Hitachi IJ RX2 Technical Manual page 47

(5) When a rotary encoder is used, the print character width cannot be changed by changing the IJ printer character
width set value.
When the print character width must be changed, a device (timing belt, pulley, etc.) which varies the conveyer
speed and rotary encoder speed synch signal pulse frequency ratio must be installed.
(6) Restriction of the speed synchronization signal pulse frequency from the rotary encoder
OFF
Encoder signal
See that the duty is between 30% and 70%.
Arrange for encoder signal cycle time (t1) to be at least 5 μs.
Flat period of encoder signal (t3) : 2 μs min.
(7) Rotary encoder selection method and calculation method
The print character width when the product speed matching function is used is determined by the amount of
movement of the product per encoder pulse.
Several examples are introduced below.
Example 1: Calculate the resolution of the rotary encoder when the rotary encoder is connected directly to the
conveyer shaft.
Encoder
<Calculation conditions>
●Dot font
●Inter-character space
●Inter-character interval
●Diameter of conveyer pulley : 60mm
Distance the conveyer moves per 1 revolution of the rotary encoder
1
60mm
2
Number of scans which must be executed while the conveyer is moving 1mm
6 scans/1.8mm=3.33 scans/mm
3
Required resolution of the rotary encoder (number of output pulses per 1 revolution of
the rotary encoder)
188.4mm/rev
t1 5μs min.(f=200 kHz max)
t3 2 μs min.
ON
Conveyor
: 5
: 1 dot (1 scan)
: 1.8mm [horizontal direction 6 dots (6 scans)]
3.14=188.4mm/rev
×
3.33 scans/mm=628PPR ( 2500PPR, Division factor=4)
×
t2
ON
t2
Duty ＝
t1
Diameter
7 dots (horizontal direction 5, vertical direction 7)
×
(Inter-character dots 5 + inter-characters space 1)
.
=
.
×100％
●Input/output (I/O) specifications 4-16