SOLID STATE LIGHT WITH OPTICAL GUIDE AND INTEGRATED THERMAL GUIDE
A solid state light having a solid state light source such as LEDs, and optical guide, and a thermal guide. The optical guide is coupled to the light source for receiving and distributing light from the light source, and the thermal guide is integrated with the optical guide for providing thermal conduction from the solid state light source and dissipating heat through convection for cooling the light.
Latest 3M INNOVATIVE PROPERTIES COMPANY Patents:
The energy efficiency of lighting has become an important consideration in industrial, consumer, and architectural lighting applications. With the advances in solid state light technology, light emitting diodes (LEDs) have become more energy efficient than fluorescent lights. Further, the marketplace has a large established fixture base for Edison, fluorescent and high intensity discharge lights. These types of applications present a significant technical challenge for LEDs due to their inherent point source nature, and the need to operate the LEDs at relatively low temperatures. Today there are many solutions addressing these issues, including fans, thermal sinks, heat pipes and the like. However, these approaches limit the applications by adding complexity, cost, efficiency loss, added failure modes, and an undesirable form factor. The need remains to find a solution that can provide optical and efficiency benefits, at attractive manufacturing costs and design.
SUMMARYA light, consistent with the present invention, includes a light source, an optical guide, and a thermal guide. The optical guide is coupled to the light source for receiving and distributing light from the light source, and the thermal guide is integrated with the optical guide for providing thermal conduction from the light source for cooling the light.
The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, explain the advantages and principles of the invention. In the drawings,
Thermal guide 18 is integrated with optical guide 16 in order to draw heat from solid state light source 14 through conduction and dissipate the heat through convection to cool light 10 and to efficiently utilize both area and volume for the cooling. Thermal guide 18 includes heat acquisition, heat spreading, and heat dissipation zones or elements in order to cool the light. Through integration of the optical and thermal guides, embodiments of this invention overcome many of the limitations of current solid state light concepts such as those identified above.
Solid state light source 14 can be implemented with, for example, LEDs, organic light emitting diodes (OLEDs), or other solid state light sources. Certain embodiments can provide for uniformly distributed light from the solid state light source. Alternatively, lenses can be used to focus the emitted light. For example, in certain embodiments the light can produce a cone or curtain of light. The lenses could have air permeability for cooling and can include Fresnel lenses, prismatic structures, or lenslet structures. The solid state light sources can emit light of various colors for decorative or other lighting effects. Solid state light source 14 is electrically connected with power circuit 12, which can include a flexible circuit or other circuitry for powering the solid state light source. The circuitry to power the light source can include dimming circuitry and electronics to control frequency shifting or color shifting components that help produce a more desirable light, and an example of such electronics are described in U.S. patent application Ser. No. 12/137667, entitled “AC Illumination Apparatus with Amplitude Partitioning,” and filed Jun. 12, 2008, which is incorporated herein by reference as if fully set forth.
Optical guide 16 can be implemented with, for example, a transparent or translucent material capable of receiving light from the solid state light source and emitting the light. For example, optical guide 16 preferably is made of an optically suitable material such as polycarbonate, polyacrylates such as polymethyl methacrylate, polystyrene, glass, or any number of different plastic materials having relatively high refractive indexes. The optical guide can be configured in a variety of shapes such as a bulb, sphere, cylinder, cube, sheet, or other shape. Furthermore, the optical guide can include a matrix material that can contain light frequency shifting chromaphores to obtain a more desirable color rendering index, and examples of matrix stabilized dyes are described in U.S. Pat. No. 5,387,458, which is incorporated herein by reference as if fully set forth.
Thermal guide 18 can be implemented with a material capable of conducting heat from the solid state light source and dissipating the heat. For example, the thermal guide is preferably comprised of a material with a thermal conductivity from about 1 W/(m-K) to 1000 W/(m-K), and more preferably from 10 W/(m-K) to 1000 W/(m-K), and most preferable from 100 W/(m-K) to 1000 W/(m-K). The thermal guide draws heat from the solid state light source through conduction and dissipates heat into air through convection. Optionally, components of the thermal guide can include heat pipes. The thermal guide is integrated with the optical guide, meaning that the thermal guide is in sufficient contact, directly or indirectly, with the solid state light source in order to conduct and dissipate heat from the solid state light source for the light to function. For example, the thermal guide can draw heat from the solid state light sources to maintain the light sources cool enough to function as intended. The thermal guide can be directly in physical contact with the solid state light sources or indirectly in contact with them such as through a ring or other components upon which the solid state light sources are mounted. The thermal guide can also be in physical contact with the optical guide, either directly or indirectly through other components. Alternatively, the thermal guide need not be in physical contact with the optical guide, provided that the thermal guide can conduct sufficient heat from the solid state light sources in order for the light to function. Therefore, the thermal guide resides either co-extensively proximate at least a portion or preferably a majority of the area of the optical guide, or the thermal guide resides within at least a portion or preferably a majority of the volume of the optical guide in the case of a bulb, sphere or other three dimensional shape having an interior volume.
The thermal guide can include thermal conductive enhancements such as metal coatings or layers, or conductive particles, to help conduct the heat generated by the solid state light sources into and along the thermal guide. Further, the thermal guide can have convective thermal enhancements such as fins and microstructures to increase the convective heat transfer coefficient. The thermal guide can also have optical enhancements in order to enhance the light output of the optical guide. For example, the thermal guide can be formed from a reflective material or a material modified to have a reflective surface such as white paint, a polished surface, or a thin reflective material on its surface.
For lights 20 and 30, the optical guide and co-extensive thermal guide can be configured in a variety of shapes, aside from planar. For example, they can be formed in a circle, spiral, or a non-planar shape for decorative or other lighting effects. The optical guide can be formed from, for example, polycarbonate, polyacrylates such as polymethyl methacrylate, polystyrene, glass, or any number of different plastic materials having relatively high refractive indexes. The co-extensive thermal guides can be formed, for example, as a metallic coating on the optical guide.
A base 44 is configured to connect to a power supply, and it can include a power circuit for providing the required voltage and current from the power supply to drive the solid state light sources. Base 44 can be implemented with, for example, an Edison base for use with conventional light bulb sockets or a base for use with conventional fluorescent light fixture connections. Air passages 56 and 58 are provided between optical guide 52 and base 44 to provide free convection across thermal guide 54 through an air passage 60.
In this exemplary embodiment, the thermal guide is implemented with metallic fins 54, 62, and 64, as illustrated in
The exterior portion of light 42 can be used to distribute and emit light from the solid state light sources, and the interior portion of light 42 is used for cooling the thermal guide and solid state light sources. Optical guide 52 can be formed in a bulb shape, as represented in
As shown in
The solid state light sources can be mounted on ring portion 162 in a manner similar to the LEDs mounted on heat spreader ring 46. Cooling fins of a thermal guide, such as the fins described above, can be thermally connected to sections 164, 166, 168, and 170 such as through soldering, conductive epoxy, clips, or in other ways. In that manner, heat spreader 160 with the mounting features effectively becomes part of the thermal guide and can be easily manufactured from a sheet of material. Four triangularly shaped sections 164, 166, 168, and 170 are shown for illustrative purposes only. More or fewer features can be used, and the features can have various shapes, depending upon, for example, a configuration of the cooling fins to which they are to be connected.
Claims
1. A light with integrated light and thermal guides, comprising:
- a light source;
- a light guide coupled to the light source for receiving and distributing light from the light source, wherein the light is transported within the light guide until the light exits from a surface of the light guide; and
- a thermal guide integrated with the light guide for providing thermal conduction from the light source for cooling the light, wherein the thermal guide comprises a solid material capable of conducting heat from the light source and dissipating the heat,
- wherein the light guide comprises a material having a first surface and a second surface opposite the first surface and an edge between the first and second surfaces, the light exits from the first or second surface, and the light with the integrated light and thermal guides provides for air flow proximate the first and second surfaces,
- wherein the light source is located at the edge of the light guide in order to optically couple the light into the light guide at the edge,
- wherein the light includes a light frequency shifting material.
2. The light of claim 1, wherein the light frequency shifting material comprises a dye.
3. A light with integrated light and thermal guides, comprising:
- a light source;
- a light guide coupled to the light source for receiving and distributing light from the light source, wherein the light is transported within the light guide until the light exits from a surface of the light guide; and
- a thermal guide integrated with the light guide for providing thermal conduction from the light source for cooling the light, wherein the thermal guide comprises a solid material capable of conducting heat from the light source and dissipating the heat,
- wherein the light guide comprises a material having a first surface and a second surface opposite the first surface and an edge between the first and second surfaces, the light exits from the first or second surface, and the light with the integrated light and thermal guides provides for air flow proximate the first and second surfaces,
- wherein the light source is located at the edge of the light guide in order to optically couple the light into the light guide at the edge,
- wherein the light guide comprises a sheet of material having a non-planar shape.
4. The light of claim 3, wherein the first or second surface of the light guide includes light extraction features.
5. The light of claim 4, wherein the light extraction features comprise a pattern of dots.
6. The light of claim 4, wherein the light extraction features comprise prisms.
7. The light of claim 4, wherein the light extraction features comprise lenslets.
8. The light of claim 3, further comprising a reflective layer on one side of the light guide.
9. A light with integrated light and thermal guides, comprising:
- a light source;
- a light guide comprising a material having a first surface and a second surface opposite the first surface and an edge between the first and second surfaces, wherein the second surface forms an interior volume, the light guide is coupled to the light source for receiving and distributing light from the light source through the first or second surface, and the light is transported within the light guide until the light exits from the first or second surface of the light guide, wherein the light source is located at the edge of the light guide in order to optically couple the light into the light guide at the edge; and
- a thermal guide at least partially contained within the interior volume and integrated with the light guide for providing thermal conduction from the light source for cooling the light, wherein the thermal guide comprises a solid material capable of conducting heat from the light source and dissipating the heat,
- wherein the light includes a light frequency shifting material.
10. The light of claim 9, wherein the light frequency shifting material comprises a dye.
11. A light with integrated light and thermal guides, comprising:
- a light source;
- a light guide comprising a material having a first surface and a second surface opposite the first surface and an edge between the first and second surfaces, wherein the second surface forms an interior volume, the light guide is coupled to the light source for receiving and distributing light from the light source through the first or second surface, and the light is transported within the light guide until the light exits from the first or second surface of the light guide, wherein the light source is located at the edge of the light guide in order to optically couple the light into the light guide at the edge; and
- a thermal guide at least partially contained within the interior volume and integrated with the light guide for providing thermal conduction from the light source for cooling the light, wherein the thermal guide comprises a solid material capable of conducting heat from the light source and dissipating the heat,
- wherein the light guide comprises a spherical shape.
12. The light of claim 11, wherein the first or second surface of the light guide includes light extraction features.
13. The light of claim 12, wherein the light extraction features comprise a pattern of dots.
14. The light of claim 12, wherein the light extraction features comprise prisms.
15. The light of claim 12, wherein the light extraction features comprise lenslets.
16. The light of claim 11, wherein the light guide includes a plurality of apertures.
Type: Application
Filed: Oct 11, 2013
Publication Date: Feb 13, 2014
Applicant: 3M INNOVATIVE PROPERTIES COMPANY (St. Paul, MN)
Inventors: RAYMOND P. JOHNSTON (LAKE ELMO, MN), MICHAEL A. MEIS (STILLWATER, MN), MARTIN KRISTOFFERSEN (PORSGRUNN)
Application Number: 14/051,616
International Classification: F21V 29/00 (20060101);