Principles Of Operation - Epson FX Series Product Support

EPSON PRINTERS
1.1 PRINCIPLES OF OPERATION
The descriptions of the printer mechanics is generic to all models with few
exceptions.
O
PRINTER MECHANISM
The printer mechanisms are dot matrix mechanisms with sub-miniature print
heads developed for high quality, precision printing. Because some the units
come with tractor feed attachments and also are equipped with rubber
plates, they maybe used with continuous business forms or rolledor cut sheet
paper, as required by the user. No special additional equipment need be
purchased to accommodate the various paper types. Basic operation of all
the models is essentially the same.
Sensor Mechanisms
Sensor mechanisms on all models include the home position (HP), print
^ timing (PTS), and the paper end (PE) sensors.
Home Position (HP) Sensor
The HP sensor assembly consists of a HP sensor and a sensor plate,
situated beneath the carriage assembly. The sensor emits a HIGH signal
whenever the sensor plate intercepts the optical axis of the photo
sensor. The variations in the signal alert the main CPU as to when the
carriage is in or out of the home position (i.e. the left end of the platen).
This signal serves as a reference signal for the printing operation.
^ Print Timing Sensor (PTS)
The PTS sensor mechanism consists of the sensor and a sensor disk,
located on the shaft of the carriage motor. The PTS signal is generated
in order to coordinate carriage speed with firing of the dot wires,
allowing adequate time for the print operation to be performed. A
HIGH signal isemitted as the slits in the disk pass the optical axis of the
photo sensor.
1-1
PRINCIPLES OF OPERATION
Paper End (PE) Sensor
The PE sensor consists of a reed switch mounted on the PE sensor board
and a reed magnet mounted on a PE sensor lever. The assembly is
attached at the rear of the printer mechanism. When the printer runs out
of paper, the reed magnet and reed switch meet causing the PE warning
signal to be output.
PRINT ASSEMBLY
The print assembly is comprised of the carriage assembly, including the
carriage motor, timing belt, and platen; ancf the print head, which is
mounted on the carriage assembly.
Carriage Assembly
The carriage assembly is moved back and forth along the carriage shafts
by the timing belt, which is driven by the carriage motor via the belt
driven pulley. (Figure 1-1)
Carnage
Carnage motor
Timing belt
Fig. 1-1. Carriage Mechanism