Ribbon Advance Mechanism - Epson FX-870 Service Manual

Principles of Operation

Ribbon Advance Mechanism

The ribbon is held between the ribbon advance roller (ribbon driving gear) and the ribbon pressure
roller. When the carriage moves on the shaft, the timing belt turns the belt driven pulley, and the
torque is transmitted to the ribbon driving gear through the gear train. The ribbon driving gear
rotates counterclockwise no matter what direction the carriage moves, because the planetary gear
is used in the gear linkage.
Direction of Carriage Movement
Left to right
(indicated bv the black arrow)
Right to left
(indicated by the white arrow)
The ribbon brake spring, attached to the exit slot of the cartridge case, prevents slack in the ribbon
and keeps the ribbon tension at an appropriate level. The ribbon mask prevents the ribbon from
brushing against the paper.
Ribbon Advance Roller,
Ribbon Pressure
Gear (21,
Ribbon
Driving Gear
6-18
Table 6-2. Ribbon Advance Gear Linkage
Belt-driven pulley 3 Gear 1 + Gear 2 3
Ribbon-driving gear
Belt-driven pulley ti Gear 1 c3 Gear 3 @
G e a r 4 C=,
Figure 6-21. Ribbon Advance Mechanism
Gear Linkage
Ribbon-driving gear
Ink Ribbon
I'
Mask
Epson FX-870/1170