華 彩 企 業 ( 香 港 ) 有 限 公 司
SOL Enterprises (Hong Kong) Limited
Bar codes consist of combinations of spaces and bars, light and dark patterns, to encode characters. The bar code reader measures the different spaces and colors and compares them to the encoding table for that type of bar code (called a symbology) and decodes the symbol.
There are many types of scanners available for different purposes. Fixed mounted scanners are commonly found at POS or on conveyor belt. Handheld scanners are commonly used in many general purposes. Some models are in rugged packaging, which are more durable to withstand industrial conditions. PDA or mobile computing terminals with built-in scanners or imagers are also very popular among logistics industry for performing multipurpose applications.
At first a label format needs to be created with a software, which must support bar coding programming. Once the label is created, a printer capable of printing bar codes and supporting its symbology is required. It is essential that the printer is of good quality to get accurate lines, light and dark bars, and get the exact space between the lines to produce a readable bar code. At last the media must support bar code print quality by not running, fading, or otherwise deforming the symbol.
There are two basic types of bar code symbologies distinguishable between the many bar codes that have been created, the linear and two-dimensional (2-D) types. The linear type encodes the data in a single line with bars and spaces (example U.P.C./EAN symbol). The 2-D type encodes data in a matrix form where multiple linear symbols are stacked on top of each other, or contains blocks or lines in a grid or geometric pattern. PDF417, Aztec Code and Data Matrix are the most common forms of 2-D symbologies.
There are three major types of scanning, namely laser scanning, linear CCD Scanning and imaging. Laser scanners is likely to be the most common technique in use in today. It uses a laser bean as the light source and typically employs either a reciprocating mirror or a rotating prism to scan the laser beam back and forth across the bar code. CCD scanners send out LEDs' red light instead and use an array of hundreds of tiny light sensors lined up in a row in the head of the reader to receive signals reflected back from the symbol. Imagers are also known as camera-based readers. It can read both 2D symbols and linear symbols by using specialized digital image processing techniques to decode the barcode.
Direct thermal and thermal transfer are two printing methods. Both use a thermal print head to apply heat to the surface being marked. The thermal transfer method uses a heated ribbon to print long-lasting or permanent images on a range of materials such as paper, film, and even foil substrates. This method is excellent for high-density barcodes and labels that require longevity. The direct thermal method uses no ribbon but prints the image directly on the heat activated thermal labels. Over time the labels will darken and become less crisp, particularly when subjected to heat and sunlight. Since its possibility to print on different materials is limited, direct thermal is mostly used to print shipping labels, picking/put away labels and receipts. Since no ribbon is needed, it also costs less comparatively.