Slashdot Mirror
Heat Insulators for Laptops
Alex Bischoff writes "The Gadgeteer has a review of a product called LapPads from LapLogic. They're heat-insulating pads to protect you from cooking your lap when using your laptop. Depending on the model, they apparently provide up to 57 degrees (F) reduction in heat transfer. Why didn't someone think of this sooner?"
I'm sure this guy is really wishing this would have been made sooner...
Then again, if it were out at the time, would he have used it?
The first thing I thought on reading this headline was, Where does the heat that used to be dissipated in the user go?
It appears that there is a textured surface on the pad, one might assume to allow SOME airflow. However, the reviewer was using it wrong:
(Of course, any hardware that uses the operator as a heat-sink is ASKING to lose.)
How does the Slashdot Effect happen given that no slashdotters ever RTFA?
I use one of those cookie sheets with the insulating air space between two sheets of steel/aluminum/whatever. Provides a big dissipation area, the underside is warm but not roasty-toasty, and it cost about $4...
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Which, while not ideal, is marginally preferable to cooking your genitals.
What about the CoolPad?
I've had one for my iBook since early 2002 and it's great for that kind of thing. The swivel feature is neat when I'm working with someone and want to show them something on the screen.
I am not who I say you are.
They're called towels.
Have you read my blog lately?
Is the laptop SUPPOSED to be bleeding heat through the case rather than the fan vent out the back anyway?
A hot computer on my lap is the only action I get.
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Cooler laps are well and good, but I note the reviewer didn't do any analysis of what happened to the CPU temperature when using these pads. If the heat is being redirected right back at the laptop, it may be defeating the coolant systems on the laptop.
For example, Dell Inspirons have a fan on the bottom that blows straight down. Not bad on a hard desk where the air will blow away. Not good on a bed comfortor that smothers the airflow. Where will these pads fit in on the spectrum?
I think what's needed is a pad that works to draw the heat away from both lap and laptop, maybe something like the Chillow for laptops.
57 degrees reduction in surface temperature doesn't just depend on the pad, it assumes a a laptop with certain thermal characteristics and surface area and power use. It could be any laptop, since they don't tell you which, so they might as well be pulling the number out of their ass. The thermal resistivity of a planar surface should just be quoted in watts per degree celcius per square centimeter, ok? This is ridiculous. It reminds me of the History channel talking about "pounds of energy" in a wave. Get the units straight or you might as well be pulling a number out of your ass.
Hey, for some of us, the laptop and the genitals are in symbiosis - neither would get much use without the other.
The delicate balance of this relationship is mediated by DSL, screen cleaner and paper towels.
I have a Case Logic neoprene laptop sleeve that protects my laptop when I throw it into my backpack, and doubles as a lap protector. The neoprene is a very good insulator, and this is much more useful than a dedicated laptop crotch protector.
* mild mannered physics grad student by day *
* daring code hacker by night *
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Because most of us wear pants when using a laptop?
sulli
RTFJ.
Rangefinders for cars? Durr, what about oncoming traffic--it'd make your car flip out! Robotic vaccuum cleaner? Hah hah, what about my stairs? Hard-drive based music player? What if you drop it? Wouldn't it a-splode? Drinking straw? What if you accidentally put it up your nose instead of in your mouth? Huh? What then? Chaos!
Reading the FA aside, does it ever occur to people that a company in the business of making heat-dissipating pads specifically designed to work with laptops just might take the internal temperature of the laptop into consideration? Do people really think that products are designed by an army of Mr. Magoo clones?
Yeah, design mistakes happen, but seriously--if you're able to think of a potential problem after ten seconds' worth of thought, do you really think it likely that the design team wouldn't have considered the exact same thing?
Obliteracy: Words with explosions
it never hurts to RTFA though, or research this before posting opinions. laplogic claims the CPU will run cooler or as cool as on a table.
it's somewhat disappointing that they didn't dramatically improve the cooling as well though.
My laptop is my birth control method
I think that goes without saying in this crowd...
Whether or not that was the best design for dissipating heat is a separate discussion for another day. The fact remains that the laptop *is* dissipating heat this way, and the designers of the pad *know* it, and they are knowingly circumventing it.
Yes. One reason Apple switched from plastic to Titanium (and later Aluminium) is because they were having trouble dissipating the heat from the G4. Plastic doesn't conduct heat that well, but metals do. (I bet most of the pots in your/your mom's kitchen have some aluminium in them. Mine have little aluminium discs on the bottom. Except for the ones that are cast iron.)
I'm in the hole of the broadband donut.
Heat transfer is not measured in degrees! Here's a quick thermal lesson for you electrical guys....
Temperature rise is equivalent to voltage or potential.
Heat flow (Q) in Watts is equivalent to current in amps
Thermal resistance, measured in Degrees per Watt is the same as resistance measured in ohms.
The equations work the same way too. For most instances of steady state heat dissipation what you have is a constant power dissipation or in electrical terms a constant current. The thermal circuit in this case has the heat generating components at V+ and the room can be considered to be ground. There are resistances in the path and the the higher the resistance, the higher the temperature rise there is between nodes.
What this blanket does is to stick a high thermal resistance between the laptop and one of the heat paths and as a result there is a higher "potential".
But indeed the "current" (or watts) is still constant, so by increasing the resistance through one of the paths, you increase the current flowing through the other paths (and as you know from electricity for a constant resistance, will result in higher voltage across those resistances.
So yes, you keep you lap cool... at the expense of the components in your laptop. Be careful what you wish for.
-S
--- What parts of "shall make no law", "shall not be infringed", and "shall not be violated" don't you understand?
A cell phone is a good example of a case that must purely disapate its own heat. Most cell phones would benefit (structurally speaking) from a thicker case. In fact, I've seen design engineers at at least one major mobile phone maker that constantly want to double and triple the size of the "ribs" that reinforce the B-class interior surfaces. This is followed, everytime, by an engineering analyst who's bitching about the fact that the new plan will fry all the electronics.
If the case was nearly a perfect insulator, and the fan was responsible for pushing all the hot and cool air in and out of the case, you'd have a laptop that sounded like a small jet engine. ;-)
I downloaded a program for Toshibas thats runs the fan all the time - keeps the laptop cooler - uses a bit more juice I suppose - but who really uses bateries for anything more than shoulder strain?
cost is $2 - save yourself the $45 dollar (with shipping) silly thing
AIK
The website states:
"LapLogic specializes in Laptop Desks & LapPads that provide up to 57F protection from laptop heat without increasing CPU temperatures. In fact, with our Traveler LapPads,
your CPU will actually run cooler! "
If the heat is "bounced back" into the laptop, how is the CPU running cooler?
The current generation of Aluminum PowerBooks doesn't run hot. A little warm, yes, but you need that on those cold summer San Francisco nights.
sulli
RTFJ.
Quoting from Laplogic:
/.logic.
"Traveler LapPads - 54F of Heat Protection and Cooler CPU Temperatures
Our Traveler Series LapPads are designed to keep you and your laptop cool. The Traveler Series LapPads can provide up to 54F of laptop heat protection for you while keeping your CPU cooler."
It's not that hard to dispel
Who moderates the meta-moderators?
Put a 3 ring binder in your lap and the computer on top. It works perfectly.
The air space between the covers prevents the transfer of heat.
I figured this out through trial and error.
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Several laptops (I know for sure Dell and Toshiba anyway) are designed to work properly on a flat smooth surface. That is, they have either an input or output vent which is supposed to be kept just above the desk surface by little feet. Those of us keeping it on our laps defeat this and become perfect candidates for some type of platform... be it a pad or a phone book.
Circumventing a heat transfer mechanism? Isn't that outlawed by the DMCA?
I made my lap heat shield out of a car sun blind. 1. Buy car sun blind (any gas station or car parts store. about $10). It's a folded piece of foam covered in a metalic film, the size of a windshield. 2. Cut to size. 3. Tape/glue to bottom of laptop. 4. ??? 5. profit! Usually there's no need to cover the whole bottom of the laptop, just the part that generates the most heat (use hand to find it). Haven't noticed any ill effect of the heat shield on the laptop's performance. Why don't they just build them like this? Maybe with an internal heat shield.