USOO7883243B2
`
`(12) United States Patent
`(10) Patent N0.:
`US 7,883,243 B2
`
`Snyder
`(45) Date of Patent:
`Feb. 8, 2011
`
`(54) LED FLASHLIGHT AND HEAT SINK
`ARRANGEMENT
`
`5,463,541 A
`5,486,432 A
`
`*
`
`10/1995 Greene
`1/1996 Sh3rr3h et 31.
`
`(75)
`
`Inventor: Mark W. Snyder, Hockessin, DE (US)
`
`(73) Assignee: Streamlight, Inc., Eagleville, PA (US)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(1)) by 565 days.
`
`(21) Appl. No.: 11/779,038
`
`(22) Filed:
`
`Jul. 17, 2007
`
`5,567,036 A
`5,678,921 A
`5,785,418 A
`5,806,965 A *
`5 821 695 A
`’
`’
`5,871,272 A
`6,585,391 B1*
`6,633,152 B2
`
`............ 362/485
`
`10/1996 Theob31d et 31.
`10/1997 Kish et 31.
`7/1998 Hochstein
`9/1998 Deese ................... 362/249.04
`10/1998 Vilanilam et 31
`
`‘
`2/1999 Sharr3h et 31.
`7/2003 Koch et 31.
`.................. 362/205
`10/2003 Sh3rr3h et 31.
`
`(65)
`
`Prior Publication Data
`US 2008/0018256 A]
`Jan. 24, 2008
`
`(Continued)
`OTHER PUBLICATIONS
`
`Related U-S- Application Data
`(60) Provisional application No. 60/832106, filed 011 Jul.
`20,2006.
`
`Streamlight,1nc., “Introducing theNew Survivor from Streamlight”,
`1“th[WWW‘suemfllght‘comsumvmimfo‘hun’ primed Jufl‘ 22’
`2006*‘P8ge
`
`(5n IntCL
`(2006.01)
`FZIL 4/00
`(2006-01)
`F21V29/00
`(52) U.S. C1.
`....................... 362/294; 362/196; 362/200;
`362/373
`(58) Field of Classification Search ................. 362/294,
`362/373, 545, 547, 2027208, 646, 631, 249.02
`362/218, 345, 196, 200
`See application file for complete 56311311 history-
`References Cited
`
`(56)
`
`U.S. PATENT DOCUMENTS
`4,313,272 A
`2/1982 M3tthews
`4,531,178 A
`7,1935 Uke
`4,683,523 A
`7/1987 Olsson et 31.
`4,729,076 A
`3/1988 M3sami et 31.
`4,885,668 A
`12/1989 M3glic3 et 31.
`5,309,337 A
`5/1994 Grobeu
`5,404,281 A
`4/1995 Parker
`5,432,689 A
`7/ 1995 Sharrah et 31.
`
`“bumman
`Primary ExamineriTliomas M Sember
`(74) Attorney, Agent, or Firm—Clement A. Berard, Esq.;
`Dami, Dorfiiian, Herrell & Skillman, P.C.
`
`(57)
`
`ABSTRACT
`
`An LED light may comprise a light emitting diode selectively
`energizable for producing light;. an electronic circuit
`.for
`selectively energizmg the light emitting diode; and a heat Sink
`ofa thermally conductive material, wherein the light emitting
`diode is thermally bonded to the heat sinlc; and wherein the
`electromc circuit is attached to the heat Sink. The light may
`have a pair ofcontact springs extending from the heat sink and
`the electronic circuit may include thermal conductivity
`enhancing features
`
`68 Claims, 5 Drawing Sheets
`
`
`
`ParheHon,lnc.
`EXHIBIT
`
`1008
`
`00003 3 6
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`

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`US 7,883,243 B2
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`
`U,S, PATENT DOCUMENTS
`
`11/2004 Cassaflyetal.
`6,819,505 Bl
`6,827,468 Bl W200“ Galli
`6,942,365 Bl
`9/2005 Galli
`6,966,677 32
`“/2005 Gal“
`6,974,234 Bl
`1W2005 Galli
`7,008,084 32
`3/2006 Gal“
`7,014,335 Bl
`3/2006 Probstet a1.
`7,055,989 Bl
`6/2006 Galli
`7,083,305 B2
`8/2006 Galli
`7,220,013 B2
`5/2007 Sharrah et al.
`2004/0054386 A1
`3/2004 Martin et al.
`2005/0017366 A1
`l/2005 Galli
`2005/0024864 A1
`W2005 Galli
`2005/0057187 A1
`3/2005 011313110
`2005/0083686 A1
`4/2005 Yatsuda 9t 31-
`2005/0122713 A1
`6/2005 Hutchins
`2005/0128741 A1
`6/2005 Matthews et 31-
`2005/0161684 A1
`7/2005 Galli
`2005/0161692 A1
`7/2005 Galli
`
`2005/0168985 A1*
`2005/0201100 A1
`2005/0243558 A1
`2006/0013000 A1
`2006/0039139 A1
`2006/0067077 A1
`2006/0109655 A1
`2006/0109661 A1*
`2006/0145180 A1
`2007/0253194 A1
`
`8/2005 Chen .......................... 36Z24l
`9/2005 Cassarlyetal.
`11/2005 Van Duyn
`1/2006 Coushajneet a1.
`2/2006 Maglicaet a1.
`3/2006 Kumthampinij et a1.
`5/2006 Marlin
`5/2006 Coushajneet a1.
`7/2006 Galli
`11/2007 Sharrah et a1.
`
`.......... 362/373
`
`OTHER PUBLICATIONS
`
`Streamlight,Inc.,“SurvivorSpecifications”,http://www.streamlight.
`com/survivorispecifications.htm printed Jun. 22, 2006,2pages.
`Streamlight,
`Inc., “Survivor Parts & Accessories”, http://www.
`streamlight.com/survivorlight.c0m/surviv0riaccessoriesi200l.
`ht)“ printed Jun. 22, 2006, 1 page.
`Streamlight, Inc., “Syclone AssemblyC130000A”, 1999, 1 page.
`
`* cited by examiner
`
`00003 3 7
`
`

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`US. Patent
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`Feb. 3, 2011
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`Sheet 1 015
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`US 7,883,243 B2
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`Fig. 1
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`00003 3 8
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`U.S. Patent
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`Feb. 8, 2011
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`Sheet 3 0f 5
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`US 7,883,243 BZ
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`0000340
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`U. S. Patent
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`Feb. 8,2011
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`Sheet 4 0f5
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`US 7,883,243 BZ
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`US. Patent
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`Feb. 8
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`2011
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`Sheet 5 0f 5
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`US 7,883,243 B2
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`I__________________________________________
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`NFN.
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`US 7,883,243 B2
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`1
`LED FLASHLIGHT AND HEAT SINK
`ARRANGEMENT
`
`This Application claims the benefit of US. Provisional
`PatentApplication No. 60/832,106 filed Jul. 20, 2006, each of
`which is hereby incorporated herein by reference in its
`entirety.
`The present invention relates to a light and, in particular, to
`a light having a light emitting diode and a heat sink.
`Increasingly,
`flashlights and other portable lights are
`employing a solid state light source, such as a light-emitting
`diode (LED), particularly as the brightness of the available
`LEDs has improved and as LEDs havebecome available that
`produce bright “white” light.
`Unlike incandescent lamps which depend upon the heating
`ofa light producing filament to a high temperature to produce
`light, LEDs are desirably operated at lower temperatures at
`whichtheir efficiency and reliability is better. Thus, whereas
`it was relatively 1mimportant in many instances to remove the
`heat generated by an incandescent lamp,
`it may be quite
`important that heat generated by a high-power LED be
`removed.
`
`While incandescent lamps may be satisfactorily operated
`by applying a voltage, e.g., a battery voltage, directly to the
`lamp, such is not a desirable way in which to operate a solid
`state light source such as an LED. Thus, along with the use of
`LEDs as light sources in portable lights has come the utiliza-
`tion of electronic circuits for conditioning the electrical
`power provided by an electrical power source into a form
`more suitable for the LED, for example, for controlling the
`level of current flowing through the LED.
`As such power regulating circuit technology has been
`developed, power regulating circuits have also come to be
`employed with incandescent light sources as well as with
`solid state light sources.As a result, portable lights have come
`to include electronic circuitry as well as the usual battery (or
`batteries) and light sources.
`Because heat can be detrimental to electronic circuitry,
`there is a need to remove heat from such circuitry. In addition,
`certain failure and/or fault conditions may cause additional
`heat to be produced that could raise the temperature of elec-
`tronic circuitry to a temperature that is not only detrimental to
`the circuitry, but that could also be a hazard or a danger to the
`circuitry or otherwise.
`Accordingly, there is a need for light including a heat sink
`arrangement for removing heat from a light source and/or
`electronic circuitry of the light.
`To this end, a light may comprise a light emitting diode
`selectively energizable for producing light; an electronic cir-
`cuit for selectively energizing the light emitting diode; and a
`heat sink ofa thermally conductive material, wherein the light
`emitting diode is thermally bonded to the heat sink; and
`wherein the electronic circuit is attached to the heat sink.
`
`According to another aspect, a light may comprise a heat
`sink including a first generally rectangular planar member,
`two opposing elongated members each integrally joined to
`the first rectangular planar member, and a second generally
`rectangular member integrally joined to the two elongated
`members and to the first generally rectangular member. A
`light emitting diode may be attached to the first generally
`rectangular planar member between the two elongated mem-
`bers and circuitry for energizing the light emitting diode may
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`be attached to the second generally rectangular planar mem-
`ber between the two opposing elongated members.
`
`BRIEF DESCRIPTION OF THE DRAWING
`
`The detailed description of the preferred embodiment(s)
`will be more easily and better understood when read in c011-
`jlmction with the FIGURES of the Drawing which include:
`FIG. 1 is a view of an example embodiment of a light
`including the present arrangement;
`FIG. 2 is an isometric view of a first side of an example
`embodiment of a light according to the present arrangement;
`FIG. 3 is an isometric view ofa second side ofthe example
`embodiment of a light according to FIGS. 1 and 2;
`FIG. 4 is an exploded isometric view of the heat sink and
`LED assembly ofthe example embodiment of a light accord-
`ing to FIGS. 1-3;
`FIGS. 4A and 4B are plan views of altemative example
`embodiments ofa circuit board of an example LED assembly
`as shown in FIGS. 2 and 4; and
`FIG. 5 is a schematic diagram of an example electronic
`circuit usefiil with the light of FIGS. 1-4.
`In the Drawing, where an element or feature is shown in
`more than one drawing figure, the same alphanumeric desig-
`nation may be used to designate such element or feature in
`each figure, and where a closely related or modified element
`is shown in a figure, the same alphanumerical designation
`primed or designated “a” or “b” or the like may be used to
`designate the modified element or feature. It is noted that,
`according to common practice, the various features of the
`drawing are not to scale, and the dimensions of the various
`features are arbitrarily expanded or reduced for clarity, and
`any value stated in any Figure is given by way of example
`only.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT(S)
`
`FIG. 1 is a view of an example embodiment of a light 10
`including the present arrangement. Light 10 includes a hous-
`ing 20 including a portion 30 in which a battery or batteries
`may be provided and a portion 40 in which are a reflector 42
`and light 10' and a source ofelectrical power such as a battery
`40. Housing portion 40 may be angled with respect to housing
`portion 30, e.g., approximately perpendicularly as illustrated,
`or at another angle, or housing portions 30, 40 may be axially
`aligned, as may be desired. In the illustrated arrangement,
`light 10 may desirably be placed with base 32 on a generally
`horizontal surface or into a charger unit and remain standing
`thereon with light produced by light 10' emanating outwardly
`in a generally horizontal direction.
`A light 10' (not visible, described below) may be disposed
`at the base ofreflector 42 intemal to housing 20 substantially
`at the intersection ofthe rear oflight housing 40 and the upper
`end of battery housing 30, thereby to project a beam of light
`from reflector 40 through lens 44. Within housing 20 of light
`10 is a heat sink 100 (not visible, described below) which
`generally conforms to the geometry and shape of housing 20
`and which dissipates heat generated by light 10' therein and
`which supports the light source and electronic control cir-
`cuitry therefor.
`Battery housing portion 30 may include at its base 32 an
`access cover 36 that has hinges and/or Clasps 34 for attaching
`cover 36 to battery housing portion 30 and through which the
`battery or battery may be inserted and removed, and may
`optionally include contacts for making electrical connection
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`US 7,883,243 B2
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`with a charger unit into which light 10 may be placed for
`charging the battery in housing portion 30.
`Light source housing portion 40 may include a ring mem-
`ber that removably attaches to housing portion 40, e.g., in a
`threaded engagement therewith, for retaining reflector 42 and
`lens 44 in housing portion 40. Ring member 46 could be
`rotatable for manipulating a mechanism for adjusting the
`shape and/or focus of the beam of light produced by light 10
`and projected outwardly through lens 34.
`Housing 20 may also include a clip 50, e.g., secured at the
`rear ofhousing 20 by screws 54 engaginghousing 20 and heat
`sink 100 therein, as described below. Optionally, clip 50 may
`be pivoted, e.g., on pivot pin 58, and end 56 ofclip 50 may be
`biased against housing 20 by a spring 52 and so the end 56 of
`clip 50 may be moved toward and away from housing 20,
`thereby to facilitate clipping light 10 to a pocket, belt or other
`item, as may be convenient and/or desirable. Clip 50 may
`have an optional projection extending from end 56 towards
`housing 20 (as illustrated) or not.
`Typically, battery housing portion 30 may have a race-track
`or oval shaped cross-section, e.g. for receiving four size AA
`battery cells in a side-by-side arrangement, and light source
`housing portion 40 may be circular in cross-section. The four
`AA size battery cells may be alkaline cells, rechargeable
`NiCd cells, or another suitable battery cell(s), and may be
`utilized as cells or may be disposed in a common package to
`be a battery pack.
`Although terms such as front, back, top, bottom, and side
`may be employed in describing the example embodiment as
`illustrated by the FIGURES, the present arrangement may be
`utilized in any orientation, and so what is termed top or
`bottom herein may or may not be the top or bottom in utili-
`zation, what is termed front or back may or may not be the
`front or back in utilization, and so forth.
`FIG. 2 is an isometric view of a first side (or front side) of
`an example embodiment of a light 10' and FIG. 3 is an iso-
`metric view of a second side (or rear side) of the example
`embodiment of light 10' according to the present arrange-
`ment. Light 10' may comprise a heat sink 100, a light emitting
`diode (LED) assembly 200 attached thereto, and electronic
`circuitboards 300, 400 attached thereto .A source ofelectrical
`power, such as a battery, may be connected to circuit board
`400 and light 10' may be, and typically is, disposed in a case
`or housing.
`When light 10, 10' is operated under normal operating
`conditions, certain electronic components thereof, e.g., the
`light source (e.g., LEDassembly200) and a control device for
`the light source (e.g., component 330 on circuit board 300),
`typically generate heat that must be dissipated to prevent the
`temperature of such components fromincreasing excessively,
`e.g., to where such component could be damaged or fail, or to
`where a dangerously high temperature occurs. In normal
`operation, the light source is typically the predominant gen-
`erator of heat.
`In addition, under fault conditions such as the failure of an
`electronic component or a short circuit, the light source (e.g.,
`LED assembly 200) and components controlling the light
`source (e.g., component 330 on circuit board 300) may gen-
`erate more heat than under normal conditions. Under fault
`conditions, the control device often typically generates sub-
`stantially greater heat than other components and than it does
`under normal operation.
`Thus heat sink 100 serves the dual functions of dissipating
`heat from the light source 200 under normal operation and of
`dissipating heat from other components under fault condi-
`tions. Desirably, heat sink 1 00 dissipates sufficient heat under
`both normal and fault conditions such that no component will
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`reach or exceed a temperature which is considered by Under-
`writers’ Laboratory (UL) to be dangerously hot, thereby to be
`eligible for UL approval of light 10, 10' as a Class I, Division
`I, device. For UL approval for use in an environment subject
`to T4 gases, the maximum allowable component temperature
`for UL approval is 200° C. when the light is in a 40° C.
`ambient temperature environment. In addition, heat sink 100
`also serves the functions of supporting LED 210, ofpo sition-
`ing LED 210 to be aligned with reflector 30 of light 10, and of
`supporting electronic circuit board 300 that controls the
`operation of LED 210.
`Heat sink 100 includes a first generally rectangular mem-
`ber 110 that is generally planar and that has front and back
`broad surfaces. Heat sink 100 may include two elongated
`members 130 that are integrallyj oined to oppo sing edges,
`e.g., side edges, of first generally rectangular member 110,
`and each opposing elongated member 130 typically has
`opposing ends 132, 134 that extend beyond the top and bot-
`tom edges of first generally rectangular member 110.
`A second generally rectangular member 120 is integrally
`joined to one edge, e.g., the top edge, of first generally rect-
`angular member 110, and between the two elongated mem-
`bers 130 to which its opposing ends are integrallyj oined.
`Typically, because ends 132, 134 of elongated members 130
`in the example embodiment extend beyond the top and bot-
`tom edges of first generally rectangular member 110 and
`beyond second generally rectangular member 120, and so
`heat sink 100 may be described as having an “H”-like shape.
`LED assembly 200 is attached to one of the broad surfaces,
`e.g., the front surface, of first generally rectangular member
`110, and is typically bonded to a central region of the front
`surface thereof by a suitable thermally conductive adhesive.
`As a result LED 210 ofLED assembly is thermally coupled to
`heat sink 100 for facilitating the removal of heat produced by
`LED 210 when it is energized to produce light. LED assembly
`200 includes light emitting diode (LED) 210 that may
`attached for convenience in assembly to an electronic circuit
`board (described below) for making electrical connections
`between LED 210 and electronic circuit board300, such as by
`conductors 340, e.g., insulated wires 340. Conductors 340
`may be electrically connected to circuit board 300 by solder-
`ing, by electrically conductive adhesive, by mechanical
`crimping or swaging, or by another suitable connection.
`Electronic circuit board 300 typically carries electronic
`circuitry for controlling the energization of LED 210, and
`may comprise an electronic circuit board substrate 310 on
`which are provided various conductors and electronic com-
`ponents in conventional fashion, e.g., on either or both of the
`broad surfaces thereof. Examples of such electronic compo-
`nents carried on substrate 310 may include, e.g., an electrical
`switch 320 directly or indirectly energizing and de-energiz-
`ing LED 210, an electronic control device 330 for applying,
`removing and/or regulating or otherwise controlling electri-
`cal power applied to LED 210, and optionally various inte-
`grated circuits, transistors, diodes, resistors, capacitors, and
`the like.
`Electronic circuit board 300 may be attached to heat sink
`100 in various ways, however, a preferred attachment
`includes circuit board 300 being adjacent to second generally
`rectangular member 120, e.g., for facilitating removal ofheat
`from the electronic components thereon. While such heat
`may be produced in normal operation of light 10', additional
`heat may be produced under a fault condition, e.g., damage to
`or failure of an electronic component on circuit board 300 or
`of LED 210 or of an electrical short circuit.
`In one such mounting arrangement for circuit board 300, a
`groove 136 is provided in one elongated member 130 adja-
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`cent second generally rectangular member 120 for supporting
`a first end of circuit board 300 and a fastener 305, such as a
`screw or bolt, supports another end of circuit board 300. In
`particular, it is preferred that electronic components, such as
`a control device 330, that may generate substantial heat under
`nomlal operation and/or lmder a fault condition be disposed
`on circuit board substrate 310 in a location that is proximate
`to fastener 305, thereby to be thermally coupled to second
`generally rectangular member 120 by a relatively short ther-
`mal conduction path.
`Control device 330 may be, e.g., a transistor that controls
`application of electrical power to LED 210, such as a MOS-
`FET transistor, that operates as a power switching device, as
`a power controlling device, as a power regulating device, or
`for otherwise controlling electrical voltage or cru'rent. Circuit
`substrate 310 may include substantial electrical conductor
`area, a thicker electrical conductor, conductive vias, or
`another arrangement, proximate to the location thereon
`where fastener 305 attaches circuit board 3 00 to heat sink 100
`for reducing the thermal resistance between one or more heat
`generating components, e.g., control device 330, and heat
`sink 100. While a thermally conductive grease or adhesive
`may be employed between circuit board 300 to heat sink 100,
`it has been formd that fastener 305 alone typically is sufficient
`and that such themlal grease or adhesive is not needed in the
`example arrangement.
`Heat sink 100 in the example embodiment preferably is
`sufficient to dissipate and/or distribute heat generated by light
`10' under nomlal operation and fault conditions without hav-
`ing an exposed surface or being attached to a highly themlally
`conductive case or housing. Examples of fault conditions
`might include a short circuit of LED 210 or a short circuit
`directly applying full battery voltage to LED 210. Under
`nomlal operation and fault conditions, heat sink 100 main-
`tains LED 200, 210 and all electronic components including
`certain power handling components on circuit board 300 to a
`safe temperature, e.g., to a temperature less than 200° C.,
`whereby light 10, 10' is eligible for Underwriters’ Laboratory
`(UL) certification as a Division I, Class I, device and/or in a
`T4 gas environment.
`Electronic circuit board 400 includes circuit board sub-
`strate 410 that carries electrical conductors and various elec-
`tronic and other components in conventional fashion. Elec-
`trical contacts 420, which may be coiled spring-like
`structures of electrically conductive wire, extend from circuit
`board substrate 310 in a direction away from heat sink 100 for
`making electrical contact with the temlinals of a battery or
`other source of electrical power for light 10' and that may be
`carried either externally to light 10' or in a case or housing
`thereof. Electrical power from such power source may be
`carried by conductors 430,e.g., insulatedwires430, connect-
`ing between electronic circuit board 400 and electronic cir-
`cuit board 3 00. Conductors 430 may be electrically connected
`to circuit boards 300 and 400 by soldering, by electrically
`conductive adhesive, by mechanical crimping or swaging, or
`by another suitable connection.
`Electronic circuit board 400 is preferably attached to heat
`sink 100. For example, heat sink 100 may have a pair of
`opposing grooves or slots 130 in opposing elongated mem-
`bers 130 into which circuit board 400 is inserted. Because
`circuit board 400 in the example embodiment does not carry
`electronic components that would produce significant heat
`under either normal operation or fault conditions, it is not
`necessary to provide good themlal coupling between circuit
`board 400 and heat sink 100. Should such components be
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`carried by circuit board 400, then circuit board 400 could be
`attached to heat sink 100 is similar manner to that employed
`for circuit board 300.
`Heat sink 100 may have one or more features for increasing
`its thermal conduction capability. For example, a raised cir-
`cular area 112 on the front surface of first generally rectan-
`gular member 110 may be provided to increase the thickness
`of member 110 proximate to where LED assembly 200 is
`attached thereto, thereby to reduce the themlal resistance and
`increase the thermal mass ofmember 110. In addition, raised
`ridges may be provided extending from the raised circular
`area to further reduce themlal resistance and increase themlal
`mass. Two raised substantially semi-circular features 114 on
`the rear surface of heat sink 100 have a similar benefit.
`Substantially semi-circular features 114 also provide sur-
`faces that can contact the interior surface ofhousing 20 when
`screws 54 are tightened, and define a groove or slot 115 which
`allows any gas that might be generated by the battery or
`batteries in housing portion 30 to flow upward to a venting
`valve (not visible) typically located near or at the top of light
`10 proximate light portion 40.
`Heat sink 100 is typically and preferably disposed in a case
`or housing in use, and may be provided with a means for
`attaching heat sink 100 to such case or housing. For example,
`one or more holes 102 may be provided on the rear surface of
`heat sink 100 to receive fasteners inserted through corre-
`sponding holes in the case or housing. Holes 102 may be
`tapped or have threaded inserts to receive screws or bolts, or
`may receive self-tapping or other fasteners. The fasteners that
`engage holes 102 may also be utilized to attach a part or parts
`to the outside of the case or housing, e.g., to attach a pocket
`clip, a belt clip, a spring-loaded clip, a lanyard ring, and/or
`other part.
`Heat dissipation by heat sink 100 includes conducting heat
`from the relatively small areas whereat heat is generated, e.g.,
`at LED 210 and/or at control device 330 on circuit board 300,
`to the various members of heat sink 100, thereby to reduce
`temperature by spreading the heat over a substantially larger
`area and/or by allowing heat to be dissipated over that sub-
`stantially larger area.
`For example, heat generated by LED 210 on first generally
`rectangular member 110 is conducted due to the relatively
`high themlal conductivity of heat sink 100 from first gener-
`ally rectangular member 110 to second generally rectangular
`member 120 and to both elongated members 130 which
`would tend to be cooler because there is no heat generating
`element thereon. Similarly, heat generated by control device
`330 on electronic circuit board 300 is conducted through
`circuit board substrate 310 and fastener 305 to second gener-
`ally rectangular member 120 is conducted due to the rela-
`tively high themlal conductivity ofheat sink 100 from second
`generally rectangular member 120 to first generally rectan-
`gular member 1 10 and to both elongated members 130 which
`would tend to be cooler because there is no heat generating
`element thereon.
`If and when both LED 210 and control device 330 were to
`be generating substantial heat at the same time, the heat
`therefrom is conducted to first and second generally rectan-
`gular members 110, 120 and from first and second generally
`rectangular members 110, 120 to both elongated members
`130 which would tend to be cooler because there is no heat
`generating element thereon.
`In addition to heat conduction through heat sink 1 00 due to
`the relatively high themlal conductivity thereof, heat is also
`removed to a lesser extent by convection and by radiation,
`e.g., from the elements that are generating substantial heat as
`well as from the surface ofheat sink 100. Further, removal of
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`0000345
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`US 7,883,243 B2
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`7
`heat from heat sink 100 is thought to be aided by the exterior
`of heat sink 100, e.g., by the curved outer surfaces of elon-
`gated members 130, being shaped to generally conform geo-
`metrically to the interior surface of housing 20 in which heat
`sink 100 is disposed.
`Because heat sink 100, e.g., as in the example embodiment,
`preferably is sufficient to dissipate and/or distribute heat gen-
`erated by light 10' lmder normal operation and fault condi-
`tions without having an exposed surface or being attached to
`a highly themrally conductive case or housing. Thus, the case
`or housing of light 10, 10' need not be made of a thermally
`conductive material
`
`Typically, certain external surfaces ofheat sink 100 may be
`shaped to confomr to the inside configuration of a case or
`housing, e.g., in the example embodiment, elongated mem-
`bers 130 are extended and have curved outer surfaces to
`conform to the height and shape of a housing that has a flat
`rear surface and curved side surfaces. Such housing may have
`a flat top surface through which actuator 322 of switch 320
`may be actuated, either directly or through a flexible boot or
`button.
`
`FIG. 4 is an exploded isometric view of heat sink 100 and
`LED assembly 200 ofthe example embodiment ofa light 10'
`according to FIGS. 1-3. Heat sink 100 and LED assembly 200
`are described above and so that description will not be
`repeated here except in relation to certain features more evi-
`dent in FIG. 4.
`
`First generally rectangular member 110 is seen to have a
`raised circular feature 112 on the front face thereof which
`provides a convenient flat surface on which to attach LED
`assembly 200. Because raised circular feature 112 increases
`the thickness of generally rectangular member 110, it also
`reduces the thermal resistance and increases the themral mass
`of heat sink 100. A bevel may be provided along the edge
`where first and second generally rectangular members 110,
`120 join, which increases the thermal mass and reduces ther-
`mal resistance therebetween.
`
`Second generally rectangular member 120 is seen to have
`a generally planar raised area 122 against which one end of
`circuit board 3 00 may bear, preferably the end ofcircuit board
`300 that carries electronic components that generate heat
`under normal operation and/or under fault conditions. Slot or
`hole 124 therein is for receiving fastener 305 which attaches
`circuit board 300 to second generally rectangular member
`120. Raised ridge 126 may be flat at its top and may provide
`support for circuit board 300 in a region thereof under elec-
`trical switch 320 so that circuit board 300 can withstand any
`stress caused by auserpressing on actuator 322 ofswitch 320.
`Area 122 and ridge 126 define a recess 125 therebetween and
`ridge 126 and elongated member 13 0 definea recess therebe-
`tween that may provide clearance between second generally
`rectangular member 120 and circuit board 300 for leads of
`electronic components and solder areas of circuit board 300.
`Because raised area 122 and raised ridge 126 increase the
`thickness of second generally rectangular member 120, they
`also reduce the themral resistance and increase the themral
`mass of heat sink 100.
`
`LED assembly 200 comprises LED 210 and electronic
`circuit board 220. LED 210 is preferably an LED that pro-
`duces substantial light so as to be useable for general illumi-
`nation, e.g., as a flashlight. LED 210 is preferably a white
`emitting LED and is typically rated as a one-watt LED or
`greater. LED 210 is typically provided by the manufacturer in
`the form ofan integrated package including a smallheat sink,
`e.g. a themrally conductive disc, on which the actual diode
`element that emits light is mounted and encapsulated in clear
`
`10
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`20
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`30
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`40
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`UIUI
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`60
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`8
`plastic to provide a lens, and from which two electrical con-
`tacts 212, 214 extend for making electrical connection to the
`diode element.
`Electronic circuit board 220 typically has two conductive
`areas 202, 204 to which electrical contacts 212, 214 of LED
`210 are electrically and mechanically connected, e.g., by
`soldering or by electrically conductive adhesive, so that LED
`210 and circuit board 220 are attached to each other and may
`be handled as an assembly 200. Conductors 340 may be
`electrically connected to conductive areas 202, 204 of circuit
`board 220, e.g., by soldering or by electrically conductive
`adhesive. Circuit board 220 is conveniently circular in shape
`and has a central opening 206 into which LED 210 is disposed
`when contacts 212, 214 are connected to conductive areas
`202, 204. Specifically, the integral heat sink of LED 210 is
`disposed in opening 206 so that it is exposed at the rear of
`LED assembly 200 and may be bonded to circular area 1 12 of
`heat sink 100.
`LED assembly 200 is preferably attached to circular area
`112 of first generally rectangular member 110 of heat sink
`100 by bonding with a themrally conductive adhesive so as to
`provide for the conduction ofheat from LED 210 to heat sink
`100, thereby to reduce the temperature to which LED 210
`rises when energized to less than, e.g., 200° C. Desirably,
`because LED 210 is exposed at the rear of LED assembly 200
`through opening 206, the hart sink integral to LED 210 is
`themrally bonded directly to heat sink 100,
`thereby to
`increase heat transfer from LED 210 to heat sink 100. It is
`noted that circuit board 220 maybe provided for convenience
`in assembly and attachment of LED 210 to heat sink 100 and
`in making electrical connections to LED 210, but circuit
`board 220 is not necessary to the satisfactory operation of
`light 10, 10' as described.
`LED 21 0 is desirably placed in a predetemrined location on
`heat sink 100 so that when hart sink 100 is in light 10, LED
`210 and reflector 30 of light 10 will be in desired relative
`positions for producing a beam of light of a desired shape.
`Proper relative positioning may be provided by positioning
`and bonding LED 210 on heat sink 100 within suitable toler-
`ance, and by positioning hart sink 100 in light 10 within
`suitable tolerance. To this end, heat sink 100 may include
`alignment features, e.g., alignment holes 116, to aid in prop-
`erly positioning LED 210 in relation to heat sink 100.
`For example, heat sink 100 may include two or more align-
`ment holes 116 the locations of which are accurately