From: firstname.lastname@example.org (Bob Wilson)
Subject: Re: luxeon star leds
Date: Tue, 26 Nov 2002 03:46:13 -0000
Organization: Your Organization
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References: <3DDD9A57.58900EFB@RobertsResearchInc.com> <email@example.com> <3DDDB646.96D0D9D2@RobertsResearchInc.com> <3DDE7264.CD48F4F8@RobertsResearchInc.com> <firstname.lastname@example.org> <3DDEB081.884EC92A@RobertsResearchInc.com> <3DE03D65.932BF9BF@RobertsResearchInc.com> <3DE15871.EF8FF9EA@RobertsResearchInc.com> <3DE224D3.81EFBA3C@RobertsResearchInc.com>
In article <3DE224D3.81EFBA3C@RobertsResearchInc.com>,
>Bob Wilson wrote:
>> In article <3DE15871.EF8FF9EA@RobertsResearchInc.com>,
>> Vic@RobertsResearchInc.com says...
>> >Watson 'Atto Parsec' Name wrote:
>> >> In article <3DE03D65.932BF9BF@RobertsResearchInc.com>,
>> >> Vic@RobertsResearchInc.com talked about...
>> >> > Watson 'Atto Parsec' Name wrote:
>> >> > >
>> >> > > I don't buy this convection from the top because I'm using the
>> >> > > Star/O which has the whole top of the LED covered by the lens
>> >> >
>> >> > You are certainly entitled to your opinion, but don't you
>> >> > think that the lens assembly will have convective losses
>> >> > when it gets hot? The lens assembly will, of course, get hot
>> >> > under steady state conditions if the metal base is not
>> >> > conected to a heat sink. Considering that the lens assembly,
>> >> > including its cylindrical holder, has a much greater surface
>> >> > area than the top of the "bare" Luxeon Star, the "convective
>> >> > effect" should be more pronounced for a Luxeon with the lens
>> >> > assembly than for one without.
>> >> The heat from the aluminum base will conduct up thru the barel of the
>> >> assy and be 'convected' away, as much if not moreso than the internal
>> >That's a good point.
>> Interesting that it is expected that any significant amount of heat will
>> conducted up through an insulating plastic barrel, that is only 1mm
>> Even more interesting how this can be expected to be significant, in view
>> the Luxeon LED itself, being mounted on a metal core PCB, and that being
>> mounted to to a heatsink. Quite obviously any small amount of heat
>> that manages to be conducted up the small cross section of insulating
>> plastic barrel, will be totally insignificant when compared to that which
>> flows through the large area of 0.1mm thick FR4 laminated to the aluminum
>> backing directly behind the metal base of the LED, and directly into a
>You are correct, if the Luxeon were mounted on a heatsink.
>However, this whole discussion started because of some
>unexpected results that were published about a Luxeon that
>was NOT mounted on a heatsink.
Ooops, I missed that. But a luxeon without a heatsink would seem to be a
complete waste of an expensive LED. Without a heatsink, it is not possible
to push it to anywhere near its intended power level, May as well just use