Barcode Scanner 

Barcode (also bar code) is a machine-readable representation of information in a visual format on a surface. Originally barcodes stored data in the widths and spacings of printed parallel lines, but today they also come in patterns of dots, concentric circles, and hidden in images. Barcodes can be read by optical scanners called barcode readers or scanned from an image by special software. Barcodes are widely used to implement Auto ID Data Capture (AIDC) systems that improve the speed and accuracy of computer data entry.A barcode scanner (or barcode reader) is a computer peripheral for reading barcodes printed on various surfaces. Like a flatbed scanner, it generally consists of a light source, a lens and a photo conductor translating optical impulses into electrical ones. Additionally, nearly all barcode scanner or readers currently produced contain decoder circuitry analyzing the barcode's image data provided by the photo conductor and sending the barcode's content to the scanner's output port. It is used in many important places like -Supermarkets -ID recognition -Product ID Recognition -Book Tag Identification.

Types of Barcode Scanners

Many different types of barcode scanners are available. They can be distinguished as follows:

1- By light source

LED scanner : Also referred to as CCD scanners, even though the CCD is in fact the photo imaging sensor, not the light source.

Laser scanner : Scans one dimensional or "linear codes". Typically less rugged than LED scanners since they have moving parts.

2D Imaging scanner : These scanners take a 2D image of the barcode as in a camera and can be used to scan 2D barcode types such as Datamatrix as well as the more common linear barcode types.

2- By housing

Handheld scanner : With a handle and typically a trigger button for switching on the light source.

Pen scanner (or wand scanner) : A pen-shaped scanner that is swiped.

Stationary scanner : Wall- or table-mounted scanners that the barcode is passed under or beside. These are commonly found at the checkout counters of supermarkets and other retailers.

Fixed position scanner : An industrial barcode reader used to identify products during manufacture or logistics. Most often used on conveyer tracks to identify cartons or pallets which need to be routed to another process or shipping location.

PDA scanner : A PDA with a built-in barcode reader or attached barcode scanner eg Grabba.

Types of Connectors

Most barcode readers use a PS/2 or USB cable for output. PS/2 cables are connected to the host computer in a Y formation, the PS/2 keyboard port with its first end, to the keyboard with its second, and to the barcode reader with its third end. The barcode characters are then received by the host computer as if they came from its keyboard decoded and converted to keyboard input within the scanner housing. Many readers can also be equipped with an RS-232 output port so that the decoded characters arrive at the computer via one of its RS-232 connectors. USB is supported by many newer scanners, in many cases a choice of USB interface types (HID, CDC) are provided.

There are a few other less common interfaces. The proprietary IBM interfaces that use an SDL type connector and are based on an RS485 protocol. OCIA is sometimes still found, mostly used on older stand alone cash registers with a wide variety of connector types. Undecoded interface is an amplified output of the raw wave received back from the barcode and requires a decoder to be built into the terminal that the scanner connects to which is more common on industrial terminals. Wand emulation is another output type that takes the raw wave and decodes it, normalizing the output so it can be easily decoded by the host device. Wand emulation can also convert symbologies that may not be recognized by the host device into another symbology that can be easily decoded.

Types of Symbologies

Today's barcode scanners handle all popular barcode symbologies like EAN/UPC, Code 39, Interleaved 2 of 5 or Code 128. A special type of barcode reader is the area imager reader or 2D reader that typically uses LED illumination and a CCD or CMOS imager that operates much like a digital camera. These are necessary for decoding two-dimensional matrix codes such as Data Matrix, QR Code, Aztec Code and MaxiCode in addition to linear and stacked symbologies. Certain code types such as PDF417 and RSS can have stacked components similar to matrix barcodes, however these code types can be read both by linear scanners and also 2D scanners.