Scanners

Objectives :

• Identify the different types of scanners

• Explain the different parts of a scanner

• Explain the working of a scanner

• Install different types of scanners

• Configure a scanner

• Calibrate a scanner

• Troubleshoot scanners

Types of Scanners :

Most widely used type of scanners

Similar to a photocopy machine in appearance

Also known as desktop scanner

Used for scanning sheets of paper

Very versatile in scanning loose sheets of paper

Cannot scan bound documents

Scan photo slides

Enables people to digitalize photographs

Use to restore old slides

Used for high-quality applications

Uses a Photomultiplier Tube (PMT)

More costly than other types

Structure of a Scanner :

Structure of Scanner Consist of :

• Front of the scanner - Contains a power indication light to display working status of scanner. Light blinks when a scan is in progress. Some scanner also have a power on/off button

• Scanner cover - Protects scanning surface from dust and other external articles and provides a background for the scanning process

• Back of the scanner - Contains different ports for connecting scanner

Working of a Flatbed Scanner :

Document you want to scan must be placed face down on the glass plate of the scanner

Scanner lamp illuminates on to the paper after the cover is closed

Belt in the scanner moves the scan head comprises of :

• Mirrors, lens, filter and a charge-coupled device (CCD) array

Stabilizer bar ensures that the movement of scan head along the document is smooth

Scan head captures the light reflected from the document

Light captured by the scan head is reflected onto a mirror

Mirrors constantly change their position to align the light with the scanner lens

Lens focuses the light signal through a filter to the CCD array

CCD array converts the light signal to an electric signal

Analog to Digital Converter (ADC) converts the electric signal to thousands of digital pixels of data

Scanner driver converts the scanned image to a format that can be understood by the computer

Installing a Scanner :

Scanner can be connected to parallel port, SCSI port or USB port of a computer

Read manual for instructions on settings for the scanner and also to run a test scan. Many scanners come with additional software. Read documentation that comes with scanner and install any additional software if it comes with your scanner

Calibrating a Scanner :

A scanner should be calibrated once a month in order to get best results

Calibration of a scanner removes the necessity of repetitive editing of images

Ensure that images on monitor or on a printed page are identical to the output from scanner

Before calibrating scanner, make sure that the printer and monitor are calibrated

Scan an image

Compare colors on scanned and original image

Build a profile to correct scanner’s production of colors

Refer to manual

Set profile as a scanner profile

Troubleshooting :

Scanner problems are :

• Computer does not recognize Scanner

• Computer does not start

• Scanner does not work

• Scanner does not work properly after a system crash

• Cannot access USB scanner

• Scans are not clear

Check whether scanner is plugged in and power switch is on

Shut down the computer and unplug it

Check USB or SCSI port of scanner for proper connection

Remove parallel port cable and inspect properly for any signs of damage

If the SCSI scanner is the last SCSI device, you must attach a SCSI terminator plug to the scanner or use a dip switch.

Check whether correct scanner is selected

Reconnect appropriate cable to the computer properly

Plug in the computer and turn it on

Try interchanging cables of the power outlet and computer

Problem occurs :

• If scanner is not terminated properly when multiple SCSI devices are connected

• If two SCSI devices have the same ID

To resolve the problem :

• Shut down computer and turn off scanner

• Properly set the ID numbers and terminations

• Turn on the scanner first and then computer

Confirm power is on and scanner is also turned on

If there is no power in scanner, swap power cable with another one

Try a test scan to ensure a problem is with installation or configuration of computer

Ensure document or image to be scanned is placed face down on glass

Wait till light stops blinking before lifting scanner lid

Check power on scanner

If power light does not come on, check power cord of scanner

Check power outlet by connecting another device to it

Check if the USB cable is connected securely

For multiple USB devices, use a powered USB hub for powering the devices

Restart the computer