Scanners

- Ray Kurzweil invented scanner in 1840s.

- Scanner is a device that captures images from phtographic prints, posters, magazine pages.

- High resolution scanners are used for scanning high reolution printing.

- Scanners come with software, such as Adobe's Photoshop, lets you resize and modify image.

- Scanners usally attach to your PC with a small Computer System Interface.

How Scanners Work

1. Image tobe scanned is placed on top of scanner's glass plate.

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

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

4. Scanning unit moves across image to be scanned at a speed designated by logicboard instructions.

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 scanner lens.

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

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

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

10. The digital signals from 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.