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Finger characteristics
Before deciding for one or more
fingers, you should note a number
of points.
•
Fingertips with a large number of
injuries, scars or an unclearly defined
structure are less suitable as a user
finger.
•
Where fingers are relatively thick,
use the smallest fingers on the hand,
i.e. the ring finger or small finger.
•
However, if the fingers are very
small, for instance in the case of chil-
dren, the thumb should be used.
•
In right-handed people, the finger-
tips of the left hand are less dam-
aged than in left-handed people and
vice-versa.
•
At least 2 fingers should be
scanned in per person, ideally one
from each hand, in order to have
an alternative in case of injury to a
finger or a whole hand.
•
Where the number of people is
limited, it makes sense to work with
a higher number of fingers, as at the
beginning it is possible to find out
the preferred finger.
Optimum finger guidance
The fingerprint module uses only
the biometric data of the fingertips
for personal identification. Reliable
operation is guaranteed provided
the following conditions are met.
•
Using the module calls for some
practice. Experience has shown that
recognition reliability increases with
frequency of use. We consequently
recommend you to practice correct
utilization before scanning in your
fingerprint.
•
Stand in an ergonomically com-
fortable position relative to the
sensor.
•
Stretch out the finger you wish to
scan in.
•
Draw the finger flat over the
sensor at around the last finger joint.
•
Exert a light pressure on the
sensor.
•
Ensure that you move the finger in
as straight a line as possible, without
„snaking". Avoid hesitating while
moving the finger if possible.
4
•
Do not move the finger too fast
or too slowly over the sensor. The
process should be completed within
a second.
•
For identification, pull the finger
over the sensor in the same way as
when reading in the fingerprint.
Read in fingerprints
Fingerprint scanning starts automati-
cally, as soon as the upper section of
the finger is drawn over the sensor
in an even movement. The best
results are obtained by placing the
finger flat in the finger recess at the
start of the downward movement
and laying the upper joint of the
finger section at the height of the
sensor (see Fig.1).
The sensor generates three pictures
when scanning in the fingerprint,
and searches for characteristic
features. The best of the pictures is
filed in the internal database. If the
characteristics have been successfully
detected, the fingerprint is saved.
Causes of faults
•
Dirty fingers can have a negative
impact on the recognition rate.
•
Injured fingers can have a nega-
tive impact on the recognition rate,
which is why we recommend
teach-in of at least 2 fingerprints per
person.
•
Wet or moist fingers can have a
negative impact on the recognition
rate.
•
Fingerprints of children can be
recognized, depending on build
and motor function, from around
6 years. Practise operation of the
sensor together with your child.
•
Dry fingers, e.g. when handling
solvents, can have a negative impact
on the recognition rate.
•
Swollen fingers, for example after
soaking, can have a negative impact
on the recognition rate.
•
Finger is drawn over the sensor at
a too steep angle and does not lie
flush on the surface (Fig. 2).
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