1. Field of the Invention
The present invention relates to a vehicle lighting apparatus.
2. Related Art
A headlamp for use in a vehicle is structured such that a high beam light distribution serving as a light distribution suitable for use in a normal running of the vehicle and a low beam light distribution serving as a light distribution for preventing a dazzle with respect to a vehicle running ahead or an oncoming vehicle can be switched over to each other. As a headlamp capable of switching the high beam light distribution and low beam light distribution over to each other, there is proposed a headlamp of a type that switches two light sources over to each other to thereby switch two kinds of light distribution over to each other. For example, a headlamp disclosed in Patent Document 1 uses, as a light source device, a dual filament bulb including two filaments and, by switching light emission of the two filaments over to each other, switches the high beam and low beam light distribution over to each other. Also, the headlamp disclosed in the Patent Document 1 includes an elliptic reflector for obtaining desired light distribution and a vertical reflector having a curved shape near to the arc of a parabola, and reflects lights emitted from the two reflectors to thereby obtain suitable high beam light distribution and low beam light distribution.
In the headlamp disclosed in the Patent Document 1, the elliptic reflector performs an effective function on light emitted from one of the two filaments to obtain first light distribution, while the vertical reflector performs an effective function on light emitted from the other to obtain second light distribution. Therefore, when one of the filaments, for example, the other filament emits light, the light can be projected onto the elliptic reflector formed to reflect light from one filament and, consequently, in some cases, the light of the other filament reflected by the elliptic reflector can have an unfavorable influence on the second light distribution.
One or more embodiments provide a vehicle lighting apparatus which includes two light sources and can switch two kinds of light distribution over to each other and which also can shut off light undesirable for light distribution to thereby obtain suitable light distribution. In addition, one or more embodiments provide a vehicle lighting apparatus which reuses light to be shaded for obtaining necessary light distribution in the light distribution to thereby improve the light distribution and reduce the power consumption.
In accordance with one or more embodiments, a vehicle lighting apparatus may include: a light source device including a first light source and a second light source; a reflector adapted to reflect forwardly light emitted from the light sources; a main shade adapted to shade a portion of light emitted from the first light source and reflected by the reflector; and a sub shade adapted to shade at least a portion of light emitted from the second light source and reflected by the reflector.
The description of embodiments will be given below with reference to the drawings. Further, the embodiments are not intended to limit the invention but to serve as examples thereof, and all features or combinations thereof described in the embodiments are not always essential to the invention.
The bulb 1 formed as the light source device of the lamp unit LU is constituted of a double filament bulb which incorporates therein two filaments F1 and F2 arranged in the lamp optical axis Lx direction. The first filament F1 situated on a leading end side of the bulb is formed as a first light source for forming low beam light distribution, while the second filament F2 on a bulb base end side is formed as a second light source for forming high beam light distribution. When the bulb 1 is mounted in the reflector 2 using a bulb socket 6, a vertical direction thereof is fixed. On the first filament F1, there is provided a lower surface inner shade 11. A surface of the lower surface inner shade 11 faces downward when the bulb 1 is mounted on the reflector 2. The lower surface inner shade 11 is coated with light-proof material. Light, which is emitted when the first filament F1 is allowed to emit light, is shaded by the lower surface inner shade 11 and is thereby prevented from being radiated more downwardly of the lamp optical axis Lx. On the leading end face of the bulb 1, there is provided a front surface inner shade 12, which is also referred to as a black top, coated with light-proof material in order to prevent the lights of the respective filaments F1 and F2 from being radiated forwardly.
The reflector 2 is generally formed in a substantially container-like shape. Specifically, the reflector 2 includes a first reflector 21 extending in an upper half section area existing upwardly of the lamp optical axis Lx, a second reflector 22 disposed in a vertically extending narrow area existing downwardly of the lamp optical axis Lx and close to the bulb 1, and a third reflector 23 disposed in a wide area existing downwardly of the lamp optical axis Lx and forwardly of the second reflector 22. That is, the first to third reflectors 21 to 23 are assembled together into an integral body, so that the reflector 2 is structured as a composite reflector.
The first reflector 21 has a shape which can be obtained when a rotation elliptic surface having the lamp optical axis Lx as its rotation axis is divided along the rotation axis into two, or a shape approximate to this shape. The first focus P11 of the ellipse is coincident with the light emitting point of the first filament F1, while the second focus P2 is coincident with the rear focus of the projection lens 3. The second reflector 22, similarly, has a shape of a portion of a rotation elliptic surface having the lamp optical axis Lx as its rotation axis, or a shape approximate to this shape, while the first focus P12 of the ellipse is coincident with the light emitting point of the second filament F2. The second focus of the second reflector 22 coincides with the second focus P2 of the first reflector 21. That is, it coincides with the rear focus of the projection lens 3. The third reflector 23 is constituted of a curved surface obtained when a portion of a parabola having the light emitting point of the second filament F2 as its focus is moved around the lamp optical axis Lx along a given locus. This given locus is a locus of a curved line or a combination of a curved line and a straight line which properly corresponds to light distribution required of the lamp unit LU. Also, the third reflector 23 is structured to extend up to an area existing downwardly of the lower end edge of the projection lens 3 which does not face the rear surface of the projection lens 3 in the lamp optical axis Lx direction.
The shade 5 includes a main shade 5M and a sub shade 5S. The main shade 5M is made of a light-proof flat plate disposed near the position of the rear focus P2 of the projection lens 3, exactly, at a position just behind the rear focus P2 in the lamp optical axis Lx direction, while the plane of the main shade 5M is fixed to and supported by the reflector 2 or a holder toward a direction along the lamp optical axis Lx. The shape of the edge portion of the leading end of the main shade 5M is not a simple straight line shape but is a shape which, in order to form a cutoff line in the low beam light distribution, corresponds to this cutoff line. In the case of the main shade 5M, in order to be able to reflect light radiated onto the surfaces thereof, that is, the upper and lower surfaces thereof are light reflection treated.
The sub shade 5S includes a first sub shade 51 disposed at a position existing backwardly of the projection lens 3 and upwardly of the lamp optical axis Lx, and a second sub shade 52 which is situated in an area existing downwardly of the lower end of the projection lens 3 in such a manner that it faces the first sub shade 51 in the vertical direction. The first and second sub shades 51 and 52 are both constituted of a concave mirror, here, a light reflection surface the section shape of which is a rotation parabolic surface shape. The respective parabolic surface focuses of the first and second sub shades 51 and 52 are set at the same position. Here, the specific dimensions and positions of the first and second sub shades 51 and 52 are not described here but will be disclosed in the description which will be given later of light distribution in the lamp turn-on time.
In the lamp unit LU having the above structure, by selecting either the first filament F1 or second filament F2 and by allowing the selected one to emit light, the low beam light distribution and high beam light distribution can be switched over to each other. That is, the first filament F1 is allowed to emit light, the light emitted from the first filament F1 is reflected by the reflector 2, and the light is then concentrated by the projection lens 3, thereby carrying out illumination under the low beam light distribution. Also, the second filament F2 is allowed to emit light, the light emitted from the second filament F2 is reflected by the reflector 2, and the light is concentrated by the projection lens 3 or the light is radiated forwardly without passing through the projection lens 3, thereby carrying out illumination under the high beam light distribution. Next, description will be given specifically of the low beam light distribution and high beam light distribution.
As shown in
Here, since the surface of the main shade 5M is structured to serve as a light reflection surface, the light blocked by the main shade 5M is reflected by the upper surface of the main shade 5M and, after reflected, the light is radiated onto the upper area of the projection lens 3 to provide light b that is projected from the projection lens 3 onto an area existing slightly downwardly of the lamp optical axis Lx. This light b, as stippled in
As shown in
On the other hand, since the second filament F2 is situated backwardly of the first focus P11 of the first reflector 21, the light emitted from the second filament F2 and reflected by the first reflector 21 is not concentrated on the second focus P2 but is reflected toward the upper area of the projection lens 3. Since the first sub shade 51 is disposed on the rear side of the upper area of the projection lens 3, the light reflected by the first reflector 21 is radiated onto the first sub shade 51 so that the light is shaded by the first sub shade 51 and is thus not radiated onto the projection lens 3. On the other hand, since the first sub shade 51 is formed as a reflection surface, the light radiated onto the first sub shade 51 is reflected and concentrated thereby and the thus concentrated light is then radiated onto the second sub shade 52. Since the second sub shade 52 is also formed as a reflection surface, the light radiated thereon is reflected by the second sub shade 52 and is radiated forwardly along the lamp optical axis Lx. The reflected light of the second sub shade 52 provides light f that is emitted forwardly without being radiated onto the projection lens 3.
Consequently, as shown in
Also, a portion of the light reflected by the second reflector 22 is radiated onto and shaded by the lower surface of the main shade 5M. Here, since the lower surface of the main shade 5M is a light reflection surface, the above light is reflected by this lower surface and is radiated onto the lower area of the projection lens 3, thereby providing light g which is projected from the projection lens 3 onto an area existing slightly upwardly of the lamp optical axis Lx. Since this light g, as stippled in
As can also be understood from the foregoing description, the shape, dimensions and positions of the first sub shade 51 are set such that it extends in the following area: that is, an area where the light emitted from the first filament F1 and reflected by the first reflector 21 is not prevented from entering the projection lens 3 and also where the light emitted from the second filament F2 and reflected by the first reflector 21 is allowed to enter. Also, the shape, dimensions and positions of the second sub shade 52 are set such that the light reflected light from the first sub shade 51 can be reflected forwardly without being radiated onto the projection lens 3.
Here, the first sub shade 51 and second sub shade 52 are not limited to the mode of Embodiment 1, provided that the above conditions can be satisfied. For example, as shown in
Also, referring to the plane structure of the first sub shade 51 and second sub shade 52, as shown in
In Embodiment 1, the sub shade 5S is constituted of the first sub shade 51 and second sub shade 52, and the light emitted from the second filament F2 and reflected by the first reflector 21 is reflected forwardly to illuminate the forward area. Alternatively, the light emitted from the second filament F2 and reflected by the first reflector 21 may be shaded by the sub shade 5S, this light may be reflected toward the first reflector 21, and the reflected light may be superimposed on the light distribution that is used to illuminate the forward area.
The light reflection surface of the single sub shade 53 is formed as a conical surface or a portion of a curved surface approximate to a conical surface, or a roof-shaped mirror surface in order that, when the light emitted from the second filament F2 and reflected by the first reflector 21 is radiated onto the single sub shade 53, the thus incident light can be reflected in a direction opposite to the incident light, that is, in the opposite direction to the incident direction, here, in a direction deviated slightly inwardly (toward the lamp optical axis Lx). Specifically, when viewed in the vertical surface direction, the light emitted from the second filament F2 and reflected by the first reflector 21 is reflected in a direction substantially along the lamp optical axis Lx; and, therefore, the vertical section of the light reflection surface of the single sub shade 52 is formed to have a flat or curved surface shape inclined slightly backwardly in order that, after the light reflected by the single sub shade 53 is reflected by the first reflector 21 and is transmitted through the second filament F2, it is allowed to enter the third reflector 23. Here, the section has a slightly dented curved surface shape. Also, since, when viewed in the plane direction, the light emitted from the second filament F2 and reflected by the first reflector 21 is reflected in a direction approaching the lamp optical axis Lx, the plane section of the light reflection surface, as shown in
With Embodiment 2, as the low beam light distribution, of course, there can be provided the same light distribution as shown in
Also, since the second filament F2 is situated backwardly of the first focus P11 of the first reflector 21, the light emitted from the second filament F2 and reflected by the first reflector 21 is reflected toward the upper area of the projection lens 3 without being concentrated onto the second focus P2. Since the single sub shade 53 is disposed in the rear-side upper area of the projection lens 3, the light reflected by the first reflector 21 is radiated onto this single sub shade 53, while the light is shaded by the single sub shade 53 and is thereby prevented from entering the projection lens 3. On the other hand, the light shaded by the single sub shade 53 is reflected by the light reflection surface of the rear surface of the single sub shade 53 backwardly of the lamp, that is, toward the first reflector 21 and, after then, the light is reflected by the first reflector 21 toward the second filament F2. The light radiated toward the second filament F2 passes through within the bulb 1 and is then radiated onto the third reflector 23; and, it is reflected here to provide the light h that is radiated forwardly. The reflection of the light by the single sub shade 53 and the action, in which the thus reflected light is reflected and is radiated forwardly by the third reflector 23, are carried out in the respective vertical surface and horizontal surface directions.
In Embodiment 2, as shown in
Here, in Embodiment 2 as well, since a portion of the light reflected by the first reflector 21 is shaded by the single sub shade 53 and is thereby prevented from entering the projection lens 3, there can be eliminated the light e that illuminates the lower area AU of the illumination area of such high beam light distribution AHi as shown by a chain line in
In order to prevent the above problems, in Embodiment 3, as shown in
In this structure, when a small-sized headlamp is formed such that the distance between the projection lens 3 and reflector 2 is reduced to thereby shorten the longitudinal dimension of the lamp unit LU, the solid angle θ area of the front surface inner shade 12 of the bulb 1 with respect to the rear focus P2 of the projection lens 3 is inclined downwardly with respect to the lamp optical axis Lx, whereby the solid angle θ area does not exist upwardly of the lamp optical axis Lx any longer. Therefore, almost all of the lights, that are emitted from the first filament F1, reflected by the first reflector 21 and concentrated on the second focus, that is, the rear focus P2 of the projection lens 3, are not shaded by the front surface inner shade 12, thereby being able to realize the reduced size of the lamp unit LU without reducing the luminous intensity of the light distribution or wasting the power consumption. Here, since the bulb 1 is lowered by a slight dimension from the lamp optical axis Lx, the center of the light distribution is lowered down slightly. However, its influence on the light distribution can be ignored.
Here, in Embodiment 3, there is illustrated an example of a bulb including a front surface inner shade. However, even in a bulb excluding a front surface inner shade, similarly, in the case that the light reflected by a reflector is radiated onto the leading end face of the bulb, the light is refracted due to the shape of this leading end face and is not concentrated on the rear focus of the projection lens, thereby causing the reduced luminous intensity of the light distribution. Therefore, even in the bulb not having the front surface inner shade, by employing a structure that the center of the bulb is shifted with respect to the lamp optical axis in the above manner, the luminous intensity of the light distribution can be enhanced and the power consumption can be reduced effectively.
In accordance with the above embodiments, a vehicle lighting apparatus may include: a light source device including a first light source and a second light source; a reflector adapted to reflect forwardly light emitted from the light sources; a main shade adapted to shade a portion of light emitted from the first light source and reflected by the reflector; and a sub shade adapted to shade at least a portion of light emitted from the second light source and reflected by the reflector.
In the above structure, a surface of the main shade may comprise a light reflection surface, and said light reflection surface of the main shade may be adapted to reflect forwardly a portion of the light reflected by the reflector.
In the above structure, the sub shade may comprise a light reflection surface, and said light reflection surface of the sub shade may be adapted to reflect forwardly light incident on said light reflection surface of the sub shade.
In the above structure, the sub shade may comprise a light reflection surface, and said light reflection surface of the sub shade may be adapted to reflect light incident on said light reflection surface of the sub shade toward the reflector.
The vehicle lighting apparatus may further include a projection lens adapted to concentrate the light reflected by the reflector. The light sources may be disposed downwardly of a center line of the projection lens.
In the above structure, the light source device may be constituted of a double filament bulb including a first filament serving as the first light source and a second filament serving as the second light source.
In the above structure, the double filament bulb may include a lower surface inner shade, and the lower surface inner shade may be adapted to shade a part of light emitted from the first light source so as to prevent said part of the light emitted from the first light source from being radiated more downwardly of a lamp optical axis.
In the above structure, the main shade may have an edge adapted to form a cutoff line in a light distribution formed by the vehicle lighting apparatus.
According to the above structure, due to provision of the sub shade for shading a portion of the light emitted from the second light source and reflected by the reflector, when obtaining high beam light distribution using the light emitted from the second light source, it is possible to shut off the reflected light of the reflector for illuminating an area just ahead of own vehicle, whereby the degraded visibility caused by the illumination of the just ahead area can be improved.
In addition, according to the above structure, the surface of the main shade is formed as a light reflection surface and a portion of the light reflected by the reflector is reflected forwardly by this light reflection surface, whereby the thus reflected light can enhance the luminous intensity of the partial area of the light distribution. This can advantageously enhance the visibility of a driver for an area existing ahead of the driver's own vehicle and can make effective use of the light to thereby save the power consumption. Further, according to the above structure, the sub shade is formed as a light reflection surface and the sub shade is structured such that it reflects the light to be shaded forwardly or toward the reflector, whereby the light to be shaded by the sub shade can be radiated directly or after it is reflected again by the reflector to superimpose the light on the light distribution to thereby enhance the luminous intensity of the light distribution, so that the characteristics of the light distribution can be improved and the power can be used effectively. Also, according to the above structure, since the light sources are shifted downwardly of the center line of the projection lens, the light sources can be disposed near the projection lens without shutting off the reflected light of the reflector by the light source device. This can shorten the dimension of the lighting apparatus in the optical axis direction and thus the size of the lighting apparatus can be reduced.
Although, in the above embodiments, the invention is applied to a lamp unit including a double filament bulb, the invention can also be applied similarly to a headlamp structured such that two independent bulbs are disposed in the lamp optical axis direction and the on and off of these bulbs are switched over to each other to thereby switch the light distribution. Also, the structures of the reflectors in the above embodiments are not limitative, that is, the structures of the first to third reflectors are not limited to those employed in the above embodiments.
It goes without saying that the vehicle lighting apparatus according to the invention can be applied not only to a headlamp for use in a four-wheel vehicle but also to a headlamp for use in a two-wheeled vehicle such as a motorcycle.
The invention can be applied to a vehicle lighting apparatus structured such that two light sources are switched over to each other to thereby obtain different kinds of light distribution.
Number | Date | Country | Kind |
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2010-248012 | Nov 2010 | JP | national |
2011-094630 | Apr 2011 | JP | national |