Browse Prior Art Database

Logical Zero Position Indicator

IP.com Disclosure Number: IPCOM000086629D
Original Publication Date: 1976-Oct-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 40K

Publishing Venue

IBM

Related People

Janssen, DM: AUTHOR [+2]

Abstract

An arrangement is described in which control logic (e. g., microprocessor) uses counts from a tachometer positioned on the rotor of a rotating head device for turning the head on and off during operation of the device.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Logical Zero Position Indicator

An arrangement is described in which control logic (e. g., microprocessor) uses counts from a tachometer positioned on the rotor of a rotating head device for turning the head on and off during operation of the device.

In Volume 18, No. 3, August 1975, pp. 622-623, of the IBM Technical Disclosure Bulletin, there is described an arrangement for calibrating a signal recorder. Essentially, the method described there is directed to aligning the read gap relative to a recorded track on a length of recording media and the fiducial mark on the tachometer. The present article is concerned with locating a write and erase head with respect to the read head.

Fig. 1 depicts a conventional tape recorder with a tachometer having a fiducial mark and a rotor having erase, write, and read gaps. The recording media is helically wrapped about upper mandrel half 10 and lower mandrel half
12.

Fig. 2 depicts the length of magnetic media (in three sections, (A), (B) and
(C)) lying in a horizontal plane with the erase (E), write (W) and read (R) heads positioned in their respective positions along selected data tracks. The recording media includes servo sections positioned at leading edge 16 and trailing edge 18 and a data section positioned between the servo sections.

In order to locate the heads relative to one another and relative to the fiducial mark, hereinafter called zero position indicator (ZPI), all tachometer counts are taken from the ZPI mark. For normal operation, the heads travel in the direction shown by arrow 20. As is shown in section (A) the number of tachometer pulses are counted, beginning from the ZPI pulse until the...