A barcode scanner, also called a point-of-sale (POS) scanner or a price scanner, is a device used to capture and read information contained in a barcode. The scanner consists of a light source, a lens and a light sensor that translates optical impulses into electrical ones. They also contain decoder circuitry analyzing the barcode’s image data provided by the sensor and sending that content to a computer.
A barcode scanner works by directing a beam of light across the barcode and measuring the amount of light that is reflected back. The dark bars on the barcode will reflect less light than the white spaces between them. The scanner then converts the light energy into electrical energy, which is then converted into data by the decoder and forwarded to a computer.
The most common kinds of scanner used to read one dimensional barcodes are, pen wands, slot scanners, Charge Couple Device (CCD) scanners, image scanners and laser scanners.
A pen wand scanner contains no moving parts and is known its durability and cost. The pen needs to stay in direct contact with the barcode, be held at a specific angle and be moved across the barcode at a certain speed.
A slot scanner remains stationary and the item with the barcode is pulled through the slot by hand. Slot scanners are usually used to scan barcodes on identification cards.
A CCD scanner has a better read-range and doesn’t involve contact with the barcode. This makes it ideal for use in retail sales. Typically, a CCD scanner is used as a “gun” type interface and has to be held no more than one inch from the barcode. Several different readings are made to reduce the possibility of errors, every time a barcode is scanned. A disadvantage to the CCD scanner is that it can’t read a barcode that is wider than its input screen.
An image scanner, also known as a camera reader, uses a small video camera to capture an image of the barcode and then it uses sophisticated digital image processing techniques to decode the barcode. An image scanner can read a barcode from about 3 to 9 inches away and usually costs less than a laser scanner.
A laser scanner can either be handheld or stationary and doesn’t need to be close to the barcode in order to read it effectively. The scanner uses a system of mirrors and lenses that allow it to read barcodes regardless of their position and it can easily read up to 24 inches away from the barcode. A laser scanner may perform up to 500 scans per second, to reduce the possibility of errors. Specialized long-range scanners are capable of reading a barcode up to 30 feet away.
A 2D (two-dimensional) barcode is a graphical image that stores information both horizontally, as is the case of one-dimensional barcodes, and vertically. As a result of their construction, 2D barcodes can store up to 7,089 characters, significantly greater storage than is possible with the 20-character capacity of a one-dimensional barcode.
2D barcodes are read with a camera and image processing techniques to decode the barcode. Most 2D barcodes are optimized to be read by cell phones, as well as QR Codes and Data Matrix codes which can be read quickly and accurately with or without auto-focus. These have opened up a number of applications for consumers.