Operating Principles for
Very small fingerprint
sensors
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Progress in low-cost sensor systems
The first step is the movement from
z
Modular sensor devices Æ silicon
integrated sensor devices
–
Cost is now driven by silicon size
The second step is a new generation of
very small devices
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z
Small touch sensors
z
Small slide sensors
2
An example of a very small touch sensor
Size of active
sensing area
AuthenTec AES-3500
small touch sensor
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How do small touch sensors work
Acquiring enough repeatable information to match
accurately
z
Use the higher density small-scale feature
information captured in high quality TruePrint images
to perform matching using less skin area
Allowing flexible finger positioning on the sensor
z
Use template compositing to store areas of finger
skin larger than the sensor itself
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High Resolution
TruePrint Imaging
AuthenTec’s very
small touch sensors
can capture highly
detailed images
with excellent
repeatably.
This image is from
an AES-3500
sensor running
experimental high
resolution control
software.
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High Resolution
TruePrint Imaging
A topographic
analysis program
highlights some of
the detail that can
be extracted from
the image.
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Flexible finger positioning using a
composite template – concept illustration
Single touch images
Multiple touches during the enroll process
z Are logically interconnected
z Into a larger composite template
Composite template
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What information can be contained
in a composite template?
Template is:
z
Several views of a
finger
z
Location of each
view relative to
others
z
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•Relative location
• Confidence
Image representation
Pattern representation
Feature (minutia) data
Image and/or
feature data for
each view
Other data
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Verification using a composite template
Conceptually:
z
z
Template
Compare live view against
each template view
Live
image
Final score is statistical
combination of all
evaluations
• Relative Location
• Match Score
Final score
calculation
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Match or
non-match
How do small slide sensors work
Acquiring enough repeatable information to match
accurately
z
Slide the finger across the sensor
z
Capture a “stream” of small image slices
Allowing flexible finger positioning on the sensor
z
Same sliding usage method allows flexible finger
positioning
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Slide sensor operation
Slide sensors are required where lowest cost is paramount.
slide
User slides the finger
across the sensor
Sensor
Stream of image slices
Template
Small local
processor
Match or
non-match
Inexpensive devices usually have small processors.
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Slide sensor processing options
Stream of
image slices
Stitched
image
segments
Finger movement
Sensor
Matching
Options
=
Match raw
slices
Increasing processor load
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|
Match
stitched
image
segments
Comparison of small sensors
Sensor
Cost
Ease of
use
Typical
biometric
accuracy
Front
panel
footprint
Interface
bandwidth
needed
Small
touch
sensor
Very low
Best
Best
Small
Low
Small
slide
sensor
Lowest
Good
Good
Smallest
High
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For more information …
Click here to learn
about fingerprint
Matching methods
Click here to learn
about Specifying
commercial
biometric systems
Back to Beginning
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