Browse Prior Art Database

Unidirectional Line Following Servo System

IP.com Disclosure Number: IPCOM000091966D
Original Publication Date: 1968-Jul-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Patel, AM: AUTHOR

Abstract

In optical readout systems, it is often necessary to provide an electron beam scanning system capable of tracking a line of data on a recording medium in the presence of linear and angular positioning errors and disturbances such as vibrations or other perturbations. This system accomplishes line tracking with a unidirectional closed-loop track-seeking servo arrangement.

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Unidirectional Line Following Servo System

In optical readout systems, it is often necessary to provide an electron beam scanning system capable of tracking a line of data on a recording medium in the presence of linear and angular positioning errors and disturbances such as vibrations or other perturbations. This system accomplishes line tracking with a unidirectional closed-loop track-seeking servo arrangement.

The servo arrangement receives a read signal from vidicon 1 proportional in amplitude to the position of the beam relative to the center of the to-be-followed track. The graph shows the variation in amplitude of this signal as the beam moves transversely of the track. As shown at A, the maximum signal is received at the track center and a minimum signal B is received at either track edge. This read signal is supplied to error sensing network 2. Here it is processed to obtain a unidirectional signal whose amplitude is directly proportional to the proximity of the beam to the track center. This signal is compared at 3 with a reference signal from source 4, set to represent the track center amplitude. The difference is fed back to vidicon deflection network 5 via integrator network 6. The feedback signal always drives the beam in the same direction transversely of the scanning direction. Integrator network 6 produces a signal during each scan that allows correction of the ramp type of error due to angular displacement of the track with the normal scan path....