Bar Code Scanning

In a bar code system, the scanner (or reader), as the name suggests, is the device which actually reads the bar code symbol. The scanner interprets the bars and spaces by directing a beam of light at the bar code symbol. The scanner "reads" by recording, digitizing and decoding the pattern reflected back from the symbol. The dark bars absorb the light and the spaces or "light" bars reflect the light.

There are many different types of scanners available but they can be divided into two main categories: contact and non-contact. Contact readers or scanners are normally hand-held devices, while non-contact scanners can either be hand-held or stationary units.

Contact Scanners

Contact scanners are those that must either touch or come in close proximity to the bar code symbol. Wands (also know as light pen) and CCDs (Charged Couple Devices) are examples.

Contact scanners are a good choice when it is not possible to convey coded items past a scanner, or where the label cannot be placed in an easy-to-view position.

Many benefits come from using contact scanners to scan bar codes, including a reduction in the number of clerical errors in recording data; a reduction in labor and paperwork to process data; faster and more accurate inventory tracking; and enhanced efficiency of forms and document tracking/control.

Non-Contact Scanners

Non-contact readers, as the name suggests, do not have to be in close proximity to the bar code symbol in order to read it. They can read a bar code up to a distance of several feet, depending upon symbol size and scanner design.

Non-contact scanners employ either a moving beam or a stationary beam. Although non-contact scanners most commonly have a moving beam laser light source, fixed-beam scanners are available, as are non-contact scanners, employing other light sources such as infrared or visible red.

Non-contact scanners come in both hand-held and fixed mount configurations. The hand-held scanners offer the ability to scan bar codes almost anywhere. Therefore, these devices are found in almost any type of application, including point-of-sale retail, warehousing, manufacturing, and field service. They are particularly suitable where mobility is needed.The fixed position laser scanners are used in hands-free and unattended applications. These units are ideal for applications where the item is moved past the scanner. Some common applications are: distribution centers using high speed sortation, work-in-process tracking in manufacturing facilities, high-speed checkout, and baggage handling systems.