Light emitting diodes (LEDs) are an energy efficient, highly reliable technology that is finding considerable utility in replacing fluorescent lamps in many lighting applications. Fluorescent lamps have become a less desirable source for energy efficient lighting applications since they emit light in 360 degrees. This makes it hard to efficiently direct all of the emitted light to the intended usable area of the lighting application. However, while LEDs are more energy efficient, they present their own design challenges for lighting applications. Specifically, LEDs are point sources as opposed to continuous/extended sources of light. This concentration of point source light needs to be evenly dispersed and distributed across the intended usable area for the lighting application. In addition, since LEDs are point sources requiring dispersion in lighting applications, dispersed LED light will travel across a wide range of angles that will either be: (1) absorbed within the luminaire and create efficiency loss; (2) redirected out of the luminaire but beyond the intended usable area; (3) redirected out of the luminaire but unevenly distributed in the intended usable area, or (4) redirected out of the luminaire and evenly distributed across the intended usable area. Therefore, there are difficult design challenges to properly dispersing light from a row of LEDs into a useful and efficient light distribution. LED luminaire designs that fail to achieve even dispersion and distribution across the intended usable area, and fail to account for the wide range of angles for emitted light, will yield poor performance, including unacceptable glare and poor aesthetics in those lighting applications.
A need exists for a low cost luminaire configuration that efficiently redistributes the point source illumination from LEDs into a light output distribution superior to the inefficient distribution achieved with fluorescent lamps and existing LED luminaires. Specifically, there is a need for a new and more efficient luminaire that offers an even distribution of luminance across its luminous surface, evenly distributes light over a wide footprint below the luminaire, and for which the form factor and conformal geometry of the luminaire is similar to what was designed for traditional/conventional fluorescent lamps.
It would be desirable to have a minimally complex, low cost/economical means of providing for the distribution of point source light, for example an array of LEDs, from a luminaire intended for a general lighting application, wherein the physical structures and components of the luminaire are relatively easy to manufacture with low-cost materials and are relatively easily to assemble to create a relatively low cost, energy efficient and aesthetically pleasing functional luminaire.
In one aspect of the embodiments, a luminaire is disclosed comprising: a substrate having a length; a light redirecting assembly comprising: a clear, light transmissive, semi-rigid, flexible film extending the length of the substrate, a clear, light transmissive cover extending the length of the substrate and comprising: one or more locations at which the film may be held in place proximate to the cover and which holding allows the film to approximately conform to the shape of the cover; an air-filled cavity defined by the substrate and by the light redirecting assembly; a linear array of discrete light sources positioned so as to emit light into the cavity, wherein the array of discrete light sources is affixed to the surface of the substrate facing into the air-filled cavity and extends along the length of the substrate; an electronic control for activating and powering the discrete light sources to emit light; an electrical connection between the discrete light sources and the electronic control for activating and powering the discrete light sources, and wherein the surface of the clear, light transmissive, semi-rigid, flexible film facing into the air-filled cavity comprises: an array of optical relief structures extending into the air-filled cavity.
In a further aspect of the embodiments, the discrete light sources of the disclosed luminaire are light emitting diodes and the optical relief structures are selected from the following list of structures: V groove, isosceles triangular groove, right triangular groove, acute triangular groove, pyramid, square pyramid, square right pyramid, rectangular pyramid, rectangular right pyramid, rhombic pyramid, or polygonal pyramid. In addition, the optical relief structures may have at least two opposing sides and may have a base and may have angles between faces on the two opposite sides of the structures and the base of the structure that are different from each other, and those angles may vary from structure to structure over at least a portion of the surface of the film. In addition, the angles between the faces on the two opposite sides of a structure and the base of the structure may vary from structure to structure over at least a portion of the surface of the film. In addition, the dimensions of the sides of the bases of the structures may vary from structure to structure over at least a portion of the surface of the film. In addition, the heights of the optical relief structures may vary from structure to structure over at least a portion of the surface of the film. In addition, the heights of the optical relief structures may be between 5 and 200 microns, and most preferably between 20 and 40 microns. In addition, where the optical relief structures have a base with sides, the sides of the bases of the optical relief structures may be between 5 and 200 microns in length, and most preferably between 20 and 40 microns in length.
In a further aspect of the embodiments, the film of the luminaire may have surface topology facing into the cavity that comprises an array of grooves that are separated by ridges having triangular cross-sections, wherein in some sections of the surface topology the triangular cross-sections of the ridges have the shape of right triangles and in other sections of the surface topology the ridges have the shape of isosceles triangles. And in a still further aspect, two sections of the surface topology having ridges with cross-sections having the shape of right triangles may lie adjacent to and on opposite sides of the central axis of the film, and wherein the vertical sides of the right triangular cross-sections are oriented towards the central axis. In addition, the right triangular shapes of the cross-sections of the ridges may vary across the sections with the angles of the triangular shapes opposite their vertical sides and may increase with increasing distance from the central axis. Further, in addition to the sections of the surface topology having ridges with cross-sections having the shape of right triangles, there may be two additional sections of the surface topology having ridges with cross-sections having the shape of isosceles triangles which lie adjacent to the two sections having ridges with cross-sections having the shape of right triangles. In addition, the angles of the triangular shapes opposite their vertical sides may increase from 30 degrees to 50 degrees. In addition, the four sections of the surface topology may be equal in area and the cross-sections having the shape of isosceles triangles may have apex angles of 98 degrees. Where the optical relief structures are a series of grooves with triangular cross-sections, the heights of the triangular cross-sections of the grooves may be between 5 and 500 microns, or more preferably between 20 and 40 microns, and such heights may vary across at least a portion of the surface of the film; and the widths of the grooves may be between 5 and 200 microns, or more preferably, between 20 and 40 microns; and such widths may vary across at least a portion of the surface of the film.
In a further aspect of the embodiments, the shape of the cover of the disclosed luminaire may be that of half of a hollow cylinder and further, the edges of the cylindrical cover—along which the shape would be cut from a full hollow cylinder—may be attached to the substrate to define the air-filled cavity of the luminaire. Specifically, the shape of the cover of the disclosed luminaire may be one of the following: half of a hollow circular cylinder, half of a hollow elliptic cylinder, half of a hollow parabolic cylinder. In addition, the luminaire may further comprise a diffuse white reflector that is coated, adhered to, or attached to the surface of the substrate that faces into the air-filled cavity. In addition, the cover may incorporate a light diffusing material, which may be adhered or otherwise affixed to a surface of the light transmissive cover. In addition, the array of optical relief structures extending into the air-filled cavity may cover the entire surface of the clear, light transmissive, semi-rigid, flexible film.
The novel features of the aspects described herein are set forth with particularity in the appended claims. The aspects, however, both as to organization and methods of operation may be further understood by reference to the following description, taken in conjunction with the accompanying drawings.
We have now devised simple and relatively inexpensive luminaire designs that redistribute the light from a row of LEDs into a continuous bar of light of relatively uniform luminance and then disperses that light in a desirable distribution with a high energy efficiency.
The device 100 depicted in
The exemplary sawtooth topology 116 is but one example or means to describe the geometric structures intended to influence the reflection and transmission of light to achieve a preferred light distribution pattern. These geometric structures are sometimes referred to as optical relief structures or optics and are generally deployed in an array across the entire surface of the polymeric material. Or, as disclosed in U.S. Pat. No. 7,878,690, the array may be characterized as a microlens or prism lens array. Suitable optical relief structures may include V groove-, isosceles triangular groove-, right triangular groove-, acute triangular groove-, pyramid-, square pyramid-, square right pyramid, rectangular pyramid-, rectangular right pyramid-, rhombic pyramid-, or polygonal pyramid-like structures.
When light is emitted from LEDs 102 in luminaire 100, the light will strike one of the faces of the pyramidal protrusions. For example, as shown in
There is, however, a serious design consideration in the construction of luminaire 100. The three dimensional structure of cover 108 with its array of pyramidal protrusions 116 makes it extremely difficult if not impossible to extrusion mold a polymer into such a part because it may not release from the mold.
A flexible sheet with a surface topology similar to topography 336 of film 328 may optionally be adhered or otherwise affixed to the inner surface of cover 308 in lieu of utilizing some means of capturing film 328. The surface topology similar to 336 would, again, face inward into cavity 301.
A further embodiment of the invention may be explained with reference to
The configurations of the pyramidal structures that may be practically or cost effectively used on cover 108 or film 328 are constrained by the fabrication processes used to produce the cover or film. The angle δ between the faces of adjacent pyramids cannot be made to be too small because of the constraints of the diamond turning process used to fabricate the tooling used in the embossing or molding process. Acute pyramidal structures may be formed on the surface of cover 108 or film 328, but an inner surface with obtuse pyramidal structures cannot be practically produced by the embossing or compression molding techniques.
In embodiments similar to exemplary embodiments 100 and 300, it is often advantageous to vary the configurations of the pyramidal structures on the inner surface 110 of cover 108, or inner surface 330 of film 328, across the cross-sections shown in
In some embodiments of the invention sufficiently improved optical performance may be obtained by utilizing a flexible, but semi-rigid film similar to 328, but in this case the surface topology of the film has a profile that is unchanging along the an axis running the length of the luminaire (that is to say, along an axis analogous to axis A-A′ in
When viewed from the direction of
In embodiments having the grooved surface profiles on the inward facing surface of films similar to 328, it is often advantageous to vary the configurations of the triangular grooves on the inward facing surface (similar to 330) of the films across the cross-sections like those shown in
To fabricate a luminaire similar to embodiment 300 shown in
The profile 816 of surface 810 of cover layer 808 in embodiment 800 contains obtuse triangular structures that could not be produced in a film by embossing or compression molding. But, since the surface profile extends along only one axis of cover layer 808, this part may be produced by an extrusion process. Cover layer 848 may be a film with the embossed or compression molded surface topology 856 layered over cover layer 808. In other embodiments cover layers 808 and 848 may exchange places in the structure of a luminaire like luminaire 800. In such a case the outer cover layer (that has a surface topology like 816 in
Embodiments that use two semi-rigid films of clear, transparent material with two orthogonal sets of grooves to replace and function in a similar manner to rigid cover layers 808 and 848 and in which the semi-rigid films are captured by projections from a clear cover similar to 308 in embodiment 300 above are possible so long as the films' surface topologies are capable of being embossed or compression molded. That is to say, films in such embodiments cannot have sawtooth cross-sectional profiles that involve obtuse triangular structures or possibly very steep-sided acute triangular structures.
The embodiments described above are illustrative examples and it should not be construed that the present invention is limited to these particular embodiments. For example, although LED devices were used as examples of discrete light sources, other light emitting devices may be used. Further, although the orientation of components in the embodiments were described as being parallel to or running the length of other components, it should be understood that they need not be exactly parallel or running exactly the length, rather in a close range of being normal or substantially normal or in a close range of running the length. Further, various components and aspects described with reference to different embodiments are interchangeable among different embodiments, and are not limited to one particular embodiment. Thus, various changes and modifications may be effected by one skilled in the art without departing from the spirit or scope of the invention as defined in the appended claims.
The drawings illustrating the embodiments of this patent illustrate objects of greatly varying size. The relative sizes and numbers of various objects as portrayed in the drawings have been modified for the sake of clarity and completeness. Therefore, the relative size and number of objects in the drawings should not be taken as accurate in terms of size or extent relative to other objects.
While the present invention has been particularly shown and described with reference to example embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims and equivalents thereof. It is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive, reference being made to the appended claims and equivalents thereof rather than the foregoing description to indicate the scope of the invention.
This application is a continuation of U.S. application Ser. No. 16/421,422, filed May 23, 2019, allowed and expected to issue as U.S. Pat. No. 10,665,803 on May 19, 2020, which is a continuation of U.S. patent application Ser. No. 15/441,940, filed on Feb. 24, 2017, issued as U.S. Pat. No. 10,317,021, the disclosures of which are incorporated by reference herein their entireties for all purposes.
Number | Date | Country | |
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Parent | 16421422 | May 2019 | US |
Child | 16874929 | US | |
Parent | 15441940 | Feb 2017 | US |
Child | 16421422 | US |