Hill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson
Static magnetic erasing head
 A magnetic erasing head for magnetic recording apparatus using a static magnetic field. The erasing head includes at least three magnetic poles all of which are arranged to scan the same recorded track on the tape. The first and third poles have the same polarity while the second pole has opposite magnetic polarity. The first pole is arranged to engage the full width of the track and magnetizes it with one polarity. The second pole faces the upper half of the track and magnetizes it with the opposite polarity. The third pole engages the lower half of the track and magnetizes it with the same polarity as the first pole. After passing by these three poles, substantially one-half of the recording track is magnetized with one polarity and the other half of the track is magnetized with the other polarity so that distortion of output signals is maintained small or eliminated for various magnetic tapes having different coercive force values. 
Sony Corporation
G
G11B
inventional
Nobuyuki Makoto
Murata Saito