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Exploitation of Moving Coil Actuator Ballistic Dynamics Through Relaxed Feedback Control to Enhance Impact Performance

IP.com Disclosure Number: IPCOM000061087D
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Sri-Jayantha, M: AUTHOR

Abstract

Relaxing the continuous feedback control of a moving coil print actuator permits a close control of hammer flight dynamics without overcontrol in response to transient phenomena, such as paper variations and vibration. The impact force and flight time variation of a moving coil print actuator can be effectively controlled by continuous feedback control. However, when the stroke length that is necessary to reach the paper/ ribbon interface changes randomly (as the interface material is fed over the platen surface), the resulting impact force can change significantly under continuous feedback control. Relaxing the controller temporarily suppresses the current to the moving coil.

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Exploitation of Moving Coil Actuator Ballistic Dynamics Through Relaxed Feedback Control to Enhance Impact Performance

Relaxing the continuous feedback control of a moving coil print actuator permits a close control of hammer flight dynamics without overcontrol in response to transient phenomena, such as paper variations and vibration. The impact force and flight time variation of a moving coil print actuator can be effectively controlled by continuous feedback control. However, when the stroke length that is necessary to reach the paper/ ribbon interface changes randomly (as the interface material is fed over the platen surface), the resulting impact force can change significantly under continuous feedback control. Relaxing the controller temporarily suppresses the current to the moving coil. After controlled acceleration (closed loop) to nominal print speed, the actuator is allowed to move as a ballistic mass, thereby reducing the impact force sensitivity significantly. This optimum sequencing of controlled and uncontrolled ballistic dynamics derives an actuator-driver configuration that needs only a hybrid signal detection circuit and no embedded impact sensor. Fig. 1 shows hardware 11-19 for closed loop feedback control, along with the auxiliary data acquisition and instrumentation elements 20-22. When a reference trajectory is chosen for a given stroke length, flight time, and impact force specification, the particular control would yield the optimum performance one can achieve. However, if the actual stroke length of a given printer hardware changes as a result of uncontrollable variables such as: 1). print head wear, 2). mechanical vibration,
3). paper/ribbon thickness variation, or 4). carriage rail tolerance, etc., the corresponding impact force can become significantly dependent on the reference stroke length. The sensitivity to stroke variation (effected by moving force sensor 18 in and out from nominal setting) varies as descri...