Leibinger JET Rapid, Technical Information

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Information about encoders
Page 31 of 61
6 Information about encoders
Regarding the encoders that are used for a high speed application, there are two limitations to be
considered. The first one is the maximum output frequency of the encoder and the other one is the
maximum input frequency of the X1 encoder input interface of the printer.
6.1 Basics
Regarding speed measuring the JET Rapid printers work with internal speed as well as with an
external encoder.
An external encoder has the advantage that a varying production speed would not affect the quality of
the printout. Additionally the printer would recognize a stop of the production line.
Nevertheless, using an encoder for high speed printing requires a careful selection of the encoder.
6.2 The resolution and the output frequency of the encoder
The resolution of an encoder indicates the number of pulses per rotation.
An encoder, for instance, with a resolution of
2.500 indicates that the encoder provides 2.500 pulses
per rotation of the encoder axis.
Normally there is a measuring wheel with a circumference mounted on the axis of the encoder. The
given circumference of the measuring wheel and the resolution of the encoder results in the pulses per
mm.
𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛 𝑜𝑜𝑜𝑜 𝑝𝑝𝑛𝑛𝑝𝑝𝑝𝑝𝑛𝑛𝑝𝑝 𝑝𝑝𝑛𝑛𝑛𝑛 𝑛𝑛𝑜𝑜𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑜𝑜𝑛𝑛
𝐶𝐶𝑟𝑟𝑛𝑛𝐶𝐶𝑛𝑛𝑛𝑛𝑜𝑜𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝐶𝐶𝑛𝑛 𝑛𝑛𝑛𝑛𝑟𝑟𝑝𝑝𝑛𝑛𝑛𝑛𝑟𝑟𝑛𝑛𝑚𝑚 𝑤𝑤ℎ𝑛𝑛𝑛𝑛𝑝𝑝 [ 𝑛𝑛𝑛𝑛 ]
= 𝑝𝑝𝑛𝑛𝑝𝑝𝑝𝑝𝑛𝑛𝑝𝑝 / 𝑛𝑛𝑛𝑛
If, for instance, the circumference of the measuring wheel is 200 mm the resolution is:
2.500
200
𝑝𝑝𝑛𝑛𝑝𝑝𝑝𝑝𝑛𝑛𝑝𝑝
𝑛𝑛𝑛𝑛
= 12,5 𝑝𝑝𝑛𝑛𝑝𝑝𝑝𝑝𝑛𝑛𝑝𝑝 / 𝑛𝑛𝑛𝑛
In order to determine the output frequency of the encoder, which represents also the input frequency
at the X1 encoder interface of the printer, the resolution has to be multiplied with the actual production
speed.
𝐼𝐼𝑛𝑛𝑝𝑝𝑛𝑛𝑟𝑟 𝑜𝑜𝑛𝑛𝑛𝑛𝑓𝑓𝑛𝑛𝑛𝑛𝑛𝑛𝐶𝐶𝑓𝑓 𝑋𝑋 1 =
𝑝𝑝𝑛𝑛𝑝𝑝𝑝𝑝𝑛𝑛𝑝𝑝
𝑛𝑛𝑛𝑛
∗
𝑛𝑛𝑛𝑛
𝑛𝑛𝑟𝑟𝑛𝑛𝑛𝑛𝑟𝑟𝑛𝑛
If, for instance, the production speed is 1000 m/min

1.000.000 mm/min the input frequency is:
𝐼𝐼𝑛𝑛𝑝𝑝𝑛𝑛𝑟𝑟 𝑜𝑜𝑛𝑛𝑛𝑛𝑓𝑓𝑛𝑛𝑛𝑛𝑛𝑛𝐶𝐶𝑓𝑓 𝑋𝑋 1 =
12 , 5 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝
𝑚𝑚𝑚𝑚
∗
1 . 000 . 000 𝑚𝑚𝑚𝑚
𝑚𝑚𝑚𝑚𝑚𝑚𝑝𝑝𝑚𝑚𝑝𝑝
=
12 . 500 . 000 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝
𝑚𝑚𝑚𝑚𝑚𝑚𝑝𝑝𝑚𝑚𝑝𝑝
= 208.333,33
𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝
𝑝𝑝𝑝𝑝𝑠𝑠𝑠𝑠𝑚𝑚𝑠𝑠
= 208,33 𝑘𝑘𝑘𝑘𝑘𝑘
Important:
It is highly recommended thoroughly checking the technical specifications of the encoder that is used.
An encoder with a high resolution leads to high output frequencies at high speed operations.
Make sure that the encoder is able to manage such frequencies!
Output
frequency
of the
encoder
Input
frequency
of the
printer
=