Patent ID: 7027709

Claim:
A method for forming a magnetic gap for a video signal erasure head, wherein: said erasure head comprises a back core made of a magnetic substance which is wound with an excitation coil and a front core arranged opposite to said back core; said front core includes two magnetic substances constituting a magnetic path and a non-magnetic substance providing a magnetic gap arranged therebetween; said magnetic gap forming method comprises the steps of: (a) forming an integrated assembly, which is the front core, by sandwiching a non-magnetic substance providing a magnetic gap between said two magnetic substances, and then adhering said non-magnetic substance to said magnetic substances, wherein said assembly is formed as a block having a size enough to form a plurality of front cores therein at a time, and wherein the magnetic substance has a previously formed groove by cutting in a face providing a head rear side thereof; (b) cutting and dividing said assembly in a direction perpendicular to the face of said non-magnetic substance into a plurality of sub-assemblies having an equal size; and (c) polishing a face providing a front side of said head in said assembly to an axis-symmetrical curved face.