Olivetti PR2 PLUS, Service Manual, Page: 72 / 172

4-18 Service Manual
XZAC4219-05
CALIBRATING THE PHOTOSENSORS
Machine photosensors are calibrated at the factory. Changes in the electrical characteristics of the photosensors or
the use of particular paper may require further calibration at the customer site.
Machine photosensors that must be calibrated are:
•
« Paper present » photosensors
Consist of two LEDs and two photo-receivers and are the first to detect insertion of the document in the front
slot. The light beam is transmitted by optical fibers.
•
« Front paper alignment » photosensors
Housed in the same mechanical unit as the paper present photosensors, indicated in this manual as front
photosensors assy. The front paper alignment photosensors check alignment of the document before this
moves close to the printhead. They consist of four LEDs and the same number of photo-receivers, all coupled
by optical fibers.
•
«Autoborder» photosensor
Is fitted on the printhead and detects the presence of the paper in order to measure the position of the first print
column. This photosensor also permits (if selected from set-up) control of printing interrupt functions if the paper
is narrower than the print line sent by the system.
The position in the machine of the individual photosensors is shown in the following figure.
Figure 4 - 2 Locating the machine photosensors
Back of the printer
Front of the printer
Ph
oto N
o
1 Paper present
Ph
oto N
o
2 Paper present
Optical fibers
Optical fibers
Optical fibers Optical fibers
Photo N
o
1 Photo N
o
2 Photo N
o
3 Photo N
o
4
Paper alignement photosensor
Paper edge
Impact head
carriage
detection photosensor