Apparatus for deforming thermoplastic material using RF heating

Abstract

A dielectric mold member has different thicknesses producing different radio frequency (RF) voltage drops thereacross. An RF electrode is spaced differently from a thermoplastic sheet to be dielectrically heated by the RF energy such that in one implementation the sheet receives uniform potentials and is heated uniformly. In other implementations, the sheet can receive selectively controlled heating over different regions. In an alternative embodiment, multiple pairs of electrodes apply different RF field levels to different portions of the thermoplastic sheet to compensate for the different voltage drops due to different mold thicknesses or to applied different controlled heating levels to different regions.

Dependencies are inferred from the claim text.