How scanner work

• The document is placed on the glass plate and the cover is closed.

• The cover provides a uniform background that the scanner software can use as a reference point for determining the size of the document being scanned.

• A lamp is used to illuminate the document. The lamp in newer scanners is either a cold cathode fluorescent lamp (CCFL) or a xenon lamp, while older scanners may have a standard fluorescent lamp.

• The entire mechanism (mirrors, lens, filter and CCD array) make up the scan head. The scan head is moved slowly across the document by a belt that is attached to a stepper motor.

• The scan head is attached to a stabilizer bar to ensure that there is no wobble or deviation in the pass.

• The image of the document is reflected by an angled mirror to another mirror.

• The last mirror reflects the image onto a lens. The lens focuses the image through a filter on the CCD array.

• After the three passes are completed, the scanner software assembles the three filtered images into a single full-color image.