Epson LQ-2550 Technical Manual page 57

Platen Gap Adjustment Mechanism
Figure 2-8 shows the platen gap adjustment mectlanism and Table 2-6 lists its specifications. The . "
rotation of the PG motor is transmitted to the pG gear via the PG reduction gear. The position of the
PG gear is detected by the PG HP sensor (Refer to Figure 2-8(a).).
When the PG gear rotates, it drives carriage guide shaft B. Because carriage guide shaft B is attached
off-center, its rotation varies the printhead-platen gap (Refer to Figure 2-8(b).).
Table 2-6. Platen Gap Adjustment Mechanism Specifications
Motor
PG motor;
Refer to Table 2-7.
Table 2-7. PG Motor Specifications
Item
Description
T y p e Four-phase 48-poie
P M t y p e s t e p p e r
motor
Drive Voltage 3 5 VDC
Hold Voltage 5 VDC
C o i l R e s i s t a n c e I 1250hrns~ 7% ] 25°C, for
Driving
400 PPS
Frequency
Driving Method
C o n s t a n t v o l t a g e
drive
PG Reduction Gear
P G M o t o r P i n i o n G e a r
(a) PG Motor Gear Train
Platen
(b) Platen Gap Adjustment
Figure 2-8. Platen Gap Adjustment Mechanism
I
Driving method
transmission
0'70
one coil
2 - 2 p h a s e
excitation
PG HP Sensor
Flag
. .
& Q
\ ,
PG Gear
Carriage Guide Shaft B
, Printhead
Gap
Guide Shaft B
I
PG HP sensor
Refer to Table 2-8.
Table 2-8. PG HP
I t e m
Type
Drive Voltage
1
Sensor
Sensor Specifications
Description R e m a r k s 1
Photo-interrupter
5 VDC
I