Browse Prior Art Database

Head Alignment

IP.com Disclosure Number: IPCOM000062692D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 3 page(s) / 75K

Publishing Venue

IBM

Related People

Herring, GS: AUTHOR [+3]

Abstract

A computer-controlled technique for aligning the heads of a diskette drive, utilizing a commercially available "cat's-eye" alignment diskette, is described. An electronic card conditions the diskette drive's readback signal, as the signal is generated by reading the spinning diskette. The signal is digitized, and the digitized values are supplied to a controlling computer for processing and presentation to the operator performing head alignment. This technique represents an improvement over the prior method of the operator observing the readback signal on an oscilloscope and visually determining the degree of head alignment.

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Head Alignment

A computer-controlled technique for aligning the heads of a diskette drive, utilizing a commercially available "cat's-eye" alignment diskette, is described. An electronic card conditions the diskette drive's readback signal, as the signal is generated by reading the spinning diskette. The signal is digitized, and the digitized values are supplied to a controlling computer for processing and presentation to the operator performing head alignment. This technique represents an improvement over the prior method of the operator observing the readback signal on an oscilloscope and visually determining the degree of head alignment. Previously, head alignment was accomplished by using an analog alignment diskette, having a pre-written "cat's-eye" track, and adjusting the head position, as determined by the shape of the "cat's- eye" pattern observed on an oscilloscope. The signal was taken from the drive's control card data channel after amplification and filtering.

(Image Omitted)

This was a manual procedure that required calibration of the oscilloscope for each and every drive being tested. The interpretation of the "cat's-eye" pattern was a source of operator fatigue due to the constantly flickering pattern on the oscilloscope. Fig. l shows a typical "cat's-eye" pattern that was observed. The head's position was determined by calculating the percentage of amplitude of the smaller lobe, "A", compared to the larger lobe, "B", for both heads (in the case of a double-sided diskette drive). % = (A/B) x 100% A typical engineering specification requires that the ratio be no less than a defined percentage for both heads, and that any alignment error relative to the two heads be split between them. The amplitudes of the two lobes are subject to operator interpretation error which is a disadvantage to this process. This improvement provides the hardware and software necessary to do the following: 1. Condition the head's readback signal such that the "cat's- eye" lobe peaks can be sampled

and digitally measured. 2. Automatically calculate and display the head alignment lobe ratios (A/B) for both heads in an

easily interpretable format for the operator to

adjust the heads in realtime. Referring to Fig. 2, the differentia...