Control of Print Hammer Flight Time
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
A print hammer is moved into engagement with a platen by applying a current for a selected period of time to a coil which surrounds the hammer. The current is turned off prior to the hammer striking the platen so that there is a free flight time of the hammer. The voltage, E, across the hammer coil is defined by the equation (Image Omitted) where L is the inductance in the coil, Le is the eddy current inductance, Ke is the back emf coefficient, x is the distance of travel of the hammer, i is the current in the coil, and R is the resistance of the coil. When the current in the coil is turned off, the first term of the equation goes to zero; this is indicated in Fig. 1. This is when the print hammer begins its free flight.