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@ Paper feed gear train
This gear train mnsists of a PF slip gear, which is coupled by
friction to the drive gear, a PF drive gear BK, which is coupled
via a clutch to the drive gear, a clutch gear BK, a PF reduction
gear, and a PF shaft gear, to transmit power to the PF shaft.
Drive gear
PF shaft gear
\
PF drive gear BK
/
/
PF
SI
\
PF ~eduction gear
Clutch gear BK
@ Ribbon feed gear train
The gear train consists of a ribbon slip gear, which is coupled
by friction to the drive pulley, a ribbon reduction gear, and a
ribbon drive gear, and works to continuously take up the ribbon
as the motor rotates.
Drive pulley \n
~
Ribbon reduction gear
@ Ribbon reset gear train
me gear train consists of a reset cam drive gear, which is
driven by the drive gear, and a ribbon reset cam. The ribbon
cassette in the red printing position is returned to the black
printing position by the rotation of the ribbon reset cam.
Drive gear
(2)
Ribbon
/
Reset cam 'drive gear
Sensor mechanism block
reset cam
The sensor mechanism block consists of three sensors, i.e. a
DP (dot pulse) sensor, a HP (home position) sensor, and an RP
(reset pulse) sensor, and plays an important role in the operation
and control of printer mechanism parts.
Carriage
RP sensor
DP disk
BK
otor BK
nterrupter)
ER+4RP
@
DP (dot pulse) sensor and HP (home position) sensor
The DP/HP sensor block consists of a dot pulse disk directly
coupled to the motor shaft and having equispaced apart 20
slits, a DP disk integrally fomed with a home position sensor
pulse disk having one slit, and photointerrupters solder
bound to the connector PCB SA and corresponding to the
respective disks. A pulse is generated as each slit of the disk
passes the sensor.
The dot pulse sensor outputs a signal (DP) which is used to
control the print solenoid, paper feed, and mlor change. On
@
the other hand, the home position sensor issues a signal
(HP) for every 17 DPs (or 20 DPs), and the signal (HP) is
combined with the signal (RP) output from the reset pulse
sensor hereinafter described to determine the DP munt stafi
position. No waveform shaping circuit is included in the
printer, therefore, it is requested that the shaping circuit be
provided at the user side.
RP (reset pulse) sensor
The sensor block consists of an RP switch SA which uses a
mechanical leaf switch attached on the bottom of the bottom
plate BK. As the carriage passes the switch, the actuator is
turned on and off to output a signal (RP). The signal RP is
used as the home position reference signal.
(3)
Head feed mechanism block
The head feed mechanism block consists of the pulley drive
gear, which is driven via the drive gear train, the drive pulley, the
timing belt SA (comprising a timing belt and a carriage drive pin),
the carriage, and the idle pulley. The carriage drive pin consists
of belt fixes A/B and carriage drive pipes U and L, and is fixed to
the timing belt. When the motor is rotated by a print or paper
feed command, the timing belt SA runs in the clockwise direction
to horizontally move the carriage with the carriage drive pipe
inserted in the elongated groove of the carriage.
When the printing operation is completed, power is shut off to
the motor at a prescribed timing to stop the carriage. At this
time, the head stops at approximately the center position.
It
f ix A
Tming
rriage drive pipe L
Tming belt SA
(4)
Printhead mechanism block
The printhead mechanism consists of a nose assembly housing
nine wires, a solenoid base comprising solenoids and armatures
for driving the wires, and a cover for keeping the armature
stroke to a prescribed value.
When the selected solenoid is energized for about 450ms in
synchronism with the dot pulse, the corresponding armature is
pulled into the solenoid. The armature action is transmitted to
the corresponding wire, causing the wire to strike the recording
paper through the ribbon to produce a dot on it.
HP sensor (photointerrupter)
-15-
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