Industry:
Printing Equipment
Manufacturing
Application:
Differential Speed
Measurement
Printing equipment manufacturer
controls paper stretch and eliminates
print registration problems
Profile:
A leading manufacturer of digital imaging
and printing technology
Solution:
LaserSpeed® 9000-303
Results:
 Control stretch and slippage to
eliminate registration problems
 Accurate, reliable speed measurements
 No encoder recalibration
 Easy setup and use
Digital printing press
In the printing industry, registration is the method of correlating
overlapping colors on one single image. Each color, in a multi-color
image, is applied in a separate step and ultimately lined up so the
various components of the image are in their proper place. But,
synchronization issues between the web speed and the print heads
on the printing press can create very slight misalignments known
as registration errors between printing each color. This causes
unintended color fringing, blurring, or light/dark streaking along
the edges of colored regions. Moreover, this can vary considerably
from process to process. It generally requires that the substrate,
typically paper, is in correct alignment with the print heads.
The Challenges:
Differential Speed Measurement
A U.S. based printing equipment manufacturer was having a
registration problem on one of its digital printing machines at
its R&D center. During product testing, the product engineers
recognized that the registration of the cyan, yellow, magenta,
and black colors in the printer’s multi-color process were off
by several microns. This condition was a recurring problem.
The engineers believed that the problem could be due to one or
more of the following reasons:

Paper stretch due to tension or the applied ink

Paper slippage on the drive roller

Differences in mechanical wheel encoder speed
versus actual web speed
The Solution:
Most printing press systems use encoders on the drive rollers
or contact wheel encoders riding on the substrate to measure
the speed of the web during printing processes. While drives
on drive rollers are becoming sophisticated and more
accurate, the simulated encoder output from the drive cannot
compensate for slippage. Every substrate has some amount of
slipping on the drive roller. The amount that this material slips
can vary based on texture, composition, or even tension at
other points on the line. A contact encoder attached to the
drive roller has the same problems.
A contact encoder riding on the web has even more problems.
The wheel can either wear down or have dirt build up, both of
which change the calibration. This, along with the same types
of slippage problems, makes any sort of contact measurement
a poor choice when high accuracy is desired.
LaserSpeed® 9000-303
After investigating several alternative measurement
technologies, the printing equipment manufacturer selected
Beta LaserMike’s differential speed measurement system. This
solution includes the LaserSpeed Length Differential Indicator
(LDI) and two LaserSpeed 9000-303 non-contact encoders.
The LS9000-303 encoder uses laser-based technology that
projects a unique pattern on the surface of the substrate. As
the product moves, light is scattered back to the LS9000-303
encoder. This information is translated into product speed.
The LS9000-303 can read forward and backward product speed
up to ±4,000 m/min (±13,100 ft/min). Speed measurements
are captured with better than ±0.05% accuracy.
Used as a diagnostic tool, the product engineers can use this
differential speed measurement system to monitor the line
speed of the printing system at any two locations on the web.
Since the LS9000-303 encoder measures the product itself and
not a roller, slippage is not a problem. Adding the fact that the
LS9000-303 encoder has a measurement accuracy of ±0.05%,
the stretch measurement will be reliable and correct.
LaserSpeed LDI System
Critical Process Factors. The engineering team wanted to ensure
there was no paper stretch and that all drive rollers were
pulling the product through the press at the same speed. This
meant the non-contact encoder system needed to measure the
differential speed with the highest degree of accuracy and
repeatability. The encoder also had to be compact and rugged,
so it can installed at any location on the press. Another
critical factor was the ability of the encoder to reliably read
any material surface, as the paper substrate and coatings
may change from application to application. One final factor
required the non-contact laser encoder to provide the same
outputs as a contact encoder. This allowed for simple
plug-and-play installation with minimal modifications
required to the printing press and current web control process.
Installation. Gauge mounts are installed at several points
along the line, enabling the LS9000-303 encoders to be
positioned at two different desired locations to determine the
differential speed between the drive rollers and the web. The
encoders are positioned perpendicular and 12 inches from
the web. This setup allows the product engineers to monitor
and measure web tension at critical points for paper stretch,
as well as monitor paper slippage on the drive roller. The
LDI system is also used to compare speed measurements from
the contact wheel encoder and LS9000-303 gauge via direct
input of encoder pulses. The LDI system includes an RS-232
output which can be interfaced with a PLC to control the
differential speed.
The Results:
Beta LaserMike’s differential measurement system with LaserSpeed encoders offers the printing equipment
manufacturer a number of key benefits:

High accuracy and repeatability

Low cost of ownership due to no moving parts

No slippage problems from non-contact method

Permanent calibration for increased uptime

Compact design for installation flexibility
As the R&D team at the printing equipment manufacturer continue to use the LaserSpeed system,
Beta LaserMike will learn more about the long-term value of the solution.
Beta LaserMike’s LaserSpeed non-contact encoders are the most
accurate, reliable, and cost-effective measurement solution for
controlling stretch or draw of product during manufacturing.
To learn more, visit: www.laserspeedgauge.com
Beta LaserMike USA
8001 Technology Blvd.
Dayton, OH 45424 USA
Ph: +1 937 233 9935
Fax: +1 937 233 7284
Beta LaserMike Europe Beta LaserMike Asia
Unit 3, First Avenue
Globe Park, Marlow
Buckinghamshire, SL7 1YA
United Kingdom
Ph: +44 1628 401510
Fax: +44 1628 401511
Unit 401, Xinmao Plaza,
Building 9, No. 99 TianZhou Rd.
Shanghai 200233, China
Ph: +86 21 6113 3688
Fax: +86 21 6113 3616
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