Degaussing technique
First Claim
Patent Images
1. A method of degaussing magnetic material comprising the steps of:
- applying a magnetic field to the magnetic material with a flux density of at least 1,000 gauss and at an angle between 20 degrees and 70 degrees; and
alternating the field at a frequency of at least ten hertz for a sufficient time so that the flux density of at least 1,000 gauss passes through each portion of the magnetic material having a signal recorded on it at the angle of between 20 degrees and 70 degrees for at least one and one-half cycles of the alternating field.
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Abstract
To degauss cassettes of magnetic tape, a magnetic field is applied to the magnetic material with a flux density of at least 1,000 gauss and at an angle between 20 degrees and 70 degrees from the horizontal of the magnetic tape for a time period of at least one second and the field is alternated at a frequency of at least ten hertz. The magnetic material may be rotated while it is in the field.
35 Citations
35 Claims
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1. A method of degaussing magnetic material comprising the steps of:
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applying a magnetic field to the magnetic material with a flux density of at least 1,000 gauss and at an angle between 20 degrees and 70 degrees; and alternating the field at a frequency of at least ten hertz for a sufficient time so that the flux density of at least 1,000 gauss passes through each portion of the magnetic material having a signal recorded on it at the angle of between 20 degrees and 70 degrees for at least one and one-half cycles of the alternating field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. Apparatus for degaussing magnetic material comprising:
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means for applying a magnetic field to the magnetic material with a flux density of at least 1,000 gauss and at an angle between 20 degrees and 70 degrees with respect to the magnetic medium; and means for alternating the field at a frequency of at least ten hertz for a sufficient time so that the flux density of at least 1,000 gauss passes through each portion of magnetic material having a signal recorded on it at the angle of between 20 degrees and 70 degrees for at least one and one-half cycles of the alternating field. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of degaussing magnetic material comprising the steps of:
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applying a magnetic field to the magnetic material with a predetermined flux density and at an angle selected to reduce strength of a recorded signal on the magnetic material below a predetermined level; and alternating the field at a frequency of at least ten hertz for at least one and one-half cycles. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. Apparatus for degaussing magnetic material comprising:
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means for applying a magnetic field to the magnetic material with a predetermined flux density and at an angle selected to reduce strength of a recorded signal on the magnetic material below a predetermined level; and means for alternating the field at a frequency of at least ten hertz for at least one and one-half cycles. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35)
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Specification