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Magnetic Imaging System for Magnetic Printing

IP.com Disclosure Number: IPCOM000042127D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 3 page(s) / 60K

Publishing Venue

IBM

Related People

Kahwaty, VN: AUTHOR

Abstract

Conventional magnetic tape can be used as a magnetic imaging medium for magnetic printing as well as direct recording of the image where a small magnetized spot produces a pel (picture element) [1]. Alternatively, an image can be formed by erasure of a background pattern; this technique is common in the electrophotographic art where the imaging surface is a charged photoconductor and an image is formed by discharging the background with a controlled light source, such as a laser. In the magnetic printing case where a continuous series of flux reversals is necessary to provide an imaging force for magnetic toner, this requirement can be satisfied by recording an NRZ pattern in the magnetic tape imaging medium.

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Magnetic Imaging System for Magnetic Printing

Conventional magnetic tape can be used as a magnetic imaging medium for magnetic printing as well as direct recording of the image where a small magnetized spot produces a pel (picture element) [1]. Alternatively, an image can be formed by erasure of a background pattern; this technique is common in the electrophotographic art where the imaging surface is a charged photoconductor and an image is formed by discharging the background with a controlled light source, such as a laser. In the magnetic printing case where a continuous series of flux reversals is necessary to provide an imaging force for magnetic toner, this requirement can be satisfied by recording an NRZ pattern in the magnetic tape imaging medium. The wavelength of the NRZ pattern has only a few toner diameters to achieve full toner coverage, depending on toner chaining characteristics and tape oxide magnetic properties [2]. Images are then formed by selective erasure of this pattern with the use of a multiplexed imaging head, such as that described in [1]. Referring to Fig. 1, a schematic description of the imaging process is shown which utilizes this magnetic imaging system. A simple permanent magnet 1 is used in conjunction with a scraper blade 2 to remove residual toner from the moving magnetic tape imaging surface 3. A background NRZ pattern is front surface recorded with the use of a narrow gap longitudinal recording head 4 which spans the width of the magnetic imaging surface 3. This type of recording is well known in the digital magnetic recording art. A multiplexed transverse magnetic imaging head 5 is then used to erase the NRZ pattern in the background areas 6, thereby forming a magnetic latent image 7 by background erasure. A problem with high erasure field requirements is solved with the use of a special dual-layer magnetic oxide tape coating. Referring to Fig. 2, the magnetic oxide coating is formed with two different layers of active tape oxide; the top oxide layer 8 is longitudinally oriented, and the bottom oxide layer 9...