Browse Prior Art Database

Magnetic Shielding of CRT Display Viewing Screens

IP.com Disclosure Number: IPCOM000038010D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Sansom, A: AUTHOR

Abstract

Electrostatic and low-intensity alternating magnetic fields are normally present in front of a CRT VTD at the user's position. There is concern over the possibility that these may be to some extent harmful to the user.

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Magnetic Shielding of CRT Display Viewing Screens

Electrostatic and low-intensity alternating magnetic fields are normally present in front of a CRT VTD at the user's position. There is concern over the possibility that these may be to some extent harmful to the user.

Screening and confinement of both magnetic and electrostatic fields are easily accomplished anywhere around the display except in front of the viewing screen, provided the display covers are made of a suitable conducting ferro- magnetic material. Additionally, electrostatic fields at the user's location are readily avoided by having a grounded transparent conducting film on the CRT face.

Proposed methods of reducing the magnetic fields in front of a CRT display, e.g., cancellation by bucking coils or with close fitting shields for the deflection yoke, may still leave low-intensity fields present at typical viewing distances.

A woven wire mesh of a suitable magnetic alloy wire, adjacent to the tube face, is proposed as the final shield against such weak low-frequency magnetic fields. When grounded, it will also confine electrostatic fields in front of the display, and avoid the need for a transparent conducting film on the tube face. In addition, suitably colored, it will provide contrast enhancement and anti- reflection properties typically provided by the plastic mesh filters at present in use.

Anonymous.

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