4VAL Operating & Maintenance Manual Version 1.1 © Newman Labelling Systems Ltd Page 34 of 56
4.5 LABEL SENSORS
Label sensors detect gaps between successive labels on the web and a second sensor
may be used to prevent a double label feed if a label is missing from the web. Several
forms of label sensor can be used dependent on the label and web material. Optical
sensors are common but they are not suitable for transparent labels. In such cases,
either a mechanical or ultrasonic sensor is fitted. In all cases the function of the
sensor is to stop the label feed at the appropriate moment. Subject to label type, and
therefore type of sensor fitted, refer to the appropriate section below.
4.5.1 FORK LABEL SENSORS
Photoelectric label sensors used for paper labels. The procedure for setting is: -
•
Set Label Sensor 1 before Label Sensor 2.
•
Place the web without labels into the slot in the sensor so that the label web
only can be read.
•
Press and hold the AUTO SET pushbutton until the green READY LED turns
OFF. This starts the acquisition phase of the object to read which must not be
removed until the green LED blinks.
•
When the green READY LED blinks, pull the web until a label is in the slot of
the sensor using the reference marks on the tip for alignment.
•
The green READY LED continuously ON indicates the setting is completed
and the sensor is ready.
•
Re-check along the label to ensure that the LED will only come on when it
reads a gap.
•
Set the second sensor nearest the stripper plate in the same manner as the first
BI-COLOUR
LED
GREEN READY
RED ERROR
LABEL
SENSOR 2
LABEL
SENSOR 1
AUTO SET
PUSHBUTTON
LED YELLOW
(OUT)
