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(11) | EP 1 286 106 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Vehicle headlight |
| (57) A vehicle headlight (1) has a light source (2), first and second ellipse group reflecting
surfaces (3,6) having a focus (f1) corresponding to the light source (2), a first
parabolic group reflecting surface (7) with a focus on a second focus (f3) of the
second ellipse group reflecting surface (6), and a second parabolic group reflecting
surface (8) with a focus corresponding to the position of the light source (2). The
movable shutter (4) has a shutter part (4a) and a shade part (4b). When the shutter
part (4a) is placed in the light flux of the first ellipse group reflecting surface
(3), the shade part (4b) shades the light flux reaching from the light source (2)
to the second parabolic group reflecting surface (8). On the other hand, when the
shutter part (4a) is withdrawn from the light flux, the second parabolic group reflecting
surface (8) is allowed to receive light. Thus, the low-beam distribution and the high-beam
distribution can be improved in illumination. |
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a vehicle headlight, particularly to a vehicle headlight generally referred to as a projector-type headlight (Poly Ellipsoid Headlamp: PES) using an ellipse group reflecting surface (e.g., a spheroid reflecting surface), a projection lens with an aspheric surface, and a shutter for adjusting a light distribution characteristic, which is configured to be capable of switching between a meeting-beam (or low-beam) distribution and a running-beam (or high-beam) distribution.
2. Description of the Related Art
[0002] Referring now to Fig. 1, a projector-type headlight 90 typically used in the prior art will be described. The projector-type headlight 90 comprises a light source 91, an ellipse group reflecting surface 92, a shutter 93, and a projection lens 94. The ellipse group reflecting surface 92 is a reflecting surface configured as a spheroid, a complex ellipse, or the like, having a first focus f1 and a second focus f2. The light source 91 is arranged at a position corresponding to the first focus f1, while the shutter 93 is arranged at a position in the vicinity of the second focus f2 of the ellipse group reflecting surface 92. The focus of the projection lens 94 is arranged in the vicinity of the shutter 93. In the projector-type headlight 90 thus constructed, the movement of the shutter 93 allows a desired low-beam distribution pattern and a desired high-beam distribution pattern in a selective manner.
[0003] More specifically, as the vehicle headlight is constructed as described above, a light beam from the light source 91 is reflected by the ellipse group reflecting surface 92 and is then provided as reflection light having a generally circular cross section to be converged to the second focus. A lower half of the reflection light is shaded when the shutter 93 is placed in the optical path of the reflection light. Thus, the resulting reflected light has in general an upper semicircular part. The generally upper semicircular part of the reflected light is projected in the irradiation direction and turned upside down by the projection lens 94 to become a lower semicircular part of the reflected light. In other words, as shown in Fig. 2, the light distribution pattern HS suited for the low-beam distribution, which do not include a high beam, can be obtained.
[0004] On the other hand, the shutter 93 may be configured to be movable. If a high-beam distribution pattern is required, the shutter 93 can be withdrawn from the optical path of the light reflected from the reflecting surface 92. Thus, the lower semicircular part of the reflected light, which is to become a high beam and which is shaded by the shutter 93 in low-beam mode, is allowed to be projected as irradiation light, resulting in a high-beam distribution pattern HM as shown in Fig. 3.
[0005] In the conventional projector-type headlight 90, however, the lower half of the reflected light from the ellipse group reflecting surface 92 is shaded at the time of low-beam distribution. As a result, the amount of light to be provided for the low-beam distribution can be significantly poor in supply. To solve such a disadvantage, in general, an insufficient amount of the light is compensated by, for example, inclining the optical axis of the headlight to the lower left side when it is for driving on the left-hand side (In Japan, automotive vehicles drive on the left side) such that the portion corresponding to the point P that allows a high degree of brightness cannot be shaded by the shutter 93 (see Fig. 8).
[0006] On the other hand, if the shutter 93 is withdrawn from the above configuration of the headlight provided for obtaining the low-beam distribution, there is not enough irradiation light beam directing to the front (see Fig. 3). Therefore, there is another problem regarding insufficient visibility to a considerable distance with respect to the high-beam distribution.
[0007] In the projector-type headlight 90, generally, there is a further problem relating to poor visibilities in both left and right directions because of a slight lack of the width of irradiation light in these directions.
[0008] To solve the above problems with respect to an insufficient amount of light and visibilities in the above directions, the present inventors have developed vehicle headlights described in Japanese Patent Application Nos. 2000-392979, 2001-190196, and so on. In other words, they have made attempts to solve the above problems by reflecting the light conventionally unused from a plurality of reflective mirrors. In spite of these technologies, the illumination intensity and visibility are still insufficient, especially at a high-beam distribution.
SUMMARY OF THE INVENTION
[0009] In order to solve the above problems, therefore, it is an object of the present invention to provide a projector-type vehicle headlight by which a low-beam distribution and a high-beam distribution can be selectively employed and unused light can be effectively used as reflection light in each of the low- and high-beam distributions, and especially headlight, which is capable of attaining a sufficient illumination in the high-beam distribution.
[0010] Furthermore, it is another object of the present invention to provide a headlight capable of improving the visibility by applying a sufficient illumination in both left and right directions at the time of the high-beam distribution.
[0011] In order to attain the objects, a vehicle headlight according to the present invention includes:
a light source;
a first ellipse group reflecting surface having an optical axis substantially corresponding to an irradiation direction of a headlight, the first ellipse group reflecting surface having a first focus and a second focus, the first focus being located on a position of the light source, the first ellipse group reflecting surface reflecting light irradiated from the light source in the irradiation direction of the headlight;
a projection lens having a focus in the irradiation direction of the headlight and in the vicinity of the second focus of the first ellipse group reflecting surface, the projection lens projecting light irradiated from the light source and light reflected from the first ellipse group reflecting surface in the irradiation direction;
a second ellipse group reflecting surface having an optical axis crossing the optical axis of the first ellipse group reflecting surface, the second ellipse group reflecting surface having a first focus and a second focus, the first focus of the second ellipse group reflecting surface corresponding to a position of the light source;
a first parabolic group reflecting surface having a focus on a position of the second focus of the second ellipse group reflecting surface, the first parabolic group reflecting surface reflecting light reflected from the second ellipse group reflecting surface in the irradiation direction of the headlight;
a second parabolic group reflecting surface having an optical axis substantially corresponding to the irradiation direction of the headlight, the second parabolic group reflecting surface having a focus corresponding to a position in the vicinity of the light source, the second parabolic group reflecting surface being arranged in the irradiation direction side from the first ellipse group reflecting surface; and
a movable shutter provided in the vicinity of the focus of the projection lens, the movable shutter being capable of being placed in and withdrawn from an optical path of light reflected from the first ellipse group reflecting surface, the movable shutter having a shutter part and a shade part, the shutter part providing projection light from the projection lens with a low-beam distribution pattern by being placed in the optical path of the reflected light from the first ellipse group reflecting surface, the shutter part providing projection light from the projection lens with a high-beam distribution pattern by being withdrawn from the optical path, the shade part shading light reaching from the light source to the second parabolic group reflecting surface at the time of being placed in and providing light reaching from the light source to the second parabolic group reflecting surface at the time of being withdrawn.
[0012] From the above configuration of the vehicle headlight, at first, when the headlight is in the low-beam distribution which is normally used, unused light of the first ellipse group reflecting surface is captured on the second ellipse group reflecting surface, followed by projecting the captured light from the first parabolic group reflecting surface toward the irradiation direction to allow the headlight to be more illuminated in the low-beam distribution. Therefore, there is an extremely superior effect in improvement of visibility in the low-beam distribution.
[0013] Secondary, the high-beam distribution pattern is constructed such that it can be compensated with light being irradiated like a spot illumination in the front direction by the second parabolic group reflecting surface. In the prior art, on the other hand, such a high-beam distribution pattern is insufficient characteristic because of being inclined to the lower left side for increasing the visibility in the low-beam distribution. It is also configured such that the distribution of light from the first parabolic group reflecting surface is added on the high-beam distribution pattern. Consequently, an extremely superior effect in improvement of visibility at each of the low- and high-beam distributions can be attained. In addition to the above, the sufficient illuminations can be provided in the left and right directions.
[0014] In the vehicle headlight according to the present invention having such a constitution above, it is preferable to arrange the first ellipse group reflecting surface and the second ellipse group reflecting surface such that the second focus of the first ellipse group reflecting surface is on the outside of the second ellipse group reflecting surface. Also, it is preferable to locate the shutter part of the movable shutter on a back side of the second ellipse group reflecting surface when the shutter part is withdrawn from the optical path of the reflected light from the first ellipse group reflecting surface.
[0015] In one of preferred embodiments, the movable shutter may be rotatably fixed on a substantial horizontal axis to be placed in or be withdrawn from the optical path.
[0016] It is preferred that the second parabolic group reflecting surface is composed of a pair of reflecting surfaces provided on left and right sides of the first ellipse group reflecting surface in the horizontal direction such that the second parabolic group reflecting surface receives direct light from the light source when the movable shutter is withdrawn.
[0017] Preferably, the vehicle headlight according to the present invention further comprises shading means for shading the light reflected from the second ellipse group reflecting surface to the first parabolic group reflecting surface when a high-beam distribution is achieved. The shading means may be driven independently of the movable shutter. Alternatively, the shading means may be interlocked with the movable shutter. The shading means and the movable shutter may be rotated around a substantial horizontal axis.
[0018] In the vehicle headlight according to the present invention having such a constitution, the second ellipse group reflecting surface may preferably have an opening portion coinciding with a part of a light path of irradiation light from the light source and reflected light from the first ellipse group reflecting surface to the projection lens. In this case, the movable shutter can shade a part of the opening portion when it is placed in the optical path and open the opening portion when it is withdrawn from the optical path.
[0019] Further, in the vehicle headlight with the aforementioned constitution, the optical axis of the first parabolic group reflecting surface generally may preferably correspond to the irradiation direction of the headlight.
[0020] In the vehicle headlight in accordance with the above construction, it is preferable to set the optical axis of the first parabolic group reflecting surface such that the reflected light from the first parabolic group reflecting surface irradiates outwardly on a side of the irradiated area of the reflected light from the first ellipse group reflecting surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] These and other objects and advantages of the present invention will become clear from the following description with reference to the accompanying drawings, wherein:
Fig. 1 is a cross sectional view illustrating a conventional headlight;
Fig. 2 is an explanatory view showing a low-beam distribution pattern of the conventional headlight;
Fig. 3 is an explanatory view showing a high-beam distribution pattern of the conventional headlight;
Fig. 4 is a perspective view of a vehicle headlight in accordance with preferred embodiments of the present invention;
Fig. 5 is a cross sectional view taken along the line A-A in Fig. 4;
Fig. 6 is a cross sectional view taken along the line B-B in Fig. 4;
Fig. 7 is an explanatory view showing a low-beam distribution pattern of the vehicle headlight according to the present invention;
Fig. 8 is an explanatory view showing a high-beam distribution pattern of the vehicle headlight according to the present invention; and
Fig. 9 is an explanatory view showing a high-beam distribution pattern of a vehicle headlight in accordance with a another preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] Hereinafter, vehicle headlights according to the present invention will be described based on preferred embodiments with reference to the accompanying drawings.
[0023] In the present specification, the term "ellipse group reflecting surface" can be defined as a curved surface having an ellipse or a similar shape as a whole, such as a rotated elliptic surface (spheroid), a complex elliptic surface, an ellipsoidal surface, an elliptic cylindrical surface, an elliptical free-curved surface, or combination thereof. If a light source is located on a first focus of the ellipse group reflecting surface, light rays emitted from the light source converge to a second focus of the ellipse group reflecting surface.
[0024] The term "parabolic group reflecting surface" can be defined as a curved surface having a parabola or similar shape as a whole, such as a rotated parabolic surface, a complex parabolic surface, a paraboloidal surface, a parabolic free-curved surface, or combinations thereof. Light rays emitted from a light source located on a focus of the parabolic group reflecting surface are reflected to be parallel to the axis of the parabolic group reflecting surface.
[0025] Referring now to Figs. 4 to 6, there is shown a vehicle headlight denoted by reference numeral 1 as one of preferred embodiments of the present invention. The vehicle headlight 1 comprises a light source 2, a first ellipse group reflecting surface 3, a movable shutter 4, and a projection lens 5. The first ellipse group reflecting surface 3 is constructed of a spheroid surface, a complex ellipse surface, or the like and is a reflecting surface having an optical axis (axis of lens) X substantially corresponding to the direction of irradiating light from the vehicle headlight 1. The reflecting surface 3 has a first focus f1 and a second focus f2. The light source 2 is substantially arranged on the first focus f1. The movable shutter 4 is arranged in the vicinity of the second focus f2 of the projection lens 5 and is responsible for shading a part of reflected light from the first ellipse group reflecting surface 3 to provide the low-beam distribution pattern. Accordingly, such a configuration of the headlight 1 is similar to that of the conventional example described above in that it is capable of irradiating light with a low-beam distribution when the vehicle runs on an urban road in the night.
[0026] In the present invention, in contrast to the conventional one, a second ellipse group reflecting surface 6, a first parabolic group reflecting surface 7, and a second parabolic group reflecting surface 8 are additionally provided for solving the above problems in addition to the first ellipse group reflecting surface 3. In other words, the present invention solves the above problems of: an insufficient amount of light in each of low- and high-beam distributions; and the characteristic of high-beam distribution which becomes insufficient if the movable shutter 4 is merely withdrawn from an optical path of the reflected light from the first ellipse group reflecting source 3.
[0027] First, the second ellipse group reflecting surface 6 and the first parabolic group reflecting surface 7 will be described. These two reflecting surfaces 6 and 7 are provided for supplementing the amount of light appropriate for both the low- and high-beam distributions. As shown in Figs. 4 and 5, the second ellipse group reflecting surface 6 is one such as a spheroid surface or the like in which the light source 2 is arranged on a position corresponding to the first focus f1 (the position shared between the first focus of the first ellipse group reflecting surface 3 and the first focus f1) The optical axis Y of the reflecting surface 6 is set such that the second focus f3 of the reflecting surface 6 on the optical axis Y is located diagonally forward of the first focus f1 in a downward direction and located to intersect the optical axis X of the first ellipse group reflecting surface 3.
[0028] The second ellipse group reflecting surface 6 is arranged at a position that does not interfere with an optical path from the light source 2 to the first ellipse group reflecting surface 3 and with an optical path of reflected light from the first ellipse group reflecting surface 3. More specifically, the reflecting surface 6 is located forward of the first ellipse group reflecting surface 3 and is provided such that a mirror surface (the actual reflecting surface) is directed to the light source 2 for receiving light directly irradiated from the light source 2. If necessary, furthermore, there is formed an opening portion 6a through which reflected light from the first ellipse group reflecting surface 3 can be passed.
The opening portion 6a is configured such that a part of the opening portion 6a is shaded when the movable shutter 4 moves into the optical path, and that the opening portion 6a is completely opened when the movable shutter 4 is withdrawn from the optical path.
[0029] In the present invention, additionally, the second ellipse group reflecting surface 6 is configured so as to be located nearer the light source 2 than the second focus f2 of the first ellipse group reflecting surface 3. Therefore, the movable shutter 4 to be provided in the vicinity of the second focus f2 is located on the back side of the second ellipse group reflecting surface 6, so that there is no possibility of interfering with the second ellipse group reflecting surface 6.
[0030] The headlight of the present embodiment is constructed as described above. Therefore, the second ellipse group reflecting surface 6 is capable of capturing the light from the light source 2 which cannot be captured by the first ellipse group reflecting surface 3 in the configuration of the conventional headlight, allowing the convergence of light to the second focus f3 of the reflecting surface 6. In this embodiment, furthermore, there is provided the first parabolic group reflecting surface 7 for forwarding the resulting light in the irradiation direction of the headlight.
[0031] The first parabolic group reflecting surface 7 is formed as a parabolic shaped reflecting surface such as a paraboloid of revolution. The optical axis of the reflecting surface 7 substantially corresponds to the direction of irradiating light from the vehicle headlight 1. In addition, the focus of the reflecting surface 7 substantially corresponds to the second focus f3 of the second ellipse group reflecting surface 6. Therefore, the light captured and reflected by the second ellipse group reflecting surface 6 can be reflected by the first parabolic group reflecting surface 7 substantially in the direction of irradiating light from the vehicle headlight 1 as parallel light.
[0032] As shown in Figs. 4 and 6, the second parabolic group reflecting surface 8 is provided as a pair of reflecting surfaces on each of left and right sides of the first ellipse group reflecting surface 3 in the horizontal direction. The arrangement of the individual second parabolic group reflecting surfaces 8 on the left and on the right side of the optical axis X, respectively, when seen from the above and along the irradiation direction of the headlight is in the following also referred to as "being arranged in the irradiation direction side from the first ellipse group reflecting surface 3". In a another preferred embodiment the second parabolic group reflecting surface 8 comprises only one reflecting surface, which is located at either the left side or the right side of the optical axis. This arrangement is also covered by the expression "to be arranged in the irradiation direction side from the first ellipse group reflecting surface 3". The optical axis of the second parabolic group reflecting surface 8 substantially corresponds to the direction of irradiating light from the vehicle headlight 1. The focus of the reflecting surface 8 corresponds to the position of the light source 2. If the reflecting surface 8 is provided on the above position, it should be provided without causing any interference problem such as an overlap with the second ellipse group reflecting surface 6.
[0033] In the above configuration of the headlight, a low-beam distribution pattern can be attained by shading a high beam (upwardly directing light) by placing the movable shutter 4 in the flux of reflected light from the first ellipse group reflecting surface 3. If a high-beam distribution pattern is required, the movable shutter 4 is withdrawn from the flux of reflected light from the first ellipse group reflecting surface 3. In the present invention, the movable shutter 4 includes a shutter part 4a to be placed in or withdrawn from the light flux from the first ellipse group reflecting surface 3 and a shade part 4b to be placed in or withdrawn from the light flux directly transmitted from the light source 2 to the second parabolic group reflecting surface 8. In Fig. 4, the upper end of the shutter part 4a is shaped like a straight line. However, the present invention is not limited thereto, and if desired, the upper end of the shutter part 4a may be shaped into one of various cut lines depending on the desired light distribution pattern. Further, a connecting portion which connects the shutter part 4a and the shade part 4b may include a fold as shown in Fig. 6, although the fold is not shown in fig 4 for easy understanding. However, the fold is not necessarily be included in the movable shutter4, and the connecting portion which connects the shutter part 4a and the shade part 4b may be a straight line in the B-B cross section of fig. 4.
[0034] The movable shutter 4 is rotatably fixed on a horizontal axis 4c and is able to be rotated about the horizontal axis 4c by a driving force exerted from a driving part 4d such as solenoid. In the movable shutter 4, furthermore, a return spring 4e and a stopper 4f are arranged on appropriate positions, respectively. If the movable shutter 4 is not actuated by the driving part 4d, the movable shutter 4 is stopped at a predetermined position by means of the return spring 4e and the stopper 4f. In this case, therefore, the movable shutter 4 is not rotated, so that a low-beam distribution pattern can be obtained in a state that the movable shutter 4 is located at the predetermined stopped position.
[0035] Specifically, in a state that the movable shutter 4 is not actuated by the driving part 4d, the shutter part 4a moves into the light flux from the first ellipse group reflecting surface 3 to shade a high beam (upwardly directing light rays). Simultaneously, the shade portion 4b shades the light from the light source 2 to the second parabolic group reflecting surface 8.
[0036] If the driving part 4d is actuated, the shutter part 4a is rotated and withdrawn from the light flux from the first ellipse group reflecting surface 3 while the shade part 4b is withdrawn from the optical path directing from the light source 2 to the second parabolic group reflecting surface 8. Consequently, the light from the light source 2 can directly reach to the second parabolic group reflecting surface 8. Note that it is not restricted to obtain either of a low-beam distribution pattern or a high-beam distribution pattern when the driving part 4d is being actuated. In nature, however, when a vehicle is moving, the low-beam distribution pattern is predominantly selected because the setting to low-beam distribution at the time of stopping the driving part 4d is advantageous, compared with the setting to high-beam distribution, in terms of reduction in electric power consumption.
[0037] Next, the operation and effect of the vehicle headlight of the present embodiment as constructed above will be described. In Fig. 7, there is shown a low-beam distribution pattern DS of the vehicle headlight 1. In the low-beam distribution, almost a half of the reflected light from the first ellipse group reflecting surface 3 is shaded by the movable shutter 4 (the shutter part 4a). In this state, however, the low-beam distribution pattern DS is the sum of a distribution pattern DS1 from the first ellipse group reflecting surface 3 and a distribution pattern DS2 from the second ellipse group reflecting surface 6 and the first parabolic group reflecting surface 7 which capture light which has been never used in the prior art. Therefore, the low-beam distribution pattern DS which can be commonly used can be more lighted or can be illuminated to a greater extend. Furthermore, the point P in the figure is one where the maximum brightness in each of the distribution patterns can be obtained. In the figure, DS1' indicates a high illumination zone of the distribution pattern DS1 from the first ellipse group reflecting surface 3. Considering that half of the reflected light from the first ellipse group reflecting surface 3 is shaded by the shutter part 4a, the first ellipse group reflecting surface 3 is designed such that the maximum brightness point P is located at a position on the left or right side slightly lower than the origin (the front, H=0, V=0) (e.g., the left side if the vehicle runs on the left-hand side). In this embodiment, for example, the optical axis of the first ellipse group reflecting surface 3 is inclined to the lower left side.
[0038] On the other hand, in the state of the high-beam distribution pattern DM shown in Fig. 8, the movable shutter 4 (the shutter part 4a) is withdrawn from the flux of reflected light from the first ellipse group reflecting surface 3. Therefore, the distribution pattern DM1 can be obtained, in which the reflected light from the reflecting surface 3 includes a high beam i.e., upwardly directed light (lower part of the light in the vicinity of the focus of the projection lens), while irradiation light projected from the projection lens includes a high beam. However, as the optical axis of the first ellipse group reflecting surface 3 is inclined to the lower left side (if the vehicle runs on the left-hand side), the use of the distribution pattern DM1 alone is insufficient to irradiate the front at a considerable distance, without completely satisfying the functions of the high-beam distribution as described above. In the figure, by the way, the border line of the pattern DM1 is only indicated by a single contour line of a low illumination zone.
[0039] In this invention, the reflected light from the second parabolic group reflecting surface 8 is adjusted so as to be directed to in the vicinity of the origin (the front, H=0, V=0) to obtain the distribution pattern DM2.
As a result, a high-beam distribution pattern DM can be obtained as the sum of the distribution pattern DM1, the distribution pattern DM2, and the distribution pattern DS2 from the first parabolic group reflecting surface 7. This is irradiation light for irradiating the front at a considerable distance, satisfying the functions of high-beam distribution.
[0040] In Fig. 8, there is shown a high illumination zone DM3 of the high-beam distribution pattern DM. The high illumination zone DM3 is composed of a high illumination zone DM1' of the distribution pattern DM1 (i.e., one in the state where the distribution pattern DS1' is not shaded by the shutter part 4a as shown in Fig. 7) and the distribution pattern DM2 from the second parabolic group reflecting surface 8. The maximum brightness point P of the high-beam distribution pattern DM is located on the origin (the front, H=0, V=0), resulting in an extremely considerable distance visibility. Note that the zone DM3 is defined by a single contour line in the high illumination zone obtained by synthetically preparing the zone DM1' and the pattern DM2. The border line of the zone DM3 and the border line of the zone DM1' are not limited all in the same intensity of illumination.
[0041] Since the second parabolic group reflecting surface 8 is provided on each of left and right sides of the first ellipse group reflecting surface 3 in the horizontal direction, the reflected light from the second parabolic group reflecting surface 8 becomes one extending wide in the horizontal direction while extending narrow in the vertical direction when the light source 2 is long in the axial direction (e.g., C-8 filament). Therefore, the headlight is not able to irradiate the road surface nearer from the vehicle brightly more than necessary.
[0042] In this embodiment, the light being reflected by the second ellipse group reflecting surface 6 and the first parabolic group reflecting surface 7 (i.e., a portion corresponding to the distribution pattern DS2 of the low-beam distribution pattern DS) is remained as it is, even though it is in the high-beam distribution being switched. Therefore, the road surface just in front of the vehicle can be irradiated brightly. Thus, it becomes possible to provide a wide distribution pattern of light with a high intensity of illumination. On the other hand, however, the pupils of a driver, who watches closely high illuminated areas in close proximity to the car, might thus narrow. As a result, it is conceived that the long sight, i.e. the visibility to a considerable distance, may be deteriorated.
[0043] In this case, when the movable shutter 4 is located on the position where a high-beam distribution pattern can be obtained, a second shade part 4g (see Fig. 5) as shading means may be provided in accordance with a further embodiment of the present invention such that it can be inserted in the vicinity of the second focus f3 of the second ellipse group reflecting surface 6, for example. According to such a configuration of the headlight, when it is switched to provide the high-beam distribution pattern DM, as shown in Fig. 9, the reflected light from the first parabolic group reflecting surface 7 may be shaded. The second shade part 4g may be integrally formed with the movable shutter 4. Alternatively, the second shade part 4g and the movable shutter 4 may be separately formed. They may be driven independently of each other or may be interlocked with each other. Furthermore, if the second shade part 4g and the movable shutter 4 are integrally formed so as to actuate the same driving part 4d, several advantages can be obtained with respect to reduction in the number of structural components and the simplified structure of the headlight. If the second shade part 4g and the movable shutter 4 are separately obtained, different desired distribution patterns can be obtained at the time of high-beam distribution.
[0044] As another embodiment of the present invention, though not shown in the figure, the position of the second ellipse group reflecting surface 6 is not limited to be placed in a slanting upper direction of the first ellipse group reflecting surface 3, and it may be in a slanting lower direction or the like. Furthermore, the optical axis of the first parabolic group reflecting surface 7 is not limited to be in the direction X of irradiating light from the vehicle headlight 1, and it may be in the diagonally lateral direction, the lateral direction, or the like. By setting the reflecting surface in such a direction, for example, a distribution pattern of light can be obtained such that the distribution pattern DS2 is located on the outside of the distribution patterns DS1 and DM1. The second parabolic group reflecting surface 8 is not limited to be provided as a pair of reflecting surfaces to be arranged on the opposite lateral sides of the headlight, and it may be arranged only on one side thereof. Furthermore, the headlight can be configured for the purpose of obtaining a desired distribution pattern as a whole by the headlights being arranged on both left and right sides of the vehicle. Furthermore, though not shown in the drawings, the first ellipse group reflecting surface 3 and the first parabolic group reflecting surface 7 can be formed as a continuous surface. Further, the first ellipse group reflecting surface 3 and the second parabolic group reflecting surface 8 can be formed as a continuous surface depending on locations of the solenoid 4d, the spring 4e, and the stopper 4f.
[0045] While there has been described what are at present considered to be preferred embodiments of the present invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claims cover all such modifications as fall within the true spirit and scope of the invention.
a light source (2);
a first ellipse group reflecting surface (3) having an optical axis (X) substantially corresponding to an irradiation direction of a headlight (1), the first ellipse group reflecting surface (3) having a first focus (f1) and a second focus (f2), the first focus (f1) being located on a position of the light source (2), the first ellipse group reflecting surface (3) reflecting light irradiated from the light source (2) in the irradiation direction of the headlight (1);
a projection lens (5) having a focus in the irradiation direction of the headlight (1) and in the vicinity of the second focus (f2) of the first ellipse group reflecting surface (3), the projection lens (5) projecting light irradiated from the light source (2) and light reflected from the first ellipse group reflecting surface (3) in the irradiation direction;
a second ellipse group reflecting surface (6) having an optical axis (Y) crossing the optical axis (X) of the first ellipse group reflecting surface (3), the second ellipse group reflecting surface (6) having a first focus (f1) and a second focus (f3), the first focus (f1) of the second ellipse group reflecting surface corresponding to a position of the light source (2);
a first parabolic group reflecting surface (7) having a focus on a position of the second focus (f3) of the second ellipse group reflecting surface (6), the first parabolic group reflecting surface (7) reflecting light reflected from the second ellipse group reflecting surface (6) in the irradiation direction of the headlight (1);
a second parabolic group reflecting surface (8) having an optical axis substantially corresponding to the irradiation direction of the headlight (1), the second parabolic group reflecting surface (8) having a focus corresponding to a position in the vicinity of the light source, the second parabolic group reflecting surface (8) being arranged in the irradiation direction side from the first ellipse group reflecting surface (3); and
a movable shutter (4) provided in the vicinity of the focus of the projection lens (5), the movable shutter (4) being capable of being placed in and withdrawn from an optical path of light reflected from the first ellipse group reflecting surface (3), the movable shutter (4) having a shutter part (4a) and a shade part (4b), the shutter part (4a) providing projection light from the projection lens (5) with a low-beam distribution pattern by being placed in the optical path of the reflected light from the first ellipse group reflecting surface (3), the shutter part (4a) providing projection light from the projection lens (5) with a high-beam distribution pattern by being withdrawn from the optical path, the shade part (4b) shading light reaching from the light source (2) to the second parabolic group reflecting surface (8) at the time of being placed in and providing light reaching from the light source (2) to the second parabolic group reflecting surface (8) at the time of being withdrawn.
the first ellipse group reflecting surface (3) and the second ellipse group reflecting surface (6) are arranged such that the second focus (f2) of the first ellipse group reflecting surface (3) is on the outside of the second ellipse group reflecting surface (6), and
the shutter part (4a) of the movable shutter (4) is located on a back side of the second ellipse group reflecting surface (6) when the shutter part (4a) is withdrawn from the optical path of the reflected light from the first ellipse group reflecting surface (3).
the movable shutter (4) is rotatably fixed on a substantial horizontal axis (4c) to be placed in or be withdrawn from the optical path.
the second parabolic group reflecting surface (8) is composed of a pair of reflecting surfaces (8, 8) provided on left and right sides of the first ellipse group reflecting surface (3) in the horizontal direction such that the second parabolic group reflecting surface (8) receives direct light from the light source (2) when the movable shutter (4) is withdrawn.
the shading means (4g) is driven independently of the movable shutter (4).
the shading means (4g) is interlocked with the movable shutter (4).
the shading means (4g) and the movable shutter (4) are rotated around a substantial horizontal axis (4c).
the second ellipse group reflecting surface (6) has an opening portion (6a) coinciding with a part of a light path of irradiation light from the light source (2) and reflected light from the first ellipse group reflecting surface (3) to the projection lens (5).
the movable shutter (4) shades a part of the opening portion (6a) when it (4) is placed in the optical path and opens the opening portion (6a) when it (4) is withdrawn from the optical path.
the optical axis of the first parabolic group reflecting surface (7) substantially corresponds to the irradiation direction of the headlight (1).
the optical axis of the first parabolic group reflecting surface (7) is set such that the light reflected from the first parabolic group reflecting surface (7) irradiates outwardly on a side of the irradiated area of the reflected light from the first ellipse group reflecting surface (3).
a light source (2);
a first ellipse group reflecting surface (3) reflecting light emitted from the light source (2) in the irradiation direction of the headlight (1);
a second ellipse group reflecting surface (6) reflecting light from the light source (2),
a first parabolic group reflecting surface (7) receiving the reflected light from the second ellipse group reflecting surface (6) and reflecting it in turn into the irradiation direction of the headlight (1);
a second parabolic group reflecting surface (8) reflecting light from the light source (2); and
a movable shutter (4) having a shutter part (4a) and a shade part (4b), the shutter part (4a) providing for a low-beam distribution pattern by being placed in the optical path of the reflected light from the first ellipse group reflecting surface (3)and for providing a high-beam distribution pattern by being withdrawn from the optical path, the shade part (4b) selectively shading light travelling from the light source (2) to the second parabolic group reflecting surface (8).