2-6
2.2.4 Paper Feed Mechanism
There are three types of paper feed operations, as listed
below. Each type of paper feed operation is performed by
one or more of the component mechanisms.
Table 2-2. Paper Feed Operation and Mechanisms
Used
Each of the paper feed operations and mechanisms listed
above are described in the following section. The following
other mechanisms are also described:
• Manual release
• Semi-autoloading
• Cutter
• Clamshell
■
Paper feed operations
Feeding the paper roll
When current is applied to the paper feed motor set and the
motor rotates, the motor gear, intermediate gear, interme-
diate drive gear, and intermediate gear B rotate in se-
quence, driving the J paper feed roller shaft set and thus
feeding the paper roll.
Note that when the paper roll is fed, no current is supplied
to the clutch mechanism (refer to
Paper roll clutch mecha-
nism later in this section) mounted on the J paper feed roller
shaft set, to the paper holder switching solenoid, or to the
platen switching solenoid.
■
Paper roll near-end detection mechanism
The near-end sensor consists of the near-end detection
lever and a microswitch, and is located on the right side of
the paper supply section in the main case. This sensor
detects the amount of paper left on the paper roll.
The tip of the near-end detection lever is always pressed
against the edge of the paper roll by a spring inside the
microswitch. Therefore, when there is a large amount of
paper remaining on the roll, the near-end detection lever is
pressed against the side of the paper roll as depicted by the
solid lines in Figure 2-17. This keeps the microswitch
turned on. When the amount of paper left on the roll
decreases below a predetermined level, the tip of the near-
end detection lever no longer presses against the side of
the roll and moves in the direction indicated by the arrow
into the hole in the center of the roll core. This turns the
microswitch off and generates a signal indicating that the
paper roll is near its end.
Figure 2-17. Paper Roll Near-end Sensor
■
Cover open detection mechanism
The cover open sensor detects the cover open/close state,
and is located on the right rear of the operation panel. This
sensor consists of an LED and a photo IC. The beam of
light is blocked by the shutter portion on the rear of the
cover when the cover is closed. The light passes through
when the cover is open, and the output level of the photo IC
changes. This change is used as the cover open detection
signal.
Figure 2-18. Cover Open Sensor Circuit Diagram
Paper Feed Operation
Feeding paper roll
Feeding slip paper
Feeding validation paper
Mechanisms Used
Paper roll clutch
Platen switching
Paper roll clutch
Paper holder switching
Platen switching
V holder lever switching
Mechanical form stopper
Paper roll clutch
Paper holder switching
Mechanical form stopper
Platen switching
V holder lever switching
CONFIDENTIAL
Summary of Contents for U375 - TM B/W Dot-matrix Printer
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