Thread: [WIP] Wireless charging TOH
View Single Post
pichlo's Avatar
pichlo is offline pichlo
2013-12-21 , 07:51
Posts: 6,453 | Thanked: 20,983 times | Joined on Sep 2012 @ UK
#23
Originally Posted by eruanno View Post
<1mm thick, flexible but quite heavy for its volume. Larger than the coil. Can someone tell what this is for? Is it to block the rays going beyond the coil?
It's quite possible, actually. I've never seen it so can't say for sure but my wild guess would be it's there to increase efficiency rather than protect something. Magnetic circuits such as transformers (transformers not transformers - wireless chargers are nothing more than the former in disguise) work best if the magnetic flux leak is kept to the minimum. This is usually achieved by directing the flux through some kind of magnetically conductive material.

btw: Could the electromagnetic field harm any of the other components? I think the field must be pretty strong to charge the battery. What happened, if AC was generated in other parts?
It is possible in theory if the field is powerful and there are circuits in its path with coils inside them, oriented the wrong way. Even a badly designed PCB track can act as a coil. It is unlikely in practice though. Besides, any metal bits (such as the battery compartment in the N900) would divert the magnetic field and act as a shield.