Thursday, February 18, 2016
Posted by Sandeep Kumar Jha
- The document is placed on the
glass plate and the cover is closed.
- The inside of the cover in most
scanners is flat white, although a few are black.
- 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.
- Most flatbed scanners allow the
cover to be removed for scanning a bulky object, such as a page in a thick
book.
- 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.
- Pass means that the scan head
has completed a single complete scan of the document.
- 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.
