Abstract:
A projector headlight for a low beam can include a light source, an ellipsoidal reflector, a projector lens and a shade. Light emitted from the light source can form a fundamental light distribution pattern from the projector lens via the ellipsoidal reflector by shielding an upward portion of the light with the shade. The shade can form a blurred part on a horizontal cut-off line using a radiused R surface between a top and front edge lines of the shade. Therefore, a contrasting difference between the upper and lower sides of the horizontal cut-off line can be reduced so as to be able to conform to a light distribution standard for a headlight. The R surface can be configured with a reflex surface or a non-reflex surface to match the light source. Thus, the projector headlight can perform a favorable light distribution pattern utilizing a simple structure.

Description:
This application claims the priority benefit under 35 U.S.C. §119 of Japanese Patent Application No. 2009-135504 filed on Jun. 4, 2009, which is hereby incorporated in its entirety by reference. 
     BACKGROUND 
     1. Field 
     The presently disclosed subject matter relates to a vehicle headlight of a projector type, and more particularly to a projector headlight for a low beam having a favorable light distribution pattern that can conform to a light distribution standard for a headlight with respect to a contrasting difference between the upper and lower sides of a horizontal cut-off line in the light distribution pattern. 
     2. Description of the Related Art 
     A projector headlight for a low beam and/or a high beam is frequently incorporated into a vehicle lamp including a position lamp, a turn-signal lamp, etc. The projector headlight may allow a light-emitting area thereof to be reduced and therefore allows a vehicle lamp that includes such a projector headlight to be minimized in comparison with other types of headlights. In addition, when an LED is used as a light source for the projector headlight, a battery friendly and small projector headlight can be achieved. 
     A projector headlight is also disclosed in Applicant&#39;s co-pending patent application, U.S. patent application Ser. No. 12/794,488, filed on same date, Jun. 4, 2010, which is hereby incorporated in its entirety by reference. 
     A conventional projector headlight for use as a low beam light is disclosed in patent document No. 1 (Japanese Patent Application Laid Open JP2003-317513).  FIG. 12  is a schematic side cross-section view depicting a structure for the conventional projector headlight in patent document No. 1, and an LED is used as a light source of this projector headlight. 
     According to the conventional projector headlight  50  shown in  FIG. 12 , the projector headlight  50  includes: an LED light source  52 ; an elliptical reflector  54  in which a first focus thereof is located near the LED light source  52 ; a projector lens  56  which has a focus thereof located near a second focus of the elliptical reflector  52 ; and a shade  58  located near the focus of the projector lens  56 . Thus, an optical axis Z 50  approximately corresponds with the respective optical axes of the elliptical reflector  54  and the projector lens  56 , and the LED light source  52 . 
     In the projector headlight  50 , light emitted from the LED light source  52  is reflected on the elliptical reflector  54  and can be emitted in a forward direction of the projector headlight  50  via the projector lens  56 . In this case, a part of the light that is reflected on the elliptical reflector  54  can be shielded by the shade  58 . Accordingly, the projector headlight  50  can form a light distribution pattern for a low beam including a cut-off line in accordance with a top shape of the shade  58 . 
     However, because the shade  58  is substantially located at the focus of the projector lens  56 , a contrasting difference between the upper and lower sides of a horizontal cut-off line of an oncoming lane and of a driving lane in the light distribution pattern tends to become too clear. When the light-emitting area of the projector headlight  50  becomes smaller and/or the brightness thereof becomes brighter using a high power light source and/or the like, the contrasting difference may be especially enhanced and too clear. Thus, the projector headlight  50  may include a problem in that the excessive contrasting difference thereof causes a decrease of visibility in some cases. 
     In order to reduce the contrasting difference, another conventional projector headlight for use as a low beam light is disclosed in patent document No. 2 (Japanese Patent Application Laid Open JP2008-262755).  FIG. 13  is a schematic side cross-section view depicting a projector lens for the other conventional projector headlight that is disclosed in patent document No. 2. According to this projector headlight, on a surface towards a focus F 68  of a projector lens  66 , convex surfaces are provided as a means to diffuse light that forms a cut-off line in a light distribution pattern. The convex surfaces may blur the cut-off line, and therefore may improve visibility in the light distribution pattern. 
     The above-referenced Patent Documents are listed below and are hereby incorporated with their English abstract in their entirety. 
     1. Patent document No. 1: Japanese Patent Application Laid Open JP2006-317513 
     2. Patent document No. 2: Japanese Patent Application Laid Open JP2008-262755 
     However, when diffusing light by a surface of the projector lens like the projector lens that is disclosed in patent document No. 2, the surface of the projector lens may effect a change in light other than that near the cut-off line, and therefore may cause a decrease of a maximum light intensity and/or a glare. In addition, it may be difficult to form convex surfaces on the surface of the projector lens during a manufacturing process, especially when the projector lens is made of a glass material, it may be very difficult because the process may become the last process. 
     The disclosed subject matter has been devised to consider the above and other problems, characteristics and features. Thus, an embodiment of the disclosed subject matter can include a projector headlight for a low beam having a favorable light distribution pattern that can conform to a light distribution standard for headlights with respect to a contrast difference between the upper and lower sides of a horizontal cut-off line. In this case, various light sources such as a semiconductor light source, an HID lamp, a halogen bulb and the like can be employed as a light source with a simple structure. 
     SUMMARY 
     The presently disclosed subject matter has been devised in view of the above and other characteristics, desires, and problems in the conventional art, and to make certain changes to existing projector headlights. Thus, an aspect of the disclosed subject matter includes providing a projector headlight for a low beam having a favorable light distribution pattern that can conform to a light distribution standard for headlights with respect to a contrast difference between the upper and lower sides of a horizontal cut-off line, wherein various light sources can be used as a light source with a simple structure and the basically same structure. Another aspect of the disclosed subject matter includes providing a projector headlight using an LED light source, which can result in a battery friendly and small projector headlight having a favorable light distribution pattern so that it can be used for various types of vehicles including an electric car and the like. 
     According to an aspect of the disclosed subject matter, a projector headlight can include a light source, at least one ellipsoidal reflector, a projector lens and a shade. At least the ellipsoidal reflector can have a first focus and a second focus, the first focus thereof being located near the light source. The projector lens can have both a focus and an optical axis thereof located substantially on an imaginary line connecting the first focus and the second focus of the at least one ellipsoidal reflector. The shade can comprise a neutral point and first, second and third top edge lines that respectively face first, second and third front edge lines with respect to each other. The shade can have the neutral point located near the focus of the projector. The first, second and third top edge lines can be configured to form a horizontal cut-off line with light emitted from the light source, and an R surface between the first, second and third top edge lines and the first, second and third front edge lines can be configured to slant down in a direction towards the projector lens. The R surface can be configured to form a continuous blur portion on the horizontal cut-off line. 
     In the above-described exemplary projector headlight, the light emitted from the light source can form a fundamental light distribution pattern from the projector lens via the ellipsoidal reflector by shielding an upwardly directed light with the shade. In this case, because light that is reflected on the R surface underneath the first, second and third top edge lines that form the horizontal cut-off line can illuminate a position on the horizontal cut-off line, a position on the horizontal cut-off line can become dark. Accordingly, contrast difference between the upper and lower sides of the horizontal cut-off line can be reduced. In addition, because the first top edge line can be located at a higher position than the second top edge line, the first, second and third top edge lines can form a cut-off line for a driving lane, an oncoming lane and an elbow line, respectively. 
     In this case, the R surface can be configured to form a circular shape, and a radius and/or a position of the R surface can change. Therefore, according to a light distribution standard for a headlight, characteristics of the blur portion such as width, thickness, brightness and the like can be adjusted. In addition, the R surface can be configured with a reflex surface or a non-reflex surface (i.e., a reflective surface or a non-reflective surface) to match characteristics of various light sources such as a semiconductor light source, an HID lamp, a halogen bulb, etc. 
     Furthermore, second focuses of other ellipsoidal reflectors other than at the least one ellipsoidal reflector can be located substantially on the second top edge line of the shade and a virtual extending line of the second top edge line. Thus, the projector headlight of the disclosed subject matter can form a favorable light distribution with a wide range and a simple structure, and the structure can be the basically the same even if various and different light sources are used as a light source(s). 
     According to another aspect of the disclosed subject matter, a projector headlight can include: an LED light source having an optical axis located on a base board; at least one ellipsoidal reflector having a first focus and a second focus, and attached to the base board so that the first focus thereof can be located substantially at the LED light source; a projector lens having both a focus and an optical axis located substantially on an imaginary line that connects the first focus and the second focus of the at least one ellipsoidal reflector, and the focus of the projector lens being located substantially at the second focus of the at least one ellipsoidal reflector; a shade; and a housing attaching the projector lens, the shade and the at least one ellipsoidal reflector. 
     In the above-described projector headlight, because the structure of the shade, the ellipsoidal reflector and the projector lens can be substantially the same, the projector headlight using the LED light source can perform the features set forth above in paragraphs [0013]-[0016]. In addition, the optical axis of the LED light source can intersect with the imaginary line of the projector lens substantially at the first focus of the at least one ellipsoidal reflector so as to correspond with each other in a vertical direction. An intersecting angle of the optical axis of the LED light source and the imaginary line of the projector lens towards the at least one ellipsoidal reflector can be smaller than the intersecting angle towards the projector lens. 
     Therefore, the projector headlight can improve a faraway (or distance) visibility because light emitted from the LED light source can illuminate at the faraway point. Moreover, second focuses of other ellipsoidal reflectors other than at least the ellipsoidal reflector can also be located substantially on the first top edge line of the shade and the second top edge line in order to improve a light use efficiency. Thus, the disclosed subject matter can provide a small projector headlight that can perform a favorable light distribution pattern with a high efficiency and low power consumption, and which can be used for an electrical car and the like. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other characteristics and features of the disclosed subject matter will become clear from the following description with reference to the accompanying drawings, wherein: 
         FIG. 1  is a schematic side cross-section view showing an exemplary structure of a vehicle headlight of a projector type for a low beam made in accordance with principles of the disclosed subject matter; 
         FIG. 2  is a partial schematic close-up view showing a shade for the projector headlight shown in  FIG. 1  and is a perspective view from a front top of the shade; 
         FIG. 3   a  and  FIG. 3   b  are schematic diagrams showing fundamental light distribution patterns formed on a virtual screen that is vertically located at 25 meters away from the projector headlight of  FIG. 1 , wherein a conventional shade and an exemplary shade made in accordance with the disclosed subject matter are used as shades used in  FIG. 3   a  and  FIG. 3   b , respectively; 
         FIG. 4   a  and  FIG. 4   b  are partial close-up side cross-section views showing the exemplary shade made in accordance with the disclosed subject matter and the conventional shade, respectively; 
         FIG. 5  is a graph showing a relation between an angle in a horizontal direction and a light intensity of a light distribution near a cut-off line with respect to projector headlights using an exemplary shade according to the disclosed subject matter and a conventional shade; 
         FIG. 6  is a partial schematic enlarged view depicting another exemplary shade and is a perspective view from a front top of the shade, which blurs the light intensity within a prescribed range of a cut-off line; 
         FIG. 7  is an explanatory schematic diagram showing a fundamental light distribution pattern formed by the shade shown in  FIG. 6 ; 
         FIG. 8  is a schematic cross-section view depicting another exemplary vehicle headlight of a projector type for a low beam made in accordance with principles of the disclosed subject matter; 
         FIG. 9   a  and  FIG. 9   b  are partial close-up side cross-section views showing another exemplary shade made in accordance with the disclosed subject matter and another conventional shade, respectively; 
         FIG. 10  is a graph showing a relation between an angle in a horizontal direction and a light intensity of a light distribution near a cut-off line with respect to projector headlights using the exemplary shade of  FIG. 9   a  and the conventional shade of  FIG. 9   b;    
         FIG. 11  is a schematic diagram showing a fundamental light distribution pattern formed on a virtual screen that is vertically located at 25 meters away from the projector headlight of  FIG. 8 , wherein the exemplary shade of  FIG. 9   a  is used as a shade; 
         FIG. 12  is a schematic side cross-section view depicting a structure for a conventional projector headlight in which an LED is used as a light source; and 
         FIG. 13  is a schematic side cross-section view depicting a projector lens for another conventional projector headlight. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The disclosed subject matter will now be described in detail with reference to  FIG. 1  to  FIG. 11 .  FIG. 1  is a schematic side cross-section view showing an exemplary vehicle headlight of a projector type for a low beam made in accordance with principles of the disclosed subject matter. The projector headlight  10  for a low beam can include: a semiconductor light source  12 , a reflector  14 , a projector lens  16  and a shade  18 . 
     The semiconductor light source  12  can be, for example, a white LED which is attached to a base board  19  so that an optical axis of the semiconductor light source  12  can slant in the opposite direction of the projector lens  16 . Other semiconductor devices such as a laser can also be used as the semiconductor light source  12 . 
     The reflector  14  can be located so as to cover the semiconductor light source  12 . An inner surface of the reflector  14  can be configured with a reflex surface  14   a  in a free surface shape based on a plurality of ellipsoidal reflex surfaces. Therefore, the reflex surface  14   a  can be basically ellipsoidal having a first focus and a second focus, and the first focus can be located at substantially the semiconductor light source  12  so that light emitted from the semiconductor light source  12  can concentrate at the second focus through the reflex surface  14   a.    
     The second focus of the reflex surface  14   a  can be located near a focus F of the projector lens  16 . Thus, an optical axis of the projector headlight  10  can substantially correspond to an optical axis of the projector lens  16  including the focus F, the semiconductor light source  12 , and the first and second focus of the reflex surface  14   a . Light emitted from the semiconductor light source  12  can be illuminated as an inverted light in a forward direction of the projector headlight  10  via the projector lens  16 . 
     When the projector headlight  10  is used in low beam mode using the above-described structure, the projector headlight  10  can include the shade  18  in order to shield an upward light that may give a glaring type light to an oncoming car and the like. The shade  18  can include a horizontal plate  18   a , a vertical plate  18   b  and a top edge  18   c . A surface treatment for reflecting light such as an aluminum deposition, a silver coating and the like can be formed on the horizontal plate  18   a  so that light arriving at the horizontal plate  18   a  can be reflected towards the projector lens  16 . 
     The top edge  18   c  can be located between the horizontal plate  18   a  and the vertical plate  18   b , and can be configured to form a horizontal cut-off line for an oncoming lane and for a driving lane. The shade  18  can be located so that the focus F of the projector lens  16  can be located at or near (i.e., substantially at) the top edge  18   c  thereof. Therefore, the projector headlight  10  can form a light distribution pattern for a low beam with light emitted from the semiconductor light source  12  through the shade  18  and the projector lens  16 . 
     The shade  18  will now be described in detail.  FIG. 2  is a partial perspective close-up view showing the shade  18  for the projector headlight  10  shown in  FIG. 1  and is a perspective view from a front top of the shade  18 . The horizontal plate  18   a  of the shade  18  can include a top surface  18   a   1 , and the vertical plate  18   b  can include a front surface  18   b   1 . An end of the top surface  18   a   1  towards the front surface  18   b   1  can include or constitute the top edge  18   c.    
     The top edge  18   c  can be formed in a substantially circular arc shape as viewed from a top view of the shade  18 , and can be configured to form a top line of the horizontal cut-off line. The top edge  18   c  can include: a first top edge line  18   c   1  for forming the top line of the horizontal cut-off line for an oncoming lane, a second top edge line  18   c   2  for forming the top line of the horizontal cut-off line for a driving lane, and a third top edge line  18   c   3  that is located between the first top edge line  18   c   1  and the second top edge line  18   c   2  for forming the top line of an elbow line on the cut-off line near a vertical line. 
     In addition, an R surface  20 , for example a radiused surface, can be formed between the top edge  18   c  and an edge of the front surface  18   b   1  that includes a first front edge line, a second front edge line and a third front edge line so as to face the first top edge line  18   c   1 , the second top edge line  18   c   2  and the third top edge line  18   c   3 , respectively. Moreover, a height of the first top edge line  18   c   1  of the top edge  18   c  can be higher than that of the second top edge line  18   c   2  in a side view from the projector lens  16 . Therefore, the third top edge line  18   c   3  can slant between the first top edge  18   c   1  and the second top edge  18   c   2 . 
       FIG. 3   a  is a schematic diagram showing a fundamental light distribution pattern formed on a virtual screen that is vertically located at 25 meters away from the projector headlight, which includes a conventional shade without the R-surface  20  shown in  FIG. 2 . The fundamental light distribution pattern PL can include a horizontal cut-off line CL 1  on the oncoming lane that is formed by the first top edge line  18   c   1  of the shade  18 . The horizontal cut-off line CL 1  can be formed downward than a horizontal line H due to the oncoming lane. 
     The fundamental light distribution pattern PL can include a horizontal cut-off line CL 2  on the driving lane that is formed by the second top edge line  18   c   2 . The horizontal cut-off line CL 2  can be formed substantially on the horizontal line H because of the driving lane. In addition, the fundamental light distribution pattern PL can include an elbow line CL 3  between the horizontal line CL 1  for the oncoming lane and the horizontal line CL 2  for the driving lane, which is formed by the third top edge line  18   c   3 . 
     In this case, the shade  18  can include a neutral point that is an intersection of a virtual extending line of the second top edge line  18   c   2  and another virtual line that passes at a intersection of the first top edge line  18   c   1  and the third top edge line  18   c   3  and intersects with the virtual extending line of the second top edge line  18   c   2  at a right angle. The neutral point can be located substantially at the focus F of the projector lens  16  so that the first and second top edge liens  18   c   1 ,  18   c   2  can be configured to form the horizontal cut-off line for both a driving lane and an oncoming lane with the light emitted from the semiconductor light source  12 . 
       FIG. 3   b  is a schematic diagram showing a fundamental light distribution pattern formed on the virtual screen that is vertically located at 25 meters away from the projector headlight, which includes the shade  18 . In this case, a continuous blur portion P can be formed on the horizontal cut-off line CL 1 -CL 3  by the R surface. A principle of the continuous blur portion P will now be described in detail with reference to  FIG. 4   a  and  FIG. 4   b .  FIG. 4   a  and  FIG. 4   b  are partial close-up side cross-section views showing the shade  18  and a conventional shade, respectively. 
     The conventional shade  24  shown in  FIG. 4   b  includes: a horizontal plate  24   a ; a top surface  24   a   1  located on the horizontal plate  24   a ; a top edge line being an end of the top surface  24   a   1 ; a vertical plate  24   b ; and a front surface  24   b   1  located on the vertical plate  24   b  that is substantially perpendicular to the horizontal plate  24   a . A mark  24 C(F) shows a point on the top edge line of the end of the top surface  24   a   1 , and the top edge line of the end of the top surface  24   a   1  can form the horizontal cut-off line CL 1 -CL 3  in the light distribution pattern PL as shown in  FIG. 3   a.    
     The shade  18  shown in  FIG. 4   a  can include a point  18 C (F) on the top edge  18   c  corresponding to the point  24 C (F) shown in  FIG. 4   a . The horizontal plate  18   a  can extend toward the projector lens  16  from the top edge  18   c  including the point  18 C(F), and the R surface  20  can be located in a circular arc shape between the top edge  18   c  and the front surface  18   b   1  so as to extend along the top edge  18   c  and the front surface  18   b   1 . A surface treatment for reflecting light can be formed on the R surface  20  as well as the top surface  18   a   1 . The R surface  20  can result in the continuous blur portion P as shown in  FIG. 3   b.    
     More specifically, light rays A, B and C can be caused to intersect at a point M shown in  FIG. 4   a . With regard to  FIG. 4   b , the point M is located at a distances d away from the point  24 C (F) in an upwards direction of the point  24 C (F). The ray A emitted from the semiconductor light source  12  intersects with the point M and passes over the point  24 C (F). The ray B intersects with the point M at an angle that is nearly equal to 0 degree with respect to the top surface  24   a   1 , and passes over the point  24 C(F). The ray C is reflected on the top surface  24   a   1  and passes at the point M. 
     In this case, when each of the projector headlights include the shade  18  shown in  FIG. 4   a  or the shade  24  shown in  FIG. 4   b , each of the rays B passes at the point M without a contact with the shades  18  and  24 , respectively, and enters into the projector lens  16 . Then, each of the rays B that passes over the shades  18  and  24  may be emitted toward the substantially same position under the horizontal cut-off line through the projector lens  16 , respectively. 
     Each of the rays C passes at the point M after reflecting on the shades  18  and  24 , and enters into the projector lens  16 , respectively. Then, each of the rays C that reflect on the shades  18  and  24  may be emitted slightly upwards through the projector lens  16 , respectively. The ray A shown in  FIG. 4   b  that passes at the point M over the shade  24  can be emitted under the horizontal cut-off line through the projector lens  16 . 
     On the other hand, the ray A shown in  FIG. 4   a  that passes at the point M gets to the R surface  20 , and may be reflected on the R surface. The ray A can be emitted from the projector lens  16  as a ray emitted under the top edge  18   c , and therefore can be emitted on or slightly over the horizontal cut-off line through the projector lens  16 . Thus, the light that is reflected on the R surface  20  can basically form the continuous blur portion P on the horizontal cut-off line CL 1 -CL 3 . In this case, the nearer (smaller) the distance d is, the larger the ray forming the blur portion P is. 
       FIG. 5  is a graph showing a relation between an angle in a horizontal direction and a light intensity of a light distribution near the cut-off line with respect to projector headlights using the shade  18  as compared with the conventional shade  24 . When the conventional shade  24  is used, a slant of the light intensity becomes sharp near the cut-off line. When the shade  18  of the disclosed subject matter is used in the projector headlight  10 , the slant of the light intensity can become moderate near the horizontal cut-off line. 
     That is to say, the intensity of the light distribution pattern in accordance with the disclosed subject matter can be slightly decreased underneath the horizontal cut-off line as compared to that of the conventional light distribution pattern. In addition, the intensity of the light distribution pattern in accordance with the disclosed subject matter can be slightly increased on the horizontal cut-off line. Thus, the shade  18  of the disclosed subject matter can result in the continuous blur portion P near the horizontal cut-off line of the light distribution pattern. 
     The above-description assumes that both the top edge  18   c  of the shade  18  and the top edge  24   c  of the conventional shade  24  correspond to (are located substantially at) the focus F of the projector lens  16 . However, even when both top edges  18   c  and  24   c  do not correspond to the focus F of the projector lens  16 , the continuous blur portion P near the horizontal cut-off line can be formed by the R surface  20  that is provided underneath the top edge  18   c . Thus, the project headlight  10  of the disclosed subject matter can form the continuous blur portion P on the horizontal cut-off line CL 1 -CL 3  as shown in  FIG. 3   b  with the diffusing light that is reflected on the R surface  20 . 
     According to a vehicle headlight standard (for example, ECE Regulation), a maximum light intensity of H-V point (an intersection of the horizontal line H and the vertical line V shown in  FIG. 3   a ) in front of a headlight is established so that the headlight is prevented from producing glare towards an oncoming car and/or pedestrian. When a central portion of the cut-off line in the light distribution pattern shown in  FIG. 3   a  is provided with the blur effect by the above-described R surface, the diffusing light reflected from the R surface may exceed the reference of the maximum light intensity due to an increase of the light intensity. 
     Therefore, the shade  18  can be made so as not to cause such a problem. For example, the R surface  20  can be designed so that the R surface is not formed near a part of the top edge  18   c  that corresponds to such a region of the cut-off line, or so that the R surface having a small radius is formed near the part of the top edge  18   c . In addition, the R surface can be formed only within a prescribed range in order to be able to conform to a standard with regard to a light intensity of a cut-off line for a headlight. 
       FIG. 6  is a partial schematic enlarged view depicting another exemplary shade and is a perspective view from a front top of the shade  18 , which blurs the light intensity within the prescribed range of the cut-off line. The R surface  20  can be formed from 1 millimeter away from a point between the second and third top edge lines  18   c   2  and  18   c   3 , to 4 millimeters away from that point. Another R surface  22  that has a smaller radius than that of the R surface  20  can be formed out of the range of the above R surface  20 . 
       FIG. 7  is an explanatory schematic diagram showing a fundamental light distribution pattern formed by the shade  18  shown in  FIG. 6 . A blur portion A corresponding to the above-described R surface  20  can be formed near a part of the cut-off line CL 1 . A radius of other R surface between the R surfaces  20  and  22  shown in  FIG. 6  changes from the large radius of the R surface  20  to the small radius of the R surface  22  by certain degrees. A degree of the blur portion can be adjusted by the above-described structure carefully in accordance with a headlight standard. 
       FIG. 8  is a schematic cross-section view depicting another exemplary vehicle headlight of a projector type for a low beam made in accordance with principles of the disclosed subject matter. A projector headlight  30  for a low beam can include: a light source unit  33  including a light source  32 , a reflector  34 , a projector  36  and a shade  38 . 
     The light source  32  can be a high intensity discharge lamp (HID) lamp, a halogen bulb, etc. The reflector  34  can be located so as to cover the light source  32 . An inner surface of the reflector  34  can be configured with a reflex surface  34   a  configured in a free surface shape based on a plurality of ellipsoidal reflex surfaces. Therefore, the reflex surface  34   a  can be basically ellipsoidal having a first focus and a second focus, and the first focus can be located at substantially the light source  32  so that light emitted from the light source  32  can concentrate at the second focus through the reflex surface  34   a.    
     The second focus of the reflex surface  34   a  can be located near a focus F of the projector lens  36 . Thus, an optical axis of the projector headlight  30  can substantially correspond to an optical axis of the projector lens  36  including the focus F, the light source  32 , and the first and second focus of the reflex surface  34   a . Light emitted from the light source  32  can be illuminated as an inverted light in a forward direction of the projector headlight  30  via the projector lens  36 . 
     The projector headlight  30  can include the shade  38  in order to shield an upward light that may give a glaring type light to an oncoming car and the like, and therefore can form the light distribution pattern PL for a low beam as shown in  FIG. 3   a . The shade  38  can include a top surface  38   a , a front surface  38   b  and a top edge  38   c  that can be configured to form a cut-off line CL 1 -CL 3  on the light distribution pattern PL. 
     The shade  38  of the projector headlight  30  can be made of an aluminum material such as an aluminum die cast material, steel plate cold (SPC), etc. However, a surface treatment may not be carried out, unlike with the shade  18  in which surface treatment can be carried out.  FIG. 9   a  and  FIG. 9   b  are partial close-up side cross-section views showing another exemplary shade made in accordance with the disclosed subject matter and another conventional shade, respectively. 
     The conventional shade  44  shown in  FIG. 9   b  includes: a top surface  44   a ; a top edge being an end of the top surface  44   a ; and a front surface  44   b  located substantially perpendicular to the top surface  44   a . A mark  44 C(F) shows a point on the top edge of the end of the top surface  44   a , and the top edge of the end of the top surface  44   a  can form the horizontal cut-off line CL 1 -CL 3  in the light distribution pattern PL as shown in  FIG. 3   a.    
     The shade  38  shown in  FIG. 9   a  can include a point  38 C (F) on the top edge corresponding to the point  44 C (F) shown in  FIG. 9   b . The horizontal plate  38   b  can extend toward the projector lens  16  from the top edge including the point  38 C(F), and R surface  40  can be configured in a circular arc shape and located between the top edge line and the front surface  38   b  so as to extend along the top edge and the front surface  38   b   1 . A surface treatment for reflecting light may not be formed on the R surface  40  but rather a surface treatment for absorbing light can be formed on the R surface  40 . The R surface  40  can result in the continuous blur portion P as shown in  FIG. 3   b.    
     More specifically, rays A, B and C may intersect with a point M shown in  FIG. 9   b . The point M is located at a distances d away from the point  44 C (F) in an upwards direction of the point  44 C (F). The ray A emitted from the light source  32  intersects with the point M and passes over the point  44 C (F). The ray B intersects with the point M at an angle that is nearly equal to 0 degree with respect to the top surface  44   a , and passes over the point  44 C(F). If the top surface  44   a  is formed with a reflex surface, the ray C may be reflected on the top surface  44   a  and may pass at the point M. 
     In this case, when each of the shade  38  shown in  FIG. 9   a  and the shade  44  shown in  FIG. 9   b  is used as a shade, each of the rays B passes at the point M without contact with the shades  38  and  44 , respectively, and enters into the projector lens  36 . In this case, each of the rays B that passes over the shades  38  and  44  may be emitted toward the substantially same position under the horizontal cut-off line through the projector lens  36 , respectively. 
     However, each of the rays C gets to the shades  38  and  44 , and may be absorbed in the shades  38  and  44  without entering into the projector lens  36 , respectively. On the other hand, the ray A shown in  FIG. 9   b  that passes at the point M over the shade  44  can be emitted under the horizontal cut-off line through the projector lens  36 . However, the ray A shown in  FIG. 9   a  gets to the R surface  40  and may be absorbed in the shade  38 . Therefore, the shade  38  of the disclosed subject matter can decrease light emitted near the horizontal cut-off line by using the R surface  40  that is a non-reflex surface as compared with the other conventional shade  44 . 
       FIG. 10  is a graph showing a relation between an angle in a horizontal direction and a light intensity of a light distribution near a horizontal cut-off line with respect to projector headlights using the exemplary shade of  FIG. 9   a  and the conventional shade of  FIG. 9   b . When the conventional shade  44  is used, a slant of the light intensity becomes sharp near the cut-off line. However, when the shade  38  of the exemplary embodiment is used in the projector headlight  10 , the slant of the light intensity can become moderate near the horizontal cut-off line. 
     That is to say, the intensity of the light distribution pattern in accordance with the disclosed subject matter can be slightly decreased underneath the horizontal cut-off line as compared to that of the conventional light distribution pattern. In addition, the intensity of the light distribution pattern can also be slightly increased on the horizontal cut-off line. Thus, the shade  38  of the disclosed subject matter can also allow forming of the continuous blur portion P near the horizontal cut-off line of the light distribution pattern because of the action in which light is absorbed on the R surface  40 . 
     The above description is set forth so that both the top edge point  38 C (F) of the shade  38  and the top edge point  44 C (F) of the conventional shade  44  correspond to the focus F of the projector lens  36 . However, even when both top edge points  38 C (F) and  44 C (F) do not correspond to the focus F of the projector lens  36 , the continuous blur portion P near the horizontal cut-off line can be formed by the R surface  40  that is provided underneath the top edge  38   c.    
     Thus, the projector headlight  10  of the disclosed subject matter can form the continuous blur portion P′ underneath a horizontal cut-off line CL 1 -CL 3  of a light distribution pattern PL as shown in  FIG. 11  when the R surface  40 , which is a non-reflex surface, is used to absorb light. Furthermore, in the above-described exemplary embodiment, the R surface  40  can also be formed within a prescribed range as shown and described with respect to  FIG. 6 . 
     A projector headlight using the LED light source and the shade  18  will now be given. The projector lens  16  and the shade  18  can be attached to a housing so that the neutral point of the shade  18  can be located substantially at the focus F of the projector lens  16 , and so that the top edge  18   c  can be substantially bilaterally symmetric with respect to the optical axis of the projector lens  16  in the top view of the shade  18 . 
     At least one ellipsoidal reflector having the first focus and the second focus can be attached to the base board  19  so that the first focus thereof can be located substantially at the LED light source, which is mounted on the base board  19 . The at least one ellipsoidal reflector can be attached to the housing along with the base board  19  and projector lens  16  so that the optical axis of the LED light source can intersect with an imaginary line of the projector lens  16  that connects the first and second focuses of the ellipsoidal reflector to the optical axis of the projector lens  16 , substantially at the first focus of at least the ellipsoidal reflector so as to correspond to each other in a vertical direction. 
     In this case, when an intersecting angle of the optical axis of the LED light source and the imaginary line of the projector lens  16  towards the at least one ellipsoidal reflector is smaller than the intersecting angle towards the projector lens  16 , because a strong light near the optical axis of the LED light source can be reflected on a rearward part of the reflex surface  14   a  that is located on the opposite side of the projector lens  16 , the projector headlight  10  can improve faraway or distance visibility. 
     In addition, second focuses of other ellipsoidal reflectors (other than the at least one ellipsoidal reflector) can be located substantially on the second top edge line  18   c   2  of the shade  18  and a virtual extending line of the second top edge line  18   c   2 . Thereby, the projector headlight  10  may not concentrate light emitted from the LED light source at a central portion of the horizontal cut-off line, and can form a favorable light distribution pattern with a wide range. 
     However, the above-described structure may make it difficult to control light between the first top edge line  18   c   1  and the virtual extending line of the second top edge line  18   c   2 , although such an ellipsoidal reflector may be easy to design and make. In addition, the structure may waste light in some cases because the second focuses of the ellipsoidal reflectors are located on the virtual extending line of the second top edge line  18   c   2 , which is located under the first top edge line  18   c   1 . 
     Consequently, the second focuses of the other ellipsoidal reflectors other than the at least one ellipsoidal reflector can be located substantially on the first top edge line  18   c   1  of the shade  18  and the second top edge line  18   c   2 . In this case, the projector headlight  10  can provide a favorable light distribution pattern having a wide range and a high efficiency. Thus, the disclosed subject matter can provide a small projector headlight using the LED light source having low power consumption and a high efficiency, which can be employed for vehicles such as an electric car and the like. 
     Various modifications of the above disclosed embodiments can be made without departing from the spirit and scope of the presently disclosed subject matter. For example, the above-described R surface of the shade may not be limited to the circular arc shape. Instead, various shapes such as a slanted planar surface, an ellipsoidal surface, a parabolic surface and the like can be used as the R surface. 
     While there has been described what are at present considered to be exemplary embodiments of the invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claims cover such modifications as fall within the true spirit and scope of the invention. All conventional art references described above are herein incorporated in their entirety by reference.