Brother P-touch QL-1050 Service Manual page 23

(2) Media position detect sensor circuit
When performing printing and FEED motion through the process described in
subsection 2.3.4 (2) "Media feed motor driver circuit", the CPU reads the sensor value
to detect the medium position.
The CPU receives the voltage of the media position detect sensor (reflection type photo
sensor) sent through CN11 and input it through SENTAN (80 pin).
The CPU processes this voltage through AD conversion and inspects the print mark on
the back face of media that stays on the sensor position.
Fig. 2.3-6 Media Position Detect Sensor Circuit
(3) Cover open sensor circuit
QL-1050 has the cover open sensor. It identifies open/close of the top cover ASSY
from the status of mechanical switch.
Opening the top cover ASSY, the contact of cover open sensor on SB PCB opens.
The change of status is sent as the signal through CN15 to COVER (34 pin) of the
CPU.
The CPU detects open/close of the cover from the change of voltage at 19 pin.
The CPU stops all performances if detecting cover open during printing, FEED or CUT.
Fig. 2.3-7 Cover Open Sensor Circuit
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