<1»)United States
`(12)Patent Application
`Dahm et al.
`
`Publication
`
`(to)Pub.No.:US 2008/0205062At
`(43)Pub. Date:
`Aug. 28, 2008
`
`US 20080205062A1
`
`(54) MULTIPLE LIGHT-EMITTING ELEMENT
`
`Related U.S.Application Data
`
`HEAT PIPE ASSEMBLY
`
`(76)
`
`Inventors:
`
`Jonathan S. l)ahm. Key I argo_Fl.
`(US); Mark Paul Jongewaard.
`/\r\'ada. CO (US)
`
`Correspondence Address:
`(TOBNOLLY BOVE LODGE & HUTZ LLP
`
`P_()_BQX 1297
`w[LM[NGT0§9 DE 19899 Us
`(
`
`)
`
`(21) App}, N0;
`
`11/849,147
`
`(22)
`
`Filed:
`
`Aug. 31. 2007
`
`(G0) Provisional application No. 60/841.971. filed on Scp.
`l. 2006,
`
`pub|ic,,t1on (j|,,§s1fic,,¢|on
`
`(51)
`
`Int. (El.
`(2006.01)
`F21l' 29/00
`(52) U.S. Cl.
`...................................................... .. 362/294
`(57)
`ABSTRACT
`
`ipvention provildes 5111opgelal dfvipeheotnpirising
`The present
`one or more teat pipes wit 1 21 estrz.
`eve 0 t erma cou­
`pling with the light-emitting elements which are positioned
`along a periphery ofthe evaporator surface portion ofthe heat
`pipe in such u way that they are therntally eoupled to the heat
`pipe. In one embodiment. the heat pipe oi the present inven­
`tion can he readily integrated with optical elements such as
`reflectors or collimators.
`
`J2
`
`'
`
`‘
`
`.\
`_'
`\§.\
`\
`
`-.\_
`t‘
`-
`
`\§
`
`32
`
`i I
`r
`
`20
`
`1
`
`'
`
`.
`
`V
`
`\“'.-my!’
`>‘,.,\uIm‘_
`-
`._’r \‘/
`Z'ir‘t‘i‘i$\\“
`
`I
`I
`
`:
`
`I.
`
`'.
`
`-"
`
`/
`
`/'
`
`5'
`
`_i
`
`,'
`
`:
`
`/1' 1/
`
`’
`
`,
`
`,'
`
`'1
`_|.
`
`/_.'
`f
`1/ ,1
`/­
`.'
`
`20
`
`/'
`.-
`/ _,
`Q Z
`4»,
`"25;
`
`it!
`‘I
`
`E
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Patent Application Publication
`
`Aug. 28»2008 Sheet 1 °f 23
`
`US 2008/0205062 Al
`
`I
`
`ix)!Fl
`
`I
`
`1
`
`I
`
`/I
`
`>//fl
`
`_!
`
`‘ll
`
`/
`
`’
`
`V.
`
`.
`
`I
`
`1/]
`
`A
`
`I
`
`/1’
`\2a
`
`/
`
`|I
`
`,f
`
`I
`
`/
`
`I
`
`*
`
`J
`
`1
`/'
`
`I
`
`/I
`
`/
`
`_
`
`_/
`
`,
`
`ll '/
`/1I
`///;'
`//
`/
`/
`0/
`,
`
`32
`
`[I
`
`K
`
`\
`
`\‘\\
`\
`\
`
`\\\\
`
`\
`
`10
`
`K\\
`
`\\
`
`\
`
`\\\\
`\§\\ \\
`\\
`\
`
`\»\\
`
`\
`
`\
`
`\
`_ ­
`
`\
`
`I‘
`\
`
`\
`\
`Y/
`22""­
`
`V1
`f
`
`f
`
`r
`
`’
`
`/
`
`16
`
`FIG. 1
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Patent Application Publication
`
`Au .28 2008 S
`g
`,
`heet 2 of 23
`
`US 2008/020§062 A1
`
`10
`
`\
`
`\}
`
`\
`
`\i
`
`,
`
`\\\
`
`'
`T
`‘I I
`\\\‘
`
`\
`\
`
`~
`
`\
`
`\
`
`\
`\\
`
`.
`
`\
`
`\
`\‘
`
`\
`
`I
`5
`
`.'
`
`|
`
`.
`
`,
`
`/,-,1
`'
`‘
`"
`.
`a2 >\\\
`/¢ "
`\'=e:s~w,
`'
`I._f
`'¢;:?'.»I'
`$3:-.~-"‘
`aw:
`*\-. 0
`20
`I...
`/
`/
`' _.
`9'-€
`,
`Q
`fiiiiisw‘
`
`/
`
`4'
`
`'
`
`I
`
`I
`
`,
`
`1
`p
`
`I 1
`
`/1
`
`I
`
`-
`
`-‘
`
`1 I/I
`;"
`~
`o
`,/I’
`l,,/
`F
`1/
`
`~'
`,7 )/
`I
`,
`.'
`
`I
`
`1
`
`~
`V
`
`;
`
`1
`
`___ ,4.»-12
`
`FIG. 2 j
`
`

`

`
`
`Patent Application Publication
`
`
`
`
`
`
`
`
`
`Aug. 28, 2008 Sheet 3 of 23
`
`
`
`US 2008/0205062 A1
`
`
`
`
`
`
`FIG. 3
`
`
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Patent Application Publication
`
`Aug. 28, 2008 Sheet 4 of 23
`
`US 2008/0205062 A1
`
`/52
`j~"
`
`1
`
`1 fllflin
`
`¢
`
`60
`
`"/V\~ii
`
`\
`
`n;i_
`
`R
`
`1 \
`
`1
`
`l
`sat
`
`=|
`
`‘E
`
`1
`
`r
`
`/, /'
`'11
`
`FIG. 4
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Aug. 28, 2008 Sheet 5 of 23
`
`US
`
`200810205062 A1
`
`afion Publication
`Patent Applic
`
`310
`
`s
`
`\ \
`\\\
`
`D
`
`315
`
`305
`
`/’ /
`"”\‘§“_h .1»/%
`
`’
`
`'
`
`WIl11~\\|n|\\®®'
`325
`‘
`/‘
`
`zf
`
`/»’
`
`X
`
`-_
`
`,0_0,___km‘w‘22.
`
`2__________'
`
`‘
`
`W
`
`300/ \\
`
`F\G. 5
`
`

`

`Patent Application Publication
`
`Aug. 28, 2008 Sheet 6 of 23
`
`US 2008/0204062 A1
`
`ill!!!
`
`/
`
`*
`
`\ ii. JLili/
`
`325
`
`" WI)”
`
`FIG. 6
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Patent Application Publication
`
`Aug. 28, 2008 Sheet 7 of 23
`
`US 2008/0205062 A1
`
`305
`
`aoo\//////
`Z"Z
`/,/
`./V
`/:l/
`1/'
`,//
`.//,
`/’
`/ /12
`
`FIG. 7
`
`

`

`Patent Application Publication
`
`Aug. 28, 2008 Sheet 8 of 23
`
`US 2008/0205062 A1
`
`
`
`FIG. 8
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIG. 9
`
`
`
`

`

`
`
`Patent Application Publication
`
`
`
`
`
`
`
`
`
`
`Aug. 28, 2008 Sheet 10 of 23
`
`US 2008/0205062 A1
`
`
`
`
`
`
`
`
`
`
`FIG. 10
`
`
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Patent Application u 1
`P bl'cati0n
`
`Aug. 28, 2008 Sheet 11 of 23
`
`US 2008/0205062 A1
`
`425
`
`v.=_._,
`
`405
`
`4
`
`~
`
`_T_
`
`\\>
`\ \\\>»\\
`t\3\*\
`
`\<
`
`17
`
`H,
`
`\
`
`\
`
`i
`
`'
`
`,_..
`
`'
`
`‘
`
`/
`
`/
`
`FIG. 11
`
`

`

`
`
`Patent Application Publication
`
`
`
`
`
`
`
`
`
`
`Aug. 28, 2008 Sheet 12 0f 23
`
`
`
`US 2008/0205062 A1
`
`
`
`
`
`
`. FIG. 12
`
`
`
`

`

`
`
`Patent Application Publication
`
`
`
`
`
`
`
`
`
`
`Aug. 28, 2008 Sheet 13 0f 23
`
`
`
`US 2008/0205062 A1
`
`
`
`
`
`
`
`
`
`
`
`
`FIG.13
`
`

`

`
`
`Pttttt Application Publication
`
`
`
`
`
`
`
`
`
`
`Aug. 28, 2008 Sheet 14 0f 23
`
`
`
`US 2008/0205062 A1
`
`
`
`
`
`
`FIG. 14
`
`
`
`App
`
`A g s
`
`00s s
`
`4 £23
`
`s 00s/0 0500 A
`
`O
`
`vv”?
`
`1
`
`__<%gig??? E
`
`my
`4,!/\]F
`
`FIG. 14
`
`

`

`Patent Application Publication
`
`
`
`
`
`Aug. 28, 2008 Sheet 15 of 23
`
`
`
`
`
`
`
`
`US 2008/0205062 A1
`
`
`
`
`
`I
`
`;‘I..5;“““:- ‘
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`\1':1~;:'
`
`
`
`
`
`ik‘
`
`
`
`
`
`
`
`
`
`
`E.'
`
`\\\\
`\iIi
`
`

`

`
`
`Patent Application Publication
`
`
`
`
`
`
`
`
`
`
`Aug. 28, 2008 Sheet 16 0f 23
`
`
`
`US 2008/0205062 A1
`
`
`
`
`
`
`
`
`FIG. 16
`
`
`
`

`

`Patent Application
`
`Publication
`
`Aug. 28, 2008 Sheet 17 of 23
`
`US 2008/0205062 A1
`
`
`
`FIG. 17
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Pubhcatlon
`
`g. 28, 2008 She
`
`F‘ /WU %"
`
`\:
`
`FIG. 18
`
`

`

`Patent Application Publication
`
`Aug. 28, 2008 Sheet 19 of 23
`
`US 2008/0205062 Al
`
`'
`
`f
`
`*-A
`
`A‘
`
`I
`
`5
`
`Hy
`
`‘mull
`
`\\I"V!/
`
`.
`
`_
`
`=’
`
`‘!~--
`
`.-_;I}
`
`I
`
`i
`
`l
`
`I
`
`5\
`
`r
`
`J
`
`|‘
`
`’é
`
`I x
`
`802
`
`801
`
`I
`
`F|G.A19
`
`

`

`20 of 23
`
`us 2008/0205062 A1
`
`805
`
`I
`
`.
`
`1
`
`Aug. 28, 2008 Sheet
`
`I,4
`
`/
`
`xy‘
`
`|
`
`f
`
`FIG. 20
`
`Patent Application Publication
`
`

`

`\ 4
`/\
`
`Patent Application Publication
`
`Aug. 28, 2008 Sheet 21 of 23
`
`US 2008/020§062 Al
`
`"
`
`FIG. 21
`
`

`

`Patent Application Publication
`
`Aug
`
`. 28, 2008 Sheet 22 of 23
`
`US 2008/0205062 Al
`
`605
`
`L}
`
`I
`
`\_\
`
`600
`
`FIG. 22
`
`

`

`Patent Application
`
`Publlcauon
`
`Aug 28 2008 Sheet 23 of 23
`
`US 2008/0205062 Al
`
`'0
`
`i
`
`\
`
`\I
`
`!
`
`/
`
`I
`
`I
`
`600--Y
`
`iJ
`
`625 615
`
`°°5
`
`\1:~‘
`
`_m
`
`_ >'
`
`l
`
`'
`
`i
`
`I
`
`.
`
`‘
`
`r; i
`
`!-
`‘V?
`
`_"'
`
`‘
`
`.
`
`,
`
`ll
`
`;~
`|‘
`
`~
`
`J_a
`
`FIG. 23
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`US 2008/0205062 A 1
`
`Aug. 2s, 2008
`
`lVfUI.TIPI.FlIJGI-IT-ENIITTIYG ELEMENT
`HEAT PIPE ASSEMBLY
`
`fill-JLDOl‘ THE lNVl:'NTlON
`
`[0001] The present invention pertains to thermal manage­
`ment oflight-emitting elements a11dmore particularly to an
`assembly comprising one or 111oreheat pipes for thermal
`management of multiple light-emitting elements.
`
`BACKGROUND
`
`[0002] Luminaires are employed in a number of lighting
`applications, such as ambient or space lighting, accent light­
`ing, wall washing. signage. advertising. decorative and dis­
`play lighting, facade lighting, and custom lighting. Lumi­
`naires typically include a number of high-brightness
`incandescent,
`fluorescent, neon, or light-emitting diode
`(LEDs) type light sources coupled to a power ma11age111ent
`system for supply of energy and control of the desired utility.
`[0003] A general drawback ofhigh-brightness light sources
`includes the release of excessive quantities of heat under
`operating conditions. While being relatively efficient certain
`LEDs offer high energy densities and generate large amounts
`of Waste heat in small spaces. The use of high-brightness
`Ll:'Ds in illumination applications usually requires some
`form of temperature control to mitigate the risks of cata­
`strophic failure modes of the I_EDsand other components of
`the lu111i11aire.
`[0004] Temperature control of I_EDscan entail maintaining
`sub-optimal operating conditions below nominal power rat­
`ings or, alteniatively, improving the rate at which heat can
`dissipate from the LED or another heat source to a cooler
`environment. There are a number of solutions known inthe art
`including active and passive cooling including heat sinks and
`heat pipes. Ileat sinks comprise heat-conductive elements
`that can be thermally coupled to a heat source. The heat sink
`needs to be thermally coupled to the heat source and the
`environment; the coupling between the heat sink and the heat
`source is typically of a conductive nature and the coupling
`between the heat sink and the environment is typically con­
`vective i11 nature. Heat sinks provide large surfaces
`to
`improve cooling efficiency via thennal convection in a proxi­
`mate space oftl1e environment. Heat sinks typically include a
`large number of structural cooling elements such as fms, pins
`or posts to increase the surface area between the heat sink and
`the enviromnent. l-‘orcedconvection via fans, for example,
`ca11be employed to improve convection and increase the
`efficiency of the heat sink.
`[0005] Heat sinks are widely employed for Lhe thermal
`management of ltuninaries but their form and use have lim­
`ited applicability for the direct cooling of LEDs as i11terfer­
`ences with the light emission ofthe LEDs are usually undes­
`ired. Heat sinks provide limited heat dispersion capabilities
`a11doccupy relatively large spaces in order to work effec­
`tively. Heat sinks can only be employed Where they can be
`adequately thermally coupled to LEDs or other heat sources
`a11dmay therefore be excluded from use i11systems with high
`device integration densities.
`[0006] A heat pipe is another type oftherrnal management
`device. Ileat pipes comprise a thermally conductive body in
`which a certain amount of a heat transfer medium such as a
`gas, liquid or other lluid is hermetically contained. Heat pipes
`are intended to rapidly transfer heat from one end to another
`end of the heat pipe while being relatively small. One end of
`
`the heat pipe is thermally coupled to a heat source and the
`other end can be thennally coupled to a device of lower
`temperature. One end of the heat pipe typically absorbs ther­
`mal energy generated by the heat source, initiating the tem­
`perature inside the heat pipe to rise which can cause the heat
`transfer medium inside the heat pipe to undergo a phase
`transition. for example the heat transfer medium may evapo­
`rate. As a result, Lhe absorbed heat from the heat source
`provides the energy to overcome the latent heat of the phase
`transition of the heat transfer medium which i11return pro­
`vides an effective cooling mechanism. Typically the heat
`transfer medium evaporates and diffuses or buoys away from
`the heat source, through one or more cavities Withinthe heat
`pipe to reach a cooler end ofthe heat pipe where it condenses.
`Transport of the condensate back to the hot end of the heat
`pipe is usually either gravitational or aided by capillary
`effects. Fnhanced capillary effects can originate from addi­
`tional elements which can be disposed inside certain types the
`heat pipes for example a Wicking structure. The condenser
`end ofthe heat pipe can be cooled via coupling to a heat sink,
`for example.
`[0007] Many known heat pipe designs suffer from a num­
`ber of deficiencies. Effective heat pipes cannot be built arbi­
`trarily small and often require additional elements such as
`heat transfer plates when used for cooling relatively small
`devices in highly integrated systems. Generally, the integra­
`tion of heat pipe cooling technology in tightly-packaged
`luminaries can be dillicult. Additionally, the charging ofheat
`pipes with cooling media may require controlled pressure
`conditions during manufacturing.
`lt is diflicult
`i11standard
`heat pipe integration designs to mold heat pipes along with
`injection molded parts of the luminaire such as optical ele­
`ments, for example.
`[0008] Furthermore, every additional component included
`i11the thermal management system increases the complexity
`of the system design, decreases cost effectiveness and also
`introduces additional interfaces which can act as a heat flow
`barrier which can significantly reduce the overall cooling
`eificiency. For example, LED dies can be mounted on a sub­
`strate which ca11be thermally coupled to a heat spreader plate
`which itself in return can be thennally coupled to a heat pipe
`and so forth. Each of these elements needs to be in intimate
`thennal contact with its adjacent element for the cooling
`system to work effectively.
`[0009] There is therefore a need for a thermal management
`system that offers improved heat transfer elficiency and
`which can be integrated with optical elements and suitable for
`use i11LED-based luminaries.
`[0010] This background information is provided to reveal
`information believed by the applicant to be of possible rel­
`evance to the present invention. No admission is necessarily
`intended, nor should be construed. that any of the preceding
`information constitutes priorart against the present invention.
`
`SUMMARY Ol‘ THE lNVl:'NTlON
`
`[0011] An object of the present invention is to provide a
`multiple light-emitting element heat pipe assembly. l11accor­
`dance with one aspect of the present invention, there is pro­
`vided an optical device comprising: a heat pipe having an
`evaporator end portion having a perimeter; one or more light­
`emitting elements for generating light, the one or more light­
`emitting elements operatively and thermally coupled to the
`heat pipe at the perimeter of the evaporator end portion.
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`US 2008/0205062 A 1
`
`Aug. 2s, 2008
`
`In accordance with another aspect of the present
`[0012]
`invention, there is provided an optical device comprising: a
`plurality of heat pipes each having a evaporator end portion
`having a perimeter and each of the heat pipes having a c011­
`denser end portion, wherein each evaporator end portion of
`the heat pipes has a cross sectional shape configured to enable
`compact proximate positioning ofthe evaporator end portion
`of each of the heat pipes and wherein each of the plurality of
`heat pipes are configured to provide spatial separation of each
`condenser end portion of the heat pipes; one or r11oreligl1t­
`emitting elements for generating light, wherein one or more
`light-emitting elements are operatively and thennally
`coupled to each of the heat pipes at the perimeter of the
`evaporator end portion.
`
`BRIEF DESCRIPTION OF TIIE FIGURES
`
`[0013] FIG. 1 illustrates a side view of an optical device
`according to an embodiment of the present invention.
`[0014] FIG. 2 illustrates a perspective view of the optical
`device illustrated in FIG. l.
`[0015] FIG. 3 illustrates a detailed perspective view of the
`optical device illustrated in FIG. l with the optical element
`removed.
`[0016] FIG. 4 illustrates a side view of a heat pipe and
`substrate of an optical device according to another embodi­
`ment of the present invention.
`[0017] FIG. 5 illustrates a perspective view of an optical
`device according to another embodiment of the present inven­
`tion.
`[0013] FIG. 6 illustrates a top view ofthe optical device of
`FIG. 5.
`[0019] FIG. 7 illustrates a perspective view of a heat pipe
`and light-emitting element of the optical device of FIG. 5.
`[0020] FIG. 8 illustrates a perspective View of an optical
`device according to another embodiment of the present inven­
`tion.
`[0021] FIG. 9 illustrates a top view of the optical device of
`FIG. S.
`[0022] FIG. 10 illustrates a perspective view ofa portion of
`the optical device of FIG. 8.
`[0023] FIG. 11 illustrates a perspective view of a portion of
`the optical device ofFIG. 8.
`[0024] FIG. 12 illustrates a perspective view of an optical
`device according to another embodiment of the present inven­
`tion.
`[0025] FIG. 13 illustrates a perspective view ofa portion of
`the optical device of FIG. 12.
`[0026] FIG. 14 illustrates a top view of the optical device of
`FIG. 12.
`[0027] FIG. 15 illustrates a perspective view ofa portion of
`the optical device of FIG. 12.
`[0023] FIG. 16 illustrates a perspective view ofa heat pipes
`and light-emitting element of the optical device of FIG. 12.
`[0029] FIG. 17 illustrates a perspective view of a11optical
`device according to another embodiment ofthe present inven­
`tion.
`[0030] FIG. 18 illustrates a top view of the optical device of
`FIG. 17.
`[0031] FIG. I9 illustrates a perspective view ofa portion of
`the optical device of FIG. 17.
`[0032] FIG. 20 illustrates a perspective view of a heat pipe
`and light-emitting element of the optical device of FIG. 17.
`
`[0033] FIG. 21 illustrates a perspective view ofa portion of
`an optical device according to another embodiment of the
`present invention.
`[0034] FIG. 22 illustrates a perspective view of a heat pipe
`and a light-emitting element of the portion of the optical
`device ofFIG. 21.
`[0035] FIG. 23 illustrates a perspective view ofa portion of
`an optical device according to another embodiment of the
`present invention.
`
`DETAILED DESCRIPTION OF THE INVENTION
`
`Definitions
`
`[0036] The term “light-emitting diode” (LED) is used to
`include a general or specific type of LED or laser diode such
`as resonant cavity LED (RCLED), superluminescent LED
`(SLLED), organic LED (OLED), fiexible OLED (FOLED),
`Flip Chip LED (FCLED), high-brightness LED or other LED
`as would be readily understood by a worker skilled in the art.
`[0037] The tenn “light-emitting element” (LEE) is used to
`define a device that emits radiation in a region or corrrbination
`of regions of the electromagnetic spectrum for example, the
`visible region. infrared and’or ultraviolet region, when acti­
`vated by applying a potential difference across it or passing a
`c1.u"rentthrough it, for example. Therefore a light-emitting
`elen1e11tcar1 have monochromatic, quasi-monochromatic,
`polychromatic or broadband spectral emission characteris­
`tics. Examples of light-emitting elements include semicon­
`ductor, organic, or polymer/polymeric light-emitting diodes,
`optically pumped phosphor coated light-emitting diodes,
`optically pumped nano-crystal light-emitting diodes or other
`similar devices as would be readily understood by a worker
`skilled in the art. Furthermore, the term light-emitting ele­
`ment is used to define the specific device that emits the radia­
`tion. for example a LED die, and can equally be used to define
`a combination of the specific device that emits the radiation
`together with a housing or package within which the specific
`device or devices are placed.
`[0038] The term “optical element” is used to refer to lenses,
`filters, reflectors, prisms etc that affect the propagation or
`composition of light as would be readily understood by a
`worker skilled in the art.
`[0039] As used herein. the term “about” refers to a +/—10%
`variation from the nominal value. It is to be understood that
`such a variation is always included in any given value pro­
`vided herein. whether or not it is specifically referred to.
`[0040] Unless defined otherwise, all technical and scien­
`tific terms used herein have the same meaning as commonly
`understood by one of ordinary skill in the art to which this
`invention belongs.
`[0041] The present invention arises from the realization
`that existing optical devices having a heat pipe for cooling
`li@t-emitting diodes suffer from the disadvantage that the
`heat pipe is typically not in intimate thermal contact with the
`I.F.Ds and cannot be easily integrated with the I.FDs, the
`optical elements and the drive circuitry of a luminaire because
`they would either obstruct or otherwise undesirably affect the
`desired light emission or the desired placement of a driving
`circuit therefor. The present invention provides an optical
`device comprising one or more heat pipes with a desired level
`of thennal coupling with the light-er11ittir1gelements. wherein
`the light-emitting elements are positioned along a periphery
`of the evaporator end portion of the heat pipe in such a way
`that they are thennally coupled to the heat pipe. In one
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`US 2008/0205062 A 1
`
`Aug. 2s, 2008
`
`embodiment, the heat pipe of the present invention can be
`readily integrated Withoptical elements such as reflectors or
`collimators.
`[0042] The present invention further provides an optical
`device comprising a plurality of heat pipes configured for
`substantially intimate placement therebetween of the evapo­
`rator surface end portions ofthe heat pipes. One or more light
`emitting elements for generating light are thermally coupled
`to each of the plurality of heat pipes. The one or more light­
`emitting elements are positioned substantially proximate to
`the periphery of the evaporator end portion of the heat pipe.
`The relative positioning and configuration of the heat pipes
`can enable the reduction of the cross sectional size of the
`region required for the light-emitting elements, while reduc­
`ing impediments to the desired light emission for the optical
`device. In one embodiment, the heat pipe of the present inven­
`tion ca11be readily integrated with optical elements sucl1as
`reflectors or collirnators.
`[0043] FIG. 1 and FIG. 2 illustrate an optical device 10 in
`accordance with an embodiment of the present invention. Tl1e
`optical device 10 includes a heat pipe 12 having a11i11tem1e­
`diate bulk portion 14, a condenser surface 16 at one end
`region of the bulk portion 14, and a evaporator surface 17 at an
`opposite end region of the bulk portion 14. A portion of the
`bulk portion 14 adjoining the condenser surface 16 may also
`act as a condenser surface. A number of light-emitting ele­
`ments 20 are positioned on a substrate 22 wherein the sub­
`strate 22 is in thermal contact with the evaporator surface of
`the heat pipe 12. The optical device ftuther comprises an
`optical element 28 for the collection, blending and redirection
`ofthe light emitted by the light-emitting elements. The opti­
`cal element 28 can be directly or indirectly attached to the top
`of the substrate or the light-emitting elements, for example.
`[0044]
`In one embodiment of the present invention, the
`optical device is configured to minimize the etendue thereof.
`As is known the etendue ofan optical device is a constant and
`is calculated as the product of the opening size of the optical
`device and the solid angle from which the optical device emits
`light. The optical device according to t_hepresent invention is
`configured such that the light-emitting elements are mounted
`in relation to the heat pipe in a configuration that is substan­
`tially a11optimal balance between opening size and the ther­
`mal path length between the light-emitting elements and the
`sidewall wicking structure of the heat pipe. The circurnfere11­
`tial configuration ofthe light-emitting elements according to
`one embodiment of the invention has an area that is about
`10-20% larger than the area that Wouldresult from mounting
`the light-emitting elements in a square configuration Which
`included the area defined by a circular reflector around the
`light-emitting elements.A square configuration of light-emit­
`ting elements. however, would likely he impractical for elec­
`trical interconnections such as wire bonds. Additionally, in a
`square configuration, the concentration of thermal energy in
`the central region of the tip of the heat pipe may result in the
`wicking structure of the heat pipe in this central region drying
`out, thus resulting in a longer thermal path length to the
`wicking structure positioned along the interior ofthe walls of
`the heat pipe. In addition, this circumferential configuration
`of the light-emitting elements may reduce thermal cross talk
`between the light-emitting elements and may provide a more
`equal distance between the light-emitting elements and a
`centrally located optical sensor. Finally, color mixing can be
`increased by arranging the circumferentially positioned ligl1t­
`
`emitting elements in such a way as to essentially ensure that
`li@t-emitting elements of similar emission wavelengths are
`separated sufliciently.
`
`IIeat Pipe
`
`[0045] The bulk portion of a heat pipe defines a tubular
`hollow body which is partially filled with a certain amount of
`cooling medium, for example ammonia, water or the like.
`Whenever cooling medium proximate to the evaporator sur­
`face evaporates, it migrates inside the heat pipe towards the
`condenser s1u’faceWhere the cooling medium condenses if
`the inside of the heat pipe proximate to the condenser surface
`is of adequate temperature.
`[0046] The condenser s1u’facecan be left exposed to the
`environment or it can be thermally coupled to a heat sink for
`cooling ofthe condenser surface. Under operating conditions
`the heat pipe comprising the intermediate bulk portion, con­
`denser surface and evaporator surface can form a thermally
`conductive path for dissipating heat removed away from heat
`sources such as light-emitting elements which are thermally
`coupled to