Mechanical Operation; Printhead Mechanism; Head Gap Adjusting - OKIDATA Pacemark 3410 Service Handbook

2.2

MECHANICAL OPERATION

2.2.01

Printhead Mechanism

The printer uses a highly efficient stored energy type printhead. Power is not consumed until the
printwires are activated, thereby extending the printhead life to approximately 200 million
characters.
The printhead uses 9 printwires in two columns. Each wire is welded to an armature. Behind
this armature is a spacer ring.
Each of the 9 printwire armatures has a permanent magnet behind it. The magnets attract the
armatures, pulling the printwires into the wire guide, thus keeping the wires inside the printhead.
A coil is wrapped around each of the permanent magnets.
When a dot is to be printed, current is passed through the appropriate coil. This creates an
electromagnetic field which counters the magnetic field of the permanent magnet. The armature
can then spring forward and the print wire (which is attached to the armature) strikes the ribbon
and imprints a dot on the paper.
When current is removed from the coil, the magnetic field of the permanent magnet attracts the
armature, causing the printwire to retract into the wire guide once again.
The printhead consists of the parts listed below.
Wire Guide
Print Wires
Armature Assembly
Spacer
Permanent Magnet Assembly
Thermistor: used to monitor the printhead temperature
Printed Circuit board with Coils

Head Gap Adjusting

The head gap adjusting mechanism modifies the gap between the platen and printhead. This is
accomplished by moving the adjusting lever on the right side of the printer mechanism. When
the lever is moved, the carriage shaft rotates. Since the carriage shaft is attached to the printer
mechanism through eccentric collars, turning the carriage shaft, changes the distance between
the platen and the printhead.
Principles of Operation 2 - 12 Pacemark 3410