What is Barcode Scanner

The barcode scanner is a device that reads the barcode and converts it into numbers and letters. It is connected to the computer to store the numbers and letters that are decoded, using a cable via the serial port or the keyboard wedge. A decoder circuitry is present in the scanner that is used to decode the barcode image with the help of a sensor.

The barcode is a set of vertical lines and spaces. The lines or bars of the barcode are differentiated from each other according to the width and space of the bars. It includes a start bit, stop bit and sometimes contains the checksum bit. The checksum bit checks for the accuracy of the barcode.

The barcode scanner consists of a laser source and a photo sensor. The scanner decodes the barcode into electrical signals and gives to the computer. The computer must have a scanner software installed in it, which helps to convert the electrical signals from the scanner, to numbers and letters. There are different types of barcode scanners available, which are as follows:

Pen-type Scanner

The pen-type barcode scanners are pen-shaped and have a light source and a photo diode at the tip of the scanner. The light source falls on the barcode and the photo diode converts the reflected light of varying light intensity in a waveform. This waveform is fed to the computer via the cable. The scanner software converts the waveform to related data. The pen-type readers are available in different resolutions so as to read barcodes of different shapes and sizes. This type of scanner is less expensive and is easy to maintain.

Laser Scanner

The laser barcode scanner has the same working like that of a pen-type scanner, but its components are different. Laser scanners use laser beams as a source of light and reciprocating mirror or rotating prism for detecting the reflected light. The frequency of light source used in the pen-type and laser scanners is same and the light detecting devices like the photo diode and prisms are tuned to the same frequency.

CCD Scanner

CCD stands for charge-coupled device and is used in the barcode scanner. It consists of an array of tiny sensors placed at the tip of the scanner. The tiny sensors generate a voltage waveform and they are sequentially collected by the scanner and given to the computer for conversion. The basic difference between the pen-type and laser barcode scanners is that the pen-type measures the reflected light of specific frequency and the laser scanner measures the emitted ambient light from the barcode. They are widely used in sales applications.

Camera-Based Scanner

Advanced digital image processing techniques are used for decoding the barcode by the newest technology of camera-based barcode scanner. It contains a small digital camera inside the scanner and this camera directly captures the image of the barcode.

Portable data terminals are also available. These contain a Liquid Crystal Display (LCD). This portable terminal is in the shape of the palm and has an integrated scanner and a computing unit inside it. Some factors that must be considered while buying a barcode scanner are as follows:

• Environmental conditions (harsh or mild)
• Need of real-time system
• Distance between the scanner and the barcode
• Requirement of hands-free or hand-held scanners
• Need of continuous or periodic scanners

Barcode scanners are widely used in many stores, industries and libraries for access control and automatic identification purposes.