4VAL Operating & Maintenance Manual Version 1.1 © Newman Labelling Systems Ltd Page 37 of 56
4.6 DOUBLE LABEL FEED INHIBITOR
The above sections detail the different types of label sensors used to suit various label
types. Two sensors are used with the ‘Double label feed inhibitor’ feature to ensure
that if a label is missing from the web only one label will be dispensed. To enable this
function, two sensors are fitted and the control system will accept a stop signal from
either sensor. This requires both sensors to be set at the correct label pitch. Pitch
adjustment is achieved using the coarse and fine adjustments on the label sensor
mounting brackets.
4.7 OVERPRINT SENSOR
An Overprint Sensor (blob detector) is fitted to the labelling machine to verify the
presence of an overprint on the label. The sensor is essentially a contrast detector that
is typically used to detect black overprint on a white background and has a sensitivity
adjustment to detect this contrast. When an overprint is detected, the sensor sends a
signal to the control system. The sensor mounting has both vertical and horizontal
adjustments for correct alignment with the overprint.
Overprint sensor adjustments
•
The sensor should be positioned next to the coder so that overprinting failure
is immediately detected, but clearance space has to be given between the units
for access to the coder and to the sensor adjustment screw and locking handle.
•
The label web must be stationary to set the sensor and also be in the correct
stopping position.
Vertical
Locking
Handle
Vertical
Adjusting
Handle
Horizontal
Locking
Handle
