Browse Prior Art Database

Velocity and Displacement Servo

IP.com Disclosure Number: IPCOM000088202D
Original Publication Date: 1977-May-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Martin, VC: AUTHOR

Abstract

A system is shown for servoing both the displacement and velocity of a print drum.

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Velocity and Displacement Servo

A system is shown for servoing both the displacement and velocity of a print drum.

Once the print drum 10 has been accelerated to speed by power amplifier 11 and motor 12, as recognized by circuit 13, both the displacement and velocity are maintained through a digital phase-locked servo loop. A digital tach 14 supplies tach pulses to a counter 15 which supplies its sample pulses to sync circuit 16. The other input to circuit 16 is the clock signal derived from oscillator 17 and counter 18. The sync circuit thus derives periodic tach sample and tach reset pulses, supplying the tach sample pulses to register 19 and the tach reset pulses to counters 20 and 21.

Counter 20 references the displacement of the drum (tach) from the ideal (clock) position by counting the clock pulses versus reset pulses to give a digital phase comparison which is referenced by the tach sample pulses to give relative displacements when loaded into register 19. A similar digital phase comparison made by counter 21 is loaded into register 20 to indicate relative velocity. The resultant relative displacement (error) and relative velocity (error) are supplied to circuit 23 which responds thereto by supplying correction signals to power amplifier 24 for operating motor 12.

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