US4992624A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic shield for visual display terminals
Assignee: HP Inc
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Filing: 1989-06-12
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Granted: 1991-02-12
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Expires: 2009-06-12
Abstract
Abstract A magnetic shield is designed to be retrofitted over a flyback transformer of a cathode ray tube display terminal. The magnetic shield consists of a layer of metal conductor, for example mu metal, and a layer of insulation, for example polyester film. The layer of insulation is placed upon the layer of metal conductor and the layers are rolled to form a spiral having greater than two windings. Tape may be used to secure the shape of the spiral. Additionally foam rubber pads may be attached to the inside of the spiral to provide a secure mechanical mounting to the flyback transformer and to provide air spacing as additional insulation against corona discharge. Also shrink tubing may be placed over the spiral to provide additional support to the spiral shape and to provide heat and electrical insulation.
Inventors
- 👤 Brian L. Benson
- 👤 Carl R. Haynie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 06:11
CPC Classifications
H; H01; H01F; H01F27/00; H01F27/34; H01F27/36; H01F27/366
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
93 words
A magnetic shield for being placed over a flyback transformer of a cathode ray tube display terminal and for reducing magnetic pulse and field emissions from the flyback transformer, the magnetic shield comprising: a sheet of metal conductor; and, a sheet of insulation, the sheet of insulation being placed upon the sheet of metal conductor and the sheets rolled to form a spiral having greater than two windings the spiral having a ductile springiness; attachment means for holding the sheet of insulation and the sheet of metal conductor in a rolled spiral shape.
Claim 2
Dependent Claim
93 words
A magnetic shield for being placed over a flyback transformer of a cathode ray tube display terminal and for reducing magnetic pulse and field emissions from the flyback transformer, the magnetic shield comprising: a sheet of metal conductor; and, a sheet of insulation, the sheet of insulation being placed upon the sheet of metal conductor and the sheets rolled to form a spiral having greater than two windings the spiral having a ductile springiness; attachment means for holding the sheet of insulation and the sheet of metal conductor in a rolled spiral shape.
Claim 3
Dependent Claim
24 words
A magnetic shield as in claim 1 wherein the sheet of metal conductor comprises mu metal and the sheet of insulation comprises polyester film.
Claim 4
Dependent Claim
13 words
A magnetic shield as in claim 1 wherein the attachment means comprises tape.
Claim 5
Dependent Claim
14 words
A magnetic shield as in claim 1 wherein the attachment means comprises shrink tubing.
Claim 6
Dependent Claim
35 words
A magnetic shield as in claim 1 additionally comprising foam rubber strips attached to the sheet of insulation at the inside of the rolled spiral shape and serving to provide contact with the flyback transformer.
Claim 7
Dependent Claim
92 words
A magnetic shield for being retrofitted over a flyback transformer of a cathode ray tube display terminal and for reducing magnetic field and pulse emissions from the flyback transformer comprising: a sheet of metal conductor; a sheet of insulation; and, attachment means for holding the sheet of insulation and the sheet of metal conductor in a rolled spiral shape; wherein the sheet of insulation is placed upon the sheet of metal conductor and the sheets are rolled to form a spiral having greater than two windings, the spiral having a ductile springiness.
Claim 8
Dependent Claim
92 words
A magnetic shield for being retrofitted over a flyback transformer of a cathode ray tube display terminal and for reducing magnetic field and pulse emissions from the flyback transformer comprising: a sheet of metal conductor; a sheet of insulation; and, attachment means for holding the sheet of insulation and the sheet of metal conductor in a rolled spiral shape; wherein the sheet of insulation is placed upon the sheet of metal conductor and the sheets are rolled to form a spiral having greater than two windings, the spiral having a ductile springiness.
Claim 9
Dependent Claim
24 words
A magnetic shield as in claim 6 wherein the sheet of metal conductor comprises mu metal and the sheet of insulation comprises polyester film.
Claim 10
Independent Claim
74 words
A method for reducing magnetic pulse and fields emissions from a flyback transformer of a cathode ray tube terminal, the method comprising the steps of: (a) rolling a conductive metal sheet and an insulator sheet together to form a spiral shield with greater than two windings, the spiral shield having a ductile springiness. (b) Attaching insulating pads to the inside of the spiral shield; and, (c) placing the spiral shield over the flyback transformer.
Claim 11
Independent Claim
74 words
A method for reducing magnetic pulse and fields emissions from a flyback transformer of a cathode ray tube terminal, the method comprising the steps of: (a) rolling a conductive metal sheet and an insulator sheet together to form a spiral shield with greater than two windings, the spiral shield having a ductile springiness. (b) Attaching insulating pads to the inside of the spiral shield; and, (c) placing the spiral shield over the flyback transformer.
Claim 12
Dependent Claim
23 words
A method as in claim 8 wherein step (a) includes taping the rolled conductive metal sheet to prevent the spiral shield from unwinding.
Claim 13
Dependent Claim
18 words
A method as in claim 8 wherein before step (c) shrink tubing is placed over the spiral shield.
Claim 14
Dependent Claim
25 words
A method as in claim 8 wherein the conductive metal sheet is comprised of mu metal and the insulator sheet is comprised of polyester film.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-11 | 1994-08-13 | 1995-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-11 | 1998-08-13 | 1999-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-11 | 2002-08-13 | 2003-02-12 | $7700.00 | Window Closed / Lapsed |