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Magnetoresistive Sensing of Print Actuators

IP.com Disclosure Number: IPCOM000060306D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Mazzeo, NJ: AUTHOR

Abstract

Using two magnetic resistors (M-Rs) as sensors, in a temperature- and magnetic-disturbance compensated bridge, provides a robust feedback sensor for improving print actuator dynamics. Printer quality and speed are enhanced by feedback control on the hammer. In order to achieve this feedback, a method of sensing hammer location and velocity is required to determine the force at impact. The figure shows a small permanent magnet 1 attached to hammer 2. The M-R sensor 3 is held in a position that allows the magnet 1 to move over the M-R sensor 3 in a bridge 4 (R1-R2) which can adjust the DC level to zero. Two M-R sensors are used; M-R sensor 5 is mounted next to M-R 3. This makes the sensor track for temperature and also subtracts any external magnetic disturbances.

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Magnetoresistive Sensing of Print Actuators

Using two magnetic resistors (M-Rs) as sensors, in a temperature- and magnetic-disturbance compensated bridge, provides a robust feedback sensor for improving print actuator dynamics. Printer quality and speed are enhanced by feedback control on the hammer. In order to achieve this feedback, a method of sensing hammer location and velocity is required to determine the force at impact. The figure shows a small permanent magnet 1 attached to hammer 2. The M-R sensor 3 is held in a position that allows the magnet 1 to move over the M-R sensor 3 in a bridge 4 (R1-R2) which can adjust the DC level to zero. Two M-R sensors are used; M-R sensor 5 is mounted next to M-R 3. This makes the sensor track for temperature and also subtracts any external magnetic disturbances. The waveforms inset in the figure show the following: Force, the output Kistler cell 7; Position, the output of M-R sensor bridge 4; and Power, the current applied to drive coil 6. The M-R sensor signal is the basis for monitoring the velocity of the hammer, and for adjusting the coil current pulse to maintain proper print dynamics.

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