3-29
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 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 3-12 shows sample external circuit of the out-of-paper sensor.
* The PS signal is “High” when there is no paper.
Figure 3-12 Sample External Circuit of the Out-of-paper Sensor
V
dd
V
dd
CPU
74HC14
470pF
GND
PS
V
ps1
GND
36kΩ at Vdd=3.3V or
51kΩ at Vdd=5.0V
300Ω at Vdd=3.3V or
560Ω at Vdd=5.0V
300Ω at Vdd=3.3V or
560Ω at Vdd=5.0V
V
ps2
V
dd
Out-of-Paper sensor
Printer main body
