Hitachi IJ RX2 Technical Manual page 42

(3) Print target detector signal noise filter
(a) IJ printer built-in noise filter setting.
This function uses to filter the normal noise generated at the print target detector signal and noise
generated by water drops, etc. with CR.
The target sensor filter function (See "Instruction manual 4.14 Set the print specifications") is effective
against sensor chattering.
Internal circuit diagram
SW1 setting
ON
1 2
(b) Addition of external noise filter
In case that the built-in noise filter cannot eliminate the noise, add the following additional CR filter outside
of IJ Printer.
If R1=1kohm (0.5W) and C1=1micro farad /25V, the CR time constant=1ms. If R1=1kohm (0.5W) and
C1=1micro farad /25V, the CR time constant=1ms. The filter could eliminate a several hundred micro-seconds
of noise. If you need to eliminate bigger noise, add an additional capacitor in parallel with C1.
Notes for addition of CR filter:
- R1 has to be less than 1kohm.
- C1 should be temperature compensating ceramic capacitor. If it is difficult to find such type of
capccitor, select high-precision and good temperature characteristics type of high dielectric
ceramic capacitor as much as possible.
- R1 and C1 should be placed near IJ Printer as much as possible.
4-11 ●Input/output (I/O) specifications
1kΩ
・SW1 "8" ON : Filter ON
OFF: Filter OFF
3 4 5 6 7 8
Tr
Print target detector
SW1-8
2.2μF
Time constantｔ＝2.2ms
ON
OFF
R1(Addition)
Power 1
Signal 2
GND 3
C1(Addition)
DC24V
SW1-5
IJ printer