Digital tape erasure conditioning system

Abstract

The following specification sets forth a digital tape erasure conditioning circuit and system in combination with a tape drive. The tape drive is such that it drives a magnetic digital tape across an erasing and recording head within a streaming cartridge tape drive. Information is written onto the tape and subsequently read and checked in a continuous streaming manner to assure the correctness thereof. The tape is driven with respect to its various channels over write and read head portions of the head and returned in the opposite direction for writing and reading on another channel. In order to provide for multiple channels, the head is moved laterally across the face of the tape and when moved, is provided with an air cushion between the tape and the head to prevent laceration and attendant damage to the tape surface. When the tape is to be erased, an AC erasure takes place as opposed to a DC erasure wherein the media is saturated at only one level as it passes the field of the erase head. The AC erasure is provided by a rapidly alternating field as the tape moves across the head. Thus, the media is subjected to a slowly diminishing cyclic field as it moves away from the erasure gap. This causes the magnetic intensity to diminish and leave a minimal amount of magnetization, due to the AC erasure. The erasing circuitry of this invention provides a 3.58 MHz square wave to two erase drive transistors. The inductance of the erase head in parallel with stray capacitance and a resonating capacitor, allows for a resonant circuit to pump the erase head until self limiting occurs, thereby provided an AC erasure to the previously magnetized tape.