Browse Prior Art Database

Hammer Flight Time Transducer and Measurement

IP.com Disclosure Number: IPCOM000051556D
Original Publication Date: 1981-Feb-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Baumberger, J: AUTHOR

Abstract

Print hammer 10 is driven by hammer actuator 11 to rotate on pivot 12 against the bias spring 13, thereby impacting paper 14 and ribbon 15 against type 16 moving in front of platen 17. Energy-absorbing pad 18 attached to the stationary bar 19 engages upper extension 20 of the print hammer to control the energy level of hammer 10 in accordance with the thickness of forms 14 and ribbon 15. Flight time transducer 21, which is located directly above extension 20, comprises a permanent magnet 22 connected to a pole piece 23 on which is wound a detection coil 24.

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Hammer Flight Time Transducer and Measurement

Print hammer 10 is driven by hammer actuator 11 to rotate on pivot 12 against the bias spring 13, thereby impacting paper 14 and ribbon 15 against type 16 moving in front of platen 17. Energy-absorbing pad 18 attached to the stationary bar 19 engages upper extension 20 of the print hammer to control the energy level of hammer 10 in accordance with the thickness of forms 14 and ribbon 15. Flight time transducer 21, which is located directly above extension 20, comprises a permanent magnet 22 connected to a pole piece 23 on which is wound a detection coil 24.

In operation, a signal is generated in detection coil 24 which is proportional to the hammer position, velocity and transducer/hammer gap. When the transducer 21 is mounted accurately on the frame of the print hammer unit with respect to a nominal print line location and a peak signal is detected while the hammer is in free flight without engaging the pad 18, the flight time from hammer 10 turn-on to when the hammer reaches a point near print impact can be measured. This signal can be used to measure hammer performance, diagnose machine problems, and adjust hammer flight time.

Transducer 21 is mounted so as to be adjustable with respect to the hammer unit in the directions indicated by arrow 25, and is movable a small amount with respect to the hammer unit (on the order of 5 mils) between flight time measurements. The velocity of the hammer 10 can be found using th...