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Browse Prior Art Database

Optically Sensitive Magnetic Head

IP.com Disclosure Number: IPCOM000044203D
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Schedewie, F: AUTHOR

Abstract

The high data density on modern magnetic disks necessitates that the magnetic head be accurately positioned. Optimum accuracy is obtained by positioning the servo tracks on the data disk rather than on a separate disk. The great problem with magnetically coded servo tracks in the vicinity of data tracks is crosstalk between the data signal channel and the servo signal channel. The two channels may be decoupled from each other by combining the magnetic coding of data with the optical or photonic coding of the servo tracks, using a photonic signal for controlling the head position. For this purpose, colored, dotted servo tracks are printed on top of the magnetic layer. Especially ink jets are used to print narrow tracks. By different periodical droplet sequences, the several tracks can be differently coded.

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Optically Sensitive Magnetic Head

The high data density on modern magnetic disks necessitates that the magnetic head be accurately positioned. Optimum accuracy is obtained by positioning the servo tracks on the data disk rather than on a separate disk. The great problem with magnetically coded servo tracks in the vicinity of data tracks is crosstalk between the data signal channel and the servo signal channel. The two channels may be decoupled from each other by combining the magnetic coding of data with the optical or photonic coding of the servo tracks, using a photonic signal for controlling the head position. For this purpose, colored, dotted servo tracks are printed on top of the magnetic layer. Especially ink jets are used to print narrow tracks. By different periodical droplet sequences, the several tracks can be differently coded. Thin-film technology, which is used for the production of the magnetic head structure (Fig. 1), can also be used to produce the servo track sensor structure (Fig. 2). According to the servo track signal, the sensor is an optical waveguide structure which is obtained by integrated optical circuit technology. The light wave is channelled in dielectric material of a first refractive index, which is surrounded by dielectric material of a lower, second refractive index to achieve total internal refraction. Basically, three dielectric films and one photolithographic step are required for generating a waveguide pattern. Assuming that t...