Seiko LTP1245R-C384-E, Техническое описание, Страница: 41 / 74

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3.7 HEAD-UP/PAPER DETECTOR
LTP1245 has a built-in head-up detector to detect whether the head is up or down and a paper detector to
detect whether paper is present or exhausted.
Both detectors are reflection photo interruptors which are designed to output signals as shown in
Table
3-11 according to their status.
The external circuit should be designed so that it detects output from the head-up and paper detector and
does not activate the thermal head when the head is in the up position and paper is exhausted. If the
thermal head is activated in the head up position, the thermal head may be damaged or the life of the head
may be shortened significantly. If the thermal head is activated in an out-of paper mode, the thermal head
and platen roller may be damaged.
Table 3-11 Detector’s Status and Output Signals
Detector Status Output signal
Head down “Low”
Head up detector
Head up “High”
Paper exist “Low”
Paper detector
No paper “High”
* Sensing by the head up detector is delayed from the actual completion of the
head up/down action.
3.7.1 General Specifications
Table 3-12 Absolute Maximum Ratings of Detectors
(at 25
°
C)
Item Symbol Rating
Forward current I
F
30 mA
Peak forward current I
FM
0.4 A
LED (input)
Reverse voltage V
R
5 V
Collector-to-emitter
voltage V
CEO
30 V
Emitter-to-collector
voltage V
ECO
5 V
Collector current I
C
20 mA
Phototransistor
(output)
Collector loss P
C
50 mW
Operating temperature T
opr
-25
°
C to + 85
°
C
Storage temperature T
stg
-40
°
C to + 100
°
C