They call it lid cooling, and it works like this. In a normal laptop, the heatpipes over the CPU pull off energy and transfer it to a heatsink. A fan then sucks in air and blows it at high speed over the heatsink. As laptops get thinner and hotter, this means higher speed air, less efficient heatsinks, and in general, lots of noise. It also takes power to move that air, so it drains battery life in addition to being annoying.

Compal, as you can see above, has a much better solution. The heatpipe pulls the energy off, and that is routed through the hinge and on to a big aluminum or carbon plate that backs the screen. The lid looks like any other, just a normal laptop, and under full load, feels a little warmer.

The big trick here is the hinge, you need something that works like a normal hinge, transfers heat and is totally reliable. This is not a minor engineering challenge, but Compal claims to have done it.

The results are that the system can dissipate the heat from a 17W CPU, about half of the worst case energy from a high end 35W laptop part. Since you almost never pull the full TDP from a CPU, unless you are really pounding it, you will almost always be able to run fan free on this system.

It can have a backup fan to supplement the cooling if needed, but if you keep power under the 17W cap, you can have a totally sealed laptop. Why does this matter? Think dust, the silent killer of laptops everywhere (read that again in a WWII anti-VD army film voice). Sealed laptops don't collect dust internally and better yet, don't have a fan to collect dust on.

The screen is said to be capped at 50c temps, quite warm but not unacceptable. The two demo systems Compal had at IDF were mildly warm, you could tell they were hotter than ambient, but if you didn't know the screen was a radiator, you would not have thought anything was out of the ordinary.

One last note, I think there is one thing that Compal missed, and I hope to see in Gen 2 lid cooling, convection based cooling. Instead of having the heat plate covered by insulating plastic, put a gap between the cover and the plate with vents at the top and bottom. When the laptop is on, convection currents should pull cool air in the bottom and exhaust hot air out of the top. Free air conditioning, and on top of it, you get an insulating air gap to the lid.

I really hope this technology succeeds, it will make a huge difference in laptop reliability, battery life and acoustics. Other than cost and potential reliability, there is no down side to this and several big up sides. This is by far the most significant technology I have seen at the show. µ