the upper face 78a of the main body 78A of the rectilinear propagation blocking member 78 is formed to be a horizontal face.
As the detail are described above, in the vehicle headlight 10 of the present embodiment, by the irradiation of light sent from the eight lighting device units 30, 50, 70, the light sources of which are the light emitting elements 34, 54, 74, the light distribution pattern PL for a low beam is formed which has the horizontal cutoff line CL1 and the oblique cutoff line CL2 at the upper end edge. Therefore, the thickness of the lighting device can be reduced.
Since these eight lighting device units 30, 50, 70 are supported by the common unit support member 20, when this unit support member 20 is tilted, the optical axes of these eight lighting device units 30, 50, 70 can be simultaneously adjusted.
In each lighting device unit 30, 50, 70, the projection lens 32, 52, 72 and the rectilinear propagation blocking member 38, 58, 78, which compose the lighting device unit 30, 50, 70, are integrally formed as a light control member 40, 60, 80, and the light control member 40, 60, 80 and the light emitting element 34, 54, 74 are individually attached to the unit support member 20. Therefore, the following operational effects can be provided.
In the lighting device unit 30, 50, 70 composed in such a manner that a portion of light emitted from the light emitting element 34, 54, 74 is prevented from propagating straight by the rectilinear propagation blocking member 38, 58, 78 arranged in the neighborhood of the rear side focus F of the projection lens 32, 52, 72, in order to form a clear cutoff line at a predetermined position with high accuracy, it is very important to ensure the accuracy of the positional relation between the projection lens 32, 52, 72 and the rectilinear propagation blocking member 38, 58, 78. On the other hand, the accuracy of the positional relation between them and the light emitting element 34, 54, 74 is not so important.
Therefore, as described in the present embodiment, when the projection lens 32, 52, 72 and the rectilinear propagation blocking member 38, 58, 78, the accuracy of the positional relation of which must be high, are integrally formed as a light control member 40, 60, 80 and when the light control member 40, 60, 80 and the light emitting element 34, 54, 74 are individually attached to the unit support member 20, the lighting device unit 30, 50, 70 can be completed without affecting the light distribution performance of the lighting device unit 30, 50, 70. When the components of the lighting device unit 30, 50, 70 are individually attached to the unit support member 20, the lighting device structure can be made simple compared with a case in which the completed lighting device unit is attached to the unit support member 20.
As described above, in the present embodiment, while the thickness of the lighting device is being reduced, the optical axes of the eight lighting device units 30, 50, 70 can be simultaneously adjusted without making the structure of the lighting device complicated.
In this case, in the present embodiment, eight lighting device units 30, 50, 70 are composed of three types of units.
They are the lighting device units 30 for medium diffusion, the lighting device units 50 for condensing light and the lighting device units 70 for wide diffusion. Therefore, the light distribution pattern PL for a low beam formed by these lighting device units can be formed as a compound light distribution pattern including the light distribution pattern PL1 for medium diffusion, the light distribution pattern PL2 for condensing light and the light distribution pattern PL3 for wide diffusion. Due to the foregoing, the luminous intensity of the light distribution pattern PL for a low beam can be made uniform.
Further, in the present embodiment, since the unit support member 20 is composed of a die-cast product, the following operational effects can be provided.
When the light emitting element 34, 54, 74 of each lighting device unit 30, 50, 70 emits light, heat is generated from the light emitting element. However, since each light emitting element 34, 54, 74 is attached to the unit support member 20 composed of a die-cast product, heat generated by each light emitting element 34, 54, 74 can be quickly transmitted to the unit support member 20, the heat capacity of which is large, by the action of heat conduction. Due to the foregoing, a temperature rise of the light emitting element 34, 54, 74 can be suppressed. Therefore, it is possible to effectively prevent the luminous flux of the light emitting element 34, 54, 74 from being decreased. It is also possible to prevent the color of emitted light from becoming discolored.
In the present embodiment, since the light control member 40, 60, 80 is composed of an insertion molded product, the following operational effects can be provided.
As described in the present embodiment, when the insertion molding is conducted after the projection lens 32, 52, 72 has been inserted, it is possible to integrate the projection lens 32, 52, 72 and the rectilinear propagation blocking member 38, 58, 78 into one body by the insertion molding after the projection lens 32, 52, 72 has been previously formed as a single body. Due to the foregoing, after the profile accuracy of the projection lens 32, 52, 72 has been sufficiently ensured, the accuracy of the positional relation between the projection lens 32, 52, 72 and the rectilinear propagation blocking member 38, 58, 78 can be sufficiently enhanced.
In the present embodiment, since each of the eight lighting device units 30, 50, 70 includes a reflector 36, 56, 76 for reflecting a beam of light, which is sent from the light emitting element 34, 54, 74, forward so that the beam of light can be substantially converged upon a neighborhood of the rear side focus F of the projection lens 32, 52, 72, it is possible to enhance a ratio of utilizing the flux of light sent from the light emitting element 34, 54, 74. In this case, the reflector 36, 56, 76 is attached to the unit support member 20 by screwing simultaneously when the light control member 40, 60, 80 is screwed and fixed to the unit support member 20. Therefore, the assembling property of assembling the lighting device unit 30, 50, 70 can be enhanced.
In this embodiment, when each of the eight lighting device units 30, 50, 70 has a reflecting face 38a, 58a, 78a, the surface profile of which is predetermined, extending from the neighborhood of the rear side focus F of the projection lens 32, 52, 72 to the rear side, a ratio of utilizing the flux of light emitted from the light emitting element 34, 54, 74 can be further enhanced.
In this connection, instead of adopting the constitution in which the lighting device unit 30, 50, 70 is composed into a projector type lighting device unit having the reflector 36, 56, 76, it is possible to adopt the constitution in which a light-shielding member having a predetermined upper end edge profile corresponding to a cutoff line is arranged as a rectilinear propagation blocking member in the neighborhood of the rear side focus F of the projection lens 32, 52, 72 and a light emitting element is arranged in the neighborhood at the rear of the light-shielding member.
In the above embodiment, the size of the light emitting chip 34a of the light emitting element 34 is approximately 0.3 to 1 mm square. However, it is possible to form the light emitting chip 34a of the light emitting element 34 into the other size and profile. Examples of the size and profile of the light emitting chip 34a of the light emitting element 34 are: a rectangle, the short side of which is 1 mm and the long side of which is 2 mm; and a rectangle, the short side of which is 1 mm and the long side of which is 4 mm. The circumstances are the same with respect to the light emitting chips of the other light emitting elements 54, 74.
In the above embodiment, the vehicle headlight includes: three lighting device units 30 for medium diffusion; three lighting device units 50 for condensing light; and two lighting device units 70 for wide diffusion. However, the numbers of these lighting device units are not limited to the above. Of course, any number of the lighting device units except for the aforementioned numbers can be adopted.
In the vehicle headlight 10 of the above embodiment, only the lighting device unit 30, 50, 70 for forming a light distribution pattern for a low beam is accommodated in the lighting chamber. However, of course, the lighting device unit for forming a light distribution pattern for a high beam can accommodated in the lighting chamber.
In the above embodiment, explanations are made into the vehicle headlight 10 arranged on the right of the front end portion of a vehicle. However, concerning the vehicle headlight arranged on the left of the front end portion of the vehicle, when the same constitution as that of the above embodiment is adopted, the same operational effects as those of the above embodiment can be provided.

## Claims

1. A headlight comprising:
a plurality of lighting device units; and
a unit support member that supports the plurality of lighting device units, wherein each lighting device unit includes:
a projection lens;
a light emitting diode arranged behind a rear side focus of the projection lens; and
a rectilinear propagation blocking member that is arranged in a vicinity of the rear side focus, and blocks a rectilinear propagation of a portion of light emitted from the light emitting diode so as to form a cutoff line,
wherein the projection lens and the rectilinear propagation blocking member are integrally formed as a light control member in each lighting device unit,
wherein each lighting device unit is supported on the unit support member by individually attaching the light control member and the light emitting diode to the unit support member, the light control member being attached to the unit support member by attaching the rectilinear propagation blocking member to the unit support member, and
wherein respective light control members of the plurality of lighting device units are individually attached to the unit support member,
wherein an optical axis of the light emitting diode is perpendicular to an optical axis of the projection lens.

2. The headlight according to claim 1, wherein the plurality of lighting device units are configured to irradiate light such that a predetermined light distribution pattern is formed, and wherein the predetermined light distribution pattern has a cutoff line formed at an upper end edge of the predetermined light distribution pattern.

3. The headlight according to claim 1, wherein the unit support member comprises a die-cast product.

4. The headlight according to claim 1, wherein the light control member comprises an insertion molded product.

5. The headlight according to claim 1, wherein the light emitting diode is disposed on an optical axis of the projection lens.

6. The headlight according to claim 1, wherein at least one of the plurality of lighting device units includes a reflector, and wherein light emitted by the light emitting diode is reflected by the reflector forward and is substantially converged upon a vicinity of the rear side focus.

7. The headlight according to claim 6, wherein the rectilinear propagation blocking member of the at least one of the plurality of lighting device units including the reflector further includes a reflecting face, wherein a surface profile of the reflecting face extends from the vicinity of the rear side focus to the rear of the rectilinear propagation blocking member, and some light reflected by the reflector is reflected on the reflecting face.