Browse Prior Art Database

Print Hammer Actuation and Checking

IP.com Disclosure Number: IPCOM000088274D
Original Publication Date: 1977-May-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

de Vries, H: AUTHOR [+2]

Abstract

For driving as well as detenting the print hammer of a document inscriber, an E-core electromagnet has been used in which the middle leg pointed to the pivot point of the hammer (U. S. Patent 3,705,370). One outer leg of the core carried a winding to be energized by a current pulse and vigorously attracted an extension of the hammer whereby the latter is fired. The third leg was provided with a permanent magnet to catch and detent the hammer upon rebound after printing impact.

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Print Hammer Actuation and Checking

For driving as well as detenting the print hammer of a document inscriber, an E-core electromagnet has been used in which the middle leg pointed to the pivot point of the hammer (U. S. Patent 3,705,370). One outer leg of the core carried a winding to be energized by a current pulse and vigorously attracted an extension of the hammer whereby the latter is fired. The third leg was provided with a permanent magnet to catch and detent the hammer upon rebound after printing impact.

A simpler embodiment (shown above) comprises a U-core magnet, corresponding to the middle and lower legs of the previous E-core, for firing the hammer. The detenting leg of the E-core is replaced by a separate electromagnet either with a straight bar core, as shown, or with a U-core. This physical separation of the detent magnet from the firing magnetic circuit prevents magnetic shorting of either circuit and allows easier adjustment of the device.

An optical detector uses the passage of a light ray through a hole in the hammer as a check on proper firing and as an indication that the firing current, after a short delay, must be dropped. Restoration of the light is, in turn, an indication of sufficient rebound of the hammer to energize the detenting magnet.

Hard rubber inlays in the pole piece of the detenting magnet serve to cushion rebound impact and absorb the energy of the hammer.

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