Toshiba Qosmio X870 - Manual (Page 48)

Do not touch the sensor with a wet finger or any wet objects - keep the
sensor surface dry and free from water vapor.
Do not touch the sensor with a soiled or dirty finger as minute foreign
particles of dust and dirt may scratch it.
Do not paste stickers or write on the sensor.
Do not touch the sensor with a finger or any other object which may
have a build-up of static electricity on it.
Observe the following before you place your finger on the sensor whether
for fingerprint enrollment/registration or recognition.
Wash and dry your hands thoroughly.
Remove static electricity from your fingers by touching any metal
surface. Static electricity is a common cause of sensor failures,
especially when the weather is dry.
Clean the sensor with a lint-free cloth - do not use detergent or any
other chemicals to clean the sensor.
Avoid the following finger conditions for enrollment or recognition as
they may result in fingerprint enrollment errors or a drop in the
fingerprint recognition success rate
Soaked or swollen finger, for example as may occur after taking a
bath.
Injured finger
Wet finger
Soiled or oily finger
Extremely dry skin condition on finger
Observe the following to improve the fingerprint recognition success rate.
Enroll two or more fingers.
Enroll additional fingers if a recognition failure often occurs when using
already enrolled fingers.
Check the condition of your finger - any conditions which have
changed since enrollment, such as injury, rough skin, and extremely
dry, wet, soiled, dirty, oily, soaked or swollen fingers, may lower the
recognition success rate. Also if the fingerprint is worn down or the
finger becomes thinner or fatter, the recognition success rate may be
lowered.
As the fingerprint for each finger is different and unique you should
ensure that only the registered or enrolled fingerprint or fingerprints
are used for identification.
Check the position and speed at which you swipe your finger across
the sensor - please refer to the preceding drawing.
The fingerprint sensor compares and analyzes the unique
characteristics in a fingerprint. However, there may be instances
where certain users are unable to register their fingerprints due to
insufficient unique characteristics in their fingerprints.
The recognition success rate may differ from user to user.
X870
User's Manual 3-7