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Researchers Submit Patent Application, "Face-Lit Waveguide Illumination Systems", for Approval

September 3, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventor VASYLYEV, SERGIY VICTOROVICH (Elk Grove, CA), filed on February 13, 2013, was made available online on August 21, 2014.

No assignee for this patent application has been made.

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to planar light emitting waveguides such planar plate or slab waveguides distributing light along the broad surface of the plate and emitting the distributed light from the broad-area plate surface. This invention also relates to an apparatus and method of inputting light into a planar waveguide through its face as opposed to edge-lit light guide panels where light is input through one of the waveguide edges. More particularly, this invention relates to panel luminaires, illuminated panel signs, illuminated window pane signs, front lights, backlights, lighting panels, LCD display backlights, computer screens, advertising displays, road signs, and the like, as well as to a method for redistributing light from a variety of light sources.

"Conventionally, light emitting devices employing a planar waveguide include an optically transmissive plate, a light source coupled to the plate's edge and a series of optical features distributed along a major surface of the plate for extracting light at predetermined locations of the surface.

"However, a number of applications exist where edges of the waveguide are not accessible or it is otherwise impractical to input light through an edge. Furthermore, many existing structural or artistic articles which can provide light guiding and distribution functions are not always readily transformable to edge-lit applications. Typical examples include framed glass windows of building facades and doors, storefront window panes, as well as various interior and exterior architectural features employing transparent glass or plastic panels.

"Other examples of common objects which could be used as planar waveguides but may not be suitable for light input from an edge include but are not limited to planar slabs of glass or transparent plastic which edges are roughened or sanded. In a yet further example, the edges of some transparent slabs or panels may be tapered making it difficult to input light from a relatively large source. The light input aperture of edges may also be too small compared to the size of the light source due to the insufficient thickness of the transparent slab or panel.

"It is therefore an object of this invention to provide an improved illumination system providing an efficient light input through a face of a planar waveguide as opposed to light input through an edge. It is another object of this invention to provide a convenient light injection into a planar waveguide, such as an existing window pane of a building, through its face, without having to penetrate into the waveguide's surface. It is yet another object of this invention to provide convenient light input in one area of a major surface of a planar waveguide and light extraction from the waveguide in another area of the surface. It is yet another object of this invention to provide an improved method of coupling light to a planar waveguide without having to access its edges and while substantially reducing or eliminating the unwanted light spillage due to the coupling. Other objects and advantages of this invention will be apparent to those skilled in the art from the following disclosure."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventor's summary information for this patent application: "Accordingly, the present invention is directed to face-lit planar waveguide illumination systems which may be employed to redistribute light emitted by a compact light source over a large area of the planar waveguide and re-emit at least a portion of the distributed light from a major surface of the waveguide. More particularly, this invention is directed to a system for injecting light into the face of a planar plate, slab or substrate of an optically transmissive material in one area and extracting at least some of the injected light from another area of the plate or substrate.

"The present invention solves a number of problems associated with light distribution and illumination using planar waveguides by providing a face-lit solution which is not hindered by the limitations of conventional edge-lit illumination devices requiring the access to waveguide edges or surface penetration for enabling light input.

"An advantage of the present system is to provide controlled light input trough a face of the planar waveguide in one location so that such light can be propagated along the waveguide in response to the optical transmission and a total internal reflection generally towards at least one well-defined direction and can then be extracted from another location of the waveguide along said direction.

"Light is injected into the planar waveguide by means of an elongated (linear) optical element attached to a face of the waveguide and optically coupled to said face.

"According to one aspect of the invention, light is input into a face or broad-are surface the planar waveguide non-invasively and without penetrating into the waveguide's body. According to another aspect of the invention, a linear configuration of the optical element allows for coupling light into the waveguide from a linear light source which may be represented by an elongated light-emitting element or a linear array of compact light-emitting elements. According to yet another aspect, the linear configuration of the light coupling optical element may also be used for injecting light into the waveguide from a discrete light source optically coupled to a terminal end of the optical element.

"In at least one embodiment, the invention features a planar optical waveguide exemplified by a portion of an optically transmissive window pane, a linear light coupling optical element attached to a planar face or major broad-area surface of the pane and a linear light source. The light source includes a strip light emitting diodes (LEDs) incorporated is a linear array. The linear LED array is positioned generally parallel to the longitudinal axis of linear optical element and is configured to illuminate the optical element with a beam of light. The linear optical element is optically coupled to the face of the window pane by means of a planar surface and by providing a good optical contact between the surface and the face of the window pane.

"The optical element is configured to inject light into the medium of the window pane at a sufficiently low out-of-plane angle permitting for the subsequent light propagation within by means of a total internal reflection from the opposing faces of the pane. According to an aspect of the present invention, the optical element injects light into the waveguide mode while directing the light beam towards a well-defined direction along the window pane so that the injected light can be mixed along the propagation path and then extracted at another location of the window pane.

"In at least one embodiment, the invention includes one or more light extracting features positioned along the prevailing path of light propagation in the waveguide. The light extracting features are configured to extract light from the waveguide and direct such light towards a surface perpendicular. According to an aspect of the invention, at least a portion of the extracted light may be directed away from the waveguide and towards a viewer thus providing conspicuous visibility of the light extracting features.

"In at least one embodiment, the invention includes a linear collimating element optically coupled to the light source. Various implementations of the collimating element include linear or axisymmetrical refractive lenses, TIR lenses, reflectors, concentrators, and any combinations thereof.

"Various implementation of the light coupling optical element include forming at least a part of the element from an elongated block of transparent material. In one implementation, the elongated block has a shape of a right-angle prism or wedge. In one implementation, the elongated block has at least one planar surface or at least one curvilinear surface. In one implementation, the elongated block has a triangular transversal cross-section. In one implementation, the elongated block has a trapezoidal transversal cross-section. In further implementations, the optical element has sharply asymmetrical and axisymmetrical configurations in a transversal cross-section. Various faces or surfaces of the optical element may be configured for refracting light and/or for reflecting light by means of a specular reflection or TIR.

"In at least one embodiment the light coupling optical element includes a strip of a film material laminated onto the face of the waveguide. Various implementations of such optical element include prismatic films, holographic films, diffractive films, and any other types of light turning films which may be used for suppressing the refraction at the waveguide surface or for injecting light into waveguide at angles allowing for TIR propagation.

"Various implementations of the face-lit waveguide illumination system include suitable housing components and means for blocking stray light.

"In at least one embodiment of the invention, the width of the linear optical element is defined by the thickness of the planar waveguide. According one specific implementation, the width of the optical contact area of the linear optical element with a major surface of the waveguide is approximately equal to or less than 2d/ {square root over (n.sup.2-1)}, where d is the thickness of the waveguide and n is the refractive index of the waveguide's medium. According to other specific implementations, the transversal width of the light coupling optical element is less than two times the thickness of the planar waveguide and more preferably, 1.8 times the thickness of a glass window pane.

"In at least one embodiment, the light source is selected from the group of light emitting elements including fluorescent lamps, linear arrays of light emitting diodes, incandescent lamps, cold-cathode or compact fluorescent lamps, halogen, mercury-vapor, sodium-vapor, metal halide, electroluminescent lamps or sources, field emission devices, and lasers.

"In at least one embodiment, the face-lit waveguide illumination system includes the light coupling optical element made from light transmitting material and having the shape of a linear rod or bar. Such rod or bar may have various cross-sections including but not limited to square, rectangular, triangular, pentagonal, hexagonal, octagonal, trapezoidal, circular, half-circular, and oval. The cross-section may also include circular segments or sectors.

"In at least one embodiment, the optical element includes an optically transmissive light turning or light redirecting film. Various implementations of such film include microstructured prismatic films, diffractive films, holographic films, and films with internal light redirecting structures.

"In at least one embodiment, the illumination system includes means for extracting light from the planar waveguide. In one implementation, the light extracting means include light scattering or light diffusing features. Such features may be embedded into the waveguide's body formed in a surface of the waveguide or externally attached to the waveguide surface. In other implementations, the light extracting means include a textured surface, indicia and or an image print.

"In at least one embodiment, the light coupling optical element may be configured with wave guiding properties. In different implementations, it may be formed by a relatively long elongated body of a light transmitting material or include one or more optical fibers.

"In at least one embodiment, the light coupling optical element is attached to the face of the waveguide by means of an intermediate film which may have a substantially larger area than the contact area of the optical element. In at least one embodiment, the optical element is attached either directly to the face of the waveguide or to the intermediate film or plate using an optically clear adhesive or encapsulant.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

"The invention will be more fully understood by reference to the following drawings which are for illustrative purposes only:

"FIG. 1 is a schematic perspective view of a face-lit waveguide illumination system, according to at least one embodiment of the present invention.

"FIG. 2 is a schematic cross-sectional view and raytracing of a face-lit waveguide illumination system portion, showing a wedge-shaped light coupling optical element, according to at least one embodiment of the present invention.

"FIG. 3 is a schematic cross-sectional view and raytracing of a face-lit waveguide illumination system portion, showing a tapered light coupling optical element, according to at least one embodiment of the present invention.

"FIG. 4 is a schematic cross-sectional view and raytracing of a face-lit waveguide illumination system portion, showing a symmetrical configuration of a light coupling optical element, according to at least one embodiment of the present invention.

"FIG. 5 is a schematic cross-sectional view and raytracing of a face-lit waveguide illumination system portion, showing a prismatic film laminated onto a face of a window pane, according to at least one embodiment of the present invention.

"FIG. 6 is a schematic view of a face-lit waveguide illumination system portion, showing an exemplary arrangement of linear light emitting and light coupling elements, according to at least one embodiment of the present invention.

"FIG. 7 is a schematic view of a face-lit waveguide illumination system portion, showing a layered light coupling element including internal corrugated boundary between two layers, according to at least one embodiment of the present invention.

"FIG. 8 is a schematic view of a face-lit waveguide illumination system portion, showing an optical element having curvilinear reflective surfaces, according to at least one embodiment of the present invention.

"FIG. 9 is a schematic cross-sectional view and raytracing of a face-lit waveguide illumination system, showing a reflective surface extending parallel to a face of a window pane, according to at least one embodiment of the present invention.

"FIG. 10 is a schematic cross-sectional view and raytracing of a face-lit waveguide illumination system, showing a light source optically coupled to an edge of a planar light coupling optical element, according to at least one embodiment of the present invention.

"FIG. 11 is a schematic perspective view and raytracing of a face-lit waveguide illumination system, showing a planar light coupling optical element attached to a face of a window pane, according to at least one embodiment of the present invention.

"FIG. 12 is a schematic perspective view and raytracing of a face-lit waveguide illumination system portion, showing a plurality of optically transmissive rods or bars attached to a face of a planar slab waveguide, according to at least one embodiment of the present invention.

"FIG. 13 is a schematic cross-sectional view of a face-lit waveguide illumination system portion, illustrating light injection into a thin planar waveguide, according to at least one embodiment of the present invention.

"FIG. 14 is a schematic view of a face-lit waveguide illumination system portion, illustrating an exemplary method of attaching a light coupling optical element to a face of a planar waveguide, according to at least one embodiment of the present invention.

"FIG. 15A through FIG. 15F, illustrate various exemplary configurations of a linear optical element, according to at least some embodiments of the present invention.

"FIG. 16 illustrate an exemplary arrangement of optical elements and light sources with respect to a face of a window pane, according to at least one embodiment of the present invention.

"FIG. 17 is a schematic perspective view and raytracing of a face-lit waveguide illumination system portion, showing a plurality of optical fibers attached to a face of a planar slab waveguide, according to at least one embodiment of the present invention."

For additional information on this patent application, see: VASYLYEV, SERGIY VICTOROVICH. Face-Lit Waveguide Illumination Systems. Filed February 13, 2013 and posted August 21, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=3753&p=76&f=G&l=50&d=PG01&S1=20140814.PD.&OS=PD/20140814&RS=PD/20140814

Keywords for this news article include: Patents, Electronics, Light-emitting Diode.

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Source: Electronics Newsweekly


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