Exploitation of Moving Coil Actuator Ballistic Dynamics Through Relaxed Feedback Control to Enhance Impact Performance
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
Publishing Venue
IBM
Related People
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.
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...