Electricity: electrical systems and devices – Control circuits for electromagnetic devices – Systems for magnetizing – demagnetizing – or controlling the...
Patent
1986-10-14
1988-06-14
Hix, L. T.
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
Systems for magnetizing, demagnetizing, or controlling the...
H01F 1300, H01H 4700
Patent
active
047516089
ABSTRACT:
A bulk degausser for erasing a reel of high energy magnetic tape. The degausser includes a circuit for generating magnetic fields including a coil defining a window for passage of the reel of tape. The coil includes a first winding having relatively few turns and a second winding, inductively coupled to the first winding, having relatively many turns. The circuit also includes an ac power supply connected to the first winding and a dc power supply connected to the second winding. A resonance capacitor is interconnected with the second winding for substantially balancing the inductive reactance of the second winding at the frequency of the ac power supply. The circuit also includes an isolation relay, interconnecting the capacitor and the second winding with the dc power supply, for isolating the dc power supply when the first winding is energized by the ac power supply. Energization of the second winding by the dc power supply causes a tape in said window to undergo a dc magnetic field, and energization of the first winding by the ac power supply induces ac current in the second winding resulting in a reel in said window experiencing an ac magnetic field. A drive mechanism for translating and rotating the reel of high energy magnetic tape with respect to the coil, is also disclosed.
REFERENCES:
patent: 3023280 (1962-02-01), Tronslin et al.
patent: 3938011 (1976-02-01), Littwin
"Taberaser 1500" Ad, Taber Manufacturing & Engineering Company.
"Taberaser 409" Ad, Taber Manufacturing & Engineering Company.
"KYBE/Weircliffe Bulk Tape Erasers/An Essential Part of Your Magnetic Tape Maintenance Program Ad, KYBE, Dennison KYBE Corporation.
Design and Construction of a Prototype Bulk Degausser (Draft Proposal), Prepared by IIT Research Institute, Mar. 1985.
"The Erasure of High Energy Tapes", by E. R. Burke and D. R. Sanders, IEEE Transactions on Magnetics, vol. MAG.-21, No. 5, Sep. 1985.
NSA/CSS Specification/Magnetic Tape Degausser, L14-4-A, Oct. 31, 1985.
The Garner 1200 & 1400 High-Energy Video Tape Erasers, Garner Industries, E-11-8-84.
Model 1400-Garner Professional Tape Degaussers Owner and Maintenance Manual, Unit 1400A, Ser. No. 851400A016, Garner Industries.
"Erasure of Signals on Magnetic Recording", William A. Manly, Jr., IEEE Transactions on Magnetics, vol. MAG-12, Nov. 1976.
Data Security, Inc.
Hix L. T,.
Porterfield David
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