Barcode Education

A wand is a pen-type scanner requiring physical contact with a bar code when scanning. The wand is simple to use but does require the user to maintain a tilt angle of 60º-85º above the label surface. This controls the reflectance of the light that is absorbed and a constant or continuous scanning motion across the bar code must be maintained to regulate the sample rate. The speed in which the user moves across the bar code is also important. If the continuous scanning motion is too slow or too fast, the decoder may not be able to detect the signal sent to it by the wand.

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.

In overall cost, Wands are about one-tenth the price of a laser gun and about one-fifth the price of a CCD reader. However there are a number of trade-offs that need to be considered before cost. First, a wand is a contact scanner and, therefore, must come into direct contact with the bar code. If the nature of the application does not permit the user to come into direct contact with the bar code, then another solution must be considered, such as a laser scanner. Secondly, a wand can not scan nearly as fast as a CCD reader or laser scanner. A wand is a manual scanning device in that a tilt angle and constant scanning motion must be met in order to obtain a good read. CCD readers and laser scanners simplify these procedures electronically through features such as automatic gain control and self-scanning.

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.