Browse Prior Art Database

Regulating Actuator Driver

IP.com Disclosure Number: IPCOM000048296D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Holloway, JFL: AUTHOR [+2]

Abstract

The impact force and time of flight of the actuator used in a wire matrix printer is regulated by controlling the ampere-seconds applied to the actuator coil. The operation of the actuator is fully ballistic so any variation in energy applied to the actuator coil will show up as force variations at impact time.

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Regulating Actuator Driver

The impact force and time of flight of the actuator used in a wire matrix printer is regulated by controlling the ampere-seconds applied to the actuator coil. The operation of the actuator is fully ballistic so any variation in energy applied to the actuator coil will show up as force variations at impact time.

Fig. 1 illustrates the regulating actuator driver circuit. This varies from a standard actuator driver circuit by the addition of a current sense resistor, R1, voltage reference divider, R2 and R3, a comparator, LM339, a SR latch, 74279, and a voltage reference generator (not shown).

Fig. 2 is a timing diagram of the operation of the regulating actuator driver. The pedestal switch and the wire fire switch turn on at the same time. The pedestal time is used to increase the actuator current rapidly. The wire fire pulse sets the SR latch which turns on the wire fire switch, determines the minimum on time of the wire fire switch, and also determines the start of the reference voltage ramp. The voltage reference and the actuator current, sensed as a voltage across R1 in Fig. 1, are compared by the LM339 comparator. When the voltage reference equals the actuator current (voltage across R1), the SR latch is turned off, which turns off the actuator current.

Fig. 3 illustrates the regulating action of this actuator driver. The shaded area down the right side of the curve illustrates the ampere-seconds of energy added back by keeping the w...