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Reducing Electromagnetic Interference in a Printer

IP.com Disclosure Number: IPCOM000042856D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Brinkman, JC: AUTHOR [+4]

Abstract

This article presents design considerations for providing electromagnetic information protection in a printer by reducing electrical and magnetic radiation. The radiation reduction is accomplished entirely within the covers of a printer used in word processing or similar systems. Filters for input data provide attenuation of signals at the required frequencies. Inputs to the filters are shielded as are inputs to an AC line filter for providing reduction of signals on the line. An AC compensator is provided to regulate the load in the AC circuit to the print motor. Rise and fall times of solenoid drivers in the printer are increased, and a set of secondary solenoids is activated at desired times during the print operation.

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Reducing Electromagnetic Interference in a Printer

This article presents design considerations for providing electromagnetic information protection in a printer by reducing electrical and magnetic radiation. The radiation reduction is accomplished entirely within the covers of a printer used in word processing or similar systems. Filters for input data provide attenuation of signals at the required frequencies. Inputs to the filters are shielded as are inputs to an AC line filter for providing reduction of signals on the line. An AC compensator is provided to regulate the load in the AC circuit to the print motor. Rise and fall times of solenoid drivers in the printer are increased, and a set of secondary solenoids is activated at desired times during the print operation. The secondary solenoids are exactly like the print solenoids and are driven during times when the print solenoids are not. Failure of these solenoids to properly operate is indicated by printer malselection. Final shielding occurs by using a metallized paint inside the covers. A seal is provided between the cover portions to assure conductivity therebetween.

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