EBS Ink-Jet Systems EBS-6200, Руководство пользователя, Страница: 88 / 124

EBS-6200
Printer User's Manual
Chapter 4 - Operating the Printer
86
20091020#1.0
veyor starts moving at
the speed that is greater than declared, then the print will stretch proportionally.
● When a shaft-encoder is used:
Resolution
, which is given as a number of dots per centimetre
(the Resol. dot/cm parameter) and
encoder constant
, which is given as a number of pulses per
s
o
before the printing of the previous vertical row is completed, it must be ignored. Such a situation
s exceeded. And this occurs when greater spaces
],
where:
R
– actual resolution [dots/cm],
t
– time between successive vertical rows [µs/dot].
From the above, it appears that the maximum print rate for a given resolution,
R
, and the total time,
Ttot , which is needed to print a row, is defined as:
V
m a x
= l i m 6*10
5
*(R*t)
-1
[m/min].
t->Ttot
The value is the same irrespective of whether an internal generator or a shaft-encoder is used.
When the printer works with an internal generator, it is very easy to reach the maximum print rate
because printing is controlled by the printer’s computer which uses a common, very accurate, quartz
oscillator to generate ink drops and release printing of successive rows. Therefore the two processes
are absolutely synchronous and cophasal.
When the printer works with a shaft-encoder, it is much more difficult to reach the maximum print rate
because two asynchronous generators need to be used. The first one is a quartz oscillator and the
other is the shaft-encoder. In addition the pulses from the shaft-encoder are unstable and in no way
are they synchronous with the pulses generated by the oscillator.
The symptoms of speeding are also different:
● When an internal generator is used, successive rows are timed at the same time intervals.
A change in the conveyor speed results in a change of the distance between vertical rows and the
change is proportional to the change of the conveyor speed. If the maximum speed is exceeded
slightly, the effect is hardly visible.
● When a shaft-encoder is used, the symptoms of speeding depend on the versions of the software
that is installed on the printer. For version
20_0A
or later, each time the print rate is exceeded
rows of print are spaced widely, as it is the case when an internal generator is used.
4.6.5. Problems with Reaching Maximum Print Rate when Shaft-
encoder is Used
The description given below is a case study of the maximum
row (see points
1
,
2
above), then the printer indicates an error. If the con
metre (the Enc const p/m parameter). In this configuration the printer “does not know” when it i
likely t receive a row release pulse to start printing another vertical row. If the pulse is generated
occurs only when the maximum print rate i
between some rows appear.
The print rate is defined by the following formula:
V=6*10
5
*(R*t)
-1
[m/min
print rate. If the rates are smaller than
the maximum (with a tolerance specified below) no problems occur . The printers on which
software version
20_0A
or later is installed switch automatically to printing at the maximum (constant)
rate when this maximum rate is exceeded.
1. The encoder constant.
If the shaft-encoder constant is too small, it will be difficult to reach the set resolution - the real
resolution will be rather distant from the setting. The shaft-encoder constant,
S , is given as a number
of pulses generated when the conveyor travels over a distance of one metre. For a given resolution r
the printer sets the value of the system divider, D , which matches the two quantities with each other.
The divider can be set to integral values only according to the following formula:
D=[(S/(100*r))+0.5],
where:
S
– encoder constant,