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Moving Coil Print Head Actuator

IP.com Disclosure Number: IPCOM000052891D
Original Publication Date: 1981-Jul-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Wilson, JT: AUTHOR

Abstract

A moving coil actuator enables a print head to be moved to a varying operating position while held with a constant force.

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Moving Coil Print Head Actuator

A moving coil actuator enables a print head to be moved to a varying operating position while held with a constant force.

Referring to Figs. 1 and 2, print head carrier 1 with printing elements 2 is moved counterclockwise about pivot 3 by energizing coil 4 within the flux field of permanent magnets 5. Print elements 2 are to be held against paper 6 on platen 7 by a constant force; however, component and assembly tolerances, and wear cause the amount of rotation required of carrier 1 to vary. Lift-off of elements 2 occurs with current reversal in the coil, or by gravity if current terminates.

A constant force between print elements and paper over a range of carrier travel is attained by maintaining a magnetic field of uniform flux density during coil energization. Therefore, the pole face dimension of magnets 5 is greater in the direction of coil travel than the corresponding dimension of the adjacent coil faces. A constant current drive source is used to control the print element force.

The impact force of the print elements on the paper during engagement can be controlled by applying a reverse coil current TR momentarily during the forward motion of the carrier (Fig. 3). Varying reverse current timing, magnitude and duration permit accurate force control.

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