Vehicle headlamp

Abstract

 A vehicle lighting unit capable of achieving a plurality of functions of lamps such as a low-beam headlamp and a daytime running lamp at the same time is provided. The vehicle lighting unit (10) can include: a projection lens (11) disposed on an optical axis (AX) extending along a front-to-rear direction of a vehicle and having a rear focal point (F₁₁); a first lamp constituent member (12, 13, 14) to constitute a first lamp together with the projection lens (11); and a second lamp constituent member (15, 16) to constitute a second lamp together with the projection lens (11). The first lamp constituent member (12, 13, 14) can include: a first semiconductor light emitting device (12) disposed on or near the optical axis (AX) and behind the rear focal point (F₁₁) of the projection lens (11) so as to emit light substantially upward; a first reflecting surface (13) of a revolved ellipsoid having a first focal point (F1₁₃) set at or near the first semiconductor light emitting device (12) and a second focal point (F2₁₃) at or near the rear focal point (F₁₁) of the projection lens (11), the first reflecting surface (13) being disposed above the first semiconductor light emitting device (12) so that light emitted from the first semiconductor light emitting device (12) can be incident thereon; and a first light-shielding member (14) disposed in between the projection lens (11) and the first semiconductor light emitting device (12) so as to shield part of light emitted from the first semiconductor light emitting device (12). The second lamp constituent member (15, 16) can include: a second semiconductor light emitting device (15) disposed in a space (S) between the first light-shielding member (14) and a light path of light from the first semiconductor light emitting device (12) to pass through the projection lens (11), so as not to shield light passing through the projection lens (11), the second semiconductor light emitting device (15) being disposed so as to emit light substantially upward; and a second reflecting surface (16) disposed in the space (S) and above the second semiconductor light emitting device (15) so as to receive the light emitted from the second semiconductor light emitting device (15) and reflect the light toward the projection lens (11) to allow the light to pass through the projection lens (11) forward.

Description

Technical Field

[0001] The present invention relates to a vehicle lighting unit, and in particular to a vehicle lighting unit capable of achieving a plurality of functions of lamps such as a low-beam headlamp and a daytime running lamp.

Background Art

[0002] In the technical field of a conventional vehicle lighting, a vehicle lamp 200 as shown in Fig. 7 has been known which includes a low-beam headlamp A, a daytime running lamp T for notifying the presence of a vehicle in the front area during daytime, and the like lamps. (See Bosch Automotive Handbook (7th edition), p. 968.)

[0003] The vehicle lamp 200 described in Bosch Automotive Handbook has a configuration wherein separate lamps having respective different functions, such as a low-beam headlamp A and a daytime running lamp T, should be arranged at different positions in the front portion of a vehicle body (see Fig. 7). Due to the configuration as shown in the drawing, it is difficult to arrange the separate lamps, such as a low-beam headlamp A and a daytime running lamp T, having respective different functions within a limited area.

Summary

[0004] The present invention was devised in view of these and other problems and features in association with the conventional art. According to an aspect of the present invention, there is provided a vehicle lighting unit capable of achieving a plurality of functions of lamps such as a low-beam headlamp and a daytime running lamp at the same time.

[0005] According to another aspect of the present invention, a vehicle lighting unit having an optical axis extending along a front-to-rear direction of a vehicle can include a projection lens disposed on the optical axis and having a rear focal point; a first lamp constituent member to constitute a first lamp together with the projection lens; and a second lamp constituent member to constitute a second lamp together with the projection lens. The first lamp constituent member can include: a first semiconductor light emitting device disposed on or near the optical axis and behind the rear focal point of the projection lens so as to emit light substantially upward; a first reflecting surface of a revolved ellipsoid having a first focal point set at or near the first semiconductor light emitting device and a second focal point at or near the rear focal point of the projection lens, the first reflecting surface being disposed above the first semiconductor light emitting device so that light emitted from the first semiconductor light emitting device can be incident thereon; and a first light-shielding member disposed in between the projection lens and the first semiconductor light emitting device so as to shield part of light emitted from the first semiconductor light emitting device. The second lamp constituent member can include: a second semiconductor light emitting device disposed in a space between the first light-shielding member and a light path of light from the first semiconductor light emitting device to pass through the projection lens so as not to shield light passing through the projection lens, the second semiconductor light emitting device being disposed so as to emit light substantially upward; and a second reflecting surface disposed in the space and above the second semiconductor light emitting device so as to receive the light emitted from the second semiconductor light emitting device and reflect the light toward the projection lens to allow the light to pass through the projection lens forward.

[0006] The vehicle lighting unit of this aspect can be configured such that the light emitted from the first semiconductor light emitting device can be incident on the first reflecting surface and be reflected off the same to be converged on or near the rear focal point of the projection lens, and then be diffused. Accordingly, the space between the light-shielding member and the optical path through which the light from the first semiconductor light emitting device can travel toward the projection lens is available to arrange the second lamp constituent member (including, for example, the second semiconductor light emitting device and the second reflecting surface) that can achieve another lamp function in addition to the main vehicle lamp function.

[0007] In other words, according to this aspect, the so-called dead space in a projector type vehicle lighting unit can be efficiently utilized for receiving the second lamp constituent member to achieve another lamp function. This means that there is no additional space required for such another lamp function within a vehicle body and no need to expand the entire size thereof at all. Accordingly, this single projector type vehicle lighting unit can provide different lamp functions, such as a low-beam headlamp and a daytime running lamp at the same time with the same size as that of the conventional lighting unit.

[0008] In the above-described vehicle lighting unit, the projection lens can have a daytime-running-lamp (DRL) dedicated lens surface at a portion of the projection lens where the light from the first reflecting surface does not pass through, and the DRL-dedicated lens surface is capable of diffusing the light from the second semiconductor light emitting device in vertical and horizontal directions.

[0009] Further, in the above-described vehicle lighting unit, the first lamp can function as a headlamp for forming a low-beam light distribution pattern. The second lamp can function as a lamp for forming a DRL light distribution pattern or a positioning lamp light distribution pattern.

Brief Description of Drawings

[0010] These and other characteristics, features, and advantages of the presently disclosed subject matter will become clear from the following description with reference to the accompanying drawings, wherein:

Fig. 1 is a vertical cross-sectional view cut along a vertical plane including the optical axis AX of a vehicle lighting unit 10 according to an exemplary embodiment;

Fig. 2A is a perspective view of a first semiconductor light emitting device 12, and Fig. 2B is a perspective view of a second semiconductor light emitting device 15;

Fig. 3 is a graph showing exemplary directional characteristics of the first semiconductor light emitting device 12;

Fig. 4 is a diagram showing an exemplary low-beam light distribution pattern P1;

Fig. 5 is a diagram showing an exemplary DRL (daytime running lamp) light distribution pattern P2;

Fig. 6 is a cross-sectional view of a modified example of a lens 11 for use in the vehicle lighting unit according to the present exemplary embodiment; and

Fig. 7 is a front view of a conventional vehicle lighting unit 200.

Description of Exemplary Embodiments

[0011] A description will now be made below to a vehicle lighting unit of the present invention with reference to the accompanying drawings in accordance with exemplary embodiments.

[0012] In the present specification, it should be noted that the upper (upward), lower (downward), left, right, back (rearward), and front (forward) directions are based on a typical posture of an automobile vehicle body to which the vehicle lighting unit is installed unless otherwise specified.

[0013] The vehicle lighting unit 10 of the present exemplary embodiment can be a combination type vehicle lighting unit functioning as a daytime running lamp (DRL) and a vehicle headlamp (also as a positioning lamp). The vehicle lighting unit 10 can be disposed at either front side of a vehicle body such as an automobile. The vehicle lighting unit 10 can be linked to a known aiming mechanism (not shown in the drawings) so that its optical axis can be adjusted.

[0014] Fig. 1 is a vertical cross-sectional view cut along a vertical plane including the optical axis AX of the vehicle lighting unit 10 according to the present exemplary embodiment.

[0015] As shown in Fig. 1, the vehicle lighting unit 10 having an optical axis AX extending in a front-to-rear direction of a vehicle body can include a projection lens 11 disposed on or near the optical axis AX and having a rear focal point F₁₁, a first semiconductor light emitting device 12 disposed on or near the optical axis AX and behind the rear focal point F₁₁ of the projection lens 11 so as to emit light substantially upward, a first reflecting surface 13 disposed above the first semiconductor light emitting device 12, a first light-shielding member or a first shade 14 disposed in between the projection lens 11 and the first semiconductor light emitting device 12 and secured to a heat sink 18 with a screw N so as to shield part of light emitted from the first semiconductor light emitting device 12 and reflected by the first reflecting surface 13, a second semiconductor light emitting device disposed in between the projection lens 11 and the shade 14, a second reflecting surface disposed above the second semiconductor light emitting device 15, a lens holder 17, the heat sink 18, and the like.

[0016] As shown in Fig. 1, the projection lens 11 can be held by the lens holder that may be integrally formed with the first shade 14, and disposed on or near the optical axis AX.

[0017] The projection lens can be a planar convex aspheric projection lens that is convex forward while having a flat rear surface. The projection lens 11 can be formed by injecting a transparent resin such as an acrylic resin and a polycarbonate resin and cooling the resin to solidify the resin. The projection lens 11 may be made of glass or the like material. The projection lens 11 can have a circular or ellipsoid shape when viewed from its front side. Also, the projection lens 11 may take a polygonal shape such as a rectangular shape or higher polygonal shape when viewed from its front side.

[0018] A description will next be given of the first lamp constituent member that constitutes the first lamp forming a low-beam light distribution pattern together with the projection lens 11. In the present embodiment, the first lamp can function as a headlamp by means of the projector type vehicle lighting unit.

[0019] The first lamp constituent member can include the first semiconductor light emitting device 12, the first reflecting surface 13, the first shade 14, and the like.

[0020] Fig. 2A is a perspective view of the first semiconductor light emitting device 12.

[0021] The first semiconductor light emitting device 12 can include a plurality of chip-type LEDs 12a, for example, four blue LEDs 12a with a 1mm-square shape. The LED chip of each LED 12a can be covered with a wavelength conversion material (layer), for example, a YAG phosphor being a yellow phosphor. The number of the LEDs 12a is not limited to four, but 1 to 3 or 5 or more LEDs may be used in accordance with the desired performances. The LEDs 12a can have a higher illuminance than LEDs 15a of the second semiconductor light emitting device 15 in order to form a desired low-beam light distribution pattern required to have a higher brightness than a DRL light distribution pattern.

[0022] The respective LEDs 12a can be mounted on a first substrate KA that can be secured on a top surface of the heat sink 18 so as to emit light upward or upward and slightly rearward as shown in Fig. 1. The first semiconductor light emitting device 12 can be disposed on or near the optical axis AX and behind the rear focal point F₁₁ of the projection lens 11. Further, the LEDs 12a can be arranged in a line with predetermined intervals while their one sides are set along a horizontal line perpendicular to the optical axis AX in the width direction of the vehicle lighting unit 10 (in Fig. 1, in a direction perpendicular to the plane of paper). In the illustrated exemplary embodiment, the LEDs 12a can be symmetric with respect to the optical axis AX as shown in Fig. 2A.

[0023] The first substrate KA can have a front edge KAa and a rear edge KAb that is disposed lower than the front edge KAa so that the first substrate KA is inclined with respect to a horizontal plane, as shown in Fig. 1, whereby the mounted LEDs 12a can be inclined rearward (namely, its optical axis AX_12a can be directed upward while inclined slightly rearward). Off course, the first substrate KA may be disposed such that the front edge KAa and the rear edge KAb are positioned at the same horizontal level.

[0024] The first semiconductor light emitting device 12 can be electrically connected to a not-shown lighting circuit via a power source cable C, whereby the first semiconductor light emitting device 12 can be controlled by being supplied with a constant current from the lighting circuit.

[0025] The heat generated from the first semiconductor light emitting device 12 can be dissipated through the heat sink 18.

[0026] Fig. 3 is a graph showing exemplary directional characteristics of the first semiconductor light emitting device 12 (LED 12a). It should be noted that the directivity characteristic of the second semiconductor light emitting device 15 (LED 15a) can be the same as that of the first semiconductor light emitting device 12.

[0027] The directional characteristics can represent the percentage of luminous intensity in various directions with respect to the optical axis AX_12a of the first semiconductor light emitting device 12 (LED 12a) when the luminous intensity in the optical axis AX_12a is assumed as 100%. It can represent the spread degree of light emitted from the first semiconductor light emitting device 12 (LED 12a). The term "half value angle" means the angle at which the percentage of luminous intensity is 50%, and the illustrated example shows the half value angle of ±60 degrees as shown in Fig. 3.

[0028] The first semiconductor light emitting device 12 may be a device light source including a light emitting. chip that can perform surface emission as a substantially point light source, and is not limited to a chip-type LED 12a. Examples of the first semiconductor light emitting device 12 other than the chip-type LED 12a may include a light emitting diode, a laser diode, and the like.

[0029] The first reflecting surface 13 shown in Fig. 1 can be a revolved ellipsoid or similar free curved surface having a first focal point F1₁₃ set at or near the first semiconductor light emitting device 12 and a second focal point F2₁₃ at or near the rear focal point F₁₁ of the projection lens 11.

[0030] The first reflecting surface 13 can extend from one side of the first semiconductor light emitting device 12 (from the vehicle rear side in FIG. 1) toward the projection lens 11 and cover the first semiconductor light emitting device 12 from above. The first reflecting surface 13 can be designed such that relatively high luminous intensity light emitted substantially upward from the first semiconductor light emitting device 12 in narrow angle directions with respect to the element optical axis AX_12a of the first semiconductor light emitting device 12 (for example, light within about the half value angles (namely, light within ±60 degrees in Fig. 3)) can be incident on the first reflecting surface 13. The light emitted from the first semiconductor light emitting device 12 and being incident on the first reflecting surface 13 can be reflected by the first reflecting surface 13 and converged at or near the rear focal point F₁₁ of the projection lens 11 so as to be projected forward through the projection lens 11.

[0031] The first shade 14 can have a mirror surface 14a extending from the position of the rear focal point F₁₁ of the projection lens 11 toward the first semiconductor light emitting device 12. The front edge of the first shade 14 can be curved along the rear focal point of the projection lens 11. Part of the light can be incident on the mirror surface 14a, reflected upward by the same to enter the projection lens 11, and refracted by the projection lens 11 to be directed to a road surface. In this manner, the part of the light being incident on the mirror surface 14a can be overlaid on the light distribution pattern below the cut-off line thereof.

[0032] The light emitted from the first semiconductor light emitting device 12 can be incident on the first reflecting surface 13 and be reflected off the same to be converged on or near the rear focal point F₁₁ of the projection lens 11, and then be diffused. Accordingly, a space S can be formed between the first shade 14 (and also the lens holder 17 formed integrally with the first shade 14) and the optical path through which the light from the first semiconductor light emitting device 12 can travel toward the projection lens 11 is available as shown in Fig. 1. Thereby, the second lamp constituent member (including, for example, the second semiconductor light emitting device 15 and the second reflecting surface 16) that can achieve another lamp function (in the illustrated exemplary embodiment, functioning as a daytime running lamp or positioning lamp) can be disposed in addition to the main vehicle lamp function.

[0033] A description will next be given of the second lamp constituent member that constitutes the second lamp forming a DRL light distribution pattern or a positioning lamp light distribution pattern together with the projection lens 11 (or part of the projection lens 11 below the optical axis AX). In the present embodiment, the second lamp can function as a daytime running lamp as well as a positioning map.

[0034] The second lamp constituent member can include the second semiconductor light emitting device 15, the second reflecting surface 16, and the like. The second semiconductor light emitting device 15 and the second reflecting surface 16 can be arranged within the space S so as not to block the light from the first reflecting surface 13 to the projection lens 11.

[0035] Fig. 2B is a perspective view of the second semiconductor light emitting device 15.

[0036] The second semiconductor light emitting device 15 can include a plurality of chip-type LEDs 15a, for example, four blue LEDs 15a with a 1mm-square shape. The LED chip of each LED 15a can be covered with a wavelength conversion material (layer), for example, a YAG phosphor being a yellow phosphor. The number of the LEDs 15a is not limited to four, but 1 to 3 or 5 or more LEDs may be used in accordance with the desired performances.

[0037] The respective LEDs 15a can be mounted on a second substrate KB that can be secured on an inner peripheral surface of the lens holder 17 so as to emit light upward or upward and slightly rearward as shown in Fig. 1. The second semiconductor light emitting device 15 can be disposed in between the projection lens 11 and the first shade 14. Further, the LEDs 15a can be arranged in a line with predetermined intervals while their one sides are set along a horizontal line perpendicular to the optical axis AX in the width direction of the vehicle lighting unit 10 (in Fig. 1, in a direction perpendicular to the plane of paper). In the illustrated exemplary embodiment, the LEDs 15a can be symmetric with respect to the optical axis AX as shown in Fig. 2B.

[0038] The second semiconductor light emitting device 15 may be a device light source including a light emitting chip that can perform surface emission as a substantially point light source, and is not limited to a chip-type LED 15a. Examples of the second semiconductor light emitting device 15 other than the chip-type LED 15a may include a light emitting diode, a laser diode, and the like.

[0039] The second reflecting surface 16 can extend from one side of the second semiconductor light emitting device 15 (from the vehicle rear side in FIG. 1) to the position near the element optical axis AX_15a forward and obliquely upward, and cover the second semiconductor light emitting device 15 from above. The second reflecting surface 16 can be designed such that relatively high luminous intensity light emitted substantially upward from the second semiconductor light emitting device 15 in narrow angle directions with respect to the element optical axis AX_15a of the second semiconductor light emitting device 15 (for example, light within about the half value angles (namely, light within ±60 degrees in Fig. 3)) can be incident on the second reflecting surface 16.

[0040] The second reflector 16 can be arranged within the space S while being inclined so that the light emitted from the second semiconductor light emitting device 15 can be reflected by the second reflecting surface 16 and projected forward through the projection lens 11. The inclination angle of the second reflecting surface 16 with respect to the horizontal plane can affect the vertical width of a light distribution pattern formed on a virtual vertical screen. Therefore, the inclination angle of the second reflecting surface 16 with respect to the horizontal plane can be so designed such that the light can be projected within the light distribution pattern as determined by the domestic law.

[0041] The second reflecting surface 16 can have a shape designed such that the light emitted from the second semiconductor light emitting device 15 and reflected by the second reflecting surface 16 can be projected and diffused in the vertical and horizontal directions conforming to the DRL light distribution pattern (vertical and horizontal widths) to be formed on the virtual vertical screen. The second reflecting surface 16 can be a curved surface that can be adjusted to control the diffusion in the vertical and horizontal directions.

[0042] The second reflecting surface 16 can be formed by injecting a thermosetting resin in a metal mold and cooling the resin to solidify the resin, and then subjecting the solidified resin to mirror treatment such as aluminum deposition. The second reflecting surface 16 may be a paraboloid-based reflecting surface including a plurality of small segmented reflecting surfaces (multi-reflector, not shown). Such small segmented reflecting surfaces can be adjusted in area, direction, and the like so as to reflect light toward the desired areas in the virtual vertical screen. In this manner, the DRL light distribution pattern can have a desired luminance distribution as well as a desired area in the vertical and horizontal directions (desired vertical and horizontal widths). If the second reflecting surface 16 is a paraboloid-based reflecting surface, it is preferable that the second semiconductor light emitting device 15 be disposed at or near the focal point of the second reflecting surface 16.

[0043] The second semiconductor light emitting device 15 can be electrically connected to a not-shown lighting circuit via a power source cable, whereby the second semiconductor light emitting device 15 can be controlled by being supplied with a constant current from the lighting circuit.

[0044] With this configuration as above, the light emitted from the second semiconductor light emitting device 15 and being incident on the second reflecting surface 16 can be reflected by the second reflecting surface and projected through the projection lens 11 forward.

[0045] A description will now be given of the exemplary operation of the vehicle lighting unit 10 with the above-described configuration.

[0046] When a low-beam operation is selected via a not-shown switch connected to the not-shown lighting circuit, the lighting circuit can supply the first semiconductor light emitting device 12 and the second semiconductor light emitting device 15 with a constant current I3 and a constant current I1, respectively. In this case, the constant current I1 for the low-beam operation can be smaller than a constant current I2 for a DRL operation. In this manner, the first semiconductor light emitting device 12 and the second semiconductor light emitting device 15 can be energized to emit light, with the second semiconductor light emitting device 15 emitting less amount of light than that during the DRL operation.

[0047] In this case, the light from the second semiconductor light emitting device 15 can take the same optical path as that during the DRL operation, which will be described later. With this configuration, the light can be spread vertically and horizontally to a certain degree, so that a light distribution pattern suitable for a positioning lamp light distribution pattern can be formed on a virtual vertical screen (disposed virtually about 25 m in front of a vehicle body).

[0048] On the other hand, the light from the first semiconductor light emitting device 12 can take the following optical path.

[0049] Specifically, the light emitted from the first semiconductor light emitting device 12 and being incident on the first reflecting surface 13 can be reflected by the first reflecting surface 13 and converged at or near the rear focal point F₁₁ of the projection lens 11 so as to be projected forward through the projection lens 11. Part of the light reflected by the first reflecting surface 13 can be incident on the mirror surface 14a, reflected upward by the same to enter the projection lens 11, and refracted by the projection lens 11 to be directed to a road surface. In this manner, the part of the light being incident on the mirror surface 14a can be overlaid on the light distribution pattern below the cut-off line thereof. With this configuration, the light can form a light distribution pattern P1 suitable for a low-beam light distribution pattern on the virtual vertical screen (disposed virtually about 25 m in front of a vehicle body), wherein the low-beam light distribution pattern can include a cut-off line CL at its upper edge defined by the first shade 14, as shown in Fig. 4.

[0050] When a DRL operation is selected via the not-shown switch connected to the not-shown lighting circuit, the lighting circuit can supply the second semiconductor light emitting device 15 with the constant current I2 larger than the constant current I1 for the low-beam operation. In this manner, the second semiconductor light emitting device 15 can be energized to emit light, with the first semiconductor light emitting device 15.

[0051] In this case, the light from the second semiconductor light emitting device 15 can take the following optical path.

[0052] Specifically, the light emitted from the second semiconductor light emitting device 15 and being incident on the second reflecting surface 16 can be reflected by the second reflecting surface 16 and projected forward through the projection lens 11. The light from the second semiconductor light emitting device 15 and passing through the projection lens 11 can be diffused by the action of the projection lens 11 (mainly by the lower part of the lens 11 below the optical axis AX) in the vertical and horizontal directions conforming to the DRL light distribution pattern (vertical and horizontal widths). The projection lens 11 can refract and diffuse the light from the second semiconductor light emitting device 15 and reflected by the second reflecting surface 16. This can be achieved by disposing the second semiconductor light emitting device 15 at a position shifted from the rear focal point F₁₁ of the projection lens 11. With this configuration, the light can form a second light distribution pattern P2 suitable for a DRL light distribution pattern on the virtual vertical screen (disposed virtually about 25 m in front of a vehicle body), wherein the DRL light distribution pattern can be spread horizontally above and below the horizontal line H-H as shown in Fig. 5 (for example, spread by ±10 degrees above and below with respect to the horizontal line H-H).

[0053] In another mode, the second reflecting surface 15 can be adjusted to control the degree of diffusion in the vertical and horizontal direction. Accordingly, the resulting light distribution pattern can be adopted to a DRL light distribution pattern for the European standard (spread by 10 degrees above and 5 degrees below with respect to the horizontal line H-H) and also to a DRL light distribution pattern for the U.S. standard (spread by ±5 degrees above and below with respect to the horizontal line H-H).

[0054] It should be noted that the vehicle lighting unit 10 can be linked to a known aiming mechanism (not shown in the drawings) so that its optical axis can be adjusted to illuminate a proper area on the virtual vertical screen with the respective light distribution patterns P1 and P2.

[0055] As described above, according to the vehicle lighting unit 10 of the present exemplary embodiment, the light emitted from the first semiconductor light emitting device 12 can be incident on the first reflecting surface 13 and be reflected off the same to be converged on or near the rear focal point F₁₁ of the projection lens 11, and then be diffused. Accordingly, the space S can be formed between the first shade 14 (and also the lens holder 17 formed integrally with the first shade 14) and the optical path through which the light from the first semiconductor light emitting device 12 can travel toward the projection lens 11 is available as shown in Fig. 1. Thereby, the second lamp constituent member (including, for example, the second semiconductor light emitting device 15 and the second reflecting surface 16) that can achieve another lamp function (in the illustrated exemplary embodiment, functioning as a daytime running lamp or positioning lamp) can be disposed in addition to the main vehicle lamp function.

[0056] In other words, according to this aspect, the so-called dead space S in a projector type vehicle lighting unit can be efficiently utilized for receiving the second lamp constituent member to achieve another lamp function. This means that there is no additional space required for such another lamp function and no need to expand the entire size thereof at all. Accordingly, this single projector type vehicle lighting unit can provide different lamp functions, such as a low-beam headlamp and a daytime running lamp at the same time with the same size as that of the conventional lighting unit.

[0057] A description will now be given of modified examples.

[0058] In the above-described exemplary embodiment, when a low-beam operation is selected, both the first and second semiconductor light emitting devices 12 and 15 are energized to emit light while the second semiconductor light emitting device 15 emits less amount of light than that during the DRL operation. However, the present invention is not limited to this exemplary embodiment. For example, when the low-beam operation is selected, only the first semiconductor light emitting device 12 can be energized to emit light while the second semiconductor light emitting device 15 is not energized.

[0059] In still another modified example, as shown in Fig. 6, the projection lens 11 can include a DRL-dedicated lens surface 11a formed at part of the lens 11. The DRL-dedicated lens surface 11a can be formed at a portion where the light from the first reflecting surface 13 does not pass through and can be a curved surface functioning as a surface for diffusion. The DRL-dedicated lens surface 11a can diffuse the light from the second semiconductor light emitting device 15 in the vertical and horizontal directions conforming to the DRL light distribution pattern (vertical and horizontal widths) to be formed on the virtual vertical screen. In this case, in order to cause parallel light to enter the DRL-dedicated lens surface 11a, it is desired that the second reflecting surface 16 be a paraboloidal reflecting surface and the second semiconductor light emitting device 15 be disposed on or near the focal point of the second reflecting surface 16.

Claims

1. A vehicle lighting unit (10) having an optical axis (AX) extending along a front-to-rear direction of a vehicle, the vehicle lighting unit (10) comprising:

a projection lens (11) disposed on the optical axis (AX) and having a rear focal point (F₁₁);

a first lamp constituent member (12, 13, 14) to constitute a first lamp together with the projection lens (11); and

a second lamp constituent member (15, 16) to constitute a second lamp together with the projection lens (11),

the first lamp constituent member (12, 13, 14) including:

a first semiconductor light emitting device (12) disposed on or near the optical axis (AX) and behind the rear focal point (F₁₁) of the projection lens (11) so as to emit light substantially upward;

a first reflecting surface (13) of a revolved ellipsoid having a first focal point (F1₁₃) set at or near the first semiconductor light emitting device (12) and a second focal point (F2₁₃) at or near the rear focal point (F₁₁) of the projection lens (11), the first reflecting surface (13) being disposed above the first semiconductor light emitting device (12) so that light emitted from the first semiconductor light emitting device (12) can be incident thereon; and

a first light-shielding member (14) disposed in between the projection lens (11) and the first semiconductor light emitting device (12) so as to shield part of light emitted from the first semiconductor light emitting device (12),

the second lamp constituent member (15, 16) including:

a second semiconductor light emitting device (15) disposed in a space (S) between the first light-shielding member (14) and a light path of light from the first semiconductor light emitting device (12) to pass through the projection lens (11), so as not to shield light passing through the projection lens (11), the second semiconductor light emitting device (15) being disposed so as to emit light substantially upward; and

a second reflecting surface (16) disposed in the space (S) and above the second semiconductor light emitting device (15) so as to receive the light emitted from the second semiconductor light emitting device (15) and reflect the light toward the projection lens (11) to allow the light to pass through the projection lens (11) forward.

2. The vehicle lighting unit (10) according to claim 1, wherein the projection lens (11) has a DRL-dedicated lens surface (11a) at a portion of the projection lens (11) where the light from the first reflecting surface (13) does not pass through, the DRL-dedicated lens surface (11a) being capable of diffusing the light from the second semiconductor light emitting device (15) in vertical and horizontal directions.

3. The vehicle lighting unit (10) according to claim 1 or 2, wherein the first lamp functions as a headlamp for forming a low-beam light distribution pattern.

4. The vehicle lighting unit (10) according to any one of claims 1 to 3, wherein the second lamp functions as a lamp for forming a DRL light distribution pattern or a positioning lamp light distribution pattern.

Drawing