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Print Hammer

IP.com Disclosure Number: IPCOM000086861D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

McGuire, JE: AUTHOR

Abstract

A print hammer having a high retention force and relatively low uniform retracting force can be constructed by adding a flange to a hammer of magnetic material and translating the hammer within the core of an annular permanent magnet.

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Print Hammer

A print hammer having a high retention force and relatively low uniform retracting force can be constructed by adding a flange to a hammer of magnetic material and translating the hammer within the core of an annular permanent magnet.

Referring to the figure, hammer 1 of magnetic material has formed integrally therewith flange 2 and is driven in the direction of the arrow by a suitable actuator 3 with elastomeric pad 4. The rear portion of the hammer is encased in a molded polymer bearing 5 which extends beyond the end of the hammer to provide an impact surface for the actuator. An annular magnet 6 surrounds the rear hammer portion. The forward end of the hammer moves between a pair of resilient pads or stops 7 which limit forward travel of the hammer.

When the hammer is moved forward by actuator 3, the leading tip of the hammer engages type element 8 and flange 2 engages resilient stops 7. The trailing end of the hammer remains within magnet 6 and the flux field of the permanent magnet acts to retract the hammer with a relatively low uniform force. As the hammer moves toward the retracted position, flange 2 enters the field of the magnet to increase the retention force on the hammer and reset actuator 3. Magnet 6 is preferably coated with a thin nonmagnetic material 9 to prevent direct sealing of the flange with the magnet.

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