Detectors - Star Micronics TSP400 Series Technical Manual

THEORY OF OPERATION

3-3. Detectors

(1) Paper-Out Detector
The paper-out detector is located at the paper entry slit. The detector consists of a reflective photosensor. The
photosensor's phototransistor remains ON while paper is present. It goes OFF when paper runs out, generating
output of a paper-out signal.
(2) Black-Mark Detector
This detector senses black marks indicating print start positions. The detector is useful only with specially marked
paper. Like the paper-out detector, the black-mark detector consists of a reflective photosensor. The photosensor's
phototransistor goes OFF when a black mark appears.
GND
+5V
Detection signal
Fig. 2-15 Paper-Out Detector
(3) Label Detector
The transmissive detector is used to detect print-start positions for labels. It operates by detecting the difference
in light transmission between backing-only and backing-plus-label portions of the paper.
5V
Detection signal
GND
R
R
(Reflective photosensor)
Light
Quantity of
transmitted light
Fig. 2-18 Label Detector
Paper
GND
+5V
Detection signal
Fig. 2-16 Black-Mark Detector
Light
Quantity of
transmitted light
Fig. 2-17
– 30 –
R
R
(Reflective photosensor)
Label paper
Backing paper
Paper
Paper
Black mark