HP 3150 EN - Manual (Page 83)

EN Document scanner system 81
Document scanner system
The document scanner system consists of the optical system and
document pickup and feed systems.
The optical system, also known as the contact image sensor, contains
the following:
● light-emitting diode (LED) array
● contact glass
● rod lens array
● phototransistor array
The LED array, which emits light from two types of LEDs, is controlled
by the formatter. The contact glass refracts the light to documents.
Light reflected from documents passes through the rod lens array to
the phototransistor array.
The phototransistor array consists of 2,574 phototransistors: 11 driver
circuits that amplify the light reception output in units of 234
phototransistors. The image data is converted and sent from the
driver circuits to the formatter.
The document pickup and feed systems contain a pickup roller, a feed
roller, and a delivery roller, all of which are driven by the document
scanner motor. There are also two photosensors in the document
path. PS801 detects the presence of a document and PS802 detects
the leading edge of a document.