| 摘要 |
PURPOSE:To prevent the generation of signal distortion due to an external magnetic field by superposing DC current to signal current at the time of recording. CONSTITUTION:Parts 11, 12 are a reproducing head and an erase head respectively and the head 11 has an intermediate point tap and a terminal 13 is set up to +5V. Signals 14'-17' are applied to terminals 14-17 respectively. The signals 15, 16' are data signals, the signal 14' is a write gate signal and the signal 15' is an erase ON signal. When the erase ON signal 15' is the H level, a transistor 24 is turned on, erase current flows into a winding 12 and simultaneously DC current always flows into the lower half winding of a winding 11 through a resistor 25, so that the whole current flowing into the winding 11 is shifted by a DC current component. Consequently, the magnetic field intensity formed by the winding of a recording/reproducing head is also shifted by a DC magnetic field component during the time the erase current flows, so that the magnetic field formed close to the gap of the recording/reproducing head is offset by the erase head. |
