OPTICAL SCANNER

GEOMETRY/STRUCTURE:

	Item	Purpose
1.	Stepper Motor	Powers the transmission belt
2.	Logic Board	Relays information to and from the scanner and the computer
3.	Scanning Unit/Carriage	Contains a light source and CCD sensors
4.	Transmission Belt	Moves the scanning unit across the image
5.	Flex Circuit	Carries the CCD information to the logic board
6.	CCD sensors	Converts measured reflected light into a voltage proportional to the light intensity
7.	Glass Plate	Allows light to pass from light below glass to image and supports image
8.	ADC	Analog digital converter unit that changes CCD measured voltage to digital

EXPLANATION OF HOW IT WORKS/ IS USED:

1.     The image to be scanned is placed on top of the scanner’s glass plate

2.     The computer sends instructions to the logic board about how far the motor is to run and how fast

3.     The logic board instructions place the scanning unit into an appropriate position to begin scanning

4.     The scanning unit moves across the image to be scanned at a speed designated by the logic board instruction

5.     As the scanning unit moves across the image, a light source shines on the image

6.     The light strikes the image, reflects, and is then reflected by a series of mirrors to the scanner lens

7.     The light passes through the scanner lens and reaches the CCD sensors

8.     CCD sensors measure the amount of light reflected through the image and converts the light to an analog voltage

9.     The analog voltage is changed to digital values by an ADC  – analog to digital converter

10. The digital signals from the CCDs are sent to the logic board and transmitted back to the computer

The information is stored in the computer as an electronic file made up of pixels.   The group of pixels is changed into a picture by the TWAIN scanning software.


A COLOR SCANNER VS BLACK AND WHITE SCANNER

1.     Black/white scanners only have one light source, and color scanners have three light sources, one for each primary color—red, green, blue.

2.     Color scanning can be achieved by a one-pass scanner or a three-pass scanner.

3.     A one-pass scanner scans the image once and records all three colors at the same time, while a three-pass scanner makes three passes over the image and records only one color each pass.

A device that converts printed images and text into digital information that can be edited, transmitted, and stored. Optical scanners work by electronically measuring the intensity of color at a large number of individual locations across the page (often using phototransistors), and converting these measurements into digital numerical values usable by computers and other digital devices.