Light emitting diode (LED) lighting systems are becoming more prevalent as replacements for existing lighting systems. LEDs are an example of solid state lighting and have advantages over traditional lighting solutions such as incandescent and fluorescent lighting because they use less energy, are more durable, operate longer, can be combined in red-blue-green arrays that can be controlled to deliver virtually any color light, and contain no lead or mercury.
In many applications, one or more LED dies (or chips) are mounted within an LED package or on an LED module, which may make up part of a lighting unit, lamp, “light bulb” or more simply a “bulb,” which includes one or more power supplies to power the LEDs. An LED bulb may be made with a form factor that allows it to replace a standard threaded incandescent bulb, or any of various types of fluorescent lamps.
Since, ideally, an LED bulb designed as a replacement for a traditional light source needs to be self-contained, the power supply and the LED package or packages are often near each other. Although LED bulbs typically include a heat sink, the heat generated by the LEDs can raise the temperature of the power supply components, and the resulting temperature increase must be taken into account in the power supply design.
Embodiments of the present invention provide for thermal isolation between the power supply and the LED assembly of an LED lamp, in most cases allowing the power supply for the lamp to operate in a lower temperature range than would otherwise be possible. In some embodiments, a thermal isolation device is used to maintain a thermal transfer gap or thermal transfer gaps between the power supply and the LED assembly, reducing the amount of direct thermal interaction between the two. Thus, a separate heat dissipation solution can be implemented for the LED assembly and the power supply, providing for greater design flexibility with respect to the lamp.
In some embodiments, an LED lamp includes at least one LED assembly and a power supply electrically connected to the LED assembly. At least one contact feature is provided between the power supply and the LED assembly to maintain a thermal transfer gap between the power supply and the LED assembly. In some embodiments the LED lamp includes an Edison base connected to the power supply. In some embodiments, the LED lamp includes an optical element disposed to emit light from the LED lamp. In some embodiments, a second optical element can be used, and the second optical element can be treated with phosphor.
In some embodiments, the thermal transfer gap is maintained by a thermal isolation device installed between the LED assembly and the power supply. In some embodiments, the thermal isolation device includes first and second faces, wherein each face is disposed to be proximate to either the power supply or the LED assembly for the lamp. The contact feature or a plurality of contact features are formed on or connected to one or both of the first and second faces of the thermal isolation device. In some embodiments, the contact feature comprises a triangular ridge. In some embodiments, the contact feature comprises a conical protrusion.
In some embodiments a thermal isolation device can include an attachment mechanism or attachment mechanisms to fix the thermal isolation device to the power supply portion or the LED assembly portion of the lamp, or to both. For example, the attachment mechanism can be protruding tabs, slots for receiving protruding tabs, or a combination of the two. Note that the thermal isolation device being “fixed” to a particular portion of the lamp does not necessarily mean it is directly attached to any particular component such as the power supply or an LED assembly. For example, the thermal isolation device could attach to a heat sink which is part of, or simply connected to the LED assembly portion of the lamp. The connection between the thermal isolation device and any particular portion of the LED lamp may be indirect.
An LED lamp according to example embodiments of the invention can be produced by assembling a power supply portion of the LED lamp and an LED assembly portion of the LED lamp. The thermal isolation device including at least one contact feature disposed to maintain the thermal transfer gap is also formed. The power supply portion, the thermal isolation device and the LED assembly portion of the LED lamp are then interconnected so that at least one thermal transfer gap is maintained between the power supply portion and the LED assembly portion of the LED lamp. In at least some embodiments an optical element is installed on the lamp. In some embodiments, an Edison base is provided for the power supply. In accordance with other embodiments of the present invention, the various portions of the lamp, such as the LED assembly, the power supply, a thermal isolation device and others can take the form of connectable or fastenable modules that can be interconnected to form a modular LED lamp.
The following detailed description refers to the accompanying drawings, which illustrate specific embodiments of the invention. Other embodiments having different structures and operation do not depart from the scope of the present invention.
Embodiments of the invention are described with reference to drawings included herewith. Like reference numbers refer to like structures throughout. It should be noted that the drawings are schematic in nature. Not all parts are always shown to scale. The drawings illustrate but a few specific embodiments of the invention.
The particular power supply portion of an LED lamp shown in
Still referring to
It cannot be overemphasized that the thermal insulation device of
With a thermal isolation device as illustrated in
Continuing with
Still referring to
Embodiments of the thermal isolation device can use varied fastening methods and mechanisms. For example, in some embodiments a part or a peg with a groove or ridge can snap into a corresponding hole. In some embodiments, combinations of fasteners such as tabs, latches or other suitable fastening arrangements and combinations of fasteners can be used which would not require adhesives or screws. In other embodiments, adhesives, screws, or other fasteners may be used.
Still referring to
It should be noted that the particular shape of the contact features used to create a thermal isolation gap can be chosen to minimize direct mechanical contact between the components. In the present example, the contact features substantially come to a narrow, almost pointed ridge. In another example, conical contact features substantially come to a point. This same principle applies whether or not a separate thermal isolation device is used, as similar contact features could be placed directly on the other lamp components or assemblies to maintain thermal isolation between the LED assembly and the power supply portion of a lamp without the use of a separate thermal isolation device.
The various portions of the LED lamp according to example embodiments of the invention can be made of any of various materials. The heat sink can be made of metal or plastic, as can the various portions of the housings for the components of the lamp. Plastic with enhanced thermal conductivity can be used to form the heat sink. The thermal isolation device can be made of various materials including those that resist thermal transfer such as thermally insulating plastics and polymers. The optical element can be made of glass or plastic or any other suitable optical material.
In the example embodiments shown in the figures herein, air naturally fills the thermal isolation gap and provides adequate thermal isolation. Additional thermal isolation can be obtained with various treatments of the gap. For example, gaskets could be provided to seal the gap and it could be evacuated, providing additional isolation. A sealed gap could also be filled with a gas that provides better thermal isolation properties than air. Also, the gap would be filled with thermally insulating material by way of a resin or potting compound that does not conduct heat well. Films or sheets of thermally insulating material could also be placed in the thermal transfer gap. Examples of such material include Formex™ manufactured by Formex Manufacturing, Inc. and Nomex™ manufactured by E.I. du Pont de Nemours Company.
Since LED chips typically emit light of a single color or wavelength, it is often desirable to mix multiple LED chips, each emitting a different color of light within a device or within a lamp such as lamp 600 of
It should be noted that as an alternative to producing white light by using LED chips that emit different colors and color mixing treatment, an LED lamp according to embodiments of the invention can be designed to use phosphor to emit substantially white light. With such a lamp, single-color LED devices would be used, for example, blue, violet, or ultraviolet emitting LED chips. The lamp's optical element, 602 of
Referring again to
As has been noted above, optical elements can be used in various configurations with illustrative embodiments of the lamp described herein. Also, as previously noted, various types of heat sinks and thermal isolation devices could be used with the lamp. These characteristics of embodiments of the present invention underscore the modular nature of an LED lamp and the thermal isolation device as described herein. In some embodiments, each of the thermal isolation device, the power supply portion, the optical element(s), and LED assembly portion of the lamp work as independent modules or subassemblies that can be put together into a finished lamp. In some such modular designs, some portions of the modular LED lamp can be broken down further into additional independent modules. For example, the LED assembly portion can be broken down into a heat sink and an LED assembly. In some embodiments, the heat sink may not be part of the LED assembly module, but may rather be an independent module for the modular lamp.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. Additionally, comparative, quantitative terms such as “less” and “greater”, are intended to encompass the concept of equality, thus, “less” can mean not only “less” in the strictest mathematical sense, but also, “less than or equal to.”
It should also be pointed out that references may be made throughout this disclosure to figures and descriptions using terms such as “top”, “side”, “within”, “beside”, “on”, and other terms which imply a relative position of a structure, portion or view. These terms are used merely for convenience and refer only to the relative position of features as shown from the perspective of the reader. An element that is placed or disposed atop another element in the context of this disclosure can be functionally in the same place in an actual product but be beside or below the other element relative to an observer due to the orientation of a device or equipment. Any discussions which use these terms are meant to encompass various possibilities for orientation and placement.
Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art appreciate that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown and that the invention has other applications in other environments. This application is intended to cover any adaptations or variations of the present invention. The following claims are in no way intended to limit the scope of the invention to the specific embodiments described herein.
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