CCD, Laser, Imager Barcode scanners
Scanners of bar code, like all other digital devices, the work on the binary code. The bars and spaces in a bar code represent 1s and 0s of binary code. When the scanner light bar code reflects the barcode, the computer can decipher the binary code on factual information, which may vary from item name, cost, date of manufacture, expiration, discounts, etc. The more information required the bar code, the higher the bar code.
A CCD scanner uses an array of hundreds of tiny light sensors lined up in a row in the head of the sensor. The CCD reader is extremely sensitive and small because of the hundreds of sensors. A voltage pattern commensurate with the pattern in the bar code is created in the reader by measuring voltages across each sensor in a row. The most important difference to remember when using a CCD scanner is that it is measuring ambient light versus the use of a laser.

The CCD barcode scanners typically have the advantage over laser scanners in several applications. CCD scanners have no moving parts which make the CCD scanners less prone to failure. The laser scanners have oscillating mirrors which are subject to wear and mechanical failure, unlike CCD scanners. CCD scanners use LEDs for light illumination and last about ten times as long as laser light diodes. 

Lasers typically have a warning label associated with direct viewing and safety precautions need to be taken. Because CCD scanners do not use lasers, there are no precautions that need to be taken for a safe viewing distance. The CCD scanners have scan rates of 45 scans per second or faster, which is comparable in speed to the laser scanners. CCD scanners are also much lighter and less expensive than laser scanners.

Laser scanners also exhibit some advantages over CCD scanners. Laser scanners have a more powerful light emission which means they can be used further from the barcode. The laser scanners have a greater depth of field or operating range. For this reason, the laser barcode scanners are good when used by a particularly untrained worker. The laser scanners, depending on the model, can be operated several feet away from the barcode, while the CCD scanner needs to be within several inches in order to work effectively. Laser scanners can read longer bar codes than CCD scanners. CCD units are usually limited to a barcode length of three or four inches.

CCD Barcode Scanner
A CCD Barcode Scanner can read barcodes quickly, work as Laser Barcode Scanner, but with some limitations. Can read at short range no more than 3 inches of the printed barcode. The barcode is generally illuminated by a photocells diodes built into the scanner. The CCD Barcode Scanner has a limited width for sizes of barcodes and cannot will read. To use CCD Barcode Scanner, hold scan button, point to barcode and release button. This is more slow in comparison with Laser Barcode Scanner readings, but more atractive by low price and are used commonly in point of sale applications for scanning purposes.
Laser Barcode Scanner
A Laser Barcode Scanner are the most popular. Work same that pen readers with a single photodiode designed to emit and detect. The laser source light is tuned in a specific frequency permitting that recognize light reflected back from the barcode.To use a Laser Barcode Scanner , hold scan button, point barcode and release button. A Laser Barcode Scanner can read printed barcodes from 6 to 30 feets away vary by model as standard, long range and extra long range. Suitable for high work activities it can read quickly and accurately, available for rugged applications at affordable price.
Imager Barcode Scanner
A Imager Barcode Scanner use a CCD video camera to capture an image and then use sophisticated image decode techniques to interpret two-dimensional (2D) and PDF417 printed barcodes, . A Imager Barcode Scanner use hundreds row of sensors to read large amount of data contained in data point matrix. To use Imager Barcode Scanner simply point 3 to 9 inches away barcode, hold and release button, data will be readed quickly and accurately. Its ideal for a wide spectrum industry like postage, sending and receiving.