(12) Unlted States Patent
`(10) Patent No.:
`US 7,670,021 B2
`
`Chou
`(45) Date of Patent:
`Mar. 2, 2010
`
`USOO7670021B2
`
`(54) METHOD AND APPARATUS FOR
`THERMALLY EFFECTIVE TRIM FOR LIGHT
`FIXTURE
`
`)
`
`75
`
`(
`
`.
`Inventor. Der Jeou Chou, Mesa, AZ (US)
`.
`.
`(73) Ass1gnee. Enertron, Inc., Tempe, AZ (US)
`.
`.
`.
`.
`.
`( * ) Not1ce:
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 1 day.
`
`5,463,280 A
`5,575,459 A
`5,655,830 A
`5,688,042 A
`5,698,866 A
`5,717,320 A
`5,726,535 A
`6,149,283 A
`6,220,722 B1
`
`10/1995 Johnson
`11/1996 Anderson
`8/1997 Ruskouski
`ll/l997 Madadi et al.
`12/1997 Doiron et al.
`2/1998 Heeringa et a1.
`3/1998 Yan
`“/2000 Conway et a1.
`4/2001 B
`
`egemann
`(Continued)
`FOREIGN PATENT DOCUMENTS
`
`(22)
`
`Filed:
`
`May 20, 2008
`
`(65)
`
`-
`-
`-
`Prlor Publlcatlon Data
`US 2009/0086474 A1
`A . 2 2009
`pr
`’
`Related US. Application Data
`
`OTHER PUBLICATIONS
`
`The New York Times, “L.E.D. ’s Make for Warm Light But the Bulb
`Keeps Its C001,” Apr. 2004.
`Primary ExamineriLaura Tso
`(74) Attorney, Agent, or FirmiRobert D. Atkins
`
`(60) Provisional application No. 60/975,657, filed on Sep.
`27, 2007.
`
`(57)
`
`ABSTRACT
`
`-
`
`11 -
`(51)ItCl
`(200901)
`F21 V 29/00
`(52) US. Cl.
`....................... 362/148; 362/147; 362/404;
`362/294
`(58) Field of Classification Search ................. 362/ 147,
`362/148, 149, 150, 404, 294, 373, 547
`See application file for complete search history.
`_
`References Clted
`U.S. PATENT DOCUMENTS
`
`(56)
`
`43115955 A
`4,499,145 A
`1:33:33 2
`5,210,440 A
`5,463,229 A
`
`_
`7/1980 Ray
`2/1985 Yafiaglda et 31'
`@1332 3311321
`5/1993 Long
`10/1995 Takase et a1.
`
`A lighting assembly comprises a light fixture. The light fix-
`ture 1nc u es a trim orme
`a stam in or
`1e castin
`’ld
`‘
`f
`dby
`p'g
`d'
`‘g
`process. The trim has thermally conductive properties and
`includes a flange around a perimeter of the trim. The light
`fixture includes a light source mounted to a central portion of
`a front surface of the trim, and a heatsink formed by an
`extrusion or die casting process. The heatsink has thermally
`conductive properties and is mounted to a back surface of the
`trim. The light fixture includes an attachment mechanism
`connected to the light fixture. A recessed can housing
`mounted to a surface may be provided. The light fixture may
`be mounted to the recessed can housing by inserting the
`heatsink into the recessed can housing and engaging the
`attachment mechanism to an interior portion of the recessed
`can housing to brace the flange against the surface.
`
`19 Claims, 11 Drawing Sheets
`
`
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US 7,670,021 B2
` Page 2
`
`US. PATENT DOCUMENTS
`_
`5/2001 Katougl
`8/2002 FredericksetaL
`8/2002 Muthu etal.
`11/2002 Wu
`12/2002 Begemann
`1/2003 Chlang ~~~~~~~~~~~~~~~~~~~~~~~ 362/294
`10/2003 Rubinsztajn etal~
`4/2004 Cao
`9/2005 Chou et a1.
`
`6,234,649 Bl
`6,431,728 Bl
`6,441,558 B1
`6,481,130 Bl
`6,499,860 32
`6511209 B1*
`6,632,892 32
`6,719,446 B2
`6,942,360 B2
`
`2002/0070643 A1
`2003/0048632 A1
`2003/0071366 A1
`2003/0189829 A1
`2004/0066652 A1
`2004/0105264 A1
`2006/0239002 A1
`2008/0037255 A1*
`2008/0089071 A1*
`
`6/2002 Yeh
`3/2003 Archer
`4/2003 Rubinsztajn etal.
`10/2003 Shimizu etal.
`4/2004 Hong
`6/2004 Spero
`10/2006 Chou etal.
`2/2008 Wang ......................... 362/294
`4/2008 Wang ......................... 362/294
`
`* cited by examiner
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US 7,670,021 B2
`
`
`
`PETITIONERS, Ex. 1010
`
`

`

`US. Patent
`
`Mar. 2, 2010
`
`Sheet 2 0f 11
`
`US 7,670,021 B2
`
`FIG.2a
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US. Patent
`
`Mar. 2, 2010
`
`Sheet 3 0f 11
`
`US 7,670,021 B2
`
`
`
`
`
`
`
`
`
`
`
`
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US. Patent
`
`Mar. 2, 2010
`
`Sheet 4 0f 11
`
`US 7,670,021 B2
`
`OUTER DIAMETER
`
`INNER DIAMETER
`
`
`FIG. 4a
`
`12
`
`FIG. 4b
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`U.S. Patent
`
`Mar. 2, 2010
`
`Sheet50f11
`
`US 7,670,021 B2
`
`
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
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`

`

`US. Patent
`
`Mar. 2, 2010
`
`Sheet 6 0f 11
`
`US 7,670,021 B2
`
`FIG.6a
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US. Patent
`
`Mar. 2, 2010
`
`Sheet 7 0f 11
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`US 7,670,021 B2
`
`
`
`PETITIONERS, Ex. 1010
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`PETITIONERS, Ex. 1010
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`

`

`US. Patent
`
`Mar. 2, 2010
`
`Sheet 8 0f 11
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`US 7,670,021 B2
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`
`
`
`
`
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US. Patent
`
`Mar. 2, 2010
`
`Sheet 9 0f 11
`
`US 7,670,021 B2
`
`
`
`
`PETITIONERS, Ex. 1010
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`PETITIONERS, Ex. 1010
`
`

`

`US. Patent
`
`Mar. 2, 2010
`
`Sheet 10 0f 11
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`US 7,670,021 B2
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`
`
`PETITIONERS, Ex. 1010
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`PETITIONERS, Ex. 1010
`
`

`

`US. Patent
`
`Mar. 2, 2010
`
`Sheet 11 0f 11
`
`US 7,670,021 B2
`
`
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US 7,670,021 B2
`
`1
`METHOD AND APPARATUS FOR
`THERMALLY EFFECTIVE TRIM FOR LIGHT
`FIXTURE
`
`CLAIM TO DOMESTIC PRIORITY
`
`The present non-provisional patent application claims pri-
`ority to Provisional Application No. 60/975,657 entitled
`“Thermally Effective Trim for LED Light in Recessed Can
`Fixture Applications,” filed on Sep. 27, 2007, and claims
`priority to the foregoing application pursuant to 35 U.S.C. §
`120.
`
`FIELD OF THE INVENTION
`
`The present invention relates in general to light emitting
`devices and, specifically, to a recessed light fixture having a
`thermally effective trim.
`
`BACKGROUND OF THE INVENTION
`
`Light emitting diodes (LEDs) have been used for decades
`in applications requiring relatively low-energy indicator
`lamps, numerical readouts, and the like. In recent years, how-
`ever,
`the brightness and power of individual LEDs has
`increased substantially, resulting in the availability of 1 watt
`and 5 watt devices.
`
`While small, LEDs exhibit a high eflicacy and life expect-
`ancy as compared to traditional lighting products. A typical
`incandescent bulb has an efficacy of 10 to 12 lumens per watt,
`and lasts for about 1,000 to 2,000 hours; a general fluorescent
`bulb has an eflicacy of 40 to 80 lumens per watt, and lasts for
`10,000 to 20,000 hours; a typical halogen bulb has an eflicacy
`of 20 lumens and lasts for 2,000 to 3,000 hours. In contrast,
`red-orange LEDs can emit 55 lumens per watt with a life-
`expectancy of about 100,000 hours.
`Because LED devices generate heat, the use of LEDs or
`LED lamps in a recessed can fixture or housing can present
`problems due to the thermal constraints of LEDsiheat nega-
`tively affects the optical and electrical performance of LEDs.
`Because conventional recessed can applications tend to be
`thermally ineflicient and do not provide adequate heat venti-
`lation, an LED device installed into a recessed can housing
`will quickly generate substantial amounts of heat within the
`housing that can damage the device.
`Presently, most ofthe recessed can housings for residential
`and commercial applications are fully sealed at the can top,
`which means there is no air passage from the can to the space
`above the housing. Also, in most cases, the thermal insulation
`in the attic is placed around the can further restricting the flow
`ofheat out ofthe housing. As a result, there is no effective heat
`dissipation path from the can housing to the attic.
`An LED-based lamp installed into a recessed can housing
`requires an effective heat dissipation path to operate and to
`maintain its optical and electrical performance, longevity and
`reliability. FIG. 1 is an illustration of an LED parabolic alu-
`minized reflector (PAR) lamp with a conventional base socket
`that may be installed into a conventional recessed can hous-
`ing. Although the fins on the lamp are designed for dispersing
`the heat generated from the LED light engine, the heat is
`captured within the housing and does not dissipate. Lab
`experiments show that the fin temperature of a 15 watt LED
`lamp operated under open air conditions generates a rise in fin
`temperature of 25° C. over ambient temperature. When the
`lamp is positioned flush with the lid of a recessed can housing
`there is a 45° C. rise over ambient air temperature in the
`housing. If the lamp is further recessed into the can 2.54 cm
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`
`behind the can lid, the temperature increase is approximately
`60° C. At the ceiling of a typical home the air temperature will
`be 40° C. in the summer. As a result, the LED die junction
`temperature inside the LED lamp may be over approximately
`100° C. when the LED lamp is flush with the trim lid.
`The recessed can is one of the most widely used light
`fixtures in modern homes in the United States. There are
`
`millions of incandescent light bulbs installed into recessed
`can fixtures. Successful retrofit of an LED lamp to the exist-
`ing and new recessed can housings may result in an 80%
`decrease in lighting energy consumption and an increase of
`the lamp’s operating life from a typical 2,000 hours incan-
`descence to the 50,000 hours of an LED device.
`
`SUMMARY OF THE INVENTION
`
`In one embodiment, the present invention is a method of
`manufacturing a lighting assembly comprising providing a
`light fixture by (a) forming a trim by a stamping or die casting
`process. The trim has thermally conductive properties and
`includes a flange around a perimeter ofthe trim. Providing the
`light fixture includes (b) mounting a light source to a central
`portion of a front surface of the trim, and (c) forming a
`heatsink by an extrusion or die casting process. The heatsink
`has thermally conductive properties. Providing the light fix-
`ture includes (d) mounting the heatsink to a back surface of
`the trim opposite the light source, and (e) connecting an
`attachment mechanism to the light fixture. The method
`includes providing a recessed can housing mounted to a sur-
`face and mounting the light fixture to the recessed can hous-
`ing by (f) inserting the heatsink into the recessed can housing,
`and (g) engaging the attachment mechanism to an interior
`portion ofthe recessed can housing to brace the flange against
`the surface.
`
`In another embodiment, the present invention is a method
`of manufacturing a light fixture comprising forming a trim.
`The trim has thermally conductive properties and includes a
`flange around a perimeter of the trim. The method includes
`mounting a light source to a central portion of a front surface
`of the trim, and forming a heatsink. The heatsink has ther-
`mally conductive properties. The method includes mounting
`the heatsink to a back surface of the trim opposite the light
`source, and connecting an attachment mechanism to the light
`fixture.
`
`In another embodiment, the present invention is a method
`of manufacturing a light fixture comprising forming a trim
`including a flange around a perimeter of the trim, mounting a
`light source to a front surface ofthe trim, mounting a heatsink
`to a back surface of the trim, and connecting an attachment
`mechanism to the light fixture.
`In another embodiment, the present invention is a light
`fixture comprising a trim formed by a stamping or die casting
`process. The trim has thermally conductive properties and
`includes a flange around a perimeter of the trim. The light
`fixture includes a light source mounted to a central portion of
`a front surface of the trim, and a heatsink mounted to a back
`surface of the trim opposite the light source. The heatsink is
`formed by an extrusion or die casting process and has ther-
`mally conductive properties. The light fixture includes an
`attachment mechanism connected to the light fixture.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 illustrates a light emitting diode (LED)-based light
`source incorporating a plurality ofheatsink fins and operating
`as a parabolic aluminized reflector (PAR) light source;
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US 7,670,021 B2
`
`3
`FIG. 2a illustrates a perspective view of a recessed can
`light fixture including a thermally conductive trim and heat-
`sink for redistributing heat;
`FIG. 2b illustrates a cross-sectional view of a recessed can
`
`light fixture including a thermally conductive trim and heat-
`sink for redistributing heat;
`FIG. 3 is a perspective view illustrating the installation of
`the light fixture of FIGS. 2a-2b into a recessed can housing;
`FIGS. 4a-4b illustrate perspective views of the thermally
`conductive trim section of the light fixture of FIGS. 2a-2b
`illustrating the heatsink and light source attachment points;
`FIG. 5 is a perspective view of a thermally conductive trim
`section configured to connect to the light source shown in
`FIG. 1;
`FIGS. 611-619 illustrate perspective views of the thermally
`conductive trim of FIG. 5 coupled to the light source of FIG.
`1 having an E26/E27 electrical socket;
`FIGS. 7a-7b illustrate perspective views of the thermally
`conductive trim of FIG. 5 coupled to the light source of FIG.
`1 having a GU24 electrical socket;
`FIG. 8 is a perspective view illustrating the installation of
`the light fixture of FIGS. 611-619 into a recessed can housing;
`FIGS. 911-919 are perspective views of a thermally conduc-
`tive trim having an integrated heatsink and being configured
`to couple to a light source; and
`FIGS. 10a-10d illustrate perspective views ofmechanisms
`for coupling a light fixture to an interior portion of a recessed
`can housing.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`
`The present invention is described in one or more embodi-
`ments in the following description with reference to the Fig-
`ures, in which like numerals represent the same or similar
`elements. While the invention is described in terms ofthe best
`
`it will be
`mode for achieving the invention’s objectives,
`appreciated by those skilled in the art that it is intended to
`cover alternatives, modifications, and equivalents as may be
`included within the spirit and scope of the invention as
`defined by the appended claims and their equivalents as sup-
`ported by the following disclosure and drawings.
`FIGS. 2a and 2b illustrate recessed can fixture 10 housing
`a light source. FIG. 2a shows a perspective view of fixture 10,
`while FIG. 2b shows a cross-sectional view. Light fixture 10
`is a thermally eflicient structure that enables a heat-generat-
`ing light source such as an LED lamp to safely operate in a
`typical top sealed recessed can housing. Although recessed
`light fixtures provide various aesthetic and architectural ben-
`efits to homeowners and businesses, they generally provide
`poor ventilation and, as a result, can cause a significant
`amount ofheat build-up within the housing. In addition to the
`potential fire risk of excessive heat build-up, heat may nega-
`tively affect the performance of the light fixture itself.
`Excessive heat minimizes the lifespan ofboth conventional
`light bulbs and LED light sources. In some cases, excessive
`heat also modifies the operating properties of a light source.
`For example, because the light generation properties of many
`LED light sources are at least partially governed by tempera-
`ture, a significant change in the ambient temperature sur-
`rounding an LED light source may cause a change in the
`output color of light emitted from the device. Accordingly, a
`thermally eflicient fixture minimizes both the risk of fire and
`the effect of temperature on the output color and lifespan of
`the light source contained within the fixture.
`Fixture 10 is configured to install into both conventional
`12.7 cm (5 inch) and 15 .24 cm (6 inch) recessed can housings.
`However, fixture 10 may be configured to be installed into a
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`
`recessed can housing having other geometries. Depending
`upon the installation, different attachment mechanisms may
`be used to secure fixture 10 within the housing. As new
`recessed housings are developed with different geometries,
`new attachment mechanisms with different lengths or other
`attributes can be manufactured for coupling to and installing
`fixture 10 into those housings.
`Fixture 10 includes several components that are coupled
`together to provide eflicient dissipation of heat energy from
`within the device. Fixture 10 includes trim 12. Trim 12
`
`includes a flange that, after installation of fixture 10, pro-
`trudes from the recessed can housing. Heatsink 14 is coupled
`to trim 12 to facilitate the removal ofheat energy from trim 12
`and fixture 10. Light source 15 (shown on FIG. 2b) is directly
`mounted to a front surface of trim 12 and acts as the light
`source of the device. Fixture 10 includes an electrical socket
`
`16 for connecting the light source to an electricity source.
`Socket 16 may include an E26/E27 bulb socket or a GU24
`socket. Depending upon the application, the electricity source
`may be a standard 120 VAC, 220 VAC, 277 VAC, or other AC
`source or a DC power source. If the power source is an AC
`power source and the light source is configured to operate
`using a DC power source, an AC to DC converter circuit may
`be connected between socket 16 and the light source to con-
`vert the AC power source into a DC source. In one embodi-
`ment,
`the conversion circuit
`includes circuit board 17
`mounted within heatsink 14. In such a configuration, heatsink
`14 facilitates the removal of heat energy from both trim 12
`and circuit board 17. Window or lens 23 is connected to trim
`
`12 to form an output portal for light generated by light source
`15. Attachment clips 18 are connected to fixture 10 and allow
`fixture 10 to be mounted within a recessed can housing. In one
`embodiment, clips or torsion springs 18 are connected to trim
`12. The geometry of clips 18 is adjusted to install fixture 10
`into recessed can housings having different sizes. Mounting
`brackets (not shown) configured for a particular recessed can
`housing may be connected between clips 18 and fixture 10 to
`adjust the placement of clips 18.
`Turning to FIG. 3, fixture 10 is inserted into recessed can
`housing 21. Socket 16 is connected to an electricity source
`made available within recessed housing 21. Clips 18 are
`compressed and inserted into housing 21. After insertion,
`clips 18 expand and engage with apertures 19 fixed to the
`interior surface of the housing to secure fixture 10 within
`housing 21. After installation, heatsink 14 resides substan-
`tially within the housing and trim 12 resides substantially
`outside the housing. The outer flange of trim 12 may contact
`a structural surface that surrounds the recessed housing such
`as a ceiling or wall surface (not shown). As clips 18 expand
`and exert force against an interior surface of the recessed can
`housing (such as apertures 19), clips 18 exert force on fixture
`10 and, specifically, pull the flange portion of trim 12 against
`the surface surrounding the recessed can application.
`During operation, the light source generates heat. In a
`conventional recessed can fixture, the heat would ordinarily
`be generated by the light bulb and travel upwards within the
`housing. After leaving the light bulb, the heat is trapped in the
`recessed housing. As the device generates additional heat, the
`temperature within the housing increases and negatively
`affects the performance ofthe light fixture. In some cases, the
`excess heat shortens the operative lifetime of the device or
`degrades the optical qualities of the light source. In other
`cases, the excess heat may result in a fire risk. Typical incan-
`descent recessed can fixtures require thermal cutoffdevices to
`be connected in series with the incandescent lamp to prevent
`a fire risk when overheating.
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US 7,670,021 B2
`
`5
`In the present embodiment, however, as the light source
`operates, heat is transferred directly into trim 12 from the
`light source. As the temperature of trim 12 increases, heat is
`vented from the flange portion of trim 12 that resides outside
`the recessed can housing. Also, because trim 12 is connected
`to heatsink 14, a portion of the heat residing in trim 12 is
`transmitted into heatsink 14 where it is then vented within the
`
`recessed housing. Although some heat is vented into the
`recessed housing via heatsink 14, a majority of heat is dissi-
`pated from trim 12 outside the housing. Accordingly, fixture
`10 minimizes heat build-up within the recessed housing.
`In this configuration, heat energy flows from the light
`source, into trim 12, where a portion of the heat energy is
`dissipated from trim 12. Heat energy remaining in trim 12 is
`transferred into heatsink 14. As such, heatsink 14 may be
`regarded as acting as a heatsink for trim 12 rather than the
`light source directly.
`Trim 12 and the flange oftrim 12 generally dissipates more
`heat energy from the light source than heatsink 14. By doing
`so, trim 12 minimizes heat build-up within the recessed can
`housing. The following analysis describes an example instal-
`lation of fixture 10 and illustrates a process for determining
`the ratio of energy dispersed from trim 12 versus heatsink 14.
`In the example, trim 12 includes a thermally conductive mate-
`rial such as aluminum, and has an outer diameter of 200 m,
`an inner diameter of 130 mm and a depth of42 mm (see FIG.
`4a). Accordingly, trim 12 has an approximate surface area of
`Atrim:0.0296 m2. To determine the percentage of heat dissi-
`pated by both trim 12 and heatsink 14 the convection heat
`transfer and radiation heat transfer for each component must
`be determined.
`
`Convection heat transfer (QCOW) for trim 12 is shown by
`equation (1):
`Qmfllh Am-m H
`
`(1)
`
`where
`
`n: trim efficiency;
`h: convection heat transfer coefficient (W/O C.-m2), typical
`free convection coefiicient:5, plus approximated radiation
`effect of 5, giving a total estimated value of 10; and
`dT: temperature difference between the trim and the ambi-
`ent air (0 C.).
`In equation (1), nfian h mL/mL where mL:(h/(k*t*
`L))“2*L3/2. Accordingly, mL:(10/(180x0.002><0.064))1/2><
`0.0643/2 or 0.33. As such, nfian h 0.33/0.33:0.965.
`Radiation heat transfer for trim 12 is shown by equation
`(2)1
`
`Qrad:60AmmF(Tm-m4- T”174)
`
`(2)
`
`where
`e: emissive ~0.90;
`o: Stefan-Boltzmann constant 5.669><10'8 (W/O K.4-m2);
`and
`
`F: shape factor of ~0.95.
`The same equations can be established for heatsink 14. In
`the example, heatsink 14 includes a thermally conductive
`material and has a plurality of fins having an effective surface
`area of approximately Aheatsmk:0.065 m2.
`Convection heat transfer (QCOW) for heatsink 14 is shown
`by equation (3):
`QCoernh Aheatsink dT
`
`(3)
`
`where
`
`n: heatsink efficiencyrr] (heatsink base)><n (heatsink fins);
`h: convection heat transfer coefficient (W/O C.-m2), typical
`free convection coefficient:5;
`
`6
`dT: temperature difference from the heatsink base to the
`ambient air (0 C.); and
`nfian h mL/mL.
`In equation (3), nfian h mL/mL where mL:(2*h/(k*t*
`L))1/2*L3/2. Accordingly, mL:(2X5(20*23*2+52*J‘E)/52*J13)/
`(180><0.005><0.060))1/2><0.0603/2 or 0.52. Accordingly, «Han
`h 0.52/0.52:0.91.
`
`Radiation heat transfer for heatsink 14 is shown by equa-
`tion (4):
`4
`4
`7
`de’EOAheazsinkF (Theatsink _Taml7 )
`
`(4)
`
`where
`
`e: emissive ~0.30;
`o: Stefan-Boltzmann constant 5.669><10'8 (W/O K.4-m2);
`and
`
`F: shape factor of ~0.5.
`Having determined the convection and radiation heat trans-
`fer equations for trim 12 and heatsink 14, it is possible to
`determine the energy balance of the system. The system
`includes trim 12, heatsink 14, and the LED light source that
`generates heat energy. The energy balance is given by equa-
`tion (5):
`Qled: Qtrim+Qheatsink
`
`(5)
`
`Assuming worst case conditions, the energy generated by
`an LED light source (Qled) is approximately 15 watts. The
`ambient temperature of heatsink 14 (Theamnk) deposited
`within a fully-insulated recessed can housing is approxi-
`mately 50° C. The ambient temperature of trim 12 (Tmm)
`residing outside the recessed can housing is approximately
`35° C. The ambient temperature of the room (Tamb)
`is
`approximately 25° C. Given these conditions, it is possible to
`determine the energy stored in trim 12 and heatsink 14. The
`energy within trim 12 (Qmm) is determined by equation (6):
`Qm‘m : Qcorw+dei
`(6)
`
`equation (6), QmmrnhAmde+
`With reference to
`eoAtrimF (Ttfim4—Tamb4). Qtfim:0.965><5><0.0296><(Tm.m—
`35)+0.95><5.669><10'8x0.0296><0.9><(Tm.m4—3084). Accord-
`trim
`ingly, Qm-m:(0-143 Ttfim—4.99)+(1.43><10‘9><T
`4—12.86).
`The energy within heatsink 14 (Qheamnk) is determined by
`equation (7):
`Q}.eatsink: Qcorw+dei
`
`(7)
`
`With reference to equation (7), QheatsmkrnhAheatmk
`dT+€OAheatsink F (Theatsink4_Tamb4)’ Qheatsink:0’91X0’065><
`5X(Theatsink_50)+0’3><5‘669x10—8X0’065X0'5X(Theatsink4_
`heatsink
`3234). Accordingly, Qheatsmk:0.295 T
`—14.78+5.527><
`10—10 Theatsink4—601.
`Assuming the temperature of heatsink 14 is equal to the
`temperature of trim 12 (T:Tm.m:Theam.nk), equations (6) and
`(7) can be combined to generate equation (8):
`
`15:0.438T+1.983x10’QI4—38.64
`
`(8)
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`Numerical analysis of equation (8) results in a value of
`T:~610 C.
`
`With the energy balance for the system, it is possible to
`determine the amount of heat transfer from trim 12 and heat-
`
`60
`
`sink 14 into the ambient air surrounding fixture 10. The
`energy dissipated by trim 12 at approximately 64.10 C. is
`given by equation (9):
`erim : Qcorw+dei
`
`(9)
`
`65
`
`mm dT+eoAmm
`With reference to equation (9), Qmm:nhA
`trim
`trim
`F (T
`4—Tamb4). Qtfim:(0.l43 T
`—4.99)+(1.43><10‘9><
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US 7,670,021 B2
`
`7
`
`Tmm4—l2.86). Accordingly, Qtrim:9’78 Watts. As such, trim
`12 dissipates approximately 65% of the heat energy gener-
`ated by the LED light source.
`The energy dissipated by heatsink 14 at approximately
`64.10 C. is given by equation (10):
`erim :Qcorw+dei
`
`(10)
`
`With reference to equation (10), Qheatsmkrnh Aheamnk
`dT+€OAheatsink
`F
`(Theatsink4_Tamb4)’ Qheatsink:(0’295
`ThmtSmk—l4.78)+(5.527><10‘10
`Theatsink4—601). Accord-
`ingly, in this example, Qheamnk:5 .22 Watts.As such, heatsink
`14 dissipates approximately 35% of the heat energy gener-
`ated by the LED light source.
`As shown in the example, fixture 10 efliciently dissipates a
`majority ofheat generated by the light source through trim 12
`and outside of the recessed can housing. By doing so, fixture
`10 minimizes heat build-up within the recessed can housing
`and mitigates the deleterious effects of heat on the light
`source of fixture 10.
`
`Trim 12 includes a thermally conductive material such as
`aluminum, aluminum alloys, copper, thermally conductive
`plastics, or thermally conductive carbon fiber composite
`material. Trim 12 is formed using a one-piece stamping
`manufacturing process, however other processes such as die
`casting, deep draw stamping, and those that combine multiple
`pieces to form trim 12 may be used. Trim 12 includes an outer
`flange portion and a light source attachment point. The outer
`flange protrudes from fixture 10 and, after installation of
`fixture 10, may contact a ceiling or wall surface. Depending
`upon the application, the flange portion of trim 12 may
`include features such as grooves and beveled edges that
`increase the surface area of trim 12 and allow it to dissipate
`heat energy more efliciently. Trim 12 may also be painted
`with a thermally conductive material, or include other surface
`decorations.
`
`Trim 12 includes a light source attachment point located
`inwardly from the flange. The attachment point provides a
`mount point for physically mounting the light source to trim
`12. The attachment point may include features such as open-
`ings or recesses to facilitate the formation of an electrical
`connection between socket 16 and the light source. For
`example, the attachment point includes one or more holes
`through which electrical wiring passes, see FIGS. 4a and 4b.
`As the light source generates heat, the heat is transferred into
`trim 12 at the attachment point. From there, the heat is trans-
`ferred into both the flange of trim 12 and into heatsink 14.
`FIGS. 4a and 4b illustrate an embodiment of trim 12. In
`FIG. 4a a front surface of trim 12 is shown. Trim 12 is
`
`manufactured as a single piece of stamped aluminum and
`includes a central attachment area 20. Attachment point 20
`serves as a mount point for the light source. The light source
`is connected to attachment area 20 oftrim 12 using a plurality
`of screws or other fasteners. A thermally conductive material
`such as thermal grease or phase change thermally conductive
`pad is deposited over attachment area 20 between the light
`source and trim 12 to facilitate the eflicient conduction ofheat
`
`energy from the light source to trim 12. A plurality of holes
`20a are formed close to attachment area 20 through which
`wires can pass to electrically connect the light source to
`socket 16 and an electricity source. A seal or grommet may be
`placed within holes 2011 around the wires to prevent air flow
`through holes 20a. Trim 12 includes flange 22. After instal-
`lation of fixture 10 into a recessed can housing, flange 22
`projects from the housing and the front surface of trim 12
`faces away from an interior portion of the recessed can hous-
`ing. Accordingly, as heat energy enters trim 12 and moves to
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`flange 22, flange 22 dissipates the heat from fixture 10 outside
`the recessed can housing into a room or oflice rather than into
`the housing itself.
`Turning to FIG. 4b, a rear surface oftrim 12 is shown. Trim
`12 includes heatsink attachment point 24. Heatsink attach-
`ment point 24 includes a plurality of fixture points 24a for
`connecting heatsink 14 to trim 12 and is located approxi-
`mately opposite light source attachment area 20. A thermally
`conductive material is deposited between trim 12 and heat-
`sink 14 to facilitate the transfer of heat. Accordingly, after
`installation, the central portion oftrim 12 is disposed between
`the light source and heatsink 14.
`Referring back to FIG. 2, lens 23 is mounted over the light
`source attachment point of trim 12 and provides a portal
`through which light generated by the light source is transmit-
`ted from fixture 10. Lens 23 is attached to trim 12 using a
`friction coupling, adhesive, or a fastener such as a clip or
`screw. Lens 23 includes a substantially transparent material
`such as glass or clear plastic. In one embodiment, lens 23
`includes poly-carbonate material. Lens 23 may include one or
`more optical features that alter light passing through lens 23
`to provide a desired optical effect. For example, lens 23 may
`be translucent or frosty and may include polarizing filters,
`colored filters or additional lenses such as concave, convex,
`planar, “bubble”, and Fresnel lenses. If the light source gen-
`erates light having a plurality of distinct colors, for example,
`lens 23 may be configured to diffuse the light to provide
`sufficient color blending.
`Heatsink 14 includes a thermally conductive material such
`as those used to fabricate trim 12 and is formed using an
`extrusion, die casting or stamping process. Heatsink 14
`includes a plurality of fin structures to facilitate dissipation of
`heat energy collected within heatsink 14 into the surrounding
`air. Heatsink 14 is mechanically connected to trim 12 to
`provide for transfer of heat energy from trim 12 to heatsink
`14. In one embodiment, heatsink 14 is connected to trim 12
`with a plurality of fasteners such as screws or bolts. A ther-
`mally conductive material such as thermal grease, a thermally
`conductive pad, or a thermal epoxy is deposited between
`heatsink 14 and trim 12 to enhance the thermal connection
`
`between the two structures. The thermal grease may include a
`ceramic, carbon or metal-based thermal grease.
`Light source 15 is connected to trim 12 and acts as a light
`source for fixture 10. To facilitate transmission of thermal
`
`energy from light source 15 to the attachment area of trim 12,
`a layer ofthermally conductive material is deposited between
`light source 15 and trim 12. The thermally conductive mate-
`rial may include thermal grease, epoxy, a thermal interface
`pad, or a phase change thermally conductive material. In
`various embodiments, the light source may include conven-
`tional incandescent light bulbs, light emitting diodes (LEDs),
`light engines or other light sources. In one embodiment, the
`light source is a light engine that includes a plurality of LEDs.
`The plurality of LEDs are electrically interconnected and a
`single electrical input into the light engine is used to power
`each ofthe LEDs.Any class of LED device may be used in the
`light engine, including individual die, chip-scale packages,
`conventional packages, and surface mounted devices (SMD).
`The LED devices are manufactured using semiconductor
`materials,
`including, for example, GaAsP, GaP, AlGaAs,
`AlGaInP, GaInN, or the like. In one installation, the light
`engine includes a single printed circuit board (PCB) having a
`plurality of connected LEDs. The LEDs are electrically inter-
`connected using PCB traces or wirebonds so that when a
`supply voltage is applied to the light engine, each ofthe LEDs
`is activated and outputs light.
`
`PETITIONERS, Ex. 1010
`
`PETITIONERS, Ex. 1010
`
`

`

`US 7,670,021 B2
`
`9
`In the light engine, each of the individual LEDs have a
`particular color output correspondin