Service manual

2-10 Mechanism Configuration and Operating Principles Rev. B
Confidential
Paper detection mechanism
The paper detection mechanism is located in the paper path. The mechanism provides paper
end detection for the paper roll and semi-automatic loading by detecting presence or absence of
the paper roll when it is inserted. Since the paper detector switch sub assembly is a micro switch,
it is always ON when the paper roll is loaded.
Paper roll near-end detection mechanism (optional)
The near-end detector assembly consists of the near-end detector lever and a microswitch sensor
and is located on the right side of the lower case. This detector senses 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 the figure below. This keeps the microswitch turned on. When the amount of
paper left on the roll decreases below a predetermined amount, 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.
Auto-cutter mechanism
The printer executes a partial cut (one point left uncut) by driving the cutter motor.
When the motor is energized from the standby state, the wormwheel rotates in the direction
indicated by arrow A through the gears from the motor. The resulting motion of the wheel pin
through arm slot C causes the arm to move in direction B. This, in turn, causes slot D to move the
Figure 2-13 Paper roll near-end detection mechanism
Paper roll center
Lower case
Microswitch
Near-end
detection lever
Paper roll