Printing And Ribbon Feed Mechanism - Citizen CLP-621 Technical Manual

2-1. Operation of Each Mechanism

2-1-4. Printing and Ribbon Feed Mechanism

The major components of the printing and ribbon feed mechanism are:
(a) Head SA
(b) Ribbon Motor F/R SA
(c) Ribbon gear train
Ink ribbon is set to the printer using the ribbon holders. Ribbon is supplied from the supply reel and
is taken up by the take-up reel with adequate ribbon tension, via the Ribbon Tension Shaft R/F SA.
The Ribbon Tension Shaft R/F SA is always pushed outward by the internal springs, and, when
ribbon slacks, it moves outward. When ribbon tightens, it moves inward. (Refer to the figures on
the later pages.)
The same tension sensor is installed on the take-up and supply sides. The tension sensor on the
take-up side is used to detect the position of the Ribbon Tension Shaft F SA, i.e. the ribbon tension
on the take-up side. While, the tension sensor on the supply side is used to detect the position of
the Ribbon Tension Shaft R SA, i.e. the ribbon tension on the supply side.
The tension sensor on the take-up side is also used to detect a ribbon running condition, and that
on the supply side is used to detect the ribbon end.
On the take-up side, the Ribbon Motor F turns to take up ribbon. On the supply side, the Ribbon
Motor R turns to supply ribbon, while applying adequate back tension to ribbon to eliminate ribbon
slack. On the supply side, the rotational direction of the Ribbon Motor R differs depending on the
ribbon winding type to be used. According to the ribbon winding type (inside-wound (ink-in) ribbon
or outside-wound (ink-out) ribbon), the Ribbon Winding Selection switch must be correctly set.
Printing:
When printing with ink ribbon, ink on the ribbon is melted by the heated thermal element of the
Head SA and is transferred on the media surface.
Taking up Ribbon:
Ribbon will be taken up on the take-up side as follows:
(1) As media is fed, ribbon is also fed by the friction force produced between media and the Head
SA.
(2) Ribbon slacks and the tension sensor on the take-up side turns OFF as the Ribbon Tension
Shaft F SA is pushed outward.
(3) The Ribbon Motor F starts to turn and ribbon is taken up.
(4) Ribbon tightens and the tension sensor on the take-up side turns ON. Then, the Ribbon Motor
F stops.
Supplying Ribbon:
On the supply side, the Ribbon Motor R turns to supply ribbon, while applying adequate back
tension. In the same way as on the take-up side, the tension sensor on the supply side detects the
ribbon tension to keep the ribbon tension constant. However, when printing is made and ribbon is
fed, the tension sensor on the supply side turns ON since ribbon is tightened at this time.
CLP-621 & CLP-631
(d) Ribbon Tension Shaft F/R SA
(e) Tension Sensor SA (Front/Rear)
2-10