Patent Grant
10598320
In various embodiments, the present invention relates to illumination devices, in particular illumination devices incorporating light-emitting diodes (LEDs).
One of the most common light fixtures is the recessed can downlight (RCD), which is an open-bottom can that contains a lightbulb, most commonly an incandescent bulb or a fluorescent bulb. The fixture is typically connected to the power mains at 120 to 277 volts, 50/60 Hz. RCDs are generally installed during the construction of a building before the ceiling material (such as plaster or gypsum board) is applied. Therefore, they are not easily removed or substantially reconfigured during their lifetime.
RCDs generally also accommodate lightbulbs having various sizes, different overall dimensions (i.e., length, width, and diameter), and varied light-distribution capabilities. For example, various bulbs have narrow, medium, or wide (flood) light distributions. Therefore, the internal features of the RCD are constructed to accommodate many (if not all) different bulb types. Such features include mechanisms to adjust the vertical position of the bulb socket, as well as reflectors that channel and distribute the light. Because there are so many different lightbulbs and finishes, a very large number of trim rings and optics combinations may be utilized in RCDs, in addition to the various spacers that accommodate the bulbs. Thus a complex arrangement of parts is needed for each RCD that is produced.
Because LEDs have very high efficiency (e.g., 100 lumens per watt compared to 10-15 lumens per watt for incandescent or halogen lights) and a long lifetime (e.g., 10,000-100,000 hours), they are attractive for virtually all lighting applications. LED retrofit fixtures have been designed to replace existing, installed RCD fixtures. U.S. Ser. No. 14/660,159, filed on Mar. 17, 2015, for example, describes a retrofit kit that enables retrofitting of a wide variety of different RCDs (e.g., RCDs incorporating fluorescent bulbs) with a single “universal” LED-based fixture that is quickly and efficiently installable. Within the retrofit kit, the LED light sources and control electronics are modularized for ease of assembly and installation. In addition, the retrofit kit may be utilized substantially independently of the specific lightbulb being replaced yet conforms to the volume and desired level of illumination of the existing RCD.
A retrofit kit as described in the '801 application may include a discrete driver module featuring circuitry for supplying power to and controlling the LED light source(s), as well as, in various embodiments, circuitry for controlling the LEDs based on sensed temperature (for example, the temperature of the LEDs themselves or of one or more temperature sensors such as thermistors in close proximity to the LEDs). The driver module is electrically connected to a discrete lighting module featuring one or more LEDs (for example, several LEDs arranged in a rectilinear array) via a flexible conduit that contains and protects one or more wires carrying electrical signals between the two modules. The lighting module may incorporate one or more temperature sensors for sensing the temperature of the LED(s) and/or the ambient temperature, and the driver module may incorporate thermal-feedback circuitry for controlling power supply to the LED(s) based on the sensed temperature. The lighting module also typically incorporates an integral or removable heat sink.
Unfortunately, the high power levels often required to drive an LED retrofit solution to maintain previous lighting levels may generate so much heat that merely heat-sinking the LEDs can prove insufficient. LED lifetime can be substantially shortened by excessive operating temperatures; in general, it is advisable to maintain the LED below 100° C. during operation. Indeed, even where such passive measures as finned heat sinks are sufficient from a performance perspective, they may be incompatible with the physical restrictions of a retrofit; the volume within a light source such as an RCD is limited, and the airflow needed for effective heat sinking may be impossible within the fixture space. Even when there is adequate room for a large heat sink, it may displace the light source so as to create glare and ultimately impose a cap on light output. For example, it may be necessary to change the configuration to position the LEDs lower in the can, resulting in an out-of-focus condition for the LEDs and/or considerable visual glare, which is highly undesirable. Placing the heat sink outside the can (reflector) also is usually not possible due to the mounting and support structure of the light fixture. Moreover, the region above the can may be filled with insulation and the building's structural elements, such as rafters and beams, may either restrict airflow or make the use of the space impossible.
The present invention is directed toward the problem of dissipating heat from LEDs within a confined space. Embodiments of the invention address this problem simplifying active cooling or “enhanced” passive cooling.
Accordingly, in a first aspect, the invention pertains to an illumination device. In various embodiments, the illumination device comprises a lighting module comprising one or more LEDs; a driver module, physically separate from the lighting module, and comprising circuitry for supplying power to the one or more LEDs; a flexible conduit electrically connecting the driver module to the lighting module; an air pathway following the conduit; and a cooling facility for directing air through the lighting module and the driver module, such that the air passes through the air pathway. In some embodiments, the pathway is through the conduit. For example, the device may further comprise a duct coaxially surrounding the conduit, with the pathway running through the coaxial duct. Alternatively, the device may further comprise a duct adjacent to the conduit, with the pathway running through the adjacent duct.
In some embodiments, the cooling facility is powered by the driver module. The cooling facility may consist of or comprise a fan, which may be disposed in the lighting module, the driver module, between the lighting and driver modules, or outside both modules. In some embodiments, the fan is configured to draw air through one of the modules and blow air through the other module.
The device may further comprise a sensor for sensing a temperature of at least one of the LEDs, and a controller, operatively coupled to the sensor, for controlling operation of the cooling facility based at least in part on the sensed temperature.
The term “substantially” or “approximately” means±10% (e.g., by weight or by volume), and in some embodiments, ±5%. The term “consists essentially of” means excluding other materials that contribute to function, unless otherwise defined herein. Nonetheless, such other materials may be present, collectively or individually, in trace amounts. Reference throughout this specification to “one example,” “an example,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present technology. Thus, the occurrences of the phrases “in one example,” “in an example,” “one embodiment,” or “an embodiment” in various places throughout this specification are not necessarily all referring to the same example. Furthermore, the particular features, structures, routines, steps, or characteristics may be combined in any suitable manner in one or more examples of the technology. The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the claimed technology.
The foregoing will be more readily understood from the following detailed description of the invention, in particular, when taken in conjunction with the drawings, in which:
Further details of the driver and lighting modules 110, 115 are illustrated in
Alternatively, the decision making circuitry 212 and/or the cooling power supply 230 mechanism can lie within the heat sink or lighting module 115 itself. For example, a bi-metallic relay or switch in-line with the power to the cooling element 225 can respond to an excessive sensed temperature and provide power thereto.
In the embodiment 200, the cooling element 225 is located in the lighting module and a duct 237 delivers the cooling air to the LEDs 220. A second duct 240, coextensive and, in some embodiments, coaxial with the conduit 125 delivers the air flow to the driver module 110. A representative coaxial arrangement is shown in
Because active cooling usually involves forcing airflow or convection, it is convenient to provide the source of power 230 for this function within the driver module 110. However, because typical LED drivers exhibit relatively high energy efficiency (80-90% is typical), whereas the LEDs have an electrical-to-optical conversion efficiency of approximately 20%, it may be deemed preferable to locate the cooling element 225 in the driver module 110 rather than within the lighting module 115. This arrangement also avoids the need to run wires to power the cooling element 225 from driver module 110 to the lighting module 115.
As shown in
Other approaches to heat removal may also or alternatively be employed. One such approach is the use of a heat pipe containing a fluid that can be vaporized, thus transporting heat evaporatively. The heat is transferred to a cooler region where a radiator is located and released via condensation of the fluid. Heat pipes can be made very compact to fit within the envelope of a fixture. Moving the heat away from the LEDs 220 allows a fan or other cooling facility to exhaust the released heat to the environment using the power provided by the LED driver.
The controller 210 and temperature circuitry 212, or processing unit that executes the relevant commands and instructions, may be a general-purpose computer processor, but may utilize any of a wide variety of other technologies including a CSIC (customer-specific integrated circuit), ASIC (application-specific integrated circuit), a logic circuit, a digital signal processor, a programmable logic device such as an FPGA (field-programmable gate array), PLD (programmable logic device), PLA (programmable logic array), RFID processor, smart chip, or any other device or arrangement of devices that is capable of implementing the steps of the processes of the invention.
The programming necessary to achieve the functionality described above is straightforwardly implemented by those skilled in the art without undue experimentation. The controller itself may be implemented in hardware, as described above, in software or as a combination of the two. For embodiments in which functionality is provided as one or more software programs, the programs may be written in any of a number of high level languages such as FORTRAN, PASCAL, JAVA, C, C++, C #, BASIC, various scripting languages, and/or HTML. Additionally, the software can be implemented in an assembly language directed to the microprocessor resident on a target computer; for example, the software may be implemented in Intel 80x86 assembly language if it is configured to run on an IBM PC or PC clone. The software may be embodied on an article of manufacture including, but not limited to, a floppy disk, a jump drive, a hard disk, an optical disk, a magnetic tape, a PROM, an EPROM, EEPROM, field-programmable gate array, or CD-ROM. Embodiments using hardware circuitry may be implemented using, for example, one or more FPGA, CPLD or ASIC processors.
The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. In addition, having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. In particular, embodiments of the invention need not include all of the features or have all of the advantages described herein. Rather, they may possess any subset or combination of features and advantages. Accordingly, the described embodiments are to be considered in all respects as only illustrative and not restrictive.
This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/020,230, filed on Jul. 2, 2014, the entire disclosure of which is hereby incorporated herein by reference
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| Number | Date | Country | |
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| Number | Date | Country | |
|---|---|---|---|
| 62020230 | Jul 2014 | US |
