Wand readers are the lowest cost "entry level" technology
used to read bar codes. Most wands look very much like ordinary
pens, designed to be held in much the same way. Wands usually have
no moving parts and rely on the user moving the optical head of
the wand over the code to produce the scanning signal for decoding.
Most wands are of the so called "dumb" type, meaning that
their only function is to convert the optical signal seen at the
tip into an analogue electrical signal that is then fed, usually
via the attached cable, to the host device for decoding (Wand Interface
An extension of the basic wand reader is to place some decoding
and/or memory storage in it. Such devices are usually described
as "smart", or "intelligent" wands. They process
the signal before transmitting to the host (e.g. converting to an
RS232 serial output signal). "Memory" wands serve a similar
function but have on-board memory to store the data for later downloading
to a host device.
The common features of all wand devices are that they require the
tip or head of the device to contact with and move across the bar
code or label. This provides a number of obvious and immediate limitations:
The surface being read
must be suitable for having the wand passed over it; it must be
robust to survive frequent readings. Codes printed on paper based
materials can suffer wear, leading to reading difficulties.
The user must be able
to get close to the code so that they can easily "swipe"
it with the wand.
Very small or very large
codes can be difficult for users to scan.
It takes some practice
to develop the required "knack" of obtaining good first
time reads; novices sometimes experience difficulties.
The surface bearing the
code must adequately reflect the light/dark differentiation. In
an attempt to protect delicate codes, users sometimes place some
form of clear plastic protection over them. However, if the plastic
itself is too reflective (or too thick), the wand will not be able
to get an accurate image from the code.
Wands really need to be
used on codes that are on a flat surface; reading around the curve
of a cylindrical object is either very difficult or impossible.
Wands are not really suited
to "high volume" applications. Apart from wear and tear
on wands, wear and tear on users can be a bigger problem!
Despite these limitations, wands are a very popular choice for low
volume/close proximity type applications. Low power consumption
makes them suitable for attachment to battery powered hand held
devices and their biggest benefit is of course their relatively