Scanners

Parts of a Scanner
Charge-coupled device (CCD) array
Mirrors
Scan head
Glass plate
Lamp
Lens
Cover
Filters
Stepper motor
Stabilizer bar
Belt
Control circuitry




Charge Coupled device (CCD)
One of the two main types of image sensors
used in digital cameras.
When a picture is taken, the CCD is struck by
light coming through the camera’s lens.
Each of the thousands or millions of tiny
pixels that make up the CCD convert this light
into electrons.
The number of electrons, is then converted to
a digital value.




Document Reader
Data is read directly from the source
documents.
Mark reader
Character Reader

Mark Reader
Sends a thin beam of light on to the paper
Detects the reflected light
Dark pencil mark absorbs the beam
i.e. Multiple choice examination

Optical Character Reader
Alphabets and numbers can be read by
special machines
Can also be read by human
Uses a light source to read characters
Converts them into electrical signals
Sends to the computer for processing

OCR
Application
One useful application of OCR is in the
processing of turnaround documents. A
turnaround document is a document printed by a
computer. Later, when extra data has been
added, the document is read by an OCR reader
and the data is input to the computer for
processing.
For example, turnaround documents may be
used by gas or electricity boards to collect meter
readings from all their customers. The stages in
the data processing are....
The computer prints out a meter reading sheet
for each customer in an OCR font showing their
name, address, meter number and other details
The meter readers read the meters and add the
readings to each sheet. They may use careful
hand-written figures to record the readings.
The completed meter reading sheets are input
using an OCR reader, and the computer
produces the bills.
OCR reader speeds of up to 1500 sheets per
minute may be expected.