PURPOSE: To eliminate the erasion current at the time of video recording, to decrease the number of circuit parts and at the same time to reduce the power consumption of a VTR, by using a permanent magnet erasion head for full-width erasion and attaching and detaching the erasion head to the tape surface by means of a solenoid.
CONSTITUTION: For a permanent erasion head 20, N and S multi-pole reducing alternating magnetic fields are formed on the rubbing surface of a tape 90 in the traveling direction 91 of the tape 90. The number of alternating poles is set at 11. The erasion noises and strains are reduced less as the number of poles increases to the limited head length. The width (d) of the first N and S poles 90-1 and 90-2 is set larger than that of subsequent ones among many alternating magnetic poles. As a result, the erasion factor is secured in response to a recording medium of high reluctance force in particular. About 0.3mm erasion factor is obtained in case a head material uses barium ferrite or strontium ferrite. The head 20 is put on a head pedestal 21 and is brought into contact with the tape 90. The pedestal 21 is attached rotatably to a supporting shaft 22 which is implanted on a main substrate 50.
MIYATAKE NORIO
UENISHI MITSUAKI
