Label Gap/Black Mark Sensors - Intermec EasyCoder PC41 Service Manual

5.8 Label Gap/Black Mark Sensors

Description
Replacement
Intermec EasyCoder PC41—Service Manual
The receiver part of the label gap sensor and the black mark sensor are
fitted on the same circuit board. The purpose of the label gap/black mark
sensors is to control the printer's stepper motor to feed the media properly
in relation to the gaps between labels, detection slots, or black marks at the
back of the media. It also detects out-of-media conditions. The label gap/
black mark sensor PCB is fitted below a window in the floor of the media
cavity using two screws. It is connected to J3/J7 on the main board.
To allow the use of parallel labels fitted on the same liner, the sensors are
placed slightly to the right of the center-line (as seen from the front) as fol-
lows:
- Label Gap Sensor
- Black Mark Sensor
The board has one LED emitter and two receivers. The black mark sensor
emitter shines upwards. The black mark sensor receiver detects light
reflected by the back side of the media. No light received is interpreted as a
black mark.
The label gap sensor receiver detects light from the emitter board in the
print frame (see Chapter 4.7) that passes through gaps in the media or
through the liner between labels. No light received is interpreted as a label
(or similar) and light received is interpreted as a gap.
The sensitivity of the label gap/black mark sensor is adjusted automatically
when the printer is powered on, provided the user has set the printer to
black mark or label gap detection prior to this.
• Remove the main board from the base frame moulding.
• Disconnect the cables from J3 and J7 on the main board.
• Adjust media guides for maximum media width.
• Remove the screws that hold the sensor board.
• Install new board in reverse order.
4.5 mm 0.177 inches
10 mm 0.394 inches
Chapter 5—Base Frame
43