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Print Hammer Failure Detection

IP.com Disclosure Number: IPCOM000087394D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Kane, MH: AUTHOR [+2]

Abstract

The environment in which a print hammer operates normally contains ink particles and paper dust particles. Due to an accumulation of such particles, it is possible that the ballistic element in a ballistic-type hammer will stick after some period of operation. In a printer where a ballistic hammer is impacting a rotating print wheel, if the hammer does not retract quickly enough, the next pedal of the print wheel may strike the hammer, thereby damaging the print wheel or the hammer.

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Print Hammer Failure Detection

The environment in which a print hammer operates normally contains ink particles and paper dust particles. Due to an accumulation of such particles, it is possible that the ballistic element in a ballistic-type hammer will stick after some period of operation. In a printer where a ballistic hammer is impacting a rotating print wheel, if the hammer does not retract quickly enough, the next pedal of the print wheel may strike the hammer, thereby damaging the print wheel or the hammer.

The failure of the hammer to retract in a prescribed period of time can be detected by putting either a photocell detector which is activated by retraction of the ballistic element in the hammer, or by putting a magnetoresistive or hall cell detector on the ballistic element. The output from the detector, which indicates when the hammer is in the retracted position, can be electronically compared to the hammer firing signal. If the hammer is not in the retracted position in a prescribed amount of time after the hammer fire signal, it is an indication that the hammer is not operating satisfactorily.

When the default condition is detected, the system can be designed either to give the operator a visible indication or, alternatively, to include a pressurized lubricating mechanism which will pump lubricant to the hammer if it is not retracting in the prescribed period of time.

One example of the type of hanmer which could utilize this type of failure detecti...