3-30
3.7 PLATEN POSITION SENSOR
The printer has a built-in platen position sensor for detecting whether the platen block is set or released. This
sensor is a mechanical switch which is designed to be on when the platen block is set and to be off when it is
released.
The external circuit should be designed to detect output from the platen position sensor and output from the
out-of-paper sensor described in 3.8. If the platen open and the no paper are detected, the external circuit
should not activate the thermal head. Otherwise, the thermal head may become damaged or its life may be
shortened significantly.
Activate the thermal head when the platen block is closed by detecting the output from the platen position
detection, and in the paper presence state by detecting the output from the paper sensor.
3.7.1 General
Specifications
Table 3-17 shows about the general specification
Table 3-17 General Specifications of Platen Position Sensor
Item Specification
Rated voltage
DC5.0V
Rated current
1mA
Contact resistance
3
Ω
max.
Figure 3-13 shows sample external circuit of the platen position sensor.
Platen position sensor
GND
V
dd
47k
Ω
HS
GND
0.1
μ
F
300
Ω
CPU
Printer
* The HS signal is “High” when the platen is released.
Figure 3-13 Sample External Circuit of the Platen Position Sensor
3.7.2 Platen Position Sensor Precautions
•
Be sure that there is a time lag between the time when the thermal head is set and the time when
the platen position sensor actually starts detecting.
•
Always use the capacitor shown in Figure 3-13 to prevent the switch from malfunctioning due to
chattering.
