Elements of Barcoding System
· Barcode printer
For printing of barcodes, four types of printers are typically used: Dot matrix, Laser, Thermal transfer and Direct thermal printer. Dot matrix printers produce labels with low print quality but at low cost. Laser printers produce good quality at moderate costs. Thermal transfer prints labels at very high quality at higher cost. Direct thermal printers prints labels with very high quality at moderate costs, but labels are sensitive to heat/light and are recommended for indoor uses only.
· Barcode Label
Labels contain product specific information encoded into a barcode. These can be used on products or their parts, packages, tickets/ receipts, shipping containers, etc. allowing the item to be identified and. Bar codes need not be only adhesive labels, but also can be printed on receipt paper, tickets, tags and plastic cards, depending on the application
· Barcode Scanner & Decoder
Scanners read & capture the information contained in a barcode. It extracts information optically from a Bar Code. When Barcode symbols are illuminated, reflected light is detected by electro optical sensor. The intensity of reflected light from the dark bars is less than that of spaces. Reflected light is converted into electrical voltage signals. Analog voltages are digitized into raw data. Raw data is fed to the decoder which decoder converts this data into the character data representation of the symbol’s code. Scanner may or may not have in-built decoder.
Scanners are available in following types:
· Contact type:
These types of readers must touch or come in very close proximity to the symbol. They are generally pen or wand type and are handheld/stationary units. These have a LED and a photo diode in the tip of a pen or wand. The pen is dragged across the barcode to capture it. The photo diode measures the intensity of the reflected light. One of the commercially available such type of scanner (Make: Unitech) is shown in forthe figure:
· Non Contact type:
They need not come in contact with the symbol. Scan distance may range from few inches to a few feet depending upon symbol size and scanner design. They are handheld, fixed beam readers. They are available in the form of laser scanners, CCD scanners and imagers.
Laser barcode scanners use a laser beam instead of LED and use a reciprocating mirror or a rotating prism to scan the laser beam back and forth across the bar code. Photodiode measures the reflected light. CCD scanners use LEDs as light source an array of tiny light CCD sensors for detecting the received light. Imager type uses a camera to capture the code and digital signal processing techniques to decode the code.
Various types of such commercially available scanners in various form factors are shown in the following table.
The functionality of a typical laser scanner is explained below. However, the steps are equally valid for both pen or wand type reader as well.
· PC with product database
Database forms a vital part of bar-coding system. Each barcode must be mapped to an entry in the database. Database contains variety of information like product description, price, discounts, etc corresponding to a barcode. Without proper database, bar-coding system has no significance.
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