Browse Prior Art Database

Optical Recording of Servo Pattern on Magnetic Discs

IP.com Disclosure Number: IPCOM000044429D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Aviram, A: AUTHOR [+2]

Abstract

The introduction of an optical servo track onto magnetic discs offers an advantage over magnetic servo. This advantage stems from the non- interference of the optical track with the magnetic track and the resulting higher information density that it is possible to record magnetically. This disclosure proposes a high-gain, simple photographic method as a way of obtaining the optical pattern required. The free-radical photographic method proposed is very efficient and convenient to use. Its features are: low energy (10-20 ergs per square centimeter at 4400 A), dry working, development by red radiation, and fixing by controlled heat.

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Optical Recording of Servo Pattern on Magnetic Discs

The introduction of an optical servo track onto magnetic discs offers an advantage over magnetic servo. This advantage stems from the non- interference of the optical track with the magnetic track and the resulting higher information density that it is possible to record magnetically. This disclosure proposes a high-gain, simple photographic method as a way of obtaining the optical pattern required. The free-radical photographic method proposed is very efficient and convenient to use. Its features are: low energy (10-20 ergs per square centimeter at 4400 A), dry working, development by red radiation, and fixing by controlled heat. In addition, the method produces high contrast and high resolution images since the phenomenon involved is molecular rather than that of the crystalline state, as is the case with silver halide photography [*]. The photographic composition is sensitive to short wavelength light, yet transparent in the red. When this composition is exposed with blue light (4400 A), a chemical reaction occurs that produces a product which absorbs red light and at the same time acts as a sensitizer that transfers the energy absorbed (the red radiation) to affect the photochemical reaction that required blue light initially. Thus, the process is in effect a process with gain. Usually one images with blue light and develops with red light. Details of the process are given in [*]. The process described ther...