Datalogic Hand-held devices II Dokumentacja Pobierz pdf (Strona 10)

Page10 AllAboutBarCodes

Dedicated Bar Code Printers: These produce very rugged bar codes Dedicated printers come in several varieties,

including thermal and thermal transfer The best of them can produce bar codes that are not bothered by acids, rain,

sunlight, or various other problems These printers can also print a single tag or sticker easily and remove the label backing

automatically

Laser and Ink Jet Printers: Bar codes printed by these printers are comparable to those printed on dedicated label

printers In fact, the print quality is almost as good as on preprinted bar codes However, laser printers are not quite so

rugged as dedicated label printers, and they print a full sheet of labels at a time

Label Printers: Avery™ and Costar™ make small, thermal label printers that can print bar codes These printers may not be

the best choice for high-volume printing

Reading Bar Codes

Once you have a bar code in hand, you must read it and process the information Reading bar codes requires three basic

decisions You must decide on the input device, the decoder, and the interface The input device reads the bar code and

transmits the data to the decoder, which converts the data to ASCII characters The interface is the connection between the

decoder and the computer

Input Devices

Input devices (wands, CCDs, badge scanners, and lasers) are the direct contact between the user and the bar code No other

choice you make will have a greater impact on the usability of the system Naturally, there are several choices, in a range of

prices In general, you will get better service from more expensive devices, but this is not automatically so The choice of input

device is controlled by these factors:

Volume: Some input devices are inherently more usable and reliable than others If you have a low-volume application, any

input device will probably work well for you A high-volume operation will generally be better off with a high-grade input

device High-grade input devices are fast and reliable

Bar Code Quality: One of the advantages of high-grade input devices is their ability to read low-quality bar codes In

applications where bar codes are of poor quality to start with or are likely to be damaged, use of high-quality input devices

can save time and reduce errors

To select an input device, you must take all of these factors into consideration Once you have made a tentative decision, you

should test the system in as many real-world conditions as you can simulate

Get the input device a little dirty, damage the bar codes, print them with a slightly worn ribbon or cartridge, test it with an

untrained employee, and try to anticipate other problems that may happen during normal operation This way you can make

sure you have made the right choice The most common input devices are:

Wands: These are the most inexpensive input devices available  They work well for low-volume scanning but have some

disadvantages They require a relatively at surface, a fairly high quality bar code, and some skill on the part of the person

operating it However, in applications where someone must scan one bar code on a sheet full of bar codes, these are a

good choice

CCD (Charge-Coupled Device) Readers: These are the next step up from wands A CCD has a read head the same width

as the bar code (2 to 4” / 5 to 10 cm) The user sets the head of the reader on the bar code, and a series of LEDs illuminate

the bar code so it can be read This requires less skill than the wand, and it will work with most low-quality bar codes They

still require a relatively at surface, and the CCD must be within 025” / 05 cm of the bar code to read it The surface can be

slightly curved in the direction of the bars, but no more than about the curve of a 1-liter bottle

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Datalogic Hand-held devices II Dokumentacja Strona 10