Patent Publication Number: US-10310156-B2

Title: Visible light generated using UV light source

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to U.S. patent application Ser. No. 12/491,937 filed on Jun. 25, 2009 entitled UV GENERATED VISIBLE LIGHT SOURCE, and is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1.0 Field of the Invention 
     The invention is directed to a method and apparatus for generating visible light and, more particularly, to a method and apparatus for generating visible light using an ultraviolet laser, or similar UV light source and a UV light reactive material such as quantum dot material, for example. 
     2.0 Related Art 
     Lighting sources in today&#39;s world, such as lamps, flashlights or general light bulbs, for example, use traditional techniques for generating light that might involve an incandescent bulb or in newer versions, light emitting diodes (LEDs), compact fluorescents, and the like. These techniques have several characteristics that may be limiting or undesirable. For example, the power requirement may be relatively high and the bulbs or diodes may have a relatively short life expectation due to being damaged in normal use, or by burn-out. Furthermore, some may have complicated structures and use dangerous chemicals such as compact fluorescents. Moreover, the amount of lumens produced may be relatively limited. 
     By far the most common application of fluorescence in daily life is in the fluorescent light bulb, of which there are more than 1.5 billion operating in the United States. Fluorescent light stands in contrast to incandescent, or heat-producing, electrical light. First developed successfully by Thomas Edison (1847-1931) in 1879, the incandescent lamp quite literally transformed human life, making possible a degree of activity after dark that would have been impractical in the age of gas lamps. Yet, incandescent lighting is highly inefficient compared to fluorescent light: in an incandescent bulb, fully 90% of the energy output is wasted on heat, which comes through the infrared region. 
     A fluorescent bulb consuming the same amount of power as an incandescent bulb will produce about three to five times more light, and it does this by using a phosphor, a chemical that glows when exposed to electromagnetic energy. (The term “phosphor” should not be confused with phosphorescence: phosphors are used in both fluorescent and phosphorescent applications.) The phosphor, which typically coats the inside surface of a fluorescent lamp, absorbs ultraviolet light emitted by excited mercury atoms. It then re-emits the ultraviolet light, but at longer wave-lengths, as visible light. Thanks to the phosphor, a fluorescent lamp gives off much more light than an incandescent one, and does so without producing much heat. 
     Accordingly, alternative techniques for efficiently producing reliable, safe and bright visible light cost effectively would be a welcomed advancement in the light producing industry. 
     SUMMARY OF THE INVENTION 
     The invention meets the foregoing need and includes a method and apparatus to cost effectively and reliably produce visible light from a UV light source. In one aspect, the invention includes producing visible light by generally directing UV light onto a UV light reactive surface to produce visible light. This surface may comprise a reflective surface. 
     Accordingly, in another aspect of the invention, an apparatus for generating visible light is disclosed. The apparatus includes an ultraviolet (UV) light source configured to emit UV light, a UV light scattering mechanism to scatter the UV light, and a UV light reactive composition that reacts to the scattered UV light produce visible light. 
     According to still another aspect of the invention, a method for producing visible light from ultraviolet (UV) light is provided. The method including emitting a beam of UV light from a UV light source, and scattering the beam onto a UV light reactive composition to produce visible light. 
     In another aspect, an apparatus for generating visible light is provided that includes at least one ultraviolet (UV) light source configured to emit UV light and a UV reactive composition that reacts to the UV light to produce visible light. 
     In another aspect, an apparatus for generating visible light is provide that includes at least one ultraviolet (UV) light source configured to emit UV light and a quantum dots composition that reacts to the UV light to produce visible light. 
     In yet another aspect, a method for producing visible light from ultraviolet (UV) light includes emitting UV light from a UV light source and directing the beam onto a UV light reactive composition to produce visible light. 
     Additional features, advantages, and embodiments of the invention may be set forth or apparent from consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that both the foregoing summary of the invention and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the detailed description serve to explain the principles of the invention. No attempt is made to show structural details of the invention in more detail than may be necessary for a fundamental understanding of the invention and the various ways in which it may be practiced. In the drawings: 
         FIG. 1A  is an illustration of an embodiment for a visible light generating device, constructed according to principles of the invention; 
         FIG. 1B  is an exploded view of the area denoted by “ 1 B” of  FIG. 1A ; 
         FIG. 1C  is another illustration of the exploded view of the area denoted as “ 1 B” of  FIG. 1A , showing the functional characteristics of a reflected lased UV beam on a UV light reactive composition surface, according to principles of the invention; 
         FIG. 1D  is an illustration of another embodiment for a visible light generating device, constructed according to principles of the invention; 
         FIG. 1E  is an illustration of another embodiment for a visible light generating device, constructed according to principles of the invention; 
         FIG. 2  is an end on view of the visible light generating device of  FIG. 1A , viewed from the scattering surface end; 
         FIG. 3  is a flow diagram showing an exemplary process performed according to principles of the invention; 
         FIG. 4A  is a side view,  FIG. 4B  is a top view, and  FIG. 4C  is a side view of an exemplary visible light apparatus, constructed according to principles of the invention; and 
         FIG. 5  is a side view of another exemplary visible light apparatus, constructed according to principles of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It is understood that the invention is not limited to the particular methodology, protocols, etc., described herein, as these may vary as the skilled artisan will recognize. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to limit the scope of the invention. It is also to be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include the plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to “an address” is a reference to one or more addresses and equivalents thereof known to those skilled in the art. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the invention pertains. The embodiments of the invention and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and examples that are described and/or illustrated in the accompanying drawings and detailed in the following description. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale, and features of one embodiment may be employed with other embodiments as the skilled artisan would recognize, even if not explicitly stated herein. Descriptions of well-known components and processing techniques may be omitted so as to not unnecessarily obscure the embodiments of the invention. The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those of skill in the art to practice the embodiments of the invention. Accordingly, the examples and embodiments herein should not be construed as limiting the scope of the invention, which is defined solely by the appended claims and applicable law. Moreover, it is noted that like reference numerals reference similar parts throughout the several views of the drawings. As used herein, visible light is generally defined as light discernable to a human eye. However, the invention may have other applications which generally are apparent from the disclosure. 
       FIG. 1A  is an illustration of an embodiment for a visible light generating device, constructed according to principles of the invention, general denoted by reference numeral  100 . The visible light generating device  100  includes a body  105  having a first portion  110  and a second portion  115 , the second portion  115  may be configured in a generally cylinder shape. An ultraviolet (UV) laser  125  may be used as an initial source of UV light and may be configured to emit a beam “B” of lased UV light in the UV light spectrum range along the extent of the second portion  115 . The UV laser  125  may be a low cost blue diode version and/or a blue laser that produces a beam having a wavelength between about 360 and about 480 nm, for example. The UV laser  125  is an example of a coherent light source. The UV laser  125  may be permanently or removably coupled to the first portion  110 , or alternatively, permanently or removably coupled to the second portion  115 , as long as the UV laser is configured to emit a beam “B” generally along the horizontal axis (given the orientation as shown in  FIG. 1A ) of the second portion, and aligned to project the beam onto a scattering mechanism, such as scattering surface  140 . 
     The first portion  110  may be configured with connecting mechanisms  135 , which are shown in  FIG. 1A  as threads, to attach the visible light generating device  100  to a fixture such as a standard household light socket, flashlight, or other permanent or mobile light fixture. Other types of connecting mechanisms may be employed depending on the application, such as a flange mount, for example. Electrical connectivity may connect the UV laser  125  to any control electronics  130 , as necessary, or connect  137  to a power source (not shown) such as a battery, AC power or the like. The control electronics  130  and the UV laser  125  may be a unified component in some embodiments. 
     The second portion  115  may be configured generally in a cylindrical shape with a plurality or series of circumferential grooves  120  around the outer circumference of the second portion  115 . In a preferred embodiment, the second portion  115  may constructed as a barrel shaped solid plastic structure suitable for passing UV light and/or visible light, or may be constructed from or include other UV light and/or visible light passing material. The grooves  120  may be layered (or alternatively, impregnated) oil at least one surface with a UV light reactive composition that emits visible light when excited by a UV laser. Such UV light reactive composition may include phosphorous or a phosphorous composition, aluminum or an aluminum composition, compositions that include these elements, or similar compounds such that under exposure to UV laser light produces visible light, and/or other reflective compositions. 
     These aforementioned UV fluorescent material, or luminescent material that react to UV light, may be obtained from several sources; one example is MiniScience Corporation of Clifton, N.J. The luminescent material may also be obtained via an on-line website at the ChemicalStore&lt;dot&gt; com, where their collection of luminescent materials products is currently known as their Luminescent Materials Collection. 
     The UV light reactive composition may also comprise quantum dot material. A quantum dot generally includes a semiconductor material whose excitons are confined in all three spatial dimensions. As a result they typically have properties that are between those of bulk semiconductors and those of discrete molecules. Quantum dots may require very little power. Several techniques may be employed to construct quantum dots, as is generally known in the industry. In general quantum dots, quantum wells and quantum wires may be grown by advanced epitaxial techniques in nanocrystals produced by chemical methods or by ion implantation, or by lithographic techniques. Large quantities of quantum dots may be synthesized via colloidal synthesis. Collodial synthesis is a relatively low cost technique and is among the least toxic techniques. Self-assembled quantum dots may be produced between about 10 and 50 nm in size, but can vary. 
     The second portion  115  may also include a UV light scattering surface  140 . The UV light scattering surface may be configured to reflect and scatter a UV laser beam “B” backward into the “barrel” of the second portion  115 .  FIG. 2  is an end on view of the light generating device viewed from the scattering surface end. The inner surface of the scattering surface  140  may include a series of circular grooves  205 , similar to the circumferential grooves  120  along the length of the barrel in the second portion  115 , but the circular grooves  205  may be formed in a plane oriented substantially perpendicular to the beam “B.” The circular scattering grooves  140  may have angles and characteristics that scatter a UV beam backward into the barrel of the second portion  115 . The angled surfaces of the circular scattering grooves  140  may be layered or impregnated with a UV light reflecting material to reflect and scatter the beam “B,” in suitable angles to strike along the barrel of the second portion  115 , as shown by reflected beams  145 . In other embodiments, other geometric patterns may be employed other than the circular pattern for the grooves as shown in  FIG. 2 . 
       FIG. 1B  is an exploded view of the area denoted by “ 1 B” of  FIG. 1A . The exploded view “ 1 B,” illustrates the general configuration of a groove  120  with a front face  150  and a back face  155  forming a groove. The area denoted “C” is an open area of a groove formed between the front face  150  and the back face  155 . The angle “y” formed between the front face  155  and the reference line  160  (the reference line  160  is aligned along the outermost peaks of the grooves  120  along the extent of the second portion  115 ) forms an angle of about 30 degrees, but may vary. The front face  150  may be layered or impregnated with the UV light reactive composition that emits visible light when excited by a UV laser, as described previously. 
       FIG. 1C  is another illustration of the exploded view of the area denoted as “ 1 B” of  FIG. 1A , showing the functional characteristics of a reflected lased UV beam on a UV light reactive composition surface, according to principles of the invention.  FIG. 1C  shows a front face  150  and a back face  155  (there are a plurality of front faces and a plurality of back faces formed along the second portion  115 ) with a reflected beam of lased UV light  145  striking the front face  150 . Front face  150  comprises a UV light reactive composition  152  surface (such as an aluminum and/or phosphorus material, reflective compositions, or the like) which may be a film, coating, layered application, or impregnation of one or more of the groove forming surface  150 . As a result, the electrons of the UV light reactive composition surface are sufficiently excited to cause emission of visible light from the front face  150 , principally exiting from the front face  150  as visible light  147 . In particular, when the reflected UV beam strikes any of the front faces, the UV beam excites the electrons of the phosphorus/aluminum layer to a higher state and subsequently emits a photon when returning to a lower state. In some applications, the UV light reactive composition  152  may be of exceedingly thin thickness, perhaps to the atomic or molecular level. Emitted visible light may emit in any direction relative to the UV light reactive composition. 
     Since there is a plurality of scattering grooves  140 , the UV laser beam “B” may be reflected and scattered generally uniformly back into the barrel of the second portion  115  so that UV lased light strikes a great multitude of locations on the plurality of front faces  150  on the plurality of grooves  120  around the entire circumference of the second portion  115 . As a result, a relatively intense flood of visible light  147  about the visible light generating device  100  may be produced suitable for harnessing and use in many applications that might require a visible light source, such as flashlights, room lights, car lights, street lights, electronic devices, and so forth. 
     The visible light generating device  100  may be formed as one solid piece of translucent or transparent (to UV) plastic or other suitable material, thus creating a very environmentally resistant device, such as being nearly impervious to moisture. The UV laser  125  may be fabricated as a quite rugged component resistant to tough physical demand including shock, vibration, temperature extremes, pressure changes, and the like. The power demand may also be quite low. The amount of visible light output may be related to the power of the UV laser employed and the efficiency of the UV light reactive composition, but a very high visible light output may be achieved with a suitably chosen combination. 
     In another aspect, portions of the scattering surface  140  also may be layered or impregnated with the UV light reactive composition, as described above, to emit visible light. In this dual mode embodiment, the scattering surface  140  acts both to reflect and scatter UV light back into the barrel of the second portion  115  and may also act to emit visible light, itself. 
     The second portion  115  barrel shape may be made from transparent or translucent plastic or similar UV light passing material. The barrel end (such as scattering surface  140 ) may be made of the same type of plastic or similar light passing material, and also has grooves in a circular pattern on the surface. Preferably, the first portion  110  may be made of the same material as the second portion  115 , but the first portion  110  may be made from different materials, if an application warrants this difference. 
       FIG. 1D  is an illustration of another embodiment for a visible light generating device, constructed according to principles of the invention, generally designated as reference numeral  200 . The visible light generating device  200  of  FIG. 1D  is similar to the visible light generating device of  FIG. 1A  except that the UV light source is a UV light emitting diode (LED)  225 . The UV light emitting diode (LED)  225  is an example of a non-coherent light source. 
       FIG. 1E  is an illustration of another embodiment of a visible light generating device, constructed according to principles of the invention, generally denoted by reference numeral  300 . The embodiment of  FIG. 1E  may be similar to the embodiment of  FIG. 1A , but with some differences. The visible light generating device  300  includes a body  303  having a first portion  10  and a second portion  315 , the second portion  315  may be configured in a generally cylinder shape, having an outer surface  310 . The outer surface  310  may be a surface that forms the outermost surface of the second portion  315 , having a circumference generally around the cylinder of the second portion. An end portion  335  may be removably attached, such as by threads, or permanently attached to the second portion  315 . The end portion  335  may be constructed with a scattering mechanism such as scattering grooves  340  formed on at least one of its surfaces, in a manner similar to  FIG. 2 . 
     Still referring to  FIG. 1E , the second portion  315  may be constructed with a hollow interior  330 , which may be constructed with a UV light scattering mechanism, such as scattering grooves  320 , arranged along the inner surface if the second portion  315 . In one aspect, the end portion  315  may be removable to permit access to the hollow interior  330 , such as for application of the UV light reactive composition to the inner surface, i.e., on the scattering mechanism such as one or more scattering grooves  320  of the hollow interior  330  during manufacturing, for example, if the UV light reactive composition being employed requires interior surface application. 
     A UV light source  305 , such as a UV laser or UV LED, which may be used as an initial source of light and may be configured to emit a beam “B” of UV light in the UV light spectrum range along the extent of the second portion  315 . The UV light source  305  may be a low cost blue diode version and/or a blue laser that produces a beam having a wavelength between about 360 and about 480 nm, for example. A UV laser may be an example of a coherent light source. The UV light source  305  may be permanently or removably coupled to the first portion  110 , or alternatively, permanently or removably coupled to the second portion  315 , as long as the UV light source  305  is configured to emit a beam “B” generally along a horizontal axis (given the orientation as shown in  FIG. 1E ) of the second portion  315 , and aligned to project the beam “B” onto a UV light scattering mechanism, such as scattering mechanism  340 . The beam “B” may also contact the scattering grooves  320 , at least in part, depending in part on the characteristics of the UV light source  305  employed. 
     The second portion  315  may be constructed as a barrel shaped solid plastic structure suitable for passing UV light and/or visible light, or may be constructed from or include other suitable light passing material. The scattering grooves  320  within the hollow interior  330  (as well as scattering mechanism  340 ) may be layered, deposited, or alternatively, impregnated on at least one angled surface of one or more scattering grooves  320  with a UV light reactive composition that emits visible light when excited by a UV light source, as described previously. Alternatively, some of the UV light reactive compositions may be applied as a film. The UV light scattering mechanism  340  may be configured to reflect and scatter a UV laser beam “B” backward into the “barrel” of the second portion  315 . The scattering mechanism  340  may include a series of circular grooves, similar to grooves  205  and reflective surface  120  ( FIG. 2 ), either on an inner or an outer surface of end portion  335 . The circular scattering mechanism  340  grooves  140  may have angles and characteristics that scatter a UV beam backward into the hollow interior  330  of the second portion  315 . The visible light producing principles of the scattering mechanisms such as scattering grooves  320  has been described previously in relation to  FIG. 1B . The reference to  FIG. 1B  in  FIG. 1E  is in reference to the principles taught in  FIG. 1B , since the orientation of the grooves in  FIG. 1B  may be somewhat different when used as part of  FIG. 1E . 
     The light source  125  or  315  may be either a coherent UV light source or a non-coherent UV light source. A UV laser may be an example of a coherent UV light source. A UV diode or UV LED may be an example of a non-coherent light source.  FIG. 3  is a flow diagram showing an exemplary process performed according to principles of the invention, starting at step  300 . At step  305 , a UV beam may be produced, perhaps using a low powered blue laser or UV LED, for example. The light may be coherent or incoherent. At step  310 , the UV beam may be scattered and directed towards UV light reactive surfaces or compositions (such as described in relation to  FIG. 1A , for example). (In some applications, the scattering might not be needed, or at least be limited; rather, the beam may be directed directly towards the reactive surface). At step  315 , the UV light reactive surfaces or compositions may be excited by the UV beam. At step  320 , the excited UV light reactive surfaces or compositions may emit visible light. At optional step  325 , the visible light may be focused as necessary for a given application. At step  330 , the process exits/stops. 
     The process of  FIG. 3  may used in conjunction with a commercial product such as a flashlight, lamp, ceiling light, decorative light, electronic display, or the like. The process and associated device provides considerable visible light with use of minimal power. The amount of visible light may be related to the size/power of the UV light source and/or related to the amount of UV light reactive composition utilized for excitation by the UV light source. The principles herein include providing for a light source at a first wave length (e.g., UV wavelength) to be converted to light at a second wavelength (e.g., visible light wavelength). Moreover, in some applications, the UV fluorescent material may include phosphorus and at least one alkaline earth metal selected from among magnesium, strontium, calcium and barium to proved different colors of visible light. 
       FIG. 4A  is a side view,  FIG. 4B  is a top view, and  FIG. 4C  is a side view of an exemplary visible light apparatus, constructed according to principles of the invention, generally denoted by reference numeral  400 . The visible light apparatus  400  may be configured as a planar light type light  405  that may be configured in a size suitable for ceiling installation, for example, perhaps in a office environment, home, business and the like. Planar lights typically are available in various sizes to fit pre-existing square or rectangular frames or inserts in walls and or ceilings. Other configurations and sizes are contemplated by the invention and not limited to the orientations and dimensions shown in  FIGS. 4A-5 . 
     The planar type light may have multiple surfaces, first surface  403 , second surface  430   a,  third surface  430   b,  and fourth surface  425 . Moreover, the planar type light may include additional surfaces  420  comprising a UV light reactive composition such as a quantum dot material, phosphorus and/or aluminum material, for example. 
     In one aspect, surfaces  420  may be encased within a plastic body  415  or similar material that has the characteristic of passing UV light. One or more UV light sources  410   a,    410   b  may be configured to provide UV light into the interior portion of the planar type light  405 . Inner surfaces  430   a,    430   b  and  425  may be configured to reflect the UV light onto the surfaces  420 . These inner surfaces  430   a,    430   b  and  425  may comprise a type of UV light mirror, or reflecting mechanism. The UV light may interact with the surfaces  420  comprising a UV light reactive composition to generate visible light. The one or more UV light sources  410   a,    410   b  may be powered as appropriate from an external or internal power source (not shown). The planar light may be configured to be wired in a common manner similar to fluorescent or incandescent lights. 
       FIG. 5  is a side view of another exemplary visible light apparatus, constructed according to principles of the invention, generally denoted by reference numeral  500 . This visible light apparatus is similar to the exemplary visible light apparatus of  FIG. 4A-4C , except the apparatus  500  is configured to produce light in substantially two directions perpendicular to a horizontal axis  445  of the light apparatus  500 ; whereas light apparatus  400  is configured to produce light in substantially one direction perpendicular to the corresponding horizontal axis. It should be understood that the “horizontal axis” is in reference to  FIG. 5 , and is not meant to limit the orientation of the exemplary visible light apparatus in practice. In one aspect, apparatus  500  may be viewed logically as two light apparatuses  400  of  FIGS. 4A-4C  configured “back to back.” Light apparatus  500  may be configured as one unit and/or two versions of light apparatuses  400  combined. In the light apparatus  500 , a plurality of UV light sources  430   a - 430   d  may be employed. The surfaces  455 ,  456  may be configured as a mirror or reflecting surfaces for reflecting UV light. 
     In certain applications, in the light apparatus  400 ,  500 , the UV light source  410   a,    410   b,    410   c,    410   d  may be aligned to direct emitted UV light onto the mirrored surfaces  403 ,  430   a,    430   b,    425 , into the interior portion of the apparatuses  400 ,  500  and/or on to the surface  420  in varying degrees. In some applications, one or more UV light source  410   a - 410   d  may be aligned differently to direct the emitted UV light at different angles. Moreover, employing different characteristics of quantum dot materials such as the size of the quantum dots, for example, may provide different visible light output. For instance, larger quantum dots may have greater spectrum shift towards red light compared to smaller dots. 
     Several publications are available that may provide a general description for Quantum Dot technology including for example: “Semiconductor Nanocrystal Quantum Dots: Synthesis, Assembly, Spectroscopy and Applications,” Andrey Rogach, Springer (Aug. 15, 2008); “Quantum Wells, Wires and Dots: Theoretical and Computational Physics of Semiconductor Nanostructures, Paul Harrison,” Wiley-Interscience (Sep. 12, 2005); “The Quantum Dot: A Journey into the Future of Microelectronics,” Richard Turton, Oxford University Press, USA; Later Printing edition (May 15, 2009), each of which are incorporated by reference herein. 
     While the invention has been described in terms of exemplary embodiments, those skilled in the art will recognize that the invention can be practiced with modifications in the spirit and scope of the appended claims. These examples given above are merely illustrative and are not meant to be an exhaustive list of all possible designs, embodiments, applications or modifications of the invention.