Abstract:
A CHMSL ( 16 ) or other lighting system feature of an automobile ( 10 ) includes a feature for presenting personal expressions in the form of words or symbols but is automatically deactivated when the regular vehicle lighting system is in use. The personal expression is fixed in a tangible medium by way of phosphor-coated indicia ( 34 ) placed within a UV impervious housing ( 18 ). A secondary UV light source ( 36 ) selectively energizes the phosphor-coated indicia ( 34 ) so that the irradiated material glows and is visible through a light transmissive screen ( 20 ). The light transmissive screen ( 20 ) is provided with a UV blocking agent so that harmful UV rays do not escape the housing ( 18 ). The phosphor-coated indicia ( 34 ) can be mounted on a removable transparent plate ( 30 ), on light dispersion optics ( 24, 26 ), or on the inner face of the light transmissive screen ( 20 ). A control circuit ( 42 ″) manages the primary light source ( 22 ) and the secondary UV light source ( 36 ) so that only one of the light sources can be energized at any one time.

Description:
This invention claims priority to U.S. Provisional Patent Application No. 60/588,481, filed Jul. 16, 2004. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     An ultraviolet light induced indicia for a motor vehicle, and more particularly, a stop or other external lighting system capable of displaying a UV light induced indicia when not in regular use as a stop or other light feature. 
     2. Related Art 
     Center high mounted stop lamp (CHMSL) assemblies for motor vehicles are one example of a regular light assembly having a primary purpose in this case of indicating a braking condition. CHMSL&#39;s are typically mounted in the rear window, or on the rear deck, of an automobile and are wired to light an elongated generally rectangular region with the brake-light system. They provide increased visibility to the brake-light system, and thus comprise an important part of the vehicle safety system. 
     Bumper stickers and other rear vehicle signage have become an accepted part of self-expression. Most bumper stickers or other signage, however, are difficult to perceive at night or in other low level light conditions. Thus, the self-expression of an individual through the medium of vehicle signage and bumper stickers is generally limited to daylight conditions. Furthermore, the available space for self-expression indicia is somewhat limited on the rearward surface of the vehicle. For example, it is not possible to cover the spaces reserved for CHMSL and other lighting features because of the safety issues. 
     Any device or technique which is aesthetically pleasing would be readily accepted within the automobile industry. Thus, there exists a need for an improved, aesthetically appealing technique to present signage, indicia, or other forms of expression on the rear of a vehicle, and particularly during nighttime conditions and in regions of the vehicle surface not heretofore available. 
     SUMMARY OF THE INVENTION 
     A motor vehicle is provided having a rearwardly facing exterior surface. The vehicle comprises a housing having a light transmissive screen presented toward the rearwardly facing exterior surface. A primary visible light source is disposed in the housing for projecting visible light along a path toward the light transmissive screen. Phosphor-coated indicia are disposed in the housing and are positioned in the light path. A secondary ultraviolet light source within the housing is selectively energized for projecting ultraviolet light onto the phosphor-coated indicia to produce a visually interesting display through the light transmissive screen for the benefit of viewers positioned rearwardly of the vehicle. 
     A vehicular lighting system according to this construction is particularly advantageous. New regions of the rearwardly facing exterior surface of the vehicle are made available for presenting signage or other expressive indicia. The primary visible light source can be a feature of the vehicle rearward lighting system such as used for brake lights, signal lights, marker lights, or other use. Thus, this novel vehicular lighting fixture advantageously combines in a single housing, a traditional vehicular lighting feature operated through the primary visible light source, as well as a secondary phosphor-coated indicia via activation of a secondary ultraviolet light source within the same housing. 
     According to another aspect of the invention, a method for selectively presenting lighted indicia from an automobile comprises the steps of: containing a primary visible light source, a secondary ultraviolet light source, and a phosphor-coated indicia within an ultraviolet light impervious housing; irradiating the phosphor-coated indicia with ultraviolet light while the primary visible light source remains inactive; and automatically de-energizing the secondary ultraviolet light source in response to energizing the primary visible light source. 
     The method of the invention controls conflict between the primary and secondary uses of the lighting fixture by automatically de-energizing the secondary ultraviolet light source whenever the lighting fixture is needed for its primary purpose. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein: 
         FIG. 1  is a perspective view of an automobile including a CHMSL assembly mounted above its rear window; 
         FIG. 2  is a simplified cross-section showing a first embodiment of the subject invention; 
         FIG. 3  is a simplified view showing the phosphor-coated indicia in a transparent, inactive state with flanking UV light sources in a de-energized condition; 
         FIG. 4  is a view as in  FIG. 3 , but showing the phosphor-coated indicia as irradiated by the ultraviolet light sources to emit an appealing visible light color; 
         FIG. 5  is a schematic view showing an alternative embodiment of the subject invention with the phosphor-coated indicia being affixed to diffusion optics; and 
         FIG. 6  is a schematic view showing a second alternative embodiment wherein the phosphor-coated indicia are affixed to the inside of the ultraviolet screen. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the figures, wherein like numerals indicate like or corresponding parts throughout the several views, a representative automobile is generally shown at  10  in  FIG. 1 . The automobile  10  includes a rearwardly facing exterior surface which includes a rear window  12 , a pair of rear brake light assemblies  14 , and other standard features. A CHMSL assembly, generally indicated at  16 , is supported for viewing through the rear window  12 . When a driver touches the brake pedal and thus activates the braking system, the CHMSL assembly  16  is energized, together with the brake lights  14 , to illuminate an elongated, generally rectangular red region signaling rearward drivers of a brake-induced deceleration. 
     Referring to  FIG. 2 , the CHMSL  16  includes a housing  18  which is mounted or fixed to the vehicle  10 . In some vehicles, the housing  18  will be suspended from the inner roof or headliner portion, whereas in other vehicles the housing  18  will be mounted on a rear deck lid or exterior of the vehicle on the trunk lid. Alternatively, the housing  18  need not be a part of the CHMSL  16  per se. Rather, it can be incorporated into a dome light assembly, a rear brake light assembly, or other such structure. The housing  18  includes a light transmissive screen  20  presented in the rearwardly facing direction. Typically, although not necessarily, the light transmissive screen  20  will comprise the closing end of the housing  18  through which only visible light may pass. The light transmissive screen  20  can possess optical characteristics, such as lensing or coloration attributes as may be deemed necessary. Furthermore, the light transmissive screen  20  can, in some circumstances, be formed integrally with the rear window  12  of the vehicle  10 . 
     One or more primary visible light sources  22  are disposed in the housing  18  for projecting visible light along a path toward the light transmissive screen  20 . In the preferred embodiment, the primary visible light source comprises an array of light emitting diodes (LED&#39;s) or other light generating elements having favorable power consumption, size and temperature attributes. Notwithstanding, a single light source  22  of sufficient light output intensity could be used with similar effectiveness. The primary light source  22  is positioned within the housing  18 , horizontally transverse within the automobile  10 , such that the light emitted from the light sources  22  is projected into a translucent material having a shape which causes the light to spread and reflect within it. The translucent material shape may be in the form of a collector  24  and a diffuser  26 , joined end-to-end with or without gap between. The collector  24  and diffuser  26  may be made from a silicone material, although other materials known to those skilled in the art may also be used such as epoxy or urethane or opaque materials. 
     The combination diffuser  26  and collector  24  are structured to help evenly mix and spread the light patterns from the multiple light sources  22 , and direct these light patterns through an exit face  28  of the diffuser  26 . Although shown in the drawings as a single piece, the collector  24 /diffuser  26  can be spaced one from another and can also be designed as an array of multiple sub-units serving each one or two individual light sources  22 . 
     Light emanating from the exit face  28 , along the path of light, passes into another optical feature in the form of a substantially transparent plate  30 . The transparent plate  30  can be permanently affixed in the housing  18 , or more preferably can be removably supported on an interchange mechanism  32  that will allow convenient, user friendly substitution with a different transparent plate  30 . A phosphor-coated indicia is disposed on one face of the transparent plate  30 . Phosphor materials such a strontium, zinc, cadmium sulfides, or any other material or pigment that absorbs light energy and radiates visible light when exposed to ultraviolet light can be used. Different phosphor materials and blends of materials can be selected to radiate different visible light colors. Regardless of the particular phosphor material chosen, it is preferably of a type which is generally transparent or invisible in the absence of ultraviolet light. 
     A secondary ultraviolet light source  36  is also provided within the housing  18 . The secondary ultraviolet light source  36  is selectively energized to project ultraviolet light onto the phosphor-coated indicia  34  to produce a visually interesting display through the light transmissive screen  20  for the benefit of viewers positioned rearwardly of the vehicle. Thus, when the secondary ultraviolet light source  36  is activated, the phosphor-coated indicia  34  absorbs light energy at the relevant wave lengths and then radiates visible light. Light colorations for the primary light source  22 , such as “red” for stop light applications, will be created in the light path upstream of the indicia  34  so as not to affect or alter the visual distinctiveness of the glowing indicia  34 . For example, the red color for a stop light application can be achieved through a red light emitting primary light source  22 , or coloring agents or films used with the collector  24 /diffuser  26 . 
     The light transmissive screen  20  can be provided with an ultraviolet light blocking agent so that UV light cannot escape from the housing  18 . The remainder of the housing  18  is also made from a material impervious to the passage of ultraviolet light. By this means, UV light emitted from the secondary light source  36  is completely undetectable to an outside observer. Nevertheless, the UV light causes the phosphor-coated indicia  34  to glow with visible light colors rendering an impressive visual effect. The UV blocking agent incorporated into the light transmissive screen  20  can be in the form of a film applied to the inner surface of the screen  20 , as depicted in  FIG. 2 , or the light transmissive screen  20  can be doped with an appropriate UV blocking material. Other techniques may also be employed. 
       FIG. 3  is a simplified perspective view of the transparent plate  30  with the phosphor-coated indicia  34  being arranged to form the arbitrary and exemplary word “TEAM”. Here, the secondary ultraviolet light sources  36  are shown in an inactive state, and as a result the phosphor-coated indicia  34  are substantially invisible or undetectable to an outside observer. Accordingly, if the CHMSL  16  is activated with the brake light system, light from the primary light source  22 , acting through the collector  24 /diffuser  26 , is projected through the light transmissive screen  20  without the phosphor-coated indicia being noticeable. However, when the secondary ultraviolet light sources  36  are energized, as shown in  FIG. 4 , the UV light irradiates the phosphor-coated indicia  34  causing it to glow. Thus, observers, particularly those positioned rearwardly of the automobile  10 , would be able to discern the phosphor-coated indicia  34 , especially at night, and thus appreciate the intended expression. Preferably, the glowing indicia  34  can remain energized at the same time as the primary light source  22  without adversely affecting the color output from the primary light source  22 . Thus, if the primary light source  22  operates as a red stop like, for example, then the indicia  34  can remain glowing without unduly changing the red color perceived by an observer. However, if the color alternation is not acceptable, a control circuit can be used to electronically interconnect the primary visible light source  22  and the secondary ultraviolet light source  36  in such a manner that the secondary ultraviolet light source  36  can only be energized when the primary visible light source  22  is de-energized. Thus, conflicts between the two lighting systems, operating through the common CHMSL assembly  16  and housing  18  are never problematic. 
     Referring now to  FIG. 5 , a first alternative embodiment of the invention is depicted. For convenience, prime (′) designations are used with corresponding previous reference numerals in this example. Here, the CHMSL assembly  16 ′ includes a primary light source  22 ′ positioned adjacent a collector  24 ′ and diffuser  26 ′. These features are similar in design and functionality to the previous embodiment. In this application, however, the transparent plate  30  is omitted and the phosphor-coated indicia  34 ′ is affixed directly to the exit face  28 ′ of the diffuser  26 ′. Optical UV filters  38 ′ may be positioned between the secondary UV light sources  36 ′ and the phosphor-coated indicia  34 ′. The UV filters  38 ′ allow UV light of a predetermined wave length only to pass through. For example, a typical UV light wave length might be 365 nm. Thus, when energized, the UV light source  36 ′ may produce light within a wide range of wave lengths, however the filter  38 ′ will only allow light at the 365 nm wave length to pass through to the phosphor-coated indicia  34 ′. In some circumstances, this may be beneficial. Phosphor-coated indicia  34 ′ of differing compositions, and responsive to UV light in different wave lengths, may be applied in concert with different UV filters  38 ′ to achieve additional lighting effects. If the phosphor-coated indicia is selectively chosen so that its phosphor material is reactive to UV radiation at one wave length but not affected by UV light at another wave length, the multiple UV filters  38 ′ and their secondary UV light sources  36 ′ can be selectively energized to excite only portions of the phosphor-coated indicia  34 ′ at any given time. Thus, multiple expressions can be achieved through a single system. 
       FIG. 5  also illustrates the smooth dispersion of the light rays emanating from the primary light sources  22  by way of their projected beam patterns  40 ′. As illustrated here, the beam patterns  40 ′ are in the form of even, elliptical spreading which results in a smooth optical presentation to drivers traveling behind the automobile  10 . It will be appreciated, however, that other non-elliptical lighting patterns can be achieved by optimizing the design of the collector  24 ′ and diffuser  26 ′, and/or by incorporating a lens or reflector into the optical system. 
     In  FIG. 6 , a second alternative embodiment of the subject invention is illustrated in schematic form. For convenience, double prime (″) designations will be used with previously introduced reference numerals. As in previous embodiments, the CHMSL assembly  16 ″ includes a primary light source  22 ″ positioned adjacent a collector  24 ″ and diffuser  26 ″ having an exit face  28 ″. A UV light source  36 ″ is likewise provided. In this example, the phosphor-coated indicia  34 ″ is applied directly to the inner surface of the light transmissive screen  20 ″. Thus, the transparent plate  30  of the preceding example is again eliminated. To address the interchangeability issue, the light transmissive screen  20 ″ can be mounted with some form of interchange mechanism to permit convenient substitution for another light transmissive screen  20 ″ with differently formed phosphor-coated indicia  34 ″. A control circuit  42 ″ is shown electrically interconnecting the primary visible light source  22 ″ and the secondary UV light sources  36 ″ in the manner as previously described. 
     According to any one of the preceding embodiments, a method for selectively presenting lighted indicia from an automobile  10  can be accomplished. The method comprises the step of containing a primary visible light source  22 , a secondary ultraviolet light source  36  and a phosphor-coated indicia  34  within a UV impervious housing  18 . The phosphor-coated indicia  34  is irradiated with the ultraviolet light from the secondary UV light source  36  while the primary visible light source  22  is inactive. By this technique, the phosphor-coated indicia  34  is visible to observers outside through a light transmissive screen  20  incorporated into the housing  18 . A control circuit automatically de-energizes the secondary UV light source  36  in response to the primary visible light source being energized so that there is no conflict between the two lighting systems operating within a common housing  18 . The phosphor-coated indicia  34  is substantially invisible to observers whenever the primary light source  22  is active. Preferably, although not necessarily, the phosphor-coated indicia are mounted on a removable transparent plate  30  or on a removable light transmissive screen  20 ″ so that expressive ideas can be changed from time to time. The step of automatically de-energizing the secondary ultraviolet light source  36  is responsive to a brake-induced vehicle deceleration, such as occurs when a driver depresses the brake pedal. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, the various features and distinctions among the several embodiments are generally interchangeable one with another. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.