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3-31
3.6 OUT-OF-PAPER SENSOR
The printer has a built-in out-of-paper sensor (reflection type photo interrupter) to detect whether paper is
present or not. An external control circuit should be designed so that it detects output from the out-of-paper
sensor and does not activate the thermal head and motor when there is no paper. Doing not so may cause
damage to the thermal head or platen roller or shorten the life of the thermal head significantly. If the motor
is driven when there is no paper, a load is put on the paper drive system and the life of the printer may be
shortened significantly.
Table 3-16 shows about the out-of-paper sensor used for this printer.
Table 3-16 Out-of-paper Sensor
Item Specification
Type
NJL5902R (Rank B)
Manufacturer
New Japan Radio Co.,Ltd.
Figure 3-11 shows sample external control circuit of the out-of-paper sensor.
* The PS signal is “High” when there is no paper.
Figure 3-11 Sample External Circuit of the Out-of-paper Sensor
PS
Vps
GND
GND
Vdd
Vdd
Out-of-paper sensor
V
dd
V
dd
36k
Ω
at V
dd
=3.3V or
51k
Ω
at V
dd
=5.0V
300
Ω
at V
dd
=3.3V or
560
Ω
at V
dd
=5.0V
74HC14
CPU
470pF
GND
PS
V
PS
GND