Reading (Scanning) Bar Codes and Information
Often users are unaware that a wand may not be able to read certain bar code densities. The wand resolution must be less than the bar code density. For example, a 5 mil wand can read a 10 mil bar code, however, a 10 mil wand cannot read a 5 mil bar code. General purpose wands can typically read up to 5 mils.
A simple way of determining the correct wand resolution for a specific bar code application would be to multiply the X dimension of the bar code by 0.7 and round up to the next whole number. For example, if you are using a 15 mil bar code, multiply 15 mil by 0.7 (10.5) and round up to the nearest whole number (11). Any mil size less than 11 would normally suffice for the application in our examples.
The wand works well in most applications and should be considered first when implementing a new bar code station or as a ÒhotÓ backup if an extra scanning device is required.
CCD readers range from about 2 inches to approximately 4 inches in width. The most common CCD readers measure roughly 3 inches. Of all the scanning devices, a CCD reader is the easiest to use. The user simply covers the bar code with the head of the scanner and pulls the trigger to activate the scanner.
The cost of a CCD scanner is about one-third the price of a laser scanner and about four times the cost of a wand. The CCD reader is a contact scanner in that user must have direct contact with the bar code label. If a wand is too difficult, too timely, or cumbersome to use, a CCD scanner could be an alternate solution.
A new technology related to CCD is Fixed Focus Optics (FFO). FFO technology utilizes the same principles as CCD technology, however, FFO scanners are non-contact readers. FFO readers can digitize a bar code from a distance of up to twenty inches from the label depending upon the resolution of the bar code. FFO promises to be a leading contender in the scanning market with the added capability of digitizing two-dimensional bar codes.
One of the newest technologies regarding laser scanning is “Fuzzy Logic.” Fuzzy logic technology applies artificial intelligence to reading poorly printed bar codes and is ideal for low-contrast, high density bar codes. Fuzzy logic offers the highest level of performance and best first-time read rate across a range of bar code qualities including harsh environments and rugged operating conditions.
Projection scanners are commonly used in material movement configurations. Both tabletop and fixed mount projection scanners are popular units at many checkout counters and conveyors systems respectively. Grocery store clerks move items across tabletop scanners almost as fast as it takes to remove the items from a cart alone. Likewise conveyor systems scan at a much higher rates than anyone is able to without making mistakes.
Laser technology is very popular in the United States primarily due to patent grants. Only a hand full of companies hold the central patents in this technology preventing further domestic and foreign competition. CCD technology is more popular among other countries because of this legal issue.
Every laser scanner has a depth of field. The depth of field is the range between the minimum and maximum distance in which a laser scanner can successfully read a particular bar code, and it is directly related to the density of the bar code. For example, the higher the density of the bar code, the closer the laser has to be to read a symbol. Likewise, the lower the density of the bar code, the farther away the laser has to be to read a symbol. There will be some overlap between the range of various bar codes, but as a general rule, the user must keep this is mind when scanning. In regards to bar coding, some common problems may exist with the set up. The table on the next page outlines some of these problems and the appropriate step(s) to take.
The magnetic stripe found on the back of credit cards and ID badges have a possibility of up to three "tracks" of data - Track 1, Track 2, and Tack 3. Each track has a different encoded format. Track 1 contains up to 79 alphanumeric characters while Track 2 and 3 contain only numeric characters. Track 2 contains 40 numeric characters, and track 3 contains 105 numeric characters. The banking industry use Tracks 1 and 2. Regulations required the customer's name to be encoded on the magnetic stripe along with the account number. In addition, the card holder number and expiration date are usually encoded. ID badges, on the other hand, use Track 2.
There are two types of magnetic encoding schemes: low-coercivity and high-coercivity. In regards to magnetic stripe technology, coercivity is the opposing magnetic intensity that must be applied to a material to remove the residual magnetism when it has been magnetized to saturation. In other words, a card encoded with high-coercivity has a less of a chance of accidentally being erased with, for example, a magnetized screw driver or magnetic clasp than a low-coercivity encoded card. Most card systems support both types of media, but high-coercivity is generally recommended especially for creating ID badges.
The best known applications for magnetic stripe are credit cards, time and attendance, personnel identification, and banking cards. Standards have been adopted for data densities, encoding methods, data content, recording qualities, and data formats. Magnetic stripe standards are mandatory in all financial systems, however, few standards exists for most other applications.
Other Identification Devices
With the advent of the personal computer, OCR technology has expanded in translating other stylized fonts such as Courier, Times Roman, etc. that are commonly found in newspapers, magazines, and other reading materials. Many manufacturers now describe this as Intelligent Character Recognition (ICR) since today’s OCR equipment is much more capable and much more powerful.
There are three categories of OCR/ICR readers: transaction readers, page readers, and hand-held readers. Transaction readers scan relatively short character streams and have the highest accuracy of all three types of readers. Page scanners digitize pages of text. Hand-held scanners are primarily used when transaction scanners are impractical and too expensive to use. Hand-held scanners also allow the user to have greater flexibility in scanning data outside a relative boundary or fixed position, for example, locating and reading the International Standard Book Number (ISBN) found on most published books which is printed usually somewhere on the back cover.
OCR/ICR is better suited in applications where human readability is required and where it is impractical to convert to bar codes. One of the most common OCR fonts, E-13B (MICR), is found at the bottom of nearly all personal checks and frequently used in point of sale, payment processing, and libraries.
RF Identification and Proximity Readers
RF tags are either active or passive. Active tags are usually more expensive because they can transmit a low-powered signal. These tags come with batteries and permit farther distances for RF identification. Passive tags do not come with batteries and are detected solely by the RF receiver.
The most common use of RF/ID is with toll tags. Other applications include personnel monitoring, security access, and package sorting.
Touch memory is widely used by the US Postal Service for tracking collection times on its large collection boxes. Healthcare, transportation, and trade show organizations are other potential markets for this growing technology. Nearly any application where relatively large amounts of data need to be stored and randomly accessed are suitable candidates for this emerging technology.
Other biometric verification techniques include fingerprint, retinal scanning, hand geometry, facial characteristics, voice patterns, and blood-vessel arrangement in the wrist or hand. Fingerprint identification is the most popular.
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