|Publication number||USRE34318 E|
|Application number||US 07/666,118|
|Publication date||Jul 20, 1993|
|Filing date||Mar 6, 1991|
|Priority date||Nov 23, 1987|
|Publication number||07666118, 666118, US RE34318 E, US RE34318E, US-E-RE34318, USRE34318 E, USRE34318E|
|Inventors||John M. Davenport, Richard L. Hansler|
|Original Assignee||General Electric Company|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Referenced by (16), Classifications (18), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to a lighting system. and more particularly, to a lighting system comprised of subsystems each utilizing a high brightness light source which is coupled to fiber optics so as to emit a desired illumination pattern form an optical strip arranged across a vehicle such as an automobile, truck, bus, van, tractor or aircraft.
It is well known that fiber optics may be used efficiently to carry or conduct the output of a light source to various locations without encountering any substantial transmission losses thereof. The light conducted by the optical fibers is confined or condensed to the relatively small dimensions of the fibers themselves and may find various related space restrictive applications in automobiles and aircraft or other vehicles concerned with aerodynamic styling and efficiency.
For example, automotive styling must take into account the amount of frontal area necessary to provide the forward illumination needs for the automobile and provide means to reduce that area, and in particular, the height so as to satisfy aerodynamic considerations. Similarly, it is desired that the exposed area of the automobile necessary to provide its rearward illumination, such as stop and tail license plate and back up illumination, be reduced so as to accommodate aerodynamic styling. Further, it is desired that the side illumination of a vehicle such as said markers be adapted to aerodynamic styling considerations. Still further, the interior lighting for a vehicle such as glove compartment and interior lights should be considered for styling and efficiency implications. The use of fiber optics that conduct light within small confines are adaptable to these aerodynamic considerations. Further, fiber optics are advantageously adaptable to provide the overall illumination needs of the vehicle.
One such aerodynamic consideration is to provide forward illumination by light generated at a remote location coupled by fiber optics and emitted from a relatively small optical strip arranged across the frontal area of the automobile. One of the major areas of concern in efficiently utilizing optical fibers is the coupling of a sufficient amount of energy from a light source into these optical fibers to serve the needs of the automobile, aircraft, or other vehicle in which the fibers are employed. The coupling of such energy is dependent upon the intensity of the light source, the size of the optical fibers, and the distance between them. Each of these parameters has certain limitations that hinder the employment of optical fibers for optical systems for vehicles, automobiles or aircraft. For example, forward illumination emitted from an optical strip spread across an automobile may require such an intensity light source that has relatively large dimensions, compared to conventional headlamps, that prevents it from being conveniently housed on an automobile. Further, the illumination must be of a prescribed amount and distribution to satisfy the forward and glare considerations of the automobile which may not be feasible by having the light emitted from a strip arranged across a vehicle, automobile or aircraft. It is desired that these limitations be reduced or even eliminated and that a lighting system be provided that has efficient coupling between the optical fibers and the light source, and further that illumination be provided that meets and exceeds the needs of the vehicle, automobile or aircraft.
Accordingly, it is an object of the present invention to provide means for efficient coupling between the fiber optics and light source of a lighting system.
It is a further object of the present invention to provide a lighting system employing optical fibers that provides desired illumination patterns of efficient amount and of prescribed patterns to meet and exceed the needs of the vehicle, automobile and aircraft.
The present invention is directed to a lighting system particularly suited to the aerodynamic considerations of vehicles, including automobiles, aircraft and the like to allow design flexibility and to provide an overall lighting system for the vehicle.
The lighting system includes subsystem each comprising a high intensity light source capable of being selectively energized and a plurality of optical carrying devices, preferably optical fibers, with each having one end predeterminedly coupled to the light source and the other end of each of the optical fibers preferably predeterminedly positioned in close proximity to respective reflective elements. Each of the reflective elements are respectively arranged with alens element capable of being mounted on an external surface of a device. The lens elements each provide a prescribed illumination pattern when the light source is activated.
In another embodiment of the subsystem, the optical fibers are routed directly to their respective lens elements thereby eliminating the need of the reflective elements. In either embodiment the optical fibers are predeterminedly positioned at the focal length of their respective lens elements.
One embodiment of the lighting system includes two subsystems each having a high intensity light source respectively coupled to one end of a first and second plurality of optical fibers. The other end of the first and second plurality of optical fibers are arranged so that one optical fiber form the first high intensity source is arranged with one optical fiber from the other high intensity source and both are positioned in close proximity to a reflective element. The reflective elements related to the first and second plurality of fibers are arranged relative to a first plurality of lens elements mounted across the frontal area of an automobile. The plurality of reflective elements are arranged relative to the optical fibers so as to direct the light from each of the high intensity sources into the lens elements so that upon the selective activation of either or both of the high intensity sources, the lens elements respectively provide the forward low and high beam illumination patterns for the automobile. In another embodiment of the lighting system, two subsystems develop the low and high beam illumination without the need of reflective elements.
FIG. 1 is a schematic illustration of one embodiment of the present invention related to a lighting system that provides the forward illumination of a vehicle.
FIG. 2 illustrates the placement of a plurality of fiber optics relative to the filament of a relatively small high intensity light source.
FIG. 3 is a schematic illustration of the parameters related to the transmission of the light output from a portion of the high intensity light source to one of the optical lenses illustrated in FIG. 1.
FIG. 4 illustrates the directing and combining of the illumination from a first and a second high intensity light source by a reflective element into one of the optical lenses shown in FIG. 1.
FIG. 5 is a schematic illustration of a lighting system that provides the forward illumination of a vehicle utilizing a high intensity light source coupled to a plurality of optical fibers by means of a ellipsoidal reflector.
FIG. 6 illustrates the directing and combining of the illumination from a first and a second high intensity light source, without the use of a reflective element, into one of the optical lenses of FIG. 1.
FIG. 7 illustrates the ellipsoidal reflector focusing of the light rays emitted from a high intensity source into the plurality of optical fibers.
Referring to the drawing, FIG. 1 illustrates a subsystem 10 related to the overall lighting system of the present invention. The subsystem 10 illustrated in FIG. 1 for one embodiment of the present invention provides the forward illumination that is particularly suited for aerodynamically styled vehicles such as automobiles or aircrafts. The subsystem 10, along with other subsystems of the lighting system of the present invention, includes a high intensity light source 12 capable of being selectively energized, and a plurality of optical carrying devices such as optical fibers 141...14N, each having one end predeterminedly coupled to the light source 12 with the other end of the optical fibers of the embodiment of FIG. 1 preferably predeterminedly positioned in close proximity to respective reflective elements 161 . . . 16N. The reflective elements 161 . . . 16N are preferably provided to be advantageously positioned relative to fiber optics 141 . . . 14N so as to reduce or even eliminate any bending of fiber optics 141 . . . 14N that may adversely effect the light carrying capabilities of the fiber optics 141 . . . 14N. The use of reflective elements 161 . . . 16N provide more flexibility relative to the routing of the fiber optic elements 141 . . . 14N within the confines of the vehicle, automobile and aircraft.
Each of the respective reflective elements 161...16N respectively direct light rays 181... 18N into lens elements 201...20N which are capable of being mounted on the frontal area of a vehicle such as an automobile or air craft. The lens elements 201...20N have a circular shape when viewed from the front (not shown) and provide, as will be described, prescribed illumination patterns when the light source 12 is selectively activated.
The high intensity light source illustrated in FIG. 1 is a tubular-like device having an incandescent filament 12A that may be selectively energized by an external source by way of terminals 12B and 12C. The plurality of optical fibers 141...1415 each have one of their ends coupled to one side of the high intensity source 12, whereas, the optical fibers 1416...14N each have one of their ends coupled to the other side of the high intensity light source 12. The other ends of the optical fibers 141...14N,upon the activation of light source 12, each emit light that respectively impinges onto reflective element 161...16N.
FIG. 1 shows an arrangement comprising thirty (30) of each of the optical fibers 14, reflective elements 16, and the lens elements 20. The lens elements 20 are positioned in a contoured manner across the left side of the frontal area (not shown) of a vehicle such as an automobile and up to the centerline 22 of the automobile. The automobile has a complementary arrangement of the subsystem 10 shown in FIG. 1 on the other side of the centerline 22 so that predetermined light patterns, to be described, are emitted from a relatively small optical strip exposed on and across the majority of the frontal surface of the automobile. The light developed by the subsystem 10 of FIG. 1 serves as the low beam illumination of an aerodynamically styled automobile.
The development of such low beam illumination may be described with reference to FIG. 2 showing a portion of the coupling of the high intensity incandescent light source 12 to a plurality of optical fibers. The high intensity light source 12 is preferably of a quartz material and consists of a quartz tubular member having a relatively small overall length of about 30 mm. a neck portion with a diameter of about 3 mm, and a central portion with an outer diameter of about 4 mm. The filament 12A of light source has an outer diameter dimension 12D of about 1.8 mm. The central portion of the filament 12A is spaced from the outer walls of the light source 12 by an amount 12E having a value of about 1.6 mm. The light source 12 has a relatively large length to diameter ratio such as 30 to 4. The light source 12, having relatively small dimensions, upon its selective activation by the automotive switching system, yields a high intensity light output of about 2000 lumens.
The optical fibers shown in FIG. 2 have a diameter of about 1.5 mm and are preferably formed of a high temperature material such as quartz or glass to allow the fibers to be brought into close proximity with and even directly contacting the relatively hot operating high intensity light source 12 as shown in FIG. 2. The fibers of 1.5 mm diameter are arranged in line almost touching each other and almost touching the light source while extending about 25 mm along each side of the light source. The other end of each of the optical fibers, such as the other end of fiber 141, shown in FIG. 3, are predeterminately positioned relative to a reflective member, such as 161 related to fiber 141. The reflective members, such as 161, may have an aluminized reflective surface and dimensions of 4×8 mm.
FIG. 3 shows a portion of slice, in the vertical plane, of the filament 12A related to optical fiber 141 looking down into the high intensity light source 12. The previously discussed dimensions 12D and 12E of source 12 are respectively shown in FIG. 3 as diameter D2 and focal length Fl2. The angle at which the light rays emitted by the filament 12 enter the optical fiber 14, in the vertical direction is shown as θ. Considering the previously given dimensions (12D =1.8 mm and 12E =1.6 mm) yields an angle θ of about 54° but this angle θ may be of an amount form about 40° to about 60° . It is preferred that the optical fiber 141...14N be positioned relative to the filament having a predetermined diameter so that the spacing between the optical fibers and the mid-portion of the filament is approximately equal to the predetermined diameter of the filament. This angle θ is also that of the light rays exiting the optic fiber 141 and impinging the reflective element 161. Further the angle θ is also the angle which defines the cone of light 181 directed to the related lens element 201.
The angle θ is also representative of the f/number of the lens element 201 which may be expressed by the relationship: where fl1 is the focal length of the lens element 201, and D1 is the diameter of the lens element 201.
The lens 201, has a focal length fl, preferably in the range of 15 to 30 mm. The lens element 201 may be an aspheric lens which corrects for spherical aberration. Such an aspheric lens is particularly suited for small f/number such as 0.06 to 1. The lens 201 may also be a fresnel type particularly suited for small f/numbers applications. Both the aspheric and fresnel lenses may be molded from plastic and are preferably formed in one continuous strip of thirty (30) with each of such lenses having a length and a width of about one (1) inch. For the embodiment of FIG. 1, the composite strip of lenses 201...20N is molded such that it conforms to the shape of the front end of an automobile or an airplane and the lenses are oriented so as to direct the light in a forward direction. The composite strip of lenses may also have on its outer surface a clear flat plastic which conforms to the outer metal surfaces and may provide a window through which light emitted by the subsystem of FIG. 1 passes.
The coupling of the light from the high intensity light source 12 to the plurality of optical fibers 141...14N is dependent upon the size or lumen output of the light source, the size of the fiber, and the distance between the fiber and the light source. For a small spherical light source and optical fiber, the coupled light will vary as the square of the distance between the source and the fibers. For the incandescent light source 12 having a large length to diameter ratio, the amount of light collected by the fibers essentially varies inversely as the first power of the distance between the source and the fibers. Accordingly, the closer the fibers can be brought to the filament of the light source the more light that will be collected by the fibers themselves. This is achieved by the present invention in which the fibers are preferably brought into direct contact with the outer walls of the light source as shown in FIG. 2.
The angle θ at which the light rays enter the optical fibers 141...14N, previously discussed, is about 60° total angle in the vertical direction. This same angle is preserved in the light emitted by the fibers and essentially all such light is collected by the lens and collimated thereby. In the horizontal plane the fiber receives light from the whole length of the filament. This light is lost when it emerges from the fibers since it will not strike the reflective elements 161...16N and therefore is not directed to the lenses 201...20N but rather is absorbed in baffles positioned between the lenses 201...20N.
The beam of light developed by the practice of this invention and which emerges from the lenses, as to be further discussed with regard to FIG. 4, is from about 3° to about 6° total angle depending on the diameter of the fiber and the focal length of the lens. For the arrangement shown in FIG. 3 that produces a beam in the form of a circle of 3.4°, the planar reflective element 16 is disposed as close as possible to the fiber optics and is tilted at an angle such as to center the image of the end of the fiber on the axis of the lens is at a distance equal to the focal length fl2 of the lens.
For the embodiment disclosed with regard to FIG. 3, the amount of light collected by each of the optical fibers is about 15 lumens. Considering that there are thirty (30) optical fibers associated with the light source 12 as shown in FIG. 1, the amount of lumen output developed by the present invention is 30×15=450 lumens which when coupled with the light from the unit on the other side having the embodiment shown in FIG. 1, provides the low beam illumination needs of an automobile.
The size of the beam produced by the focus of light emitted by optics that intercepts the respective reflective element and which impinges onto and is transmitted by the lens should also take into account the parameters of the lens itself. The size of the beam produced by a lens having a focal length of 25 mm developed from a fiber optical having a diameter of 1.5 mm is =1.5/25 which is equal to 0.06 radians which may be expressed as 3.4 degrees. Each of the fiber optics lens combinations (141...14N, and 201...20N) produces a uniform circle of light with a well defined edge where the angle between the edges is 3.4°. For a lens 20 having a focal length of 20 mm formed from the light emitted from 1.5 mm fiber, the angle produced is 4.3°. This is still an acceptable small angle for the automotive application. The desired light pattern emitted from the plurality of lenses 20 is produced by overlapping the light circles produced by the plurality of lenses. Because of the sharply defined light circle of each lens, the overall light pattern has a minimum glare factor and since there is virtually no uncontrolled light, the forward illumination of the automobile is particularly suited for low beam applications for driving in fog, rain or snow.
To provide for both the low and the high beam illumination of an automobile, two high intensity lamps and two sets of a plurality of optic fibers may be used and may be described with reference to FIG. 4 shows fiber optic 141, also indicated as A, related to the first light source 12 and fiber optics 281, also indicated as B, which is one of a plurality of fiber optics each having one of their ends coupled to a second light source (not shown) in a manner as described with regard to FIGS. 2 and 3 related to fiber optics 141...14N. Each of the fiber optics A and B are positioned in close proximity to each other and at angles α and γ, respectively, relative to the center line of the lens, 201. Reflective element 30 is a 90° prism molded from plastic in which total internal reflection occurs to deflect the light.
The fiber optics A is positioned at the angle relative to the centerline which is approximately 3-5°. The fiber optic B is positioned on the optical axis. The light rays emitted by fiber optic A which impinge and are reflected and directed by element 30 to lens 201 are indicated as A, whereas, similar rays related to fiber optic B are indicated as B. The light rays A shown being transmitted by lens 201 are parallel to each other, and similarly, the light rays B transmitted by lens 201 are parallel to each other. The fiber optic B is positioned on-axis, that is γ=90°, relative to lens 201. The fiber optic A is positioned off-axis about 3° to 5° so as to provide light transmitted from lens 201 shifted to the left and above the light rays B. The light rays B provide the low beam illumination of the automobile, whereas, light rays A provide the high beam illumination of the automobile.
The operation of the arrangement shown in FIG. 4 produces a proper light beam pattern for both the high and low illumination of the automobile. The centers of the two patterns respectively produced by each high intensity light sources related to the two plurality of optical fibers 141...14N and 281...28N are limited approximately to a separation of about 3° to about 5° if the ends of the fibers are placed next to each other relative to the respective reflective elements. Because the two beams are developed from separate light sources both beams upon the proper selection of the automotive switching system may be used separately or together to provide the high beam frontal illumination for vehicles, automotives and aircraft under consideration. If desired, light filtering, for example, between the reflective element and the lens, may be provided so as to develop some color, such as yellow, in the high beam illumination which finds adaptation in some countries such as France. This light filtering may also be used for the low beam applications.
A second embodiment of the present invention of a lighting subsystem 40 is shown in FIG. 5 as having a plurality of lens 201...20N arranged in a contoured manner on each side of the automobile in a manner as described with regard to FIG. 1. The subsystem 40 of FIG. 5 is different from that of subsystem 10 of FIG. 1 in that it is devoid of reflective elements allowing the light output 181...18N from fiber optics 141...14N and 281...28N to be respectively routed directly to lens elements 201...20N. Further, the light coupled to the fiber optics 141...14N related to the low beam illumination, is generated by a first high intensity light source 42 arranged in one embodiment at one focue of an elliptical reflector 44 in a manner as to be described with regard to FIG. 7. The light coupled to the fiber optics 281...28N, related to the high beam illumination, is generated by a second high intensity light source (not shown) in a manner similar to that of elliptical reflector 44. The manner in which light emitted by fiber optics 141...14N and 281...28N is combined and collimated by lens elements 201... 20N may be described with regard to FIG. 6.
In a manner similar to FIG. 4, FIG. 6 shows the fiber optics 141 and 281 positioned along and at a distance equal to the focal length fl2 of the lens 201. FIG. 6 also shows the central portion of the fiber optics 281 (B), related to the high beam illumination, arranged on-axis of lens element 201, whereas, the central portion of the fiber optics 141 (A) is arranged off-axis of lens element 201 by an angle having the typical value of about 3° to about 5°. Further, the light rays shown in FIG. 6 transmitted from fiber optics 141 and collimated by lens 201 are indicated by A and are parallel to each other. Similarly, the light rays transmitted from fiber optics 281 and collimated by lens 201 are indicated by B and are parallel to each other. The operation of the arrangement of FIG. 6 develops separately or together light beam patterns that are separated from each other by an angle limited approximately to a value of about 3.4° so as to provide the low and high beam illumination for the vehicle, automobile or aircraft employing this invention in a similar manner as described with regard to FIG. 4.
The arrangement of the first high intensity light source 42 positioned at one focus of elliptical reflector 44 related to one embodiment of the present invention and coupled to fiber optics 141...14N along with the second high intensity light source (not shown) coupled to fiber optics 281...28N may be described with reference to FIG. 7. The exposed faces of the plurality of fibers 141...14N and also the faces of the fibers 281...28N (not shown) are arranged at the second focus of the elliptical reflector 44. The high intensity light source 42 may be of an incandescent type previously discussed with regard to light source 12 or it may be a discharge lamp comprised of spaced apart electrodes and having a metallic or metal halide ingredient along with a gaseous fill. The discharge lamp 42 preferably has a light output of 2000 lumens. The discharge lamp 42 is preferably of a miniature type such as described in U.S. Pat. No. 4,161,672, assigned to the same assignee as the present invention, incorporated herein by reference and to which reference may be made for further details of its operation. The elliptical reflector 44 is preferably of a type described in U.S. Pat. No. 4,021,659, assigned to the same assignee as the present invention, incorporated herein by reference and to which reference may be made for further details of its operation.
In the operation of the arrangement of FIG. 7, the placement of the central portion of the light source 42 at one focal point 48 of reflector 44 and the bundle of optical fibers at the other focal point of reflector 44, causes the vast majority of the light rays, such as rays 52 and 54, emitted by light source 42 to be intercepted and reflected by reflector 44 so as to enter the exposed faces of the plurality of optical fiber 141...14N at the desired angle θ of about 54° having a range of about 40° to about 60° previously discussed with regard to FIG. 3. The operation of the arrangement of FIG. 6 is advantageous in that it eliminates the need of bringing the optical fibers into close proximity with the light source 42, while at the same time, providse sufficient couplling from the light source 42 to the optical fibers so as to provide the desired low beam and high beam illumination for the automobile or aircraft in a manner as described with regard to FIGS. 4 and 6. The ability of locating light source 42 remotely from the fiber optics 141...14N also allows flexibility in locating and routing of the fiber optics within the housing, such as the automobile or aircraft, so as to minimize or eliminate any bending of the fiber optics 141...NN and thereby eliminating the need of reflective elements 161...16N described with regard to FIG. 1.
It should now be appreciated that the arrangements of the embodiments of FIGS. 5 and 1 provide for subsystems 40 and 10, respectively, that are particularly suited for aerodynamically styled vehicles, automobiles or aircraft. The practice of the present invention provides a means of coupling a sufficient amount of light from the light source to the optical fibers so as to provide for the overall illumination needs of the aerodynamically styled vehicles, automobiles and aircraft. The illumination provided by the practice of the present invention more than satisfies the low and the high beam needs of the aerodynamically styled automobile.
One or more of the subsystems 40 or 10 may be interconnected to comprise the overall lighting system for various applications finding applicability for the aerodynamically designed, vehicle, automobile and aircraft. In such a lighting system the high intensity light source of the subsystem may be energized to serve the illumination needs for any particular application. The lens of the subsystem may be located and directed to emit light in a desired beam pattern and at a particular level of intensity. For example, the subsystem of the present invention may be employed to provide for the rearward illumination of a vehicle, such as stop and tail light, license plate, and back up applications. For such usage, the light source is selectively activated by the automotive switching subsystem and the lens members are appropriately mounted on the desired rear portions of the automobile. For the rearward illumination, only one optical fiber for each light source is necessary to conduct the light to the appropriate lens element. The subsystem of the present invention may also find application to serve the needs of the interior of a vehicle such as the interior and glove compartment illumination. Similarly, the practice of the present invention provides for lighting for other vehicle or aircraft needs, such as side illumination of a vehicle of landing lights and marker lights, in thin winged planes. Further, the practice of the present invention may also provide the desired illumination for sign lighting and other lighting applications.
The practice of the present invention may provide for all of the illumination needs of vehicles, automobiles or aircraft. The invention contemplates that one or more high intensity light sources may be appropriately housed within the vehicle, automobile or aircraft and its light output distributed throughout by means of fiber optic elements to the appropriately positioned lens elements. The activation of the one or more high intensity light sources along with the lens element may be accomplished by appropriate switching means of the vehicle, automobile or aircraft in which the invention finds application.
Although the previous description related to FIG. 1 was discussed as having a reflective element for directing the light from an optical fiber into the lens elements situated on a housing, it should be recognized that the practice of the present inventioon contemplates that the optical fiber discussed with regard to FIG. 1 could be routed directly to the lens element and thereby eliminate the need of the reflective elements shown in FIG. 1. Further, it should be recognized that the optical fiber could be routed directly to an appropriate housing and eliminate the need of both the reflective and lens elements.
It should now be appreciated that the practice of the present invention provides a means of producing controlled light patterns initiated from one or more high intensity light sources which are effectively coupled to one end of a plurality of optical fibers that can either be brought into close proximity to the light source or the fibers may be located remotely from the light source by means such as a focussing elliptical reflector. The other ends of the fibers then serve as a secondary light source for the optical systems having other means to combine and collimate the light rays of the light source into one or more desired light patterns to serve the needs of the aerodynamically designed vehicles, automobiles or aircrafts.
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|U.S. Classification||362/511, 362/554|
|International Classification||F21S8/12, F21S8/10, B60Q1/00, F21V8/00|
|Cooperative Classification||F21S48/2287, G02B6/0008, G02B6/0006, F21S48/2293, F21S48/1241, B60Q1/0011|
|European Classification||F21S48/12T4, F21S48/22T4T, F21S48/22T4S4, B60Q1/00B, G02B6/00L4E, G02B6/00L4C|
|Mar 9, 1997||LAPS||Lapse for failure to pay maintenance fees|
|May 20, 1997||FP||Expired due to failure to pay maintenance fee|
Effective date: 19970312
|Jul 6, 2000||FPAY||Fee payment|
Year of fee payment: 12