4VAL Operating & Maintenance Manual Version 1.1 © Newman Labelling Systems Ltd Page 41 of 56
4.11 MISSING LABEL DETECTION
The missing label (UV) sensor works together with the reject sensor (missing label
presence sensor) to confirm label presence on containers. The missing label sensor has
a relatively wide range (field of view) and the reject sensor has a fairly narrow focus
(field of view). Hence quite a long signal will be received from the missing label
sensor and quite a short signal from the reject sensor. The timing of these signals must
be such that the UV sensor signal comes on first and then the reject sensor.
The diagram below shows the ‘long’ UV signal and the ‘short’ reject sensor signal.
No. 1 is the ideal set up.
No. 2 shows the reject sensor early but still acceptable.
No. 3 shows the reject sensor late but still acceptable.
No. 4 shows the reject sensor too early and this will stop the machine.
UV Sensor Timing (29920a)
