| 摘要 |
A magnetic tape degausser includes a pair of electromagnets which are arranged to project a magnetic field through a magnetic tape reel to magnetically erase the magnetic tape. The magnetic tape degausser includes improvements in the control of the motorized transport mechanism used to control the movement of a tape reel in rotation towards and away from erasing electromagnets. Excitation of the electromagnets is synchronized with the operation of the transport mechanism in a cooperative fashion so that the electromagnets are actuated when the magnetic tape is near the electromagnets and as the magnetic tape is withdrawn from the electromagnets. An alternative version exposes the magnetic tape to a non-uniform field as the tape approaches the electromagnets, and a uniform field as the tape is withdrawn. The speed at which the magnetic tape reel is transported away from the electromagnets is controlled so as to ensure adequate, but noise-free erasure. An improved tape height sensor is provided which serves to prevent damage to the magnetic tape reel from contact with the electromagnets, and further serves to detect when the magnetic tape reel is pulled out of place by the electromagnets.
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