A history question about planar drivers

This isn't rhetorical (i.e. a test):

Who invented magnetic planar speaker drivers as used by Infinity, Apogee, Magnepan, etc.?

I'd be interested in electrostatic drivers too - which preceded the other? Was the magnetic planar driver a development of the electrostatic planar driver, or vice-versa?

There's really no information about their development online, as far as I have been able to find. Does anyone here know?