Star Micronics TSP400 Series Technical Manual page 35

THEORY OF OPERATION
(4) Head-Up Detector
This detector consists of a leaf switch indicating whether the head is closed (in contact with the platen) or open
(separated from the platen). The leaf switch is closed when the head is closed; it opens when the head is opened.
+5V
R
Detection signal
Leaf switch
GND
Fig. 2-19 Head-Up Detector
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